KR101750589B1 - Solvent-type adhesive composition by photopolymerisation - Google Patents

Abstract

And an acrylic copolymer resin having a weight average molecular weight of 2,000,000 or more, wherein the acrylic copolymer resin has a molecular Dispersion Index (PolyDispersity Index) of 5 or less.
A substrate; And a pressure-sensitive adhesive layer formed on the substrate and including the solvent-type pressure-sensitive adhesive composition.

Description

[0001] SOLVENT-TYPE ADHESIVE COMPOSITION BY PHOTOLOGYMERISATION [0002]

A pressure-sensitive adhesive layer comprising the pressure-sensitive adhesive composition, and a pressure-sensitive adhesive film comprising the pressure-sensitive adhesive layer.

BACKGROUND ART Pressure-sensitive adhesive sheets prepared by forming a pressure-sensitive adhesive layer on a base film are widely used in various industrial fields including advertising pressure-sensitive adhesive sheets, decorative pressure-sensitive adhesive sheets, industrial protective films, optical pressure-sensitive adhesive sheets and adhesive sheets for electronic parts.

At this time, the pressure-sensitive adhesive sheet is applied to a certain field and requires excellent peeling force along with peeling force to maintain excellent operation or a constant storage life. In recent years, the peeling force of a next generation device such as an OLED or a touch screen There is a growing need for a pressure-sensitive adhesive composition which is excellent in cuttability and workability and can greatly improve the yield of the pressure-sensitive adhesive film.

One embodiment of the present invention provides a solvent-based pressure-sensitive adhesive composition comprising a high molecular weight acrylic copolymer resin.

Another embodiment of the present invention provides an adhesive film comprising a pressure-sensitive adhesive layer formed of the solvent-type pressure-sensitive adhesive composition.

In one embodiment of the present invention, there is provided a solvent-type pressure-sensitive adhesive composition comprising an acrylic copolymer resin having a weight average molecular weight of 2,000,000 or more, wherein the acrylic copolymer resin has a molecular weight distribution (PolyDispersity Index) of about 5 or less.

The acrylic copolymer resin may be formed by photopolymerizing a mixture of a (meth) acrylic acid ester monomer, a functional group-containing monomer, a photopolymerization initiator, and an organic solvent.

The organic solvent may be about 10 parts by weight to about 900 parts by weight based on 100 parts by weight of the (meth) acrylate monomer.

When the photopolymerization proceeds, the viscosity of the acrylic copolymer resin may be about 1,000 cps to about 40,000 cps at room temperature.

The organic solvent is selected from the group consisting of ethyl ether, acetone, acetonitrile, petroleum ether, isopropyl alcohol, methanol, ethanol, n-pentane, n-hexane, benzene, dichloromethane, trichloromethane, methyl acetate, ethyl acetate, , Methyl ethyl ketone, trichloromethane, tetrachloromethane, 1,2-dichloroethane, 1,1,1-trichloroethane, n-hexane, cyclohexane, and combinations thereof.

About 80 parts by weight to about 99.9 parts by weight of the (meth) acrylic acid ester monomer and about 0.01 to about 10 parts by weight of the crosslinkable monomer.

The (meth) acrylate monomer may be at least one selected from the group consisting of methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (Meth) acrylate, isononyl (meth) acrylate, isononyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, Ethylbutyl (meth) acrylate, and combinations thereof.

The functional group-containing monomer may be at least one selected from the group consisting of a hydroxyl group-containing monomer, a carboxyl group-containing monomer, a nitrogen-containing monomer, and combinations thereof.

The photopolymerization initiator may be at least one selected from the group consisting of a benzoin compound, a hydroxy ketone compound, an amino ketone compound, a phosphine oxide compound, and combinations thereof.

The photopolymerization initiator may be about 0.1 part by weight to about 5 parts by weight based on 100 parts by weight of the (meth) acrylate monomer.

A crosslinking agent may be further included.

The crosslinking agent may be an aziridine crosslinking agent.

The crosslinking agent may be included in an amount of about 0.02 part by weight to about 2.0 parts by weight based on 100 parts by weight of the acrylic copolymer resin.

In another embodiment of the present invention, a substrate; And a pressure-sensitive adhesive layer formed on the substrate and including the solvent-type pressure-sensitive adhesive composition.

The thickness of the pressure-sensitive adhesive layer may be about 5 탆 to about 200 탆.

The solvent-type pressure-sensitive adhesive composition can be formed by proceeding a rapid and stable polymerization reaction by light irradiation.

The adhesive film is excellent in re-peeling property, bending adhesion holding force, peeling force and adhesive force, excellent in cutting property and workability, and can realize stable property at high temperature.

Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited thereto, and the present invention is only defined by the scope of the following claims.

Solvent-type pressure-sensitive adhesive composition

In one embodiment of the present invention, there is provided a solvent-type pressure-sensitive adhesive composition comprising an acrylic copolymer resin having a weight average molecular weight of not less than 2,000,000, wherein the acrylic copolymer resin has a polyisocyanate index (PDI) of 5 or less.

The solvent-type pressure-sensitive adhesive composition is a concept collectively referred to as a pressure-sensitive adhesive composition except for a water-based pressure-sensitive adhesive composition such as an aqueous dispersion type or an emulsion type pressure-sensitive adhesive composition. Examples thereof include an organic solvent-type pressure-sensitive adhesive composition prepared by dispersing each component of a composition in an appropriate organic solvent .

The acrylic copolymer resin contained in the solvent-type pressure-sensitive adhesive composition may have a weight average molecular weight of about 2,000,000 or more. The weight average molecular weight is an average molecular weight obtained by averaging the molecular weights of component molecular species of a polymer compound having a molecular weight distribution by weight percentage. For example, the molecular weight of the acrylic copolymer resin may be about 2,000,000 to about 6,000,000 .

Conventionally, the acrylic copolymer resin is prepared by thermal polymerization. As the molecular weight increases, the stirring viscosity and the viscosity of the acrylic copolymer resin are increased. As a result, the stirring and processing of the acrylic polymer resin during polymerization are difficult and it is difficult to secure a high molecular weight acrylic copolymer resin there was. On the other hand, since the acrylic copolymer resin is formed by photopolymerization, in addition to the (meth) acrylic acid ester monomer and the functional group-containing monomer, a photopolymerization initiator that initiates an initiation reaction by light irradiation is used. By performing stable polymerization within a relatively short reaction time within about 2 hours, an acrylic copolymer resin having a weight average molecular weight of about 2,000,000 or more can be obtained.

The light irradiation can be performed through ultraviolet irradiation or the like, and can be carried out by means of, for example, a high pressure mercury lamp, an electrodeless lamp, or a xenon lamp. The ultraviolet irradiation dose is not particularly limited as long as it is controlled to such an extent that sufficient curing can be achieved without impairing all properties, for example, an illuminance of about 50 mW / cm ² to about 1,000 mW / cm ² , / cm ² to about 1,000 mJ / cm ² may be.

When the acrylic copolymer resin has a weight average molecular weight of about 2,000,000 or more, it is possible to secure a solvent-type pressure-sensitive adhesive composition excellent in cutting and workability and having mechanical strength and stable physical properties even at a high temperature, and the application field of the solvent- can do. More specifically, by keeping the molecular weight of about 2,000,000 to about 4,000,000, the durability is excellent even in a high temperature and high humidity environment, and the effect of suppressing cloudiness or bubble generation can be easily realized. In addition, since the reworkability can be improved, when the optical film or the like is adhered to an adherend by using an adhesive composition, if a problem such as foreign matter is involved, the optical film is peeled off from the adherend It refers to ease of affixing the film.

On the other hand, when the molecular weight is less than about 2,000,000, sufficient cohesive force can not be obtained in the pressure-sensitive adhesive composition in a high temperature and high humidity environment and there is a fear of clouding or bubble formation. When the molecular weight exceeds about 400,000, The coating uniformity may be deteriorated.

The molecular weight distribution of the acrylic copolymer resin may be about 5 or less, specifically about 3.5 or less. The ordinary polymer compound is a compound of a molecular species having a different molecular weight and has a polydispersity in molecular weight, so that the high molecular weight acrylic copolymer resin may have a molecular weight distribution. The molecular weight distribution refers to the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn), and can be measured using gel permeation chromatography (GPC). The larger the molecular weight distribution, And the smaller the molecular weight distribution, the more the molecular weight is distributed around the weight average molecular weight.

As the molecular weight distribution becomes wider, the shear stress decreases and the workability improves. However, the mechanical strength and durability of the pressure-sensitive adhesive composition deteriorate. As the molecular weight distribution narrows, the mechanical strength and durability are improved, but the workability may be lowered.

When the molecular weight distribution is not more than about 5, the pressure-sensitive adhesive composition is excellent in not only the mechanical strength and durability but also the processability thereof. In addition, if the molecular weight distribution is out of the above range, the mechanical strength and durability may be deteriorated, Lt; / RTI > Specifically, the molecular weight distribution may be about 2 to 4, and when the molecular weight distribution is less than about 2, the synthesis progress may not be sustained when the acrylic copolymer resin is synthesized with a solvent-type pressure-sensitive adhesive composition.

The acrylic copolymer resin may be formed by photopolymerizing a mixture of a (meth) acrylic acid ester monomer, a functional group-containing monomer, a photopolymerization initiator, and an organic solvent. Specifically, after a mixed solution is prepared by stirring a (meth) acrylic acid ester monomer, a functional group-containing monomer and an organic solvent, dissolved oxygen is removed in the mixed solution, the temperature of the mixed solution is kept constant, After the mixture is formed by adding it, it is possible to initiate the polymerization reaction by irradiating a certain amount of ultraviolet rays.

More specifically, by including a photopolymerization initiator in which a stable polymerization reaction can proceed within a relatively short reaction time within about 2 hours by irradiating ultraviolet light to the mixture and an initiating reaction is caused by ultraviolet rays, a temperature below room temperature, that is, It is not necessary at all.

The organic solvent may be about 10 parts by weight to about 900 parts by weight based on 100 parts by weight of the (meth) acrylate monomer. By including the organic solvent within the above range, it is possible to solve the problem that stirring and processing become difficult due to a rapid increase in viscosity as the molecular weight increases upon photopolymerization.

When the photopolymerization proceeds, the viscosity of the acrylic copolymer resin may be about 1,000 cps to about 40,000 cps at room temperature. Specifically, the viscosity of the acrylic copolymer resin at room temperature may range from about 2,000 cps to about 25,000 cps, more specifically from about 3,000 cps to about 8,000 cps.

By controlling the viscosity of the acrylic copolymer resin within the above range, excellent processability can be maintained during the formation of the solvent-type pressure-sensitive adhesive composition, and a high molecular weight acrylic copolymer resin can be formed.

The kind of the organic solvent is not particularly limited. However, when the drying time of the organic solvent is excessively long or when drying at a high temperature is required, problems may arise in terms of workability or durability of the solvent-type pressure-sensitive adhesive composition, so that it is preferable to use a solvent having a volatilization temperature of about 100 ° C or less desirable. In consideration of the moldability of the solvent-type pressure-sensitive adhesive composition, a small amount of an organic solvent having a volatilization temperature higher than the above range may be mixed and used.

For example, the organic solvent is selected from the group consisting of ethyl ether, acetone, acetonitrile, petroleum ether, isopropyl alcohol, methanol, ethanol, n-pentane, n-hexane, benzene, dichloromethane, trichloromethane, methyl acetate, One selected from the group consisting of ethylene glycol dimethyl ether, methyl ethyl ketone, trichloromethane, tetrachloromethane, 1,2-dichloroethane, 1,1,1-trichloroethane, n-hexane, cyclohexane, Or more.

About 80 parts by weight to about 99.9 parts by weight of the (meth) acrylic acid ester monomer and about 0.01 to about 10 parts by weight of the functional group-containing monomer. The (meth) acrylate monomer may be at least one selected from the group consisting of methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (Meth) acrylate, isononyl (meth) acrylate, isononyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, Ethylbutyl (meth) acrylate, and combinations thereof.

Also, the functional group-containing monomer may be at least one selected from the group consisting of a hydroxyl group-containing monomer, a carboxyl group-containing monomer, a nitrogen-containing monomer, and combinations thereof. The functional group-containing monomer contained in the mixture means a monomer containing a polar functional group capable of imparting a cohesive force to the solvent-type pressure-sensitive adhesive composition, improving the adhesive strength, providing a polyfunctional crosslinking agent, do.

The specific type of such functional group-containing monomer is not particularly limited, and for example, at least one selected from the group consisting of a carboxyl group-containing monomer, a nitrogen-containing monomer, a hydroxyl group-containing monomer and a combination thereof can be used.

Examples of the carboxyl group-containing monomer include (meth) acrylic acid, acrylic acid diester, fumaric acid, itaconic acid, maleic acid and maleic anhydride; Examples of the nitrogen-containing monomer include (meth) acrylonitrile, (meth) acrylamide, N-methyl (meth) acrylamide, N-methylol (meth) acrylamide, N-vinylpyrrolidone and N- Lactam and the like; Examples of the hydroxyl group-containing monomer include glycerol (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (Meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyleneglycol (meth) acrylate and the like can be given. But is not limited to.

The photopolymerization initiator may be at least one selected from the group consisting of a benzoin compound, a hydroxy ketone compound, an amino ketone compound, a phosphine oxide compound, and a combination thereof. However, It is not particularly limited as long as it can be started.

For example, the photopolymerization initiator may be selected from benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-butyl ether, benzoin isobutyl ether, acetophenone, dimethyl anino acetophenone, 2 , 2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy- Propane-1-one, 4- (2-hydroxyethoxy) phenyl-2- (hydroxy-2- propyl) Ketone, benzophenone, p-phenylbenzophenone, 4,4'-diethylaminobenzophenone, dichlorobenzophenone, 2-methyl anthraquinone, 2-ethyl anthraquinone, 2- Quinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzyldimethylketal, acetophenone dimethylketal, p - dimethylamino benzoate (2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl] propanone] and 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide But is not limited thereto.

The photopolymerization initiator may be about 0.1 part by weight to about 5 parts by weight based on 100 parts by weight of the (meth) acrylate monomer. If the content of the photopolymerization initiator is less than about 0.1 parts by weight, polymerization or curing reaction may not be performed smoothly. If the content is more than about 5 parts by weight, physical properties such as durability and transparency may be deteriorated.

The pressure-sensitive adhesive composition may further include a crosslinking agent together with the acrylic copolymer resin. The crosslinking agent improves the cohesive force of the solvent-type pressure-sensitive adhesive composition through the reaction with the polar functional group contained in the acrylic copolymer resin, imparts a crosslinking structure, and controls the adhesive property.

The type of the crosslinking agent is not particularly limited and a typical crosslinking agent such as a urethane crosslinking agent, an epoxy crosslinking agent, an aziridine crosslinking agent and a metal chelate compound may be used. Among them, a (meth) acrylate ester using an aziridine crosslinking agent It is advantageous in that it can form an effective and quick crosslinking with the functional group of the carboxyl group of the monomer.

Examples of the urethane-based crosslinking agent include at least one selected from the group consisting of toluylene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, and triphenylmethane-4,4 ', 4 "-triisocyanate and the like ; Examples of the epoxy cross-linking agent include ethylene glycol diglycidyl ether, triglycidyl ether, trimethylolpropane triglycidyl ether, N, N, N ', N'-tetraglycidylethylenediamine and glycerin diglycidyl ether ≪ RTI ID = 0.0 > and / or < / RTI > Examples of the aziridine crosslinking agent include N, N'-hexamethylene-1,6-bis (1-aziridine carboxamide) [HDU], N, N'- (2-methyl aziridine) and tri (N, N'-diphenylmethane-4,4'-bis -1-aziridinylphosphine oxide, and the like.

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 to.

The crosslinking agent may be included in an amount of about 0.02 part by weight to about 2.0 parts by weight based on 100 parts by weight of the acrylic copolymer resin. If the content of the crosslinking agent is less than about 0.02 parts by weight, the degree of crosslinking of the pressure-sensitive adhesive resin is weak and the heat-resistant property is deteriorated to make it difficult to use for a long period of time. If more than about 2.0 parts by weight, the degree of crosslinking of the pressure-

In addition, ultraviolet stabilizers, antioxidants, coloring agents, reinforcing agents, fillers, defoamers, surfactants, plasticizers and the like may be appropriately added for specific purposes according to general purposes.

Adhesive film

In another embodiment of the present invention, a substrate; And a pressure-sensitive adhesive layer formed on the base material, wherein the pressure-sensitive adhesive layer comprises an acrylic copolymer resin having a weight average molecular weight of not less than 2,000,000, wherein the acrylic copolymer resin has a molecular weight distribution of not more than 5. [

Examples of the above-mentioned substrate include a polyethylene terephthalate film, a polytetrafluoroethylene film, a polyethylene film, a polypropylene film, a polybutene film, a polybutadiene film, a vinyl chloride copolymer film, a polyurethane film, an ethylene- A copolymer film, an ethylene-ethyl acrylate copolymer film, an ethylene-methyl acrylate copolymer film, or a polyimide film.

The method for forming the pressure-sensitive adhesive layer on the substrate is not particularly limited. For example, after applying the solvent-type pressure-sensitive adhesive composition (coating liquid) by a usual means such as a bar code and performing the coating process, The drying, curing and / or aging process is carried out. At this time, the conditions such as drying can be appropriately selected in consideration of the composition and the like of the coating liquid used.

For example, the drying or curing process may be carried out at a temperature of at least about 100 DEG C for at least about two minutes, and the aging process may be conducted at a temperature of from about 50 DEG C to about 60 DEG C for a period of from about 24 hours to about 72 hours But is not limited thereto.

The thickness of the pressure-sensitive adhesive layer may be about 5 占 퐉 to about 200 占 퐉, specifically, 2 占 퐉 to 12 占 퐉. By maintaining the thickness of the pressure-sensitive adhesive layer within the above-mentioned range, the adhesive force is maintained, and the pressure-sensitive adhesive layer has a constant drying property, which makes it easy to process.

The pressure-sensitive adhesive film containing the pressure-sensitive adhesive layer is excellent in re-peeling property, bending adhesion holding force, peeling force and adhesive force, excellent in cutting property and workability, and can realize stable property at high temperature.

Hereinafter, specific embodiments of the present invention will be described. However, the embodiments described below are only intended to illustrate or explain the present invention, and thus the present invention should not be limited thereto.

< Example  And Comparative Example >

Example  One

90 parts by weight of ethylhexyl acrylate (EHA) and 100 parts by weight of acrylic acid (AA) were added to a 1 L reactor equipped with a cooling device to allow nitrogen gas to be refluxed and easily controlled in temperature, based on the component (100%) of the monomer forming the acrylic copolymer resin. 10 parts by weight of the monomer and ethyl acetate (EAc) as an organic solvent were added and stirred to prepare a mixed solution.

The stirring was continued and the temperature of the mixed solution was raised to 30 DEG C while dissolved oxygen in the mixed solution was removed for 30 minutes. At this time, the temperature of the mixed solution was maintained at 30 ° C., and a photopolymerization initiator prepared by dissolving in a small amount of ethylacetate was added to the reactor to prepare a mixture. Ultraviolet ray of 360 nm wavelength was irradiated to proceed the polymerization reaction. Acrylic copolymer resin was formed.

0.1 part by weight of an aziridine crosslinking agent (HDU, N, N'-hexamethylene-1,6-bis (10 aziridine carboxamide)) was added to 100 parts by weight of the acrylic copolymer resin to prepare a solvent type pressure- . Then, the prepared coating solution was coated on the release treated surface of the release-treated polyethylene terephthalate (PET) film so as to have a thickness of 30 탆. Thereafter, the coating liquid was dried at a temperature of 110 DEG C for 3 minutes, the substrate was laminated, and aged at 50 DEG C for 24 hours to produce an adhesive film comprising a pressure-sensitive adhesive layer having a thickness of 30 mu m.

Example 2

, 72 parts by weight of ethylhexyl acrylate (EHA), 18 parts by weight of methyl acrylate (AA) and 10 parts by weight of acrylic acid (AA) monomer, based on the component (100%) of the monomer forming the acrylic copolymer resin, Ethyl acetate (EAc) was added thereto to prepare a mixed solution, and an acrylic copolymer resin having a molecular weight of 2,100,000 was formed. An adhesive film was prepared in the same manner as in Example 1 above.

Comparative Example 1

The mixture was poured into a 2 L reactor equipped with a reflux condenser and a cooling device so that the temperature could be easily controlled, and the polymerization reaction was carried out by applying heat at 65 DEG C An adhesive film was prepared in the same manner as in Example 1, except that an acrylic copolymer resin having a weight average molecular weight of 1,500,000 was formed.

Comparative Example 2

The mixture was poured into a 2 L reactor equipped with a reflux condenser and a cooling device so that the temperature could be easily controlled, and the polymerization reaction was carried out by applying heat at 65 DEG C An adhesive film was prepared in the same manner as in Example 2 except that an acrylic copolymer resin having a weight average molecular weight of 900,000 was formed.

Comparative Example 3

An adhesive film was prepared in the same manner as in Example 1, except that the acrylic copolymer resin having a weight average molecular weight of 1,500,000 was formed by conducting the polymerization reaction by irradiating the mixture with ultraviolet ray of 360 nm wavelength.

Polymerization method Mw Example 1 Light curing 310 million Example 2 Light curing 2.1 million Comparative Example 1 Thermal polymerization 1.5 million Comparative Example 2 Thermal polymerization 90 million Comparative Example 3 Light curing 1.5 million

< Experimental Example - Physical properties of solvent-type pressure-sensitive adhesive composition

1) Molecular weight distribution: The gel permeation chromatography (Agilient) was used to compare the calibration curve of a polystyrene standard sample with the solvent tetrahydrofuran at a rate of 1.0 min. The molecular weight distribution of the copolymer resin was measured.

2) Peel force (g / in): The above Examples and Comparative Examples were peeled off after 30 minutes, and the peel strength was measured.

3) Shear Stress (kgf / cm ² ): The adhesive films of the above Examples and Comparative Examples were prepared as specimens of 1 X 1 inch (width X length), the specimens were attached to the automobile paint surface, and maintained at 80 캜 for 30 minutes Shear stress was measured at a rate of 1 mm / min.

4) Creep (min): The pressure-sensitive adhesive films of Examples and Comparative Examples were prepared as specimens of 1 X 1 inches (width X length), the pressure-sensitive adhesive films were attached to SUS and hanged at a high temperature of 90 ° C for 1 kg The time for the adhesive film to fall was measured five times and the average value was recorded.

5) Re-peelability: The adhesive films of the examples and comparative examples were attached to the glass surface using a laminator to prepare specimens. The specimens were stored at room temperature for 1 day.

Thereafter, the specimen was stored at 120 ° C for 2 hours, and the pressure-sensitive adhesive film was peeled from the specimen at room temperature. Thereafter, the ratio of the area where the pressure-sensitive adhesive layer remained on the side where the pressure-sensitive adhesive film was adhered was measured to evaluate the re-release property.

&Lt; Criteria for re-

O: When the contaminated area ratio in the above measurement is 4% or less

X: When the contaminated area ratio exceeds 4% in the above measurement

6) Gel fraction (%): The pressure-sensitive adhesive layer formed in the above Examples and Comparative Examples was soaked in ethyl acetate for 1 day, dried at 110 DEG C for 2 hours at 300 mesh, and then measured for gel content.

Molecular weight distribution Peel force
(g / in) Shear stress
(kgf / cm ² ) Creep
(min) Re-peelability
(Percentage of contaminated area) Gel fraction
(%) Example 1 3.4 1740 30 > 10000 O (O) 60 Example 2 3.2 1700 24 > 10000 O (O) 57 Comparative Example 1 10 1500 10 3640 X (4) 59 Comparative Example 2 8 1570 15 4955 X (4) 58 Comparative Example 3 6 1510 14 5350 X (6) 60

As shown in Table 2, the pressure-sensitive adhesive films of Examples 1 and 2 including the acrylic copolymer resin in which the pressure-sensitive adhesive layer was formed by photopolymerization had a smaller molecular weight distribution as compared with Comparative Examples 1 to 3, It was confirmed that the peelability, shear stress and creep were also superior to those of Comparative Examples 1 to 3.

Specifically, the pressure-sensitive adhesive films of Comparative Examples 1 and 2 contain a pressure-sensitive adhesive layer composed of an acrylic copolymer resin formed by thermal polymerization. When the molecular weight distribution exceeds 5, the pressure- 4% or more, and it was found that re-peelability was poor.

The pressure-sensitive adhesive film of Comparative Example 3 contains a pressure-sensitive adhesive layer composed of an acrylic copolymer resin formed by photopolymerization, but the acrylic copolymer resin has a molecular weight of 1.5 million, that is, 2,000,000 or less. Comparative Examples 1 and 2 , It was found that the remnant of the pressure-sensitive adhesive layer remained large and the re-peelability was deteriorated due to a large proportion of the contaminated area.

Claims (15)

And an acrylic copolymer resin having a weight average molecular weight of 2,000,000 or more,
Wherein the acrylic copolymer resin has a molecular weight distribution (Poly Dispersity Index) of 5 or less,
The acrylic copolymer resin is formed by photopolymerizing a mixture of a (meth) acrylic acid ester monomer, a functional group-containing monomer, a photopolymerization initiator and an organic solvent,
The content of the photopolymerization initiator is preferably 1.5 to 5 parts by weight per 100 parts by weight of the (meth) acrylic acid ester monomer
Solvent type pressure-sensitive adhesive composition.
delete The method according to claim 1,
The organic solvent is used in an amount of 10 to 900 parts by weight per 100 parts by weight of the (meth) acrylate monomer
Solvent type pressure-sensitive adhesive composition.
The method according to claim 1,
When the photopolymerization proceeds, the viscosity of the acrylic copolymer resin is from 1,000 cps to 40,000 cps at room temperature
Solvent type pressure-sensitive adhesive composition.
The method according to claim 1,
The organic solvent is selected from the group consisting of ethyl ether, acetone, acetonitrile, petroleum ether, isopropyl alcohol, methanol, ethanol, n-pentane, n-hexane, benzene, dichloromethane, trichloromethane, methyl acetate, ethyl acetate, At least one selected from the group consisting of methyl ethyl ketone, trichloromethane, tetrachloromethane, 1,2-dichloroethane, 1,1,1-trichloroethane, n-hexane, cyclohexane,
Solvent type pressure-sensitive adhesive composition.
The method according to claim 1,
80 to 99.9 parts by weight of the (meth) acrylic acid ester-based monomer and 0.01 to 10 parts by weight of the functional group-containing monomer
Solvent type pressure-sensitive adhesive composition.
The method according to claim 1,
The (meth) acrylate monomer may be at least one selected from the group consisting of methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (Meth) acrylate, isononyl (meth) acrylate, isononyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, Ethylbutyl (meth) acrylate, and combinations thereof.
Solvent type pressure-sensitive adhesive composition.
The method according to claim 1,
Wherein the functional group-containing monomer is at least one selected from the group consisting of a hydroxyl group-containing monomer, a carboxyl group-containing monomer, a nitrogen-containing monomer,
Solvent type pressure-sensitive adhesive composition.
The method according to claim 1,
Wherein the photopolymerization initiator is at least one selected from the group consisting of a benzoin compound, a hydroxy ketone compound, an amino ketone compound, a phosphine oxide compound,
Solvent type pressure-sensitive adhesive composition.
delete The method according to claim 1,
A solvent-based pressure-sensitive adhesive composition further comprising a crosslinking agent.
12. The method of claim 11,
Wherein the crosslinking agent is an aziridine crosslinking agent.
12. The method of claim 11,
The crosslinking agent is contained in an amount of 0.02 to 2.0 parts by weight based on 100 parts by weight of the acrylic copolymer resin
Solvent type pressure-sensitive adhesive composition.
materials; And a pressure-sensitive adhesive layer formed on the substrate and comprising the solvent-type pressure-sensitive adhesive composition according to any one of claims 1 to 13,
Adhesive film.
15. The method of claim 14,
When the thickness of the pressure-sensitive adhesive layer is 5 to 200 占 퐉
Adhesive film.