JPH0384011A - Production of photopolymerizable composition and adhesive mass - Google Patents

Abstract

PURPOSE:To obtain the subject composition giving adhesive mass having excellent balance of physical properties such as tack strength and retentive strength with photopolymerization containing specific monomer component, photopolymerization initiator, crosslinkable monomer and chain transfer agent in a specific ratio. CONSTITUTION:The objective composition contains (A) 100 pts.wt. monomer component containing 60-100wt.% alkyl (meth)acrylate having 1-12C alkyl group and 0-40wt.% vinyl-based monomer [e.g. (meth)acrylic acid] copolymerizable with said acrylate-based monomer, (B) 0.001-5 pts.wt. photopolymerization initiator [e.g. 4-(2-hydroxyethoxy) phenyl (2-hydroxy-2-propylketone], (C) 0.01-2 pts.wt. crosslinkable monomer copolymerizable with acrylate-based monomer having >=2 unsaturated double bonds in a molecule [e.g. hexanediol di(meth)acrylate] and 0.01-2 pts.wt. chain transfer agent (e.g. butylmercaptane).

Description

[Detailed description of the invention]

[Industrial Application Field 1] The present invention relates to an acrylate-based photopolymerizable composition, and more specifically, to provide a pressure-sensitive adhesive with well-balanced physical properties such as adhesive strength and holding power with good productivity through photopolymerization. The present invention relates to a photopolymerizable composition that can be used as a photopolymerizable composition. The present invention also relates to a method for producing an adhesive from the photopolymerizable composition and an adhesive (adhesive product). [Conventional technology] Acrylic adhesives have acrylic polymer as their main component, so they have excellent light resistance, weather resistance, oil resistance, etc. Acrylic adhesive tapes with surface base materials such as plastic film or paper is adhesive performance such as adhesive strength and cohesive strength,
It is widely used because it has excellent aging resistance such as heat resistance and weather resistance. Taking acrylic adhesive tape as an example, which is a typical acrylic adhesive product, -M contains a vinyl monomer whose main component is an acrylate monomer such as an acrylic acid alkyl ester and/or a methacrylic acid ester. It is manufactured by coating or impregnating a base material with an adhesive solution obtained by solution polymerization in an organic solvent system or an emulsion obtained by emulsion polymerization in an aqueous system, and then heating and drying this. In the above manufacturing method, when using an adhesive solution,
A large amount of energy is required to dry the adhesive solution applied or impregnated onto the substrate at high temperatures, and a large-scale solvent recovery device is required to prevent air pollution caused by the solvent. Moreover, since the solvent is easily flammable, sufficient safety equipment is required to maintain safety. On the other hand, when an emulsion is used, more energy is required to evaporate water than when a solvent is used, and in terms of performance, water resistance is reduced due to the emulsifier mixed in during polymerization. Furthermore, since water-soluble monomers cannot be used, the type of monomer is limited, and there is a drawback that the ability to respond to the wide variety of needs required for adhesive tapes is weak. Therefore, a photopolymerization method has been proposed as a method for producing adhesive products without using solvents. For example, in Verigy Patent No. 675.420,
A method is disclosed in which a monomer is applied to a substrate and then directly polymerized by UV irradiation. Furthermore, US Pat. No. 4,181,752 discloses a solvent-free photopolymerizable liquid composition containing a photoinitiator such as benzoin ethyl ether in a vinyl monomer mainly composed of an acrylate monomer. This composition was exposed to ultraviolet rays with a wavelength of 300 to 400 nm at a wavelength of 0.1 to 7 m.
W/crr? A method for producing an acrylic pressure-sensitive adhesive tape is disclosed by polymerizing the above-mentioned vinyl monomer by irradiating it with a light intensity of . These methods increase the molecular weight of the polymer using the vinyl monomer by lowering the intensity of ultraviolet rays, thereby improving adhesive properties such as adhesive force and cohesive force. According to this method, adhesive tapes can be manufactured without using solvents, so the problems associated with the use of organic solvents and water described above are solved. However, this method has the drawback that the polymerization reaction rate is slow and the productivity is too low for practical use. By the way, in general, in the photopolymerization of vinyl monomers such as acrylate monomers, the polymerization reaction rate is proportional to the square root of the product of the amount of photoinitiator and the light intensity. Therefore, in order to increase productivity, increasing the amount of photoinitiator added or increasing the light intensity to accelerate the polymerization reaction rate.
The molecular weight of the obtained polymer decreases, and the balance between adhesive strength and cohesive strength of the adhesive tape cannot be maintained at a high level. Therefore, in order to actually produce adhesive tapes using the photopolymerization method, it is necessary to make the light irradiation zone extremely long or to slow down the line speed, which results in huge equipment costs and production costs. There are problems such as low efficiency, making it difficult to put it into practical use. Radcure '86 (BaLtimore) Abstracts P, 12-29 describes the use of composites of thermoplastic polymers and monomers in order to simultaneously satisfy productivity and adhesive performance in the production of adhesive tapes by photopolymerization.
It has been reported that there are research examples of composites of reactive polymers and monomers, and composites of hot-melt rubber and polyfunctional monomers. However, sufficient results for practical use have not been reported. Further, Japanese Patent Publication No. 60-28318 discloses a photocurable adhesive composition comprising a prepolymer having a (meth)acryloyl group in the molecule and a specific chain transfer agent. This method uses a low polymer such as (meth)acrylic acid ester in which one or more reactive (meth)acryloyl groups are introduced into the terminal or side chain. ) Requires complicated steps such as introduction of acryloyl groups. As described above, the conventional pressure-sensitive adhesive manufacturing technology using photopolymerization is still insufficient in terms of simultaneously maintaining high levels of adhesive performance and productivity. [Problems to be Solved by the Invention] The object of the present invention is to provide a novel method for producing an acrylic adhesive that maintains high levels of adhesive performance and productivity in a method of producing an adhesive using a photopolymerization method. An object of the present invention is to provide a photopolymerizable composition. Another object of the present invention is to provide a method for producing an adhesive by a photopolymerization method using the photopolymerizable composition and an adhesive. (Note that in the present invention, the term "adhesive" is used to include adhesive products such as adhesive tapes.) First, the present inventor developed a method that consists of a monomer component containing an acrylate monomer as a main component and a photoinitiator. When a crosslinkable monomer having two or more unsaturated double bonds in one molecule was added to the composition and irradiated with light, a crosslinked polymer could be obtained. However, when photopolymerization is carried out by adjusting the light intensity and the amount of photoinitiator added in order to carry out photopolymerization at a reaction rate suitable for practical use (high-speed reaction), only polymers with short polymer main chain lengths can be obtained. However, crosslinking using a crosslinking monomer only provided a partially crosslinked product, and high performance adhesive properties could not be obtained. Therefore, when a chain transfer agent was further added and photopolymerization was performed under high-speed reaction conditions, it was discovered that a high-performance adhesive could be obtained. Chain transfer agents are usually used as polymerization degree regulators and have the function of lowering the molecular weight. Therefore, when a chain transfer agent is added to a composition containing the crosslinking monomer, the molecular weight can be further reduced. It was thought that this would cause performance deterioration. Therefore, it was unexpected that a high-performance adhesive could be obtained by photopolymerization by combining a crosslinking monomer and a chain transfer agent. The present invention has been completed based on these findings.

[Means to solve the problem]

Thus, according to the present invention, (a) 6O-100% by weight of at least one acrylate monomer selected from the group consisting of acrylic acid alkyl esters and methacrylic acid alkyl esters having an alkyl group having 1 to 12 carbon atoms; 100 parts by weight of a monomer component containing 0 to 40% by weight of a vinyl monomer copolymerizable with the acrylate monomer, (b) 0.001 to 5 parts by weight of a photoinitiator, (c) two or more in one molecule. 0.01 to 2 crosslinkable monomers having unsaturated double bonds and copolymerizable with acrylate monomers
and (d) 0.01 to 2 parts by weight of a chain transfer agent. Further, according to the present invention, there is provided a method for producing an adhesive, characterized in that the photopolymerizable composition is irradiated with light to copolymerize the monomer component and the crosslinkable monomer, and Adhesives (adhesive products) are provided. Hereinafter, the constituent elements of the present invention will be explained in detail. (Monomer component) The monomer component used in the present invention is at least one acrylate monomer selected from the group consisting of acrylic acid alkyl esters and methacrylic acid alkyl esters having an alkyl group having 1 to 12 carbon atoms.
% by weight and 0 to 40% by weight of a vinyl monomer copolymerizable with the acrylate monomer. Acrylate monomers As acrylate monomers, acrylic acid alkyl esters or methacrylic acid alkyl esters in which the alkyl group has 1 to 14 carbon atoms, preferably 4 to 12 carbon atoms, are used. Specific examples include (meth)acrylic acid n- butyl,
2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate,
Examples include isobornyl (meth)acrylate. Acrylate monomers that form polymers with a low glass transition temperature, such as tetrahydrofurfuryl acrylate, polyethylene glycol acrylate, polybrobylene glycol acrylate, fluorine acrylate, and silicone acrylate, can also be used. These are used alone or in combination of two or more. Considering the balance between adhesiveness and cohesiveness, the main component is usually an acrylic acid alkyl ester with a homopolymer glass transition temperature of 150°C or less, and as a comonomer, a (meth)allylic acid ester of a lower alkyl group or the following vinyl ester is used as a comonomer. It is preferable to use monomers based on the monomers. Other vinyl monomers that can be copolymerized with the acrylate monomer include, for example, acrylic acid, methacrylic acid, acrylamide, acrylonitrile, methacrylate trile, N-substituted acrylamide, hydroxyethyl acrylate, Examples include N-vinylpyrrolidone, maleic acid, itaconic acid, N-methylolacrylamide, and hydroxyethyl methacrylate. These vinyl monomers can be used singly or in combination of two or more, but if the proportion of these vinyl monomers exceeds 40% by weight in the total monomer components, the adhesive properties of the acrylic adhesive will deteriorate. Undesirable. (Photoinitiator) As a photoinitiator, any ordinary photoinitiator used in the fields of UV-curable inks and paints can be used, but in order to sufficiently complete the photopolymerization reaction, so-called A cleavage type is preferable to a hydrogen abstraction type, and a type having high photo-cold activity and less inhibition of activity by oxygen is preferable. Specific examples of the photoinitiator include, for example, 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2-propylketone [Dalochea-2959: manufactured by Merck & Co., Ltd.];
-Hydroxymethyl-1-phenylpropan-1-one [Tarocur 11F3: manufactured by Mel 2]; Acetophenone series such as methoxyacetophenone and 2,2-dimethoxy-2-phenylacetophenone; Benzoin ethyl ether, benzoin isopropyl ether, etc. benzoin ether type; ketal type such as benzyl dimethyl ketal; other examples include acyl oxime esters, halogenated ketones, hydroxyalkylstyrene oligomers, acylphosphine oxides, and acyl phosphonates. (Crosslinking properties) The crosslinking monomer used in the present invention has two or more unsaturated double bonds in one molecule, such as epoxy acrylate, urethane acrylate, and polyester acrylate. Specific examples of crosslinkable monomers include hexanediol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, and neobentyl glycol di(meth)acrylate. , pentaerythritol di(meth)acrylate, trimethylolpropane tri(
Examples include meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, epoxy acrylate, polyester acrylate 1, and urethane acrylate. When the crosslinkable monomer is contained in an amount of 0.01 to 2 parts by weight based on 100 parts by weight of the monomer components, crosslinking bonds are generated between polymer molecules during the photopolymerization reaction, and the adhesive (adhesive product) is Improves heat resistance. In addition, the crosslinking monomer and the chain transfer agent work together to produce an adhesive with excellent adhesive strength and retention even when photopolymerization is carried out at a reaction rate commensurate with practical use (high-speed reaction). . If the blending ratio of the crosslinkable monomer is too small, the holding power tends to decrease, and if it is too large, the adhesive strength and the holding power tend to decrease. (Chain transfer agent) The chain transfer agent used in the present invention has 1 chain transfer agent in the molecule.
Those having at least one thiol group or disulfide group are preferred. Specific examples of chain transfer agents include alkyl mercaptans such as butyl mercaptan and lauryl mercaptan; thioglycolic acid, thioglycolic acid alkyl ester, ethylene glycol dithioglycolate, pentaerythritol tetrakis thioglycolate, mercaptopropionic acid; Mercapropropionate ester, 1
．． 4-butanediol dithioprobionate, pentaerythritol tetrakisthioprobionate, furfuryl mercaptan, 4-aminothiophenol, stearyl mercaptan, 3-mercapto-2-methylpropionic acid, 2-mercaptoethyl octanoate, 3.
Examples include 3'-dithiodipropionic acid, tert-butyl disulfide, diphenyl sulfide, benzyl disulfide, furfuryl disulfide, cystamate, and the like. The chain transfer agent is used in an amount of 0.0% per 100 parts by weight of the monomer components.
It is used in a proportion of 0.01 to 2 parts by weight. If the blending ratio of the chain transfer agent is too small or too large, it is difficult to obtain a pressure-sensitive adhesive with a well-balanced adhesive force and holding force. (Other Additives) In the present invention, commonly used additives such as thickeners, thixotropic agents, extenders, and fillers may be added to the photopolymerizable composition. Examples of thickeners include acrylic rubber, epichlorohydrin rubber, and natural rubber. Thixotropic agents include colloidal silica and polyvinylpyrrolidone. Extending agents include calcium carbonate, titanium oxide, and clay. Fillers include inorganic hollow bodies such as glass balloons, alumina balloons, and ceramic balloons; organic spherical bodies such as nylon beads, acrylic beads, and silicon beads; organic hollow bodies such as vinylidene chloride balloons and acrylic balloons; polyester, rayon, nylon, etc. short fibers; etc. (Adhesive and method for producing the same) The photopolymerizable composition of the present invention can be used as an adhesive by photopolymerizing, for example, adhesive tapes, heat-sensitive adhesive sheets, sealing materials for buildings and automobiles, and protective materials. It is useful for manufacturing various adhesive products such as vibration materials. When producing an adhesive (adhesive product) using the photopolymerizable composition of the present invention, the composition is usually purged with an inert gas such as nitrogen gas to remove oxygen dissolved in the composition. Alternatively, a compound capable of removing oxygen such as phenyl diisodecyl phosphite, triisodecyl phosbutite, and stannous octoate is added. By adding a compound capable of removing oxygen, sufficient polymerization (curing) can be achieved even if the oxygen concentration in the atmosphere is high to some extent. For example, when manufacturing adhesive tape,
The photopolymerizable composition is coated or injected onto release paper, release molds, etc., or coated or impregnated onto substrates such as plastic films, paper, cellophane, cloth, non-woven fabrics, metal foils, etc. In the former case, an adhesive tape without a base material is obtained. When producing a sealant as an adhesive product, a photopolymerizable composition is poured into a peelable elongated mold or the like. When applying, impregnating, or injecting the photopolymerizable composition onto a mold, a substrate, etc., it is preferable to thicken it with a thickener or thixotropic agent so that the work can be carried out smoothly. Another method for increasing the viscosity is to irradiate a small amount of ultraviolet rays to polymerize a portion of the monomer components in advance. This partial polymerization by light requires purging the reaction vessel with an inert gas, but the polymerization can be easily started in a short time by light irradiation, and the reaction can be stopped when the irradiation is stopped. syrup) can be easily thickened to the desired viscosity. Furthermore, when manufacturing double-sided adhesive tapes, conventional adhesives have relatively high viscosity, making it difficult to impregnate them into the base material, but the photoreactive composition of the present invention has a low viscosity. Since it is a reactive syrup, it can be easily impregnated into a base material, and it can also be made into an adhesive tape by irradiating light from one side. Therefore, the photopolymerizable composition of the present invention is suitable for producing double-sided pressure-sensitive adhesive tapes. For these coating, impregnation, or injection operations, equipment designed to avoid contact with air (oxygen) is used. After coating, impregnating, or injecting the photopolymerizable composition onto a mold or base material, the photopolymerizable composition is passed through a box purged with an inert gas and exposed to ultraviolet light or Irradiation with light such as visible light is performed. In addition, even if it is not in an inert gas atmosphere, the surface of the photopolymerizable composition applied, impregnated, or injected onto a mold or substrate can be covered with a light-transmitting film such as a polyester film that has mold releasability. In this way, light irradiation may be performed while preventing contact with air (oxygen). In this case, it is preferable to add a compound capable of removing oxygen. As the light, ultraviolet rays are usually used. As an ultraviolet lamp, one having a spectral distribution in the wavelength range of 300 to 400 nm is usually used, but specific examples include:
There are chemical lamps, black light lamps (trade name of Toshiba Denzai ■), low-pressure, high-pressure, and ultra-high-pressure mercury lamps, metal halide lamps, and microwave-excited mercury lamps. The first two lamps are used to obtain a relatively low light intensity, and the last two lamps are used to obtain a relatively high light intensity. Conventionally, when it was desired to obtain a polymer with a high molecular weight, irradiation with a relatively low-intensity lamp was required for a long time, but with the photopolymerizable composition of the present invention, it can be obtained by irradiation with a high-intensity lamp for a short time. Since high molecular weight can also be obtained, from the viewpoint of productivity,
Preferably, high intensity lamps are used. The light intensity can be adjusted by adjusting the distance to the irradiated object and the voltage.
Generally, it is about 5 to 300 mW/crrf, and the irradiation time is about 0.3 to 5 minutes. Irradiation with light such as ultraviolet rays causes copolymerization of a monomer component containing an acrylate monomer as a main component and a crosslinkable monomer to obtain an adhesive (adhesive product). Note that the light irradiation may be performed at a constant light intensity, but
By dividing the irradiation into two or more stages and changing the light intensity in each stage, the physical properties of the adhesive can be adjusted more precisely. [Function l] If only a crosslinking monomer is added to a composition consisting of a monomer component mainly composed of acrylate monomers and a photoinitiator, the resulting polymer will not be produced when photopolymerization is carried out under high-speed reaction conditions suitable for commercial production. The main chain length of is shortened, and only a partially crosslinked product is obtained. However, when a chain transfer agent is added to a composition that contains a monomer component, a photoinitiator, and a crosslinkable monomer and produces a highly crosslinked product with a gel fraction of 30 to 100% under appropriate light irradiation conditions, Polymers with excellent adhesive properties can be produced. In a region where the amount of crosslinking monomer is too small, addition of a chain transfer agent has the opposite effect and it is not possible to obtain a pressure-sensitive adhesive with high performance. The effect of the combined use of a crosslinking monomer and a chain transfer agent in the present invention is surprising, since chain transfer agents were generally thought to reduce the degree of polymerization. [Example J Hereinafter, the present invention will be specifically explained by giving Examples and Comparative Examples, but the present invention is not limited only to these Examples. <Evaluation of physical properties> Tape 1 Regarding the double-sided pressure-sensitive adhesive tapes obtained in Examples or Comparative Examples, the adhesive force and holding force, the weight average molecular weight, and the amount of residual monomer were measured by the following measuring method. (1) Adhesive strength Paste a 25 μm thick polyester film on one side of double-sided adhesive tape to make an adhesive tape with a width of 25 mm and a length of 300 mm, and then place the tape on a steel plate polished with #280 sandpaper. Length 100-120m from one end
Paste the m part by moving it back and forth once with a 2 kg roller, 3
After aging for 0 minutes, the other end of the tape was tested at 300°C using an Instron tensile tester at 23°C and 65% RH.
It was peeled off in the opposite direction at a 180 degree angle at a speed of mm/min, the resistance force at that time was measured using a tensile tester, and the adhesive force (g/25m
m width). (2) Holding power Paste 100 μm thick aluminum foil on one side of double-sided adhesive tape to make an adhesive tape with a width of 25 mm.
Paste one end of the tape on a steel plate polished with 280-grit sandpaper by moving it back and forth once with a 2 kg roller so that the adhesive area is 25 mm in width and 25 mm in length.
Fix a 1 kg weight to the other end of this tape and
The tape was hung at an ambient temperature of 0.degree. C., and the time until the weight dropped together with the tape was measured, and the holding force (time) was determined. (3) Weight average molecular weight gel permeation chromatography (GPC)
was measured using standard polystyrene as a reference. Tetrahydrofuran was used as the eluent at a flow rate of 1 m12/min.
Detection was by refractometer. Note that the weight average molecular weight was measured only when no crosslinking monomer was added. (4) Residual monomer amount Polyethylene glycol (Product name 2 manufactured by Gascro Kogyo Co., Ltd.)
The measurement was performed using a gas chromatograph (GC-6A; manufactured by Noho Seisakusho) equipped with a separation column in which chromosorb-w carrying 0M) was treated with an acid and a hydrogen flame ion detector. The measurement sample was obtained by collecting 2 cc of a solution of 100 mg of the adhesive sample dissolved in 5 cc of methyl acetate, and mixing 2 cc of this solution with 2 cc of an internal standard solution in which 2-ethylhexyl methacrylate was dissolved in methyl acetate. Prepared. [Examples 1 to 5] To 100 parts by weight of a monomer component consisting of 97% by weight of 2-ethylhexyl acrylate and 3% by weight of acrylic acid,
1 part by weight of benzyl dimethyl ketal was added as a photoinitiator, hexanediol diacrylate was added as a crosslinking monomer, and lauryl mercaptan was added as a chain transfer agent in the proportions shown in Table 1, and the mixture was stirred with a stirrer. A photopolymerizable composition was prepared by stirring to mix uniformly. The resulting photopolymerizable composition is purged with nitrogen gas to remove dissolved oxygen, and then impregnated into a nylon nonwoven fabric on a transparent polyester film treated with a release agent, the surface of which is covered with the same film as above, This was passed through the squeezing roll of the applicator to make the thickness uniform. Next, an ultra-high pressure mercury lamp (manufactured by Oak Co., Ltd., JetCure JL-
1300) at a light intensity of 25 mW/crrr (wavelength centered at 365 nm) for 60 seconds. The amount of residual monomer was 0.05% or less. In this way, the film thickness is 2201. A double-sided adhesive tape of Lm was manufactured. The measurement results of physical properties are shown in Table 1. As is clear from Table 1, when the photopolymerizable composition of the present invention is used, it is possible to produce adhesive tapes with highly balanced adhesive strength and holding power by light irradiation at high light intensity and for a short period of 60 seconds. It can be seen that the following results can be obtained. (Left below) [Comparative Example 1] Photopolymerizable product in which 1 part by weight of benzyl dimethyl ketal as a photoinitiator was added to 100 parts by weight of a monomer component consisting of 97% by weight of 2-ethylhexyl acrylate and 3% by weight of acrylic acid. Double-sided pressure-sensitive adhesive tapes were prepared in the same manner as in Examples 1 to 5, except that the composition was used and no crosslinking agent and chain transfer agent were added. The weight average molecular weight of the obtained adhesive was 194,000, and the amount of residual monomer was 0.
The adhesive strength of double-sided adhesive tape, which was 0.05% or less, was 13.
00g/25mm width, but the holding force (40°C) was
It took less than 0.1 hour and could not be used as a normal adhesive tape. [Comparative Examples 2 to 6] In the photopolymerizable composition, 0.05.0% of hexanediol diacrylate was added as a crosslinking monomer, respectively.
．． A double-sided adhesive tape was prepared in the same manner as in Comparative Example 1, except that 0.07.0.2.0.5 parts by weight of the tape was added. The results are shown in Table 2. Table 2 shows that when a crosslinking monomer is not used (Comparative Example 1), only an adhesive tape with low holding power is obtained, and even when a crosslinking monomer is used, a chain transfer agent is not used together. It can be seen that the holding force is low, and as the blending ratio of the crosslinking monomer increases, the adhesive force also decreases significantly. Effects of the Invention 1 According to the present invention, even with high light intensity and short-time irradiation, a photopolymerization method can be used to produce an adhesive product that has well-balanced physical properties necessary for an adhesive, such as adhesive strength and holding power. can be manufactured. In addition, the irradiation zone can be shortened, and there is no need to use or recover solvents, so equipment costs and production costs can be reduced. Furthermore, since products with a thick film can be manufactured by one-time coating and light irradiation, it is possible to manufacture products with high performance and functionality in a short time.

Claims (3)

[Claims] (1) (a) 60 to 100% by weight of at least one acrylate monomer selected from the group consisting of acrylic acid alkyl esters and methacrylic acid alkyl esters having an alkyl group having 1 to 12 carbon atoms; Copolymerizable vinyl monomer 0~
(b) 0.001 to 5 parts by weight of a photoinitiator; (c) having two or more unsaturated double bonds in one molecule and coexisting with an acrylate monomer; 0 polymerizable crosslinking monomers
．． 0.01 to 2 parts by weight, and (d) 0.01 to 2 parts by weight of a chain transfer agent. (2) irradiating the photopolymerizable composition according to claim 1 with light,
A method for producing an adhesive, comprising copolymerizing the monomer component and a crosslinking monomer. (3) An adhesive obtained by the manufacturing method according to claim 2.