Adhesive composition and adhesive film containing the same

Abstract

The present invention relates to an adhesive composition and an adhesive film comprising the same, specifically to an adhesive composition comprising a first polymer resin and a second polymer resin, wherein the storage modulus value at -20°C is 109 Pa or less and the storage modulus value at 20°C is 106 Pa or less, and an adhesive film comprising the same.

Description

Technology Field

[0001] The present invention relates to an adhesive composition and an adhesive film comprising the same, specifically comprising a first polymer resin and a second polymer resin, wherein the storage modulus value at -20℃ is 10 9 The storage modulus value is 10 at Pa or less and 20℃ 6 The present invention relates to an adhesive composition having a pressure of Pa or less and an adhesive film containing the same. Background Technology

[0002] OCA (Optically Clear Adhesive) is a material applied to displays and is frequently used, for example, in mobile devices or automotive displays.

[0003] The required physical properties of OCA applied to automobiles are very different compared to OCA applied to mobile devices.

[0004] Automotive products have a much longer replacement cycle compared to mobile products. Therefore, OCA applied to automotive products is required to maintain stable physical properties for a much longer period than OCA applied to mobile products.

[0005] Furthermore, automotive products are often exposed to much higher temperatures compared to mobile products, frequently exposed to external light such as ultraviolet rays, and often subjected to conditions where high and low temperatures alternate with seasonal changes.

[0006] Therefore, OCA applied to automotive products needs to ensure long-term reliability even under much harsher conditions compared to general cases.

[0007] Specifically, high transmittance and low haze are required, along with corrosion resistance. Additionally, to facilitate the bonding process and reduce defects, lifting and bubble formation must be minimized.

[0008] Accordingly, there was a need for automotive OCA with improved plastic durability and physical properties. The problem to be solved

[0009] The technical problem to be solved by the present invention is to provide an adhesive composition having excellent durability and minimized bubble and lifting by including a first polymer resin and a second polymer resin, and an adhesive film including the same.

[0010] However, the problems that the present invention aims to solve are not limited to those mentioned above, and other unmentioned problems will be clearly understood by those skilled in the art from the description below. means of solving the problem

[0011] One embodiment of the present invention comprises a first polymer resin and a second polymer resin, wherein the storage modulus value at -20℃ is 10 9 The storage modulus value is 10 at Pa or less and 20℃ 6 A pressure-sensitive adhesive composition with a pressure of Pa or less is provided.

[0012] According to one embodiment of the present invention, the first polymer resin and the second polymer resin may be acrylate-based polymer resins.

[0013] According to one embodiment of the present invention, the first polymer resin may be an acrylate-based prepolymer.

[0014] According to one embodiment of the present invention, the second polymer resin may be included in an amount greater than 5 parts by weight and less than 25 parts by weight with respect to 100 parts by weight of the first polymer resin.

[0015] According to one embodiment of the present invention, the weight average molecular weight (Mw) of the first polymer resin may be 500,000 g / mol or more and 3,500,000 g / mol or less.

[0016] According to one embodiment of the present invention, the weight average molecular weight (Mw) of the second polymer resin may be 1,000 g / mol or more and 10,000 g / mol or less.

[0017] According to one embodiment of the present invention, the gel fraction measured after curing the adhesive composition may be 77% or more.

[0018] According to one embodiment of the present invention, the viscosity measured after curing the adhesive composition may be 2,000 cps or more and 10,000 cps or less.

[0019] One embodiment of the present invention provides an adhesive film comprising a substrate layer; and an adhesive layer; wherein the adhesive layer comprises a first polymer resin and a second polymer resin.

[0020] According to one embodiment of the present invention, the first polymer resin and the second polymer resin may be acrylate-based polymer resins.

[0021] According to one embodiment of the present invention, the first polymer resin may be an acrylate-based prepolymer.

[0022] According to one embodiment of the present invention, the second polymer resin may be included in an amount of 10 parts by weight or more and 20 parts by weight or less with respect to 100 parts by weight of the first polymer resin.

[0023] According to one embodiment of the present invention, the peel strength of the adhesive film on a substrate may be 2,000 gf / inch or more.

[0024] According to one embodiment of the present invention, the haze of the adhesive layer may be less than 1.0%.

[0025] According to one embodiment of the present invention, the color difference (b*) of the adhesive layer may be less than 0.5. Effects of the invention

[0026] An adhesive composition according to one embodiment of the present invention has a certain level of storage modulus and viscosity, and can exhibit a gel fraction greater than a certain level.

[0027] An adhesive film according to one embodiment of the present invention may have minimized bubble and lifting and excellent durability. Specific details for implementing the invention

[0028] In this specification, when a part is described as "comprising" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0029] In this specification, "A and / or B" means "A and B, or A or B".

[0030] In this specification, when a component is described as being "on" one component, this means that, unless specifically stated otherwise, other components may be placed in between, without excluding the placement of other components.

[0031] The present invention will be described in more detail below.

[0032] One embodiment of the present invention comprises a first polymer resin and a second polymer resin, wherein the storage modulus value at -20℃ is 10 9 The storage modulus value is 10 at Pa or less and 20℃ 6 It includes an adhesive composition with a Pa or less.

[0033] An adhesive composition according to one embodiment of the present invention has a certain level of storage modulus and viscosity, and can exhibit a gel fraction greater than a certain level.

[0034] According to one embodiment of the present invention, the storage modulus value at -20℃ is 2.0e +8 Pa or less, 1.9e +8 Pa or less, 1.8e +8 Pa or less, 1.7e +8 Pa or less, 1.6e +8 Pa or less, 1.5e +8 Pa or less, 1.4e +8 Pa or less or 1.3e +8It may be less than Pa.

[0035] According to one embodiment of the present invention, the storage modulus value at 20°C is 2.0e +5 Pa or less, 1.9e +5 Pa or less, 1.8e +5 Pa or less or 1.75e +5 It may be less than Pa.

[0036] According to one embodiment of the present invention, the first polymer resin and the second polymer resin may be acrylate-based polymer resins.

[0037] According to one embodiment of the present invention, the acrylate-based polymer resin may be a copolymer of acrylate-based monomer components. “(Meth)acrylic” means acrylic and / or methacrylic.

[0038] According to one embodiment of the present invention, the acrylate-based monomer is, for example, methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, neopentyl (meth)acrylate, n-hexyl (meth)acrylate, heptyl (meth)acrylate, ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, meth. Examples include dodecyl (i.e., lauryl (meth)acrylate), isotridecyl (meth)acrylate, tetradecyl (meth)acrylate, isotetradecyl (meth)acrylate, pentadecyl (meth)acrylate, cetyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, isooctadecyl (meth)acrylate, and nonadecyl (meth)acrylate.

[0039] According to one embodiment of the present invention, the acrylate-based monomer may be, for example, a (meth)acrylic acid cycloalkyl ester, a (meth)acrylic acid ester having a bicyclic aliphatic hydrocarbon group, and a (meth)acrylic acid ester having three or more aliphatic hydrocarbon groups. Examples of (meth)acrylic acid cycloalkyl esters include (meth)acrylic acid cyclopentyl, (meth)acrylic acid cyclohexyl, (meth)acrylic acid cycloheptyl, and (meth)acrylic acid cyclooctyl. Examples of (meth)acrylic acid esters having a bicyclic aliphatic hydrocarbon group include (meth)acrylic acid isobornyl.

[0040] According to one embodiment of the present invention, the acrylate-based monomer may be, for example, (meth)acrylate 2-hydroxyethyl, (meth)acrylate 2-hydroxypropyl, (meth)acrylate 2-hydroxybutyl, (meth)acrylate 3-hydroxypropyl, (meth)acrylate 4-hydroxybutyl, (meth)acrylate 6-hydroxyhexyl, (meth)acrylate 8-hydroxyoctyl, (meth)acrylate 10-hydroxydecyl, (meth)acrylate 12-hydroxylauryl, and (4-hydroxymethylcyclohexyl)methyl (meth)acrylate as a hydroxyl group-containing monomer.

[0041] According to one embodiment of the present invention, the first polymer resin may be an acrylate-based prepolymer. That is, the first polymer resin may be a partially polymerized acrylic resin.

[0042] According to one embodiment of the present invention, the acrylate-based prepolymer may be a partial polymerization of the aforementioned acrylate-based monomers. Preferably, the acrylate-based monomer may be one or more selected from the group consisting of ethylhexyl acrylate (EHA), isobornyl acrylate (IBoA), 2-hydroxyethyl acrylate (HEA), butyl acrylate (BA), cyclohexyl acrylate (CHA), 4-hydroxybutyl acrylate (HBA), and combinations thereof. By selecting the acrylate-based monomer from the above, a pressure-sensitive adhesive composition with excellent physical properties can be prepared by partial polymerization.

[0043] According to one embodiment of the present invention, the second polymer resin may be included in an amount greater than 5 parts by weight and less than 25 parts by weight with respect to 100 parts by weight of the first polymer resin. Specifically, the second polymer resin may be in an amount of 6 parts by weight or more and 24 parts by weight or less, 7 parts by weight or more and 23 parts by weight or less, 8 parts by weight or more and 22 parts by weight or less, 9 parts by weight or more and 21 parts by weight or less, or 10 parts by weight or more and 20 parts by weight or less with respect to 100 parts by weight of the first polymer resin. By controlling the weight of the second polymer resin within the above-described range, the durability of the plastic can be improved and the occurrence of bubbles and lifting can be minimized.

[0044] According to one embodiment of the present invention, the weight average molecular weight (Mw) of the first polymer resin may be 500,000 g / mol or more and 3,500,000 g / mol or less. Specifically, the weight average molecular weight (Mw) of the first polymer resin may be 600,000 g / mol or more and 3,450,000 g / mol or less, 700,000 g / mol or more and 3,400,000 g / mol or less, 800,000 g / mol or more and 3,350,000 g / mol or less, 900,000 g / mol or more and 3,300,000 g / mol or less, or 1,000,000 g / mol or more and 3,250,000 g / mol or less. By controlling the weight average molecular weight (Mw) of the first polymer resin within the above-described range, the durability of the plastic can be improved, and the occurrence of bubbles and lifting can be minimized.

[0045] According to one embodiment of the present invention, the viscosity of the first polymer resin may be 5,000 cps or more and 500,000 cps or less. Specifically, the viscosity of the first polymer resin may be 6,000 cps or more and 450,000 cps or less, 7,000 cps or more and 400,000 cps or less, 8,000 cps or more and 350,000 cps or less, 9,000 cps or more and 330,000 cps or less, or 10,000 cps or more and 300,000 cps or less. By controlling the viscosity of the first polymer resin within the above-described range, the durability of the plastic can be improved, and the occurrence of bubbles and lifting can be minimized.

[0046] According to one embodiment of the present invention, the weight average molecular weight (Mw) of the second polymer resin may be 1,000 g / mol or more and 10,000 g / mol or less. Specifically, the weight average molecular weight (Mw) of the second polymer resin may be 2,000 g / mol or more and 9,000 g / mol or less, 3,000 g / mol or more and 8,000 g / mol or less, 4,000 g / mol or more and 7,000 g / mol or less, 4,500 g / mol or more and 6,000 g / mol or less, or 4,500 g / mol or more and 5,500 g / mol or less. By controlling the weight average molecular weight (Mw) of the second polymer resin within the above-described range, the durability of the plastic can be improved and the occurrence of bubbles and delamination can be minimized.

[0047] According to one embodiment of the present invention, a multifunctional crosslinking agent may be further included. By further including the multifunctional crosslinking agent, the acrylate-based polymer resin can be crosslinked to control the gel fraction. Examples of the multifunctional crosslinking agent include a multifunctional (meth)acrylate. For example, ester compounds of (meth)acrylic acid and polyhydric alcohols such as (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,2-ethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,12-dodecanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate; allyl (meth)acrylate; vinyl (meth)acrylate; divinylbenzene; epoxyacrylate; Examples include polyester acrylate; urethane acrylate; butyl di(meth)acrylate; and hexyl di(meth)acrylate.

[0048] According to one embodiment of the present invention, the polyfunctional crosslinking agent may be included in an amount of 0.05 parts by weight or more and 0.5 parts by weight or less per 100 parts by weight of the first polymer resin, preferably in an amount of 0.1 parts by weight or more and 0.3 parts by weight or less, and more preferably in an amount of 0.2 parts by weight.

[0049] According to one embodiment of the present invention, a photoinitiator may be further included. Any photoinitiator capable of initiating a polymerization reaction of the adhesive composition through light irradiation, etc. may be used. For example, alpha-hydroxyketone compounds (e.g., IRGACURE 184, IRGACURE 500, IRGACURE 2959, DAROCUR 1173; Ciba Specialty Chemicals); phenylglyoxylate compounds (e.g., IRGACURE 754, DAROCUR MBF; Ciba Specialty Chemicals); benzyldimethylketal compounds (e.g., IRGACURE 651; Ciba Specialty Chemicals); α-aminoketone compounds (e.g., IRGACURE 369, IRGACURE 907, IRGACURE 1300; Ciba Specialty Chemicals); Monoacylphosphine compounds (MAPO) (e.g., DAROCUR TPO; Ciba Specialty Chemicals); Bisacylphosphene compounds (BAPO) (e.g., IRGACURE 819, IRGACURE 819DW; Ciba Specialty Chemicals); Phosphine oxide compounds (e.g., IRGACURE 2100; Ciba Specialty Chemicals); Metallocene compounds (e.g., IRGACURE 784; Ciba Specialty Chemicals); Iodonium salts (e.g., IRGACURE 250; Ciba Specialty Chemicals); Examples include mixtures of one or more of the above (e.g., DAROCUR 4265, IRGACURE 2022, IRGACURE 1300, IRGACURE 2005, IRGACURE 2010, IRGACURE 2020; Ciba Specialty Chemicals), etc., and one or more of the above may be used, but are not limited thereto.

[0050] According to one embodiment of the present invention, the photoinitiator may be included in an amount of 0.1 parts by weight or more and 0.5 parts by weight or less per 100 parts by weight of the first polymer resin. Preferably, it may be 0.2 parts by weight or more and 0.4 parts by weight or less, and more preferably 0.3 parts by weight.

[0051] According to one embodiment of the present invention, a coupling agent may be further included. The coupling agent improves the adhesion and adhesive stability of the adhesive, thereby improving heat resistance and moisture resistance, and also improves adhesive reliability even when left for a long period under harsh conditions. The above coupling agents include, for example, gamma-glycidoxypropyl triethoxysilane, gamma-glycidoxypropyl trimethoxysilane, gamma-glycidoxypropyl methyldiethoxysilane, gamma-glycidoxypropyl triethoxysilane, 3-mercaptopropyl trimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, gamma-methacryloxypropyl trimethoxysilane, gamma-methacryloxypropyl triethoxysilane, gamma-aminopropyl trimethoxysilane, gamma-aminopropyl triethoxysilane, 3-isocyanatopropyl triethoxysilane, gamma-acetoacetatepropyl trimethoxysilane, gamma-acetoacetatepropyl triethoxysilane, beta-cyanoacetyl trimethoxysilane, beta-cyanoacetyl triethoxysilane, acetoxyacetyl Trimethoxysilanes, etc., may be used, and one or more of the above may be used. It is preferable to use a silane-based coupling agent having an acetoacetate group or a beta-cyanoacetyl group, but is not limited thereto.

[0052] According to one embodiment of the present invention, the coupling agent may be 0.05 parts by weight or more and 0.5 parts by weight or less per 100 parts by weight of the first polymer resin, preferably 0.1 parts by weight or more and 0.3 parts by weight or less, and more preferably 0.2 parts by weight.

[0053] According to one embodiment of the present invention, a rust inhibitor may be further included. The rust inhibitor is not particularly limited, but examples include amine compounds, benzotriazole compounds, nitrites, etc. In addition, examples include ammonium benzoate, ammonium phthalate, ammonium stearate, ammonium palmitate, ammonium oleate, ammonium carbonate, dicyclohexylamine benzoate, urea, urotropin, thiourea, phenyl carbamate, cyclohexylammonium-N-cyclohexylcarbamate (CHC), etc. Furthermore, the rust inhibitor may be used alone or in combination of two or more types. Preferably, it may be a benzotriazole compound. In particular, it is preferable that the rust inhibitor be a benzotriazole compound in that it can obtain high levels of adhesive reliability, transparency, and corrosion resistance properties with a good balance.

[0054] According to one embodiment of the present invention, the rust inhibitor may be included in an amount of 0.1 parts by weight or more and 0.5 parts by weight or less per 100 parts by weight of the first polymer resin. Preferably, it may be 0.2 parts by weight or more and 0.4 parts by weight or less, and more preferably 0.3 parts by weight.

[0055] According to one embodiment of the present invention, the gel fraction measured after curing the adhesive composition may be 77% or more. Specifically, the gel fraction measured after curing the adhesive composition may be 77% or more and 95% or less, 77% or more and 94% or less, 77% or more and 92% or less, 77% or more and 90% or less, 77% or more and 88% or less, 77% or more and 86% or less, 77% or more and 84% or less, or 77% or more and 85% or less. By controlling the gel fraction measured after curing the adhesive composition within the above-described range, plastic durability can be improved and the occurrence of bubbles and delamination can be minimized.

[0056] According to one embodiment of the present invention, the viscosity measured after curing the adhesive composition may be 2,000 cps or more and 10,000 cps or less. Specifically, the viscosity measured after curing the adhesive composition may be 3,000 cps or more and 9,500 cps or less, 4,000 cps or more and 9,000 cps or less, 5,000 cps or more and 8,500 cps or less, 6,000 cps or more and 8,500 cps or less, 7,000 cps or more and 8,500 cps or less, 7,500 cps or more and 8,400 cps or less, 7,600 cps or more and 8,300 cps or less, 7,700 cps or more and 8,200 cps or less, or 7,900 cps or more and 8,100 cps or less. By controlling the viscosity measured after curing the adhesive composition within the above-mentioned range, the durability of the plastic can be improved and the occurrence of bubbles and lifting can be minimized.

[0057] One embodiment of the present invention comprises a substrate layer; and an adhesive layer; wherein the adhesive layer comprises an adhesive film comprising a first polymer resin and a second polymer resin.

[0058] According to one embodiment of the present invention, the substrate layer may be a resin film. Specifically, it may include plastic materials such as polyester series, polycarbonate series, polyolefin series, polyimide series, etc., such as polyethylene terephthalate (PET).

[0059] According to one embodiment of the present invention, the first polymer resin and the second polymer resin may be acrylate-based polymer resins.

[0060] According to one embodiment of the present invention, the first polymer resin may be an acrylate-based prepolymer.

[0061] According to one embodiment of the present invention, the second polymer resin may be included in an amount of 10 parts by weight or more and 20 parts by weight or less with respect to 100 parts by weight of the first polymer resin.

[0062] The details regarding the first polymer resin and the second polymer resin above are as described above.

[0063] According to one embodiment of the present invention, the peel force of the adhesive film on the substrate may be 2,000 gf / inch or more. Specifically, the peel force of the adhesive film on the substrate may be 2,000 gf / inch or more and 4,500 gf / inch or less, 2,500 gf / inch or more and 4,400 gf / inch or less, or 2,600 gf / inch or more and 4,300 gf / inch or less. Durability can be improved by adjusting the peel force of the adhesive film on the substrate within the above-described range.

[0064] According to one embodiment of the present invention, the haze of the adhesive layer may be less than 1.0%. Specifically, the haze of the adhesive layer may be 0.3% or more and 0.9% or less, 0.4% or more and 0.8% or less, 0.42% or more and 0.7% or less, 0.44% or more and 0.65% or less, 0.46% or more and 0.6% or less, or 0.47% or more and 0.59% or less. Optical properties can be improved by controlling the haze of the adhesive layer within the above-described range.

[0065] According to one embodiment of the present invention, the color difference (b*) of the adhesive layer may be less than 0.5. Specifically, the color difference (b*) of the adhesive layer may be 0.15 or more and 0.45 or less, 0.16 or more and 0.43 or less, 0.17 or more and 0.41 or less, 0.18 or more and 0.39 or less, 0.19 or more and 0.37 or less, or 0.20 or more and 0.36 or less. Optical properties can be improved by adjusting the color difference (b*) of the adhesive layer within the above-described range.

[0066] Hereinafter, the present invention will be described in detail with reference to examples to specifically explain the invention. However, the embodiments according to the present invention may be modified in various different forms, and the scope of the present invention is not to be interpreted as being limited to the embodiments described below. The embodiments of this specification are provided to more completely explain the present invention to those with average knowledge in the art.

[0068] <Preparation Example: Preparation of partially polymerized acrylic resin (first polymer resin A)>

[0069] 60 parts by weight of ethylhexyl acrylate (EHA); 20 parts by weight of isobornyl acrylate (IBoA); and 20 parts by weight of 2-hydroxyethyl acrylate (HEA) were introduced into a 3L reactor equipped with a cooling device for easy temperature control and nitrogen gas reflux, and partial polymerization was performed to obtain a syrup with a viscosity of 300,000 cps. The weight-average molecular weight of the partially polymerized acrylic resin (A) was 3.23 million g / mol.

[0071] <Preparation Example: Preparation of partially polymerized acrylic resin (first polymer resin B)>

[0072] 68 parts by weight of ethylhexyl acrylate (EHA); 14.5 parts by weight of N-pyrrolidone (NVP); and 17.5 parts by weight of 2-hydroxyethyl acrylate (HEA) were introduced into a 3L reactor equipped with a cooling device for easy temperature control and nitrogen gas reflux, and by partial polymerization, a syrup with a viscosity of 12,000 cps was obtained. The weight-average molecular weight of the partially polymerized acrylic resin (B) was 1.2 million g / mol.

[0074] <Preparation Example: Preparation of partially polymerized acrylic resin (first polymer resin C)>

[0075] In a 3L reactor equipped with a cooling device for easy temperature control and nitrogen gas reflux, 66 parts by weight of butyl acrylate (BA); 10 parts by weight of cyclohexyl acrylate (CHA); 12 parts by weight of 4-hydroxybutyl acrylate (HBA); and 12 parts by weight of 2-hydroxyethyl acrylate (HEA) were introduced and partially polymerized to obtain a syrup with a viscosity of 10,000 cps. The weight-average molecular weight of the partially polymerized acrylic resin (C) was 1 million g / mol.

[0077] <Synthesized Example: Second Polymer Resin>

[0078] 100 parts by weight of ethyl acetate (EAc), 60 parts by weight of dicyclofentanyl methacrylate (DCPMA), 40 parts by weight of methyl methacrylate (MMA), and 7 parts by weight of molecular weight regulator dodecyl mercaptan are added to a polymerization reactor. Then, stirring is carried out at 70°C for 40 minutes while introducing nitrogen. After 40 minutes, the internal temperature of the polymerization reactor is set to be maintained at 70°C, and 0.2 parts of V-65 (2,2'-Azobis(2,4-dimethylvaleronitrile)) is added as a thermal polymerization initiator to proceed with polymerization. 0.2 parts by weight of the thermal polymerization initiator is added 2 hours after the addition of the first initiator. The reaction is terminated 5 hours after the addition of the second initiator. The completed polymerization resin is placed in a 120°C oven to volatilize residual monomers and additives, thereby obtaining a second solid polymer resin with a molecular weight (Mw) of 5,000 g / mol.

[0080] <Example 1>

[0081] To 100 parts by weight of the partially polymerized acrylic resin (A) prepared in Preparation Example 1 above, 0.2 parts by weight of a polyfunctional crosslinking agent, hexanediol diacrylate, 0.2 parts by weight of a coupling agent (KBM 403, manufactured by Shin-Etsu), 0.3 parts by weight of a photoinitiator (Irgacure 651, manufactured by Ciba Specialty Chemicals), and 0.3 parts by weight of a rust inhibitor (benzotriazole, Daemyung Chemical) were added to prepare an adhesive composition, and a coating solution having a viscosity of 8,000 cps was prepared therefrom. Subsequently, the prepared coating solution was coated onto a release-treated polyethylene terephthalate film (XD500P, Toray Advanced Materials, thickness: 75 μm) using a bar coater so that the thickness after UV curing was 125 μm. Afterwards, an adhesive film was prepared by curing it by irradiating it with ultraviolet light for 5 minutes using a UV lamp.

[0083] <Examples 2 to 4 and Comparative Examples 1 to 3>

[0084] An adhesive film was prepared in the same manner as in Example 1, except that the composition of the adhesive composition was changed as shown in Table 1 below.

[0086] First polymer resin Second polymer resin Polyfunctional crosslinking agent Photoinitiator coupling agent Rust inhibitor Example 1 A 10 0.2 0.3 0.2 0.3 Example 2 A 20 0.2 0.3 0.2 0.3 Example 3 B 20 0.2 0.3 0.2 0.3 Example 4 C 20 0.2 0.3 0.2 0.3 Comparative Example 1 A 0 0.2 0.3 0.2 0.3 Comparative Example 2 A 5 0.2 0.3 0.2 0.3 Comparative Example 3 A 25 0.2 0.3 0.2 0.3

[0087] Content Unit: parts by weight

[0088] Polyfunctional crosslinking agent: Hexanediol diacrylate (HDDA)

[0089] Coupling agent: KBM 403, Shin-Etsu (made)

[0090] Photoinitiator: Irgacure 651, manufactured by Ciba Specialty Chemicals

[0091] Rust inhibitor: Benzotriazole, manufactured by Daemyung Chemical

[0093] <Experimental Example>

[0094] The physical properties of the adhesive compositions and adhesive films prepared in the above examples and comparative examples were measured using the method presented below.

[0095] 1. Plastic outgassing durability

[0096] The adhesive film prepared in the above examples and comparative examples was cut to a size of 3 cm x 3 cm, attached to a plastic sheet on one side, and placed on glass (0.2 T) on the other side, then laminated by autoclaving (4 bar, 40°C, 20 min). Afterward, bubbles and lifting were checked after 100 hours under constant temperature and humidity conditions (85°C / 85%).

[0098] 2. Measurement of substrate peel strength

[0099] The adhesive film prepared in the above examples and comparative examples was cut to a size of 25 mm × 20 cm (width × height), and after peeling off the release film, it was attached to stainless steel (SUS 304) by reciprocating a 2 kg roller 5 times. After 20 minutes had elapsed, the peel strength was measured using a tensile testing machine under conditions of a peel speed of 300 mm / min and a peel angle of 180°.

[0101] 3. Gel fraction

[0102] The cured product (adhesive) of the adhesive composition was cut to a size of 5 cm × 5 cm, placed in a polyethylene bottle, and its weight (a) was measured. Subsequently, ethyl acetate was added to the polyethylene bottle to ensure the adhesive was sufficiently submerged, and the mixture was left at room temperature for 24 hours. Then, the adhesive and ethyl acetate from the polyethylene bottle were poured into a wire mesh (weight: b) cut to a size of 14 cm × 14 cm and filtered. Afterward, the wire mesh filtered with the adhesive was dried in an oven at 110 ℃ for 2 hours, and its weight (c) was measured. Subsequently, the gel fraction (unit: %) was measured by substituting each of the measured weights a, b, and c into the following general formula 1.

[0103] <General Formula 1>

[0104] Gel fraction = ((cb) / a) × 100

[0106] 4. Evaluation of cloudiness

[0107] Evaluation of anti-cloudiness performance: The above adhesive film was attached to a glass substrate with a thickness of 1.1 T using a 2 kg roller, and a glass substrate with a thickness of 0.55 T was laminated on top of it. Then, after being placed in an autoclave at 40 ℃ and 4 bar for 20 minutes, the specimen was placed in an oven at a temperature of 85 ℃ and a relative humidity of 85 RH%, and the occurrence of cloudiness was visually checked after 3 days (after 100 hours). The anti-cloudiness performance was evaluated as ○ if no cloudiness occurred and X if cloudiness occurred.

[0109] 5. Method for Measuring Storage Modulus

[0110] An adhesive layer with a thickness of about 1 mm was prepared using the adhesive composition prepared in the above example or comparative example. Then, the adhesive between the release films was cut to form a cylindrical specimen of 8 mm × 1 mm (= diameter × thickness), and the storage modulus at -20°C and 20°C was measured using a kinetic rheological property measuring instrument (ARES, RDA, TA Instruments Inc.) while applying shear stress between parallel plates at a frequency of 1 Hz.

[0112] 6. Measurement of Optical Properties

[0113] Transmittance / Haze:

[0114] After attaching the manufactured adhesive layer to a 1.1 T glass surface in the form of glass / adhesive layer / glass, transmittance / haze was measured using an NDH 5000 (Nippon Denshoku).

[0115] Optical / b* measurement:

[0116] After attaching the manufactured adhesive layer to a 1.1T glass surface in the form of glass / adhesive layer / glass, the color difference was measured using CM-3600A (Konica Minolta).

[0118] 7. Printed height difference

[0119] The manufactured adhesive layer was laminated onto a printed step (black, 70 µm) and laminated by autoclaving (4 bar, 40°C, 20 min). Afterward, bubbles and lifting were checked after 100 hours under constant temperature and humidity conditions (85°C / 85%).

[0121] G'(-20℃) G'(20℃) Substrate peel strength gf / inch Color difference (b*) Haze(%) Gel(%) PC plastic durability Print step difference (~70㎛) Whiteness evaluation Example 1 1.16e +8 1.57e +5 4000 0.22 0.47 82 ○ ○ ○ Example 2 1.30e +8 1.68e +5 4300 0.20 0.49 77 ○ ○ ○ Example 3 9.40e +7 1.73e +5 3000 0.36 0.55 78 ○ ○ ○ Example 4 1.10e +8 1.53e +5 2900 0.32 0.59 80 ○ △ ○ Comparative Example 1 8.25e +7 1.44e +5 3500 0.23 0.45 82 X ○ X Comparative Example 2 9.75e +7 1.54e +5 3850 0.22 0.46 80 X ○ X Comparative Example 3 1.65e +8 1.71e +5 4620 0.25 0.50 74 X X X

[0122] As shown in Table 2 above, the adhesive films prepared in Examples 1 to 4 according to the present invention satisfy a gel fraction of 77% or more, and it can be confirmed that the plastic durability is good without bubbles or lifting. In addition, it can be confirmed that there are no problems in using them as optical adhesive films because the haze and optical properties are excellent.

[0123] On the other hand, as seen in Comparative Examples 1 and 2, when the second polymer resin is in an amount less than the appropriate amount, it can be confirmed that the plastic durability properties are not suitable, and when there is an excess amount, as seen in Comparative Example 3, it can be confirmed that although the durability is satisfactory, the printing step is not suitable.

[0124] Accordingly, the adhesive composition according to one embodiment of the present invention and the adhesive film containing the same include a first polymer resin and a second polymer resin, thereby minimizing the occurrence of bubbles and lifting and providing excellent durability.

Claims

Claim 1 A prepolymer comprising a first polymer resin and a second polymer resin, wherein the second polymer resin is included in an amount of 10 to 20 parts by weight per 100 parts by weight of the first polymer resin, and the first polymer resin is a prepolymer partially polymerized from monomers comprising 60 to 68 parts by weight of ethylhexyl acrylate (EHA) or butyl acrylate (BA) per 100 parts by weight of the first polymer resin and one or more selected from the group consisting of isobornyl acrylate (IBoA), 2-hydroxyethyl acrylate (HEA), cyclohexyl acrylate (CHA), and combinations thereof; wherein the weight average molecular weight (Mw) of the second polymer resin is 2,000 g / mol or more and 9,000 g / mol or less, and the storage modulus value at -20℃ is 9.4×10⁻⁶ 7 Pa or more than 1.30×10 8 The storage modulus value at Pa or less and 20℃ is 1.53×10 5 Pa or more than 1.73×10 5 Adhesive composition having Pa or less. Claim 2 An adhesive composition according to claim 1, wherein the second polymer resin is an acrylate-based polymer resin. Claim 3 delete Claim 4 delete Claim 5 An adhesive composition according to claim 1, wherein the weight average molecular weight (Mw) of the first polymer resin is 500,000 g / mol or more and 3,500,000 g / mol or less. Claim 6 delete Claim 7 delete Claim 8 An adhesive composition according to claim 1, wherein the viscosity measured after curing the adhesive composition is 2,000 cps or more and 10,000 cps or less. Claim 9 An adhesive film comprising a substrate layer; and an adhesive layer; wherein the adhesive layer is made of an adhesive composition according to claim 1. Claim 10 delete Claim 11 delete Claim 12 delete Claim 13 An adhesive film according to claim 9, wherein the peel strength of the adhesive film against a substrate is 2,000 gf / inch or more. Claim 14 An adhesive film according to claim 9, wherein the haze of the adhesive layer is less than 1.0%. Claim 15 An adhesive film according to claim 9, wherein the color difference (b*) of the adhesive layer is less than 0.5.

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