KR20230004078A - Pressure-sensitive adhesive compositions, protective films, optical device and liquid crystal display - Google Patents

Abstract

The present application relates to a pressure-sensitive adhesive composition capable of forming a pressure-sensitive adhesive layer having an excellent adhesive strength balance while providing appropriate low-speed peel strength and high-speed peel strength, suppressing a zipping phenomenon, preventing adherend contamination, and having antistatic performance. In addition, the present application relates to a protective film including the pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive composition, an optical element including the protective film, and a liquid crystal display device including the optical element.

Description

Pressure-sensitive adhesive compositions, protective films, optical device and liquid crystal display}

This application relates to a pressure-sensitive adhesive composition, a protective film, an optical element, and a liquid crystal display device.

In the manufacturing process of optical materials, such as a polarizing plate and a retardation plate which are materials which comprise a liquid crystal display, the surface protection film for protecting the surface of the said optical material is bonded. The surface protection film is used only in the process of manufacturing the optical material, and is peeled off and removed from the optical material at the time of mounting the optical material to the liquid crystal display.

In general, a surface protection film has an adhesive layer formed on one side of an optically transparent polyalkylene terephthalate resin film, and a peeling film is bonded to the adhesive layer to protect the adhesive layer.

Since the surface protection film must protect the surface of an optical material, physical buffering and chemical resistance are basically required.

On the other hand, optical materials such as polarizers and retardation plates are subjected to product inspections involving optical evaluations such as display ability, color, contrast, and contamination of foreign substances of a liquid crystal display with the surface protective film bonded, so the surface protective film is an adhesive layer. It is required to prevent bubbles or foreign matter from adhering to.

In addition, when peeling the surface protection film from the optical material, it is required not to contaminate the optical material that is the adherend, and not to generate so-called adhesive residue.

In addition, due to static electricity generated when peeling the surface protection film from the optical material or when peeling the pressure-sensitive adhesive layer from the adherend, it affects the electric control circuit of the liquid crystal display. To prevent this, the pressure-sensitive adhesive layer Excellent antistatic performance is required.

The surface protection film protects the surface of the optical material, but if the surface protection film is peeled off during a process, the surface of the optical material may no longer be protected. For this reason, so that the surface protection film is not easily peeled off during the process, the pressure-sensitive adhesive layer of the surface protection film is required to have adequate adhesive strength, so-called low-speed peeling.

In addition, when peeling the surface protection film from the optical material, it must be able to peel quickly. In order for the surface protection film to peel easily by high-speed peeling, appropriate adhesive force is required in so-called high-speed peeling.

If the peeling force of the surface protection film is not adequate at low speed, quality problems may occur during the process or process efficiency may be adversely affected. there is. That is, the surface protection film is required to have appropriate adhesive force according to each requirement in low-speed peeling and high-speed peeling, and when it has such appropriate adhesive force, it is said to have an adhesive force balance.

In this way, the adhesive strength is balanced in low-speed peeling and high-speed peeling, and for the prevention of the generation of adhesive residue, a (meth)acrylic acid ester monomer having an alkyl group, a copolymerizable monomer containing a hydroxyl group, a copolymerizable monomer containing a carboxyl group, and an alkyl An acrylic polymer having a weight average molecular weight of about 500,000 g/mol by copolymerizing a len glycol mono(meth)acrylic acid ester monomer; And a crosslinking agent containing a bifunctional or higher functional pentamethylene diisocyanate compound; a pressure-sensitive adhesive composition containing a surface protection film including a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition is known (see Patent Document 1).

When peeling the surface protection film from the optical material, alternating peeling of a strong adhesive force portion and a weak adhesive force portion appears in a micro-unit local area. , At this time, the noise is referred to as a zipping phenomenon.

The zipping phenomenon may occur when the pressure-sensitive adhesive layer and the adherend are not adhered with uniform adhesive strength, but there are strong adhesive strength and weak adhesive strength, and the difference in adhesive strength exceeds a critical point.

The zipping phenomenon occurs because the pressure-sensitive adhesive layer and the adherend are attached with non-uniform adhesive strength, and when the surface protection film is peeled off from the optical material, if the zipping phenomenon occurs, part of the adhered portion with high adhesive strength remains on the adherend, This causes adhesive residues such as peeling lines.

A pressure-sensitive adhesive composition capable of forming a pressure-sensitive adhesive layer having an adhesive force balance, suppressing contamination of an adherend, and having antistatic performance while suppressing a zipping phenomenon has been required.

Republic of Korea Patent Publication No. 10-2016-0143501

The present application relates to a pressure-sensitive adhesive composition capable of forming a pressure-sensitive adhesive layer having antistatic performance while providing appropriate low-speed peel force and high-speed peel force, having an excellent adhesive force balance, suppressing a zipping phenomenon, and preventing adherend contamination. it's about

In addition, the present application relates to a pressure-sensitive adhesive composition, a protective film including a pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive composition, an optical element including the protective film, and a liquid crystal display device including the optical element.

Among the physical properties mentioned in this application, if the measurement temperature affects the physical property, the corresponding physical property is a physical property measured at room temperature unless otherwise specified.

The term room temperature used in this application is a natural temperature that is not heated or cooled, for example, any temperature within the range of 10 ° C to 30 ° C, for example, about 15 ° C or higher, about 18 ° C or higher, It may mean a temperature of about 20 ° C or higher, about 23 ° C or higher, about 27 ° C or lower, or 25 ° C.

As used in this application, the terms a to b mean within the range between a and b, including a and b. For example, including a to b parts by weight is the same as meaning included within the range of a to b parts by weight.

Relative humidity, a term used in this application, is expressed as a percentage (%) of the ratio of the amount of water vapor currently contained in air in a unit volume to the maximum saturated vapor pressure that air in a unit volume can contain, It can be expressed as RH%.

Substitution, a term used in this application, means that a hydrogen atom bonded to a carbon atom of a compound is replaced with another substituent, and the position to be substituted is not particularly limited as long as the hydrogen atom is substituted, that is, the position where the substituent is substituted, and two In the case of more than one substitution, the substituents may be the same as or different from each other.

As used herein, the term substituent refers to an atom or group of atoms replacing one or more hydrogen atoms on the parent chain of a hydrocarbon. In addition, substituents are described below, but are not limited thereto, and the substituents may be further substituted with substituents described below or may not be substituted with any substituents unless otherwise specified in the present application.

An alkyl group or an alkylene group, which is a term used in this application, is a straight chain or branched chain having 1 to 20 carbon atoms, or 1 to 16 carbon atoms, or 1 to 12 carbon atoms, or 1 to 8 carbon atoms, or 1 to 6 carbon atoms, unless otherwise specified. It may be a chain alkyl group or an alkylene group, or a cyclic alkyl group or alkylene group having 3 to 20 carbon atoms, or 3 to 16 carbon atoms, or 3 to 12 carbon atoms, or 3 to 8 carbon atoms, or 3 to 6 carbon atoms. Here, the cyclic alkyl group or alkylene group includes an alkyl group or alkylene group having only a cyclic structure and an alkyl group or alkylene group having a cyclic structure. For example, both a cyclohexyl group and a methyl cyclohexyl group correspond to a cyclic alkyl group. In addition, for example, an alkyl group or an alkylene group is specifically methyl (ene), ethyl (ene), n-propyl (ene), isopropyl (ene), n-butyl (ene), isobutyl ( (ene), tert-butyl (rene), sec-butyl (ene), 1-methyl-butyl (ene), 1-ethyl-butyl (ene), n-pentyl (ene), isopentyl (ene), neopentyl (ene), tert-pentyl (ene), n-hexyl (ene), 1-methylpentyl (ene), 2-methylpentyl (ene), 4-methyl-2-pentyl (ene), 3,3-dimethyl Butyl (ene), 2-ethylbutyl (ene), n-heptyl (ene), 1-methylhexyl (ene), n-octyl (ene), tert-octyl (ene), 1-methylheptyl (ene), 2-ethylhexyl(ene), 2-propylpentyl(ene), n-nonyl(ene), 2,2-dimethylheptyl(ene), 1-ethylpropyl(ene), 1,1-dimethylpropyl(ene) , Isohexyl (ene), 2-methylpentyl (ene), 4-methylhexyl (ene), 5-methylhexyl (ene), etc. may be exemplified, but are not limited thereto. In addition, the cycloalkyl group or cycloalkylene group is specifically cyclopropyl (ene), cyclobutyl (ene), cyclopentyl (ene), 3-methylcyclopentyl (ene), 2,3-dimethylcyclopentyl (ene), cyclo Hexyl (ene), 3-methylcyclohexyl (ene), 4-methylcyclohexyl (ene), 2,3-dimethylcyclohexyl (ene), 3,4,5-trimethylcyclohexyl (ene), 4-tert -Butylcyclohexyl (ene), cycloheptyl (ene), cyclooctyl (ene), etc. may be exemplified, but are not limited thereto.

An alkenyl group or alkenylene group, which is a term used in this application, unless otherwise specified, is a straight chain or branched chain having 2 to 20 carbon atoms, or 2 to 16 carbon atoms, or 2 to 12 carbon atoms, or 2 to 8 carbon atoms, or 2 to 6 carbon atoms. chain acyclic alkenyl or alkenylene groups; It may be a cyclic alkenyl group or alkenylene group having 3 to 20 carbon atoms, or 3 to 16 carbon atoms, or 3 to 12 carbon atoms, or 3 to 8 carbon atoms, or 3 to 6 carbon atoms. Here, if a cyclic alkenyl group or alkenylene group is included, it corresponds to a cyclic alkenyl group or alkenylene group. Also, for example, ethenyl (ene), n-propenyl (ene), isopropenyl (ene), n-butenyl (ene), isobutenyl (ene), tert-butenyl (ene), sec -butenyl (rene), 1-methyl-butenyl (ene), 1-ethyl-butenyl (ene), n-pentenyl (ene), isopentenyl (ene), neopentenyl (ene), tert -Pentenyl (ene), n-hexenyl (ene), 1-methylpentenyl (ene), 2-methylpentenyl (ene), 4-methyl-2-pentenyl (ene), 3,3-dimethyl Butenyl (rene), 2-ethylbutenyl (ene), n-heptenyl (ene), 1-methylhexenyl (ene), n-octenyl (ene), tert-octenyl (ene), 1- Methylheptenyl (ene), 2-ethylhexenyl (ene), 2-propylpentenyl (ene), n-nonylenyl (ene), 2,2-dimethylheptenyl (ene), 1-ethylpropenyl ( Examples include 1,1-dimethylpropenyl (rene), isohexenyl (ene), 2-methylpentenyl (ene), 4-methylhexenyl (ene), and 5-methylhexenyl (ene). It can be, but is not limited to these. In addition, the cycloalkenyl group or cycloalkenylene group is specifically cyclopropenyl (ene), cyclobutenyl (ene), cyclopentenyl (ene), 3-methylcyclopentenyl (ene), 2,3-dimethylcyclophene tenyl(ene), cyclohexenyl(ene), 3-methylcyclohexenyl(ene), 4-methylcyclohexenyl(ene), 2,3-dimethylcyclohexenyl(ene), 3,4,5- Trimethylcyclohexenyl (ene), 4-tert-butylcyclohexenyl (ene), cycloheptenyl (ene), cyclooctenyl (ene) and the like may be exemplified, but are not limited thereto.

An alkynyl group or alkynylene group, which is a term used in this application, is a straight-chain or branched group having 2 to 20 carbon atoms, or 2 to 16 carbon atoms, or 2 to 12 carbon atoms, or 2 to 8 carbon atoms, or 2 to 6 carbon atoms, unless otherwise specified. Chain acyclic alkynyl group or alkynylene group, or a cyclic alkynyl group or alkynylene group having 3 to 20 carbon atoms, or 3 to 16 carbon atoms, or 3 to 12 carbon atoms, or 3 to 8 carbon atoms, or 3 to 6 carbon atoms it can be Here, if a cyclic alkynyl group or alkynylene group is included, it corresponds to a cyclic alkynyl group or alkynylene group. Further, for example, ethynyl (rene), n-propynyl (ene), isopropynyl (ene), n-butynyl (ene), isobutynyl (ene), tert-butynyl (ene), sec-Butynyl (Rene), 1-methyl-Butynyl (Rene), 1-Ethyl-Butynyl (Rene), n-Pentynyl (Rene), Isopentynyl (Rene), Neopentynyl (Rene), tert-pentynyl(ene), n-hexynyl(ene), 1-methylpentynyl(ene), 2-methylpentynyl(ene), 4-methyl-2-pentynyl(ene), 3,3- dimethylbutynyl(ene), 2-ethylbutynyl(ene), n-heptynyl(ene), 1-methylhexynyl(ene), n-octynyl(ene), tert-octynyl(ene), 1-Methylheptynyl (Lene), 2-Ethylheptynyl (Lene), 2-Propylpentynyl (Lene), n-Nonynyl (Lene), 2,2-Dimethylheptynyl (Lene), 1-Ethylpropy Nyl (Rene), 1,1-dimethylpropynyl (Rene), isohexynyl (Rene), 2-methylpentynyl (Rene), 4-methylhexynyl (Rene), 5-methylhexynyl ( Ren) and the like may be exemplified, but are not limited thereto. In addition, the cycloalkynyl group or cycloalkynylene group is specifically cyclopropynyl (Lene), cyclobutynyl (Lene), cyclopentynyl (Lene), 3-methylcyclopentynyl (Lene), 2,3-dimethylcyclopentyl group. Nyl(ene), cyclohexynyl(ene), 3-methylcyclohexynyl(ene), 4-methylcyclohexynyl(ene), 2,3-dimethylcyclohexynyl(ene), 3, 4,5-trimethylcyclohexynyl (ene), 4-tert-butylcyclohexynyl (ene), cycloheptynyl (ene), cyclooctynyl (ene), etc. may be exemplified. Not limited to this.

The alkyl group, alkylene group, alkenyl group, alkenylene group, and alkynyl group may optionally be substituted with one or more substituents. In this case, substituents include halogen (chlorine (Cl), iodine (I), bromine (Br), fluorine (F)), aryl group, heteroaryl group, epoxy group, alkoxy group, cyano group, carboxyl group, acryl It may be at least one selected from the group consisting of a loyl group, a methacryloyl group, an acryloyloxy group, a methacryloyloxy group, a carbonyl group, and a hydroxyl group, but is not limited thereto.

As used herein, an aryl group refers to an aromatic ring in which one hydrogen is removed from an aromatic hydrocarbon ring, and the aromatic hydrocarbon ring may include a monocyclic or polycyclic ring. The aryl group is not particularly limited in carbon atoms, but unless otherwise specified, aryl having 6 to 30 carbon atoms, or 6 to 26 carbon atoms, or 6 to 22 carbon atoms, or 6 to 20 carbon atoms, or 6 to 18 carbon atoms, or 2 to 15 carbon atoms may be In addition, the term arylene group used in this application means that the aryl group has two bonding sites, that is, a divalent group. The description of the aryl group described above may be applied except that each is a divalent group. The aryl group may be, for example, a phenyl group, a phenylethyl group, a phenylpropyl group, a benzyl group, a tolyl group, a xylyl group, or a naphthyl group, but is not limited thereto.

A heteroaryl group, a term used in this application, is an aromatic ring containing one or more heteroatoms other than carbon, and specifically, the heteroatoms include nitrogen (N), oxygen (O), sulfur (S), selenium (Se) and tele One or more atoms selected from the group consisting of nium (Te) may be included. At this time, atoms constituting the ring structure of the heteroaryl group can be referred to as a reducing group. In addition, heteroaryl groups may include monocyclic or polycyclic rings. The heteroaryl group is not particularly limited in carbon atoms, but has 2 to 30 carbon atoms, or 2 to 26 carbon atoms, or 2 to 22 carbon atoms, or 2 to 20 carbon atoms, or 2 to 18 carbon atoms, or 2 to 15 carbon atoms, unless otherwise specified. It may be a heteroaryl group. In another example, the number of reducing atoms of the heteroaryl group is not particularly limited, but may be a heteroaryl group having 5 to 30, 5 to 25, 5 to 20, 5 to 15, 5 to 10, or 5 to 8 reducing atoms. The heteroaryl group is, for example, a thiophene group, a furan group, a pyrrole group, an imidazolyl group, a thiazolyl group, an oxazolyl group, an oxadiazolyl group, a triazolyl group, a pyridyl group, and a bipyridyl group. , Pyrimidyl group, triazinyl group, acridyl group, pyridazinyl group, pyrazinyl group, quinolinyl group, quinazolinyl group, quinoxalinyl group, phthalazinyl group, pyridopyrimidinyl group, pyridopyrazinyl group , Pyrazinopyrazinyl group, isoquinolinyl group, indole group, carbazolyl group, benzoxazolyl group, benzimidazolyl group, benzothiazolyl group, benzocarbazolyl group, dibenzocarbazolyl group, benzothiophene group , Dibenzothiophene group, benzofuran group, dibenzofuran group, benzosilol group, dibenzosilol group, phenanthrolinyl group, isoxazolyl group, thiadiazolyl group, phenothiazinyl group, phenoxazine group And condensation structures thereof may be exemplified, but are not limited thereto.

In addition, the term heteroarylene group used in this application means a heteroaryl group having two bonding sites, that is, a divalent group. The above description of the heteroaryl group may be applied except that each is a divalent group.

The aryl group or heteroaryl group may be optionally substituted with one or more substituents. In this case, substituents include halogen (chlorine (Cl), iodine (I), bromine (Br), fluorine (F)), aryl group, heteroaryl group, epoxy group, alkoxy group, cyano group, carboxyl group, acryl It may be at least one selected from the group consisting of a loyl group, a methacryloyl group, an acryloyloxy group, a methacryloyloxy group, a carbonyl group, and a hydroxyl group, but is not limited thereto.

As used in this application, the term (meth)acrylate refers to acrylic acid, methacrylic acid, a derivative of acrylic acid or a derivative of methacrylic acid.

Weight average molecular weight (Mw) and number average molecular weight (Mn), which are terms used in this application, can be measured using GPC (Gel permeation chromatography), and can be specifically measured according to the physical property measurement method below. In addition, the term polydispersity index (PDI) used in this application is a value obtained by dividing the weight average molecular weight (Mw) by the number average molecular weight (Mn) (Mw/Mn), and refers to the distribution of the molecular weight of a polymer. .

Viscosity, which is a term used in this application, may be a value measured at room temperature, and may be specifically measured according to the method for measuring physical properties below.

adhesive composition

The pressure-sensitive adhesive composition according to an example of the present application may include a first acrylic polymer and a second acrylic polymer.

The pressure-sensitive adhesive composition according to an example of the present application may include 80% by weight or more, 82% by weight or more, 84% by weight or more, 86% by weight or more, 88% by weight or more, or 90% by weight or more of the first acrylic polymer, In another example, it may include 99.9% by weight or less, 99.5% by weight or less, or 99% by weight or less. The content ratio of the first acrylic polymer may be included within the range formed by the upper and lower limits listed above.

The pressure-sensitive adhesive composition according to an example of the present application may include the second acrylic polymer in an amount of 0.01 parts by weight or more, 0.025 parts by weight or more, 0.05 parts by weight or more, 0.075 parts by weight or more, or 0.1 parts by weight or more based on 100 parts by weight of the first acrylic polymer. In another example, it may be included in 5 parts by weight or less, 4 parts by weight or less, 3 parts by weight or less, 2 parts by weight or less, or 1 part by weight or less based on 100 parts by weight of the first acrylic polymer. The content ratio of the second acrylic polymer may be included within the range formed by the upper and lower limits listed above.

First acrylic polymer

The first acrylic polymer of the pressure-sensitive adhesive composition according to an example of the present application may have a weight average molecular weight of 200,000 g/mol or more, 250,000 g/mol or more, 300,000 g/mol or more, 350,000 g/mol or more, or 400,000 g/mol or more . The weight average molecular weight of the first acrylic polymer may be included within the range formed by the upper and lower limits listed above.

In addition, the first acrylic polymer may have a polydispersity index (PDI) of 1.5 or more, 2 or more, 2.5 or more, 3 or more, or 3.5 or more, and in other examples, 10 or less, 9.5 or less, 9 or less, 8.5 or less, 8 or less, or It may be less than 7.5. The polydispersity index (PDI) of the first acrylic polymer may be included within the range formed by the upper and lower limits listed above.

In addition, the first acrylic polymer may have a viscosity measured at room temperature of 1,000 cPs or more, 1,250 cPs or more, 1,500 cPs or more, 1,750 cPs or more, or 2,000 cPs or more, and in another example, the viscosity measured at room temperature is 8,000 cPs or less, 7,000 cPs or less, 6,000 cPs or less, 5,000 cPs or less, or 4,000 cPs or less. The viscosity of the first acrylic polymer measured at room temperature may be included within the range formed by the upper and lower limits listed above.

When the weight average molecular weight, polydispersity index and/or viscosity of the first acrylic polymer satisfies the aforementioned ranges, an adhesive layer having excellent adhesiveness balance and suppressing zipping and durability reduction can be formed.

The first acrylic polymer of the pressure-sensitive adhesive composition according to an example of the present application includes (i) an alkyl (meth)acrylate unit having a linear or branched chain alkyl group, (ii) an alkoxy alkylene glycol (meth)acrylate unit, and (iii) hydroxyalkyl (meth)acrylate units.

(i) Alkyl (meth)acrylate units having a straight-chain or branched-chain alkyl group included in the first acrylic polymer may deteriorate the cohesive force of the cured product and make it difficult to control the glass transition temperature or adhesiveness if the included alkyl group is excessively long. Since there is, it may be preferable to use an alkyl (meth)acrylate unit having an alkyl group having 1 to 20 carbon atoms. Examples of such monomers include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, t-butyl ( meth)acrylate, sec-butyl (meth)acrylate, pentyl (meth)acrylate, 2-ethylbutyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, Isooctyl (meth)acrylate, isononyl (meth)acrylate, lauryl (meth)acrylate, tetradecyl (meth)acrylate, and the like, or a mixture of two or more, but is not limited thereto.

(i) the alkyl (meth)acrylate unit having a linear or branched chain alkyl group included in the first acrylic polymer is 80% by weight or more, 81% by weight or more, 82% by weight or more, 83% by weight or more based on the total weight of the first acrylic polymer % or more, 84 wt% or more, or 85 wt% or more, and in other examples, 97 wt% or less, 96 wt% or less, 95 wt% or less, or 94 wt% or less based on the total weight of the first acrylic polymer. . The content ratio of (i) an alkyl (meth)acrylate unit having a linear or branched chain alkyl group included in the first acrylic polymer may be included within the range formed by the upper and lower limits listed above.

When the content ratio of the (i) alkyl (meth)acrylate unit having a straight-chain or branched-chain alkyl group in the first acrylic polymer satisfies the above range, the cohesive strength of the adhesive composition can be secured, and thereby the cured product Durability degradation can be prevented.

In addition, (i) an alkyl (meth)acrylate unit having a straight-chain or branched-chain alkyl group included in the first acrylic polymer, the first unit having 5 or less carbon atoms in the straight-chain or branched-chain alkyl group, and the straight-chain or branched-chain alkyl group may include a second unit having 6 or more carbon atoms.

Here, the weight ratio (AA2/AA1) of the alkyl (meth)acrylate unit (AA1) having the first unit and the alkyl (meth)acrylate unit (AA2) having the second unit is 1 or more, 1.1 or more, or 1.2 It may be 1.3 or more, or 1.4 or more, and in other examples, it may be 5 or less, 4 or less, 3 or less, or 2 or less. The weight ratio (AA2/AA1) of the alkyl (meth)acrylate unit (AA1) having the first unit and the alkyl (meth)acrylate unit (AA2) having the second unit is the range formed by the upper and lower limits listed above. may be included in

When the weight ratio (AA2/AA1) of the alkyl (meth)acrylate unit (AA1) having the first unit and the alkyl (meth)acrylate unit (AA2) having the second unit satisfies the above range, excellent Transfer contamination occurring on the adherend after the protective film including the pressure-sensitive adhesive layer containing the cured product of the pressure-sensitive adhesive composition is separated from the adherend may be minimized while maintaining the balance of adhesive strength.

The (ii) alkoxy alkylene glycol (meth)acrylate unit included in the first acrylic polymer enables the cured product to have stable adhesive strength and at the same time to secure antistatic performance (ESD characteristics). Examples of such monomers include alkoxy monoalkylene glycol (meth)acrylate, alkoxy dialkylene glycol (meth)acrylate, alkoxy trialkylene glycol (meth)acrylate, alkoxy tetraalkylene glycol (meth)acrylate, Types of phenoxy monoalkylene glycol (meth)acrylate, phenoxy dialkylene glycol (meth)acrylate, phenoxy trialkylene glycol (meth)acrylate, and phenoxy tetraalkylene glycol (meth)acrylate. Or a mixture of two or more kinds may be mentioned, but is not limited thereto. In the above, alkoxy may represent an alkoxy having 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms, and more specifically, methoxy, ethoxy, propoxy or butoxy. In addition, the alkylene glycol in the above may be, for example, an alkylene glycol having 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms, and more specifically, ethylene glycol, propylene glycol or more polyalkyl It may be len glycol.

(ii) alkoxy alkylene glycol (meth)acrylate units included in the first acrylic polymer are (i) 1 part by weight or more, 1.5 parts by weight or more, or 2 parts by weight or more based on 100 parts by weight of alkyl (meth)acrylate units , 2.5 parts by weight or more or 3 parts by weight or more, and in another example, (i) alkyl (meth) acrylate unit 100 parts by weight compared to 15 parts by weight or less, 14.5 parts by weight or less, 14 parts by weight or less, 13.5 parts by weight Or less, 13 parts by weight or less, 12.5 parts by weight or less, or 12 parts by weight or less may be included. The content ratio of the (ii) alkoxy alkylene glycol (meth)acrylate unit included in the first acrylic polymer may be included within the range formed by the upper and lower limits listed above.

When the content of the (ii) alkoxy alkylene glycol (meth)acrylate unit contained in the first acrylic polymer satisfies the above range, the cured product has stable adhesive strength and antistatic performance (ESD property). can secure it.

The (iii) hydroxyalkyl (meth)acrylate unit included in the first acrylic polymer may allow the adhesive composition to ensure compatibility and/or flow properties. Examples of such monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 2-hydroxyethylene glycol (meth)acrylate, 2-hydroxypropylene glycol (meth)acrylate, and the like, or a mixture of two or more, but is not limited thereto not.

(iii) hydroxyalkyl (meth)acrylate units included in the first acrylic polymer are (i) 1 part by weight or more, 1.5 parts by weight or more, 2 parts by weight or more, based on 100 parts by weight of alkyl (meth)acrylate units; 2.5 parts by weight or more or 3 parts by weight or more, and in another example, (i) 10 parts by weight or less, 9 parts by weight or less, 8 parts by weight or less, 7 parts by weight or less based on 100 parts by weight of an alkyl (meth)acrylate unit or 6 parts by weight or less. The content ratio of the (iii) hydroxyalkyl (meth)acrylate unit included in the first acrylic polymer may be included within the range formed by the upper and lower limits listed above.

When the content ratio of the (iii) hydroxyalkyl (meth)acrylate unit in the first acrylic polymer satisfies the above range, the adhesive composition may have compatibility and/or flow characteristics.

In addition, as (iii) hydroxyalkyl (meth)acrylate units included in the first acrylic polymer, a third unit having 3 or less carbon atoms in the hydroxyalkyl and a fourth unit having 4 or more carbon atoms in the hydroxyalkyl can include

Here, the weight ratio (HA4/HA3) of the hydroxyalkyl (meth)acrylate unit (HA3) having the third unit and the hydroxyalkyl (meth)acrylate unit (HA4) having the fourth unit is 0.01 or more, It may be 0.05 or more, 0.1 or more, 0.15 or more, or 0.2 or more, and in other examples, it may be 1 or less, 0.9 or less, 0.8 or less, 0.7 or less, or 0.6 or less. The weight ratio (HA4/HA3) of the hydroxyalkyl (meth)acrylate unit (HA3) having the third unit and the hydroxyalkyl (meth)acrylate unit (HA4) having the fourth unit is the upper and lower limits listed above It may be included within the range formed by.

The weight ratio (HA4 / HA3) of the hydroxyalkyl (meth) acrylate unit (HA3) having the third unit and the hydroxyalkyl (meth) acrylate unit (HA4) having the fourth unit Satisfying the above range In this case, it is possible to suppress the zipping phenomenon while securing an excellent adhesive force balance.

The first acrylic polymer includes (i) an alkyl (meth)acrylate having a straight-chain or branched-chain alkyl group, (ii) an alkoxy alkylene glycol (meth)acrylate, and (iii) a hydroxyalkyl (meth)acrylate. It can be prepared by adding a monomer composition to a solvent to form a mixed composition, and adding an initiator to the mixed composition to react. At this time, the solvent is used to adjust the viscosity or solid content, and the type is not particularly limited as long as the properties of the material constituting the pressure-sensitive adhesive composition are not changed. As the solvent, solvents generally used in the art, such as methyl ethyl ketone, ethyl acetate, and mixtures thereof, may be used. In addition, the solvent may be included in an amount of 30 parts by weight or more, 40 parts by weight or more, 50 parts by weight or more, 60 parts by weight or more, 70 parts by weight or more, or 80 parts by weight or more based on 100 parts by weight of the monomer composition. In another example, the monomer composition It may be included in 200 parts by weight or less, 180 parts by weight or less, 160 parts by weight or less, 150 parts by weight or less, 140 parts by weight or less, 130 parts by weight or less, 120 parts by weight or less, or 110 parts by weight or less compared to 100 parts by weight.

Second acrylic polymer

The pressure-sensitive adhesive composition according to an example of the present application includes (a) a (meth)acrylate unit having a cyclic hydrocarbon side chain, (b) an alkoxy alkylene glycol (meth)acrylate unit, and (c) a (meth)acrylate unit having a polysiloxane side chain. ) a second acrylic polymer comprising an acrylate unit.

The second acrylic polymer of the pressure-sensitive adhesive composition according to an example of the present application may have a weight average molecular weight of 3,000 g/mol or more, 5,000 g/mol or more, 7,000 g/mol or more, or 9,000 g/mol or more, and in another example, 150,000 g/mol or more. g/mol or less, 125,000 g/mol or less, 100,000 g/mol or less, 80,000 g/mol or less, 60,000 g/mol or less, or 40,000 g/mol or less. The weight average molecular weight of the second acrylic polymer may be included within the range formed by the upper and lower limits listed above.

In addition, the second acrylic polymer may have a polydispersity index (PDI) of 1 or more, 1.1 or more, or 1.2 or more, and in other examples, 5 or less, 4 or less, 3 or less, or 2.5 or less. The polydispersity index (PDI) of the second acrylic polymer may be included within the range formed by the upper and lower limits listed above.

In addition, the second acrylic polymer may have a viscosity measured at room temperature of 0.5 cPs or more, 0.75 cPs or more, 1 cPs or more, 1.5 cPs or more, 2 cPs or more, 2.5 cPs or more, or 3 cPs or more. The measured viscosity may be 10 cPs or less, 9.5 cPs or less, 9 cPs or less, 8.5 cPs or less, 8 cPs or less, 7.5 cPs or less, or 7 cPs or less. The viscosity of the second acrylic polymer measured at room temperature may be included within the range formed by the upper and lower limits listed above.

(a) the (meth)acrylate unit having a cyclic hydrocarbon side chain included in the second acrylic polymer can increase the glass transition temperature (Tg) of the pressure-sensitive adhesive composition and improve durability of the cured product. The cyclic hydrocarbon may be at least one selected from the group consisting of a saturated monocyclic hydrocarbon group (cyclic alkyl group) and a bridged hydrocarbon group, which is a hydrocarbon in which two or more rings share one or more pairs of carbon atoms. Here, the bridged hydrocarbon group may have 4 to 30 carbon atoms. Examples of such monomers are cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-methylcyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate (according to IUPAC nomenclature tricyclo[ 5.2.1.0 ^2,6 ]decan-8-yl(meth)acrylate or sometimes called tricyclodecyl (meth)acrylate by other common names), dicyclopentenyl (meth)acrylate (according to IUPAC nomenclature) Sometimes referred to as tricyclo[5.2.1.0 ^2,6 ]decen-8-yl(meth)acrylate), dicyclopentanyloxyethyl (meth)acrylate, isobornyl (meth)acrylate and adamantyl (meth) acrylate or the like, or a mixture of two or more kinds may be mentioned, but is not limited thereto.

(a) the (meth)acrylate unit having a cyclic hydrocarbon side chain included in the second acrylic polymer is 20% by weight or more, 22% by weight or more, 24% by weight or more, 26% by weight or more based on the total weight of the second acrylic polymer Or it may be included in 28% by weight or more, and in other examples, it may be included in 40% by weight or less, 38% by weight or less, 36% by weight or less, 34% by weight or less, or 32% by weight or less based on the total weight of the second acrylic polymer. The content ratio of (a) a (meth)acrylate unit having a cyclic hydrocarbon side chain included in the second acrylic polymer may be included within the range formed by the upper and lower limits listed above.

When the content ratio of (meth)acrylate units having (a) cyclic hydrocarbon side chains in the second acrylic polymer satisfies the above range, the glass transition temperature (Tg) of the pressure-sensitive adhesive composition is increased to improve durability of the cured product. can improve

The (b) alkoxyalkylene glycol (meth)acrylate unit included in the second acrylic polymer is the same as the (ii) alkoxyalkylene glycol (meth)acrylate unit described in the first acrylic polymer. In this regard, the content different from that of the first acrylic polymer will be described.

(b) alkoxy alkylene glycol (meth)acrylate units included in the second acrylic polymer are (a) 80 parts by weight or more, 82.5 parts by weight or more based on 100 parts by weight of (meth)acrylate units having a cyclic hydrocarbon side chain. , 85 parts by weight or more, 87.5 parts by weight or more, 90 parts by weight or more, 92.5 parts by weight or more, 95 parts by weight or more or 97.5 parts by weight or more, in another example (a) having a cyclic hydrocarbon side chain (meta) 120 parts by weight or less, 117.5 parts by weight or less, 115 parts by weight or less, 112.5 parts by weight or less, 110 parts by weight or less, 107.5 parts by weight or less, 105 parts by weight or less, or 102.5 parts by weight or less, based on 100 parts by weight of the acrylate unit. . The content ratio of the (b) alkoxy alkylene glycol (meth)acrylate unit included in the second acrylic polymer may be included within the range formed by the upper and lower limits listed above.

When the content ratio of the (b) alkoxy alkylene glycol (meth)acrylate unit contained in the second acrylic polymer satisfies the above range, the cured product has stable adhesive strength and antistatic performance (ESD characteristics) can be secured.

(c) The (meth)acrylate unit having a polysiloxane side chain included in the second acrylic polymer can ensure excellent compatibility of the pressure-sensitive adhesive composition. The (c) (meth)acrylate unit having a polysiloxane side chain may be derived from a compound represented by Formula 1 below.

[Formula 1]

In Formula 1, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ and R ₇ may each independently be an alkyl group having 1 to 20 carbon atoms or a hydrogen atom. In another example, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ and R ₇ are each independently an alkyl group having 1 to 18 carbon atoms, an alkyl group having 1 to 16 carbon atoms, an alkyl group having 1 to 12 carbon atoms, It may be an alkyl group having 1 to 8 carbon atoms, an alkyl group having 1 to 4 carbon atoms, or a hydrogen atom. The alkyl group is a halogen (chlorine (Cl), iodine (I), bromine (Br), fluorine (F)), an aryl group, a heteroaryl group, an epoxy group, an alkoxy group, a cyano group, a carboxyl group, an acryloyl group, It may be substituted or unsubstituted with one or more selected from the group consisting of a methacryloyl group, an acryloyloxy group, a methacryloyloxy group, a carbonyl group, and a hydroxyl group.

In Formula 1, L may be an alkylene group having 1 to 10 carbon atoms, and in another example, an alkylene group having 1 to 8 carbon atoms, an alkylene group having 1 to 6 carbon atoms, or an alkylene group having 1 to 4 carbon atoms. The alkylene group is a halogen (chlorine (Cl), iodine (I), bromine (Br), fluorine (F)), an aryl group, a heteroaryl group, an epoxy group, an alkoxy group, a cyano group, a carboxyl group, an acryloyl group , It may be substituted or unsubstituted with one or more selected from the group consisting of a methacryloyl group, an acryloyloxy group, a methacryloyloxy group, a carbonyl group, and a hydroxyl group.

In Formula 1, Q is a hydrogen atom or a methyl group.

In addition, n may be an integer in the range of 1 to 20, in other examples, it may be an integer of 2 or more, 3 or more, 4 or more, 5 or more, 6 or more, or 7 or more, and in another example, 18 or less, 16 or less, 14 or less , may be an integer of 12 or less or 10 or less.

The compound represented by Formula 1 may have a molecular weight of 400 g/mol or more, 500 g/mol or more, 600 g/mol or more, 700 g/mol or more, 800 g/mol or more, or 900 g/mol or more. In, the molecular weight of the compound represented by Formula 1 is 5,000 g/mol or less, 4,000 g/mol or less, 3,000 g/mol or less, 2,000 g/mol or less, 1,750 g/mol or less, 1,500 g/mol or less, or 1,250 g/mol or less. It may be mol or less, but is not particularly limited thereto.

(c) the (meth)acrylate unit having a polysiloxane side chain included in the second acrylic polymer, (a) 100 parts by weight or more, 105 parts by weight or more relative to 100 parts by weight of a (meth)acrylate unit having a cyclic hydrocarbon side chain , 110 parts by weight or more, 115 parts by weight or more, 120 parts by weight or more, 125 parts by weight or more or 130 parts by weight or more, and in another example, (a) 100 parts by weight of a (meth)acrylate unit having a cyclic hydrocarbon side chain It may be included in 150 parts by weight or less, 145 parts by weight or less, 140 parts by weight or less, or 135 parts by weight or less per part.

The second acrylic polymer is a monomer comprising (a) a (meth)acrylate having a cyclic hydrocarbon side chain, (b) an alkoxy alkylene glycol (meth)acrylate, and (c) a (meth)acrylate having a polysiloxane side chain. It can be prepared by adding a solvent to the composition to form a mixed composition, and adding an initiator to the mixed composition to react. At this time, the solvent is used to adjust the viscosity or solid content, and the type is not particularly limited as long as the properties of the material constituting the pressure-sensitive adhesive composition are not changed. As the solvent, solvents generally used in the art, such as methyl ethyl ketone, ethyl acetate, and mixtures thereof, may be used. In addition, the solvent may be included in an amount of 75 parts by weight or more, 85 parts by weight or more, 95 parts by weight or more, or 100 parts by weight or more based on 100 parts by weight of the monomer composition, and in another example, 200 parts by weight or less based on 100 parts by weight of the monomer composition, 175 It may be included in parts by weight or less, 150 parts by weight or less, or 125 parts by weight or less.

For the first acrylic polymer and the second acrylic polymer included in the pressure-sensitive adhesive composition according to an example of the present application, necessary monomers are selected from among the above-described monomers, and a mixture of monomers obtained by blending the selected monomers is solution-polymerized. , photo polymerization, bulk polymerization, suspension polymerization, or emulsion polymerization.

The pressure-sensitive adhesive composition according to an example of the present application may include a solvent. The solvent is used to adjust the viscosity or solid content, and the type is not particularly limited as long as the properties of the material constituting the pressure-sensitive adhesive composition are not changed. As the solvent, solvents generally used in the art, such as methyl ethyl ketone, ethyl acetate, and mixtures thereof, may be used.

The pressure-sensitive adhesive composition according to an example of the present application may include a crosslinking agent. As the crosslinking agent, an aliphatic isocyanate crosslinking agent may be used. If such a crosslinking agent implements the configuration and crosslinking structure included in the above-described pressure-sensitive adhesive composition, it is possible to form a pressure-sensitive adhesive layer having appropriate low-speed and high-speed peel strength and required antistatic properties.

The crosslinking agent may be, for example, a crosslinking agent including an aliphatic cyclic isocyanate compound and/or an aliphatic acyclic isocyanate compound. The term aliphatic cyclic isocyanate compound as used herein refers to an isocyanate compound including a cyclic structure, but having a cyclic structure that does not correspond to an aromatic ring, and an aliphatic acyclic isocyanate compound, for example, an aliphatic linear or It may mean a branched isocyanate compound. In the above, the aliphatic cyclic isocyanate compound is, for example, an isocyanate compound such as isophorone diisocyanate, methylene dicyclohexyl diisocyanate, or cyclohexane diisocyanate; A derivative such as a dimer or a trimer or a reaction product of any one of the above and a polyol (ex. trimethylolpropane) may be exemplified, and examples of the aliphatic acyclic isocyanate compound include carbon atoms such as hexamethylene diisocyanate and the like. to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, or 1 to 8 carbon atoms, alkylene diisocyanate compounds, derivatives such as dimers or trimers thereof, or any one of the above and polyol (ex. trimethylol). A reactant with propane) may be exemplified, but is not limited thereto.

In addition, as the crosslinking agent, if necessary, ethylene glycol diglycidyl ether, triglycidyl ether, trimethylolpropane triglycidyl ether, N, N, N', N'-tetraglycidyl ethylenediamine or glycerin epoxy crosslinking agents such as diglycidyl ether; N,N'-toluene-2,4-bis(1-aziridinecarboxamide), N,N'-diphenylmethane-4,4'-bis(1-aziridinecarboxamide), triethylene melamine , an aziridine crosslinking agent such as bisisoprotaloyl-1-(2-methylaziridine) or tri-1-aziridinylphosphine oxide, or aluminum, iron, zinc, tin, titanium, antimony, magnesium and/or vanadium A known crosslinking agent such as a metal chelate crosslinking agent, which is a compound in which a multivalent metal such as acetyl acetone or ethyl acetoacetate is coordinated, may be used together.

The crosslinking agent is present in an amount of 0.1 parts by weight or more, 0.25 parts by weight or more, 0.5 parts by weight or more, 0.75 parts by weight or more, 1 part by weight or more, 1.25 parts by weight or more, 1.5 parts by weight or more, or 2 parts by weight or more based on 100 parts by weight of the first acrylic polymer. In another example, it may be included in 5 parts by weight or less, 4 parts by weight or less, or 3 parts by weight or less based on 100 parts by weight of the first acrylic polymer. The content of the crosslinking agent may be included within the range formed by the upper and lower limits listed above.

When the content of the cross-linking agent satisfies the above range, an appropriate cross-linking structure is implemented, and the low-speed and high-speed peel strength of the pressure-sensitive adhesive may be adjusted to a desired range.

The pressure-sensitive adhesive composition according to an example of the present application may further include an antistatic agent. As the antistatic agent, for example, an ionic compound may be used.

As the ionic compound, for example, a metal salt may be used. The metal salt may include, for example, an alkali metal cation or an alkaline earth metal cation. As the cation, lithium ion (Li ⁺ ), sodium ion (Na ⁺ ), potassium ion (K ⁺ ), rubidium ion (Rb ⁺ ), cesium ion (Cs ⁺ ), beryllium ion (Be ²⁺ ), magnesium ion ( Mg ²⁺ ), calcium ion (Ca ²⁺ ), strontium ion (Sr ²⁺ ), barium ion (Ba ²⁺ ), etc., or more than one kind may be exemplified, and examples include lithium ion, sodium ion, Lithium ions may be used in consideration of one or more kinds of potassium ions, magnesium ions, calcium ions, and barium ions, or ionic stability and mobility.

Anions included in ionic compounds include PF ₆ ^-, AsF ^- , NO ₂ ^- , fluoride (F ^- ), chloride (Cl ^- ), bromide (Br ^- ), iodide (I ^- ), perchlorate (ClO ₄ ^- ), hydroxide (OH ^- ), carbonate (CO ₃ ^2- ), nitrate (NO ₃ ^- ), trifluoromethanesulfonate (CF ₃ SO ₃ ^- ), sulfonate (SO ₄ ^- ), Hexafluorophosphate (PF ₆ ^- ), methylbenzenesulfonate (CH ₃ (C ₆ H ₄ )SO ₃ ^- ), p-toluenesulfonate (CH ₃ C ₆ H ₄ SO ₃ ^- ), tetraborate (B ₄ O ₇ ^2- ), carboxybenzenesulfonate (COOH(C ₆ H ₄ )SO ₃ ^- ), trifluoromethanesulfonate (CF ₃ SO ₂ ^- ), benzonate (C ₆ H ₅ COO ^- ), acetate ( CH ₃ COO ^- ), trifluoroacetate (CF ₃ COO ^- ), tetrafluoroborate (BF ₄ ^- ), tetrabenzylborate (B(C ₆ H ₅ ) ₄ ^- ) or trispentafluoroethyl trifluoro Phosphate (P(C ₂ F ₅ ) ₃ F ₃ ^- ) and the like may be exemplified.

In another example, an anion represented by Formula 2 below or bisfluorosulfonylimide may be used as the anion.

[Formula 2]

[X(YO _a R _f ) _b ] ^-

In Formula 2, X is a nitrogen atom or a carbon atom, Y is a carbon atom or a sulfur atom, R _f is a perfluoroalkyl group, a is 1 or 2, and b is 2 or 3.

In Formula 2, when Y is carbon, m is 1, when Y is sulfur, m is 2, when X is nitrogen, n is 2, and when X is carbon, n may be 3.

The anion or bis(fluorosulfonyl)imide of Formula 2 exhibits high electronegativity due to a perfluoroalkyl group (R _f ) or a fluorine group, and also includes a unique resonance structure, forming a weak bond with a cation At the same time, it has hydrophobicity. Therefore, the ionic compound can impart high antistatic properties even in a small amount while exhibiting excellent compatibility with other components of the composition such as polymers.

R _f in Formula 2 may be a perfluoroalkyl group having 1 to 20 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms. In this case, the perfluoroalkyl group is linear, branched, or It may have a cyclic structure. The anion of Chemical Formula 2 may be a sulfonylmethide-, sulfonylimide-, carbonylmethide-, or carbonylimide-based anion, and specifically, tristrifluoromethanesulfonylmethide, bistrifluoromethanesul Ponylimide, bisperfluorobutanesulfonylimide, bispentafluoroethanesulfonylimide, tristrifluoromethanecarbonylmethide, bisperfluorobutanecarbonylimide or bispentafluoroethanecarbonyl It may be one type or a mixture of two or more types of imide or the like.

As the ionic compound, for example, as a cation, N-ethyl-N,N-dimethyl-N-propylammonium, N,N,N-trimethyl-N-propylammonium, N-methyl-N,N,N -Tributylammonium, N-ethyl-N,N,N-tributylammonium, N-methyl-N,N,N-trihexylammonium, N-ethyl-N,N,N-trihexylammonium, N-methyl Quaternary ammonium such as -N,N,N-trioctylammonium or N-ethyl-N,N,N-trioctylammonium, phosphonium, pyridinium, imidazolium, An organic salt containing pyrolidinium or piperidinium together with the anion component may be used, and if necessary, the metal salt and the organic salt may be used in combination.

The antistatic agent may be included in an amount of 0.05 parts by weight or more, 0.1 parts by weight or more, 0.25 parts by weight or more, or 0.5 parts by weight or more based on 100 parts by weight of the first acrylic polymer, and in another example, 5 parts by weight based on 100 parts by weight of the first acrylic polymer. Or less, 4 parts by weight or less, 3 parts by weight or less, 2 parts by weight or less, or 1 part by weight or less may be included. The content of the antistatic agent may be included within the range formed by the upper and lower limits listed above. The content ratio of the antistatic agent may be changed in consideration of the desired antistatic property or compatibility between components.

The pressure-sensitive adhesive composition according to an example of the present application may further include a silane coupling agent. Examples of the coupling agent include gamma-glycidoxypropyl triethoxy silane, gamma-glycidoxypropyl trimethoxy silane, gamma-glycidoxypropyl methyldiethoxy silane, and gamma-glycidoxypropyl triethoxy silane. , 3-mercaptopropyl trimethoxy silane, vinyltrimethoxysilane, vinyltriethoxy silane, gamma-methacryloxypropyl trimethoxy silane, gamma-methacryloxy propyl triethoxy silane, gamma-aminopropyl tri Methoxy silane, gamma-aminopropyl triethoxy silane, 3-isocyanato propyl triethoxy silane, gamma-acetoacetate propyl trimethoxysilane, gamma-acetoacetate propyl triethoxy silane, beta-cyanoacetyl trimethoxy silane, beta-cyanoacetyl triethoxy silane, and acetoxy aceto trimethoxy silane, and one or a mixture of two or more of the above may be used. For example, it may be appropriate to use a silane coupling agent having an acetoacetate group or a beta-cyanoacetyl group as the silane coupling agent.

The pressure-sensitive adhesive composition according to an example of the present application may further include a tackifier in terms of adjusting adhesive performance. Examples of the tackifier include hydrocarbon-based resins or hydrogenated materials thereof, rosin resins or hydrogenated materials thereof, rosin ester resins or hydrogenated materials thereof, terpene resins or hydrogenated materials thereof, terpene phenol resins or hydrogenated materials thereof, polymerized rosin resins or polymerized rosins. One type or a mixture of two or more types of ester resin or the like can be used.

The pressure-sensitive adhesive composition according to an example of the present application includes a coordination compound capable of forming a coordination bond with the antistatic agent, an initiator, a multifunctional acrylate, an epoxy resin, and an ultraviolet stabilizer within a range that does not affect the effects of the present application. , antioxidants, colorants, reinforcing agents, fillers, antifoaming agents, surfactants (eg, polydimethylsiloxane, etc.) and plasticizers may further include one or more additives selected from the group consisting of.

Protective film, optical element and liquid crystal display device

The pressure-sensitive adhesive sheet according to one example of the present application may be used as, for example, a protective film. The protective film includes a base film and a pressure-sensitive adhesive layer containing a cured product of the pressure-sensitive adhesive composition described above on one side or both sides of the base film.

The protective film may be specifically a protective film for an optical element. For example, it may be used as a protective film for optical elements such as a polarizer, a polarizer, a polarizer protective film, a retardation film, a viewing angle compensation film, and a luminance enhancing film. In this specification, the terms polarizer and polarizer refer to objects that are distinct from each other. That is, a polarizer refers to a film, sheet, or device itself that exhibits a polarizing function, and a polarizer refers to an optical device including other elements together with the polarizer. As other elements that may be included in the optical element together with the polarizer, a polarizer protective film or a retardation layer may be exemplified, but is not limited thereto.

The pressure-sensitive adhesive composition shows a relatively high low-speed peel force and a relatively low high-speed peel force after the cross-linked structure is implemented, has an excellent balance between both peel forces, and has excellent durability reliability, workability, transparency, and antistatic properties. Accordingly, the protective film is used to protect the surface of various optical devices or components, display devices or components, for example, polarizers, retardation plates, optical compensation films, reflective sheets, and luminance enhancement films used in LCDs and other optical elements. However, the use is not limited to the protective film.

The pressure-sensitive adhesive composition shows a relatively high low-speed peel force and a relatively low high-speed peel force after the cross-linked structure is implemented, has an excellent balance between both peel forces, and has excellent durability reliability, workability, transparency, and antistatic properties. Accordingly, the protective film is used to protect the surface of various optical devices or components, display devices or components, for example, polarizers, retardation plates, optical compensation films, reflective sheets, and luminance enhancement films used in LCDs and other optical elements. It can be effectively used as a surface protection film for

A base film included in the protective film according to an example of the present application may be a general film or sheet known in the art. For example, a polyester film such as polyethylene terephthalate or polybutylene terephthalate, a polytetrafluoroethylene film, a polyethylene film, a polypropylene film, a polybutene film, a polybutadiene film, a poly(vinyl chloride) film, or a polyimide film. Plastic films such as Such a film may be composed of a single layer or two or more layers may be laminated, and in some cases may additionally include a functional layer such as an antifouling layer or an antistatic layer. In addition, from the viewpoint of improving adhesion to the substrate, surface treatment such as primer treatment may be performed on one or both surfaces of the substrate.

The thickness of the base film is appropriately selected according to the use and is not particularly limited, and may be typically formed to a thickness of 5 μm to 500 μm or 10 μm to 100 μm.

The thickness of the pressure-sensitive adhesive layer included in the protective film is not particularly limited, and may be, for example, 2 μm to 100 μm or 5 μm to 50 μm.

The method of forming the pressure-sensitive adhesive layer is not particularly limited, and for example, the pressure-sensitive adhesive composition or the coating solution prepared therefrom is applied to a base film or the like and cured by a common means such as a bar coater, or the pressure-sensitive adhesive composition or the coating solution is once releasable. A method of applying to the surface of a substrate, curing, and transferring the material to a substrate film may be used.

Formation of the pressure-sensitive adhesive layer is preferably performed after sufficiently removing components causing bubbles such as volatile components or reaction residues in the pressure-sensitive adhesive composition or the coating solution. Accordingly, the crosslinking density or molecular weight of the pressure-sensitive adhesive is too low, and the elastic modulus is lowered, and air bubbles existing between the glass plate and the pressure-sensitive adhesive layer increase in a high temperature state, thereby preventing the formation of internal scattering bodies.

In addition, the method of curing the pressure-sensitive adhesive composition in the above process is also not particularly limited, and, for example, a suitable aging process is performed so that the polymer and the crosslinking agent included in the composition can react, or the activation of a thermal initiator or a photoinitiator therein is performed. It can be performed through an appropriate high-temperature environment that can be induced (eg, within the range of about 50 ° C to 200 ° C) or light irradiation (eg, ultraviolet irradiation, etc.).

In the protective film according to an example of the present application, the B value according to Equation 1 below for the pressure-sensitive adhesive layer may be 4 or more, 4.5 or more, 5 or more, 5.5 or more, 6 or more, 6.5 or more, 7 or more, 7.5 or more, or 8 or more. In another example, the B value may be 16 or less, 15.75 or less, 15.5 or less, 15.25 or less, 15 or less, 14.75 or less, or 14.5 or less. The value of B may fall within the range formed by the upper and lower limits listed above.

[Equation 1]

B = F _H /F _L

In Equation 1, F _H means a high-speed peel force measured at a peel rate of 30 m/min at a peel angle of 180 °, and F _L is measured at a peel rate of 0.3 m/min at a peel angle of 180 °. Means slow peeling force.

Here, the high-speed peel force and the low-speed peel force may be peel forces measured according to the following physical property measurement method.

The protective film according to an example of the present application may have a high-speed peel force of 80 gf/inch or less, 77.5 gf/inch or less, or 75 gf/inch or less with respect to the pressure-sensitive adhesive layer, and in other examples, 20 gf/inch or more, 25 gf /inch or more, 30 gf/inch or more, 35 gf/inch or more, 40 gf/inch or more, or 45 gf/inch or more. At this time, the high-speed peel force can be measured in the same way as F _H according to Equation 1 above. The high-speed peel force of the pressure-sensitive adhesive layer of the protective film may be included within the range formed by the upper and lower limits listed above. In addition, when the high-speed peel force satisfies the above range, when the protective film is removed from the adherend, it is possible to prevent damage to the adherend and ensure durability capable of protecting the adherend. .

The protective film according to an example of the present application has a low-speed peel force of 1 gf/inch or more, 1.25 gf/inch or more, 1.5 gf/inch or more, 1.75 gf/inch or more, 2 gf/inch or more, 2.25 gf/inch or more with respect to the pressure-sensitive adhesive layer. gf/inch or greater, 2.5 gf/inch or greater, 2.75 gf/inch or greater, 3 gf/inch or greater, 3.25 gf/inch or greater, 3.5 gf/inch or greater, 3.75 gf/inch or greater, 4 gf/inch or greater, or 4.25 gf/inch or greater inch or more, and in other examples, 10 gf / inch or less, 9.75 gf / inch or less, 9.5 gf / inch or less, 9.25 gf / inch or less, 9 gf / inch or less, 8.75 gf / inch or less, 8.5 gf / inch or less, 8.25 gf/inch or less, 8 gf/inch or less, 7.75 gf/inch or less, 7.5 gf/inch or less, 7.25 gf/inch or less, 7 gf/inch or less, 6.75 gf/inch or less, 6.5 gf/inch or less, 6.25 gf /inch or less or 6 gf/inch or less. At this time, the low-speed peel force can be measured in the same way as F _L according to Equation 1 above. With respect to the pressure-sensitive adhesive layer of the protective film, the low-speed peeling force may be included within the range formed by the upper and lower limits listed above. In addition, when the low-speed peeling force satisfies the above range, the protective film attached to the optical element may remain attached without being peeled off in a manufacturing process using the optical element to be described below.

In the protective film according to an example of the present application, an evaluation result according to the following evaluation criteria for a zipping phenomenon may be PASS with respect to the pressure-sensitive adhesive layer. The zipping phenomenon evaluation was evaluated according to the following evaluation criteria for the zipping phenomenon by attaching the protective film to the adherend and peeling it at a peeling speed of 0.5 m/s at a peeling angle of 180° after a certain period of time. Here, the sound generated when OPP (Oriented polypropylene) tape, which is one of the commonly used tapes, is peeled is about 80 dB or more, and the zipping phenomenon was evaluated based on this.

[Jipping phenomenon evaluation criteria]

PASS: When no sound occurs during peeling, or when the average of the decibel values measured through a decibel meter with a measurement interval of 50 mm is less than 80 dB

NG: When the average of decibel values measured by a decibel meter with a measurement interval of 50 mm during peeling is 80 dB or more

The protective film according to an example of the present application has a surface resistance of 1Х10 ⁹ Ω/□ or more, 2.5Х10 ⁹ Ω/□ or more, 5Х10 ⁹ Ω/□ or more, 7.5Х10 ⁹ Ω/□ or more, or 1Х10 ¹⁰ Ω / □ or more, and in another example, the surface resistance may be 1Х10 ¹² Ω / □ or less, 7.5Х10 ¹¹ Ω / □ or less, 5Х10 ¹¹ Ω / □ or less, or 2.5Х10 ¹¹ Ω / □ or less. The surface resistance of the protective film to the pressure-sensitive adhesive layer may be included within the range formed by the upper and lower limits listed above. In addition, when the surface resistance satisfies the above range, adhesion between the base film and the pressure-sensitive adhesive layer may be improved. Surface resistance can be measured according to the method for measuring physical properties below.

The protective film according to an example of the present application may have an absolute value of peeling electrification voltage (ESD) of 3 kV or less, 2 kV or less, 1 kV or less, 0.75 kV or less, 0.5 kV or less, or 0.25 kV or less with respect to the pressure-sensitive adhesive layer. . The absolute value of the peeling electrification voltage with respect to the pressure-sensitive adhesive layer of the protective film may be included within the range formed by the upper limit listed above. The peeling electrification voltage was measured by attaching the protective film to the adherend and then peeling it at a peeling angle of 180° at 30 m/min after a certain period of time. In addition, when the peeling electrification voltage satisfies the above range, static electricity generated in the adherend when the protective film is peeled from the adherend may be prevented.

In the protective film according to an example of the present application, an evaluation result of the pressure-sensitive adhesive layer according to the following moisture permeation contamination evaluation criteria may be PASS. The evaluation of the moisture permeation contamination was evaluated according to the following evaluation criteria for moisture permeation contamination by observing whether static electricity stains were generated on the surface of the adherend after a certain period of time had elapsed after the protective film was attached to the adherend.

[Evaluation Criteria for Moisture Permeation Contamination]

A protective film according to an example of the present application was attached to the triacetyl cellulose (TAC) surface and the polyethylene terephthalate (PET) surface, and distilled water was sufficiently brought into contact with the surface of the protective film, and then sealed with a sealing material. After leaving it for about 20 days, the sealing material was removed, and the surface of the protective film was visually evaluated according to the following criteria to see whether stains were generated through illumination of about 3,000 lux. At this time, the left condition was left at room temperature or left in an environment of 90% relative humidity and 60 °C.

PASS: When left at room temperature and in an environment of 90% relative humidity and 60 ° C., and observed with the naked eye under illumination with a light intensity of 3,000 lux, no stains occur on the surface of the protective film

NG: When left at room temperature or in an environment of 90% relative humidity and 60 ° C., and observed with the naked eye under illumination with a light intensity of 3,000 lux, stains occur on the surface of the protective film.

The protective film according to an example of the present application has a haze of 0.1% or more, 0.2% or more, 0.3% or more, 0.4% or more, 0.5% or more, 0.6% or more, 0.7% or more, 0.8% or more, or 0.9% or more with respect to the pressure-sensitive adhesive layer. % or more, 1% or more, 1.1% or more, 1.2% or more or 1.3% or more. In another example, the haze may be 6% or less, 5.5% or less, 5% or less, 4.5% or less, 4% or less, 3.5% or less, 3% or less, 2.5% or less, or 2% or less. The haze of the pressure-sensitive adhesive layer of the protective film may be included within the range formed by the upper and lower limits listed above. The haze may be measured according to a manual provided through a haze measurement equipment, and may be measured, for example, as described in the method for measuring physical properties below.

In the protective film according to an example of the present application, an evaluation result of the pressure-sensitive adhesive layer according to the following evaluation criteria for coating properties may be PASS. The coating property evaluation was performed by visually observing the reflection of the surface of the adhesive layer by illuminating the surface of the pressure-sensitive adhesive layer with light of about 3000 lux (light observation method), and placing the beam projector and the protective film on a straight line, and white light from the beam projector For the shadow of the protective film appearing on the white surface by releasing, the appearance of the shadow portion corresponding to the surface of the pressure-sensitive adhesive layer was visually observed (beam projector observation method) and evaluated according to the following coating evaluation criteria.

[Criteria for evaluation of coating properties]

PASS: In the light observation method and the beam projector observation method, bubbles or streak-like irregularities were not found on the surface of the adhesive layer of the protective film.

NG: In the light observation method or the beam projector observation method, bubbles or streak-like irregularities were found on the surface of the adhesive layer of the protective film.

The optical element according to an example of the present application may be in a state in which the protective film is attached to a surface. For example, the pressure-sensitive adhesive layer of the protective film is attached to the surface of the optical element, and thus the optical element can be protected by the base film for surface protection.

As the optical element included in the optical element, for example, a polarizer, a polarizing plate, a polarizer protective film, a retardation layer, or a viewing angle compensation layer may be exemplified. As the polarizer in the above, for example, a general type known in the art such as a polyvinyl alcohol polarizer may be employed without limitation.

A polarizer is a functional film or sheet capable of extracting only light vibrating in one direction from incident light vibrating in several directions. Such a polarizer may be, for example, a form in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol-based resin film. The polyvinyl alcohol-based resin constituting the polarizer can be obtained by gelating a polyvinyl acetate-based resin, for example. In this case, the polyvinyl acetate-based resin that can be used may include a homopolymer of vinyl acetate as well as a copolymer of vinyl acetate and other monomers copolymerizable therewith. Examples of the monomer copolymerizable with vinyl acetate include one or a mixture of two or more of unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group. not. The gelation degree of the polyvinyl alcohol-based resin may be usually about 85 mol% to 100 mol%, preferably 98 mol% or more. The polyvinyl alcohol-based resin may be further modified, and for example, polyvinyl formal or polyvinyl acetal modified with aldehydes may also be used. In addition, the polymerization degree of the polyvinyl alcohol-based resin may be about 1,000 to 10,000, preferably about 1,500 to 5,000.

A polyvinyl alcohol-type resin can be formed into a film and it can be used as a raw film of a polarizer. A method for forming a polyvinyl alcohol-based resin into a film is not particularly limited, and a general method known in this field can be used. The thickness of the original film formed of the polyvinyl alcohol-based resin is not particularly limited, and may be appropriately controlled within the range of 1 μm to 150 μm, for example. Considering the ease of stretching, etc., the thickness of the raw film may be controlled to 10 μm or more. The polarizer is a step of stretching (ex. uniaxial stretching) the polyvinyl alcohol-based resin film as described above, a step of dyeing the polyvinyl alcohol-based resin film with a dichroic dye, and adsorbing the dichroic dye, and adsorbing the dichroic dye. It can be manufactured through a process of treating the polyvinyl alcohol-based resin film with an aqueous solution of boric acid and a process of washing with water after treatment with an aqueous solution of boric acid. As the dichroic dye, iodine or a dichroic organic dye may be used.

The polarizing plate may include, for example, the polarizer; And it may include another optical film attached to one side or both sides of the polarizer. Other optical films may include the above-described polarizer protective film, retardation layer, viewing angle compensation layer, and anti-glare layer.

In the above, the polarizer protective film is a protective film for the polarizer as a concept distinct from the protective film including the pressure-sensitive adhesive layer. Examples of the polarizer protective film include cellulose-based films such as triacetyl cellulose; acrylic film; polyester-based films such as polycarbonate films or polyethylene terephthalate films; polyethersulfone-based film; and/or a protective film composed of a polyethylene film, a polypropylene film, a polyolefin film having a cyclo-based or norbornene structure, or a polyolefin-based film such as an ethylene-propylene copolymer, etc. may be formed as a laminated multi-layer film. The thickness of the protective film is also not particularly limited, and may be formed to a conventional thickness.

In the optical device, a surface treatment layer may be present on a surface of the optical device protected by the protective film. The surface treatment layer may have, for example, a surface energy of 30 mN/m or less. That is, in the optical element, a surface treatment layer having a surface energy of 30 mN/m or less is formed on the surface of the optical element protected by the protective film, and the pressure-sensitive adhesive layer of the protective film is attached to the surface treatment layer. can The method for measuring the surface energy is not particularly limited, and a known method for measuring surface energy may be applied. For example, the contact angle of the surface of the optical element may be measured, and the surface energy may be obtained therefrom, or it may be measured using known surface energy measurement equipment.

As the surface treatment layer, a high hardness layer, an anti-glare layer such as an anti-glare (AG) layer or a semi-glare (SG) layer, or a low reflection layer such as an anti-reflection (AR) layer or a low reflection (LR) layer, and the like can be exemplified.

The high hardness layer may be a layer having a pencil hardness of 1H or more or 2H or more under a load of 500 g. Pencil hardness can be measured according to the ASTM D 3363 standard using, for example, a pencil lead specified in KS G2603.

The high hardness layer may be, for example, a high hardness resin layer. The resin layer may include, for example, a room temperature curable, moisture curable, thermal curable or active energy ray curable resin composition in a cured state. In one example, the resin layer may include a thermosetting or active energy ray curable resin composition, or an active energy ray curable resin composition in a cured state. In the description of the high hardness layer, "cured state" may mean a case where the resin composition is converted to a hard state through a crosslinking reaction or polymerization reaction of components included in each of the resin compositions. In addition, in the room temperature curing type, moisture curing type, heat curing type or active energy ray curable resin composition, the curing state can be induced at room temperature or by application of heat or irradiation of active energy rays in the presence of appropriate moisture. composition may mean.

Various resin compositions are known in the art that can satisfy the above-mentioned range of pencil hardness in a cured state, and an average skilled person can easily select a suitable resin composition.

In one example, the resin composition may include an acrylic compound, an epoxy compound, a urethane compound, a phenol compound, or a polyester compound as a main material. Here, "compound" may be a monomer, an oligomer, or a polymer compound.

In one example, as the resin composition, an acrylic resin composition having excellent optical properties such as transparency and resistance to yellowing, for example, an active energy ray-curable acrylic resin composition may be used.

The active energy ray-curable acrylic composition may contain, for example, an active energy ray polymerizable polymer component and a reactive dilution monomer.

The polymer component includes a component known in the industry as an active energy ray polymerizable oligomer such as urethane acrylate, epoxy acrylate, ether acrylate or ester acrylate, or a monomer such as (meth)acrylic acid ester monomer. Polymers of mixtures can be exemplified. As the (meth)acrylic acid ester monomer, alkyl (meth)acrylates, (meth)acrylates having an aromatic group, heterocyclic (meth)acrylates, or alkoxy (meth)acrylates may be exemplified. In this field, various polymer components for producing an active energy ray-curable composition are known, and such compounds may be selected according to need.

Examples of the reactive dilution monomer that may be included in the active energy ray-curable acrylic composition include monomers having one or two or more active energy ray-curable functional groups, such as acryloyl groups or methacryloyl groups. . As the monomer for reactive dilution, for example, the above (meth)acrylic acid ester monomer or multifunctional acrylate may be used.

The selection of the components or the blending ratio of the selected components for preparing the active energy ray-curable acrylic composition are not particularly limited, and may be adjusted in consideration of the hardness and other physical properties of the desired resin layer.

As the anti-glare layer such as the AG layer or the SG layer, for example, a resin layer having a concavo-convex surface or a resin layer containing particles, the particles having a refractive index different from that of the resin layer, may be used. can

As the resin layer above, for example, a resin layer used for forming the high hardness layer can be used. In the case of forming the anti-glare layer, it is not necessary to adjust the components of the resin composition so that the resin layer can exhibit high hardness, but it is okay to form the resin layer so that it can exhibit high hardness.

In the above, the method of forming the concavo-convex surface on the resin layer is not particularly limited. For example, the concave-convex structure can be implemented by curing the resin composition in a state where the coating layer of the resin composition is brought into contact with a mold having a desired concave-convex structure, or by mixing the resin composition with particles having an appropriate particle size, coating, and curing the composition. there is.

The anti-glare layer may also be implemented using particles having a different refractive index from that of the resin layer.

In one example, the particles may have, for example, a difference in refractive index from the resin layer of 0.03 or less or 0.02 to 0.2. If the difference in refractive index is too small, it is difficult to cause haze. Conversely, if the difference is too large, a lot of scattering occurs in the resin layer, increasing the haze, but deterioration of light transmittance or contrast characteristics may be induced. An appropriate particle can be selected taking into account.

The shape of the particles included in the resin layer is not particularly limited, and may be, for example, spherical, elliptical, polyhedral, amorphous, or other shapes. The particles may have an average diameter of 50 nm to 5,000 nm. In one example, as the particle, a particle having irregularities formed on a surface may be used. Such particles have, for example, an average surface roughness (Rz) of 10 nm to 50 nm or 20 nm to 40 nm, and/or a maximum height of irregularities formed on the surface of about 100 nm to 500 nm or 200 nm to 400 nm. nm, and the width of the irregularities may be 400 nm to 1,200 nm or 600 nm to 1,000 nm. These particles are excellent in compatibility with the resin layer and dispersibility within the resin layer.

As the particles, various inorganic or organic particles may be exemplified. Examples of the inorganic particles include silica, amorphous titania, amorphous zirconia, indium oxide, alumina, amorphous zinc oxide, amorphous cerium oxide, barium oxide, calcium carbonate, amorphous barium titanate or barium sulfate, and the like, Examples of the organic particles include particles including cross-linked or non-cross-linked organic materials such as acrylic resin, styrene resin, urethane resin, melamine resin, benzoguanamine resin, epoxy resin, or silicone resin, but are limited thereto. It is not.

The concavo-convex structure formed in the resin layer or the content of the particles is not particularly limited. The shape of the concavo-convex structure or the content of the particles, for example, in the case of the AG layer, the haze of the resin layer is about 5% to 15%, 7% to 13%, or about 10% Adjusted In the case of the SG layer, the haze may be adjusted to be about 1% to 3%. The haze may be measured according to the manufacturer's manual using, for example, a hazemeter such as Sepung's HR-100 or HM-150.

A low reflection layer such as an AR layer or a LR layer may be formed by coating a low refractive index material. Various low-refractive index materials capable of forming the low-reflection layer are known, and all of them may be appropriately selected and used for the optical element. The low reflection layer may be formed to have a reflectance of about 1% or less through a coating of a low refractive index material.

In addition, in the formation of the surface treatment layer, Korean Patent Publication Nos. -0018983, 2003-0068335, 2002-0066505, 2002-0008267, 2001-0111362, 2004-0083916, 2004-0085484, 2008-0005722, 2008-006310 A material known from No. 2008-0101801 or No. 2009-0049557 may also be used.

The surface treatment layer may be formed alone or in combination of two or more. As an example of the combination, a case in which a high hardness layer is first formed on the surface of the substrate layer and then a low reflection layer is formed again on the surface may be exemplified.

A liquid crystal display (LCD) according to an example of the present application may include a liquid crystal panel, and the above-described optical element may be attached to one or both surfaces of the liquid crystal panel.

The type of liquid crystal panel included in the liquid crystal display device is not particularly limited. For example, without being limited thereto, F various passive matrix methods including TN (Twisted Neumatic) type, STN (Super Twisted Neumatic) type, F (ferroelectric) type, and PD (polymer dispersed LCD) type; various active matrix methods including two terminal and three terminal; All known liquid crystal panels including an IPS mode panel and a VA mode panel may be applied. In addition, the types and manufacturing methods of other components included in the liquid crystal display device are not particularly limited, and general configurations in this field can be adopted and used without limitation.

The present application provides a pressure-sensitive adhesive composition capable of forming a pressure-sensitive adhesive layer having antistatic performance while providing appropriate low-speed peel force and high-speed peel force, having an excellent adhesive force balance, suppressing a zipping phenomenon, and preventing adherend contamination. can provide

In addition, the present application may provide a pressure-sensitive adhesive composition, a protective film including a pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive composition, an optical element including the protective film, and a liquid crystal display device including the optical element.

Hereinafter, the present invention will be described through examples and comparative examples, but the scope of the present invention is not limited due to the contents presented below.

<Preparation of materials for pressure-sensitive adhesive composition>

Preparation Example A1

2-ethylhexyl acrylate (2-EHA), butyl acrylate (BA), methoxy polyethylene glycol methacrylate (MPEGMA), 2-hydroxyethyl acrylate (2-hydroxyethyl acrylate, 2-HEA) and 4-hydroxybutyl acrylate (4-hydroxybutyl acrylate, 4-HBA) at 53.5:32.5:9:4:1 (2-EHA:BA:MPEGMA:2-HEA : 4-HBA) was mixed in a weight ratio to prepare a monomer composition. A mixed composition was prepared by mixing about 100 parts by weight of ethyl acetate (EA) with the monomer composition based on 100 parts by weight of the monomer composition.

50% by weight of the prepared mixed composition was put into the reactor, and the remaining 50% by weight was put into a dropping funnel. AIBN (Azobisisobutyronitrile), an initiator, was introduced into the reactor and the dropping funnel, respectively.

The reactor and the dropping funnel were heated to a temperature of 85 ° C to 90 ° C, respectively, and the outlet of the dropping funnel was opened so that the monomer composition therein was dropped into the reactor. At this time, it was adjusted so that it was added dropwise for about 90 minutes to 120 minutes. After all of the mixed composition of the dropping funnel was added dropwise to the reactor, AIBN was added 1 to 3 times in a 1-hour cycle (total amount of AIBN input: about 0.001% to 0.01% based on the total weight of the mixed composition). The reaction was terminated by cooling the temperature of the reactor to room temperature after some time had elapsed when the conversion rate of the solid content was about 99% or more. At this time, the conversion rate of the solid content can be measured using real-time FTIR.

Thereafter, the final solid content was diluted with ethyl acetate (EA) to about 44%, and an antioxidant was added to obtain a weight average molecular weight of about 500,000 g/mol and a viscosity of about 3,000 cPs measured at 23 ° C. , and a first acrylic polymer having a PDI of about 6 was prepared.

Production Example A2

2-ethylhexyl acrylate (2-EHA), butyl acrylate (BA), methoxy polyethylene glycol methacrylate (MPEGMA), 2-hydroxyethyl acrylate (2-HEA) and 4-hydroxybutyl acrylate (4-HBA) was mixed in a weight ratio of 64:30:3:2:1 (2-EHA:BA:MPEGMA:2-HEA:4-HBA) to prepare a monomer composition. A mixed composition was prepared by mixing about 100 parts by weight of ethyl acetate (EA) with the monomer composition based on 100 parts by weight of the monomer composition.

50% by weight of the prepared mixed composition was put into the reactor, and the remaining 50% by weight was put into a dropping funnel. AIBN (azobisisobutyronitrile), an initiator, was introduced into the reactor and the dropping funnel, respectively.

The reactor and the dropping funnel were heated to a temperature of 85 ° C to 90 ° C, respectively, and the outlet of the dropping funnel was opened so that the monomer composition therein was dropped into the reactor. At this time, it was adjusted so that it was added dropwise for about 90 minutes to 120 minutes. After all of the mixed composition of the dropping funnel was added dropwise to the reactor, AIBN was added 1 to 3 times at an interval of 1 hour. The reaction was terminated by cooling the temperature of the reactor to room temperature after some time had elapsed when the conversion rate of the solid content was about 99% or more. At this time, the conversion rate of the solid content can be measured using real-time FTIR.

Thereafter, it was diluted with ethyl acetate (EA) to a final solid content of about 44%, and an antioxidant was added to obtain a weight average molecular weight of about 650,000 g/mol, a viscosity of about 2,400 cPs measured at 23 ° C, and a PDI A first acrylic polymer of about 7 was prepared.

Preparation Example B1

Dicyclopentanyl methacrylate (DCPMA), methoxy polyethylene glycol methacrylate (MPEGMA) and silicone acrylate having a polysiloxane group (supplier: JNC, product name: FM-0711, weight average molecular weight : 1,000 g/mol) in a weight ratio of 30:30:40 (DCPMA:MPEGMA:FM-0711) to prepare a monomer composition. A mixture composition was prepared by mixing about 100 parts by weight of methyl ethyl ketone (MEK) with the monomer composition, based on 100 parts by weight of the monomer composition.

After the prepared mixed composition and AIBN (azobisisobutyronitrile) as an initiator were introduced into the reactor, the reactor was heated to a temperature of 85 ° C to 90 ° C, and AIBN was additionally added 1 to 3 times at a 1-hour cycle. (Total amount of AIBN added: about 0.025% to 0.075% based on the total weight of the mixed composition). When the conversion rate of the solid content was about 99% or more, after some time had elapsed, the temperature of the reactor was cooled to room temperature to terminate the reaction.

Then, it is diluted with ethyl acetate (EA) to a final solid content of about 20%, and the weight average molecular weight is about 30,000 g / mol, the viscosity measured at 23 ° C is about 5 cPs, and the PDI is about 1.5. 2 acrylic polymers were prepared.

Production Example B2

A second acrylic polymer having a weight average molecular weight of about 20,000 g/mol was prepared by preparing in the same manner as in Preparation Example B1, but adjusting the amount of AIBN and additionally adding an antioxidant. The solid content of the second acrylic polymer prepared in Preparation Example B2 except for the weight average molecular weight, and the viscosity and PDI measured at 23 °C were the same as those of the second acrylic polymer of Preparation Example B1.

Comparative Preparation Example B3

Except for preparing a monomer composition by mixing dicyclopentanyl methacrylate (DCPMA) and methoxy polyethylene glycol methacrylate (MPEGMA) in a weight ratio of 30:30 (DCPMA:MPEGMA) If so, it was prepared in the same manner as in Preparation Example B1 to prepare an acrylic polymer having a weight average molecular weight of about 30,000 g/mol.

Comparative Preparation Example B4

30:40 (DCPMA: An acrylic polymer having a weight average molecular weight of about 30,000 g/mol was prepared in the same manner as in Preparation Example B1, except that the monomer composition was prepared by mixing in the weight ratio of MPEGMA:FM-0711).

<Manufacture of pressure-sensitive adhesive composition and pressure-sensitive adhesive layer>

The pressure-sensitive adhesive compositions of each Example and Comparative Example were mixed in a weight ratio as shown in Table 1 below, and methyl ethyl ketone (MEK) was added to prepare a pressure-sensitive adhesive composition such that the final solid content was 33% by weight.

division A1 A2 B1 B2 B3 B4 interface
activator cross-linking agent inorganic salts Example 1 100 - 0.1 - - - 0.05 2.4 0.5 Example 2 100 - 0.3 - - - 0.05 2.4 0.5 Example 3 100 - - 0.1 - - - 2.4 0.5 Example 4 100 - - 0.3 - - - 2.4 0.5 Example 5 100 - - 0.1 - - 0.05 2.4 0.5 Example 6 100 - - 0.3 - - 0.05 2.4 0.5 Example 7 - 100 - 0.1 - - - 2.4 0.5 Example 8 - 100 - 0.3 - - - 2.4 0.5 Example 9 - 100 - 0.5 - - - 2.4 0.5 Comparative Example 1 100 - - - - - - 2.4 0.5 Comparative Example 2 - 100 - - - - - 2.4 0.5 Comparative Example 3 100 - - - - - 0.05 2.4 0.5 Comparative Example 4 - 100 - - - - 0.05 2.4 0.5 Comparative Example 5 100 - - - 0.1 - - 2.4 0.5 Comparative Example 6 - 100 - - 0.1 - - 2.4 0.5 Comparative Example 7 100 - - - - 0.1 - 2.4 0.5 Comparative Example 8 - 100 - - - 0.1 - 2.4 0.5 Comparative Example 9 100 - - - - - - 7.2 0.5

In Table 1, each numerical value represents a part by weight. In addition, SH-8400 of Dow Corning Toray Co., Ltd., a silicone-based surfactant, was used as the surfactant, DR750 (HMDI trimer) of Samyoung Ink Paint Co., Ltd. was used as the crosslinking agent, and lithium bis (trifluoromethylsulfonyl) was used as the inorganic salt. Imide (lithium bis(trifluoromethylsulphonyl)imide, LiTFSI) was used.

Each coating solution was prepared by mixing an appropriate amount of a thermal initiator with the pressure-sensitive adhesive composition prepared in Examples and Comparative Examples.

The coating solution was coated on one side of a biaxially oriented polyethylene terephthalate (PET) film (provider: Kolon/Toray Advanced Materials Co., Ltd.) having a thickness of about 38 μm, and put in an oven at 110 ° C. to cure for about 60 seconds to prepare a protective film (adhesive film) including a uniform pressure-sensitive adhesive layer having a thickness of 15 μm. After that, it was cut into an appropriate size and applied to the following physical property evaluation.

Physical properties presented in Examples and Comparative Examples were evaluated in the following manner.

<How to measure physical properties>

1. Method for measuring adhesive force balance

In accordance with JIS Z 0237, the protective film (adhesive film) prepared in Examples and Comparative Examples was made on the side of triacetyl cellulose (TAC, manufacturer: Hyosung Chemical) and polyethylene terephthalate (PET, manufacturer: TOYOBO), 2 kg It was attached with a roller of, and left for 24 hours under conditions of 23 ° C. temperature and relative humidity of about 35% to 65%. Then, using a tensile tester (manufacturer: Samjitech, product name: SJTA-034SD) that measures the high-speed peel force and a certified tester (manufacturer: Stable Micro Systems, product name: TA.XT plus) that measures the low-speed peel force , Peel force was measured at a peel rate of 30 m/min (high-speed peel force) and 0.3 m/min (low-speed peel force) at a peel angle of 180°, respectively. At this time, the unit of the peel force is gf/inch.

Adhesion balance was measured by the B value according to Equation 1 below.

[Equation 1]

B = F _H /F _L

In Equation 1, F _H means a high-speed peel force measured at a peel speed of 30 m/min at a peel angle of 180 ° according to the peel force measurement method, and F _L is 0.3 m/min at a peel angle of 180 °. It means the low-speed peel force measured at the peel rate of min.

2. Method for evaluating zipping phenomenon

The protective film (adhesive film) prepared in Examples and Comparative Examples was cut into about 210 mm in width and about 300 mm in length (approximately A4 paper size), attached to a glass substrate with a 2 kg roller, and 23 ℃ temperature and 35 It was stored for 24 hours under conditions of relative humidity of % to 65%. Thereafter, using a tensile tester (manufacturer: Samjitech, product name: SJTA-034SD), peeling at a peeling rate of 0.5 m/s at a peeling angle of 90 ° to 180 ° was evaluated according to the following evaluation criteria for the zipping phenomenon. Here, the sound generated when OPP (Oriented polypropylene) tape, which is one of the commonly used tapes, is peeled is about 80 dB or more, and the zipping phenomenon was evaluated based on this.

[Jipping phenomenon evaluation criteria]

PASS: When no sound occurs during peeling, or when the average of the decibel values measured by a decibel meter with a measurement interval of 50 mm is less than 80 dB

NG: When the average of decibel values measured by a decibel meter with a measurement interval of 50 mm during peeling is 80 dB or more

3. Surface resistance measurement method

After leaving the protective films (adhesive films) prepared in Examples and Comparative Examples for 8 hours under conditions of 25 ° C. temperature and 45% to 55% relative humidity (RH), a surface resistance meter (Mitsubishi, model name: MCP-HT800) Antistatic properties were evaluated. At this time, the unit of surface resistance is ohm/square.

4. ESD measurement method

The protective film (adhesive film) prepared in Examples and Comparative Examples was attached to the triacetyl cellulose (TAC, manufacturer: Hyosung Chemical Co.) side and the polyethylene terephthalate (PET, manufacturer: TOYOBO Co.) side with a 2 kg roller, It was left for 24 hours under conditions of a temperature of 23° C. and a relative humidity of 50%. Thereafter, the protective film was cut to a width of about 21 cm and a length of about 30 cm, and a tensile tester (manufacturer: Mirae Engineering, Inc., product name: high-speed peel tester for ESD measurement) was used to measure 30 m/s at a peel angle of 180 °. After peeling at min, the peeling electrification voltage was measured. At this time, the unit of the peeling electrification voltage is kilovolt (kV).

5. How to measure moisture permeability contamination

In accordance with JIS Z 0237, the protective films (adhesive films) prepared in Examples and Comparative Examples were made on the side of triacetyl cellulose (TAC, manufacturer: Hyosung Chemical) and polyethylene terephthalate (PET, manufacturer: TOYOBO), 2 kg It was attached with a roller of, and left for 48 hours under the condition of 23 ℃ temperature and 35% to 65% relative humidity. Thereafter, after the protective film was peeled off, whether stains due to static electricity were observed on the surface of the adherend was evaluated according to the following evaluation criteria for moisture permeation contamination.

[Evaluation Criteria for Moisture Permeation Contamination]

A protective film according to an example of the present application was attached to a polyethylene terephthalate (PET) film as a substrate, and distilled water was sufficiently brought into contact with the surface of the protective film, and then sealed with a sealing material. After leaving it for about 20 days, the sealing material was removed, and the surface of the protective film was visually evaluated according to the following criteria to see whether stains were generated through illumination of about 3,000 lux. At this time, the left condition was left at room temperature or left in an environment of 90% relative humidity and 60 °C.

PASS: When left at room temperature and in an environment of 90% relative humidity and 60 ° C., and observed with the naked eye under illumination with a light intensity of 3,000 lux, no stains occur on the surface of the protective film

NG: When left at room temperature or in an environment of 90% relative humidity and 60 ° C., and observed with the naked eye under illumination with a light intensity of 3,000 lux, stains occur on the surface of the protective film.

6. Measurement method of weight average molecular weight and polydispersity index (PDI)

The number average molecular weight (Mn) and weight average molecular weight (Mw) of all polymers (eg, first acrylic polymer and second acrylic polymer, etc.) that may be included in the pressure-sensitive adhesive composition were measured using GPC (Gel permeation chromatography). . Put the high molecular compound to be analyzed in a 5 mL vial, and dilute in THF (tetrahydro furan) to a concentration of about 1 mg/mL. After that, the standard sample for calibration and the sample to be analyzed were filtered through a syringe filter (pore size: 0.45 ㎛) and then measured. The analysis program used ChemStation from Agilent technologies, and the number average molecular weight (Mn) and weight average molecular weight (Mw) were obtained by comparing the elution time of the sample with the calibration curve. The number average molecular weight (Mn) was obtained as a value (Mw/Mn).

<GPC measurement conditions>

Device: 1200 series by Agilent technologies

Column: Use 2 PLgel mixed B from Polymer laboratories

Solvent: THF

Column temperature: 35 ℃

Sample concentration: 1 mg/mL, 200 μL injection

Standard samples: Polystyrene (Mp: 3900000, 723000, 316500, 52200, 31400, 7200, 3940, 485)

7. Viscosity measurement method

The viscosity of all polymers (for example, the first acrylic polymer and the second acrylic polymer) that may be included in the pressure-sensitive adhesive composition is measured using a viscosity meter (manufacturer: Brookfield, model name: Brookfield LV) and a spindle 63 or 64. was measured. After performing the zero point adjustment of the viscometer, a spindle 63 or 64 was attached to the spindle connection part of the viscometer.

A plate was mounted on the plate connection part of the viscometer, and was adjusted so that a certain gap between the spindle and the plate was formed through a control lever. The plate was separated, and about 0.5 mL of the polymer was applied to the center of the separated plate. The plate coated with the polymer was again mounted on the plate connecting part of the viscometer, and after waiting until the torque value became 0, the measured viscosity was measured at about 25° C. and a rotational speed of 60 rpm.

8. Haze measurement method

For the protective films (adhesive films) prepared in Examples and Comparative Examples, haze was measured according to ISO 13468-1 using a haze meter (manufacturer: Murakami, product name: HR-100).

9. Coatability evaluation method

For the protective film (adhesive film) prepared in Examples and Comparative Examples, the surface of the pressure-sensitive adhesive layer was illuminated with light of about 3000 lux, and the reflection was observed with the naked eye (light observation method). In addition, with respect to the shadow of the protective film appearing on the white surface by placing the beam projector and the protective film on a straight line and emitting white light from the beam projector, the appearance of the shadow portion corresponding to the surface of the adhesive layer was observed with the naked eye. (beam projector observation method). Through the visual observation, evaluation was performed according to the following evaluation criteria for coating property.

[Criteria for evaluation of coating properties]

PASS: In the light observation method and the beam projector observation method, bubbles or streak-like irregularities were not found on the surface of the adhesive layer of the protective film.

NG: In the light observation method or the beam projector observation method, bubbles or streak-shaped irregularities were found on the surface of the adhesive layer of the protective film.

The results of the test data measured in the above Examples and Comparative Examples are summarized in Table 2 below.

division Slow Peel Force (gf/inch) High speed peel force (gf/inch) peel force balance
(B) Zipping phenomenon evaluation surface
Resistance (×10 ¹¹ Ω/□) Stripping charge voltage (ESD, kV) Moisture Permeation Contamination Assessment Haze (%) Coatability evaluation Example 1 4.9 52 10.6 PASS 1.66 -0.14 PASS 1.5 PASS Example 2 4.8 51 10.6 PASS 1.86 -0.1 PASS 1.4 PASS Example 3 4.9 48 9.8 PASS 1.57 -0.24 PASS 1.4 PASS Example 4 5 47 9.4 PASS 1.35 -0.2 PASS 1.5 PASS Example 5 4.4 45 10.2 PASS 1.78 -0.1 PASS 1.4 PASS Example 6 4.3 46 10.7 PASS 1.95 -0.07 PASS 1.4 PASS Example 7 5.8 70 12.1 PASS 4.64 -0.1 PASS 1.4 PASS Example 8 5.5 71 12.9 PASS 4.32 -0.09 PASS 1.4 PASS Example 9 5.7 68 11.9 PASS 4.48 -0.07 PASS 1.4 PASS Comparative Example 1 3.7 92 24.9 PASS 1.42 -0.21 PASS 1.5 PASS Comparative Example 2 4.1 103 25.1 PASS 4.03 -0.26 PASS 1.4 PASS Comparative Example 3 3.2 88 27.5 PASS 1.39 -0.11 PASS 1.5 PASS Comparative Example 4 4.8 100 20.8 PASS 4.32 -0.14 PASS 1.4 PASS Comparative Example 5 3.7 80 21.6 PASS 1.35 -0.12 PASS 1.7 NG Comparative Example 6 4.2 87 20.7 PASS 5.07 -0.16 PASS 1.4 NG Comparative Example 7 3.1 51 16.5 PASS 1.65 -0.07 PASS 1.5 NG Comparative Example 8 3.6 55 15.3 PASS 4.92 -0.09 PASS 1.5 NG Comparative Example 9 5.6 43 7.68 NG 1.56 -0.53 PASS 1.5 PASS

Referring to Table 2, Examples 1 to 9 have low-speed peel force (F _L ) in the range of 4 to 6 gf / inch, high-speed peel force (F _H ) in the range of 45 to 75 gf / inch, peel It can be seen that the force balance (F _H /F _L ) is in the range of 9 to 13. On the other hand, referring to Table 2, Comparative Examples 1 to 4 and 6 exhibited a high-speed peel force (F _H ) of greater than 80 gf/inch, and Comparative Examples 1 to 7 exhibited a peel force balance (F _H /F _L ) is greater than 16.

In addition, referring to Table 2, it can be seen that Examples 1 to 9 all showed PASS in the zipping phenomenon evaluation, moisture permeation stain evaluation, and coating evaluation. On the other hand, referring to Table 2, it can be seen that Comparative Examples 5 to 8 were evaluated as NG in the evaluation of coating property, and Comparative Example 9 was evaluated as NG in the evaluation of the zipping phenomenon.

Claims (20)

comprising a first acrylic polymer and a second acrylic polymer;
The first acrylic polymer includes (i) an alkyl (meth)acrylate unit having a straight-chain or branched-chain alkyl group, (ii) an alkoxy alkylene glycol (meth)acrylate unit, and (iii) a hydroxyalkyl (meth)acrylate contains units;
The second acrylic polymer includes (a) a (meth)acrylate unit having a cyclic hydrocarbon side chain, (b) an alkoxy alkylene glycol (meth)acrylate unit, and (c) a (meth)acrylate unit having a polysiloxane side chain. A pressure-sensitive adhesive composition comprising a. The pressure-sensitive adhesive composition according to claim 1, wherein the first acrylic polymer has a weight average molecular weight of 200,000 g/mol or more or a polydispersity index (PDI, weight average molecular weight/number average molecular weight) in the range of 1.5 to 10. The pressure-sensitive adhesive composition according to claim 1, wherein the second acrylic polymer has a weight average molecular weight of 150,000 g/mol or less. The pressure-sensitive adhesive composition according to claim 1, wherein the first acrylic polymer comprises (i) an alkyl (meth)acrylate unit having a straight-chain or branched-chain alkyl group in an amount of 80 to 97% by weight. The pressure-sensitive adhesive composition of claim 1, wherein the first acrylic polymer comprises (ii) an alkoxy alkylene glycol (meth)acrylate unit in an amount of 1 to 15 parts by weight based on 100 parts by weight of (i) an alkyl (meth)acrylate unit. The pressure-sensitive adhesive composition of claim 1, wherein the first acrylic polymer includes (i) 1 to 10 parts by weight of (iii) hydroxyalkyl (meth)acrylate units based on 100 parts by weight of alkyl (meth)acrylate units. The method of claim 1, wherein the first acrylic polymer is (i) an alkyl (meth)acrylate unit having a straight-chain or branched-chain alkyl group, wherein the straight-chain or branched-chain alkyl group has a first unit having 5 or less carbon atoms, and the carbon number is 6 or more, and the weight ratio (AA2/AA1) of the alkyl (meth)acrylate unit (AA1) having the first unit and the alkyl (meth)acrylate unit (AA2) having the second unit is 1 to the pressure-sensitive adhesive composition within the range of 5. The method of claim 1, wherein the first acrylic polymer is (iii) a hydroxyalkyl (meth)acrylate unit, wherein the hydroxyalkyl includes a third unit having 3 or less carbon atoms and a fourth unit having 4 or more carbon atoms, , The weight ratio (HA4 / HA3) of the hydroxyalkyl (meth) acrylate unit (HA3) having the third unit and the hydroxyalkyl (meth) acrylate unit (HA4) having the fourth unit is 0.01 to 1 Pressure-sensitive adhesive composition within the range. The pressure-sensitive adhesive composition according to claim 1, wherein the second acrylic polymer comprises (a) a (meth)acrylate unit having a cyclic hydrocarbon side chain in an amount of 20 to 40% by weight. The method of claim 1, wherein the second acrylic polymer comprises (a) 80 to 120 parts by weight of (b) alkoxy alkylene glycol (meth)acrylate units based on 100 parts by weight of (meth)acrylate units having cyclic hydrocarbon side chains. A pressure-sensitive adhesive composition. The method of claim 1, wherein the second acrylic polymer comprises (a) 100 to 150 parts by weight of (c) a (meth)acrylate unit having a polysiloxane side chain based on 100 parts by weight of a (meth)acrylate unit having a cyclic hydrocarbon side chain. A pressure-sensitive adhesive composition. The pressure-sensitive adhesive composition according to claim 1, comprising 80 to 99.9% by weight of the first acrylic polymer. The pressure-sensitive adhesive composition according to claim 1, comprising 0.01 to 5 parts by weight of the second acrylic polymer based on 100 parts by weight of the first acrylic polymer. The pressure-sensitive adhesive composition according to claim 1, further comprising an antistatic agent. The pressure-sensitive adhesive composition according to claim 14, comprising 0.05 to 5 parts by weight of the antistatic agent based on 100 parts by weight of the first acrylic polymer. base film; and
A protective film comprising a pressure-sensitive adhesive layer containing a cured product of the pressure-sensitive adhesive composition of claim 1 on one side or both sides of the base film. According to claim 16,
For the pressure-sensitive adhesive layer, a protective film having a B value in the range of 4 to 16 according to the following formula 1:
[Equation 1]
B = F _H /F _L
In Equation 1, F _H means a high-speed peel force measured at a peel rate of 30 m/min at a peel angle of 180 °, and F _L is measured at a peel rate of 0.3 m/min at a peel angle of 180 °. Means slow peeling force. According to claim 16,
For the adhesive layer, F _H is 80 gf / inch or less, or _FL is 1 gf / inch or more protective film. An optical element having the protective film according to claim 16 attached to one or both surfaces. A liquid crystal display device in which the optical element according to claim 19 is attached to one or both surfaces of a liquid crystal panel.