JP6568864B2 - Method for producing solvent-based pressure-sensitive adhesive composition by photopolymerization - Google Patents

Description

  The present invention relates to a method for producing a solvent-type pressure-sensitive adhesive composition by photopolymerization.

  As a method for producing an acrylic polymer by polymerizing an acrylic monomer, usually, four methods of a solution polymerization method, an emulsion polymerization method, a pearl polymerization method, and a bulk polymerization method are mainly used.

  Among them, the bulk polymerization method uses a peroxide-based or azo-based polymer initiated by heat as a polymerization initiator, so that a certain amount of heat must be supplied into the reaction system in order to cause a polymerization reaction. When the polymerization reaction is caused by the heat energy supplied in this way, there is a problem that the decomposition of the initiator is promoted in a chain by the polymerization heat generated during the polymerization reaction process, and the reaction proceeds explosively. In addition, since there is no dispersion medium that controls the heat of polymerization generated during the reaction, such as a solvent or water, or dissolves or disperses the generated polymer, there is no high volume produced by the polymerization reaction at the initial stage of the polymerization reaction. The molecule exists in a state where the acrylic monomer which has not yet reacted is dissolved in the solvent, but when the polymerization rate increases with time, the acrylic monomer acting as the solvent rapidly decreases. As a result, the viscosity of the polymerization reaction product increases rapidly.

  Therefore, there is an increasing need for an acrylic polymerization method that can solve the problem of explosive reaction progress and high viscosity.

None

  One object of the present invention is to provide a solvent-type pressure-sensitive adhesive composition capable of obtaining a high molecular weight acrylic copolymer resin by irradiating a mixed solution of a polymerization monomer and a polymerization reaction organic solvent with ultraviolet rays. It is in providing the manufacturing method of.

  In one embodiment of the present invention, a step of producing a first mixed solution containing a polymerization monomer and an organic solvent for polymerization reaction, and a photopolymerization initiator is added to the first mixed solution, A method for producing a solvent-type pressure-sensitive adhesive composition, comprising: producing a mixed solution; and irradiating the second mixed solution with ultraviolet rays to initiate a photopolymerization reaction to form an acrylic copolymer resin. I will provide a.

  The acrylic copolymer resin produced by the method for producing the solvent-based pressure-sensitive adhesive composition may have a molecular weight of about 2 million or more and a molecular weight distribution (polydispersity index) of about 5 or less.

  The monomer for polymerization may include a (meth) acrylic acid ester monomer and a functional group-containing monomer.

  The (meth) acrylic acid ester monomers are methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, t-butyl (meth) ) Acrylate, pentyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, 2-ethylbutyl (meth) acrylate, and combinations thereof It can be one or more selected from the group consisting of:

The functional group-containing monomer may be one or more selected from the group consisting of hydroxy group-containing monomers, carboxyl group-containing monomers, nitrogen-containing monomers, and combinations thereof.
The polymerization monomer comprises about 80 parts by weight to about 99.9 parts by weight of the (meth) acrylic acid ester monomer and about 0.01 parts by weight to about 10 parts by weight of the functional group-containing monomer. Can be included.

  The polymerization reaction organic solvent may be included in an amount of about 10 parts by weight to about 900 parts by weight with respect to 100 parts by weight of the polymerization monomer.

  The organic solvent for the polymerization reaction is ethyl ether, acetone, acetonitrile, petroleum ether, isopropyl alcohol, methanol, ethanol, n-pentane, n-hexane, benzene, dichloromethane, trichloromethane, methyl acetate, ethyl acetate, ethylene glycol dimethyl ether, It can be one or more selected from the group consisting of methyl ethyl ketone, trichloromethane, tetrachloromethane, 1,2-dichloroethane, 1,1,1-trichloroethane, n-hexane, cyclohexane, and combinations thereof.

  The photopolymerization initiator may be included in an amount of about 0.1 to about 5 parts by weight with respect to 100 parts by weight of the polymerization monomer.

  The photopolymerization initiator may be one or more selected from the group consisting of benzoin compounds, hydroxyketone compounds, aminoketone compounds, phosphine oxide compounds, and combinations thereof.

  The ultraviolet irradiation may be performed at a wavelength of about 100 nm to about 400 nm.

  The photopolymerization reaction may be performed for about 10 minutes to about 4 hours.

  The method may further include a step of introducing a crosslinking agent into the formed acrylic copolymer resin.

  The crosslinking agent may be an aziridine-based crosslinking agent.

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

  According to the method for producing the solvent-type pressure-sensitive adhesive composition, it is possible to prevent the viscosity from rapidly increasing as the reaction time elapses and to improve the workability during stirring.

  According to the method for producing the solvent-type pressure-sensitive adhesive composition, a rapid and stable polymerization reaction can proceed by irradiation with ultraviolet rays.

  Hereinafter, embodiments of the present invention will be described in detail. However, this is provided by way of example, and is not intended to limit the invention, which is defined by the appended claims.

  In one embodiment of the present invention, a step of producing a first mixed solution containing a polymerization monomer and an organic solvent for polymerization reaction, and a photopolymerization initiator is added to the first mixed solution, A method for producing a solvent-type pressure-sensitive adhesive composition, comprising: producing a mixed solution; and irradiating the second mixed solution with ultraviolet rays to initiate a photopolymerization reaction to form an acrylic copolymer resin. I will provide a.

  In the past, bulk photopolymerization methods were often used to produce acrylic copolymer resins. However, when producing high molecular weight acrylic copolymer resins, a rapid increase in viscosity caused polymerization. There was a problem that stirring and processing sometimes became difficult. Further, in order to overcome the above problems, when using a solution photopolymerization method instead of a bulk photopolymerization method, only a low molecular weight material in an oligomer form having a weight average molecular weight of about 1,000 to about 25,000 is used. Can be manufactured.

  Therefore, according to the method for producing the solvent-type composition, since the conversion rate of the polymerization monomer into the acrylic copolymer resin is high, the acrylic copolymer having a weight average molecular weight of about 2 million or more. Resin can be manufactured. Since photopolymerization can be performed at room temperature compared to general thermal polymerization, the polymerization reaction is easy to control, the reaction time is short, and the productivity is excellent. Therefore, a high molecular weight acrylic copolymer resin is used. Can be manufactured with minimal cost and time.

  The acrylic copolymer resin produced by the method for producing the solvent-type pressure-sensitive adhesive composition may have a molecular weight of 2 million or more and a molecular weight distribution (polydispersity index) of 5 or less. For example, since the acrylic copolymer resin is formed by photopolymerization, in addition to the (meth) acrylic acid ester monomer and the functional group-containing monomer, photopolymerization in which an initiation reaction is caused by light irradiation. Use an initiator. As a result, by performing stable polymerization within a relatively short reaction time of about 2 hours or less at a temperature below room temperature, that is, without artificial heat supply, an acrylic copolymer having a weight average molecular weight of about 2 million or more is used. A polymer resin can be secured.

  The acrylic copolymer resin may have a weight average molecular weight of about 2 million or more. The weight average molecular weight is an average molecular weight obtained by averaging the molecular weights of the component molecular species of the polymer compound having a molecular weight distribution by the weight fraction. For example, the molecular weight of the acrylic copolymer resin is about 200. It can be between 10,000 and 6 million.

  When the acrylic copolymer resin has a weight average molecular weight of about 2 million or more, a solvent-type pressure-sensitive adhesive composition having excellent cutting properties and workability, and having mechanical properties and stable physical properties even at high temperatures should be secured. The application field of the solvent-based pressure-sensitive adhesive composition can be expanded. More specifically, by maintaining the molecular weight at about 2 million to about 4 million, it can have excellent durability even under high temperature and high humidity environment, and easily realize the effect of suppressing white turbidity and bubble generation. be able to. Moreover, reworkability can be improved. Reworkability means that when an adhesive film is used to adhere an optical film or the like to an adherend, if a problem such as contamination of foreign matter occurs, the optical film is peeled off from the adherend to adhere a new film. Means ease of work.

  On the other hand, when the molecular weight is less than about 2 million, sufficient cohesive force in the pressure-sensitive adhesive composition cannot be obtained in a high-temperature and high-humidity environment, which may cause white turbidity and bubbles.

  In addition, the molecular weight distribution of the acrylic copolymer resin may be about 5 or less, specifically about 3.5 or less. Since a normal polymer compound is a mixture of molecular species having different molecular weights, and the molecular weight exhibits polydispersity, the high molecular weight acrylic copolymer resin can have a molecular weight distribution. The molecular weight distribution is a 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, the wider the molecular weight as a whole with the weight average molecular weight as the center, and the smaller the molecular weight distribution means the molecular weight with the weight average molecular weight as the center.

  The wider the molecular weight distribution, the better the workability as the shear stress decreases, but the mechanical strength and durability of the pressure-sensitive adhesive composition decreases, and the thinner the molecular weight distribution, the better the mechanical strength and durability. However, workability may be reduced.

  When the molecular weight distribution is about 5 or less, it is preferable in that not only the mechanical strength and durability of the pressure-sensitive adhesive composition but also the workability can be improved. However, there is a problem that workability may be lowered.

  The monomer for polymerization may include a (meth) acrylic acid ester monomer and a functional group-containing monomer. Specifically, the (meth) acrylic acid ester monomer includes methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, t -Butyl (meth) acrylate, pentyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, 2-ethylbutyl (meth) acrylate, and It can be one or more selected from the group consisting of these combinations.

  The functional group-containing monomer may be one or more selected from the group consisting of a hydroxy group-containing monomer, a carboxyl group-containing monomer, a nitrogen-containing monomer, and combinations thereof. . The functional group-containing monomer contained in the mixture imparts cohesive force to the solvent-type pressure-sensitive adhesive composition and improves adhesive force, and in some cases provides a multifunctional cross-linking agent to provide a cross-linked structure. Means a monomer containing a polar functional group capable of imparting.

  Specific types of such functional group-containing monomers are not particularly limited, and are selected from the group consisting of, for example, carboxyl group-containing monomers, nitrogen-containing monomers, hydroxy group-containing monomers, and combinations thereof. One or more can be used.

  Examples of the carboxyl group-containing monomer include (meth) acrylic acid, acrylic acid dimer, fumaric acid, itaconic acid, maleic acid, maleic anhydride, and the like. Examples include (meth) acrylonitrile, (meth) acrylamide, N-methyl (meth) acrylamide, N-methylol (meth) acrylamide, N-vinyl pyrrolidone, and N-vinyl caprolactam. Examples of monomers include glycerol (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8 -Hydroxyoctyl (meth) acrylate, 2 Hydroxyethylene glycol (meth) acrylate, or 2-like hydroxypropyleneglycol (meth) acrylate including without being limited thereto.

  The polymerization monomer comprises about 80 parts by weight to about 99.9 parts by weight of the (meth) acrylic acid ester monomer and about 0.01 parts by weight to about 10 parts by weight of the functional group-containing monomer. Can be included. When the monomer for polymerization contains the (meth) acrylic acid ester monomer and the functional group-containing monomer in the above range, the pressure-sensitive adhesive composition has excellent adhesive reliability, This is advantageous in that the adhesion reliability at high temperatures is improved.

  The polymerization reaction organic solvent may be included in an amount of about 10 parts by weight to about 900 parts by weight with respect to 100 parts by weight of the polymerization monomer. By including the organic solvent in the above range, the molecular weight increases during the photopolymerization and the viscosity rapidly increases, thereby making it possible to solve the problem that stirring and processing become difficult.

  The kind of the organic solvent for the polymerization reaction is not particularly limited. However, if the drying time of the organic solvent for polymerization reaction is excessively long or if drying at a high temperature is required, problems may occur in terms of workability or durability of the solvent-type pressure-sensitive adhesive composition. It is preferable to use a solvent having a volatilization temperature of about 100 ° C. or lower. In consideration of the moldability of the solvent-type pressure-sensitive adhesive composition, a small amount of an organic solvent for polymerization reaction having a volatilization temperature of the above range or more may be used.

  For example, the organic solvent for polymerization reaction is ethyl ether, acetone, acetonitrile, petroleum ether, isopropyl alcohol, methanol, ethanol, n-pentane, n-hexane, benzene, dichloromethane, trichloromethane, methyl acetate, ethyl acetate, ethylene glycol. It can be one or more selected from the group consisting of dimethyl ether, methyl ethyl ketone, trichloromethane, tetrachloromethane, 1,2-dichloroethane, 1,1,1-trichloroethane, n-hexane, cyclohexane, and combinations thereof .

  The photopolymerization initiator may be included in an amount of about 0.1 to about 5 parts by weight with respect to 100 parts by weight of the polymerization monomer. When the content of the photopolymerization initiator is less than about 0.1 parts by weight, the polymerization or curing reaction may not proceed smoothly, and when it exceeds about 5 parts by weight, durability reliability and transparency There is a risk that the physical properties such as.

  The photopolymerization initiator may be one or more selected from the group consisting of benzoin compounds, hydroxyketone compounds, aminoketone compounds, phosphine oxide compounds, and combinations thereof. If it can generate | occur | produce and start a polymerization reaction, it will not restrict | limit in particular.

  For example, the photopolymerization initiator includes benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2 , 2-Diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4- (methylthio) phenyl] -2 -Morpholino-propan-1-one, 4- (2-hydroxyethoxy) phenyl-2- (hydroxy-2-propyl) ketone, benzophenone, p-phenylbenzophenone, 4,4'-diethylaminoben Phenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-t-butylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethyl Thioxanthone, 2,4-diethylthioxanthone, benzyldimethyl ketal, acetophenone dimethyl ketal, p-dimethylaminobenzoate, oligo [2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl] propanone] , And 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, and the like, but are not limited thereto.

The ultraviolet irradiation may be performed at a wavelength of about 100 nm to about 400 nm. By irradiating ultraviolet rays at a wavelength in the above range, the effect of the initiation reaction can be easily realized during the photopolymerization reaction. Further, the irradiation amount of ultraviolet rays is not particularly limited as long as the physical properties are not impaired and the curing is sufficiently performed. For example, the illuminance is about 50 mW / cm ² to about 1,000 mW / cm ² . There, it is possible amount of about 50 mJ / cm ² ~ about 1,000 mJ / cm ^2.

  The photopolymerization reaction may be performed for about 10 minutes to about 4 hours. When the photopolymerization reaction is performed within the time in the above range, the reaction time is short, and thus the productivity of the pressure-sensitive adhesive composition can be ensured.

  The method for producing the solvent-type pressure-sensitive adhesive composition of the present invention can further include a step of introducing a crosslinking agent into the acrylic copolymer resin formed as described above. The crosslinking agent reacts with the polar functional group contained in the acrylic copolymer resin, thereby improving the cohesive force of the solvent-based pressure-sensitive adhesive composition, imparting a cross-linked structure, and adjusting the adhesive property. Play a role.

  The type of the crosslinking agent is not particularly limited. For example, a general crosslinking agent such as a urethane crosslinking agent, an epoxy crosslinking agent, an aziridine crosslinking agent, and a metal chelate compound can be used, and among them, an aziridine crosslinking agent is used. The use is advantageous in that a cross-linking bond can be formed effectively and rapidly with the carboxy group functional group of the (meth) acrylic acid ester monomer.

  Examples of the urethane-based crosslinking agent include one or more selected from the group consisting of toluylene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, and triphenylmethane-4,4 ′, 4 ″ -triisocyanate. Examples of the epoxy-based crosslinking agent include ethylene glycol diglycidyl ether, triglycidyl ether, trimethylolpropane triglycidyl ether, N, N, N ′, N′-tetraglycidylethylenediamine, and glycerin diglycidyl ether. One or more selected may be mentioned, and examples of aziridine-based crosslinking agents include N, N′-hexamethylene-1,6-bis (1-aziridinecarboxamide) [HDU], N, N′-toluene-2 , 4-Bis (1-aziridine Ruboxamide), N, N′-diphenylmethane-4,4′-bis (1-aziridinecarboxamide), triethylenemelamine, bisisoprotaloyl-1- (2-methylaziridine), and tri-1-aziridinylphosphine One or more selected from the group consisting of oxides can be mentioned.

  Examples of the metal chelate compounds 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. It can be used but is not limited to this.

  The crosslinking agent may be included in an amount of about 0.02 parts by weight to about 2.0 parts by weight with respect to 100 parts by weight of the acrylic copolymer resin. When the content of the crosslinking agent is less than about 0.02 parts by weight, the degree of crosslinking of the adhesive resin is weak and the heat-resistant physical properties are deteriorated. May increase the degree of crosslinking of the pressure-sensitive adhesive resin and prevent basic pressure-sensitive adhesive properties from being obtained.

  In addition, the method for producing the solvent-type pressure-sensitive adhesive composition includes a UV stabilizer, an antioxidant, a toning agent, a reinforcing agent, a filler, an antifoaming agent, a surfactant, and a plasticizer for specific purposes. Etc. may be included as appropriate according to the general purpose.

  Hereinafter, specific examples of the present invention will be presented. However, the examples described below are only for specifically illustrating or explaining the present invention, and the present invention should not be limited thereby.

<Examples and Comparative Examples>
Example 1
Nitrogen gas is refluxed, and a 1 L reactor equipped with a cooling device so that the temperature can be easily adjusted is charged with ethylhexyl acrylate (EHA) based on the monomer component (100%) that forms the acrylic copolymer resin. ) 90 parts by weight, 10 parts by weight of acrylic acid (AA) monomer, and ethyl acetate (EAc) as an organic solvent were added and stirred to prepare a mixed solution.

  The temperature of the mixed solution was raised to 30 ° C. while continuing the stirring and removing dissolved oxygen in the mixed solution for 30 minutes. At this time, after maintaining the temperature of the mixed solution at 30 ° C., a photopolymerization initiator prepared by dissolving in a small amount of ethylacetate is added to the reactor to produce a mixture, and the polymerization reaction is performed by irradiating with ultraviolet light having a wavelength of 360 nm. The acrylic copolymer resin having a weight average molecular weight of 3,100,000 was formed.

  0.1 part by weight of an aziridine-based crosslinking agent (HDU, N, N′-hexamethylene-1,6-bis (10-aziridinecarboxamide)) is blended with 100 parts by weight of the acrylic copolymer resin, A solvent-type pressure-sensitive adhesive composition (coating solution) was produced. Thereafter, the prepared coating solution was coated on the release-treated surface of the release-treated polyethylene terephthalate (PET) film so that the thickness after drying was 30 μm. Next, after drying the coating liquid at a temperature of 110 ° C. for 3 minutes, the substrate was laminated and further aged at a temperature of 50 ° C. for 24 hours to produce an adhesive film including an adhesive layer having a thickness of 30 μm.

(Example 2)
Based on the monomer component (100%) forming the acrylic copolymer resin, 72 parts by weight of ethylhexyl acrylate (EHA), 18 parts by weight of methyl acrylate (MA), 10 parts by weight of acrylic acid (AA) monomer Part, and ethyl acetate (EAc) as an organic solvent was added to produce a mixed solution, and an adhesive film was produced in the same manner as in Example 1 except that an acrylic copolymer resin having a molecular weight of 2.1 million was formed. did.

(Comparative Example 1)
Nitrogen gas is refluxed, and the mixture is put into a 2 L reactor equipped with a cooling device so that the temperature can be easily adjusted, and the polymerization reaction proceeds by applying heat at 65 ° C., so that the weight average molecular weight is 1.5 million. A pressure-sensitive adhesive film was produced in the same manner as in Example 1 except that the acrylic copolymer resin was formed.

(Comparative Example 2)
Nitrogen gas is refluxed, and the mixture is put into a 2 L reactor equipped with a cooling device so that the temperature can be easily adjusted, and the polymerization reaction proceeds by applying heat at 65 ° C., so that the weight average molecular weight is 900,000. An adhesive film was produced in the same manner as in Example 2 except that the acrylic copolymer resin was formed.

(Comparative Example 3)
An adhesive film is produced in the same manner as in Example 1 except that the mixture is irradiated with ultraviolet light having a wavelength of 360 nm to advance the polymerization reaction, thereby forming an acrylic copolymer resin having a weight average molecular weight of 1,500,000. did.

<Experimental Example> -Physical Properties of Solvent Type Adhesive Composition 1) Molecular Weight Distribution: In Gel Permeation Chromatography (Agilent), Tetrahydrofuran was used as the solvent, the speed was 1.0 minute, and polystyrene (polystyrene). The molecular weight distribution of the acrylic copolymer resins of the examples and comparative examples was measured in comparison with a calibration curve of a standard sample.

2) Peeling force (g / in): The adhesive films of Examples and Comparative Examples were attached to the glass surface at a speed of 300 / min, peeled after 30 minutes, and the peeling force was measured.

3) Shear stress (kgf / cm ² ): The adhesive films of the examples and comparative examples were prepared as 1 × 1 inch (width × length) test pieces, and the test pieces were attached to the painted surface of an automobile. After maintaining at a high temperature of 80 ° C. for 30 minutes, the shear stress was measured at a speed of 1 mm / min.

4) Creep (Creep, min): The pressure-sensitive adhesive films of Examples and Comparative Examples were produced as 1 × 1 inch (horizontal × vertical) test pieces. The pressure-sensitive adhesive film was attached to SUS, a 1 kg weight was suspended at a high temperature of 90 ° C., the time for the pressure-sensitive adhesive film to peel was measured five times, and the average value was recorded.

5) Removability: A test piece was prepared by adhering the adhesive films of Examples and Comparative Examples to a glass surface using a laminator, and the test piece was stored at room temperature for 1 day.

  Subsequently, after storing the said test piece at 120 degreeC for 2 hours, the said adhesive film was peeled from the said test piece at normal temperature. Thereafter, the ratio of the area where the pressure-sensitive adhesive layer remained on the surface to which the pressure-sensitive adhesive film was attached was measured, and the removability was evaluated.

<Evaluation criteria for removability>
O: When the ratio of the contaminated area is 4% or less during the measurement X: When the ratio of the contaminated area exceeds 4% during the measurement

6) Gel fraction (%): The pressure-sensitive adhesive layer formed in the above examples and comparative examples was immersed in ethyl acetate for 1 day, then screened with 300 mesh and dried at 110 ° C. for 2 hours, and the weight decreased. The gel content was measured by measuring the degree to which it was done.

Referring to Table 2, the pressure-sensitive adhesive films of Examples 1 and 2 including an acrylic copolymer resin having a pressure-sensitive adhesive layer formed by photopolymerization have a smaller molecular weight distribution than those of Comparative Examples 1 to 3, and are adhesive. Since there was no residue of the agent layer and no contaminated area was generated, it was confirmed that the releasability was excellent and the peeling force, 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 include a pressure-sensitive adhesive layer made of an acrylic copolymer resin formed by thermal polymerization, and the molecular weight distribution exceeds 5, and the pressure-sensitive adhesive layer As a result, it was found that the ratio of the contaminated area was 4% or more and the removability was poor.

The pressure-sensitive adhesive film of Comparative Example 3 includes a pressure-sensitive adhesive layer made of an acrylic copolymer resin formed by photopolymerization, but the molecular weight of the acrylic copolymer resin is 1.5 million, that is, 2 million. In the following cases, as in Comparative Examples 1 and 2, it was found that the residue of the pressure-sensitive adhesive layer was large and the ratio of the contaminated area was wide, so that the removability was poor.

Claims (11)

Producing a first mixed solution comprising a polymerization monomer and a polymerization reaction organic solvent;
Adding a photopolymerization initiator to the first mixed solution to produce a second mixed solution;
Irradiating the second mixed solution with ultraviolet rays to initiate a photopolymerization reaction to form an acrylic copolymer resin;
A method for producing a solvent-type pressure-sensitive adhesive composition comprising a step of adding an aziridine-based crosslinking agent to the formed acrylic copolymer resin ,
The acrylic copolymer resin produced by the method for producing the solvent-type pressure-sensitive adhesive composition has a molecular weight of 2 million or more and 4 million or less, and a molecular weight distribution (polydispersity index) of 5 or less.
The crosslinking agent is included in an amount of 0.02 to 2.0 parts by weight with respect to 100 parts by weight of the acrylic copolymer resin.
A method for producing a solvent-type pressure-sensitive adhesive composition.   The said polymerization monomer is a manufacturing method of the solvent-type adhesive composition of Claim 1 containing a (meth) acrylic acid ester monomer and a functional group containing monomer.   The (meth) acrylic acid ester monomer is methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, t-butyl (meth) ) Acrylate, pentyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, 2-ethylbutyl (meth) acrylate, and combinations thereof The manufacturing method of the solvent-type adhesive composition of Claim 2 which is one or more selected from the group which consists of.   The functional group-containing monomer is one selected from the group consisting of a hydroxy group-containing monomer, a carboxyl group-containing monomer, a nitrogen-containing monomer, and a combination thereof. A method for producing a solvent-type pressure-sensitive adhesive composition.   The polymerization monomer includes 80 parts by weight to 99.9 parts by weight of the (meth) acrylic acid ester monomer and 0.01 parts by weight to 10 parts by weight of the functional group-containing monomer. 2. A process for producing the solvent-type pressure-sensitive adhesive composition according to 2.   The method for producing a solvent-type pressure-sensitive adhesive composition according to claim 1, wherein the organic solvent for polymerization reaction is contained in an amount of 10 to 900 parts by weight with respect to 100 parts by weight of the monomer for polymerization. The organic solvent for the polymerization reaction is ethyl ether, acetone, acetonitrile, petroleum ether, isopropyl alcohol, methanol, ethanol, n-pentane, n-hexane, benzene, dichloromethane, trichloromethane, methyl acetate, ethyl acetate, ethylene glycol dimethyl ether, 2. One selected from the group consisting of methyl ethyl ketone, trichloromethane, tetrachloromethane, 1,2-dichloroethane, 1,1,1-trichloroethane, n-hexane, cyclohexane, and combinations thereof. A method for producing a solvent-type pressure-sensitive adhesive composition.   The said photoinitiator is a manufacturing method of the solvent-type adhesive composition of Claim 1 contained by 0.1 weight part-5 weight part with respect to 100 weight part of said monomers for polymerization.   The solvent-type adhesive according to claim 1, wherein the photopolymerization initiator is one selected from the group consisting of a benzoin compound, a hydroxyketone compound, an aminoketone compound, a phosphine oxide compound, and a combination thereof. A method for producing an agent composition.   The said ultraviolet irradiation is a manufacturing method of the solvent-type adhesive composition of Claim 1 performed by the wavelength of 100 nm-400 nm.   The method for producing a solvent-type pressure-sensitive adhesive composition according to claim 1, wherein the photopolymerization reaction is performed for 10 minutes to 4 hours.