TWI886809B - Adhesive film for surface protection, adhesive sheet and optical member - Google Patents

Abstract

An adhesive film, an optical sheet, and an optical member are disclosed. The adhesive film for surface protection comprises a cured product of a composition for adhesive films, which comprises a curable component comprising a urethane-based binder, a curing agent and a plasticizer, and has a creep indentation (CI) value of less than 5%.

Description

Adhesive films, adhesive sheets and optical components for surface protection

[ Cross-references to related applications ]

This application claims priority to and the benefits of Korean Patent Application No. 10-2023-0046277 filed on April 7, 2023 in the Korean Intellectual Property Office, the entire disclosure of which is incorporated herein by reference.

The present invention relates to an adhesive film, an adhesive sheet and an optical component for surface protection.

The film for surface protection is adhered to the exposed surface of an electronic component or an optical component (e.g., a liquid crystal display (LCD), an organic EL display, a touch panel using the same, a camera lens unit, an electronic device, etc.) to prevent defects from being generated during processing, assembly, inspection, transportation, etc. When surface protection is no longer required, the film for surface protection is removed from the optical component or the electronic component. From the process of manufacturing the optical component or the electronic component to the final transportation through the assembly process, the inspection process, the transportation process, etc., the same film for surface protection is increasingly used.

As a film for surface protection, an acrylic surface protection film using an acrylic resin in an adhesive layer is known in the art. However, since the acrylic surface protection film has low wettability, bubbles may be trapped between the adherend and the surface protection film. In addition, since the acrylic surface protection film may generate adhesive residues after peeling, the acrylic surface protection film is not suitable as a surface protection film for protecting the surface of a component (such as an optical component or an electronic component), which may be easily affected by foreign matter.

In recent years, films for surface protection using urethane adhesive resins in the adhesive layer have been reported in the art.

Korean Patent Publication No. 2012-0050136 and the like disclose the background art of the present invention.

An object of the present invention is to provide an adhesive film for surface protection which protects an adherend and can be removed from the adherend without deforming and/or damaging the adherend after being bonded to the adherend.

Another object of the present invention is to provide an adhesive film for surface protection which, after being bonded to an adherend, does not generate bubbles at its edge due to delamination of the adhesive film during laser cutting.

Another object of the present invention is to provide an adhesive film for surface protection having good dent resistance.

Another object of the present invention is to provide an adhesive film for surface protection which has a good appearance even after being left for a long time under high temperature and high humidity conditions.

Another object of the present invention is to provide an adhesive film for surface protection having good wetting properties and peeling strength against an adherend over time.

One aspect of the present invention relates to an adhesive film for surface protection.

The adhesive film for surface protection comprises a cured product of a composition for an adhesive film, the composition comprising a curable component including a urethane adhesive, a curing agent and a plasticizer, and the adhesive film has a creep indentation (CI) value of less than 5%.

The adhesive sheet according to the present invention comprises the adhesive film for surface protection according to the present invention.

The optical component according to the present invention comprises an optical film and an adhesive film for surface protection according to the present invention formed on at least one surface of the optical film.

The present invention provides an adhesive film for surface protection, which protects an adherend and can be removed from the adherend without deforming and/or damaging the adherend after being adhered to the adherend.

The present invention provides an adhesive film for surface protection, which does not generate bubbles at its edge due to delamination of the adhesive film during laser cutting after being bonded to an adherend.

The present invention provides an adhesive film for surface protection having good dent resistance.

The present invention provides an adhesive film for surface protection which has a good appearance even after being left for a long time under high temperature/humidity conditions.

The present invention provides an adhesive film for surface protection, which has good wetting properties and peeling strength against an adherend over time.

Hereinafter, embodiments of the present invention will be described in detail. However, it should be understood that the present invention is not limited to the following embodiments and may be implemented in different ways. The following embodiments are provided to provide a thorough understanding of the present invention to those skilled in the art.

The terms used herein are for the purpose of describing exemplary embodiments and are not intended to limit the scope of the present invention.Herein, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include the plural forms as well.

Herein, “adherend” may include a glass plate, a plastic film, or a panel of a display device, but is not limited thereto.

Herein, "peel strength" is a value measured when an adhesive film is separated from an alkali-free glass plate provided as an adherend under the conditions of a peeling rate of 2,400 mm/min and a peeling angle of 180° at 23°C and 50% relative humidity (RH) in accordance with JIS Z0237.

Herein, the "CI value" is a value measured by the method shown in FIG2. Referring to FIG2, a sample is prepared by sequentially stacking a black acrylic substrate 1, an adhesive film 2 for surface protection, and a base film 3. Then, with the ball head 4 of the nanoindenter placed at the center of the base film 3 of the sample (wherein the portion of the ball head contacting the base film has a spherical shape with a diameter of 0.4 millimeters (mm)), the sample is gradually pressed with the ball head for 20 seconds (sec) until the pressing load of the ball head reaches 600 millinewtons (mN), and maintained at this load for 5 seconds, and then the force is released to obtain the CI value by automatic calculation using the nanoindenter.

The nanoindenter may be a Fischerscope HM2000LT (HELMUT-FISCHER), but is not limited thereto. The substrate film may have a thickness of 38 μm to 100 μm, and may be a polymer film, such as a polyester film, preferably a polyethylene terephthalate film. The sample may have a size of 100 mm×50 mm (length×width, rectangular form). The black acrylic substrate may be an acrylic substrate having a thickness of 1,000 μm to 2,000 μm, such as CL-885 (NITTO JUSHI KOGY). The CI value may be measured at 23°C and 50% relative humidity (RH).

Herein, "(meth)acryl" refers to acryl and/or methacryl.

When used herein to express a specific numerical range, “X to Y” means values greater than X and less than Y (X≤ and ≤Y).

The adhesive film for surface protection is a processing film that is bonded to an adherend for temporary protection of the adherend and is removed from the adherend when protection is no longer required. The adhesive film for surface protection is required to protect the adherend when bonded to the adherend and to be removed from the adherend without deforming and/or damaging the adherend. For this purpose, the adhesive film is required to have a predetermined level of peeling strength, but is not limited thereto.

In one embodiment, the adhesive film for surface protection may have a peel strength of 2 gf/inch or less. Within this range, the adhesive film has a low peel strength to be easily peeled from an adherend without deforming and/or damaging the adherend after being bonded to the adherend.

Specifically, the adhesive film may have a peel strength of 0.8 gf/inch to 2 gf/inch, more specifically 1 gf/inch to 1.8 gf/inch. Within this range, the adhesive film may protect the adherend, may be removed from the adherend without deforming and/or damaging the adherend, and may exhibit good reliability by preventing bubbles from being generated at the edge thereof due to delamination when laser cutting a laminate of the adherend and the adhesive film.

When left for a long time under high temperature and high humidity conditions, conventional adhesive films for surface protection may be contaminated or exhibit a poor appearance due to elution of components (e.g., plasticizers) from the adhesive film. Such contamination and appearance defects may cause an increase in variation in the peel strength of the adhesive film when the adhesive film is left for a long time under high temperature and high humidity conditions, thereby making it difficult for the adhesive film to protect the adherend. In addition, after being bonded to the adherend, the adhesive film for surface protection undergoes an assembly process, an inspection process, and a transportation process of a typical optical display. In so many processes, the laminate of the adhesive film and the adherend may be cut into a predetermined size. At this time, contamination and cosmetic defects cause defects in the cutting process.

The adhesive film for surface protection according to the present invention does not suffer from elution of components (specifically, plasticizer) derived from the adhesive film, thereby preventing surface contamination of the adhesive film, while ensuring good appearance even after standing for a long time under high temperature and high humidity conditions. Therefore, the adhesive film for surface protection according to the present invention can provide the effect of protecting the adherend even after standing for a long time under high temperature/humidity conditions without causing defects during the cutting process.

The adhesive film for surface protection according to the present invention has a CI value of less than 5%. At a CI value of 5% or more, the adhesive film for surface protection has low resistance to pits generated during maintenance and transportation after the adhesive film is attached to the adherend, thereby causing damage to the adherend. Specifically, the adhesive film may have a CI value of 1% or more to less than 5%, more specifically 2% to 4.8%.

The adhesive film for surface protection according to the present invention may have good peel strength over time. Specifically, the adhesive film may have a peel strength variation rate of -50% to 20%, as calculated according to Equation 1. Within this range, the adhesive film can provide an effect of protecting the adherend even when it is bonded to the adherend again after being left for a long time under high temperature and high humidity conditions, and can be removed from the adherend without deforming and/or damaging the adherend. Specifically, the adhesive film may have a peel strength variation rate of -30% to 20%, as calculated according to Equation 1: Peel strength variation rate = [(P2 - P1)/P1] × 100,      --- (1) Wherein P1 indicates the initial peel strength of the adhesive film with respect to the alkali-free glass plate (unit: gf/inch), and P2 indicates the peel strength of the adhesive film with respect to the alkali-free glass plate after the adhesive film is left at 85°C and 85% RH for 10 days (unit: gf/inch).

In one embodiment, in Equation 1, P1 of the adhesive film may be 2 gf/inch or less, 0.8 gf/inch to 2 gf/inch, and more specifically 1 gf/inch to 1.8 gf/inch.

In one embodiment, in Equation 1, P2 of the adhesive film may be 0.8 gf/inch to 2 gf/inch, more specifically 1 gf/inch to 1.8 gf/inch.

At 25°C, the adhesive film may have a modulus of 0.05 MPa to 0.8 MPa. Within this range, the adhesive film may have good wettability to an adherend (e.g., a panel) to bond to the adherend without generating bubbles and/or delamination, and may have good anti-scattering properties to ensure good cuttability and processability. Specifically, the adhesive film may have a modulus of 0.1 MPa to 0.8 MPa, more specifically 0.5 MPa to 0.8 MPa at 25°C. Here, "modulus" refers to storage modulus, and may be measured by typical methods known to those skilled in the art.

In the visible spectrum, for example, at a wavelength of 550 nanometers (nm), the adhesive film may have a haze of 5% or less, specifically 0% to 3%. Within this range, the adhesive film may exhibit good cuttability and processability when cut after being bonded to an adherend.

The adhesive film may have a thickness of 100 microns or less, for example, greater than 0 microns to 75 microns. Within this range, the adhesive film may protect the adherend when attached to the adherend and may be easily removed from the adherend.

The adhesive film may include a cured product of the composition for an adhesive film. Next, the composition for an adhesive film according to an embodiment of the present invention will be described.

The composition for the adhesive film comprises: a curable component including a urethane adhesive; a curing agent; and a plasticizer, wherein the plasticizer comprises the plasticizer described below.

Curable component

The curable component is cured by the curing agent to form a matrix of the adhesive film.

The curable component includes a urethane binder.

The urethane adhesive may include at least one urethane bond and at least one hydroxyl group (-OH). Since the urethane adhesive includes at least one hydroxyl group, the urethane adhesive may be cured by a curing agent to form a matrix of an adhesive film while providing peel strength.

In the curable component, the urethane binder may be present in an amount of 60 weight percent (wt%) to 100 wt%, specifically 95 wt% to 100 wt%, more specifically 100 wt%. Within this range, the urethane binder can impart peel strength to the adhesive film.

The urethane adhesive may have a weight average molecular weight (Mw) of greater than 60,000 g/mol to less than 150,000 g/mol. Within this range, the adhesive film does not suffer from elution of the plasticizer even after standing for a long time under high temperature and high humidity conditions, and may exhibit good pitting resistance. Preferably, the urethane adhesive has a weight average molecular weight of 80,000 g/mol to 100,000 g/mol. Here, the "weight average molecular weight" may be measured by gel permeation chromatography based on a polystyrene standard.

In one embodiment, the urethane adhesive may be a non-(meth)acrylic urethane adhesive that does not contain a (meth)acrylic group. With this component, the adhesive film can easily achieve the effect of the present invention.

The urethane adhesive can be prepared by reacting at least one type of polyol with at least one type of polyisocyanate compound. The urethane adhesive can be a random copolymer having units derived from the polyol.

The polyol may include at least one selected from polyether polyol, polyester polyol, polyacrylic polyol, polycaprolactone polyol and polycarbonate polyol. The polyol may include at least one polyether polyol and may further include at least one polyester polyol.

The urethane adhesive may contain units derived from polyether polyols. The urethane adhesive may further contain units derived from polyester polyols. In this case, the effects of the present invention can be easily achieved.

The polyether polyol may be a polyether polyol having an alkylene oxide group and two or more hydroxyl groups, such as a trifunctional polyether polyol (polyether triol) or a difunctional polyether polyol (polyether diol) (such as polyethylene glycol, polypropylene glycol and polytetramethylene glycol), a trifunctional polyether polyol (polyether triol) of a glycerol alkylene oxide adduct, etc. Therefore, the urethane binder becomes a hyperbranched binder and thus may have a textured structure rather than a linear shape, thereby making it easier to achieve the effect of the present invention. A hyperbranched binder refers to a polymer having many terminal functional groups and a branched dendritic structure.

When preparing a urethane adhesive, a polyether polyol may be used alone or in combination.

The polyether polyol may have a number average molecular weight of 400 to 10,000, more specifically 1,000 to 7,000. Within this range, the adhesive film may easily achieve the peel strength and modulus of the present invention while exhibiting good wettability.

When preparing urethane adhesive, polyether polyol may be present in an amount of 50 wt % to 100 wt %, more specifically 50 wt % to 99 wt % of all polyols. Within this range, the effect of the present invention can be easily achieved.

Preferably, the polyether number average molecular weight polyol may include a mixture of a polyether number average molecular weight diol and a polyether number average molecular weight triol, thereby making it easier to achieve the effects of the present invention.

For example, when preparing a urethane adhesive, the polyether triol may be present in an amount of 50% to 95% by weight, such as 50% to 90% by weight, of all polyols, and the polyether diol may be present in an amount of 5% to 50% by weight, such as 5% to 40% by weight, or 10% to 50% by weight of all polyols. Within this range, the effects of the present invention can be easily achieved.

In one embodiment, the polyether diol may have a number average molecular weight of 400 to 10,000, specifically 1,000 to 6,000. Within this range, the adhesive film can easily achieve the peeling strength of the present invention while exhibiting good wettability.

In one embodiment, the polyether triol may have a number average molecular weight of 400 to 10,000, specifically 2,000 to 8,000. Within this range, the adhesive film can easily achieve the peeling strength of the present invention while exhibiting good wettability.

In one embodiment, the urethane adhesive can be formed by a polyol comprising 50 wt % to 95 wt % of a polyether triol and 5 wt % to 50 wt % of a polyether diol and at least one polyisocyanate compound. Within this range, the effects of the present invention can be easily achieved.

The polyester-based polyol may include a polyol obtained by esterification between at least one polyol and at least one acid component.

The polyol used herein may include at least one selected from the group consisting of ethylene glycol, propylene glycol, diethylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2-butyl-2-ethyl-1,3-propanediol, 2,4-diethyl-1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 2-ethyl-1,3-hexanediol, 1,8-octanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol, 1,8-decanediol, octadecanediol, glycerol, trihydroxymethylpropane, pentaerythritol, and hexanetriol, but is not limited thereto. The acid component used herein may include succinic acid, methylsuccinic acid, adipic acid, azelaic acid, sebacic acid, 1,12-dodecanoic acid, 1,14-tetradecanoic acid, dimer acid, 2-methyl-1,4-cyclohexanedicarboxylic acid, 2-ethyl-1,4-cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalene dicarboxylic acid, 4,4'-biphenyl dicarboxylic acid and anhydrides thereof, but are not limited thereto.

When preparing a urethane adhesive, a polyester polyol may be used alone or in combination of two or more polyester polyols.

The polyester polyol (eg, polyester diol) may have a number average molecular weight of 1,000 to 5,000, specifically 2,000 to 3,000. Within this range, it may be advantageous to achieve the peel strength and modulus of the present invention.

When preparing the urethane adhesive, the polyester polyol may be present in an amount of 0 wt % to 50 wt %, specifically 1 wt % to 50 wt %, and more specifically 5 wt % to 40 wt % of the total polyol. Within this range, the effects of the present invention can be easily achieved.

The polyester polyol may include a polyester polyol having two or more hydroxyl groups, such as a difunctional polyester polyol (polyester diol) and/or a trifunctional polyester polyol (polyester triol). Thus, the urethane binder becomes a hyperbranched binder, thereby contributing to achieving the effect of the present invention. Preferably, polyester diol is used as the polyester polyol.

In one embodiment, the urethane binder can be formed from a mixture comprising: a polyol comprising 50 wt % to 90 wt % (e.g., 50 wt %, 51 wt %, 52 wt %, 53 wt %, 54 wt %, 55 wt %, 56 wt %, 57 wt %, 58 wt %, 59 wt %, 60 wt %, 61 wt %, 62 wt %, 63 wt %, 64 wt %, 65 wt %, 66 wt %, 67 wt %, 68 wt %, 69 wt %, 70 wt %, 71 wt %, 72 wt %, 73 wt %, 74 wt %, 75 wt %, 76 wt %, 77 wt %, 78 wt %, 79 wt %, 80 wt %, 81 wt %, 82 wt %, 83 wt %, 84 wt %, 85 wt %, 86 wt %, 87 wt %, 88 wt %, 89 wt %, 90 wt %, 91 wt %, 92 wt %, 93 wt %, 94 wt %, 95 wt %, 96 wt %, 97 wt %, 98 wt %, 99 wt %, 100 wt %, 101 wt %, 102 4 wt %, 75 wt %, 76 wt %, 77 wt %, 78 wt %, 79 wt %, 80 wt %, 81 wt %, 82 wt %, 83 wt %, 84 wt %, 85 wt %, 86 wt %, 87 wt %, 88 wt %, 89 wt %, 90 wt %) of a polyether triol, 5 wt % to 40 wt % (e.g., 5 wt %, 6 wt %, 7 wt %, 8 wt %, 9 wt %, 10 wt %, 11 wt %, 12 wt %, 13 wt %, 14 wt %, 15 wt %, 16 wt %, 17 wt %, 18 wt %, 19 wt %, 20 wt %, 21 wt %, 22 wt %, 23 wt %, 24 wt %, 25 wt %, 26 wt %, 27 wt %, 28 wt %, 29 wt %, 30 wt %, 31 wt %, 32 wt %, 33 wt %, 34 8 wt %, 19 wt %, 20 wt %, 21 wt %, 22 wt %, 23 wt %, 24 wt %, 25 wt %, 26 wt %, 27 wt %, 28 wt %, 29 wt %, 30 wt %, 31 wt %, 32 wt %, 33 wt %, 34 wt %, 35 wt %, 36 wt %, 37 wt %, 38 wt %, 39 wt %, 40 wt %) of a polyether glycol and 5 wt % to 40 wt % (e.g., 5 wt %, 6 wt %, 7 wt %, 8 wt %, 9 wt %, 10 wt %, 11 wt %, 12 wt%, 13 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, 20 wt%, 21 wt%, 22 wt%, 23 wt%, 24 wt%, 25 wt%, 26 wt%, 27 wt%, 28 wt%, 29 wt%, 30 wt%, 31 wt%, 32 wt%, 33 wt%, 34 wt%, 35 wt%, 36 wt%, 37 wt%, 38 wt%, 39 wt%, 40 wt%) of polyester diol; and at least one polyisocyanate compound. Within this range, the effects of the present invention can be easily achieved.

The polyisocyanate compound may include a polyisocyanate compound having a plurality of isocyanate groups (-NCO). The polyisocyanate compound may be selected from any polyisocyanate compound known to those skilled in the art, and may include at least one selected from aliphatic polyisocyanates, alicyclic polyisocyanates, aromatic polyisocyanates, and aromatic-aliphatic polyisocyanates. Preferably, the polyisocyanate compound is an aliphatic polyisocyanate.

The aliphatic polyisocyanate may include at least one selected from the group consisting of hexamethylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, 1,2-propyl diisocyanate, 2,3-butyl diisocyanate, 1,3-butyl diisocyanate, dodecamethylene diisocyanate, and 2,4,4-trimethylhexamethylene diisocyanate, but is not limited thereto.

Relative to 100 parts by weight of all polyols, the polyisocyanate compound may be present in the following amount: 1 part by weight to 10 parts by weight, such as 1 part by weight, 2 parts by weight, 3 parts by weight, 4 parts by weight, 5 parts by weight, 6 parts by weight, 7 parts by weight, 8 parts by weight, 9 parts by weight, 10 parts by weight, specifically 1 part by weight to 6 parts by weight, more specifically 1 part by weight to 5.5 parts by weight. Within this range, the urethane adhesive according to the present invention can be easily prepared.

The reaction can be performed by adding a catalyst to a mixture of at least one polyol and at least one polyisocyanate compound, and then reacting the mixture at a predetermined temperature.

The catalyst may be a tin compound, and may include dibutyl tin dilaurate (DBTDL), 2-ethylhexanoic acid tin, etc., but is not limited thereto.

The urethane adhesive can be prepared by placing a polyol mixture in a reactor and heating the mixture at 80°C to 100°C for 10 minutes (min) to 30 minutes under nitrogen purge conditions to completely remove residual moisture, lowering the internal temperature of the reactor to 65°C to 70°C, adding a polyisocyanate compound and a catalyst to the resulting product, and subjecting the resulting product to primary polymerization at 65°C to 75°C for 3 hours to 4 hours, and then subjecting the resulting product to secondary polymerization at 75°C to 85°C for 60 minutes to 120 minutes.

The curable component may further comprise a polyol.

The polyol may have at least one hydroxyl group to achieve a further reduction in the rate of variation of the peel strength.

The polyol may include at least one selected from polyether polyol, polyester polyol, polycaprolactone polyol and polycarbonate polyol. Preferably, the polyol is a polyether polyol.

The polyether polyol may be a polyether polyol having an alkylene oxide group and two or more hydroxyl groups, such as a trifunctional polyether polyol (polyether triol) or a difunctional polyether polyol (polyether diol) (such as polyethylene glycol, polypropylene glycol and polybutylene glycol), a trifunctional polyether polyol (polyether triol) of a glycerol alkylene oxide adduct, and the like.

The polyester polyol may include a polyol obtained by esterification between at least one polyol and at least one acid component. The polyol and acid component used herein are the same as those described above.

The polyol may have a number average molecular weight of 400 to 10,000, specifically 1,000 to 7,000. Within this range, the adhesive film can easily achieve the peel strength and modulus of the present invention while exhibiting good wettability.

In the curable component, the polyol may be present in an amount of 0 wt % to 40 wt %, for example, greater than 0 wt % to less than 40 wt %, or 0 wt %. Within this range, the effects can be achieved by adding the polyol.

Relative to 100 parts by weight of the urethane adhesive, the polyol may be present in an amount of 0 to 70 parts by weight, specifically 0 parts by weight. Within this range, the effect can be achieved by adding the polyol.

Curing agent

The curing agent can provide peel strength by curing the curable component.

The curing agent may have at least one isocyanate group (-NCO) which reacts with the hydroxyl group of the urethane binder and/or the polyol to form a matrix of the adhesive film and provide peel strength of the adhesive film.

The isocyanate-based curing agent may be a multifunctional isocyanate-based curing agent having a plurality of isocyanate groups, and may include any typical isocyanate-based curing agent known to those skilled in the art.

In one embodiment, the isocyanate curing agent may include at least one selected from the following: aliphatic isocyanate, alicyclic isocyanate, aromatic isocyanate, aromatic-aliphatic isocyanate, polyol adduct thereof, biuret thereof or isocyanurate thereof. For example, the aliphatic isocyanate may include at least one selected from the following: hexamethylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, 1,2-propyl diisocyanate, 2,3-butyl diisocyanate, 1,3-butyl diisocyanate, dodecamethylene diisocyanate and 2,4,4-trimethylhexamethylene diisocyanate, but is not limited thereto. For example, the aromatic isocyanate may include at least one selected from the group consisting of toluene diisocyanate, xylene diisocyanate, and phenylene diisocyanate, but is not limited thereto.

Preferably, the isocyanate curing agent comprises an isocyanurate curing agent of the isocyanurate type described above. The isocyanurate curing agent can easily achieve the effect of the present invention when combined with the composition comprising the urethane binder and the plasticizer of the present invention.

Relative to 100 parts by weight of the curable component (specifically urethane adhesive), for example 100 parts by weight of urethane adhesive, the curing agent may be present in an amount of 1 to 10 parts by weight, for example 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 parts by weight, specifically 2 to 6 parts by weight. Within this range, the curing agent can be used to form the adhesive film according to the present invention.

Plasticizer

With the plasticizer, the adhesive film can have a CI value of less than 5%. According to the present invention, the specific plasticizer described below is used in the composition according to the present invention comprising a curable component and a curing agent, wherein the adhesive film can have a CI value of less than 5%.

The plasticizer may be selected from any ester plasticizer.

In one embodiment, the ester plasticizer may have a surface tension of 27 mN/m or less, such as 20 mN/m to 27 mN/m. Within this range, the dent resistance of the adhesive film may be easily improved. The surface tension of the plasticizer may be measured using a tensiometer (KRUSS, model K11-MK1) by referring to the catalog of the corresponding product or by a typical method known to a person skilled in the art. The surface tension of the plasticizer may be measured at 25°C.

In one embodiment, the ester plasticizer may be a non-aliphatic, non-heterocycloaliphatic and non-aromatic ester plasticizer that does not contain aliphatic groups, heterocycloaliphatic groups and aromatic groups. The ester plasticizer may have a larger total number of carbons at the ester site. This structure can reduce the surface tension of the plasticizer by providing a flexible chain structure while improving the elastic properties of the urethane adhesive, thereby improving the dent resistance of the adhesive film by reducing the CI value.

In one embodiment, the plasticizer can be represented by Formula 1: X ₂ —C(═O)—OX ₁ —CH ₂ —CH(CH ₃ ) ₂ , wherein X ₁ is a linear C ₈ to C ₂₀ alkylene group, and X ₂ is a linear or branched substituted or unsubstituted C ₃ to C ₁₀ alkyl group.

In Formula 1, "substituted" in the expression "substituted or unsubstituted" means that at least one hydrogen atom in the corresponding functional group is substituted with a linear or branched _C1 to _C10 alkyl group.

For example _{, X1} is a linear C8, _C9 , _C10 , _C11 , _C12 , _C13 , _C14 , _C15 , _C16 , _C17 , _C18 , _C19 , _C20 alkylene group. For example, _X2 is a linear or branched substituted or unsubstituted C3, _{C4 ,} C5, _C6 , _{C7 , C8} , _C9 , _C10 alkyl group.

For example, the plasticizer may include at least one selected from isotridecyl isononanoate (ITDN) and tridecyl isononanoate, but is not limited thereto.

For example, the plasticizer may include at least one selected from the compounds of Formula 1-1 and Formula 1-2. [Formula 1-1] (CH ₃ ) ₂ CH-(CH ₂ ) ₅ -C(═O)-O-(CH ₂ ) ₉ -(CH ₂ )-CH(CH ₃ ) ₂ [Formula 1-2] (CH ₃ ) ₃ C-(CH ₂ )-CH(CH ₃ )-(CH ₂ )-C(═O)-O-(CH ₂ ) ₉ -(CH ₂ )-CH(CH ₃ ) ₂

The plasticizer of Formula 1 may be present in an amount of 90 parts by weight or more, specifically 99 parts by weight to 100 parts by weight, more specifically 100 parts by weight, relative to 100 parts by weight of all plasticizers in the adhesive film according to the present invention. Within this range, the effects of the present invention can be easily achieved.

The adhesive film may be at least one type of plasticizer, for example, two or more types of plasticizers.

Relative to 100 parts by weight of the curable component (e.g., urethane adhesive), the plasticizer may be present in an amount of 16 to 25 parts by weight, such as 16, 17, 18, 19, 20, 21, 22, 23, 24, 25 parts by weight. Within this range, the adhesive film can easily achieve the CI value of the present invention. Preferably, the plasticizer is present in an amount of 16 to 20 parts by weight relative to 100 parts by weight of the curable component (e.g., urethane adhesive). Within this range, the adhesive film can easily achieve the CI value of the present invention and a peel strength of 2 gf/inch or less.

The composition for the adhesive film may further include at least one selected from a crosslinking catalyst, a leveling agent, an antistatic agent, an antioxidant, and a delay agent.

The crosslinking catalyst catalyzes the reaction between the curable component and the curing agent.

The crosslinking catalyst may include at least one metal catalyst. The metal catalyst may include a tin catalyst and/or a non-tin catalyst. Each of the tin catalyst and the non-tin catalyst may be selected from typical types known to those skilled in the art. For example, the tin catalyst may include dibutyltin dichloride, dibutyltin oxide, dibutyltin dilaurate, dibutyltin sulfide, dibutyltin diacetate, dibutyltin maleate, etc., but is not limited thereto.

The crosslinking catalyst may be present in an amount of 0.005 to 0.5 parts by weight, specifically 0.005 to 0.1 parts by weight, relative to 100 parts by weight of the curable component (e.g., urethane adhesive). Within this range, the crosslinking catalyst can ensure a satisfactory pot life and rapid curing of the adhesive film.

Leveling agents can improve the leveling properties of adhesive films. Leveling agents may include acrylic leveling agents, fluorinated leveling agents, silicone leveling agents, silicone-acrylate leveling agents, etc.

The leveling agent may be present in an amount of 0.1 to 5 parts by weight, specifically 0.1 to 1 part by weight, relative to 100 parts by weight of the curable component (e.g., urethane adhesive). Within this range, the leveling agent can ensure a low initial peel strength of the adhesive film.

The antistatic agent can prevent damage to the adherend by suppressing the generation of static electricity in the process of peeling the adhesive film from the adherend after the adhesive film is attached to the adherend. The antistatic agent can include a typical antistatic agent known to those skilled in the art. For example, the antistatic agent can include an ionic liquid.

The antistatic agent may be present in an amount of 0.01 to 5 parts by weight, specifically 0.01 to 1 part by weight, relative to 100 parts by weight of the curable component (e.g., urethane adhesive). Within this range, the antistatic agent can provide antistatic performance without affecting the properties of the adhesive film.

The antioxidant can prevent the adhesive film from being affected by the external environment, thereby inhibiting the detachment of the adhesive film to ensure its peeling strength. The antioxidant can include typical antioxidants known to those skilled in the art. For example, the antioxidant can include cinnamate antioxidants, phenolic antioxidants, sulfur antioxidants, phosphorus antioxidants, HALS antioxidants, etc.

The antioxidant may be present in an amount of 0.01 to 5 parts by weight, specifically 0.01 to 1 part by weight, relative to 100 parts by weight of the curable component (e.g., urethane adhesive). Within this range, the antioxidant can provide antioxidant performance without affecting the properties of the adhesive film.

The delay agent may comprise any typical delay agent known to those skilled in the art. For example, the delay agent may comprise acetylacetone or a complex thereof.

The retarder may be present in an amount of 0.01 to 5 parts by weight, specifically 0.01 to 3 parts by weight, relative to 100 parts by weight of the curable component (e.g., urethane adhesive). Within this range, the retarder can provide a retarding property without affecting the properties of the adhesive film.

The composition for the adhesive film may further include additives. The additives may include UV absorbers, UV stabilizers, heat stabilizers, surfactants, fillers, pigments, etc., but are not limited thereto.

The adhesive film may be prepared by depositing a composition for an adhesive film onto a base film to a predetermined thickness to form a coating layer, and drying the coating layer at 110° C. to 140° C., followed by aging at 30° C. to 70° C. for 1 day to 3 days, but is not limited thereto. After drying the coating layer, a release film may be stacked on the coating layer, followed by aging.

An adhesive sheet according to one embodiment of the present invention comprises an adhesive film for surface protection according to an embodiment of the present invention. In one embodiment, the adhesive sheet may comprise an adhesive film for surface protection, a base film stacked on one surface of the adhesive film for surface protection, and a release film stacked on the other surface of the adhesive film for surface protection.

1 , the adhesive sheet includes an adhesive film 10 for surface protection, a base film 20 stacked on one surface of the adhesive film 10 , and a release film 30 stacked on the other surface of the adhesive film 10 .

The base film 20 can serve as a substrate to which the composition is applied when the adhesive film is formed using the composition for the adhesive film. The base film can be any typical polymer film known to those skilled in the art. For example, the base film may include at least one selected from the following: polyester resins, including polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, etc.; acrylic resins; cyclic olefin polymer (COP) resins; cellulose ester resins, including triacetylcellulose (TAC), etc.; polyvinyl acetate resins; polyvinyl chloride (PVC) resins; polynorbornene resins; polycarbonate (PC) resins; polyamide resins; polyacetal resins; polyphenylene ether resins; polyphenylene sulfide (PPS) resins. The substrate film may have a thickness of 10 μm to 200 μm, for example, 50 μm to 100 μm.

The release film 30 is used to prevent the coating layer formed by the composition for an adhesive film from being contaminated by foreign matter when the composition for an adhesive film is used to form an adhesive film. The release film may be a typical polymer film known to those skilled in the art. For example, the release film may include at least one selected from the following: polyester resin, including polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, etc.; acrylic resin; cycloolefin polymer (COP) resin; cellulose ester resin , including triacetyl cellulose (TAC) and the like; polyvinyl acetate resin; polyvinyl chloride (PVC) resin; polynorbornene resin; polycarbonate (PC) resin; polyamide resin; polyacetal resin; polyphenylene ether resin; polyphenylene sulfide resin; polysulfide resin; polyethersulfide resin; polyarylate resin; and polyimide resin. The release film may have a thickness of 10 μm to 200 μm, for example, 50 μm to 100 μm. The release film 30 may have at least one surface that is release-treated with silicone or fluorine to facilitate peeling from the adhesive film.

Next, a method of using the adhesive sheet will be described.

When the release film is removed from the adhesive sheet, the adhesive film of the adhesive sheet is bonded to the adherend. Then, when the adherend is no longer required to be protected, the adhesive film and the base film for surface protection are all removed from the adherend.

An optical component according to one embodiment of the present invention includes an optical film and an adhesive film for surface protection formed on at least one side of the optical film, wherein the adhesive film for surface protection includes the adhesive film for surface protection according to an embodiment of the present invention.

The optical film may include a polyimide film as a display panel. In one embodiment, the optical film may include a light-emitting element layer and a polyimide film formed on at least one surface of the light-emitting element layer. An organic insulating film or an inorganic insulating film may be further inserted between the optical film and the silicone adhesive protective film.

The optical component may further include a base film on the other surface of the adhesive film for surface protection. The base film can prevent the adhesive protective film from being contaminated by external foreign matter, etc. The base film can be an optical film formed by the same type of material as the optical film described above or a material of a different type from the optical film. For example, the base film can be a film formed by at least one selected from the following items: polyethylene terephthalate resin, polycarbonate resin, polyimide resin, poly (meth) acrylate resin, cycloolefin polymer resin and acrylic resin. The base film can have a thickness of 10 microns to 200 microns, for example, 50 microns to 100 microns. Within this range, the base film can support the adhesive protective film.

Next, the present invention will be described in more detail with reference to examples. However, it should be understood that these examples are provided for illustration only and should not be interpreted as limiting the present invention in any way.

Preparation Example 1

In a 1,000 ml jacketed reactor, 70 parts by weight of polyether polyol (PPG-3020), 15 parts by weight of polyether polyol (PPG-6000) and 15 parts by weight of polyester polyol (P-2010) were placed and mixed under nitrogen purge. Then, toluene was added to the mixture, and then the mixture was stirred for 10 minutes, and then the mixture was heated to 85°C for 30 minutes under nitrogen purge to remove residual moisture. The internal temperature of the reactor was lowered to 60°C and 4.5 parts by weight of hexamethylene diisocyanate (HDI) was added thereto. After further stirring the reactor at 60° C. for 10 minutes, 0.3 parts by weight of a polymerization catalyst (dibutyltin dilaurate (DBTDL)) was added to the mixture. After 1 hour, the internal temperature of the reactor was increased to 70° C., and then again increased to 80° C. after another hour, followed by polymerization at 80° C. for 2 hours. Finally, a solution containing 65% by weight of a urethane binder in terms of solid content was obtained by diluting the resulting binder solution with toluene.

Preparation Example 2 To preparation example 3

A urethane adhesive was prepared in the same manner as in Preparation Example 1, except that each component of Preparation Example 1 was changed as listed in Table 1.

Table 1 PPG-3020 PPG-6000 P-2010 HDI DBTDL Mw (g/mol) Preparation Example 1 70 15 15 4.5 0.3 80,000 Preparation Example 2 70 15 15 5.1 0.3 100,000 Preparation Example 3 70 15 15 5.9 0.3 150,000

Examples 1

The composition for adhesive film including the components of Table 2 (in terms of solid content) was prepared by the following operation: 100 parts by weight of the urethane adhesive prepared in Preparation Example 1, 4.6 parts by weight of an isocyanate curing agent (Coronate HX), 0.23 parts by weight of a leveling agent (BYK-3700), 16.9 parts by weight of a plasticizer (isotridecyl isonanoate (ITDN)), 0.25 parts by weight of an antioxidant (Irganox 1010), and 0.25 parts by weight of an aqueous solution of 1% ethanol. 1010)), 0.01 parts by weight of a crosslinking catalyst (catalyst S, dibutyltin dilaurate (DBTDL)) and 7.7 parts by weight of a delay agent (acetylacetone) were mixed, and then toluene was added to the mixture as a solvent. The prepared composition was deposited on the upper surface of a base film (PET film, thickness: 75 μm, TU67A, SKC) to a thickness of 75 μm using a coater and dried at 130°C for 4 minutes. Thereafter, a release film (PET film, thickness: 50 μm, product name: L3T, Youlchon Co., Ltd.) was attached to the coating layer and left to stand at 50° C. for 2 days, thereby preparing an adhesive film in which a base film, an adhesive film for surface protection (thickness: 75 μm), and a release film were sequentially stacked in the order stated.

Examples 2 To example 5

An adhesive sheet was prepared in the same manner as in Example 1, except that the type and/or content of each component in Example 1 was changed as listed in Table 2. In Table 2, "-" means that the corresponding component does not exist and each component is expressed in parts by weight.

Comparison Examples 1 To compare examples 6

An adhesive sheet was prepared in the same manner as in Example 1, except that the type and/or content of each component in Example 1 was changed as listed in Table 2. In Table 2, "-" means that the corresponding component does not exist and each component is expressed in parts by weight.

Table 2 Examples Comparison Examples 1 2 3 4 5 1 2 3 4 5 6 Urethane adhesive Preparation Example 1 100 100 100 - 100 100 100 100 - - 100 Preparation Example 2 - - - 100 - - - - - - - Preparation Example 3 - - - - - - - - 100 100 - Curing agent 4.6 4.6 4.6 4.6 4.6 4.6 4.6 4.6 4.6 4.6 4.6 Leveling agent 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.23 Plasticizer ITDN 16.9 18.5 20 18.5 21.5 15.4 - - - - - IPM - - - - - - 18.5 - 18.5 - - DINCH - - - - - - - 18.5 - 18.5 - DINPH - - - - - - - - - - 18.5 Dent resistance ○ ◎ ◎ ◎ ◎ △ X X X X X CI value 4.7 4.1 3.2 2.3 2.9 5.9 8.7 10.2 7.5 9.1 11.9 Peel strength 1.42 1.35 1.24 0.95 0.75 1.69 1.2 1.37 1.09 1.2 1.05 Appearance after testing at high temperature/humidity good good good good good good good good good good good Bubble generation ○ ○ ○ ○ △ X X X X X X

Table 3 shows the components used in the examples and comparative examples.

Table 3 Manufacturer Solid content Number average molecular weight PPG-3020 (polyether triol) Jinhu Petrochemical 100% 3,000 PPG-6000 (polyether glycol) Jinhu Petrochemical 100% 6,000 P-2010 (Polyester diol) Kuraray 100% 3,000 Hexamethylene diisocyanate Tokyo Chemical Industry 100% - Coronate HX (isocyanurate type) TOSOH 100% - BYK-SILCLEAN 3700 BYK 25% - ITDN (isotridecyl isonanoate) (surface tension: 26.2 mN/m) Higher alcohol industry 100% - IPM (isopropyl myristate) (surface tension: 28.5 mN/m) BASF 100% - DINCH (Di-isononyl 1,2-cyclohexanedicarboxylate) (Surface tension: 31.1 mN/m) BASF 100% - DINPH (Diisononyl phthalate) (surface tension: 35 mN/m) Merck 100% - Yanjanox 1010 BASF 100% - Catalyst S General Research 100% - Acetoacetone Oi Chemical Industry 100% -

The compositions of the adhesive films for surface protection and/or the properties of the adhesive films for surface protection prepared in the Examples and Comparative Examples were evaluated by the following methods.

(1) Indentation resistance (no unit): Each of the adhesive sheets prepared in the examples and comparative examples was cut into a size of 100 mm × 50 mm (length × width), and then the release film was peeled off from the adhesive sheet in which the base film, the adhesive film for surface protection (thickness: 75 μm), and the release film were stacked in this order. Next, the adhesive film of the adhesive sheet was bonded to a black acrylic substrate (CL-885, thickness: 1,000 μm to 2,000 μm, Nitto Jushi Kogyo), thereby preparing a sample having a cross section as shown in FIG. 2. Referring to FIG. 2 , the pit resistance of a sample including a black acrylic substrate 1, an adhesive film 2 for surface protection, and a base film 3 stacked therein in sequence was evaluated. Under conditions of 23° C. and 50% RH, with the ball head 4 of the nanoindenter placed at the center of the base film 3 of the sample (wherein the portion of the ball head contacting the base film has a spherical shape with a diameter of 0.4 mm), the sample was gradually pressed with the ball head for 20 seconds until the pressing load of the ball head reached 600 millinewtons, and maintained at this load for 5 seconds, followed by release of the force. Then, the presence of the pit was evaluated by visually observing the pressed shape on the surface of the black acrylic substrate adjacent to the adhesive film. FIG3 shows a sample having no pits or pits that are difficult to observe, and FIG4 shows a sample having clearly visible pits. Referring to FIG3, there are no pits at the center of the sample, whereas, referring to FIG4, there are wavy pits at the center of the sample. ◎: No pits ○: Can be used because the pits are extremely small and difficult to see. △: Cannot be used because there are many pits. X: Cannot be used because the pits are clearly visible.

(2) CI value (unit: %): A sample was prepared in the same manner as in (1). With the ball head 4 of the nanoindenter placed at the center of the basement membrane 3 of the sample (wherein the portion of the ball head contacting the basement membrane had a spherical shape with a diameter of 0.4 mm), the sample was gradually pressed with the ball head for 20 seconds until the pressing load of the ball head reached 600 mN, and maintained at this load for 5 seconds, and then the force was released to obtain the CI value by automatic calculation using the nanoindenter.

(3) Peel strength (unit: g-f/inch): Each of the adhesive sheets prepared in Examples and Comparative Examples was cut into a size of 200 mm×25 mm (length×width), and the release film was removed from the adhesive sheet to expose the adhesive film of the adhesive sheet in which a base film, an adhesive film for surface protection (thickness: 75 μm), and a release film were stacked in sequence. Thereafter, as an adherend, an alkali-free glass plate was bonded to the exposed surface of the adhesive film and pressed by reciprocating a 2 kg roller thereon three times, thereby preparing a sample comprising an alkali-free glass plate, an adhesive film, and a base film stacked in sequence in the order stated.

When the adhesive film was peeled off from an alkali-free glass plate, the peel strength of the sample was measured using a tensile tester (Texture Analyzer, TA Industry) at 25°C and 50% RH under the conditions of a peeling speed of 2,400 mm/min and a peeling angle of 180°. The peel strength was measured three times and then averaged.

(4) Appearance after test under high temperature/humidity conditions (elution of plasticizer) (no unit): The laminate of release film/adhesive film for surface protection/base film prepared in each of Examples and Comparative Examples was left to stand at 85°C and 85% RH for 250 hours. The elution of the plasticizer on the surface of the adhesive film was checked. The elution of the plasticizer was checked with the naked eye. The sample having a clean surface of the adhesive film due to no elution of the plasticizer was evaluated as "good", and the sample having an unclean surface of the adhesive film due to the elution of the plasticizer was evaluated as "poor".

(5) Bubble generation (no unit): The release film was removed from the laminate of the release film/adhesive film for surface protection/base film prepared in each of the Examples and Comparative Examples to expose the adhesive film, which was then bonded to a polyimide film as an adherend. The edge of each of the samples was observed while the sample was cut with a laser beam. The sample with no delamination and no bubble generation at the edge was evaluated as ○, the sample with slight delamination and bubble generation at the edge was evaluated as △, and the sample with severe delamination and bubble generation at the edge was evaluated as X.

As shown in Table 2, the adhesive film for surface protection according to the present invention exhibits good dent resistance, has peel strength to protect the adherend, can be removed from the adherend without deforming and/or damaging the adherend when removed from the adherend after being bonded to the adherend, does not generate bubbles due to delamination at its edge when cutting the laminate of the adhesive film and the adherend, and exhibits good appearance even after being left for a long time under high temperature/humidity conditions.

On the other hand, the adhesive film prepared in the comparative example failed to provide the effects of the present invention.

It should be understood that those skilled in the art can make various modifications, changes, alterations and equivalent embodiments without departing from the spirit and scope of the present invention.

1: Black acrylic substrate 2, 10: Adhesive film for surface protection 3, 20: Base film 4: Ball head 30: Release film

FIG. 1 is a cross-sectional view of an adhesive sheet including an adhesive film for surface protection according to the present invention. FIG. 2 is a cross-sectional view of a sample used for measuring pitting resistance and CI value. FIG. 3 is a picture showing a sample having no pits or having pits that are difficult to observe when evaluating pitting resistance. FIG. 4 is a picture showing a sample having clearly visible pits when evaluating pitting resistance.

Claims (17)

An adhesive film for surface protection includes a cured product of a composition for an adhesive film, the composition including: a curable component including a urethane adhesive; a curing agent; and a plasticizer, wherein the adhesive film for surface protection has a creep indentation value of less than 5%, wherein the plasticizer is represented by Formula 1: _X2 -C(=O)-OX1- _CH2 - _CH ( _CH3 ) ₂ , wherein _X1 is a linear _C8 to _C20 alkylene group, and _X2 is a linear or branched substituted or unsubstituted _C3 to _C10 alkyl group, wherein the plasticizer is present in an amount of 16 to 25 parts by weight relative to 100 parts by weight of the curable component. An adhesive film for surface protection as described in claim 1, wherein the adhesive film for surface protection has a peeling strength of 2 gf/inch or less. The adhesive film for surface protection as described in claim 1, wherein the plasticizer has a surface tension of 27 mN/m or less. The adhesive film for surface protection as described in claim 1, wherein the plasticizer is a non-alicyclic, non-hetero-alicyclic and non-aromatic plasticizer. The adhesive film for surface protection as described in claim 1, wherein the plasticizer of Formula 1 is present in an amount of 90 parts by weight or more relative to 100 parts by weight of all plasticizers in the adhesive film for surface protection. The adhesive film for surface protection as described in claim 1, wherein the plasticizer includes at least one selected from isotridecyl isonanoate and tridecyl isonanoate. The adhesive film for surface protection as described in claim 1, wherein the plasticizer includes at least one selected from the compound of Formula 1-1 and the compound of Formula 1-2, [Formula 1-1] (CH ₃ ) ₂ CH-(CH ₂ ) ₅ -C(=O)-O-(CH ₂ ) ₉ -(CH ₂ )-CH(CH ₃ ) ₂ [Formula 1-2] (CH ₃ ) ₃ C-(CH ₂ )-CH(CH ₃ )-(CH ₂ )-C(=O)-O-(CH ₂ ) ₉ -(CH ₂ )-CH(CH ₃ ) ₂ . The adhesive film for surface protection as described in claim 1, wherein the urethane adhesive has a weight average molecular weight (Mw) of greater than 60,000 g/mol to less than 150,000 g/mol. An adhesive film for surface protection as described in claim 1, wherein the urethane adhesive includes units derived from polyether polyols. An adhesive film for surface protection as described in claim 9, wherein the polyether polyol comprises at least one selected from a difunctional polyether polyol having an alkylene oxide group, a trifunctional polyether polyol having an alkylene oxide group, and a trifunctional polyether polyol of a glycerol alkylene oxide adduct. The adhesive film for surface protection as described in claim 9, wherein the urethane adhesive further includes units derived from polyester polyols. The adhesive film for surface protection as described in claim 11, wherein the polyester polyol includes at least one selected from difunctional polyester polyol and trifunctional polyester polyol. An adhesive film for surface protection as described in claim 1, wherein the curing agent includes isocyanurate of an isocyanate curing agent. The adhesive film for surface protection as described in claim 1, wherein the composition comprises, based on solid content, 100 parts by weight of the curable component, 1 to 10 parts by weight of the curing agent, and 16 to 25 parts by weight of the plasticizer. The adhesive film for surface protection as described in claim 1, wherein the composition further includes at least one selected from a crosslinking catalyst, a leveling agent, an antistatic agent, an antioxidant, and a delay agent. An adhesive sheet comprising the adhesive film for surface protection as described in any one of claims 1 to 15. An optical component, comprising: an optical film; and an adhesive film for surface protection as described in any one of claims 1 to 15, formed on at least one surface of the optical film.

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