KR20190082514A - Pressure sensitive adhsive composition - Google Patents

Abstract

The present invention relates to an adhesive composition. A protective film comprising the composition is that the balance of low speed peeling force and high speed peeling force is excellent, and antistatic properties are improved. In addition, the composition provides excellent stain resistance and compression resistance to the protective film. The adhesive composition comprises: a block copolymer including a first block and a second block; and a cross-linking agent.

Description

[0001] PRESSURE SENSITIVE ADHSIVE COMPOSITION [0002]

The present application relates to a pressure-sensitive adhesive composition and a protective film containing the pressure-sensitive adhesive composition.

The protective film can be used to prevent foreign matter such as dust from adhering to optical elements such as polarizing plates, household appliances or other plastic parts, or to prevent these surfaces from being damaged. Considering the case where the protective film is removed from the adherend, such a protective film is required to have an appropriate peeling force and antistatic property.

For example, when a protective film is peeled at a high speed for use of a product or for assembling another product, it is required that the peeling force of the protective film (hereinafter, referred to as "high peeling force") be relatively low. On the other hand, the peeling force (hereinafter referred to as " low-speed peeling force ") at the time of peeling at a slow rate must be relatively high so that adequate protection against the peeling agent can be achieved.

In addition, when foreign matter such as dust is sucked mainly by static electricity generated at the time of peeling off the protective film, electrostatic destruction or malfunction of the adhered parts may be caused. Such a static electricity problem becomes more prominent in electronic products in which the accessories are integrated, such as a computer, a liquid crystal TV, or a portable mobile device.

Furthermore, in order to faithfully carry out the function of the protective film for protecting the adherend, it is necessary to exert an excellent resistance against external force or external pressure which can be applied to the adherend while the protective film is attached.

An object of the present invention is to provide a pressure-sensitive adhesive composition for a protective film which is excellent in stain resistance, pressure resistance and anti-static property, and which can provide an appropriate low-speed peeling force and high-speed peeling force.

The above and other objects of the present application can be all solved by the present application, which is described in detail below.

In one example of the present application, the present application relates to a pressure-sensitive adhesive composition. The pressure-sensitive adhesive composition may include a cross-linkable block copolymer and a cross-linking agent. The term " block copolymer " in the present application may refer to a copolymer that is polymerized from mutually different monomers and contains two or more blocks having different glass transition temperatures from each other.

The block copolymer may include a first block having a glass transition temperature of 30 ° C or higher and a second block having a glass transition temperature of -10 ° C or lower. In the present application, the "glass transition temperature of the block" constituting the block copolymer may mean the glass transition temperature calculated according to the method described in the following examples.

In one example, the glass transition temperature of the first block may be at least 30 占 폚, at least 40 占 폚, at least 50 占 폚, at least 60 占 폚, at least 70 占 폚, at least 75 占 폚, or at least 80 占 폚. The upper limit of the first block glass transition temperature is not particularly limited, but may be, for example, 150 ° C or lower, 140 ° C or lower, 130 ° C or lower, 120 ° C or 110 ° C or lower. The first block having a relatively high glass transition temperature can form a hard segment having a relatively rigid property in the block copolymer. The first block may be in the form of glass at room temperature and may impart cohesive force to the pressure sensitive adhesive containing the block copolymer.

In one example, the glass transition temperature of the second block may be below -10 占 폚, below -20 占 폚, below -30 占 폚, or below -35 占 폚. The lower limit of the second block glass transition temperature is not particularly limited, but may be, for example, -80 占 폚 or higher, -70 占 폚 or higher, or -60 占 폚 or higher. The second block having a relatively low glass transition temperature can form a soft segment having a relatively soft characteristic in the block copolymer. The second block may have molecular flow properties at room temperature, and stress relaxation property may be imparted to the pressure sensitive adhesive containing the block copolymer.

The copolymer including both of the first and second blocks satisfying the above-described glass transition temperature range can form a fine phase separation structure in the pressure sensitive adhesive. Since the block copolymer exhibits appropriate cohesive force and stress relaxation property according to a change in temperature, it can be realized excellent physical properties related to a protective film when used in a protective film.

In one example, the block copolymer may be a diblock copolymer or a triblock copolymer comprising a first block and a second block.

In one example, the block copolymer may be a crosslinkable copolymer having a crosslinkable functional group. More specifically, the first block and / or the second block may comprise a polymerization unit derived from a copolymerizable compound having a crosslinkable functional group.

Examples of the crosslinkable functional group include a hydroxyl group, a carboxyl group, an epoxy group, and an isocyanate group. As long as such a crosslinkable functional group can be provided in the first block and / or the second block, the specific kind of the crosslinkable copolymer having a crosslinkable functional group is not particularly limited. For example, hydroxyl group-containing monomers such as hydroxyalkyl (meth) acrylate or hydroxyalkylene glycol (meth) acrylate and the like; (Meth) acryloyloxypropionic acid, 4- (meth) acryloyloxybutyric acid, acrylic acid double, itaconic acid, maleic acid (meth) acrylate, And carboxyl group-containing monomers such as maleic anhydride; May be used singly or in combination of two or more. The crosslinkable copolymer having a crosslinkable functional group can react with a crosslinking agent described below to form a crosslinked structure in the pressure-sensitive adhesive.

The first block may contain an amphoteric ionic functional group. The inclusion of an amphoteric ionic functional group in the first block in the present application means that any compound containing both a cationic functional group and an anionic functional group participates in a polymerization reaction for the formation of the first block so that the cationic functional group and / Or an anionic functional group is introduced into either side chain or main chain of the first block.

In this connection, the first block may contain a polymerization unit derived from a (meth) acrylic acid ester and a polymerization unit derived from a polymerizable compound having an amphoteric functional group. In the present application, the term " polymerization unit " may mean a state in which the above-mentioned predetermined monomer is polymerized in the main chain or side chain of the resin, polymer or polymerization reaction product formed by polymerization of a predetermined monomer as a single impression.

In one example, as the (meth) acrylic acid ester used in forming the first block, for example, alkyl (meth) acrylate may be used. An alkyl (meth) acrylate having an alkyl group of 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms or 1 to 4 carbon atoms may be used in consideration of cohesion, glass transition temperature and tackiness have. The alkyl group may be linear, branched or cyclic. Examples of such monomers include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, (Meth) acrylate, n-butyl (meth) acrylate, sec-butyl (meth) acrylate, pentyl (Meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate and lauryl (meth) acrylate. One or more of these monomers may be used in the first block formation have. Although not particularly limited, it is preferable to use alkyl methacrylate in consideration of the relatively high glass transition temperature of the first block. In this case, it may be advantageous to secure the adhesive force of the protective film to the surface protective substrate through the first block included in the adhesive layer of the protective film.

In one example, the polymerizable compound having an amphoteric ionic functional group may have a carbon-carbon unsaturated double bond. Through the carbon-carbon unsaturated double bond, the polymerizable compound having an amphoteric ionic functional group can be polymerized together with the (meth) acrylic acid ester monomer, so that a first block containing an amphoteric functional group can be provided. For example, the polymerizable compound having an amphoteric ionic functional group may include a (meth) acryloyl group or a vinyl group, and the (meth) acryloyl group may be connected with carbon, oxygen, sulfur, nitrogen or the like . In consideration of a smooth reaction for preparing a block copolymer, it may be more preferable that the polymerizable compound having an amphoteric functional group includes a vinyl group.

The polymerizable compound having an amphoteric ionic functional group may include both a cationic functional group and an anionic functional group.

The kind of the cationic functional group of the polymerizable compound having an amphoteric ionic functional group is not particularly limited. For example, there can be mentioned a pyridinium cation, a piperidinium cation, a pyrrolidinium cation, a cation having a pyrrolene skeleton, a cation having a pyrrole skeleton, an imidazolium cation, a tetrahydropyrimidinium cation, a dihydropyrimidinium cation, A pyrazolium cation, a pyrazolinium cation, a tetraalkylammonium cation, a trialkylsulfonium cation, or a tetraalkylphosphonium cation or the like may be a cationic functional group contained in a polymerizable compound having an amphoteric ionic functional group. The first block may be configured to include one or more of the listed cations.

The kind of the anionic functional group of the polymerizable compound having an amphoteric ionic functional group is not particularly limited. For ^{example, F -, Cl -, Br} -, I -, NO 3 -, (CN) 2 N -, BF 4 -, ClO 4 -, OH -, CO 3 2-, NO 3 -, CF 3 SO _{^{3 -, SO 4-, PF 6}} -, (CF 3) 2 PF 4 -, (CF 3) 3 PF 3 -, (CF 3) 4 PF 2 -, (CF 3) 5 PF -, CH 3 (C ^{_{6 H 4) SO 3 -,}} CF 3 SO 3 -, CF 3 SO 2 -, CF 3 COO -, C 3 F 7 COO -, CF 3 SO 3 -, C 4 F 9 SO 3 -, (CF 3 SO ₃ ) ₂ N ^- , CF ₃ SO ₂ ) ₂ N ^- , RSO ₃ ^- (wherein R is an alkyl group having 1-9 carbon atoms or a phenyl group), RCOO ^{- _{(CF 3) 6 P -,}} (CF 2 CF 2 SO 3 -) 2, (C 2 F 5 SO 2) 2 N -, (CF 3 SO 2) (CF 3 CO) N -, CF 3 CF 2 ( ^{_{CF 3) 2 CO -, (}} CF 3 SO 2) 2 CH -, (SF 5) 3 C -, (CF 3 SO 2) 3 C -, CF 3 (CF 2) 7 SO 3 -, C 6 H 5 _{^{COO -, CH 3 COO -,}} B (C 6 H 5) 4-, or _{P (C 2 F 5) 3} F 3 - and the like may be anionic functional group contained in the polymerizable compound having a functional group zwitterions . The first block may be configured to include one or more of the listed anions.

If it contains the above-mentioned functional groups, i.e., a carbon-carbon unsaturated double bond, a cationic functional group and an anionic functional group, it is preferable that the functional group is directly or indirectly bonded to the amphoteric functional group or the anionic functional group in the polymerizable compound having the amphoteric functional group The kind of the other functional group or element is not particularly limited.

In one example, the polymerizable compound having an amphoteric ionic functional group may be a compound represented by any one of the following general formulas (1) and (2). In the general formulas (1) and (2), X ⁺ is any one of the listed cationic functional groups, and Y ^- is any of the anionic functional groups listed above.

[Chemical Formula 1]

In the above formula (1), R 1 is hydrogen or an alkyl group, and R 2 is an alkylene group or an alkylidene group.

(2)

In Formula 2, R 3 is hydrogen or an alkyl group, A is an aromatic divalent radical, and L is a single bond, an alkylene group or an alkylidene group.

The term alkyl group in the present application means a straight, branched or cyclic alkyl group having 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms or 1 to 4 carbon atoms, unless otherwise specified And the alkyl group may be optionally substituted by one or more substituents.

Unless otherwise specified, the alkylene group or alkylidene group in the present application is a straight, branched or cyclic alkyl group having 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms, ≪ / RTI > or an alkylidene group. The alkylene or alkylidene group may be optionally substituted by one or more substituents.

Examples of the substituent which may optionally be substituted in the alkyl group and the like include an epoxy group such as a halogen such as chlorine or fluorine, a haloalkyl group, a glycidyl group, a glycidyl alkyl group, a glycidoxyalkyl group or an alicyclic epoxy group, An isocyanate group, a thiol group, an alkyl group, an alkoxy group or an aryl group, but the present invention is not limited thereto.

In connection with the above formula (2), an aromatic divalent radical may mean a divalent moiety derived from a compound containing benzene, benzene or any one of the above unless otherwise specified. The benzene-containing compound as described above may mean a compound having two or more benzene rings which are condensed while sharing two carbon atoms or are linked by an appropriate linker. An aromatic divalent radical may comprise, for example, 6 to 25, 6 to 20, 6 to 15 or 6 to 12 carbon atoms. In a preferred example, A in formula (2) may be an arylene group.

Further, in relation to Formula 2, L is a single bond, an alkylene group or an alkylidene group. When L is a single bond, it means that there is no atom at the site. For example, A, an aromatic divalent radical in formula (2), may be directly connected to a cationic functional group or an anionic functional group.

For example, one of the compounds of Formula 1 may be [2- (methacryloyloxy) ethyl] trimethylammonium bis (trifluoromethyl-sulfonyl) imide, One of the compounds may be 3-butyl-1- (4-vinylbenzyl) imidazolium bis (trifluoromethyl-sulfonyl) imide.

As described above, when the amphoteric ionic functional group is directly introduced into the first block, the amphoteric ionic functional groups can be uniformly distributed in the block copolymer, thereby improving the antistatic function.

In one example, if the first block comprises an amphoteric ionic functionality in its block, the second block may be constructed so as not to include such an amphoteric ionic functionality. When a polymerizable compound having an amphoteric ionic functional group having a relatively high glass transition temperature is used in the second block formation, the adhesion property may be inhibited.

In one example, the first block may include 80 to 99.9 parts by weight of polymer units derived from (meth) acrylic acid ester and 0.01 to 20 parts by weight of polymerized units derived from a polymerizable compound having an amphoteric functional group. When the content range is satisfied, appropriate reactivity between the monomers can be ensured and an appropriate glass transition temperature can be given to the first block.

The second block includes a crosslinkable functional group. As the crosslinkable functional group, a hydroxyl group, a carboxyl group, an epoxy group, or an isocyanate group may be used, as described above.

In this regard, the second block may contain a polymerization unit derived from (meth) acrylic acid ester and a polymerization unit derived from a copolymerizable monomer having a crosslinkable functional group.

If the glass transition temperature in the above range can be satisfied, the kind of the (meth) acrylic acid ester monomer that can be used for forming the second block is not particularly limited. For example, the monomers described in the first block may also be used in forming the second block. Considering the glass transition temperature of the second block, alkyl acrylate is preferably used. In this case, it is advantageous that the adhesive layer containing the block copolymer can exhibit a predetermined adhesive property.

In one example, the second block may contain 80 to 99.9 parts by weight of a polymerization unit derived from (meth) acrylic acid ester and 0.1 to 20 parts by weight of a polymerization unit derived from a copolymerizable monomer having a crosslinkable functional group.

The copolymerizable monomer having a crosslinkable functional group may include, for example, a hydroxyl group, a carboxyl group, an epoxy group, or an isocyanate group. When the functional monomer includes the functional group, the type of the specific compound is not particularly limited.

In one example, the copolymerizable monomer having a crosslinkable functional group may be a compound represented by the following general formula (3).

(3)

In Formula 3, R 4 is hydrogen or an alkyl group, Q ₁ and Q ₂ are each independently an alkylene group or an alkylidene group, and n is an integer within a range of 0 to 10. When two or more [-OQ ₂ -] units are present in the general formula (3), the carbon numbers of Q ₂ in each [-OQ ₂ -] unit may be the same or different.

An example of the compound of formula (3) may be hydroxyalkyl acrylate or hydroxyalkylene glycol acrylate. More specifically, it is preferable to use 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (Meth) acrylate, 2-hydroxyethyleneglycol (meth) acrylate or 2-hydroxypropyleneglycol (meth) acrylate are exemplified, but the compounds listed above are not particularly limited.

When such a crosslinkable functional group is included in the second block, an appropriate pressure-sensitive adhesive exhibiting excellent cohesive strength and stress relaxation property in accordance with a change in temperature and excellent in interfacial adhesion and padding resistance can be formed.

In one example, the crosslinkable functional group may be included only in the second block, not included in the first block. When both the first block and the second block include a crosslinkable functional group, hard properties are imparted to both the first block and the second block, so that the tackiness of the pressure-sensitive adhesive may be deteriorated.

In one example, the second block may simultaneously contain a crosslinkable functional group and an aromatic group. In this regard, the second block may further comprise a polymerization unit derived from a copolymerizable monomer having an aromatic group. The copolymerizable monomer having an aromatic group, that is, the compound capable of providing an aromatic group in the second block may be, for example, a compound having an aromatic group and a functional group having a carbon-carbon unsaturated double bond. The functional group having a carbon-carbon unsaturated double bond may be, for example, a vinyl group or a (meth) acryloyl group. At this time, carbon, oxygen, sulfur, nitrogen or the like may be connected to the (meth) acryloyl group.

The type of the copolymerizable monomer having an aromatic group capable of introducing an aromatic group into the second block may be, for example, styrene or a compound corresponding to the following formula (4).

[Chemical Formula 4]

Wherein R5 is hydrogen or an alkyl group, R6 is an alkylene group or an alkylidene group, m is an integer of 0 to 5, L2 is a single bond, an oxygen atom or a sulfur atom, and Ar is an aryl group. With respect to L2, a single bond means a case in which there is no separate atom at a portion connected to L2, and R6 and Ar are directly connected to each other.

The aryl group in relation to the formula (4) means a monovalent residue derived from a compound or a derivative thereof containing a structure in which benzene or two or more benzenes are condensed or bonded. The aryl group may be, for example, an aryl group having 6 to 22 carbon atoms, 6 to 16 carbon atoms, or 6 to 13 carbon atoms, such as a phenyl group, a phenylethyl group, a phenylpropyl group, a benzyl group, , A tolyl group, a xylyl group, a phenylthio group, a naphthyl group or a naphthyloxy group.

Examples of the compound of Formula 4 include phenoxyethyl (meth) acrylate, benzyl (meth) acrylate, 2-phenylthio-1-ethyl (meth) acrylate, 6- (4,6- 2-sec-butylphenoxy) -1-hexyl (meth) acrylate, 2,6-dibromo Dodecylphenyl (meth) acrylate, 2- (1-naphthyloxy) -1-ethyl (meth) acrylate, (Meth) acrylate, 6- (2-naphthyloxy) -1-ethyl (meth) acrylate, 6- (Meth) acrylate, 8- (1-naphthyloxy) -1-octyl (meth) acrylate and 8- (2-naphthyloxy) .

As described above, when the aromatic group is included in the second block, the aromatic group is not included in the first block but may be included only in the second block.

As described above, when the second block includes a crosslinkable functional group and an aromatic group, the second block contains 80 to 95 parts by weight of a polymerization unit derived from a (meth) acrylic acid ester and a polymerization unit derived from a copolymerizable monomer having a crosslinkable functional group 0.5 to 10 parts by weight, and 1 to 15 parts by weight of a polymerization unit derived from a copolymerizable monomer having an aromatic group.

In one example, the block copolymer may comprise an excess of the second block relative to the first block. For example, the block copolymer may include at least 50 parts by weight, at least 60 parts by weight, or at least 70 parts by weight of the second block. More specifically, the block copolymer may include 5 parts by weight to 50 parts by weight of the first block and 50 parts by weight to 95 parts by weight of the second block. If the content range is satisfied, the second block formation reaction succeeding to the formation of the first block may be appropriately performed, thereby providing a pressure sensitive adhesive containing the first block and the second block and having excellent adhesive properties.

The block copolymer satisfying the above structure may have a weight average molecular weight (Mw) in the range of 100,000 to 1,000,000. When the molecular weight is less than the above range, the adhesive property is deteriorated. When the molecular weight exceeds the above range, the adhesive property becomes too strong and it becomes difficult to perform the function as a protective film which is peeled off after use.

In one example, the block copolymer may have a molecular weight distribution (PDI) (Mw / Mn) ranging from 2.0 to 4.5. Specifically, the molecular weight distribution of the block copolymer may be 2.0 or more, 2.5 or more, or 3.0 or more, 4.5 or less, 4.0 or less, or 3.5 or less. When the above range is satisfied, appropriate physical properties required for the adhesive layer for a protective film can be secured.

The method for producing the block copolymer is not particularly limited, and a known method can be used. For example, the block polymer can be polymerized by an LRP (Living Radical Polymerization) method. Specifically, an anionic polymerization method in which an organic rare earth metal complex is used as a polymerization initiator, or an organic alkali metal compound is used as a polymerization initiator in the presence of an inorganic acid salt such as a salt of an alkali metal or an alkaline earth metal, (ATRP) using an atom transfer radical polymerization agent as a polymerization initiator, and an atom transfer radical polymerization agent as a polymerization initiator, in which an electron is introduced (ATRP), Initiators for Continuous Activator Regeneration (ICAR), Atom Transfer Radical Polymerization (ATRP), Inorganic Reducing Agent Reversible A reversible addition-cleavage chain using an addition-cleavage chain transfer agent Polymerization (RAFT), or organic Tel can be used such as a method of using the tellurium compound as an initiator by, a suitable method is selected from among the method may be that the block copolymer produced.

The pressure-sensitive adhesive composition of the present application may contain at least one crosslinking agent capable of reacting with the crosslinkable functional group of the block copolymer to form a chemical crosslinking structure. Non-limiting examples of crosslinking agents include isocyanate crosslinking agents, epoxy crosslinking agents, aziridine crosslinking agents, and metal chelate crosslinking agents.

In one example, when the crosslinkable functional group is a hydroxy group, an isocyanate crosslinking agent may be used. Specifically, an isocyanate crosslinking agent having at least two functional groups capable of reacting with the crosslinkable functional group of the block copolymer may be used. Such isocyanate crosslinking agents include, for example, diisocyanate compounds such as tolylene diisocyanate, xylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isoboron diisocyanate, tetramethylxylene diisocyanate or naphthalene diisocyanate; Or a compound obtained by reacting the diisocyanate compound with a polyol. As the polyol, trimethylolpropane and the like may be used.

In one example, the pressure-sensitive adhesive composition may include 0.01 to 10 parts by weight of a crosslinking agent based on 100 parts by weight of the block copolymer. More specifically, the lower limit of the crosslinking agent content may be 0.1 parts by weight or more, or 1 part by weight or more, and the upper limit may be 10 parts by weight or 5 parts by weight or less. The crosslinking degree of the block copolymer can be appropriately controlled in the range of the content of the crosslinking agent.

The pressure-sensitive adhesive composition of the present application may further comprise an antistatic agent. As the antistatic agent, for example, an ionic compound may be used. As the ionic compound, an organic salt or an inorganic salt can be exemplified.

As the inorganic salt, for example, a metal salt containing a metal ion as a cation may be used. The metal salt may include, for example, an alkali metal cation or an alkaline earth metal cation. Cations, the lithium ions (Li ^+), sodium ion (Na ^+), potassium ion (K ^+), rubidium ions (Rb ^+), cesium ion (Cs ^+), beryllium ion (Be ^{2 +),} magnesium ion ( Mg ^{2 +),} there is a calcium ion (Ca ^2+), strontium ion (a kind or two kinds or more, such as Sr ^{2 +)} and barium ion (Ba ^{+ 2)} can be exemplified.

As the organic salt, for example, an ionic compound containing an organic cation can be used. As the organic cation, an onium cation can be exemplified. The term onium cation as used herein refers to a positive charged ion comprising a structure in which at least some of the charge is localized to atoms such as nitrogen (N), phosphorus (P) and / or sulfur (S) can do. The onium cation may be a cyclic or non-cyclic compound, and when cyclic, it may be an aromatic or non-aromatic compound. The onium cation may further comprise other atoms such as oxygen or carbon atoms in addition to the nitrogen, phosphorus and / or sulfur. The onium cation may optionally be substituted by a substituent such as a halogen, an alkyl group or an aryl group. For example, the acyclic compound may include one or more substituents, which may be cyclic or acyclic substituents, aromatic or nonaromatic substituents.

Examples of the onium cation include N, N-dimethyl N-propylammonium, N, N, N-trimethyl-N-propylammonium, N-methyl- , N-ethyl-N, N, N-tributylammonium, N-methyl-N, N, N-trihexylammonium, , N-trioctylammonium or N-ethyl-N, N, N-trioctylammonium and the like, phosphonium, pyrolidinium) or piperidinium, and the like.

Examples of anions included in the ionic compounds such as inorganic salts and organic salts include PF ₆ ^- , AsF ^- , NO 2 ^- , fluoride (F ^- ), chloride (Cl ^- ), bromide (Br ^- ), iodide ^- ), perchlorate (ClO ₄ ^- ), hydroxide (OH ^- ), carbonate (CO ₃ ^2- ), nitrate (NO ₃ ^- ), trifluoromethanesulfonate (CF ₃ SO ₃ ^- (SO ₄ ^-), phosphate (PF ₆ ^-) hexafluoropropane, methyl benzene sulfonate _{(CH 3 (C 6 H 4} ) SO 3 -), p- toluenesulfonate _{(CH 3 C 6 H 4 SO} 3 -) , tetraborate ^{_{(B 4 O 7 2 -)}} , carboxymethyl sulfonate _{(COOH (C 6 H 4)} SO 3 -), sulfonate to flow (CF ₃ SO ₂ ^-), benzo carbonate (C ₆ H ₅ COO ^-), acetate (CH ₃ COO ^-), a triple acetate (CF ₃ COO ^-), borates (BF ₄ ^{tetrafluoro-),} tetra-benzyl borate _{(B (C 6 H 5)} 4 -) or tris-pentafluoropropane (P (C ₂ F ₅ ) ₃ F ₃ ^- ) and the like can be exemplified have.

In another example, the anion may be an anion or bifluorosulfonylimide represented by the following formula (5), or the like.

[Chemical Formula 5]

[D (GO _m R _f ) _n ] ^-

D is a nitrogen atom or a carbon atom, G is a carbon atom or a sulfur atom, R _f is a perfluoroalkyl group, m is 1 or 2, and n is 2 or 3.

In Formula 5, m is 1 when G is carbon, m is 2 when G is sulfur, n is 2 when D is nitrogen, and n can be 3 when D is carbon.

The anion or bis (fluorosulfonyl) imide of formula (5) exhibits high electronegativity due to the perfluoroalkyl group (R _f ) or the fluorine group, and also includes a unique resonance structure to form a weak bond with the cation And at the same time has hydrophobicity. Therefore, the ionic compound exhibits excellent compatibility with other components of the composition such as a polymer, and can give a high antistatic property even in a small amount.

R _f in formula (5) 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, wherein the perfluoroalkyl group may be linear, branched or cyclic Structure. The anion of formula (5) may be a sulfonylimide-based, sulfonylimide-based, carbonylimide-based or carbonylimide-based anion, and specifically includes tris trifluoromethanesulfonylmethide, bistrifluoromethanesulfonyl A perfluorobutanesulfonylimide, bispentafluoroethanesulfonylimide, tris trifluoromethanecarbonylmide, bis perfluorobutanecarbonylimide or bispentafluoroethanecarbonyl, bispentafluoroethanesulfonylimide, bis Imide, etc., or a mixture of two or more species.

The ratio of the antistatic agent can be adjusted in consideration of the desired antistatic property and the like. In one example, the composition may be included in the range of 0.1 to 10 parts by weight, relative to 100 parts by weight of the block copolymer. Specifically, the upper limit of the antistatic agent content may be 5 parts by weight or less, 3 parts by weight or less, and 1 part by weight or less, based on 100 parts by weight of the block copolymer.

The pressure-sensitive adhesive composition may further include an additive such as an epoxy resin, a curing agent, a UV stabilizer, an antioxidant, a colorant, a reinforcing agent, a filler, a defoamer, a surfactant or a plasticizer. The specific kind or content of the additive is not particularly limited.

In one example of this application, the present application is directed to a pressure sensitive adhesive sheet. The adhesive sheet may be, for example, a protective film, specifically a protective film for an optical element.

The pressure-sensitive adhesive sheet can be used as a protective film for an optical element such as a polarizing plate, a polarizer, a retardation film, a viewing angle compensating film, and a luminance improving film. In the present application, the term polarizer and polarizer plate refer to objects that are distinguished from each other. That is, the polarizer refers to a film, sheet or device itself exhibiting a polarization function, and the polarizer refers to an optical element including other elements together with the polarizer. Other elements that can be included in the optical element together with the polarizer include, but are not limited to, a polarizer protective film or a retardation layer.

The pressure-sensitive adhesive sheet may include, for example, a surface protecting base film and a pressure-sensitive adhesive layer present on one side of the base film. The pressure-sensitive adhesive layer may include, for example, a pressure-sensitive adhesive composition that is crosslinked, that is, a pressure-sensitive adhesive composition having a crosslinked structure, as the pressure-sensitive adhesive composition.

The pressure-sensitive adhesive composition exhibits a relatively high low-rate peel force and a relatively low high-rate peel-off force after the crosslinked structure is implemented, and is excellent in the balance of the peel force and is excellent in endurance reliability, workability, transparency, Excellent. Thus, the protective film is used for protecting the surface of an optical element such as a polarizing plate, a retardation plate, an optical compensation film, a reflection sheet and a brightness enhancement film used for various optical devices or parts, display devices or parts such as LCD Can be effectively used as a surface-protective film for a light-emitting device.

As the surface protective base film, a general film or sheet known in this field can be used. 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 And the like. Such a film may be composed of a single layer, or two or more layers may be laminated, and in some cases, a functional layer such as an antifouling layer or an antistatic layer may further be included. From the viewpoint of improving the adhesion of the substrate, a surface treatment such as a primer treatment may be performed on one surface or both surfaces of the substrate.

The thickness of the base film may be suitably selected depending on the application and is not particularly limited, and may be generally formed to a thickness of 5 to 500 탆 or 10 to 100 탆.

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

The method for forming the pressure-sensitive adhesive layer is not particularly limited, and for example, a method in which a pressure-sensitive adhesive composition or a coating solution prepared therefrom is applied to a base film or the like by a conventional means such as a bar coater and then cured can be used. Alternatively, the pressure-sensitive adhesive layer can be formed by applying the pressure-sensitive adhesive composition or coating liquid to the surface of the peelable base material once, curing it, and transferring it to the base film again.

The process of forming the pressure-sensitive adhesive layer is preferably performed after sufficiently removing the bubble-inducing component such as the volatile component or the reaction residue in the pressure-sensitive adhesive composition or the coating liquid. Accordingly, the crosslinking density or the molecular weight of the pressure-sensitive adhesive is too low to lower the elastic modulus, and bubbles existing between the glass plate and the pressure-sensitive adhesive layer at high temperature are increased to form scattering bodies therein.

Also, the method of curing the pressure-sensitive adhesive composition in the above process is not particularly limited. For example, the polymer and the crosslinking agent contained in the composition may be subjected to an appropriate aging process to react them, or the activation of a photoinitiator For example, ultraviolet irradiation or the like.

The pressure-sensitive adhesive layer may have, for example, a gel content of about 80% to about 99%. The gel content can be calculated, for example, by the following equation (1).

[Equation 1]

Gel content = B / A x 100

In the formula 1, A represents the mass of the pressure-sensitive adhesive, and B represents the dry mass of the insoluble fractions recovered after immersing the pressure-sensitive adhesive in ethyl acetate at room temperature for 48 hours.

The protective film of the present application having the above configuration can have an appropriate peeling force. For example, according to one example of the present application, when a protective film is attached to a glass substrate via a pressure-sensitive adhesive layer and a low peel strength is peeled at a 180 degree angle and at a rate of 0.3 m / min is 7 RTI ID = 0.0 > g / inch. ≪ / RTI > According to an embodiment of the present application, a high peel strength in the case of peeling at 180 degrees and at a rate of 30 m / min after attaching a protective film to a glass substrate via a pressure-sensitive adhesive layer is 70 to 85 gf / inch < / RTI > may be provided. As described above, in the case of having a suitably high low vulcanizing force and a suitably low high releasing force, the function as the surface protective film can be faithfully performed. In one example, the high peel strength / low peel strength ratio (H / L) to the low peel strength may be 9 to 10.

The present application can provide a pressure-sensitive adhesive composition for a surface protective film having an excellent balance of low-speed peeling force and high-speed peeling force and having improved antistatic properties. In addition, the protective film comprising the pressure-sensitive adhesive layer formed from the composition produced according to one example of the present application has excellent durability as well as resistance to stain.

Hereinafter, the present application will be described in detail by way of examples. However, the scope of protection of the present application is not limited by the embodiments described below.

<Measurement method>

Molecular Weight

The number average molecular weight (Mn), the weight average molecular weight (Mw) and the molecular weight distribution (Mw / Mn) were measured by GPC (gel permeation chromatography) under the following conditions. For the calibration curve, the measurement results using standard polystyrene of the Agilent system were converted.

<Measurement Conditions>

Measuring instrument: Agilent GPC (Agilent 1200 series, U.S.)

Column: Two PL Mixed B connections

Column temperature: 40 ° C

Eluent: THF (tetrahydrofuran)

Flow rate: 1.0 mL / min

Concentration: ~ 1 mg / mL (100 μL injection)

Glass transition temperature

The glass transition temperature (T _g ) of each block forming the block copolymer or block copolymer was calculated according to the following equation.

<Formula>

1 / Tg =? Wn / Tn

In the above formula, Wn is the weight fraction of the block copolymer or the monomer applied to each block of the copolymer, and Tn is the glass transition temperature when each monomer forms a homopolymer. That is, in the formula (A), the value obtained by dividing the weight fraction of the used monomers by the glass transition temperature (Wn / Tn) obtained when the monomers are formed into the homopolymer is calculated for each monomer to be.

Peel force

Low peeling force : The pressure-sensitive adhesive sheet produced in Examples and Comparative Examples was coated on the anti-glare layer (trade name: ARI, LG Chemical) of a polarizing plate on which an anti-glare layer was formed according to JIS Z 0237 Respectively. Thereafter, the sample was stored at a temperature of 23 ° C and a relative humidity of 65% for 24 hours, and then cut to a length of 25 mm and a length of 120 mm. Thereafter, the specimen was fixed on a glass substrate, and the peeling force was measured while peeling the adhesive sheet in the transverse direction from the antiglare layer using a tensile tester (Texture analyzer, model name: TA XT Plus). The peeling angle was 180 占 and the peeling speed was 0.3 m / min. The peel force was measured for two identical specimens and the mean value was used.

High-speed peeling force : A specimen cut to a length of 25 mm and a length of 250 mm, and a peel-off adhesive sheet at a peeling speed of 30 m / min, The peel force was measured.

Peeling Voltage (ESD)

Protective films, that is, the polarizing plates with the pressure-sensitive adhesive sheets prepared in Examples and Comparative Examples were cut to a size of about 220 mm and about 250 mm, and specimens were prepared. Respectively. The polarizing plate was attached to the glass plate under constant temperature / humidity conditions, and then the peeling electrification voltage was measured with a tensile tester at a peeling angle of about 180 DEG and a peeling rate of 40 m / min. The peeling electrification voltage was measured using a electrostatic potential meter, KSD-200, at a distance of 4 cm from the sheet upon peeling. The peeling electromotive force was measured for two identical specimens and the mean value was used.

Contamination  evaluation

The pressure-sensitive adhesive sheets prepared in Examples and Comparative Examples were cut so as to have a length of 150 mm and a length of 250 mm. On the anti-glare film (trade name: ARI, LG Chemical) Respectively. Thereafter, a black adhesive film was adhered to the surface of the anti-glare film on which the adhesive sheet was not adhered, and was stored at room temperature for 24 hours. Subsequently, the pressure-sensitive adhesive sheet was peeled off and left for 1 hour at a temperature of 60 ° C and a relative humidity of 90%. Then, a Xenon HID lamp (Polarion) was irradiated to visually confirm the presence or absence of contaminants formed on the anti- .

<Evaluation Criteria>

A: If no contaminants are observed

B: Contamination is observed.

Impact resistance (Steel ball drop test)

The pressure sensitive adhesive sheet prepared in Examples and Comparative Examples was cut to a size of 5 cm x 5 cm and the sample was placed on a Texture Analyzer (model name: TA XT Plus). Then, The pressing force of the protective film was measured when the test piece was pressed at a load of 10 g / min under the conditions of 1000 gf, 1500 gf, and 2000 gf. At this time, the pressing time was 30 seconds. The protective film was observed with the naked eye and an optical microscope, and the puncture resistance was evaluated according to the following criteria. In the case where the pressure resistance is excellent, the pressure is restored immediately after the pressure is lower than a certain level, leaving no trace, and cracks may be generated in the pressure-sensitive adhesive layer at a certain force.

<Evaluation Criteria>

O: No pressing

△: restored after 1 hour of pressing

X: Not restored (destroyed) after 1 hour of pressing.

&Lt; Copolymer Manufacturing example >

Manufacturing example  1: Preparation of block copolymer (A)

0.32 g of EBiB (ethyl 2-bromoisobutyrate), 97.24 g of methyl methacrylate (MMA: methyl methacrylate), 18.32 g of butyl methacrylate (BMA: butyl methacrylate) 6.11 g of zolium bistrifluoromethylsulfonylimide (VBIC-Tf2N) were mixed in 47.1 g of ethyl acetate (EAc). The flask containing the mixture was sealed with a rubber bum, nitrogen purged and stirred at about 25 ° C for about 30 minutes, and dissolved oxygen was removed through bubbling. Thereafter, 0.02 g of CuBr ₂ , 0.05 g of TPMA (tris (2-pyridylmethyl) amine) and 0.13 g of V-65 (2,2'-azobis (2,4-dimethyl valeronitrile) And the reaction was started by immersing in a reaction tank at about 67 ° C (polymerization of the first polymer block). 607.9 g of butyl acrylate (BA) previously bubbled with nitrogen, 69.1 g of phenoxyethylacrylate (PEA), 69.1 g of hydroxybutyl acrylate (HBA), and 10.0 g of methyl methacrylate 13.8 g, and ethyl acetate (EAc) (363.3 g) was added in the presence of nitrogen. Then, 0.02 g of CuBr2, 0.05 g of TPMA and 0.2 g of V-65 were added to the reaction flask, and a chain extension reaction was carried out (polymerization of the second polymer block). When the conversion of the acrylic acid ester monomer reached 80% or more, the reaction mixture was exposed to oxygen and diluted with an appropriate solvent to terminate the reaction, thereby preparing a block copolymer having the structure shown in Table 1 below (V- 65 was appropriately divided and added until the end of reaction in consideration of half-life).

Manufacturing example  2 to 5: Preparation of block copolymers A2 to A5

A block copolymer was prepared in the same manner as in Production Example 1, except that the kind was adjusted as shown in Table 1 below.

[Table 1]

Manufacturing example  6: Preparation of random copolymer B1

To a 1 L reactor equipped with a cooling device for regulating the temperature of the reflux of nitrogen gas, 98.1 parts by weight of 2-ethylhexyl acrylate, 1.9 parts by weight of 4-hydroxybutyl acrylate And n-dodecyl mercaptan as a molecular weight regulator was added in an amount of 300 ppm, and then 150 parts by weight of ethyl acetate was added as a solvent. Next, nitrogen gas was purged for about 60 minutes to remove oxygen, and 0.03 part by weight of V-59 (2,2'-azobis (2-methylbutyronitrile)), which is a reaction initiator, was added while keeping the temperature at 60 ° C. And reacted for 6.5 hours to prepare a random copolymer having the structure shown in Table 2 below. The weight average molecular weight (Mw) of the prepared random copolymer (B1) was about 380,000 and the molecular weight distribution (PDI) was about 6.7.

Manufacturing example  7: Preparation of random copolymer B2

To a 1 L reactor equipped with a cooling device for regulating the temperature of the refluxed nitrogen gas, 93.1 parts by weight of 2-ethylhexyl acrylate, 1.9 parts by weight of 4-hydroxybutyl acrylate , 5 parts by weight of 3-butyl-1- (4-vinylbenzyl) imidazolium bistrifluoromethylsulfonylimide (VBIC-Tf2N) was added, and 300 parts by weight of n-dodecylmercaptan And 150 parts by weight of ethyl acetate was added as a solvent. Next, nitrogen gas was purged for about 60 minutes to remove oxygen, and 0.03 part by weight of V-59 (2,2'-azobis (2-methylbutyronitrile)), which is a reaction initiator, was added while keeping the temperature at 60 ° C. And reacted for 6.5 hours to prepare a random copolymer having the structure shown in Table 2 below. The weight average molecular weight (Mw) of the prepared random copolymer (B1) was about 400,000 and the molecular weight distribution (PDI) was about 7.3.

[Table 2]

Example  And Comparative Example

Example  One.

Preparation of pressure-sensitive adhesive composition: 4.5 parts by weight of a multifunctional crosslinking agent (Coronate L, manufactured by NPU, Japan) and 100 parts by weight of an antistatic ionic compound lithium bistrifluoromethanesulfonyl 0.5 parts by weight of imide (LiTFSI) were uniformly blended and diluted to a proper concentration in consideration of coating properties. The content of each component is shown in Table 3.

Production of pressure-sensitive adhesive sheet (protective film) The pressure-sensitive adhesive composition thus prepared was coated on one side of a PET (poly (ethylene terephthalate)) film (thickness: 38 μm) and dried to form a uniform coating layer (adhesive layer) having a thickness of about 20 μm. Subsequently, the adhesive layer was maintained at about 90 DEG C for about 3 minutes to induce a crosslinking reaction on the coating layer to produce a pressure-sensitive adhesive sheet. Table 4 shows the measurement results of the sheet-related properties.

Example  2 to 4 and Comparative Example  1 to 3

A pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet were prepared in the same manner as in Example 1, except that components and ratios thereof were adjusted differently as shown in Table 3 below.

[Table 3]

[Table 4]

As can be seen from the above table, in the case of the protective film of Example of the present invention including the block copolymer according to one example of the present application, it can be confirmed that the film has an appropriate low-speed peeling force and a high-speed peeling force and a low peeling electrification voltage. In addition, the present application can provide a protective film capable of suppressing the generation of scratches and cracks in the adherend to be protected, and preventing contamination of the adherend from a substance derived from the additive, because the adherend is strongly pressed against a predetermined external force .

Claims (20)

A first block having a glass transition temperature of 30 DEG C or higher and containing an amphoteric ionic functional group; And a second block having a glass transition temperature of -10 占 폚 or lower and comprising a crosslinkable functional group; And
A crosslinking agent;
&Lt; / RTI &gt; The pressure-sensitive adhesive composition according to claim 1, wherein the first block comprises a polymerization unit derived from a (meth) acrylic acid ester and a polymerization unit derived from a polymerizable compound having an amphoteric ionic functional group. The pressure-sensitive adhesive composition according to claim 2, wherein the polymerizable compound having an amphoteric ionic functional group has a carbon-carbon unsaturated double bond. The pressure-sensitive adhesive composition according to claim 3, wherein the polymerizable compound having an amphoteric ionic functional group includes both a cationic functional group and an anionic functional group. The polymerizable composition according to claim 4, wherein the polymerizable compound having an amphoteric functional group is at least one selected from the group consisting of a pyridinium cation, a piperidinium cation, a pyrrolidinium cation, a pyrroline skeleton having a pyrrole skeleton, an imidazolium cation, A pressure-sensitive adhesive composition comprising a hydropyrimidinium cation, a dihydropyrimidinium cation, a pyrazolium cation, a pyrazolinium cation, a tetraalkylammonium cation, a trialkylsulfonium cation, or a tetraalkylphosphonium cation as a cationic functional group. The method of claim 5, wherein the polymerizable compound having the amphoteric ion functional groups are ^{F -, Cl -, Br -} , I -, NO 3 -, (CN) 2 N -, BF 4 -, ClO 4 -, OH - _{^{, CO 3 2-, NO 3 -}} , CF 3 SO 3 -, SO 4-, PF 6 -, (CF 3) 2 PF 4 -, (CF 3) 3 PF 3 -, (CF 3) 4 PF 2 - ^{_{, (CF 3) 5 PF -}} , CH 3 (C 6 H 4) SO 3 -, CF 3 SO 3 -, CF 3 SO 2 -, CF 3 COO -, C 3 F 7 COO -, CF 3 SO 3 - ^{_{, C 4 F 9 SO 3 -}} , (CF 3 SO 3) 2 N -, CF 3 SO 2) 2 N -, RSO 3 - ( where, R is an alkyl group having a carbon number of 1-9 or a phenyl group), RCOO ^- (where , R is an alkyl group or a phenyl group having a carbon number of _{1-9), (CF 3) 6} P -, (CF 2 CF 2 SO 3 -) 2, (C 2 F 5 SO 2) 2 N -, (CF 3 SO 2) ^{_{(CF 3 CO) N -,}} CF 3 CF 2 (CF 3) 2 CO -, (CF 3 SO 2) 2 CH -, (SF 5) 3 C -, (CF 3 SO 2) 3 C -, CF 3 ^{_{(CF 2) 7 SO 3 -}} , C 6 H 5 COO -, CH 3 COO -, B (C 6 H 5) 4-, or _{P (C 2 F 5) 3} F 3 - a containing an anionic functional group Sensitive adhesive composition. The pressure-sensitive adhesive composition according to claim 6, wherein the polymerizable compound having an amphoteric ionic functional group is a compound represented by any one of the following formulas (1) and (2)
[Chemical Formula 1]

In the above formula (1), R 1 is hydrogen or an alkyl group, R 2 is an alkylene group or an alkylidene group, X ⁺ is a cationic functional group, and Y ^- is an anionic functional group.
(2)

In Formula 2, R3 is hydrogen or an alkyl group, A is an aromatic divalent radical, L is a single bond or an alkylene group or an alkylidene group, X ⁺ is a cationic functional group, Y ^- is an anionic functional group. The method of claim 3, wherein the first block comprises 80 to 99.9 parts by weight of a polymerization unit derived from (meth) acrylic acid ester; And 0.01 to 20 parts by weight of polymerized units derived from a polymerizable compound having an amphoteric ionic functional group. The pressure-sensitive adhesive composition according to claim 1, wherein the second block comprises 80 to 99.9 parts by weight of a polymerization unit derived from (meth) acrylic acid ester and 0.01 to 20 parts by weight of a polymerization unit derived from a copolymerizable monomer having a crosslinkable functional group. The pressure-sensitive adhesive composition according to claim 1, wherein the crosslinkable functional group is a hydroxyl group, a carboxyl group, an epoxy group, or an isocyanate group. The pressure-sensitive adhesive composition according to claim 1, wherein the second block further comprises an aromatic group. 12. The composition according to claim 11, wherein the second block is a copolymer comprising 80 to 95 parts by weight of a polymerization unit derived from (meth) acrylic acid ester, 0.5 to 10 parts by weight of a polymerization unit derived from a copolymerizable monomer having a crosslinkable functional group, And 1 to 15 parts by weight of a polymerization unit derived from the monomer (A). 13. The pressure-sensitive adhesive composition according to claim 12, wherein the copolymerizable monomer having an aromatic group is styrene or a pressure-
[Chemical Formula 4]

Wherein R5 is hydrogen or an alkyl group, R6 is an alkylene group or an alkylidene group, m is an integer of 0 to 5, L2 is a single bond, an oxygen atom or a sulfur atom, and Ar is an aryl group. The pressure-sensitive adhesive composition according to claim 1, wherein the block copolymer comprises 5 parts by weight to 40 parts by weight of the first block and 60 parts by weight to 95 parts by weight of the second block. The pressure-sensitive adhesive composition according to claim 1, wherein the block copolymer has a weight average molecular weight (Mw) in the range of 100,000 to 1,000,000. The pressure-sensitive adhesive composition according to claim 15, wherein the block copolymer has a molecular weight distribution (Mw / Mn) in the range of 2.0 to 4.0. The pressure-sensitive adhesive composition according to claim 1, wherein the block copolymer is a diblock copolymer or a triblock copolymer. The pressure-sensitive adhesive composition according to claim 1, which comprises 0.01 to 10 parts by weight of a crosslinking agent based on 100 parts by weight of the block copolymer. The pressure-sensitive adhesive composition according to claim 1, further comprising 0.01 to 10 parts by weight of an antistatic agent relative to 100 parts by weight of the block copolymer. A surface protective base film; And a pressure-sensitive adhesive layer formed on one surface of the surface-protecting base film and comprising the pressure-sensitive adhesive composition according to any one of claims 1 to 16 crosslinked.