Adhesive composition, adhesive layer, adhesive sheet, and display comprising the same

Abstract

The present invention relates to an adhesive composition, an adhesive layer and an adhesive sheet manufactured using the same, and a display including the same, and relates to an adhesive composition and an adhesive sheet manufactured using the same, and a display including the same, which can provide proper adhesion without including an acid component, without reducing a gel fraction, without generating a residue, can prevent an over-increase in a maintenance period, and is eco-friendly. The adhesive composition includes an acrylic copolymer polymerized by including a compound represented by Chemical Formula 1 below, and a cross-linking agent selected from one or more of an isocyanate compound, an epoxy-based compound, an oxazoline-based compound, an aziridine-based compound, and a metal chelate-based compound, the isocyanate compound being at least one selected from an aliphatic isocyanate-based compound and an alicyclic isocyanate-based compound, in Chemical Formula 1, R1 is hydrogen or a methyl group, and R2 is a biomass-derived hydrocarbon group having 1 to 100 carbon atoms.

Description

Technical Field

[0001] This invention relates to adhesive compositions and adhesive sheets manufactured using the same, as well as displays comprising the adhesive sheets. Background Technology

[0002] The image display device consists of a liquid crystal cell containing liquid crystal and a polarizing plate, which are mainly bonded together by forming an adhesive layer on one side of the polarizing plate. In this case, the polarizing plate contains a polarizer that performs the polarization function, and a triacetyl cellulose (TAC) film is attached to one or both sides as a protective film for the polarizer. Furthermore, to improve the functionality of the liquid crystal display device, protective films such as phase retardation plates, wide-angle compensation plates, and brightness enhancement plates can be attached instead of the triacetyl cellulose (TAC) film which provides general protection.

[0003] On the other hand, adhesive layers in such image display devices serve a variety of purposes. For example, in the manufacturing process of optical components, surface-protective adhesive sheets are attached to optical components such as polarizers and retardation plates to prevent surface scratches. These surface-protective adhesive sheets are structures formed by coating a surface-protective substrate film with an adhesive layer for the surface-protective substrate film. The adhesive used to adhere the surface-protective substrate film requires a lower adhesive strength than that used in typical optical components to facilitate peeling. For surface-protective adhesive sheets without acid components, there is a problem of reduced gel fraction and excessively increased adhesive strength, resulting in insufficient function as a surface-protective film and excessively increased curing time.

[0004] As another example, when a polarizing plate is attached to an optical component such as a liquid crystal cell, it may be peeled off from the optical component such as the liquid crystal cell for various reasons and then reattached. In this case, the adhesive layer for the polarizing plate, which is used to attach the polarizing plate to the liquid crystal cell, needs to be easy to separate from the liquid crystal cell while maintaining adhesion (reworkability).

[0005] On the other hand, for adhesives containing acids, the metal layers in optical components that are the adhered materials may corrode due to the acid components. Therefore, acid-free adhesives are required. However, if the acid is removed from the adhesive composition, there is a problem of excessively increased adhesion, making it difficult to separate the optical components. Furthermore, the aforementioned adhesives are manufactured using petrochemical products derived from petroleum separation and refining processes. Therefore, according to international agreements on strictly controlling greenhouse gas emissions, such petrochemical products may incur significant environmental costs. Therefore, the development of environmentally friendly materials that can replace existing petrochemical products is underway.

[0006] Korean Patent Publication No. 10-2020-0025044 discloses an adhesive composition that does not contain acidic functional groups, but it has problems such as excessively high adhesion and peel strength, making it difficult to apply to surface protection substrate films and still lacking environmental friendliness. Korean Registered Patent No. 10-5694629 discloses an adhesive film that does not require a curing period after coating, but because the resin composition of the adhesive contains acid compounds and does not take into account the metal layer, corrosion may occur due to the migration of acid components. Therefore, it is still insufficient for use in polarizing plates, especially in adhesive compositions for polarizing plates used in bonding optical components to polarizing plates.

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: Korean Patent Publication No. 10-2020-0025044

[0010] Patent Document 2: Korean Patent Registration No. 10-5694629 Summary of the Invention

[0011] Methods for solving problems

[0012] To address the problems of the prior art, the present invention aims to provide an adhesive composition that, by not containing acid components, minimizes gel fraction loss, provides suitable adhesion when bonded and / or attached to optical components, exhibits good adhesion to the substrate, does not leave residue on the adhered material upon separation and / or peeling, and prevents excessive curing time.

[0013] In addition, the present invention aims to provide an adhesive composition that not only does not exhibit turbidity and can prevent corrosion of the bonded materials, but also provides environmental friendliness.

[0014] In addition, the present invention aims to provide an adhesive sheet, an adhesive layer with excellent reworkability, and a display comprising the thereof, which can prevent corrosion of the adhered material while being environmentally friendly, and provide suitable adhesion so as not to produce residue on the adhered material during separation and / or peeling, and is therefore suitable for temporary attachment to protect the surface of the adhered material.

[0015] However, the problem to be solved by this application is not limited to the problems mentioned above, and those skilled in the art should be able to clearly understand other problems not mentioned based on the following description.

[0016] Methods for solving problems

[0017] To achieve the above objectives, the present invention provides an adhesive composition comprising: an acrylic copolymer polymerized from a compound represented by the following chemical formula 1; and a crosslinking agent selected from one or more isocyanate compounds, epoxy compounds, oxazoline compounds, aziridine compounds, and metal chelate compounds, wherein the isocyanate compound is selected from at least one aliphatic isocyanate compounds and alicyclic isocyanate compounds.

[0018] [Chemical Formula 1]

[0019]

[0020] (In the above chemical formula 1,

[0021] R1 is hydrogen or methyl.

[0022] R2 is a hydrocarbon group derived from biomass with 1 to 100 carbon atoms.

[0023] The above adhesive composition can be an adhesive composition for polarizing plates.

[0024] The content of the crosslinking agent can be from 0.1 parts by weight to 0.4 parts by weight relative to 100 parts by weight of the acrylic copolymer.

[0025] The adhesive force of the adhesive layer formed by the above adhesive composition can be more than 1N / 25mm and less than 5N / 25mm.

[0026] The above adhesive composition can be an adhesive composition for surface protective substrate films.

[0027] The content of the crosslinking agent can be from 0.5 parts by weight to 2.5 parts by weight relative to 100 parts by weight of the acrylic copolymer.

[0028] The adhesive strength of the adhesive sheet formed from the above adhesive composition can be less than 1 N / 25 mm.

[0029] The adhesive composition described above may also contain a crosslinking aid.

[0030] The aforementioned crosslinking aid can be selected from sodium salts (Na+). + ) series, calcium salts (Ca 2+ One or more of the ) series and the tin (Sn) series compounds.

[0031] The content of the crosslinking aid can be from 0.01 parts by weight to 0.1 parts by weight relative to 100 parts by weight of the acrylic copolymer.

[0032] The content of the compound represented by the above chemical formula 1 may be 30 to 80 by weight relative to the total weight of the monomers used in the polymerization of the above acrylic copolymers.

[0033] The aforementioned acrylic copolymers may not contain acidic functional groups.

[0034] The adhesive composition described above may also contain one or more silane coupling agents selected from the group consisting of compounds represented by the following chemical formula 2.

[0035] [Chemical Formula 2]

[0036]

[0037] (In the above chemical formula 2,

[0038] R8 is an alkyl group having 1 to 12 carbon atoms or an alkoxy group having 1 to 12 carbon atoms.

[0039] R9 is a divalent aliphatic hydrocarbon group with 1 to 30 carbon atoms.

[0040] R 10 To R 12 Each of the following is independently hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms.

[0041] The content of the above-mentioned silane coupling agent can be from 0.01 to 3 parts by weight relative to 100 parts by weight of the acrylic copolymer.

[0042] The biomass content of the adhesive layer formed by the above adhesive composition, calculated according to ASTM D6866 and Formula 1 below, can be 50% or more.

[0043] [Formula 1]

[0044] Biomass quality (%) = (Number of carbon atoms from biomass source / Total number of carbon atoms) × 100

[0045] The adhesive composition described above may also include one or more adhesive compositions selected from the group consisting of antistatic agents, surfactants, adhesion promoters and anti-coagulants.

[0046] In addition, the present invention relates to an adhesive layer comprising the above-described adhesive composition.

[0047] In addition, the present invention relates to an adhesive sheet comprising the above-described adhesive layer and substrate film.

[0048] In addition, the present invention relates to a display comprising the above-described adhesive sheet.

[0049] Invention Effects

[0050] The present invention provides an adhesive composition that provides suitable adhesion, good bonding to the substrate, and leaves no residue on the bonded material upon separation and / or peeling, thereby satisfying ideal adhesive properties for polarizing plates and / or optical components.

[0051] In addition, the present invention can provide an adhesive composition that prevents excessive curing time, does not cause clouding or corrosion of the metal layer of the liquid crystal cell, and is environmentally friendly because it contains an acrylic copolymer polymerized from a mixture of biomass-derived monomers.

[0052] In addition, the present invention can provide an adhesive composition for a surface protective substrate film that, even without containing acid components, can minimize the decrease in gel fraction to provide adequate adhesion and leaves no residue on the adhered material upon peeling, thus being suitable for temporary adhesion to achieve surface protection of the adhered material.

[0053] In addition, the present invention can provide an adhesive composition for a polarizing plate that can provide a suitable adhesion force to the glass substrate or the like of the optical component when the polarizing plate is bonded to other optical components, and does not leave residue on the optical component when separated from the polarizing plate. Therefore, the fixing force and reworkability are both suitable when bonded to the polarizing plate.

[0054] In addition, the present invention can provide an environmentally friendly adhesive sheet that provides suitable adhesion and a display containing the same. Attached Figure Description

[0055] Figure 1 This is a diagram illustrating a display comprising a surface protection adhesive sheet and a polarizing plate adhesive layer according to an embodiment of the present invention.

[0056] Symbol Explanation

[0057] 100: Polarizing plate

[0058] 110: Polarizer

[0059] 120: Adhesive

[0060] 130: Protective film

[0061] 140-1: Adhesive layer for surface protective substrate film

[0062] 140-2: Adhesive layer for polarizing plates

[0063] 150: Surface protective substrate film

[0064] 160: Glass substrate of liquid crystal cell Detailed Implementation

[0065] This invention relates to adhesive compositions, adhesive sheets comprising the same, and displays. The adhesive compositions are acrylic copolymers polymerized from monomers derived from a mixture of biomass sources, achieving a biomass content of 50% or higher according to ASTM D6866. They also include at least one isocyanate compound selected from aliphatic and alicyclic isocyanate compounds, epoxy compounds, oxazoline compounds, aziridine compounds, and metal chelate compounds as crosslinking agents. This provides suitable adhesion and, due to good adhesion to the substrate, leaves no residue on the bonded material upon peeling, thus satisfying ideal adhesive properties for polarizing plates and / or optical components. The aforementioned adhesive compositions can provide suitable adhesion in laminates containing optical components such as polarizing plates and liquid crystal cells, depending on the application.

[0066] Furthermore, since the adhesive composition of the present invention does not contain acid components, it does not cause cloudiness, does not corrode metal layers such as ITO, and can shorten the curing period even without acid components.

[0067] Biomass is a collective term for plants that synthesize organic matter by absorbing solar energy, and for the animals, microorganisms, and other biological organisms that feed on them, including secondary products and waste derived from these organisms. Compounds derived from biomass contain radioactive carbon isotopes that are only found in naturally occurring substances. 14 C), unlike those that do not contain radioactive carbon isotopes ( 14 C) Petroleum-derived compounds.

[0068] At this point, the biomass of the adhesive sheet formed by the adhesive composition can be determined by measuring the radiocarbon isotopes contained in the adhesive composition. 14 The concentration of C) is used to calculate the biomass content, but in order to determine the biomass content, it is necessary to entrust a testing institution that can perform radioactive isotope testing, which may consume a lot of time and cost.

[0069] Therefore, the biomass content of the adhesive composition, adhesive layer and adhesive sheet comprising the present invention can be calculated according to ASTM D6866 above and according to the following formula 1, and the biomass content calculated in this way can be 50% or more.

[0070] [Formula 1]

[0071] Biomass quality (%) = (Number of carbon atoms from biomass source / Total number of carbon atoms) × 100

[0072] The present invention will now be described in more detail. However, the terminology used in this specification is intended to describe embodiments and is not intended to limit the invention. In this specification, the term "adhesive sheet" can mean both an adhesive layer and a film. Specifically, in this specification, the adhesive sheet for surface protection includes an adhesive layer for a surface protective substrate film and a surface protective substrate film.

[0073] <Adhesive Composition>

[0074] The adhesive composition of the present invention comprises an acrylic copolymer polymerized from a monomer of formula 1 derived from biomass, and a crosslinking agent that is free of acid components and designed to prevent a decrease in gel fraction. Additionally, it may contain a crosslinking aid capable of further shortening curing time, a silane coupling agent having a triethoxysilyl group, and, if desired, one or more selected from the group consisting of surfactants, adhesion promoters, and anti-gelling agents.

[0075] Acrylic copolymers

[0076] The adhesive composition of the present invention comprises an acrylic copolymer polymerized from a monomer derived from biomass, characterized in that it comprises an acrylic copolymer polymerized from a compound represented by the following chemical formula 1.

[0077] <Chemical Formula 1>

[0078]

[0079] In the above chemical formula 1, R1 is hydrogen or methyl, and R2 is a hydrocarbon group derived from biomass with 1 to 100 carbon atoms.

[0080] The hydrocarbon groups from the above-mentioned biomass sources are not particularly limited as long as they come from biomass, that is, plants that synthesize organic matter by accepting solar energy and biological organisms such as animals and microorganisms that feed on them. They can be obtained cheaply and easily by using saturated or unsaturated fatty acids collected from biological organisms such as plants and animals as raw materials and then alcoholizing or esterifying them.

[0081] The biomass-derived hydrocarbon group of the present invention may contain saturated or unsaturated hydrocarbon groups, and may contain chain or alicyclic hydrocarbon groups.

[0082] As the aforementioned saturated or unsaturated chain hydrocarbon groups, they can be straight-chain or branched, and examples include alkyl and alkenyl groups.

[0083] Examples of saturated or unsaturated alicyclic hydrocarbon groups, including monocyclic or polycyclic alicyclic hydrocarbon groups, include cycloalkyl, cycloalkenyl containing double bonds, and adamantyl.

[0084] In addition, the aforementioned hydrocarbon groups may include groups composed of saturated or unsaturated chain or alicyclic hydrocarbon groups. That is, examples include combinations of alkyl and alkenyl groups, combinations of alkyl and cycloalkyl groups, combinations of alkyl and cycloalkenyl groups, and combinations of cycloalkyl and cycloalkenyl groups.

[0085] The compound represented by the above chemical formula 1 may more specifically include one or more compounds selected from the group consisting of compounds represented by the following chemical formulas 1-1 to 1-3.

[0086] <Chemical Formula 1-1>

[0087]

[0088] <Chemical Formulas 1-2>

[0089]

[0090] <Chemical Formulas 1-3>

[0091]

[0092] The content of the compound represented by the above chemical formula 1 can be 30 to 80% by weight relative to the total weight of the monomers used in the polymerization of the above acrylic copolymers. When the above content range is met, it has the advantage of providing an environmentally friendly adhesive composition because the target biomass quality can be achieved.

[0093] In addition to the compounds represented by Chemical Formula 1 above, the acrylic copolymers of the present invention may also contain acrylic monomers that do not contain acidic functional groups. Examples of such acidic functional groups include carboxyl groups, sulfonic acid groups, or phosphate groups. When using monomers containing these acidic functional groups, corrosion may occur when used in metallic adhesive materials.

[0094] As an acrylic monomer that does not contain the aforementioned acidic functional groups, it can be polymerized, for example, by further comprising one or more monomers selected from the group consisting of alkyl (meth)acrylates, hydroxyl-containing monomers, amide-containing monomers, amino-containing monomers, imide-containing monomers, epoxy-containing monomers, and ether-containing monomers, but is not limited thereto.

[0095] The term "(meth)acrylate" is not specifically defined, and "(meth)acrylate" refers to both acrylate and methacrylate.

[0096] Specific examples of the aforementioned alkyl methacrylates include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, sec-butyl methacrylate, tert-butyl methacrylate, isobutyl methacrylate, pentyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, isooctyl methacrylate, n-nonyl methacrylate, isononyl methacrylate, n-decyl methacrylate, isodecyl methacrylate, n-dodecyl methacrylate, n-tridecyl methacrylate, n-tetradecyl methacrylate, and phenoxyethyl methacrylate.

[0097] The content of the alkyl methacrylate can be 10 to 70% by weight relative to the total weight of monomers used in the polymerization of the above-mentioned acrylic copolymers. It is preferred to meet the above content range from the perspective of improving adhesion and durability.

[0098] Examples of hydroxyl-containing monomers mentioned above include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylaurate (meth)acrylate, methyl (4-hydroxymethylcyclohexyl)acrylate, N-hydroxymethyl (meth)acrylamide, vinyl alcohol, allyl alcohol, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, diethylene glycol monovinyl ether, 2-acryloyloxyethyl-2-hydroxyethyl phthalate, etc.

[0099] Examples of the amide-containing monomers mentioned above include (meth)acrylamide, N-isopropylacrylamide, N-tert-butylacrylamide, 3-hydroxypropyl (meth)acrylamide, 4-hydroxybutyl (meth)acrylamide, 6-hydroxyhexyl (meth)acrylamide, 8-hydroxyoctyl (meth)acrylamide, and 2-hydroxyethylhexyl (meth)acrylamide.

[0100] Examples of amino-containing monomers include N,N-(dimethylamino)ethyl methacrylate, N,N-(diethylamino)ethyl methacrylate, and N,N-(dimethylamino)propyl methacrylate. Examples of imide-containing monomers include cyclohexylmaleimide and isopropylmaleimide.

[0101] Examples of epoxy-containing monomers include glycidyl (meth)acrylate and methyl glycidyl (meth)acrylate. Examples of ether-containing monomers include 3-methoxybutyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 3-methoxypropyl (meth)acrylate, 2-methoxybutyl (meth)acrylate, methoxypolyethylene glycol acrylate, ethoxydiethylene glycol (meth)acrylate, and ethyl carbitol (meth)acrylate, etc., with an addition molar number of 1 to 15 of ethylene oxide.

[0102] In addition to the monomers mentioned above, the acrylic copolymers may further contain other monomers commonly used in the art to which this invention pertains, without reducing adhesion. For example, the content may be less than 10% by weight relative to the total weight of monomers used in the polymerization of the acrylic copolymers.

[0103] The weight-average molecular weight (Mw, converted from polystyrene) of the aforementioned acrylic copolymers, as determined by gel permeation chromatography (GPC), can be from 500,000 to 2,000,000, more preferably from 700,000 to 1,700,000. When the weight-average molecular weight of the acrylic copolymer is below 500,000, the adhesive film after UV polymerization and curing has a simple internal chain structure and short length, which is detrimental to reliability due to factors such as the generation of bubbles, and may also lead to reduced durability due to discoloration. When the weight-average molecular weight is above 2,000,000, the viscosity of the adhesive resin composition is too high during the manufacture of the adhesive film, requiring the dilution of a large amount of monomer to achieve the appropriate viscosity required for manufacturing. This may necessitate high energy during UV polymerization and curing, or leave unreacted monomer residues.

[0104] The method for manufacturing the above-mentioned acrylic copolymers is not particularly limited. For example, methods commonly used in the technical field of this invention, such as bulk polymerization, solution polymerization, emulsion polymerization, suspension polymerization, and UV polymerization, can be used. Preferably, solution polymerization or UV polymerization can be used.

[0105] The acrylic copolymer of the present invention is preferred from the perspective of corrosion resistance because it is substantially acid-free. "Substantially acid-free" means that the acid value of the acrylic copolymer is typically below 1 mg KOH / g, preferably below 0.5 mg KOH / g, and particularly preferably 0.

[0106] Crosslinking agent

[0107] The adhesive composition of the present invention may include a crosslinking agent to enhance intermolecular bonding. The crosslinking agent may include one or more isocyanate compounds, epoxy compounds, oxazoline compounds, aziridine compounds and metal chelate compounds selected from aliphatic isocyanate compounds and alicyclic isocyanate compounds.

[0108] The aforementioned acrylic copolymers do not contain acidic functional groups, thus the gel fraction is significantly reduced. However, when the aforementioned crosslinking agent is included, excessive reduction in the gel fraction can be prevented to achieve an adhesive strength sufficient to function as an adhesive. Furthermore, appropriate gel fraction and reworkability can be provided so that no residue is left when separating and / or peeling from the bonded material.

[0109] The above-mentioned isocyanate compound selected from aliphatic isocyanate compounds and alicyclic isocyanate compounds is a compound containing more than one isocyanate group (-N=C=O) per molecule, and may contain isocyanurate group, biuret group, ureocarbamate group, oxadiazinetrione group, urea group, carbamate group. From the perspective of viscosity adjustment, it is preferred that the final structure does not contain an aromatic ring.

[0110] The aliphatic and alicyclic isocyanate compounds mentioned above are not particularly limited. Examples include hexamethylene diisocyanate (HDI), tetramethylene diisocyanate, methyl-1,8-octamethylene diisocyanate (trimeric triisocyanate), pentamethylene diisocyanate, 2,2,4-trimethyl-1,6-hexane diisocyanate, lysine diisocyanate, hexamethylene diisocyanate isocyanurate, 4,4'-methylenebis(cyclohexylisocyanate), and isophorone diisocyanate, but are not limited to these.

[0111] Examples of the aforementioned epoxy-based crosslinking agents include ethylene glycol diglycidyl ether, triglycidyl ether, trimethylolpropane triglycidyl ether, N,N,N',N'-tetraglycidyl ethylenediamine, and glycerol diglycidyl ether. These can be used alone or in combination of two or more.

[0112] Examples of the aforementioned oxazoline-based crosslinking agents include copolymers obtained by polymerizing monomers containing at least one oxazoline group, such as 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2-isopropenyl-4-methyl-2-oxazoline, and 2-isopropenyl-5-ethyl-2-oxazoline. These can be used alone or in combination of two or more.

[0113] Examples of the aforementioned aziridine crosslinking agents include N,N'-toluene-2,4-bis(1-aziridinecarboxamide), N,N'-diphenylmethane-4,4'-bis(1-aziridinecarboxamide), triethylene melamine, bis(isophthaloyl-1-(2-methylaziridine), and tri-1-aziridineylphosphine oxide. These can be used alone or in combination of two or more.

[0114] Examples of metal chelate crosslinking agents include compounds formed by coordination of multivalent metals such as aluminum, iron, zinc, tin, titanium, antimony, magnesium, and / or vanadium with acetylacetone or ethyl acetoacetate. These can be used alone or in combination of two or more.

[0115] In this invention, the crosslinking agent can be one of the following: aliphatic isocyanate compounds, alicyclic isocyanate compounds, epoxy compounds, oxazoline compounds, aziridine compounds, and metal chelate compounds, or two or more can be used in combination.

[0116] The content of the crosslinking agent relative to 100 parts by weight of the acrylic copolymer can be from 0.1 parts by weight to 2.5 parts by weight, preferably from 0.1 parts by weight to 1.0 parts by weight. When the content of the crosslinking agent is higher than the above range, the adhesive force may be excessively reduced, resulting in decreased adhesion. When the content of the crosslinking agent is lower than the above range, insufficient cohesion may occur due to incomplete crosslinking reaction, potentially leading to insufficient adhesion and durability.

[0117] Furthermore, by adjusting the content of the crosslinking agent, the adhesive composition of the present invention can be manufactured to provide an adhesive composition with suitable adhesion for use in a laminate containing optical components such as polarizing plates and liquid crystal cells.

[0118] As an example, in the case of manufacturing a surface-protecting adhesive sheet suitable for temporary adhesion to achieve surface protection of the adhered material, in the adhesive composition for manufacturing the surface-protecting substrate film of the surface-protecting adhesive sheet, the content of the crosslinking agent can be from 0.5 parts by weight to 2.5 parts by weight, preferably from 0.5 parts by weight to 1.0 parts by weight, relative to 100 parts by weight of the acrylic copolymer. When the above content range is met, it is preferred from the perspective of ensuring the gel fraction in the early stage of curing.

[0119] As another example, in the case of forming an adhesive layer for a polarizing plate that has the characteristics of easy separation and maintained adhesion (reworkability) when bonding a polarizing plate and a liquid crystal cell, in the adhesive composition for manufacturing the polarizing plate adhesive layer, the content of the crosslinking agent can be 0.1 to 0.5 parts by weight relative to 100 parts by weight of the acrylic copolymer. From the viewpoint of durability and shortening curing time, it is preferable to be 0.1 to 0.4 parts by weight. When the above content range is met, adhesion can be ensured due to appropriate crosslinking, and the curing period can be shortened by more than 50% compared to that required without acid.

[0120] Crosslinking aids

[0121] The adhesive composition of the present invention may further include a crosslinking aid to increase the gel fraction by further increasing the degree of crosslinking.

[0122] The aforementioned crosslinking aids may be selected from one or more compounds of the sodium (Na+) series, calcium (Ca2+) series, and tin (Sn) series. Examples include sodium 2-ethylhexanoate, sodium ricinoleate, calcium 2-ethylhexanoate, and dibutyltin dilaurate, but are not limited thereto.

[0123] By including the aforementioned crosslinking aid, the gel fraction, which is reduced due to the absence of acid components in the acrylic copolymer contained in the adhesive composition, can be further increased, thereby shortening the curing period of the adhesive.

[0124] The content of the crosslinking aid can be from 0.01 parts by weight to 0.1 parts by weight relative to 100 parts by weight of the acrylic copolymer, preferably from 0.02 parts by weight to 0.08 parts by weight. When the above content range is met, it is preferred from the perspective of accelerating the increase of gel fraction and shortening the curing period.

[0125] Silane coupling agents

[0126] The adhesive composition of the present invention may further comprise one or more silane coupling agents selected from the group consisting of compounds represented by the following chemical formula 2.

[0127] The silane coupling agent selected from the group consisting of compounds represented by chemical formula 2 can improve the compatibility of the adhesive composition, increase the adhesion, and inhibit the generation, lifting and breakage of bubbles in the adhesive layer.

[0128] The aforementioned silane coupling agents may contain nitrogen or sulfur atoms, in which case they can provide adhesion durability and reliability even when placed under high heat and high humidity conditions for extended periods.

[0129] <Chemical Formula 2>

[0130]

[0131] In the above chemical formula 2, R8 is an alkyl group with 1 to 12 carbon atoms or an alkoxy group with 1 to 12 carbon atoms, R9 is a divalent aliphatic hydrocarbon group with 1 to 30 carbon atoms, and R 10 To R 12 Each of them is independently hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms.

[0132] Specifically, from the perspective of achieving the objectives and effects of the present invention, the above-mentioned silane coupling agent preferably has a trimethoxysilane group.

[0133] The compound represented by the above chemical formula 2 can be, for example, the compound represented by the following chemical formula 2-1.

[0134] <Chemical Formula 2-1>

[0135]

[0136] The content of the silane coupling agent can be from 0.01 to 3 parts by weight, preferably from 0.1 to 2 parts by weight, relative to 100 parts by weight of the acrylic copolymer. Within the above range, the durability and adhesion of the adhesive layer formed by the adhesive composition can be improved.

[0137] additive

[0138] The above-described adhesive composition may also include, as needed, conventional additives known in the art to adjust the desired adhesion, cohesive force, tack, elastic modulus, glass transition temperature, etc. For example, it may contain one or more selected from the group consisting of antistatic agents, surfactants, adhesion promoters, and anti-gelling agents.

[0139] The adhesive composition of the present invention may further include an antistatic agent, which may be an ionic antistatic agent comprising an ionic salt composed of anions and cations, which can impart ionic conductivity to the adhesive layer formed by the adhesive composition of the present invention.

[0140] The aforementioned ionic antistatic agent may contain alkali metal salts, ionic liquids, or ionic solids, preferably ionic solids.

[0141] By incorporating ionic solids as ionic antistatic agents, the time-dependent stability of the adhesive composition and the durability of the adhesive layer can be improved. Furthermore, the ionic solids exhibit high compatibility with the other components mentioned above, allowing the adhesive composition of the present invention to maintain high transparency.

[0142] The cations of the aforementioned ionic solids may include imidazolium, pyridinium, alkylammonium, alkylpyrrolidineium, and / or alkylphosphonium, etc.

[0143] In some embodiments, the content of the ionic antistatic agent may be from 0.01 to 5 parts by weight relative to 100 parts by weight of the acrylic copolymer. Within this range, the antistatic properties of the adhesive layer can be improved, and the durability of the adhesive layer can be maintained excellently.

[0144] The adhesive composition of the present invention can use surfactants to further improve film formation, preferably silicone-based, fluorine-based, ester-based, cationic, anionic, nonionic, amphoteric surfactants, etc.

[0145] The aforementioned silicone surfactants include, for example, commercially available products such as DC3PA, DC7PA, SH-11PA, SH-21PA, and SH-8400 from Dow Corning Toray Silicones, and TSF-4440, TSF-4300, TSF-4445, TSF-4446, TSF-4460, and TSF-4452 from GE Toshiba Silicones.

[0146] The aforementioned fluorinated surfactants include, for example, commercially available products such as MEGAFACE F-470, F-471, F-475, F-482, F-489, and F-554 from Dai Nippon Ink Chemical Industry Co., Ltd.

[0147] Other commercially available products that can be used include KP (Shin-Etsu Chemical Co., Ltd.), POLYFLOW (Kyoeisha Chemical Co., Ltd.), EFTOP (Tochem Products Co., Ltd.), MEGAFACE (Dai Nippon Ink Chemical Co., Ltd.), Flourad (Sumitomo 3M Co., Ltd.), Asahi guard, Surflon (Asahi Glass Co., Ltd.), SOLSPERSE (Lubrisol), EFKA (EFKA Chemical Co., Ltd.), PB 821 (Ajinomoto Co., Ltd.), and the Disperbyk series (BYK-chemi).

[0148] The surfactants exemplified above can be used alone or in combination of two or more, and their content is typically 0.01 to 5 parts by weight, preferably 0.05 to 2 parts by weight, relative to 100 parts by weight of the adhesive composition.

[0149] The adhesive composition of the present invention may use a bonding accelerator to improve the bonding force, the content of which is typically 0.01 to 5 parts by weight, preferably 0.05 to 2 parts by weight, relative to 100 parts by weight of the adhesive composition.

[0150] The types of adhesion promoters mentioned above are not particularly limited. Specific examples of usable adhesion promoters include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri(2-methoxyethoxy)silane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-epoxypropoxypropyltrimethoxysilane, 3-epoxypropoxypropylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-chloropropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-isocyanate propyltrimethoxysilane, and 3-isocyanate propyltriethoxysilane, etc.

[0151] The type of anti-gelling agent is not particularly limited, but as specific examples that can be used, sodium polyacrylate, etc., can be mentioned. The content of the anti-gelling agent is usually 0.01 to 5 parts by weight, preferably 0.05 to 2 parts by weight, relative to 100 parts by weight of the adhesive composition.

[0152] <Adhesive layer, adhesive sheet, and display>

[0153] The scope of this invention includes adhesive layers, adhesive sheets, and displays comprising the above-described adhesive compositions. In particular, the biomass content of adhesive layers manufactured from the adhesive compositions of this invention, calculated according to ASTM D6866 and Formula 1 below, can be 50% or more.

[0154] <Formula 1>

[0155] Biomass quality (%) = (Number of carbon atoms from biomass source / Total number of carbon atoms) × 100

[0156] Meeting the above-mentioned biomass content requirements allows for an increase in the carbon content of biomass-derived adhesives without increasing atmospheric carbon dioxide levels, thus making it environmentally friendly. Furthermore, applying adhesive sheets meeting these biomass content requirements to displays is preferable from the perspective of avoiding any environmental cost burden.

[0157] The adhesive layer manufactured using the adhesive composition of the present invention is more preferably an adhesive layer for a surface protective substrate film. The aforementioned adhesive layer for a surface protective substrate film can be formed by coating the adhesive composition onto a release film coated with an organosilicon release agent. The aforementioned adhesive layer for a surface protective substrate film can be formed using an adhesive composition for a surface protective substrate film, which is an example of the adhesive composition of the present invention. The adhesive composition for a surface protective substrate film can have the same structure as the aforementioned adhesive composition, and therefore is omitted.

[0158] In addition, the present invention includes an adhesive sheet for surface protection comprising the above-described adhesive layer for surface protection substrate film and the adhesive sheet for surface protection substrate film.

[0159] Therefore, in order to provide the adhesive sheet for surface protection according to the present invention, in addition to including the adhesive composition for surface protection substrate film described above, the composition and manufacturing method commonly used for manufacturing adhesive layers, adhesive films, or adhesive sheets in the same field can be used. As an example, the adhesive layer can be manufactured by coating the adhesive composition for surface protection substrate film of the present invention onto a release film coated with an organosilicon release agent, and the adhesive sheet for surface protection can be manufactured by laminating a PET film onto the adhesive layer formed above.

[0160] In addition, the present invention provides a display comprising the above-described surface protection adhesive sheet. The display of the present invention may include a configuration commonly known in the art, as long as it includes the surface protection adhesive sheet.

[0161] As another example, the adhesive layer manufactured using the adhesive composition of the present invention is more preferably an adhesive layer for a polarizing plate. The aforementioned adhesive layer for a polarizing plate can be formed by coating the adhesive composition onto a release film coated with an organosilicon release agent. The aforementioned adhesive layer for a polarizing plate can be formed using an adhesive composition for a polarizing plate, which is an example of the adhesive composition of the present invention. The adhesive composition for a polarizing plate can have the same composition as the aforementioned adhesive composition, and therefore is omitted. Preferably, the content of the crosslinking agent contained in the aforementioned adhesive composition for a polarizing plate can be from 0.1 parts by weight to 0.5 parts by weight relative to 100 parts by weight of the acrylic copolymer. Preferably, when the content is from 0.1 parts by weight to 0.4 parts by weight, a more suitable adhesive strength can be obtained from the perspective of reworkability.

[0162] Therefore, in order to provide the adhesive layer for polarizing plates of the present invention, in addition to including the adhesive composition described above, the composition and manufacturing methods commonly used for manufacturing adhesive layers, adhesive films, or adhesive sheets in the same field can be used. As an example, the adhesive layer can be manufactured by coating the adhesive composition for polarizing plates of the present invention onto a release film coated with an organosilicon release agent.

[0163] Furthermore, the present invention includes an adhesive sheet for a polarizing plate comprising the aforementioned adhesive layer for a polarizing plate. The aforementioned adhesive sheet for a polarizing plate may further comprise a release film having a lower peel strength than the release film to which the adhesive layer is formed.

[0164] At this time, the polarizing plate including the aforementioned adhesive sheet for polarizing plate can refer to a polarizing plate having an adhesive layer for polarizing plate. That is, a polarizing plate having an adhesive layer for polarizing plate on one side can be bonded to the glass substrate of the optical component after the release film of the adhesive layer is peeled off.

[0165] In addition, the present invention provides a display comprising the above-described adhesive layer for polarizing plates. The display of the present invention may comprise a configuration commonly known in the art, as long as it includes the adhesive layer for polarizing plates of the present invention.

[0166] The following is for reference Figure 1 The embodiments of the present invention will be described in more detail below. However, the accompanying drawings are illustrative of preferred embodiments of the present invention and serve to further illustrate the above-described invention and its technical concept. Therefore, the present invention should not be interpreted solely as described in the drawings.

[0167] Figure 1 This is a diagram illustrating a display comprising a surface protection adhesive sheet and a polarizing plate adhesive layer according to an embodiment of the present invention.

[0168] Reference Figure 1The display of the present invention may include a structure in which a surface protection adhesive sheet 150, 140-1 is included on one side of the polarizing plate 100. The surface protection adhesive sheet 150, 140-1 may be a structure in which an adhesive layer 140-1 for surface protection substrate film is formed on one side of the surface protection substrate film 150.

[0169] The aforementioned surface protective substrate film 150 may include polyethylene terephthalate (PET) film, but is not limited thereto.

[0170] The adhesive layer 140-1 for the surface protective substrate film described above can be applied without limitation to the contents described in the <Adhesive Composition> section above.

[0171] like Figure 1 As shown, the polarizing plate 100 can be a structure in which a protective film 130 is laminated on both sides of the polarizer 110 by an adhesive 120. In addition, it can also be a structure in which the protective film 130 is formed on one side of the polarizer 110 and the other side also includes functional layers such as a phase difference adjustment layer and a refractive index adjustment layer. It can also be a structure in which the phase difference adjustment layer, the refractive index adjustment layer and the protective film are laminated in sequence.

[0172] Therefore, the adhesive force of the surface protection adhesive sheets 150 and 140-1 of the present invention can be less than 1 N / 25 mm, preferably from 0.01 N / 25 mm to 0.9 N / 25 mm.

[0173] The other side of the polarizing plate 100 that does not have surface protection adhesive sheets 150 and 140-1 may contain a polarizing plate adhesive layer 140-2 so that it can be attached to a glass substrate 160 of a liquid crystal cell.

[0174] Reference Figure 1 The display of the present invention may include a polarizing plate adhesive layer 140-2 on one side of the polarizing plate 100 so that it can be attached to a glass substrate 160 or the like of a liquid crystal cell. The polarizing plate adhesive layer 140-2 may be manufactured using a polarizing plate adhesive composition, and more specifically, the contents described in the above-mentioned <adhesive composition> item may be used without limitation.

[0175] like Figure 1 As illustrated, the adhesive composition for polarizing plates of the present invention is preferably used to bond the glass substrate 160 of the liquid crystal cell to the polarizing plate 100. This is because, as described above, excellent adhesion can be ensured to achieve a stable bond between the polarizing plate and the glass, and excellent adhesion is also provided in terms of reworkability when the polarizing plate is subsequently replaced.

[0176] Therefore, the adhesive force of the adhesive layer formed by the adhesive composition for polarizing plates of the present invention can be 1.0 N / 25 mm or more, preferably 1.0 N / 25 mm to 5 N / 25 mm.

[0177] The biomass content of the surface protective substrate film adhesive layer 140-1 and the polarizing plate adhesive layer 140-2 of the present invention, calculated according to ASTM D6866 and Formula 1 below, can be 50% or more.

[0178] <Formula 1>

[0179] Biomass quality (%) = (Number of carbon atoms from biomass source / Total number of carbon atoms) × 100

[0180] The following describes specific embodiments for implementing the present invention, but the present invention is not limited to the following and may be appropriately modified as required in the general field.

[0181] <Synthesis Example 1: Compounds with Chemical Formulas 1-3>

[0182] After decomposing and refining the filling oil to produce 2-octanol, acrylic acid was stirred and refined at 80°C for 3 hours under an acid catalyst to synthesize the product. For the synthesized compounds of formulas 1-3, the biomass content calculated according to formula 1 based on ASTM D6866 is 73%.

[0183] <Synthesis Example 2: Compounds with Chemical Formulas 1-2>

[0184] Bio-butanol (product code: W217816, Sigma-Aldrich) and acrylic acid were synthesized by stirring and purification at 80°C for 3 hours under an acid catalyst. The biomass content of the synthesized compounds of formulas 1-2, calculated according to formula 1 based on ASTM D6866, was 57%.

[0185] <Manufacturing Example: Manufacturing of Acrylic Copolymers>

[0186] Manufacturing Example 1

[0187] In a 1L reactor with nitrogen reflux and a cooling device for easy temperature control, 100 parts by weight of a monomer mixture consisting of 70.8 wt% n-butyl acrylate (BA), 28 wt% methyl acrylate (MA), 0.2 wt% acrylic acid (AA), and 1.0 wt% 2-hydroxyethyl methacrylate (2-HEMA) was added, followed by 100 parts by weight of ethyl acetate (EA) as a solvent. After purging with nitrogen for 1 hour to remove oxygen, the temperature was maintained at 62°C. The mixture was then homogenized, and 0.07 parts by weight of azobisisobutyronitrile (AIBN) was added as a reaction initiator, and the reaction was carried out for 8 hours, thereby producing an acrylic copolymer with a molecular weight of approximately 1.4 million.

[0188] Manufacturing Examples 2 to 4

[0189] The acrylic copolymer was manufactured in the same manner as in Manufacturing Example 1 above, but according to the composition in Table 1 below.

[0190] [Table 1]

[0191]

[0192] Compounds of chemical formulas 1-2: The compounds synthesized in Synthesis Example 2 have a biomass content of 57% according to ASTM D6866 and calculated according to Formula 1;

[0193] Compounds of chemical formulas 1-3: The compounds synthesized in Synthesis Example 1 have a biomass content of 73% according to ASTM D6866 and calculated according to Formula 1;

[0194] BA: Butyl acrylate (Sigma-Aldrich);

[0195] MA: Methyl acrylate (Sigma-Aldrich);

[0196] 2-HMEA: 2-Hydroxyethyl methacrylate (Sigma-Aldrich);

[0197] AA: Acrylic acid (Sigma-Aldrich).

[0198] <Examples and Comparative Examples: Preparation of Adhesive Compositions>

[0199] The adhesive compositions of the manufacturing examples and comparative examples according to the composition in Table 2 below were coated onto a release film coated with an organosilicon release agent and dried at 100°C for 2 minutes to form an adhesive layer with a thickness of 20 μm. Furthermore, an 80 μm PET film treated with corona discharge was laminated onto the above-formed adhesive layer to manufacture a surface protective adhesive sheet (Evaluation I.5, I.6), or a polarizing plate with an adhesive layer was laminated onto the above-formed adhesive layer, with adhesion extending only to the corona-treated triacetyl cellulose (TAC) film, to manufacture a polarizing plate having an adhesive layer (Evaluation II.5, II.6).

[0200] [Table 2]

[0201]

[0202] AH-2100 (Aekyung Chemical): Alicyclic isocyanate;

[0203] D-110N (Mitsui Chemicals): Aromatic isocyanate;

[0204] Crosslinking aid: Sodium 2-ethylhexanoate (Sigma-Aldrich);

[0205] Compound with chemical formula 2-1: HISC-03 (HANIN FINE CHEM);

[0206] Antistatic agent: 1-decylpyridinium bis(fluorosulfonyl)imide.

[0207] <Experimental Example I>

[0208] The physical properties of the adhesive compositions manufactured in Examples I-1 to I-7 and Comparative Examples 1 to 4, the adhesive layers manufactured using them, and the adhesive sheets for surface protection were determined by the following methods, and the results are shown in Table 3 below.

[0209] (I.1) Evaluation of turbidity

[0210] The adhesive compositions of Examples I-1 to I-7 and Comparative Examples 1 to 4 were evaluated by visual inspection to determine whether any cloudiness occurred.

[0211] <Evaluation Criteria>

[0212] ○: There is whitish turbidity;

[0213] ×: No white turbidity.

[0214] (I.2) Biomass quality determination

[0215] For adhesive layers made from the adhesive compositions of Examples I-1 to I-7 and Comparative Examples 1 to 4, the biomass content was calculated according to Formula 1 in accordance with ASTM D6866.

[0216] [Formula 1]

[0217] Biomass quality (%) = (Number of carbon atoms from biomass source / Total number of carbon atoms) × 100

[0218] (I.3) Evaluation of gel fraction

[0219] Approximately 0.25 g of an adhesive layer made from the adhesive compositions of Examples I-1 to I-7 and Comparative Examples 1 to 4 was attached to a 250-mesh wire mesh (100 mm × 100 mm) and wrapped to prevent leakage of the gel components. After weighing (B) using a precision balance, the wire mesh was immersed in an ethyl acetate solution for 3 days. The immersed wire mesh was then removed, washed with a small amount of ethyl acetate solution, dried at 120°C for 24 hours, and its weight was measured (C). The gel fraction was calculated using the measured weight and the following formula 2.

[0220] [Equation 2]

[0221] Gel fraction (%) = (CA) / (BA) × 100

[0222] In the formula, A represents the weight of the wire mesh, B represents the weight of the wire mesh with the adhesive layer attached, and C represents the weight of the wire mesh after impregnation and drying. Therefore, (BA) represents the initial weight of the adhesive layer, and (CA) represents the weight of the gelled adhesive layer.

[0223] (I.4) Maintenance period evaluation

[0224] The adhesive compositions of Examples I-1 to I-7 and Comparative Examples 1 to 4 were cured at 23°C and 50%RH. The gel fraction was measured in days using the same method as the gel fraction evaluation method described in (3) above. The number of days after which the gel fraction no longer increased was measured, i.e., the curing period.

[0225] The curing period is determined based on the time point when the calculated gel fraction value is in the range of 70% to 90% and does not change over time.

[0226] (I.5) Evaluation of the adhesion of adhesive sheets for surface protection

[0227] Surface-protective adhesive sheets manufactured using the adhesive compositions of Examples I-1 to I-7 and Comparative Examples 1 to 4 were cut into lengths of 25 mm and widths of 100 mm. After peeling off the release film, the exposed adhesive layer was attached to a glass substrate (#1737, manufactured by Corning) under a pressure of 0.25 MPa. Test pieces were prepared by autoclaving at 50°C and 5 atmospheres for 20 minutes. To determine the room-temperature adhesion, the prepared test pieces were placed at 23°C and 50% RH for 24 hours. The room-temperature adhesion was determined by peeling the adhesive sheets from the glass substrate using a universal tensile testing machine (UTM, manufactured by Instron) at a peel speed of 300 mm / min and a peel angle of 180°.

[0228] At this point, the room temperature adhesion refers to the initial adhesion after attachment. To verify the phenomenon of increased adhesion during long-term storage or use after attachment, the heating adhesion is confirmed. The heating environment and peeling method are as follows, and are actually confirmed through the evaluation of peeling residue in (I.6).

[0229] To confirm the heat-bonding adhesion, the prepared specimens were placed at 50°C and 50%RH for 48 hours. Then, the bonded sheets were peeled from the glass substrate at 23°C and 50%RH using a universal tensile testing machine (UTM, manufactured by Instron) at a peel speed of 300 mm / min and a peel angle of 180° to confirm the heat-bonding adhesion.

[0230] (I.6) Evaluation of stripping residue

[0231] After evaluating the adhesion using the adhesion evaluation method for the surface protection adhesive sheet described in (I.5), visually confirm the condition of the glass substrate surface to determine whether any residue has been generated.

[0232] <Evaluation Criteria>

[0233] ○: Completely peeled off, with no adhesive residue and the substrate film (PET film) untorn;

[0234] ×: Adhesive residue or tearing of the substrate film (PET film) during peeling.

[0235] [Table 3]

[0236]

[0237] Referring to Table 3 above, it can be confirmed that the surface protection adhesive sheet manufactured using the adhesive compositions of Examples I-1 to I-7 of the present invention has excellent biomass quality, reaching 50% or more, and a gel fraction of 70% or more is obtained at the end of curing. Compared with the adhesive for polarizing plates, it exhibits lower adhesion and can shorten the curing time by adding crosslinking aids.

[0238] More specifically, as an adhesive layer for a surface protection substrate film included in a surface protection adhesive sheet, which simultaneously satisfies an adhesion strength of 1 N / 25 mm or less, preferably 0.01 N / 25 mm to 0.9 N / 25 mm, it not only exhibits very ideal adhesion strength, but also does not produce adhesive residue when the surface protection adhesive sheet is peeled off.

[0239] On the other hand, in the case of Comparative Example 1, which is made with acid, it can be confirmed that although the curing period is very short, it does not contain the monomer represented by Formula 1, and not only is the biomass content 0%, but it is also corrosive to metals, so it is not suitable as an adhesive composition for polarizing plates.

[0240] Furthermore, according to Comparative Examples 2 and 3, since they do not contain acid, the curing period is very long, reaching 30 days, which makes them unsuitable as adhesives for polarizing plates compared to the adhesives in the embodiments of this application.

[0241] In addition, according to Comparative Example 4, although it contains a crosslinking aid, it has poor compatibility with aromatic isocyanates and produces turbidity, so it cannot be used as an adhesive composition for polarizing plates at all.

[0242] <Experimental Example II>

[0243] The physical properties of the adhesive compositions manufactured in Examples II-1 to II-3 and Comparative Examples 1 to 4, the adhesive layers manufactured using them, and the polarizing plates having the adhesive layers were determined by the following methods, and the results are shown in Table 4 below.

[0244] (II.1) Evaluation of turbidity

[0245] (II.2) Determination of biomass quality

[0246] (II.3) Evaluation of gel fraction

[0247] (II.4) Evaluation of the maintenance period

[0248] In the above-mentioned experimental evaluations II.1 to II.4, the adhesive compositions of Examples II-1 to II-3 were used, and the experiments were conducted in the same manner as in experimental evaluations I.1 to I.4.

[0249] (II.5) Evaluation of the adhesion of polarizing plates with adhesive layers

[0250] A polarizing plate having an adhesive layer made from the adhesive compositions of Examples II-1 to II-3 and Comparative Examples 1 to 4 was cut into pieces 25 mm in length and 100 mm in width. After peeling off the release film, the exposed adhesive portion was attached to a glass substrate (#1737, manufactured by Corning) with a pressure of 0.25 MPa. Test pieces were prepared by autoclaving at 50°C and 5 atmospheres for 20 minutes. To determine the room temperature adhesion, the prepared test pieces were placed at 23°C and 50% RH for 24 hours. The room temperature adhesion was determined by peeling the polarizing plate from the glass substrate using a universal tensile testing machine (UTM, manufactured by Instron) at a peel speed of 300 mm / min and a peel angle of 180°.

[0251] At this point, the room temperature adhesion refers to the initial adhesion after attachment. To verify the phenomenon of increased adhesion during long-term storage or use after attachment, the heating adhesion is confirmed. The heating environment and peeling method are as follows, and are actually confirmed through (II.6) reworkability evaluation.

[0252] To confirm the heat adhesion, the prepared specimens were placed at 50°C and 50%RH for 48 hours. Then, the polarizing plate was peeled from the glass substrate at a peel speed of 300 mm / min and a peel angle of 180° using a universal tensile testing machine (UTM, manufactured by Instron) at 23°C and 50%RH to confirm the heat adhesion.

[0253] (II.6) Reworkability Assessment

[0254] After evaluating the adhesion using the adhesion evaluation method for polarizing plates with adhesive layers described above (II.5), visually confirm the condition of the glass substrate surface to determine whether there are any adhesive residues remaining from the polarizing plate.

[0255] <Evaluation Criteria>

[0256] ○: Completely peeled off, no residue;

[0257] ×: Residue remains.

[0258] (II.7) Evaluation of Metal Corrosion

[0259] Aluminum foil was adhered to an adhesive layer made from the adhesive compositions of Examples II-1 to II-3 and Comparative Examples 1 to 4, and the corrosivity was observed when the aluminum foil was subjected to autoclave treatment for 20 minutes at 50°C and 5 atmospheres, and then placed at 85°C and 85% relative humidity for 15 days.

[0260] <Evaluation Criteria>

[0261] ○: The aluminum foil remains unchanged;

[0262] ×: The aluminum foil has changed color.

[0263] [Table 4]

[0264]

[0265] Referring to Table 4 above, it can be confirmed that the adhesive layer manufactured using the adhesive compositions of Examples II-1 to II-3 of the present invention has excellent biomass content, reaching 50% or more. Since it simultaneously satisfies an adhesion strength of 1.0 N / 25 mm or more, preferably 1.0 N / 25 mm to 5 N / 25 mm, it not only possesses ideal adhesion strength as an adhesive for polarizing plates, but also, because it does not contain acid, it is not corrosive to metals. Even when manufactured without acid, the curing period is shortened by more than 50% compared to other comparative examples that do not contain acid. Furthermore, despite the high adhesion strength, it exhibits excellent reworkability, and no residue is generated on the glass substrate surface even during separation.

[0266] On the other hand, in the case of Comparative Example 1, which is made with acid, it can be confirmed that although the curing period is very short, it does not contain the monomer represented by Formula 1, and not only is the biomass content 0%, but it is also corrosive to metals, so it is not suitable as an adhesive composition for polarizing plates.

[0267] Furthermore, according to Comparative Examples 2 and 3, since they do not contain acid, the curing period is very long, reaching 30 days, which is not suitable as an adhesive for polarizing plates compared with the adhesive of the embodiments of this application.

[0268] In addition, according to Comparative Example 4, although it contains a crosslinking aid, it has poor compatibility with aromatic isocyanates and produces turbidity, so it cannot be used as an adhesive composition for polarizing plates at all.

Claims

1. An adhesive composition comprising: an acrylic copolymer polymerized from a compound represented by the following chemical formula 1; and a crosslinking agent, The crosslinking agent is selected from one or more of isocyanate compounds, epoxy compounds, oxazoline compounds, aziridine compounds, and metal chelate compounds, and the isocyanate compound is selected from at least one of aliphatic isocyanate compounds and alicyclic isocyanate compounds. Chemical Formula 1 In the chemical formula 1, R1 is hydrogen or methyl. R2 is a hydrocarbon group derived from biomass with 1 to 100 carbon atoms.

2. The adhesive composition according to claim 1, wherein the adhesive composition is an adhesive composition for polarizing plates.

3. The adhesive composition according to claim 2, wherein the crosslinking agent content is from 0.1 parts by weight to 0.4 parts by weight relative to 100 parts by weight of the acrylic copolymer.

4. The adhesive composition according to claim 2, wherein the adhesive force of the adhesive layer formed by the adhesive composition is more than 1 N / 25 mm and less than 5 N / 25 mm.

5. The adhesive composition according to any one of claims 1 to 4, wherein the adhesive composition is an adhesive composition for surface protective substrate films.

6. The adhesive composition according to claim 5, wherein the crosslinking agent content is from 0.5 parts by weight to 2.5 parts by weight relative to 100 parts by weight of the acrylic copolymer.

7. The adhesive composition according to claim 5, wherein the adhesive sheet formed from the adhesive composition has an adhesion force of 1 N / 25 mm or less.

8. The adhesive composition according to any one of claims 1 to 4, further comprising a crosslinking aid.

9. The adhesive composition according to claim 8, wherein the crosslinking aid is one or more selected from sodium salt series, calcium salt series and tin series compounds.

10. The adhesive composition according to claim 8, wherein the crosslinking aid is present in an amount of 0.01 parts by weight to 0.1 parts by weight relative to 100 parts by weight of the acrylic copolymer.

11. The adhesive composition according to any one of claims 1 to 4, wherein the content of the compound represented by chemical formula 1 is 30 to 80 by weight relative to the total weight of monomers used in the polymerization of the acrylic copolymer.

12. The adhesive composition according to any one of claims 1 to 4, wherein the acrylic copolymer does not contain acidic functional groups.

13. The adhesive composition according to any one of claims 1 to 4, further comprising one or more silane coupling agents selected from the group consisting of compounds represented by chemical formula 2. Chemical formula 2 In the chemical formula 2, R8 is an alkyl group having 1 to 12 carbon atoms or an alkoxy group having 1 to 12 carbon atoms. R9 is a divalent aliphatic hydrocarbon group with 1 to 30 carbon atoms. R 10 To R 12 Each of them is independently hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms.

14. The adhesive composition according to claim 13, wherein the content of the silane coupling agent is 0.01 to 3 parts by weight relative to 100 parts by weight of the acrylic copolymer.

15. The adhesive composition according to any one of claims 1 to 4, wherein the biomass content of the adhesive layer formed by said adhesive composition, calculated according to ASTM D6866 and Formula 1, is 50% or more. Formula 1 Biomass quality (%) = Number of carbon atoms from biomass source / Total number of carbon atoms × 100.

16. The adhesive composition according to any one of claims 1 to 4, wherein the adhesive composition further comprises one or more of the group selected from the group consisting of antistatic agents, surfactants, adhesion promoters and anti-coagulants.

17. An adhesive layer comprising the adhesive composition of any one of claims 1 to 16.

18. An adhesive sheet comprising the adhesive layer of claim 17 and a substrate film.

19. A display comprising the adhesive sheet of claim 18.

Images