Adhesive composition, adhesive sheet, and display containing the same

Abstract

The present invention relates to an adhesive composition, an adhesive sheet manufactured using the same, and a display containing the same, and provides an environmentally friendly adhesive composition, an adhesive sheet manufactured using the same, and a display containing the same, which can provide appropriate tackiness without a decrease in gel fraction even without containing an acid component, does not generate residue, prevents an excessive increase in curing time. [Solution] An adhesive composition is provided, comprising an acrylic copolymer polymerized with biomass-derived acrylic monomers, and a crosslinking agent, wherein the crosslinking agent is one or more selected from at least one isocyanate compound selected from aliphatic isocyanate compounds and alicyclic isocyanate compounds, epoxy compounds, oxazoline compounds, aziridine compounds, and metal chelate compounds.

Description

[Technical Field]

[0001] The present invention relates to an adhesive composition, an adhesive sheet manufactured using the same, and a display containing the same. [Background technology]

[0002] An image display device consists of a liquid crystal cell containing liquid crystal and a polarizing plate, which are mainly bonded by forming an adhesive layer on one side of the polarizing plate. In this case, the polarizing plate has a polarizer that performs the polarizing function, and a triacetylcellulose (TAC) film attached to one or both sides as a protective film to protect the polarizer. In order to improve the function of the liquid crystal display device, protective films such as a phase difference plate, a wide viewing angle compensation plate, and a brightness enhancement plate can be attached in place of the triacetylcellulose (TAC) film that serves a general protective purpose.

[0003] On the other hand, adhesive layers are used in various applications in such image display devices. For example, in the manufacturing process of optical components, surface protection adhesive sheets are attached to optical components such as polarizers and phase difference plates to prevent surface scratches. Such surface protection adhesive sheets have a structure in which an adhesive layer for the surface protection substrate film is applied to a surface protection substrate film. The adhesive used to bond the surface protection substrate film requires a lower adhesive strength than adhesives used in ordinary optical components so that it can be easily peeled off. In the case of surface protection adhesive sheets without acid components, the gel fraction decreases, the adhesive strength increases excessively, and there is a problem that the function as a surface protection film is insufficient, resulting in an excessively long curing time.

[0004] As another example, when a polarizing plate is bonded to an optical component such as a liquid crystal cell, the polarizing plate may need to be peeled off from the optical component for various reasons and then reattached. In such cases, the adhesive layer for the polarizing plate, which is provided to bond the polarizing plate to the liquid crystal cell, is required to be easily detachable from the liquid crystal cell while maintaining its adhesive strength (reworkability).

[0005] On the other hand, in the case of adhesives containing acid, the acid component may cause corrosion of the metal layer of the optical component to be adhered, thus necessitating an acid-free adhesive. However, removing the acid from the adhesive composition leads to an excessive increase in adhesive strength, making it difficult to separate the optical component. Furthermore, since the aforementioned adhesives are manufactured using petrochemical products derived from the petroleum separation and refining process, such petrochemical products could incur enormous environmental costs under international agreements that strictly regulate greenhouse gas emissions. Therefore, the development of environmentally friendly materials that can replace existing petrochemical products is progressing.

[0006] Korean Published Patent No. 10-2020-0025044 discloses an adhesive composition that does not contain acidic functional groups, but it has the problem of having excessive adhesive and peeling strength, making it difficult to apply to surface protective substrate films and still not being able to provide environmental friendliness. Korean Registered Patent No. 10-5694629 discloses an adhesive film that does not require a curing period after application, but the resin composition of the adhesive contains acidic compounds and does not take into consideration the metal layer, so corrosion may occur due to the migration of acidic components, and it still has the problem of being insufficient for use in polarizing plates, especially as an adhesive composition for polarizing plates used to bond optical members and polarizing plates. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Korean Published Patent No. 10-2020-0025044 [Patent Document 2] Korean Registered Patent No. 10-5694629 [Overview of the project] [Problems that the invention aims to solve]

[0008] The present invention aims to solve the problems of the prior art described above, and provides an adhesive composition that minimizes the decrease in gel fraction by not containing acid components, provides adhesiveness suitable for the application in bonding and / or adhesion to optical components, has good adhesion to the substrate, does not generate residue on the adherend when separated and / or peeled off, and prevents an excessive increase in curing time.

[0009] Furthermore, the present invention aims to provide an adhesive composition that not only prevents the occurrence of clouding and corrosion of the adherend, but also offers environmental friendliness.

[0010] Furthermore, the present invention aims to provide an adhesive sheet, an adhesive layer with excellent reworkability, and a display containing the same, which are environmentally friendly, can prevent corrosion of the adherend, and provide appropriate tackiness so that no residue is generated on the adherend during separation and / or peeling, thereby being suitable for temporary adhesion to protect the surface of the adherend.

[0011] However, the problems that this application aims to solve are not limited to those mentioned above, and other problems not mentioned should be clearly understandable to an average engineer from the description below. [Means for solving the problem]

[0012] To achieve the above objective, the present invention provides an acrylic copolymer polymerized with a compound represented by the following chemical formula 1; and a crosslinking agent, wherein the crosslinking agent is one or more adhesive compositions selected from at least one isocyanate compound selected from aliphatic isocyanate compounds and alicyclic isocyanate compounds, epoxy compounds, oxazoline compounds, aziridine compounds, and metal chelate compounds.

[0013] [Chemical formula 1] JPEG2026139557000002.jpg33170

[0014] (In the above chemical formula 1, R1 is hydrogen or a methyl group, R2 is a hydrocarbon group derived from biomass having 1 to 100 carbon atoms.)

[0015] The pressure-sensitive adhesive composition may be a pressure-sensitive adhesive composition for polarizing plates.

[0016] The crosslinking agent may be contained in an amount of 0.1 part by weight to 0.4 part by weight relative to 100 parts by weight of the acrylic copolymer.

[0017] The pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition may have an adhesive strength of 1 N / 25 mm or more and 5 N / 25 mm or less.

[0018] The pressure-sensitive adhesive composition may be a pressure-sensitive adhesive composition for surface protective base films.

[0019] The crosslinking agent may be contained in an amount of 0.5 part by weight to 2.5 parts by weight relative to 100 parts by weight of the acrylic copolymer.

[0020] The pressure-sensitive adhesive sheet formed from the pressure-sensitive adhesive composition may have an adhesive strength of 1 N / 25 mm or less.

[0021] The pressure-sensitive adhesive composition may further contain a crosslinking auxiliary.

[0022] The crosslinking auxiliary is a sodium salt (Na + ) series, calcium salt (Ca 2+ ) series and tin (Sn) series compounds, and may be one or more selected from the group consisting of the above.

[0023] The crosslinking auxiliary may be contained in an amount of 0.01 part by weight to 0.1 part by weight relative to 100 parts by weight of the acrylic copolymer.

[0024] The compound represented by the above Chemical Formula 1 may be contained in an amount of 30 to 80% by weight relative to the total weight of the monomers used for polymerization of the acrylic copolymer.

[0025] The aforementioned acrylic copolymer may not contain acidic functional groups.

[0026] The adhesive composition may further contain one or more silane coupling agents selected from the group consisting of compounds represented by the following chemical formula 2.

[0027] [Chemical formula 2] JPEG2026139557000003.jpg29170

[0028] (In the above 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 having 1 to 30 carbon atoms. R 10 R 12 These are, independently, hydrogen, a C1-C12 alkyl group, a C2-C12 alkenyl group, a C2-C12 alkynyl group, or a C1-C12 alkoxy group.

[0029] The silane coupling agent may be present in an amount of 0.01 to 3 parts by weight per 100 parts by weight of the acrylic copolymer.

[0030] The adhesive layer formed with the adhesive composition may have a biomass content of 50% or more, calculated by the following formula 1 in accordance with ASTM D6866.

[0031] [Formula 1] Biomass percentage (%) = Number of carbon atoms from biomass / Total number of carbon atoms × 100

[0032] The adhesive composition may further contain one or more selected from the group consisting of antistatic agents, surfactants, adhesion promoters, and anti-aggregation agents.

[0033] Furthermore, the present invention relates to an adhesive layer containing the adhesive composition.

[0034] Furthermore, the present invention relates to an adhesive sheet comprising the adhesive layer and the base film.

[0035] Furthermore, the present invention relates to a display including the adhesive sheet. [Effects of the Invention]

[0036] The present invention provides an adhesive composition that can provide appropriate tackiness, has good adhesion to the substrate, and leaves no residue on the adherend when separated and / or peeled off, thereby satisfying desirable adhesive properties for polarizing plates and / or optical components.

[0037] Furthermore, the present invention prevents excessive increases in curing time, prevents clouding and corrosion of the metal layer of the liquid crystal cell, and provides an environmentally friendly adhesive composition by including an acrylic copolymer polymerized by mixing a monomer derived from biomass.

[0038] Furthermore, the present invention can minimize the decrease in gel fraction even without containing acidic components, provide appropriate tackiness, and leave no residue on the adherend when peeled off, thus providing an adhesive composition for surface protection substrate films that is suitable for temporary adhesion for surface protection of the adherend.

[0039] Furthermore, the present invention can provide appropriate adhesion to the glass substrate of an optical component when bonding a polarizing plate to another optical component, and leaves no residue on the optical component when separated from the polarizing plate. Therefore, it can provide an adhesive composition for polarizing plates that is suitable in terms of both fixing strength and reworkability when bonding to a polarizing plate.

[0040] Furthermore, the present invention can provide an adhesive sheet and a display containing the same that are environmentally friendly and offer appropriate adhesive properties. [Brief explanation of the drawing]

[0041] [Figure 1]Figure 1 shows a display including a surface protection adhesive sheet and a polarizing plate adhesive layer according to one embodiment of the present invention. [Modes for carrying out the invention]

[0042] The present invention relates to an adhesive composition, an adhesive sheet, and a display containing the same, which satisfies a biomass content of 50% or more calculated in accordance with ASTM D6866, while also containing at least one isocyanate compound selected from aliphatic isocyanate compounds and alicyclic isocyanate compounds, an epoxy compound, an oxazoline compound, an aziridine compound, and a metal chelate compound as a crosslinking agent, thereby providing appropriate tackiness, good adhesion to the substrate, and no residue left on the adherend when peeled off, thus satisfying desirable tackiness for polarizers and / or optical components. The adhesive composition can provide suitable tackiness for laminates containing optical components such as polarizers and liquid crystal cells, depending on the application.

[0043] Furthermore, because the adhesive composition of the present invention does not contain acidic components, it does not cause clouding, does not cause corrosion to metal layers such as ITO, and despite not containing acidic components, it may be possible to shorten the curing period.

[0044] Biomass is a general term for living organisms such as plants that synthesize organic matter using solar energy, and animals and microorganisms that feed on them, and includes secondary products and waste derived from these living organisms. The compounds derived from the biomass are radioactive carbon isotopes that are present only in naturally occurring materials. 14 C) contains radioactive carbon isotopes ( 14 It is distinguished from petroleum-derived compounds that do not contain C).

[0045] At this time, the biomass content of the adhesive sheet formed with the adhesive composition is determined by the radioactive carbon isotopes contained in the adhesive composition.14 While it is possible to calculate the biomass content by measuring the concentration of C), measuring biomass content requires requesting services from a testing institution capable of measuring radioactive isotopes, which may be quite costly and time-consuming.

[0046] Therefore, the biomass content of the adhesive composition, adhesive layer, and adhesive sheet containing the same of the present invention may be calculated by the following formula 1 in accordance with ASTM D6866, and the biomass content calculated in this way may be 50% or more.

[0047] [Formula 1] Biomass percentage (%) = Number of carbon atoms from biomass / Total number of carbon atoms × 100

[0048] The present invention will be described in more detail below. However, the terms used herein are for illustrative purposes only and do not limit the present invention. In this specification, adhesive sheet may include an adhesive layer and a film. Specifically, in this specification, a surface protection adhesive sheet includes an adhesive layer for a surface protection substrate film and a surface protection substrate film.

[0049] <Adhesive composition> The adhesive composition of the present invention comprises an acrylic copolymer polymerized with a compound of chemical formula 1, which is a monomer derived from biomass, and a crosslinking agent for preventing a decrease in gel fraction without containing an acid component. It may further contain a crosslinking aid that can further shorten the curing time, a silane coupling agent having a triethoxysilane group, and, if necessary, one or more selected from the group consisting of surfactants, adhesion promoters, and anti-flocculation agents.

[0050] Acrylic copolymer The acrylic copolymer contained in the adhesive composition of the present invention is polymerized with a monomer derived from biomass, and is characterized by containing an acrylic copolymer polymerized with a compound represented by the following chemical formula 1.

[0051] <Chemical formula 1> JPEG2026139557000004.jpg34170

[0052] In the above chemical formula 1, R1 is a hydrogen or methyl group, and R2 is a biomass-derived hydrocarbon group having 1 to 100 carbon atoms.

[0053] The aforementioned biomass-derived hydrocarbon groups are not particularly limited as long as they originate from biomass, that is, from living organisms such as plants that synthesize organic matter using solar energy, and animals and microorganisms that feed on them. They can be obtained cheaply and easily by using saturated and unsaturated fatty acids extracted from living organisms such as plants and animals as raw materials and then alcoholizing and esterifying them.

[0054] The biomass-derived hydrocarbon groups of the present invention may include saturated or unsaturated hydrocarbon groups, and may include cyclic or alicyclic hydrocarbon groups.

[0055] The saturated or unsaturated chain hydrocarbon group may be a linear or branched chain, and examples include alkyl groups and alkenyl groups.

[0056] The saturated or unsaturated alicyclic hydrocarbon groups include monocyclic and polycyclic alicyclic hydrocarbon groups, such as cycloalkyl groups, cycloalkenyl groups containing double bonds, and adamantyl groups.

[0057] Furthermore, the hydrocarbon group may include a combination of saturated or unsaturated chain-like or alicyclic hydrocarbon groups. Examples include combinations of alkyl groups and alkenyl groups, alkyl groups and cycloalkyl groups, alkyl groups and cycloalkenyl groups, and cycloalkyl groups and cycloalkenyl groups.

[0058] More specifically, the compound represented by chemical formula 1 may include one or more compounds selected from the group consisting of compounds represented by the following chemical formulas 1-1 to 1-3.

[0059] <Chemical formula 1-1> JPEG2026139557000005.jpg19170

[0060] <Chemical formula 1-2> JPEG2026139557000006.jpg21170

[0061] <Chemical formula 1-3> JPEG2026139557000007.jpg35170

[0062] The compound represented by chemical formula 1 may be present in an amount of 30 to 80% by weight relative to the total weight of the monomers used in the polymerization of the acrylic copolymer. When this content range is satisfied, the desired biomass content can be achieved, and there is an advantage in being able to provide an environmentally friendly adhesive composition.

[0063] The acrylic copolymer of the present invention may further contain an acrylic monomer that does not contain an acidic functional group other than the compound represented by chemical formula 1 described above. Examples of the acidic functional group include a carboxyl group, a sulfonic acid group, or a phosphate group. When a monomer containing such a group is used, corrosion may occur when used on a metallic substrate.

[0064] The acrylic monomer that does not contain an acidic functional group may, for example, be polymerized by further including one or more selected from the group consisting of alkyl (meth)acrylate, hydroxyl group-containing monomer, amide group-containing monomer, amino group-containing monomer, imide group-containing monomer, epoxy group-containing monomer, and ether group-containing monomer.

[0065] The alkyl (meth)acrylate is not particularly limited, and the term "(meth)acrylate" means either acrylate or methacrylate.

[0066] Specific examples of the alkyl(meth)acrylates mentioned above include methyl(meth)acrylate, ethyl(meth)acrylate, n-propyl(meth)acrylate, isopropyl(meth)acrylate, n-butyl(meth)acrylate, sec-butyl(meth)acrylate, t-butyl(meth)acrylate, isobutyl(meth)acrylate, pentyl(meth)acrylate, hexyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, n-octyl(meth)acrylate, isooctyl(meth)acrylate, n-nonyl(meth)acrylate, isononyl(meth)acrylate, n-decyl(meth)acrylate, isodecyl(meth)acrylate, n-dodecyl(meth)acrylate, n-tridecyl(meth)acrylate, n-tetradecyl(meth)acrylate, and phenoxyethyl(meth)acrylate.

[0067] The alkyl (meth)acrylate may be present in an amount of 10 to 70% by weight relative to the total weight of the monomers used in the polymerization of the acrylic copolymer, and when this content range is satisfied, it is preferable from the viewpoint of improving adhesiveness and durability.

[0068] Examples of the hydroxyl group-containing monomers 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-hydroxylauryl (meth)acrylate, (4-hydroxymethylcyclohexyl)methyl acrylate, N-methylol (meth)acrylamide, vinyl alcohol, allyl alcohol, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, diethylene glycol monovinyl ether, and 2-acryloyloxyethyl-2-hydroxyethyl phthalate.

[0069] Examples of the amide group-containing monomers 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.

[0070] Examples of the amino group-containing monomers include N,N-(dimethylamino)ethyl (meth)acrylate, N,N-(diethylamino)ethyl (meth)acrylate, and N,N-(dimethylamino)propyl (meth)acrylate, while examples of the imide group-containing monomers include cyclohexylmaleimide and isopropylmaleimide.

[0071] Examples of the epoxy group-containing monomer include glycidyl (meth)acrylate and methylglycidyl (meth)acrylate, and examples of the ether group-containing monomer include 3-methoxybutyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 3-methoxypropyl (meth)acrylate, 2-methoxybutyl (meth)acrylate, methoxypolyethylene glycol acrylate with an addition number of oxyethylenes in the range of 1 to 15, ethoxy-diethylene glycol (meth)acrylate, and ethyl carbitol (meth)acrylate.

[0072] The acrylic copolymer may further contain other monomers commonly used in the art to which the present invention belongs, in addition to the monomers, within a range that does not reduce the adhesiveness. For example, it may further contain 10% by weight or less of the total weight of the monomers used in the polymerization of the acrylic copolymer.

[0073] The acrylic copolymer may have a weight-average molecular weight (polystyrene equivalent; Mw) of 500,000 to 2,000,000 as measured by gel permeation chromatography (GPC), and more preferably 700,000 to 1,700,000. If the weight-average molecular weight of the acrylic copolymer is less than 500,000, the chain structure in the adhesive film after UV polymerization and curing is simple and short, which is disadvantageous from a reliability standpoint, such as the generation of bubbles, and may lead to a decrease in durability due to discoloration, etc. If it exceeds 2,000,000, the viscosity of the adhesive resin composition is excessively high during the production of the adhesive film, requiring a large amount of monomer dilution to match the appropriate viscosity required for production, which may require high energy during UV polymerization and curing, or may result in the retention of unreacted monomers.

[0074] The method for producing the acrylic copolymer is not particularly limited. For example, methods commonly used in the art to which the present invention belongs, such as bulk polymerization, solution polymerization, emulsion polymerization, suspension polymerization, and UV polymerization, may be used, and preferably, solution polymerization or UV polymerization may be used.

[0075] The acrylic copolymer of the present invention is preferable from the viewpoint of corrosion resistance because it is substantially acid-free. Being substantially acid-free means that the acid value of the acrylic copolymer is usually 1 mg KOH / g or less, preferably 0.5 mg KOH / g or less, and particularly preferably 0.

[0076] Crosslinking agent The adhesive composition of the present invention contains a crosslinking agent to strengthen intermolecular bonds, and the crosslinking agent may include at least one isocyanate compound selected from aliphatic isocyanate compounds and alicyclic isocyanate compounds, one or more selected from epoxy compounds, oxazoline compounds, aziridine compounds and metal chelate compounds.

[0077] Since the aforementioned acrylic copolymer does not contain acidic functional groups, the gel fraction is significantly reduced. However, when the aforementioned crosslinking agent is included, it is possible to prevent an excessive reduction in the gel fraction, provide sufficient adhesive strength to act as an adhesive, and offer an appropriate gel fraction and reworkability so that no residue is left when separating from and / or peeling off the adherend.

[0078] The at least one isocyanate compound selected from the aliphatic isocyanate compounds and alicyclic isocyanate compounds is a compound containing one or more isocyanate groups (-N=C=O) per molecule, and may contain isocyanurate groups, biuret groups, allophanate groups, oxadiazinetrione groups, urea groups, and urethane groups, and it is preferable from the viewpoint of viscosity adjustment that the final structure does not contain an aromatic ring.

[0079] The aliphatic isocyanate compounds and alicyclic isocyanate compounds are not particularly limited, but include, but are not limited to, hexamethylene 1,6-diisocyanate (HDI), tetramethylene diisocyanate 4-isocyanatomethyl-1,8-octamethylene diisocyanate (trimeric triisocyanate), pentamethylene diisocyanate, 2,2,4-trimethyl-1,6-diisocyanatohexane, lysine diisocyanate, hexamethylene diisocyanate isocyanurate, 4,4'-methylenebis(cyclohexyl isocyanate), and isophorone diisocyanate.

[0080] Examples of the epoxy crosslinking agents include ethylene glycol diglycidyl ether, triglycidyl ether, trimethylolpropane triglycidyl ether, N,N,N',N'-tetraglycidylethylenediamine, and glycerin diglycidyl ether. These may be used individually or in combination of two or more.

[0081] Examples of the oxazoline-based crosslinking agents include copolymers polymerized with at least one monomer containing an 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 may be used individually or in combination of two or more.

[0082] Examples of the aforementioned aziridine crosslinking agents include N,N'-toluene-2,4-bis(1-aziridinecarboxamide), N,N'-diphenylmethane-4,4'-bis(1-aziridinecarboxamide), triethylenemelamine, bisisophthaloyl-1-(2-methylaziridine), and tri-1-aziridinylphosphine oxide. These may be used individually or in combination of two or more.

[0083] Examples of the aforementioned metal chelating crosslinking agents include compounds in which polyvalent metals such as aluminum, iron, zinc, tin, titanium, antimony, magnesium, and / or vanadium are coordinated to acetylacetone or ethyl acetoethyl acetate. These may be used individually or in combination of two or more.

[0084] In the present invention, the crosslinking agent may 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 may be used in combination.

[0085] The crosslinking agent may be present in an amount of 0.1 to 2.5 parts by weight, preferably 0.1 to 1.0 part by weight, per 100 parts by weight of the acrylic copolymer. If the amount of crosslinking agent exceeds the above range, the adhesive strength may decrease excessively, resulting in poor adhesion. If the amount of crosslinking agent does not reach the above range, the crosslinking reaction may not proceed sufficiently, resulting in insufficient cohesive force, and insufficient increase in adhesive strength and durability.

[0086] Furthermore, by adjusting the content of the crosslinking agent, the adhesive composition of the present invention can be manufactured to provide adhesive strength suitable for various applications in laminates containing optical components such as polarizing plates and liquid crystal cells.

[0087] For example, when manufacturing a surface protection adhesive sheet suitable for temporary adhesion to protect the surface of a substrate, in the adhesive composition for a surface protection substrate film for manufacturing the surface protection adhesive sheet, the crosslinking agent may be contained in an amount of 0.5 to 2.5 parts by weight, preferably 0.5 to 1.0 part by weight, per 100 parts by weight of the acrylic copolymer, and when the above content range is satisfied, it is preferable from the viewpoint of ensuring the gel fraction in the initial curing stage.

[0088] As another example, when forming an adhesive layer for a polarizing plate that has the property of being easily separated when bonding the polarizing plate and liquid crystal cell, while maintaining adhesive strength (reworkability), in the adhesive composition for polarizing plates for manufacturing the adhesive layer for polarizing plates, the crosslinking agent may be included in an amount of 0.1 to 0.5 parts by weight per 100 parts by weight of acrylic copolymer, and preferably in an amount of 0.1 to 0.4 parts by weight from the viewpoint of durability and shortening the curing time. When the above content range is satisfied, adhesive strength can be ensured by appropriate crosslinking and, if acid is not present, the required curing period can be shortened by 50% or more.

[0089] Crosslinking aid The adhesive composition of the present invention may further contain a crosslinking aid to improve the gel fraction through an additional improvement in the degree of crosslinking.

[0090] Said crosslinking auxiliary agent is a sodium salt (Na + ) type, calcium salt (Ca 2+ ) type and tin (Sn) type compounds. One or more selected from the above may be used. Examples include, but are not limited to, Sodium 2-ethylhexanoate, Sodium ricinoleate, Calcium 2-ethylhexanoate, Dibutyltin dilaurate, and the like.

[0091] By including said crosslinking auxiliary agent, the decreased gel fraction caused by not incorporating an acid component into the acrylic copolymer contained in the adhesive composition can be further improved, and the curing period of the adhesive can be shortened.

[0092] Said crosslinking auxiliary agent may be contained in an amount of 0.01 part by weight to 0.1 part by weight, preferably 0.02 part by weight to 0.08 part by weight, relative to 100 parts by weight of the acrylic copolymer. When the content satisfies the above range, it is preferable from the viewpoint of accelerating the increase of gel fraction and shortening the curing period.

[0093] Silane coupling agent The adhesive composition of the present invention may further include one or more silane coupling agents selected from the group consisting of compounds represented by the following Chemical Formula 2.

[0094] The one or more silane coupling agents selected from the group consisting of compounds represented by said Chemical Formula 2 can improve the compatibility of the adhesive composition, enhance adhesive strength, and suppress the generation of air bubbles, lifting and breakage in the adhesive layer.

[0095] Said silane coupling agent may contain a nitrogen atom or a sulfur atom, and in this case, it can provide adhesive durability and reliability even when left standing for a long time under heat-resistant and moisture-heat-resistant conditions.

[0096] <Chemical formula 2> JPEG2026139557000008.jpg29170

[0097] In the above chemical formula 2, R8 is an alkyl group having 1 to 12 carbon atoms or an alkoxy group having 1 to 12 carbon atoms, and R9 is a divalent aliphatic hydrocarbon having 1 to 30 carbon atoms. 10 R 12 These are, 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.

[0098] Specifically, it is preferable that the silane coupling agent has a trimethoxysilane group in order to achieve the objectives and effects of the present invention.

[0099] The compound represented by chemical formula 2 may, for example, be the compound represented by chemical formula 2-1 below.

[0100] <Chemical formula 2-1> JPEG2026139557000009.jpg14170

[0101] The silane coupling agent may be present in an amount of 0.01 to 3 parts by weight, preferably 0.1 to 2 parts by weight, per 100 parts by weight of the acrylic copolymer. Within this range, the durability and adhesion of the adhesive layer formed from the adhesive composition can be improved.

[0102] additives The adhesive composition may further contain, as necessary, conventional additives known in the art to adjust the adhesive strength, cohesive force, viscosity, modulus of elasticity, glass transition temperature, etc., required for the application. For example, it may contain one or more selected from the group consisting of antistatic agents, surfactants, adhesion promoters, and anti-coagulation agents.

[0103] The adhesive composition of the present invention may further contain an antistatic agent, which may be an ionic antistatic agent and may contain an ionic salt composed of anions and cations, thereby imparting ionic conductivity to the adhesive layer formed from the adhesive composition of the present invention.

[0104] The ionic antistatic agent may include an alkali metal salt, an ionic liquid, or an ionic solid, and preferably may include an ionic solid.

[0105] By including an ionic solid as an ionic antistatic agent, the aging stability and durability of the adhesive layer of the adhesive composition of the present invention can be improved. Furthermore, the ionic solid has high compatibility with the other components mentioned above, and the transparency of the adhesive composition of the present invention can be maintained at a high level.

[0106] The cation of the ionic solid may include imidazolium, pyridinium, alkylammonium, alkylpyrrolidinium, and / or alkylphosphonium.

[0107] In some embodiments, the content of the ionic antistatic agent may be 0.01 to 5 parts by weight per 100 parts by weight of the acrylic copolymer. Within this range, the antistatic properties of the adhesive layer can be improved while maintaining excellent durability of the adhesive layer.

[0108] To further improve film formation, the adhesive composition of the present invention may contain surfactants, and preferably, silicone-based, fluorine-based, ester-based, cationic, anionic, nonionic, and amphoteric surfactants may be used.

[0109] Examples of the aforementioned silicone-based surfactants include commercially available products such as DC3PA, DC7PA, SH-11PA, SH-21PA, and SH-8400 from Toray Dow Corning Silicone Co., Ltd., and TSF-4440, TSF-4300, TSF-4445, TSF-4446, TSF-4460, and TSF-4452 from GE Toshiba Silicone Co., Ltd.

[0110] Examples of the aforementioned fluorine-based surfactants include commercially available products such as MEGAFACE F-470, F-471, F-475, F-482, F-489, and F-554 manufactured by Dainippon Ink and Chemicals, Inc.

[0111] Other commercially available products that can be used include KP (Shin-Etsu Chemical Co., Ltd.), POLYFLOW (Kyoeisha Chemical Co., Ltd.), EFTOP (Tochem Products), MEGAFAC (Dainippon Ink and Chemicals, Inc.), Flourad (Sumitomo 3M Limited), Asahi Guard, Surflon (all from Asahi Glass Co., Ltd.), SOLSPERSE (Lubrisol), EFKA (EFKA Chemicals), PB821 (Ajinomoto Co., Inc.), and DISPERBYK-series (BYK-chemi).

[0112] The surfactants described above can be used individually or in combination of two or more, and may be included in amounts of 0.01 to 5 parts by weight, preferably 0.05 to 2 parts by weight, per 100 parts by weight of the adhesive composition.

[0113] The adhesive composition of the present invention may contain an adhesion promoter to enhance adhesion, which is typically 0.01 to 5 parts by weight, preferably 0.05 to 2 parts by weight, per 100 parts by weight of the adhesive composition.

[0114] The type of adhesion promoter is not particularly limited, and specific examples of usable adhesion promoters include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(2-methoxyethoxy)silane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-chloropropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, 3-methacrylateoxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-isocyanatetopropyltrimethoxysilane, and 3-isocyanatetopropyltriethoxysilane.

[0115] The type of anti-flocculation agent is not particularly limited, but specific examples of usable agents include sodium polyacrylate, which may be included in amounts of 0.01 to 5 parts by weight, preferably 0.05 to 2 parts by weight, per 100 parts by weight of the adhesive composition.

[0116] <Adhesive layers, adhesive sheets, and displays> The present invention extends to adhesive layers, adhesive sheets, and displays containing the same, manufactured using the adhesive composition described above. In particular, the adhesive layer manufactured using the adhesive composition of the present invention may have a biomass content of 50% or more, calculated by the following formula 1 in accordance with ASTM D6866.

[0117] <Expression 1> Biomass percentage (%) = Number of carbon atoms from biomass / Total number of carbon atoms × 100

[0118] When the aforementioned biomass content is satisfied, the carbon content derived from biomass can be increased in the adhesive, and since this does not increase carbon dioxide in the atmosphere, it is environmentally friendly. Furthermore, when an adhesive sheet that satisfies the aforementioned biomass content is applied to a display, it is preferable from the viewpoint of not incurring environmental costs.

[0119] The adhesive layer produced using the adhesive composition of the present invention may more preferably be an adhesive layer for a surface protection substrate film. The adhesive layer for the surface protection substrate film may be formed by applying the adhesive composition onto a release film coated with a silicone release agent. The adhesive layer for the surface protection substrate film can be formed using an adhesive composition for a surface protection substrate film, which is an example of the adhesive composition of the present invention. The adhesive composition for the surface protection substrate film may have the same configuration as the adhesive composition described above, so it is omitted here.

[0120] Furthermore, the present invention includes an adhesive layer for surface protection substrate films and a surface protection adhesive sheet including the surface protection substrate film.

[0121] Therefore, in order to provide the adhesive sheet for surface protection of the present invention, configurations and manufacturing methods commonly used to manufacture adhesive layers, adhesive films, or adhesive sheets in the art can be used, except for the adhesive composition for surface protection substrate films described above. For example, an adhesive layer can be manufactured by applying the adhesive composition for surface protection substrate films of the present invention to a release film coated with a silicone release agent, and furthermore, a PET film can be laminated onto the formed adhesive layer to manufacture an adhesive sheet for surface protection.

[0122] Furthermore, the present invention provides a display including the aforementioned adhesive sheet for surface protection, and the display of the present invention may include configurations commonly known in the art, as long as it includes the adhesive sheet for surface protection.

[0123] As another example, the adhesive layer produced using the adhesive composition of the present invention may more preferably be an adhesive layer for polarizing plates. The adhesive layer for polarizing plates may be formed by applying the adhesive composition to a release film coated with a silicone release agent. The adhesive layer for polarizing plates can be formed using an adhesive composition for polarizing plates, which is an example of the adhesive composition of the present invention, and the adhesive composition for polarizing plates may have the same configuration as the adhesive composition described above, so it will be omitted. Preferably, the crosslinking agent contained in the adhesive composition for polarizing plates may be present in an amount of 0.1 to 0.5 parts by weight per 100 parts by weight of acrylic copolymer, and preferably in an amount of 0.1 to 0.4 parts by weight, which can provide a more suitable adhesive strength from the viewpoint of reworkability.

[0124] Therefore, in order to provide the adhesive layer for polarizing plates of the present invention, configurations and manufacturing methods commonly used to manufacture adhesive layers, adhesive films, or adhesive sheets in the art can be used, except for the adhesive composition described above. For example, the adhesive layer may be manufactured by applying the adhesive composition for polarizing plates of the present invention to a release film coated with a silicone release agent.

[0125] Furthermore, the present invention includes an adhesive sheet for polarizing plates, which includes the adhesive layer for polarizing plates. The adhesive sheet for polarizing plates may further include a release film having a lower peeling force than the release film on which the adhesive layer for polarizing plates is formed.

[0126] In this case, the polarizing plate containing the adhesive sheet for polarizing plates can mean a polarizing plate equipped with an adhesive layer for polarizing plates. That is, a polarizing plate equipped with an adhesive layer for polarizing plates on one surface can be bonded to a glass substrate of an optical component after the release film of the adhesive layer is peeled off.

[0127] Furthermore, the present invention provides a display including the aforementioned adhesive layer for polarizing plates, and the display of the present invention may include configurations commonly known in the art, as long as it includes the adhesive layer for polarizing plates of the present invention.

[0128] The embodiments of the present invention will be described in more detail below with reference to Figure 1. However, the following drawings attached to this specification illustrate preferred embodiments of the present invention and, together with the content of the invention described above, serve to further illustrate the technical concept of the present invention. Therefore, the present invention should not be interpreted as being limited only to the matters shown in the drawings.

[0129] Figure 1 shows a display including a surface protection adhesive sheet and a polarizing plate adhesive layer according to one embodiment of the present invention.

[0130] Referring to Figure 1, the display of the present invention may have a structure in which a surface protection adhesive sheet 150, 140-1 is included on one side of the polarizing plate 100, and the surface protection adhesive sheet 150, 140-1 may have a structure in which an adhesive layer 140-1 for the surface protection substrate film is formed on one side of the surface protection substrate film 150.

[0131] The aforementioned surface protection substrate film 150 may include, but is not limited to, a polyethylene terephthalate (PET) film.

[0132] The adhesive layer 140-1 for the surface protective substrate film includes, without limitation, the contents described in the <Adhesive Composition> section above.

[0133] The polarizing plate 100 may have a structure in which protective films 130 are laminated on both sides of a polarizer 110 via adhesive 120, as shown in Figure 1. Alternatively, the protective film 130 may be formed on one side of the polarizer 110, and the other side may further include functional layers such as a phase difference adjustment layer and a refractive index adjustment layer. The phase difference adjustment layer, refractive index adjustment layer and protective film may also be laminated in sequence.

[0134] As a result, the surface protection adhesive sheets 150 and 140-1 of the present invention may have an adhesive strength of 1 N / 25 mm or less, preferably 0.01 N / 25 mm to 0.9 N / 25 mm.

[0135] On the other side of the polarizing plate 100 where the surface protective adhesive sheets 150 and 140-1 are not formed, an adhesive layer 140-2 for polarizing plates may be included so that it can be bonded to the glass substrate 160 of the liquid crystal cell or the like.

[0136] Referring to Figure 1, the display of the present invention may include an adhesive layer 140-2 for polarizing plates that adheres to one surface of the polarizing plate 100, such as to a glass substrate 160 of a liquid crystal cell. The adhesive layer 140-2 for polarizing plates may be manufactured using an adhesive composition for polarizing plates, and more specifically, it may include without limitation the contents described in the <Adhesive Composition> section above.

[0137] The adhesive composition for polarizing plates of the present invention is preferably one used to bond the glass substrate 160 of a liquid crystal cell to the polarizing plate 100, as illustrated in Figure 1. This is because, as mentioned above, it ensures excellent adhesive strength and allows for stable bonding between the polarizing plate and the glass, resulting in desirable adhesive strength from the viewpoint of reworkability when replacing the polarizing plate thereafter.

[0138] As a result, the adhesive layer formed with the polarizing plate adhesive composition of the present invention may have an adhesive strength of 1.0 N / 25 mm or more, preferably 1.0 N / 25 mm to 5 N / 25 mm.

[0139] The adhesive layer 140-1 for surface protection substrate film and the adhesive layer 140-2 for polarizing plate of the present invention may have a biomass content of 50% or more, calculated by the following formula 1 in accordance with ASTM D6866.

[0140] <Expression 1> Biomass percentage (%) = Number of carbon atoms from biomass / Total number of carbon atoms × 100

[0141] The following describes specific embodiments for carrying out the present invention, but the present invention is not limited to the following and may be appropriately modified to the extent required in the ordinary art. [Examples]

[0142] <Synthesis Example 1: Compounds of Chemical Formulas 1-3> The compounds were synthesized by decomposing and purifying canister oil to produce 2-Octanol, followed by purifying acrylic acid under acid catalyst conditions at 80°C for 3 hours with stirring. The biomass content of the synthesized compounds of chemical formulas 1-3, calculated according to ASTM D6866 and formula 1, was 73%.

[0143] <Synthesis Example 2: Compounds of Chemical Formulas 1-2> Bio-Butanol (product code W217816, manufactured by Sigma-Aldrich) and acrylic acid were synthesized by stirring and purifying under acid catalyst at 80°C for 3 hours. The biomass content of the synthesized compound of chemical formula 1-2, calculated according to formula 1 in accordance with ASTM D6866, was 57%.

[0144] <Manufacturing Example: Manufacturing of Acrylic Copolymers> Manufacturing Example 1 In a 1 L reactor equipped with a cooling device to facilitate temperature control and refluxing nitrogen gas, 100 parts by weight of a monomer mixture consisting of 70.8% by weight of n-butyl acrylate (BA), 28% by weight of methacrylate (MA), 0.2% by weight of acrylic acid (AA), and 1.0% by weight of 2-hydroxyethyl methacrylate (2-HEMA) was added. Then, 100 parts by weight of ethyl acetate (EA) was added as a solvent. After that, nitrogen gas was added for 1 hour to remove oxygen and replace the mixture, and the temperature was maintained at 62°C. After homogenizing the mixture, 0.07 parts by weight of azobisisobutyronitrile (AIBN) was added as a reaction initiator, and the reaction was carried out for 8 hours to produce an acrylic copolymer with a molecular weight of approximately 1.4 million.

[0145] Manufacturing Examples 2 to 4 The manufacturing process was carried out in the same manner as in Manufacturing Example 1, but with the composition shown in Table 1 below, to produce an acrylic copolymer.

[0146] [Table 1]

[0147] - Compounds of chemical formulas 1-2: Compounds synthesized in Synthesis Example 2, with a biomass content of 57% calculated by formula 1 in accordance with ASTM D6866. - Compounds of chemical formulas 1-3: Compounds synthesized in Synthesis Example 1, with a biomass content of 73% calculated by formula 1 in accordance with ASTM D6866. -BA: Butyl acrylate (Sigma-Aldrich) -MA: Methacrylate (Sigma-Aldrich) -2-HMEA: 2-hydroxyethyl methacrylate (Sigma-Aldrich) -AA: Acrylic acid (Sigma-Aldrich) <Examples and Comparative Examples: Manufacturing of Adhesive Compositions> Adhesive compositions for the examples and comparative examples were prepared using the compositions shown in Table 2 below. These compositions were applied to a release film coated with a silicone release agent and dried at 100°C for 2 minutes to form an adhesive layer with a thickness of 20 μm. Alternatively, a surface protective adhesive sheet was produced by laminating an 80 μm PET film treated with corona discharge onto the formed adhesive layer (Evaluations I.5, I.6), or a polarizing plate with only a corona discharge-treated triacetylcellulose (TAC) film attached was laminated onto the formed adhesive layer to produce a polarizing plate with an adhesive layer (Evaluations II.5, II.6).

[0148] [Table 2]

[0149] -AH-2100 (AEKYUNG CHEMICAL): Alicyclic isocyanate -D-110N (Mitsui Chemicals): Aromatic isocyanate -Crosslinking agent: Sodium 2-ethylhexanoate (Sigma-Aldrich) -Compound of chemical formula 2-1: HISC-03 (Korean Fine Chemical) - Antistatic agent: 1-decylpyridinium bis(fluorosulfonyl)imide

[0150] <Experimental Example I> The physical properties of the adhesive compositions produced in Examples I-1 to I-7 and Comparative Examples 1 to 4, the adhesive layers produced using these compositions, and the surface protection adhesive sheets were measured using the following methods, and the results are shown in Table 3 below.

[0151] (I.1) Evaluation of turbidity (preparation status) The adhesive compositions of Examples I-1 to I-7 and Comparative Examples 1 to 4 were visually evaluated to determine whether a whitening phenomenon occurred. <Evaluation Criteria> ○: Presence of cloudiness ×: No cloudiness

[0152] (I.2) Measurement of Biomass Content The biomass content of the adhesive layers produced using the adhesive compositions of Examples I-1 to I-7 and Comparative Examples 1 to 4 was calculated according to ASTM D6866 using the following formula 1.

[0153] [Formula 1] Biomass percentage (%) = Number of carbon atoms from biomass / Total number of carbon atoms × 100

[0154] (I.3) Evaluation of gel fraction Approximately 0.25 g of adhesive layers prepared with the adhesive compositions of Examples I-1 to I-7 and Comparative Examples 1 to 4 were attached to a 250-mesh iron mesh (100 mm x 100 mm), and the mesh was wrapped to prevent leakage of the gel. After measuring the weight (B) with a precision scale, the iron mesh was immersed in an ethyl acetate solution for 3 days. The immersed iron mesh was removed, washed in a small amount of ethyl acetate solution, dried at 120°C for 24 hours, and then measured in weight (C). The gel fraction was calculated using the measured weight with the following formula 2.

[0155] [Formula 2] Gel fraction (%) = (CA) / (BA) × 100 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 immersion and drying. Therefore, (BA) represents the initial weight of the adhesive layer, and (CA) represents the weight of the gelled adhesive layer.

[0156] (I.4) Evaluation of the curing period The adhesive compositions of Examples I-1 to I-7 and Comparative Examples 1 to 4 were cured at 23°C and 50% RH, and the gel fraction was measured daily using the same method as the gel fraction evaluation method described in (3) above. The day on which the gel fraction did not increase further, i.e., the curing period, was determined.

[0157] The curing period was determined based on the point in time when the calculated gel fraction value fell within the range of 70 to 90% and showed no change over time.

[0158] (I.5) Evaluation of the adhesive strength of surface protection adhesive sheets Surface protection adhesive sheets prepared using the adhesive compositions of Examples I-1 to I-7 and Comparative Examples 1 to 4 were cut to a length of 25 mm x width of 100 mm. After peeling off the release film, the exposed adhesive layer was attached to a glass substrate (#1737, Corning) at a pressure of 0.25 MPa. The specimens were then autoclaved for 20 minutes at a temperature of 50°C and 5 atmospheres to prepare test pieces. To measure the adhesive strength at room temperature, the prepared test pieces were left for 24 hours at a temperature of 23°C and 50% RH. Using a universal tensile testing machine (UTM, Instron), the adhesive sheets were peeled from the glass substrate at a peeling speed of 300 mm / min and a peeling angle of 180° to measure the adhesive strength at room temperature.

[0159] In this case, the adhesive strength at room temperature refers to the initial adhesive strength after adhesion, and the adhesive strength under heating is checked to confirm the phenomenon of increased adhesive strength during long-term storage or use after adhesion. The heating environment and peeling method are as follows, and were essentially confirmed through the evaluation of the peeling residue in (I.6).

[0160] To confirm the heated adhesive strength, the manufactured specimens were left for 48 hours under conditions of 50°C and 50%RH. Subsequently, the heated adhesive strength was confirmed by peeling the adhesive sheet from the glass substrate at a peeling speed of 300 mm / min and a peeling angle of 180° using a universal tensile testing machine (UTM, Instron) under conditions of 23°C and 50%RH.

[0161] (I.6) Evaluation of peeling residue After evaluating the adhesive strength of the surface protection adhesive sheet according to the method for evaluating adhesive strength described in (I.5) above, the condition of the glass substrate surface was visually inspected to confirm whether or not any residue had been generated. <Evaluation Criteria> ○: The adhesive is removed cleanly without leaving any residue, and the base film (PET film) is not torn. ×: Adhesive residue remains, or the base film (PET film) tears during the peeling process.

[0162] [Table 3]

[0163] Referring to Table 3 above, it was confirmed that the surface protection adhesive sheets produced using the adhesive compositions according to Examples I-1 to I-7 of the present invention have an excellent biomass content of 50% or more, a gel fraction of 70% or more is secured upon completion of curing, exhibit lower adhesive strength compared to polarizing plate adhesives, and allow for a reduction in curing time by adding a crosslinking aid.

[0164] More specifically, it satisfies an adhesive strength of 1 N / 25 mm or less, preferably 0.01 N / 25 mm to 0.9 N / 25 mm, exhibiting a highly desirable adhesive strength for an adhesive layer for a surface protection substrate film included in a surface protection adhesive sheet, and also does not generate any adhesive residue when the surface protection adhesive sheet is peeled off.

[0165] On the other hand, in the case of Comparative Example 1, which was manufactured with acid, the curing period was shown to be very short. However, because it does not contain the monomer represented by chemical formula 1, it not only has a biomass content of 0%, but is also corrosive to metals, and can be confirmed to be unsuitable as an adhesive composition for polarizing plates.

[0166] Furthermore, according to Comparative Examples 2 and 3, the absence of acid results in a very long curing period of 30 days, making them unsuitable as adhesives for polarizing plates compared to the adhesives of the embodiments of the present application.

[0167] Furthermore, according to Comparative Example 4, although it contains a crosslinking aid, its compatibility with aromatic isocyanates is poor, resulting in clouding and making it completely unusable as an adhesive composition for polarizing plates.

[0168] <Experimental Example II> The physical properties of the adhesive compositions produced in Examples II-1 to II-3 and Comparative Examples 1 to 4, the adhesive layers produced using these compositions, and the polarizing plates equipped with these adhesive layers were measured by the following method, and the results are shown in Table 4 below.

[0169] (II.1) Evaluation of turbidity (II.2) Measurement of Biomass Content (II.3) Evaluation of gel fraction (II.4) Evaluation of the curing period Experimental evaluations II.1 to II.4 were conducted similarly to experimental evaluations I.1 to I.4, except that the adhesive compositions of the examples were used in Examples II-1 to II-3.

[0170] (II.5) Evaluation of the adhesive strength of polarizing plates equipped with an adhesive layer Polarizing plates equipped with adhesive layers manufactured using the adhesive compositions of Examples II-1 to II-3 and Comparative Examples 1 to 4 were cut to a length of 25 mm and a width of 100 mm. After peeling off the release film, the exposed adhesive portion was attached to a glass substrate (#1737, Corning) at a pressure of 0.25 MPa, and the specimens were autoclaved for 20 minutes under conditions of 50°C and 5 atm to prepare the specimens. To measure the adhesive strength at room temperature, the prepared specimens were left for 24 hours under conditions of 23°C and 50% RH. Using a universal tensile testing machine (UTM, Instron), the polarizing plates were peeled from the glass substrate at a peeling speed of 300 mm / min and a peeling angle of 180° to measure the adhesive strength at room temperature.

[0171] In this case, the adhesive strength at room temperature refers to the initial adhesive strength after adhesion, and the adhesive strength under heating is checked to confirm the phenomenon of increased adhesive strength during long-term storage or use after adhesion. The heating environment and peeling method are as follows and were essentially confirmed through the evaluation of reworkability in (II.6).

[0172] To confirm the heated adhesion strength, the manufactured specimens were left for 48 hours under conditions of 50°C and 50%RH. Subsequently, under conditions of 23°C and 50%RH, the polarizing plates were peeled from the glass substrate at a peeling speed of 300 mm / min and a peeling angle of 180° using a universal tensile testing machine (UTM, Instron) to confirm the heated adhesion strength.

[0173] (II.6) Evaluation of reworkability After evaluating the adhesive strength of a polarizing plate equipped with an adhesive layer according to the method for evaluating adhesive strength of a polarizing plate described in (II.5) above, the condition of the glass substrate surface was visually inspected to confirm whether any adhesive residue from the polarizing plate remained. <Evaluation Criteria> ○: Removes cleanly without any residue. X: Residue remains.

[0174] (II.7) Evaluation of metal corrosion Aluminum foil was attached to adhesive layers produced using the adhesive compositions of Examples II-1 to II-3 and Comparative Examples 1 to 4, and autoclaved for 20 minutes under conditions of 50°C and 5 atmospheres. Corrosion was then observed after leaving the samples in an atmosphere of 85°C and 85% relative humidity for 15 days. <Evaluation Criteria> ○: If there is no change in the aluminum foil, ×: If discoloration occurs on the aluminum foil,

[0175] [Table 4]

[0176] Referring to Table 4 above, the adhesive layers produced using the adhesive compositions according to Examples II-1 to II-3 of the present invention have an excellent biomass content of 50% or more, and at the same time satisfy an adhesive strength of 1.0 N / 25 mm or more, preferably 1.0 N / 25 mm to 5 N / 25 mm, which is very desirable as an adhesive for polarizing plates. Furthermore, because it does not contain acid, it does not corrode metals, and despite being manufactured without acid, the curing period was shortened by more than 50% compared to the curing period of other comparative examples that did not contain acid. Moreover, despite the high adhesive strength, it has excellent reworkability, and no residue is generated on the glass substrate surface during separation.

[0177] On the other hand, in the case of Comparative Example 1, which was manufactured with acid, the curing period was shown to be very short. However, because it does not contain the monomer represented by chemical formula 1, it not only has a biomass content of 0%, but is also corrosive to metals, and can be confirmed to be unsuitable as an adhesive composition for polarizing plates.

[0178] Furthermore, according to Comparative Examples 2 and 3, the absence of acid results in a very long curing period of 30 days, making them unsuitable as adhesives for polarizing plates compared to the adhesives of the present invention.

[0179] Furthermore, according to Comparative Example 4, although it contains a crosslinking aid, its compatibility with aromatic isocyanates is poor, resulting in clouding and making it completely unusable as an adhesive composition for polarizing plates. [Explanation of Symbols]

[0180] 100: Polarizing plate 110: Polarizer 120: Adhesive 130: Protective film 140-1: Adhesive layer for surface protection substrate film 140-2: Adhesive layer for polarizing plate 150: Surface protective substrate film 160: Glass substrate of liquid crystal cell

Claims

1. An acrylic copolymer polymerized with a compound represented by the following chemical formula 1; and a crosslinking agent, The crosslinking agent is one or more compounds selected from at least one isocyanate compound selected from aliphatic isocyanate compounds and alicyclic isocyanate compounds, epoxy compounds, oxazoline compounds, aziridine compounds, and metal chelate compounds, in an adhesive composition. [Chemical formula 1] (In the above chemical formula 1, R １ is a hydrogen or methyl group, R ２ (This refers to a hydrocarbon group derived from biomass, having 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 comprises 0.1 to 0.4 parts by weight per 100 parts by weight of the acrylic copolymer.

4. The adhesive composition according to claim 2, wherein the adhesive layer formed with the adhesive composition has an adhesive strength of 1 N / 25 mm or more and 5 N / 25 mm or less.

5. The adhesive composition according to claim 1, wherein the adhesive composition is an adhesive composition for a surface protection substrate film.

6. The adhesive composition according to claim 5, wherein the crosslinking agent comprises 0.5 to 2.5 parts by weight per 100 parts by weight of the acrylic copolymer.

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

8. The adhesive composition according to claim 1, further comprising a crosslinking aid.

9. The aforementioned crosslinking aid is a sodium salt (Na ＋ ) system, calcium salt (Ca ２＋ The adhesive composition according to claim 8, wherein it is one or more compounds selected from ) and tin (Sn) compounds.

10. The adhesive composition according to claim 8, wherein the crosslinking aid comprises 0.01 to 0.1 parts by weight per 100 parts by weight of the acrylic copolymer.

11. The adhesive composition according to claim 1, wherein the compound represented by the chemical formula 1 is present in an amount of 30 to 80% by weight relative to the total weight of the monomers used in the polymerization of the acrylic copolymer.

12. The adhesive composition according to claim 1, wherein the acrylic copolymer does not contain an acidic functional group.

13. The adhesive composition according to claim 1, further comprising one or more silane coupling agents selected from the group consisting of compounds represented by the following chemical formula 2. [Chemical formula 2] (In the above chemical formula 2, R ８ This is an alkyl group having 1 to 12 carbon atoms or an alkoxy group having 1 to 12 carbon atoms. R ９ It is a divalent aliphatic hydrocarbon having 1 to 30 carbon atoms. R １０ R １２ These are, independently, hydrogen, a C1-C12 alkyl group, a C2-C12 alkenyl group, a C2-C12 alkynyl group, or a C1-C12 alkoxy group.

14. The adhesive composition according to claim 13, wherein the silane coupling agent is contained in an amount of 0.01 to 3 parts by weight per 100 parts by weight of the acrylic copolymer.

15. The adhesive composition according to claim 1, wherein the adhesive layer formed with the adhesive composition has a biomass content of 50% or more, calculated by the following formula 1 in accordance with ASTM D6866. [Formula 1] Biomass percentage (%) = Number of carbon atoms from biomass / Total number of carbon atoms × 100

16. The adhesive composition according to claim 1, further comprising one or more selected from the group consisting of an antistatic agent, a surfactant, an adhesion promoter, and an anti-aggregation agent.

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

18. An adhesive sheet comprising the adhesive layer and base film described in claim 17.

19. A display comprising the adhesive sheet described in claim 18.

Images