JP2016029129A - Adhesive composition and adhesive film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an adhesive composition and an adhesive film which are low in elasticity and dielectric constant, show excellent properties as adhesives, and also have excellent film strength and adhesion, by using specific block polymers.SOLUTION: An adhesive composition comprises a block polymer, which is an acryl polymer made by polymerization of polymerizable monomers of three or more components, the block polymer comprising a first polymer unit comprising a structure derived from a first polymerizable monomer having a hydroxy group and a structure derived from a second polymerizable monomer, and a second polymer unit comprising a structure derived from the first polymerizable monomer having a hydroxy group and a structure derived from a third polymerizable monomer different from the second polymerizable monomer. There is also provided an adhesive film prepared with the composition.SELECTED DRAWING: None

Description

  The present invention relates to an adhesive composition and an adhesive film that contain a hydroxyl group-containing acrylic block polymer obtained by polymerizing monomers of three or more components as components and can be usually used as a curable adhesive.

  Acrylic polymers can be easily produced by radical polymerization of acrylic monomers, and the properties of the resin can be widely changed by copolymerizing several types of acrylic monomers depending on the purpose. Widely manufactured industrially. Moreover, bulk polymerization, solution polymerization, suspension polymerization and the like are widely used as the production method, and are selected in view of the molecular weight and cost of the acrylic polymer to be produced. Conventional acrylic polymers are generally produced by free radical polymerization, so acrylic polymers obtained from multi-component monomers are random copolymers and have a broad molecular weight distribution.

  Acrylic polymers can exhibit characteristics such as transparency, adhesiveness, low elasticity, and high hardness by selecting monomer types, and are being developed in the fields of optics, electronic materials, and structural materials. Moreover, it is possible to incorporate a thermosetting reaction by copolymerizing a monomer containing a hydroxyl group as its component, or to incorporate photoreactivity by introducing a photoreactive group, which is used as an adhesive or an adhesive film. It is possible.

  In recent years, various living radical polymerizations capable of controlling the structure of block polymers, graft polymers, star polymers and the like have been developed in order to realize high performance and high functionality of acrylic polymers. Reversible addition-fragmentation chain transfer (RAFT) polymerization has been developed as a living radical polymerization method as a method for synthesizing acrylic polymers. RAFT polymerization takes the behavior of living polymerization by using a chain transfer agent having a thiocarbonate structure to cause reversible addition cleavage at the polymer growth terminal and causing chain transfer to a monomer. RAFT polymerization can polymerize acrylic acid and methacrylic acid without protecting groups, and enables copolymerization with various acrylic esters, methacrylic esters, styrene, etc. (see Patent Documents 1 and 2). ).

Special Table 2000-515181 JP 2010-59231 A

  The present invention uses a multi-component block polymer having three or more components in which the physical properties of the polymer due to a specific polymerizable monomer are not changed by the sequence of the polymer and the block property of other polymerizable monomers is increased. It is an object of the present invention to obtain a highly functional adhesive composition and adhesive film that make use of the characteristics.

  Above all, in block polymers having a hydroxyl group-derived structural unit, the structural units of other polymerizable monomers can be blocked, so that the film strength and adhesiveness do not decrease even if the dielectric constant is lowered or the elastic modulus is lowered. An object is to obtain an adhesive composition and an adhesive film having the following formula.

  The present invention is an acrylic polymer obtained by polymerizing a polymerizable monomer having three or more components, and includes a structure derived from a first polymerizable monomer having a hydroxyl group and a structure derived from a second polymerizable monomer. Containing a block polymer having a second polymer unit comprising a polymer unit and a structure derived from a first polymerizable monomer having a hydroxyl group and a structure derived from a third polymerizable monomer different from the second polymerizable monomer. It is related with the adhesive composition formed.

The present invention also relates to the above adhesive composition, wherein the second polymerizable monomer is an acrylic ester or a methacrylic ester.
The present invention also relates to the above adhesive composition, wherein the third polymerizable monomer is an acrylic ester or methacrylic ester different from the second polymerizable monomer.

The present invention also relates to the above adhesive composition, wherein the third polymerizable monomer has a lower dielectric constant than the second polymerizable monomer.
Moreover, this invention relates to the said adhesive composition whose weight average molecular weights of a block polymer are 10,000-500,000.

Moreover, this invention relates to the said adhesive composition whose molecular weight dispersion degree of a block polymer is 1.2-4.0.
Furthermore, this invention relates to the adhesive film formed in a film form using the adhesive composition in any one of the above.

  By using a specific block polymer, the adhesive composition and adhesive film of the present invention have low elasticity and low dielectric constant, and exhibit good properties as an adhesive. It is good.

  The block polymer used in the present invention is an acrylic polymer obtained by polymerizing a polymerizable monomer having three or more components, and has a structure derived from the first polymerizable monomer having a hydroxyl group and a structure derived from the second polymerizable monomer. The second polymer unit includes a structure derived from a third polymerizable monomer different from the structure derived from the first polymerizable monomer having a hydroxyl group and the first polymerizable monomer having a hydroxyl group.

This block polymer preferably has a first polymer unit as a block and a second polymer unit as a block at one or both ends thereof.
The first polymerizable monomer is preferably a block polymer which is an acrylic ester having a hydroxyl group or a methacrylic ester having a hydroxyl group, and the second polymerizable monomer is an acrylic ester or hydroxyl group having no hydroxyl group. More preferably, the third polymerizable monomer is an acrylate ester having no hydroxyl group or a methacrylate ester having no hydroxyl group different from the second polymerizable monomer. More preferably.

Although the molecular weight is not particularly limited, those having a weight average molecular weight of 10,000 to 500,000 are preferable, and those having a molecular weight dispersity of 1.2 to 4.0 are preferable.
In the block polymer used in the present invention, the ratio of each monomer and the ratio of each unit are not particularly limited, and various examples can be mentioned. For example, the first polymerizable monomer and the second polymerizable monomer can be used. The ratio of the former / latter molar ratio is 1/99 to 80/20, and the ratio of the first polymerizable monomer to the third polymerizable monomer is 1/99 to 80/20. The ratio of the first polymer unit and the second polymer unit is 10/90 to 90/10 in terms of the former / the latter molar ratio.

  The block polymer used in the present invention includes, for example, a step A in which a first polymerizable monomer having a hydroxyl group and a second polymerizable monomer are polymerized by living polymerization to obtain a first polymer unit, and then a hydroxyl group-containing first polymer. It can be obtained by a production method having one polymerizable monomer and a step B in which a third polymerizable monomer different from the second polymerizable monomer is added to chain extend the second polymer unit.

The first polymerizable monomer having a hydroxyl group to be used first and the first polymerizable monomer having a hydroxyl group to be used later are preferably the same type of monomers, but are not limited thereto.
Living polymerization includes anionic polymerization, atom transfer radical polymerization (ATRP), nitroxide living radical polymerization (NMP), reversible addition-fragmentation chain transfer (RAFT) polymerization, organic tellurium-mediated living radical polymerization (TERP), reversible chain transfer catalytic polymerization. (RTCP) or the like can be used.

Living radical polymerization reversibly protects the growing radical in radical polymerization, and the molecular chain is gradually changed by repeating deprotection (activation), addition of monomer (growth), and protection (inactivation) of the protecting group, The polymer grows almost uniformly and a polymer with a narrow molecular weight distribution is obtained. Even if the monomer is depleted from the reaction system, polymerization is started by supplying a new monomer, and chain elongation occurs. Among them, reversible addition-fragmentation chain transfer polymerization (RAFT) using a thioester as a protecting group which is a chain transfer agent has many polymerizable monomer species, and is capable of directly copolymerizing an acrylic acid ester or a methacrylic acid ester having a hydroxyl group. preferable.
In this RAFT polymerization, a thiocarbonate compound having a structure represented by the general formula (1) can be used as a chain transfer agent.

（Ｒは、一価の基を示し、Ｚは、一価の基を示す。）

(R represents a monovalent group, and Z represents a monovalent group.)

Here, as R, cumyl group, cyanopropyl group, phenylpropyl group, cyanophenylmethyl group, ethylcarboxypropyl group, 2,4,4-trimethylpentan-2-yl group, 1-cyanoethyl group, 1-phenyl Preferred examples include an ethyl group, a tertiary butyl group, a cyanomethyl group, and a benzyl group.
Z is preferably a phenyl group, a methylthioyl group, a pyrrole group, a methyl group, a phenoxy group, an ethoxy group, a dimethylamino group, or the like.

  Specific examples of these chain transfer agents include cumyl dithiobenzoate, 2-cyano-2-propylbenzothioate, 4-cyano-4 [(dodecylsulfanylthiocarbonyl) sulfanyl] pentanoic acid, cyanomethylmethyl (phenyl) Carbamodithioate, 4-cyano-4- (phenylcarbonothioylthio) pentanoic acid, 2-cyano-2-propyldodecyltrithiocarbonate, 2- (dodecylthiocarbonothioylthio) -2-methylpropionic acid, Although cyanomethyl dodecyl trithio carbonate etc. are mentioned and these are marketed, it is not limited to these.

  In the present invention, the polymerizable monomer includes a monomer having a polymerizable carbon-carbon unsaturated double bond, and specifically includes an acrylic monomer, a styrene monomer, acrylonitrile, and the like.

Here, the acrylic monomer means a monomer having an acryloyl group (CH═CH—CO—) or a methacryloyl group (CH═C (CH ₃ ) —CO—), and the acrylic polymer has these groups. A polymer obtained by polymerization using at least a part of a monomer.
In the present invention, an acrylic polymer using an acrylic monomer or a styrene monomer as a polymerizable monomer is preferable. In the present invention, the first polymerizable monomer is not particularly limited as long as it is a hydroxyl group-containing monomer, such as 2-hydroxymethyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, and acrylic acid. 2-hydroxybutyl, 2-hydroxyhexyl acrylate, hydroxyalkyl acrylate such as 2-propylheptyl acrylate, monoacrylate of cycloalkylene dimethanol such as 1,4-cyclohexanedimethanol monoacrylate, methacrylic acid 2-hydroxymethyl, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxybutyl methacrylate, hydroxyalkyl methacrylate such as 2-hydroxyhexyl methacrylate, 1,4-cyclohexane Such cycloalkylene range methanol monomethacrylate such as monovinyl methacrylate. Of these, preferred are 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, and the like.

  The second polymerizable monomer and the third polymerizable monomer include acrylic monomers, styrenic monomers, acrylonitrile, etc., other than the first polymerizable monomer, and acrylic monomers are preferred. The second polymerizable monomer is preferably an acrylic acid ester or a methacrylic acid ester, and the third polymerizable monomer is preferably an acrylic acid ester or a methacrylic acid ester other than the second polymerizable monomer.

Among these, as a suitable monomer combination in the adhesive composition of the present invention, a first polymerizable monomer; a (meth) acrylic acid ester having a hydroxyl group, a second and a third monomer; a branch of (meth) acrylic acid And, for example, (meth) acrylic acid-2-ethylhexyl, (meth) acrylic acid-2-propylheptyl, (meth) acrylic acid-2-butyloctyl, etc.).
((Meth) acrylic acid OO means acrylic acid XX or methacrylic acid XX.)

  In the present invention, the third polymerizable monomer is preferably a monomer having a lower dielectric constant than the second polymerizable monomer. Specific examples include (meth) acrylic acid-2-ethylhexyl as the second polymerizable monomer, (meth) acrylic acid-2-propylheptyl as the third polymerizable monomer, and (meth) acrylic acid-2- A combination using butyloctyl and the like can be mentioned.

  In the present invention, the block polymer is produced by using a thiocarbonate compound having a structure represented by the general formula (1) as a chain transfer agent, and a first polymerizable monomer (for example, an acrylic ester having a hydroxyl group or methacrylic acid). Ester) and the second polymerizable monomer are polymerized by living polymerization to synthesize the first polymer unit. When the polymerization proceeds to some extent, the polymer that becomes the first polymer unit is reprecipitated or distilled under reduced pressure. After the recovery, the second polymer unit can be chain extended by adding it together with the first polymerizable monomer and the third polymerizable monomer. In this case, a small amount of radical initiator may be added.

  In addition, a thiocarbonate compound having a structure represented by the general formula (1) is used as a chain transfer agent, and a first polymer unit and a second polymerizable monomer are polymerized by living polymerization to synthesize a first polymer unit. When the polymerization has progressed to some extent, the first polymer monomer and the third polymer monomer are added to the same reactor and the second polymer unit is chain-extended, whereby the block polymer used in the present invention is obtained. Can be obtained.

  The first polymerizable monomer having a hydroxyl group to be used first, the second monomer polymerizable with this, the first polymerizable monomer to be charged later, the molar amount of each of the first polymerizable monomer and the polymerizable third monomer, and By controlling the molar ratio of the thiocarbonate compound represented by the general formula (1), the molecular weight of the obtained block polymer, the molecular weight (chain length) of the first polymer unit, the molecular weight (chain) of the second polymer unit Length) can be adjusted.

  Generally, the molar ratio of the chain transfer agent, specifically the compound represented by the general formula (1) and the radical initiator is preferably 20/1 to 1/5, and more preferably 10/1 to 1/4. The ratio of the compound represented by the general formula (1) to the radical initiator is 20/1 or less, which is industrially preferable because the polymerization reaction rate can be increased while maintaining monodispersity. By setting the number to 5 or more, chain transfer from the radical initiator directly to the monomer can be avoided, and the random polymer different from the block polymer of the present invention, the first polymer unit alone, and the second polymer unit alone It is possible to obtain a good block polymer by suppressing the by-production of the polymer.

  The temperature of the polymerization reaction varies depending on the decomposition temperature of the radical initiator to be used, and is not particularly limited, but it is generally preferable to carry out at a half-life decomposition temperature of minus 2 ° C. to plus 20 ° C. By controlling the temperature within this range with respect to the half-life decomposition temperature, it is possible to reduce the molecular weight distribution, and it is possible to suppress a decrease in blocking due to a by-product of a polymer not having the structure of the general formula (1).

  Radical initiators for synthesizing the block polymers of the present invention include benzoyl peroxide, acetyl peroxide, lauroyl peroxide, di-t-butyl peroxide, cumene hydroperoxide, t-butyl hydroperoxide, dicumyl peroxide and the like. Examples thereof include oxide initiators, azo initiators such as AIBN (2,2′-azobisisobutyronitrile), V-65 (azobisdimethylvaleronitrile), and the like. Among them, AIBN (2,2′-azobisisobutyronitrile) is preferable.

  The block polymer of the present invention can be synthesized by solution polymerization, suspension polymerization, emulsion polymerization, solid phase polymerization, etc., but solution polymerization may be used to obtain a resin having a weight average molecular weight of 2,000 to 300,000. Preferably, suspension polymerization is preferred to obtain a resin having a weight average molecular weight of 300,000 to 1,000,000. The polymerization method is appropriately selected depending on the polarity and reactivity of the monomer to be used, but when using an acrylic acid ester or methacrylic acid ester having a hydroxyl group, a solution for synthesizing an acrylic polymer soluble in a solvent from the viewpoint of its solubility. It is preferable to carry out by polymerization.

  Although there is no restriction | limiting in particular in the molecular weight of the block polymer used by this invention, Generally 10,000-500,000 are preferable at a weight average molecular weight. In general, the molecular dispersity is preferably 1.2 to 4.0. In addition, molecular weight can be calculated | required by measuring by a gel permeation chromatography method and converting using a standard polystyrene calibration curve.

  Solution polymerization is performed by dissolving a polymerizable monomer, a chain transfer agent, a radical initiator, and a resin to be produced in a solvent that can be dissolved, and then heating to a temperature determined by the radical initiator. At this time, it is possible to carry out the polymerization under air, but it is preferred to carry out under nitrogen.

  The solvent used in the solution polymerization is not particularly limited as long as it can dissolve a polymerizable monomer, a chain transfer agent, a radical initiator, and a resin to be formed, but preferably has a boiling point equal to or higher than the temperature at which the polymerization is performed. When the temperature at which the polymerization is carried out is higher than the boiling point of the solvent used, the polymerization can be carried out by a reaction under pressure.

  As the organic solvent to be used, methoxyethanol, ethoxyethanol, toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanol, cyclohexanone, butyl acetate, chlorobenzene, dioxane, propylene glycol monomethyl ether and the like are used, and are not particularly limited. These can be used alone or in combination.

  In RAFT polymerization, there is generally no chain transfer from the acrylic growth end to the methacrylate monomer. Therefore, the monomer blending procedure and combination when copolymerizing a plurality of monomers are important. Therefore, when simultaneously charging a plurality of monomers, it is preferable to carry out a combination of only monomers having an acryloyl group or only a monomer having a methacryloyl group.

  In the present invention, in order to grow a polymer stepwise by block polymerization, polymerization is performed with a combination of monomers having an acryloyl group alone, or after polymerization of a monomer having a methacryloyl group with a combination of monomers only having a methacryloyl group. It is preferable to polymerize a monomer having an acryloyl group.

In the adhesive composition of the present invention, an acrylic polymer other than the block polymer can be used in combination, but the block polymer is preferably the main component of the acrylic polymer, preferably 80% by mass or more, Most preferred is the total amount.
In the adhesive composition of this invention, the compound which has a functional group which can react with a hydroxyl group can be used as a hardening | curing agent as needed.

  As a hardening | curing agent used for this invention, what has 2 or more of functional groups which can react with the hydroxyl group contained in a block polymer preferably in 1 molecule is preferable. For example, a known polyfunctional isocyanate compound, a known polyfunctional epoxy compound, and the like can be suitably used. These can also be used in combination.

  Examples of the polyfunctional isocyanate compound include aromatic diisocyanate, aliphatic diisocyanate, araliphatic diisocyanate, and alicyclic diisocyanate. In addition, so-called adducts obtained by modifying a diisocyanate compound with a polyol component, burettes obtained by reacting a diisocyanate compound with water, trimers having an isocyanurate ring formed from three molecules of an diisocyanate compound (isocyanurate form), and the like can also be used.

  When a curing agent is used, there is no particular limitation on the mixing ratio of the acrylic polymer total amount including the block polymer and the curing agent. For example, it is preferable to use 1 to 50 parts by weight of the curing agent with respect to 100 parts by weight of the acrylic polymer. .

  In addition, the adhesive composition of the present invention may be used in combination with other resins, polyester resins, amino resins, epoxy resins, polyurethane resins, and the like, if necessary. You may mix | blend additives, such as an agent, various fillers, a coloring agent, a ultraviolet absorber, an antifoamer, a light stabilizer, and antioxidant.

  There is no restriction | limiting in particular about the method of stirring and mixing each component uniformly, The method of using various stirrers and various kneading apparatuses is mentioned. The obtained adhesive composition can be used as an adhesive as it is. Moreover, a varnish-like adhesive composition can also be formed in a film form and used as an adhesive film.

For example, the adhesive film can be laminated on a metal foil such as a copper foil to form a metal foil with an adhesive layer.
The method for producing the adhesive film is not particularly limited except that the adhesive composition of the present invention is formed into a film and then dried. For example, a method in which each component of the adhesive composition is dissolved or dispersed in an organic solvent to form a varnish, applied onto a support, and then blown and heated as necessary to dry and remove the solvent is preferable. is there. The support is not particularly limited in shape and material as long as it can be applied, but a film is preferable.

  As the support film, a polyester film such as a polyethylene terephthalate film, a plastic film such as a polyimide film, a polyethylene film, a polyolefin film such as a polypropylene film, and the like can be used. You can also The support film can be peeled off at the time of use and only the adhesive layer can be used, or it can be used together with the support film and removed later.

  Moreover, after apply | coating and drying an adhesive composition on the above-mentioned support body film, a protective film can also be laminated | stacked and used on an adhesive composition. As this protective film, the same film as the support film can be used. As a method for applying the adhesive composition to the support film, a known method can be used. For example, a dip coating method, a flow coating method, a spin coating method, a curtain coating method, a knife coating method, a roll coating method, Wire bar coating, doctor blade coating, spray coating, ultrasonic coating, inkjet coating, die coating, gravure coating, screen printing, brush coating, sponge coating, and the like can be applied.

The thickness of the adhesive film of the present invention is not particularly limited, but is preferably in the range of 1 to 250 μm in terms of stress relaxation effect, adhesiveness and the like.
The block polymer used in the adhesive composition of the present invention has a hydroxyl group dispersed in the polymer chain, and further modifies a part of this hydroxyl group to give a double bond to make it photocurable. A photopolymerizable initiator can be further blended in the adhesive composition. In this case, double bonds are dispersed in the polymer chain, the photocurability is improved, and the physical properties of the cured product can be stabilized.

Examples are described below, but the present invention is not limited to these examples.
(Synthesis Example 1)
In a 500 ml separable flask equipped with a reflux condenser, a thermometer, a stirrer, and a nitrogen introduction tube, 13.9 g (120 mmol) of acrylic acid-2-hydroxyethyl (HEA, manufactured by Wako Pure Chemical Industries, Ltd.), acrylic acid- 2-ethylhexyl (2EHA, manufactured by Wako Pure Chemical Industries, Ltd.) 44.2 g (240 mmol), cumyl dithiobenzoate 112 mg (0.41 mmol), azobisisobutyronitrile (Wako Pure Chemical Industries, Ltd., purity 98%) 44 mg ( 0.27 mmol) methyl isobutyl ketone (Wako Pure Chemical Industries, Ltd.) 58g was charged, nitrogen was bubbled at room temperature and stirred for 40 minutes. The temperature was raised to 70 ° C. and stirred for 30 minutes, then the temperature was raised to 75 ° C. and stirred for 6 hours, and the solid content and molecular weight were measured. The polymerization rate calculated from the solid content was 91%, the weight average molecular weight (Mw) of the HEA / 2EHA unit was 149,000, and the number average molecular weight (Mn) was 55,600. 13.9 g (120 mmol) of HEA, 51.0 g (240 mmol) of acrylic acid-2-propylheptylstyrene (Wako Pure Chemical Industries, Ltd.) and 35 g of methyl isobutyl ketone were added to this reaction solution, and stirring was further continued at 80 ° C. When the viscosity of the reaction solution increased, 20 g of methyl isobutyl ketone that had been bubbled with nitrogen for 30 minutes was added and further stirred. Stir at 80 ° C. for 4 hours. After completion of the reaction, a methyl isobutyl ketone solution of acrylic polymer was obtained. The weight average molecular weight (Mw) of the obtained polymer was 323,000, and the number average molecular weight (Mn) was 76,300.

(Comparative Synthesis Example 1)
In a 500 ml separable flask equipped with a reflux condenser, a thermometer, a stirrer, and a nitrogen introduction tube, 27.8 g (240 mmol) of acrylic acid-2-hydroxyethyl (HEA, manufactured by Wako Pure Chemical Industries, Ltd.), acrylic acid- 2-ethylhexyl (2EHA, Wako Pure Chemical Industries, Ltd.) 44.2 g (240 mmol), 2-propylheptyl acrylate (Wako Pure Chemical Industries, Ltd.) 51.0 g (240 mmol), cumyldithiobenzoate 71 mg (0.26 mmol) ), Azobisisobutyronitrile (Wako Pure Chemical Industries, Ltd., purity 98%) 22 mg (0.13 mmol) Toluene / propylene glycol monomethyl ether (2/3 weight ratio) mixture 75 g was charged, and nitrogen was bubbled at room temperature. For 40 minutes. The temperature was raised to 65 ° C. and stirred for 30 minutes, then the temperature was raised to 70 ° C. and stirred for 2 hours, and further stirred at 80 ° C. for 2 hours, and the solid content and molecular weight were measured. The polymerization rate calculated from the solid content was 90%, the weight average molecular weight (Mw) of HEA / 2EHA / 2PHA was 312,000, and the number average molecular weight (Mn) was 159,000.

(Comparative Synthesis Example 2)
In a 500 ml separable flask equipped with a reflux condenser, a thermometer, a stirrer, and a nitrogen introduction tube, 27.8 g (240 mmol) of acrylic acid-2-hydroxyethyl (HEA, manufactured by Wako Pure Chemical Industries, Ltd.), acrylic acid- 2-ethylhexyl (2EHA, manufactured by Wako Pure Chemical Industries, Ltd.) 44.2 g (240 mmol), azobisisobutyronitrile (Wako Pure Chemical Industries, Ltd., purity 98%) 22 mg (0.13 mmol) toluene / propylene glycol monomethyl ether ( 2/3 weight ratio) 75 g of the mixed solution was charged, nitrogen was bubbled at room temperature, and the mixture was stirred for 40 minutes. The temperature was raised to 65 ° C. and stirred for 30 minutes, then the temperature was raised to 70 ° C. and stirred for 2 hours, and further stirred at 80 ° C. for 2 hours, and the solid content and molecular weight were measured. The polymerization rate calculated from the solid content was 90%, the weight average molecular weight (Mw) of HEA / 2EHA / 2PHA was 360,000, and the number average molecular weight (Mn) was 88,000.

Example 1
6.5 g of polyisocyanate (Coronate L) was blended with 20 g of the acrylic resin obtained in Synthesis Example 1 (in terms of solid content) to obtain an adhesive composition (varnish). This was applied onto a release-treated PET film so as to have a dry thickness of 100 μm, dried at 80 ° C. for 30 minutes, and then cured at 130 ° C. for 2 hours to obtain an adhesive film. The same compound was applied to copper foil F2-WS-18 (Furukawa Circuit Foil, trade name, thickness 18 μm) so that the thickness after drying was 50 μm, dried at 80 ° C. for 30 minutes, and then 130 ° C. 2 Time-cured to produce a copper foil laminate.

(Comparative Examples 1 and 2)
A film for measuring a dielectric constant and a copper foil laminate were prepared in the same manner as in Examples except that Comparative Synthesis Examples 1 and 2 were used.

[Evaluation]
[Measurement of dielectric constant]
A power supply electrode, a ground electrode, and a guard electrode were prepared on both sides of the adhesive cured film, and the capacitance was measured to measure a dielectric constant of 10 KHz.

[Measurement of copper foil adhesion]
The copper foil laminate was cut into a strip shape having a width of 10 mm, the adhesive surface was bonded to a glass plate with a double-sided tape, and the peel strength between the copper foil and the adhesive interface was measured at a pulling speed of 50 mm / min.
[Measurement of solid content and reaction rate]
The solid content of the reaction solution or acrylic polymer varnish was precisely weighed in an aluminum petri dish that had been weighed and heated at 150 ° C. for 15 minutes, and then weighed again to obtain the following formula.

[Measurement of molecular weight]
The number average molecular weight (Mn), weight average molecular weight (Mw), and Mw / Mn of the acrylic polymers of Examples and Comparative Examples were measured by GPC (gel permeation chromatography) by measuring the chromatogram of the molecular weight distribution of the acrylic polymer. It calculated | required in conversion from the elution time of the standard polystyrene in 25 degreeC. In addition, the measuring apparatus uses Tosoh Co., Ltd. EcoSEC, HLC-8320GPC, and GPC uses tetrahydrofuran as an eluent, and columns include Gel Pack GL-A-150 and Gel Pack GL-A-10 (manufactured by Hitachi High-Technologies Corporation). (Product name) directly connected.

[Evaluation results]

Claims (7)

  A first polymer unit and a hydroxyl group, which is an acrylic polymer obtained by polymerizing a polymerizable monomer having three or more components, and includes a structure derived from the first polymerizable monomer having a hydroxyl group and a structure derived from the second polymerizable monomer An adhesive comprising a block polymer having a second polymer unit including a structure derived from a third polymerizable monomer different from the structure derived from the first polymerizable monomer having the structure and the second polymerizable monomer Composition.   The adhesive composition according to claim 1, wherein the second polymerizable monomer is an acrylic ester or a methacrylic ester.   The adhesive composition according to claim 1 or 2, wherein the third polymerizable monomer is an acrylic ester or a methacrylic ester different from the second polymerizable monomer.   The adhesive composition according to any one of claims 1 to 3, wherein the third polymerizable monomer has a lower dielectric constant than the second polymerizable monomer.   The adhesive composition according to any one of claims 1 to 4, wherein the block polymer has a weight average molecular weight of 10,000 to 500,000.   The adhesive composition according to claim 1, wherein the block polymer has a molecular weight dispersity of 1.2 to 4.0.   The adhesive film formed in a film form using the adhesive composition in any one of Claims 1-6.