KR20190079430A - Adhesive composition and protection film using the same - Google Patents

Abstract

The present invention relates to: an acrylic adhesive composition which includes an acrylic copolymer formed by polymerizing a monomer mixture including an alkyl (meth)acrylate monomer, a (meth)acrylic monomer having a crosslinkable functional group, a (meth)acrylic monomer including a heterocyclic structure, and a monomer represented by chemical formula 1, R^1-CH=CR^2-(C=O)-O-X-Y; and a protective film including an adhesive layer formed by using the same. In chemical formula 1, R^1 is hydrogen, a C1-C6 alkyl group, or a C1-C6 alkenyl group, R^2 is hydrogen or a C1-C10 alkyl group, X is a single bond, a C1-C10 alkylene group, a C2-C10 alkenylene group, an ether, an ester, or a combination thereof and Y is a vinyl group, an allyl group, or a C3-C10 cycloalkenyl group. The acrylic adhesive composition provided by the present invention is able to minimize contamination on the surface of a product.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a pressure-

The present invention relates to a pressure-sensitive adhesive composition and a protective film using the pressure-sensitive adhesive composition, and more particularly, to a pressure-sensitive adhesive composition having excellent coating properties, .

The protective film is used to prevent the surface of the product from being damaged by a physical impact that may occur during transportation, storage, and / or assembly of the product. The protective film is usually applied to one surface or both surfaces of a plastic substrate film such as polyethylene terephthalate An adhesive layer is formed.

When the adhesive force of the protective film is stronger than necessary, it may cause a problem that the surface of the product is damaged or contaminated during the removal process. Particularly, when the protective film is peeled off from the surface of the product after transportation, storage and / There is a problem that peeling is not performed properly at high-speed peeling and workability is deteriorated.

On the other hand, when the adhesive force of the protective film is too low, the adhesive property to the base film is deteriorated and the adhesive agent is transferred to the surface of the product after peeling, resulting in defects such as stains on the product surface. In addition to the contamination by the component transferred from the pressure-sensitive adhesive, moisture and the like may penetrate between the protective film and the product surface to leave stains and the like.

In addition, in the case of conventional pressure sensitive adhesives for protective films, the physical properties of the pressure sensitive adhesive layer are changed with time to increase the adhesive strength and deteriorate stability over time. Particularly, when exposed to high temperatures, And the adhesive layer is transferred to the adherend after peeling, causing contamination.

Therefore, development of a pressure-sensitive adhesive for a protective film which is excellent in stability over time under high temperature conditions and can minimize the occurrence of contamination on the product surface is required.

Korean Patent Publication No. 10-2013-0133721 (December, 2013)

Disclosure of the Invention The present invention has been made in an effort to solve the problems described above, and it is an object of the present invention to provide a pressure-sensitive adhesive composition having excellent heat resistance and excellent stability over time at a high temperature, do.

In one aspect, the present invention relates to a process for producing a polymer (A) comprising a monomer represented by the following formula (1), a (meth) acrylic monomer having a heterocyclic structure, a (meth) acrylic monomer having a crosslinkable functional group, Wherein the acrylic copolymer is formed by polymerizing a monomer mixture comprising the acrylic copolymer.

[Chemical Formula 1]

R ^{1 is} -CH = CR ² - (C = O) -OXY

Wherein R ¹ is hydrogen, a C ¹ to C 6 alkyl group or a C 1 to C 6 alkenyl group, R ² is hydrogen or a C 1 to C 10 alkyl group, X is a single bond, a C 1 to C 10 alkylene group, a C 2 to C 10 alkenylene group , An ether, an ester, or a combination thereof, and Y is a vinyl group, an allyl group, or a C3-C10 cycloalkenyl group.

In another aspect, the present invention provides a protective film comprising a pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive composition according to the present invention.

The pressure-sensitive adhesive composition according to the present invention, including the acrylic copolymer having a branched polymer structure, has a lower viscosity than that of the conventional pressure-sensitive adhesive composition, and can exhibit excellent coating properties.

Further, the pressure-sensitive adhesive composition according to the present invention has excellent heat resistance and little change in the physical properties of the pressure-sensitive adhesive layer even under high temperature conditions.

In addition, the pressure-sensitive adhesive composition according to the present invention has excellent anti-fouling properties because it has less residue as the adhesive after removal of the protective film.

Also, the pressure-sensitive adhesive composition according to the present invention has excellent adhesive strength to various materials such as glass, metal, etc., and is excellent in transparency and can be applied to various fields. For example, the pressure-sensitive adhesive composition according to the present invention can be effectively used as a protective film for automobile or a protective film for optical device.

In the case where the word 'includes', 'having', 'done', etc. are used in this specification, other parts can be added unless '~ only' is used. Unless the context clearly dictates otherwise, including the plural unless the context clearly dictates otherwise.

In interpreting the constituent elements, it is construed to include the error range even if there is no separate description.

In the present specification, " (meth) acrylic " is a general term for acrylic and methacrylic. For example, (meth) acrylate includes methacrylate and acrylate, and (meth) acrylic acid includes acrylic acid and methacrylic acid.

In the present specification, " X to Y " representing the range means " X or more and Y or less ".

As used herein, the term " branched polymer structure " means a polymer structure having two or more long chains grown in different directions.

Hereinafter, the pressure-sensitive adhesive composition according to the present invention will be described in detail.

Pressure-sensitive adhesive composition

(1) Acrylic copolymer

The acrylic pressure sensitive adhesive composition according to the present invention is a pressure sensitive adhesive composition comprising a monomer represented by the following formula (1), a (meth) acrylic monomer having a heterocyclic structure, a (meth) acrylic monomer having a crosslinkable functional group and an alkyl (meth) Based on the total weight of the acrylic copolymer.

[Chemical Formula 1]

R ^{1 is} -CH = CR ² - (C = O) -OXY

Wherein R ¹ is hydrogen, a C ¹ to C 6 alkyl group or a C 1 to C 6 alkenyl group, R ² is hydrogen or a C 1 to C 10 alkyl group, X is a single bond, a C 1 to C 10 alkylene group, a C 2 to C 10 alkenylene group , An ether, an ester, or a combination thereof, and Y is a vinyl group, an allyl group, or a C3-C10 cycloalkenyl group.

The monomer represented by the above formula (1) is for forming an acrylic copolymer having a branched polymer structure. Conventionally, acrylic copolymers having a linear polymer structure in which monomers are polymerized in a single long chain type are mainly used as the acrylic copolymer used in the acrylic pressure-sensitive adhesive. However, when such acrylic copolymers having a linear polymer structure are used, there is a problem in that the viscosity increases as the weight average molecular weight becomes larger, thereby deteriorating the coating property.

According to the studies of the present inventors, it has been found that, when an acrylic copolymer is formed by adding a monomer represented by the above formula (1) as in the present invention, a copolymer having a non-linear branched polymer structure is produced. Specifically, the monomer of the above formula (1) has two or more ethylene groups and radicals can be respectively formed in the free radical polymerization and chains can be grown in different directions. Thus, the monomer having two or more chains Type polymer is formed. Since such an acrylic copolymer having a branched structure has low viscosity characteristics as compared with a linear acrylic copolymer having the same weight average molecular weight, excellent coating properties can be realized.

Specific examples of the monomer represented by the formula (1) include allyl methacrylate, allyl acrylate, methallyl methacrylate, methallyl acrylate, 3-butenyl acrylate, but-3-enyl-2-methylprop-2-enoate, 2-allyloxyethyl Acrylate, 2-allyloxyethyl acrylate, 2-allyloxyethyl methacrylate, 3-allyloxypropyl methacrylate, 3-allyloxypropyl acrylate, 2-allyloxyethoxyethyl methacrylate, 2-allyloxyethoxyethyl acrylate, cyclohex-2-enyl acrylate, cyclohex-2-enyl acrylate, 2-en-1-yl-2-methylprop-2-enoate (cyclo hexyl-2-ene-1-yl-2-methylprop-2-enoate and 3-vinylcyclohex-2-enyl acrylate, , But is not limited thereto.

The monomer represented by the formula (1) may be contained in an amount of 0.01 to 1 part by weight, preferably 0.05 to 0.8 part by weight, more preferably 0.1 to 0.6 part by weight based on 100 parts by weight of the monomer mixture. When the content of the monomer represented by the general formula (1) is less than 0.01 part by weight, it is difficult to prepare a copolymer having a low viscosity. If the content of the monomer is more than 1 part by weight, the crosslinking reaction proceeds during the polymerization reaction, It is difficult to do.

Next, the (meth) acrylic monomer having the heterocyclic structure is intended to improve the heat resistance of the pressure-sensitive adhesive composition, and the heterocyclic structure includes at least one of O, N, S and F atoms Or more. Specifically, the (meth) acrylic monomer having a heterocyclic structure may be, for example, a compound represented by the following formula (2).

(2)

In Formula 2, R ₃ may be hydrogen, a hydroxy group, a C1-10 alkyl group or a C1-10 alkoxy group, a nitro group, or a combination thereof, and R ₄ is hydrogen or a C1-10 alkyl group.

More specifically, the (meth) acrylic monomer having the heterocyclic structure may be at least one selected from the group consisting of compounds represented by the following formulas (2-1) to (2-4).

[Formula 2-1]

[Formula 2-2]

[Formula 2-3]

[Chemical Formula 2-4]

When the monomer having a heterocyclic structure is included as described above, the heat resistance of the pressure-sensitive adhesive composition is improved, and an effect of suppressing a change with time in a high-temperature environment can be obtained. However, when a monomer having a heterocyclic structure is used, the viscosity of the pressure-sensitive adhesive composition increases sharply, resulting in poor coating properties and difficult processing. Thus, in the present invention, a pressure sensitive adhesive composition having both excellent heat resistance and viscosity characteristics can be obtained by forming a branched polymer structure by using a monomer of the formula (1) and a (meth) acrylic monomer containing a heterocyclic structure.

On the other hand, the (meth) acrylic monomer having the heterocyclic structure may be contained in an amount of 1 part by weight or more, preferably 1 to 20 parts by weight, more preferably 3 to 10 parts by weight, based on 100 parts by weight of the monomer mixture. When the content of the (meth) acrylic monomer containing the heterocyclic structure is less than 1 part by weight, the effect of improving the heat resistance is insignificant and it is difficult to suppress the change of the pressure-sensitive adhesive composition over time when exposed to a high temperature. When the content of the (meth) acrylic monomer having a heterocyclic structure is more than 20 parts by weight, it is difficult to control viscosity increase.

Next, the (meth) acrylic monomer having a crosslinkable functional group is to improve the adhesive force and the cohesive force of the pressure-sensitive adhesive composition, and examples thereof include a hydroxy group-containing monomer, a nitrogen-containing monomer, and the like, but are not limited thereto . Specific examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (Meth) acrylate, 2-hydroxyethyleneglycol (meth) acrylate or 2-hydroxypropyleneglycol (meth) acrylate, and examples of the nitrogen-containing monomer include (Meth) acrylamide, N-vinylpyrrolidone or N-vinylcaprolactam, but are not limited thereto.

The (meth) acrylic monomer having a crosslinkable functional group may be contained in an amount of 0.1 to 20 parts by weight, preferably 0.5 to 10 parts by weight, more preferably 1 to 8 parts by weight based on 100 parts by weight of the monomer mixture. When the content of the (meth) acrylic monomer having a crosslinkable functional group satisfies the above range, the adhesion between the adhesion surface and the protective film is excellent. When the content of the (meth) acrylic monomer having a crosslinkable functional group is more than 20 parts by weight, the viscosity of the resin is increased by the crosslinkable functional group and the reaction rate of the crosslinkable functional group and the curing agent is increased, It is difficult to do.

On the other hand, the alkyl (meth) acrylate monomer preferably contains an alkyl group having 2 to 14 carbon atoms. If the alkyl group contained in the alkyl (meth) acrylate monomer is excessively long, the cohesive force of the pressure-sensitive adhesive decreases, and it becomes difficult to control the glass transition temperature (Tg) and tackiness. Examples of the alkyl (meth) acrylate monomer include ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, Acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, lauryl (meth) acrylate and tetradecyl (meth) acrylate. In the present invention, Can be used.

The alkyl (meth) acrylate monomer may be contained in an amount of 84 to 98.89 parts by weight, preferably 89.2 to 96.95 parts by weight, more preferably 90 to 95 parts by weight based on 100 parts by weight of the monomer mixture.

According to one embodiment, the (meth) acrylic copolymer is a copolymer comprising 0.01 to 1 part by weight of a monomer represented by the formula (1); 1 to 20 parts by weight of a (meth) acrylic monomer containing the heterocyclic structure; 84 to 98.89 parts by weight of the alkyl (meth) acrylate monomer; And 1 to 20 parts by weight of a (meth) acrylic monomer having a crosslinkable functional group.

Meanwhile, the monomer mixture according to the present invention may contain acrylic acid monomer in an amount of less than 1 part by weight based on 100 parts by weight of the monomer mixture, but preferably it does not include an acrylic acid monomer. When the acrylic acid monomer is contained in an amount of 1 part by weight or more, corrosion may occur due to contact with a surface including a metal oxide or a metal material such as ITO.

The acrylic copolymer according to the present invention can be prepared by mixing each of the monomers described above to prepare a monomer mixture, and then performing a free-radical polymerization reaction. The polymerization method is not particularly limited, and various polymerization methods known in the art can be used, for example, polymerization methods such as solution polymerization, photopolymerization, bulk polymerization, suspension polymerization or emulsion polymerization. In the polymerization, a polymerization initiator, molecular weight control, and the like may be further added, and the timing of introduction of each component is not particularly limited. That is, the components may be input in a batch or may be divided into several parts.

In the present invention, in particular, an acrylic resin can be produced by a solution polymerization method. Solution polymerization is carried out by adding an initiator, a molecular weight modifier, etc. in a state where each monomer is homogeneously mixed, . ≪ / RTI > Examples of initiators that can be used in this process include azo initiators such as azobisisobutyronitrile or azobiscyclohexanecarbonitrile; And / or peroxides such as benzoyl peroxide, acetyl peroxide, and the like. One or more of the above initiators may be used, but the present invention is not limited thereto. Examples of the molecular weight regulator include mercaptans such as t-dodecyl mercaptan and n-dodecyl mercaptan, terpenes such as dipentin or t-terpene, halogenated hydrocarbons such as chloroform or carbon tetrachloride, or pentaerythritol Tetrakis (3-mercaptopropionate, and the like may be used, but the present invention is not limited thereto.

The acrylic copolymer of the present invention may have a weight average molecular weight of 400,000 to 1,000,000, preferably 500,000 to 700,000. When the weight average molecular weight of the acrylic copolymer is less than 400,000, the cohesive force of the pressure-sensitive adhesive is insufficient due to the lowering of the curing efficiency, and the pressure-sensitive adhesive is transferred upon exposure to the heat-resistant condition. .

The acrylic copolymer preferably has a polymerization conversion rate of 99% or more. When an acrylic copolymer having a polymerization conversion of less than 99% is used, an additional curing reaction proceeds at a high temperature to increase the peeling force, and the residual rate of the adhesive layer on the adhesive agent may be increased after removing the adhesive layer.

In addition, the acrylic copolymer of the present invention has a branched polymer structure. Since the acrylic copolymer having a branched polymer structure has a lower viscosity than a linear acrylic copolymer having the same weight average molecular weight, excellent coating properties can be realized.

(2) Hardener

The curing agent is used for improving the durability of the pressure-sensitive adhesive layer by forming a crosslinked structure. The type of the curing agent is not particularly limited, and various curing agents used in the technical field such as an isocyanate group compound, an epoxy group compound, an aziridine group compound , And metal chelate compounds may be used.

As the isocyanate compound, those known in the art can be used, and examples thereof include toluene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylenediisocyanate, hydrogenated triphenyl diisocyanate, 1,4-diisocyanate, 1,3-bisisocyanatomethylcyclohexane, tetramethylxylene diisocyanate, 1, 1-xylylene diisocyanate, 1, , 5-naphthalene diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, trimethylolpropane-modified toluene diisocyanate, trimethylolpropane- Diisocyanate, trilene diisocyanate adduct of trimethylol propane, trimethyl Xylene video isocyanate propanoic air ducts, storage methane storage diisocyanate, methylene bis triisocyanate, those of the polyol (trimethylol propane) or a mixture thereof and the like.

Examples of the epoxy compound include ethylene glycol diglycidyl ether, triglycidyl ether, trimethylol propane triglycidyl ether, N, N, N ', N'-tetraglycidyl ethylenediamine, glycerin Diglycidyl ether, a mixture thereof and the like can be used.

Examples of the aziridine compound include N, N'-toluene-2,4-bis (1-aziridinecarboxamide), N, N'-diphenylmethane-4,4'- (2-methyl aziridine), tri-1-aziridinyl phosphine oxide, or a mixture thereof may be used.

Examples of the metal chelate compound include compounds in which a polyvalent metal such as aluminum, iron, zinc, tin, titanium, antimony, magnesium and / or vanadium is coordinated to acetylacetone or ethyl acetoacetate , But is not limited thereto.

The curing agent is preferably contained in an amount of 0.1 to 10 parts by weight, preferably 0.2 to 7 parts by weight, more preferably 0.5 to 5 parts by weight based on 100 parts by weight of the acrylic copolymer. When the curing agent of less than 0.1 is used, the pressure-sensitive adhesive may be transferred to the adherend surface when peeling off the protective film after high temperature exposure due to the lack of crosslinking degree. When the curing agent is used in an amount of 10 parts by weight or more, the coating property is poor. , Or may cause a change in the adhesive force with time.

(3) Other components

The pressure-sensitive adhesive composition of the present invention may further contain other components such as a solvent, a silane coupling agent, a crosslinking catalyst, a tackifier resin, an additive and the like in addition to the above-mentioned components for property control.

The pressure-sensitive adhesive composition of the present invention may further comprise a solvent for viscosity control. The solvent may include, for example, ethyl acetate, n-pentane, isopentane, neopentane, n-hexane, n-octane, n-heptane, methyl ethyl ketone, acetone, toluene, But is not limited thereto.

Further, the pressure-sensitive adhesive composition of the present invention may further comprise a silane coupling agent.

Such a coupling agent is intended to improve the adhesion between the pressure-sensitive adhesive and the substrate and the adhesion stability. Examples of the coupling agent that can be used in the present invention include? -Glycidoxypropyltriethoxysilane,? -Glycidoxypropyltrimethoxysilane,? -Glycidoxypropylmethyldiethoxysilane,? -Glycidoxy Propyltrimethoxysilane, propyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane,? -Methacryloxypropyltrimethoxysilane,? -Methacryloxypropyltriethoxysilane, aminopropyltrimethoxysilane, gamma -aminopropyltrimethoxysilane, gamma -aminopropyltriethoxysilane, 3-isocyanatopropyltriethoxysilane, gamma -acetoacetylpropyltrimethoxysilane, gamma -acetoacetylpropyltriethoxysilane, ? -cyanoacetyltrimethoxysilane,? -cyanoacetyltriethoxysilane and acetoxyacetotrimethoxysilane, and mixtures of one or more of the above can be used. In the present invention, it is preferable to use a silane-based coupling agent having an acetoacetate group or a? -Cyanoacetyl group, but the present invention is not limited thereto.

The silane coupling agent in the composition of the present invention may be contained in an amount of 0.01 to 5 parts by weight, preferably 0.01 to 1 part by weight, based on 100 parts by weight of the acrylic copolymer. If the content of the coupling agent is less than 0.01 parts by weight, the effect of increasing the adhesiveness is insignificant. If the content exceeds 5 parts by weight, durability may be deteriorated.

The pressure-sensitive adhesive composition of the present invention may further comprise 1 part by weight to 100 parts by weight of a tackifying resin, based on 100 parts by weight of the acrylic copolymer, from the viewpoint of controlling the tacking performance. Examples of such a tackifier resin include, but are not limited to, (hydrogenated) hydrocarbon resin, hydrogenated rosin resin, hydrogenated rosin ester resin, hydrogenated terpene resin, hydrogenated terpene phenol resin, A polymerized rosin resin, a polymerized rosin ester resin and the like, or a mixture of two or more thereof. When the content of the tackifier resin is less than 1 part by weight, the effect of addition may be insignificant. When the content of the tackifier resin is more than 100 parts by weight, there is a fear that the effect of improving compatibility and / or cohesive strength is lowered.

The pressure-sensitive adhesive composition of the present invention may also contain one or more additives selected from the group consisting of epoxy resins, curing agents, ultraviolet stabilizers, antioxidants, colorants, reinforcing agents, fillers, defoamers, surfactants and plasticizers, . ≪ / RTI >

The pressure-sensitive adhesive composition according to the present invention containing the above-mentioned components has a lower viscosity than that of the conventional pressure-sensitive adhesive composition, and can exhibit excellent coating properties.

Also, the pressure-sensitive adhesive composition according to the present invention includes a heterocyclic structure and is excellent in heat resistance and has little change in the physical properties of the pressure-sensitive adhesive layer even under high temperature conditions.

Also, the pressure-sensitive adhesive composition according to the present invention has excellent adhesive strength to various materials such as glass, metal, etc., and is excellent in transparency and can be applied to various fields. For example, the pressure-sensitive adhesive composition according to the present invention can be effectively used as a protective film for automobile or a protective film for optical device.

Protective film

Next, the protective film according to the present invention will be described. The protective film of the present invention comprises an adhesive layer formed by the pressure-sensitive adhesive composition according to the present invention. More specifically, the protective film according to the present invention may include a base film and an adhesive layer formed on one side or both sides of the base film and formed by the pressure-sensitive adhesive composition according to the present invention.

As the base film, various films used as a base material of a protective film in the related art, for example, polyethylene, polyethylene terephthalate, polypropylene, polyester, polyamide, polyimide, polycarbonate, ethylene- And synthetic resin films such as polyethylene terephthalate, polyethylene terephthalate, polyethylene terephthalate, polyethylene terephthalate, polyethylene terephthalate, polyethylene terephthalate, polyethylene terephthalate, polyethylene terephthalate, polyethylene terephthalate, polyethylene terephthalate, polyethylene terephthalate,

The base film may be a single layer or a multi-layer body, and may have a thickness of about 5 to 500 탆.

The surface of the substrate film may be subjected to surface treatment such as corona discharge treatment, plasma treatment, blast treatment, chemical etching treatment, primer treatment, etc., in order to improve adhesion to the adhesive layer.

On the other hand, the adhesive layer may be formed by applying the pressure-sensitive adhesive composition according to the present invention onto the base film and then drying the applied pressure-sensitive adhesive composition. The application can be generally performed by a knife coater, a roll coater, a calendar coater, a comma coater, or the like. Depending on the coating thickness or the viscosity of the coating liquid, it may be performed by a gravure coater, a rod coater or the like.

On the other hand, the drying can be carried out at a temperature of, for example, 60 ° C to 150 ° C, preferably 70 ° C to 120 ° C for 1 minute to 10 minutes.

Further, if necessary, an aging step for completing the crosslinking reaction after the drying step is completed can be further carried out. The aging process can be carried out, for example, at a temperature ranging from 25 DEG C to 90 DEG C for 1 to 7 days.

The protective film of the present invention as described above is excellent in the adhesive force at room temperature and has little change in physical properties of the pressure-sensitive adhesive layer even under high-temperature conditions. Specifically, the protective film The rate of change in adhesive force defined by the following formula (1) is 30% or less, preferably 20% or less, more preferably 15% or less.

(1): Adhesive force change rate (%) = (A ₁ -A ₀ / A ₀ ) × 100

In the above formula (1), A ₀ is the adhesive strength measured after attaching the protective film on a glass substrate, A ₁ is a protective film which is aged at 70 ° C for 5 days on a glass substrate, It is a cohesive force.

Example

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

Manufacturing example  1: Production of acrylic copolymer (A)

94.7 parts by weight of butyl acrylate (BA), 4.0 parts by weight of hydroxybutyl acrylate (HBA), 4.0 parts by weight of isosorbide acrylate (ISA) 1 , And 0.18 part by weight of allyl methacrylate (AMA), and 60 parts by weight of ethyl acetate (EAc) was added as a solvent. Nitrogen gas was then purged for 60 minutes to remove oxygen, and then the temperature was maintained at 70 占 폚. Then, 0.23 part by weight of n-dodecylmercaptan (n-DDM) as a molecular weight modifier, 0.15 part by weight of azobis (2-4-dimethylvaleronitrile (V-65, manufacturer: Wako) (A) was added thereto in an amount of 0.12 part by weight for 10 hours to prepare an acrylic copolymer (A). The allyl methacrylate was added after 3 hours of reaction time, and the molecular weight adjuster was reacted for 5 hours , And the polymerization initiator was added to the reaction mixture in 10 times until the reaction time was 7 hours while confirming the degree of heat generation.

Manufacturing example  2: Production of acrylic copolymer (B)

92.7 parts by weight of butyl acrylate (BA), 4.0 parts by weight of hydroxybutyl acrylate (HBA), 4.0 parts by weight of isosorbide acrylate (ISA) 3 , And 0.18 part by weight of allyl methacrylate (AMA), and 60 parts by weight of ethyl acetate (EAc) was added as a solvent. Nitrogen gas was then purged for 60 minutes to remove oxygen, and then the temperature was maintained at 70 占 폚. Then, 0.21 part by weight of a molecular weight regulator n-dodecylmercaptan (n-DDM), 0.15 part by weight of a polymerization initiator azobis (2-4-dimethylvaleronitrile (V-65, manufacturer: Wako) AMA) as a polymerization initiator was added thereto for 10 hours to prepare an acrylic copolymer (B). The allyl methacrylate was added 3 hours after the reaction time, The polymerization initiator was added in 10 divided cycles up to a reaction time of 7 hours while confirming the degree of heat generation.

Manufacturing example  3: Production of acrylic copolymer (C)

90.7 parts by weight of butyl acrylate (BA) and 4.0 parts by weight of hydroxybutyl acrylate (HBA), 4.0 parts by weight of isosorbide acrylate (ISA) 5 , And 0.18 part by weight of allyl methacrylate (AMA), and 60 parts by weight of ethyl acetate (EAc) was added as a solvent. Nitrogen gas was then purged for 60 minutes to remove oxygen, and then the temperature was maintained at 70 占 폚. Then, 0.20 part by weight of n-dodecylmercaptan (n-DDM) as a molecular weight modifier, 0.15 part by weight of azobis (2-4-dimethylvaleronitrile (V-65, manufacturer: Wako) AMA) was added to the reaction mixture for 10 hours to prepare an acrylic copolymer (C). The allyl methacrylate was added after 3 hours of reaction time, and the molecular weight adjuster was added to the reaction mixture for 5 hours The polymerization initiator was added in 10 divided cycles up to a reaction time of 7 hours while confirming the degree of heat generation.

Manufacturing example  4: Production of acrylic copolymer (D)

95.7 parts by weight of butyl acrylate (BA), 4.0 parts by weight of hydroxybutyl acrylate (HBA), and 0.18 part by weight of allyl methacrylate (AMA) 0.18 parts by weight were added to a 3 L reactor equipped with a cooling device for nitrogen gas flow- , And 60 parts by weight of ethyl acetate (EAc) was added as a solvent. Nitrogen gas was then purged for 60 minutes to remove oxygen, and then the temperature was maintained at 70 占 폚. Then, 0.23 part by weight of n-dodecylmercaptan (n-DDM) as a molecular weight modifier, 0.15 part by weight of polymerization initiator azobis (2-4-dimethylvaleronitrile (V-65, manufacturer: Wako) AMA) was added to the reaction mixture for 10 hours to prepare an acrylic copolymer (D). The allyl methacrylate was added 3 hours after the reaction time, and the molecular weight adjuster was changed to 5 The polymerization initiator was added in 10 divided cycles up to a reaction time of 7 hours while confirming the degree of heat generation.

Manufacturing example  5: Preparation of acrylic copolymer (E)

93 parts by weight of butyl acrylate (BA), 4.0 parts by weight of hydroxybutyl acrylate (HBA), and 4.0 parts by weight of isosorbide acrylate (ISA) were added to a 3 L reactor equipped with a cooling device for nitrogen gas flow- , And 60 parts by weight of ethyl acetate (EAc) were added as a solvent. Nitrogen gas was then purged for 60 minutes to remove oxygen, and then the temperature was maintained at 70 占 폚. Then, 0.05 part by weight of a polymerization initiator azobis (2-4-dimethylvaleronitrile (V-65, manufacturer: Wako) was added and reacted for 10 hours to prepare an acrylic copolymer (E).

The weight average molecular weight and the polymer structure of the acrylic copolymer prepared in Preparation Examples 1 to 5 were measured as follows and shown in Table 1.

(1) Weight average molecular weight:

The weight average molecular weight was measured by GPC under the following conditions. For the calibration curve, the measurement results were converted using standard polystyrene of the Agilent system.

<Measurement Conditions>

Meter: Agilent GPC (Agulent 1200 series, USA)

Column: Two PL Mixed B connections

Column temperature: 40 ° C

Eluent: tetrahydrofuran

Flow rate: 1.0 mL / min

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

(2) Polymer structure:

First, an alkyl (meth) acrylate monomer of the same kind as that used in the acrylic copolymer to be evaluated for polymer structure (hereinafter, referred to as "evaluation target copolymer"), a (meth) acrylic monomer containing a heterocyclic structure And a (meth) acrylic monomer having a crosslinkable functional group were mixed to prepare a monomer mixture. At this time, the content of the (meth) acrylic monomer having a heterocyclic structure in the monomer mixture and the content of the (meth) acrylic monomer having a crosslinkable functional group is in the range of (meth) acrylic monomer containing a heterocyclic structure in the evaluation target copolymer, (Meth) acrylic monomer having a maleic functional group. Then, the above-mentioned monomer mixture was polymerized to prepare an acrylic copolymer (hereinafter, referred to as a 'reference copolymer') having the same level of weight average molecular weight (error range ± 5%) as that of the copolymer to be evaluated.

Then, ethyl acetate solvent was added to each of the reference copolymer and the evaluation target copolymer to adjust the solid concentration to 30%, and the viscosity was measured. When the viscosity of the copolymer to be measured as described above had a viscosity lower than the viscosity of the reference copolymer by 30% or more, it was evaluated to have a branched polymer structure, and in other cases, it was evaluated to have a linear polymer structure .

division Production Example 1 Production Example 2 Production Example 3 Production Example 4 Production Example 5 sample A B C D E Furtherance BA 94.7 92.7 90.7 95.7 93.0 HBA 4.0 4.0 4.0 4.0 4.0 ISA 1.0 3.0 5.0 - 5.0 AMA 0.3 0.3 0.3 0.3 - n-DDM 0.23 0.21 0.20 0.23 0 Weight average molecular weight (Mw) 570,000 650,000 640,000 560,000 1,600,000 Polymer structure Branches Branches Branches Branches Linear

Example  One

100 parts by weight of the acrylic copolymer A prepared in Preparation Example 1 and 4 parts by weight of a curing agent (coronate L, manufactured by Nippon Polyurethane Industry Co., Ltd.) were mixed to prepare a pressure-sensitive adhesive composition (coating liquid).

The pressure-sensitive adhesive composition was coated on a polyethylene terephthalate (PET) film, dried at 90 ° C for 4 minutes, and aged at 50 ° C for 2 days to prepare a protective film.

Example  2

A pressure-sensitive adhesive composition and a protective film were prepared in the same manner as in Example 1, except that the acrylic copolymer B prepared in Preparation Example 2 was used instead of the acrylic copolymer A prepared in Preparation Example 1.

Example  3

A pressure-sensitive adhesive composition and a protective film were prepared in the same manner as in Example 1, except that the acrylic copolymer C prepared in Preparation Example 3 was used instead of the acrylic copolymer A prepared in Preparation Example 1.

Comparative Example  One

A pressure-sensitive adhesive composition and a protective film were prepared in the same manner as in Example 1, except that the acrylic copolymer D prepared in Preparation Example 4 was used in place of the acrylic copolymer A prepared in Preparation Example 1.

Comparative Example  2

A pressure-sensitive adhesive composition and a protective film were prepared in the same manner as in Example 1, except that the acrylic copolymer E prepared in Preparation Example 5 was used instead of the acrylic copolymer A prepared in Preparation Example 1.

The physical properties of the pressure-sensitive adhesive composition and the protective film prepared in Examples 1 to 3 and Comparative Examples 1 and 2 were measured by the following methods. The measurement results are shown in Table 2 below.

How to measure property

1. Coating viscosity [unit: cP]

The coating viscosity of the pressure-sensitive adhesive composition was evaluated according to the following procedure using a Brookfield digital viscometer (RV DV2T).

220 mL of the pressure-sensitive adhesive composition was placed in a 250 mL PE bottle, the lid was closed to prevent volatilization of the solvent, the membrane was sufficiently sealed with a para-film, and the bubbles were sufficiently removed under constant temperature / humidity conditions (23 ° C., 50% relative humidity). Then, after the seal and the lid were removed, the spindle was connected to a viscometer so as to prevent air bubbles from forming in the pressure-sensitive adhesive composition, and the liquid level of the pressure-sensitive adhesive composition was adjusted to fit the groove of the spindle. Thereafter, the viscosity was measured at an rpm condition in which the torque was 20% (± 1%).

2. Coating property

When the pressure-sensitive adhesive composition prepared in Examples and Comparative Examples was coated on a polyethylene terephthalate film, the state of the coating layer was visually observed and evaluated according to the following criteria.

&Lt; Evaluation criteria of coating property &

OK: No visible bubbles or streaks on the coating layer.

NG: Bubbles and / or streaks on the coating layer are visually confirmed.

3. Adhesion at room temperature [Unit: gf / 25mm]

The protective films prepared according to Examples and Comparative Examples were respectively attached to a non-alkali glass substrate and an SUS substrate, and were stored under constant temperature and humidity conditions (23 DEG C, 50% R.H.) for 4 hours. Then, by using a TA equipment (Texture Analyzer, Stable Microsystems, UK), the protective film was pulled out under the conditions of a peeling speed of 300 mm / min and a peeling angle of 180 degrees to obtain a force required to completely separate the protective film from the substrate , And evaluated by its normal-temperature cohesive force (unit: gf / 25 mm).

4. Adhesion after aging [Unit: gf / 25 mm] and the rate of change of adhesive force [unit: % ] evaluation

The protective films prepared according to Examples and Comparative Examples were aged at 70 ° C for 5 days, and then aged protective films were attached to the alkali-free glass substrates, respectively, and the films were subjected to constant temperature and humidity (23 ° C., 50% Lt; / RTI &gt; Then, by using a TA equipment (Texture Analyzer, Stable Microsystems, UK), the protective film was pulled out under the conditions of a peeling speed of 300 mm / min and a peeling angle of 180 degrees to obtain a force required to completely separate the protective film from the substrate And the adhesive strength (unit: gf / 25 mm) was evaluated after aging.

In addition, the adhesive strength (%) at room temperature of the protective film adhered on the alkali-free glass substrate in ( ₃ ) above and the adhesion force after aging (A ₁ )

(1): Adhesive force change rate (%) = (A ₁ -A ₀ / A ₀ ) × 100

5. Evaluation of stain resistance

The protective films prepared according to Examples and Comparative Examples were attached to alkali-free glass to prepare test specimens, and the test specimens were allowed to stand at 120 DEG C for 4 hours. Then, the protective film was removed from the glass, and whether the residue or unevenness occurred on the glass was visually observed to evaluate the stain resistance at high temperature.

Further, the measurement specimen was left for 72 hours at a temperature of 60 DEG C and a relative humidity of 90% R.H. Then, the protective film was removed from the glass, and whether the residue or unevenness occurred on the glass was visually observed to evaluate the stain resistance at high temperature / high humidity conditions.

The case where the residue and the unevenness were not observed on the glass after the removal of the protective film was evaluated as OK, and the case where the residue or unevenness was observed was evaluated as NG.

Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Furtherance
(Parts by weight) Acrylic copolymer A B C D E 100 100 100 100 100 Hardener 4.0 4.0 4.0 4.0 4.0 Coating viscosity (cP) 290 330 600 240 5000 Coating property OK OK OK OK NG Adhesion at room temperature
[gf / 25mm] Glass 7.2 9.1 11.2 4.9 4.0 SUS 9.5 12.2 15.3 5.6 5.1 Adhesion after aging
[gf / 25mm] 8 10 12 8 7 Adhesive force change rate [%] 11.1 9.9 7.2 64.1 37.5 Stain resistance High temperature condition OK OK OK NG OK High temperature / high humidity condition NG OK OK NG NG

As shown in Table 2, the pressure-sensitive adhesive compositions of Examples 1 to 3 have low coating viscosity, small rate of change of adhesive force with time, and excellent stain resistance even under high temperature conditions. In addition, it can be confirmed that the glass substrate and the SUS substrate have excellent tackiness.

On the other hand, the pressure-sensitive adhesive composition of Comparative Example 1 using the acrylic copolymer D prepared without using a monomer having a heterocyclic structure had poor adhesion to the SUS substrate, a large change with time in the pressure-sensitive adhesive layer, It can be confirmed that the pollution is also lowered. In addition, the pressure-sensitive adhesive composition of Comparative Example 2 using the acrylic copolymer E prepared without using the monomer of the formula (1) had too low a coating property due to too high a coating viscosity, a poor adhesion to a substrate, , Respectively.

Claims (15)

A monomer represented by the following formula (1)
(Meth) acrylic monomer containing a heterocyclic structure,
(Meth) acrylic monomer having a crosslinkable functional group, and
Wherein the acrylic copolymer is formed by polymerizing a monomer mixture comprising an alkyl (meth) acrylate monomer.
[Chemical Formula 1]
R ^{1 is} -CH = CR ² - (C = O) -OXY
Wherein R ¹ is hydrogen, a C ¹ to C 6 alkyl group or a C 1 to C 6 alkenyl group, R ² is hydrogen or a C 1 to C 10 alkyl group, X is a single bond, a C 1 to C 10 alkylene group, a C 2 to C 10 alkenylene group , An ether, an ester, or a combination thereof, and Y is a vinyl group, an allyl group, or a C3-C10 cycloalkenyl group.
The method according to claim 1,
Wherein the acrylic copolymer has a polymerization conversion of 99 wt% or more.
The method according to claim 1,
Wherein the acrylic copolymer is a polymer having a branched structure.
The method according to claim 1,
Wherein the acrylic copolymer has a weight average molecular weight of 400,000 to 1,000,000.
The method according to claim 1,
The monomer represented by the formula (1) may be at least one selected from the group consisting of allyl methacrylate, allyl acrylate, methallyl methacrylate, methallyl acrylate, Butenyl acrylate, but-3-enyl-2-methylprop-2-enoate, 2-allyloxyethyl acrylate (2 allyloxyethyl methacrylate, 3-allyloxypropyl methacrylate, 3-allyloxypropyl acrylate, 2-allyloxyethoxyethyl acrylate, 2-allyloxyethyl methacrylate, 2-allyloxyethoxyethyl methacrylate, 2-allyloxyethoxyethyl acrylate, cyclohex-2-enyl acrylate, cyclohex-2-ene acrylate, Cyclohex-2-en-1-yl 2-methylpyr-2-enoate op-2-enoate, and 3-vinylcyclohex-2-enyl acrylate.
The method according to claim 1,
Wherein the (meth) acrylic monomer having a heterocyclic structure is a compound represented by the following formula (2).
(2)

In Formula 2, R ₃ may be hydrogen, a hydroxy group, a C 1-10 alkyl group, a C 1-10 alkoxy group, a nitro group, or a combination thereof, and R ₄ is hydrogen or a C 1-10 alkyl group.
The method according to claim 1,
Wherein the (meth) acrylic monomer having a heterocyclic structure is selected from the group consisting of compounds represented by the following general formulas (2-1) to (2-4).
[Formula 2-1]

[Formula 2-2]

[Formula 2-3]

[Chemical Formula 2-4]

The method according to claim 1,
Wherein the (meth) acrylic acid monomer is contained in an amount of less than 1 part by weight based on 100 parts by weight of the monomer mixture.
The method according to claim 1,
Wherein the monomer mixture comprises 0.01 to 1 part by weight of the monomer represented by the formula (1) based on 100 parts by weight of the monomer mixture.

The method according to claim 1,
Wherein the monomer mixture comprises 1 to 20 parts by weight of a (meth) acrylic monomer containing the heterocyclic structure, based on 100 parts by weight of the monomer mixture.
The method according to claim 1,
With respect to 100 parts by weight of the monomer mixture,
0.01 to 1 part by weight of a monomer represented by the above formula (1);
1 to 20 parts by weight of a (meth) acrylic monomer containing the heterocyclic structure;
84 to 98.89 parts by weight of the alkyl (meth) acrylate monomer; And
And 0.1 to 20 parts by weight of a (meth) acrylic monomer having a crosslinkable functional group.
The method according to claim 1,
Wherein the pressure-sensitive adhesive composition further comprises a curing agent.
13. The method of claim 12,
Wherein the curing agent is contained in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the acrylic copolymer.
A protective film comprising a pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive composition according to any one of claims 1 to 13.
15. The method of claim 14,
Wherein the protective film has a rate of change in adhesive force of 30% or less as defined by the following formula (1).
(1): Adhesive force change rate (%) = (A ₁ -A ₀ / A ₀ ) × 100
In the above formula (1), A ₀ is the adhesive strength measured after attaching the protective film on a glass substrate, A ₁ is a protective film which is aged at 70 ° C for 5 days on a glass substrate, One cohesive force.