JP2020029530A - Acrylic copolymer and adhesive composition containing the same - Google Patents

Abstract

To provide an acrylic copolymer that can be obtained through a simple process from an industrially available phenolic compound.SOLUTION: The acrylic copolymer comprises a repeating unit derived from a phenolic hydroxyl group-containing acrylic monomer represented by formula (A) below and a repeating unit derived from an acrylic monomer represented by formula (B) below. In formula (A), Rrepresents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms; m is 2 to 3; and n is 1 to 4, where the sum of m and n is 3 to 6. In formula (B), Rrepresents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms; Rrepresents a hydrogen atom, an alkyl group having 1 to 18 carbon atoms, an alkenyl group having 2 to 18 carbon atoms or an aromatic group having 6 to 20 carbon atoms; and X represents O or NH.SELECTED DRAWING: None

Description

  The present invention relates to an acrylic copolymer that can be used as an adhesive or the like applicable to water and wet surfaces.

  Acrylic copolymers have various properties according to their uses, and new materials having unprecedented functions are being actively studied. Adhesives generally have the disadvantage that when the surface of the substrate to be bonded is wet and contains moisture, sufficient adhesive strength cannot be obtained and the substrate is peeled off. (80% or more), there is a demand for a functional adhesive exhibiting sufficient adhesive performance.

  In order to obtain an acrylic copolymer exhibiting adhesiveness in water, a major technique that has been conventionally proposed is an atomic group having a catechol group at a terminal in a side chain of the copolymer (for example, 3,4-dihydroxy group). Phenylalanine (DOPA). Patent Literature 1, Patent Literature 2, and Non-Patent Literature 1 disclose an acrylic copolymer obtained by using dopamine derived from DOPA in a living body, and then inducing to acrylamide.

JP 2012-233059 A Japanese Patent Publication No. 2010-501027

M. Naito et al., Polym. Chem., 8, 1654 (2017)

However, the above-mentioned catechol group-containing copolymers all use DOPA and dopamine obtained from nature as raw materials, and have a problem that the extraction step is complicated and requires a lot of time and cost. Further, there is a problem that the adhesiveness (adhesive strength and adhesive shear strength) is not sufficient.
An object of the present invention is to solve the above problems and to provide an acrylic copolymer obtained from industrially available phenolic hydroxyl compounds in a simple step, and when used as an adhesive, An object of the present invention is to provide an acrylic copolymer having excellent adhesive properties (adhesive strength and adhesive shear strength).

［式（Ａ）中、Ｒ^１は水素原子又は炭素数１〜８のアルキル基であり、ｍは２〜３であり、ｎは１〜４であり、ｍとｎの合計は３〜６である。］

［式（Ｂ）中、Ｒ^２は水素原子又は炭素数１〜８のアルキル基であり、Ｒ^３は水素原子、炭素数１〜１８のアルキル基、炭素数２〜１８のアルケニル基、又は炭素数６〜２０の芳香族基であり、Ｘは、Ｏ又はＮＨである。］ The object of the present invention is to
A repeating unit derived from a phenolic hydroxyl group-containing acrylic monomer represented by the following formula (A):
Including a repeating unit derived from an acrylic monomer represented by the following formula (B):
It is solved by an acrylic copolymer.

[In the formula (A), R ¹ is a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, m is 2 to 3, n is 1 to 4, and the sum of m and n is 3 to 6. is there. ]

[In the formula (B), R ² is a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and R ³ is a hydrogen atom, an alkyl group having 1 to 18 carbon atoms, an alkenyl group having 2 to 18 carbon atoms, or a carbon atom. It is an aromatic group of the formulas 6 to 20, and X is O or NH. ]

  According to the present invention, an acrylic copolymer can be provided in a simple step from a commercially available phenolic hydroxyl group-containing compound. In addition, acrylic copolymers provide adhesives with excellent adhesion (adhesive strength and adhesive shear strength).

［式（Ａ）中、Ｒ^１は水素原子又は炭素数１〜８のアルキル基であり、ｍは２〜３であり、ｎは１〜４であり、ｍとｎの合計は３〜６である。］ <Phenolic hydroxyl group-containing acrylic monomer (A)>
The phenolic hydroxyl group-containing acrylic monomer is represented by the following formula (A).

[In the formula (A), R ¹ is a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, m is 2 to 3, n is 1 to 4, and the sum of m and n is 3 to 6. is there. ]

Specific examples of the phenolic hydroxyl group-containing acrylic monomer (A) are as follows. In the following formula, R ¹ is a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and n is 1 to 4 (when the number of OH groups is 2) or 1 to 3 (when the number of OH groups is 3) Case).

Further specific examples of the phenolic hydroxyl group-containing acrylic monomer (A) are as follows.

R ¹ is preferably a hydrogen atom or a methyl group, and particularly preferably a hydrogen atom.
n is preferably 2 to 3 from the viewpoint of adhesiveness, and particularly preferably n is 2.
m is preferably 2 from the viewpoint of adhesiveness.

The position of the phenolic hydroxyl group ((OH) _m ) is not particularly limited, but it is preferable that the phenolic hydroxyl group is adjacently substituted, and it is preferable that the phenolic hydroxyl group be a 3,4-dihydroxyphenyl group or a 2,3-dihydroxyphenyl group. , 2,3,4-trihydroxyphenyl group, 3,4,5-trihydroxyphenyl group, and 2,4,5-trihydroxyphenyl group, and from the viewpoint of adhesiveness, 3,4-dihydroxy group is particularly preferable. It is a phenyl group.
As the phenolic hydroxyl group-containing acrylic monomer (A), a plurality of types having different n and / or m may be used in combination.

  In a preferred embodiment of the phenolic hydroxyl group-containing acrylic monomer (A), m is 2, n is 2 to 4, and a particularly preferred embodiment contains a 3,4-dihydroxyphenyl group (m = 2), and n is 2-4.

で示されるフェノール性水酸基含有化合物にアクリルアミドメチル基を付加させる反応により製造される。 <Method for producing phenolic hydroxyl group-containing acrylic monomer (A)>
The phenolic hydroxyl group-containing acrylic monomer is prepared by reacting the phenolic hydroxyl group-containing acrylic monomer with a compound represented by the formula:

It is produced by a reaction of adding an acrylamidomethyl group to a phenolic hydroxyl group-containing compound represented by

［式中、Ｒ^１は水素原子又は炭素数１〜８のアルキル基であり、ｍは２〜３であり、ｎは１〜４であり、ｍとｎの合計は３〜６である。］
ｎは、フェノール性水酸基含有化合物に対するヒドロキシメチル（メタ）アクリルアミドの量を増加させることによって、大きくすることができる。

[Wherein, R ¹ is a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, m is 2 to 3, n is 1 to 4, and the sum of m and n is 3 to 6. ]
n can be increased by increasing the amount of hydroxymethyl (meth) acrylamide relative to the phenolic hydroxyl group-containing compound.

  Specific examples of the phenolic hydroxyl group-containing compound used in the present invention include catechol, resorcinol, hydroquinone, pyrogallol, hydroxyquinol, and phloroglucinol. And catechol is particularly preferred.

<Acid catalyst>
The acid catalyst used in the present invention is not particularly limited as long as it belongs to Bronsted acid and does not adversely affect the reaction. Specifically, mineral acids such as sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid and hydrofluoric acid, sulfonic acids such as methanesulfonic acid, trifluoromethanesulfonic acid and toluenesulfonic acid, acetic acid, propionic acid, butyric acid, benzoic acid and the like And cation exchange resins having a carboxylic acid residue. The amount of the acid catalyst to be used is preferably 0.001 to 0.5 mol, particularly preferably 0.01 to 0.3 mol, per 1 mol of the phenolic compound.

<Solvent>
The solvent used in the present invention is not particularly limited as long as it can dissolve the raw materials and products and does not adversely affect the reaction. Specifically, aliphatic alcohols (methanol, ethanol, etc.), aromatic hydrocarbons (toluene, xylene, etc.), halogenated hydrocarbons (dichloromethane, chloroform, etc.), amides (N, N-dimethylformamide, N , N-dimethylacetamide, etc.).
In addition, a solvent may use multiple types together.

  The amount of the solvent used is not particularly limited as long as the raw material and the product can be dissolved. Usually, the amount of the solvent used is preferably 1 to 10 times, more preferably 2 to 8 times the mass of the phenolic hydroxyl group-containing compound (such as catechol) containing two or more phenolic hydroxyl groups, Particularly preferably, it is 3 to 6 times.

<Reaction conditions>
In order to obtain the phenolic hydroxyl group-containing acrylic monomer (A), a phenolic hydroxyl group-containing compound having two or more phenolic hydroxyl groups and N-hydroxymethyl (meth) acrylamide are dissolved in a solvent. The reaction temperature is not particularly limited as long as it does not adversely affect the progress of the reaction. Usually, it is carried out at -10 to 150C, preferably 10 to 100C, particularly preferably 20 to 80C. The reaction time is not particularly limited, but usually the reaction is sufficiently completed in 0.1 to 10 hours.
The amount of N-hydroxymethyl (meth) acrylamide to be used is preferably at least twice the molar amount of the phenolic hydroxyl group-containing compound having two or more phenolic hydroxyl groups, depending on the type of raw material and reaction conditions. Can be increased or decreased.

<Acrylic monomer (B)>
The acrylic monomer is represented by the following formula (B).

[In the formula (B), R ² is a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and R ³ is a hydrogen atom, an alkyl group having 1 to 18 carbon atoms, an alkenyl group having 2 to 18 carbon atoms, or a carbon atom. It is an aromatic group of the formulas 6 to 20, and X is O or NH. ]

Alkyl and alkenyl groups may be linear, branched or cyclic.
The aromatic group includes an aryl group and a benzyl group.
R ² is preferably a hydrogen atom or a methyl group. R ³ is preferably an alkyl group, for example, an alkyl group having 4 to 12 carbon atoms. X is preferably O.

  As the acrylic monomer (B), specifically, (meth) acrylic acid alkyl ester (that is, acrylic acid alkyl ester and methacrylic acid alkyl ester), and N-alkyl (meth) acrylamide (that is, N-alkylacrylamide and N-alkylacrylamide) -Alkyl methacrylamide).

  In this specification, “(meth) acrylic acid” means acrylic acid or methacrylic acid, and “(meth) acrylamide” means acrylamide or methacrylamide.

  Specific examples of the alkyl (meth) acrylate include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, and (meth) acrylate. ) Hexyl acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, dodecyl (meth) acrylate, squalyl (meth) acrylate, vinyl (meth) acrylate, allyl (meth) acrylate, Phenyl (meth) acrylate, benzyl (meth) acrylate and the like.

  Specific examples of the N-alkyl (meth) acrylamide include N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-propyl (meth) acrylamide, N-isopropyl (meth) acrylamide, and N-butyl (meth). ) Acrylamide, N-hexyl (meth) acrylamide, N-octyl (meth) acrylamide, N-2-ethylhexyl (meth) acrylamide, N-dodecyl (meth) acrylamide, N-squaryl (meth) acrylamide, N-vinyl (meth) ) Acrylamide, N-allyl (meth) acrylamide, N-phenyl (meth) acrylamide, N-benzyl (meth) acrylamide and the like.

The acrylic monomer (B) is preferably butyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and (meth) acrylic acid from the viewpoint of adhesiveness. Dodecyl, squaryl (meth) acrylate, N-butyl (meth) acrylamide, N-hexyl (meth) acrylamide, N-octyl (meth) acrylamide, N-2-ethylhexyl (meth) acrylamide, N-dodecyl (meth) acrylamide , N-squaryl (meth) acrylamide, particularly preferably butyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, dodecyl (meth) acrylate It is.
Note that a plurality of types of acrylic monomers (B) may be used in combination.

［式（Ａ）中、Ｒ^１は水素原子又は炭素数１〜８のアルキル基であり、ｍは２〜３であり、ｎは１〜４である。］

［式（Ｂ）中、Ｒ^２は水素原子又は炭素数１〜８のアルキル基であり、Ｒ^３は水素原子、炭素数１〜１８のアルキル基、炭素数２〜１８のアルケニル基、又は炭素数６〜２０の芳香族基であり、Ｘは、Ｏ又はＮＨである。］ <Acrylic copolymer>
Acrylic copolymer is
It includes a repeating unit derived from the phenolic hydroxyl group-containing acrylic monomer represented by the formula (A) and a repeating unit derived from the acrylic monomer represented by the formula (B).

[In the formula (A), R ¹ is a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, m is 2 to 3, and n is 1 to 4. ]

[In the formula (B), R ² is a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and R ³ is a hydrogen atom, an alkyl group having 1 to 18 carbon atoms, an alkenyl group having 2 to 18 carbon atoms, or a carbon atom. It is an aromatic group of the formulas 6 to 20, and X is O or NH. ]

  "The repeating unit derived from the phenolic hydroxyl group-containing acrylic monomer represented by the formula (A)" means a structure in which the ethylenically unsaturated double bond contained in the formula (A) has become a single bond by a polymerization reaction. I do. The same applies to “the repeating unit derived from the acrylic monomer represented by the formula (B)”.

  In the polymerization, an addition polymerization reaction in which the ethylenically unsaturated double bond in the phenolic hydroxyl group-containing acrylic monomer (A) and the acrylic monomer (B) is opened, the monomers are bonded to each other, and from the phenolic hydroxyl group-containing acrylic monomer (A) An acrylic copolymer containing a repeating unit derived from the acrylic monomer (B) and a repeating unit derived therefrom is formed.

The repeating unit derived from the phenolic hydroxyl group-containing acrylic monomer (A) may include n different repeating units. The proportion of the repeating unit in which n is 2 or more is preferably 10 mol% or more, more preferably 30 mol% or more, and still more preferably 50 mol, based on the total of the repeating units in which n is 1 to 4. %, Particularly preferably 100 mol%.
When n contains a repeating unit derived from the phenolic hydroxyl group-containing acrylic monomer (A) of 2 or more, the acrylic copolymer has a three-dimensional cross-linked structure, and thus has excellent adhesion when used as an adhesive. N is preferably 2 to 3, and particularly preferably 2 from the viewpoint that it is possible to provide an acrylic copolymer having properties and to have more excellent adhesion.

The molar ratio of the repeating unit derived from the phenolic hydroxyl group-containing acrylic monomer (A) and the repeating unit derived from the acrylic monomer (B) in the acrylic copolymer is determined by the adhesiveness (adhesive strength and adhesive shear strength). From the viewpoint, the ratio is preferably 1:99 to 99: 1, more preferably 1:99 to 40:60, and particularly preferably 5:95 to 20:80.
The weight average molecular weight of the acrylic copolymer is preferably 1,000 to 1,000,000, more preferably 10,000 to 300,000, and particularly preferably 20,000 to 200,000. The mass average molecular weight is measured by GPC (gel permeation chromatography) (converted by polystyrene).

In a preferred embodiment of the acrylic copolymer, in the formula (A), R ¹ is a hydrogen atom, and in the formula (B), R ² is a hydrogen atom or a methyl group, and R ³ is linear or It is a branched alkyl group having 1 to 18 carbon atoms, and X is O.

The acrylic copolymer contains a repeating unit derived from a phenolic hydroxyl group-containing acrylic monomer (A) and a repeating unit derived from an acrylic monomer (B), and is a repeating unit derived from another monomer (C). May be included.
The other monomer (C) is not particularly limited as long as it is a monomer containing an ethylenically unsaturated double bond, and specific examples include ethylene, propylene, vinyl acetate, styrene, vinyl chloride, 1,3-butadiene, -Methyl-1,3-butadiene and the like.
The proportion of the repeating unit derived from the other monomer (C) is preferably 1 to 50 mol%, more preferably 0.1 to 30 mol%, based on all the repeating units, from the viewpoint of adhesiveness. More preferably, it is 0 to 10 mol%, particularly preferably 0 mol%.

  The repeating unit derived from each of (A), (B) and (C) may include a plurality of types of repeating units.

<Method for producing acrylic copolymer>
The acrylic copolymer is obtained by copolymerizing a phenolic hydroxyl group-containing acrylic monomer (A), an acrylic monomer (B) and, if necessary, another monomer (C).

<Polymerization method>
The synthesis of the acrylic copolymer is not particularly limited, but radical polymerization is generally used. Among radical polymerizations, living radical polymerization (RAFT polymerization) and atom transfer radical polymerization (ATRP) can be used, and the polymerization form may be any of random copolymerization and block copolymerization.

<Radical polymerization initiator>
The radical polymerization initiator is not particularly limited as long as it can radically polymerize the monomer, and examples thereof include hydrogen peroxide, isobutyl peroxide, t-butyl peroxide, octanoyl peroxide, decanoyl peroxide, lauroyl peroxide, and peroxide. Peroxides such as benzoyl, potassium persulfate, ammonium persulfate and sodium persulfate; azobisisobutyronitrile (AIBN), 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2, Azo compounds such as 2'-azobis (2-cyclopropylpropionitrile), 2,2'-azobis (2-methylpropionitrile), 2,2'-azobis (2-methylbutyronitrile); peroxides Hydrogen-ascorbic acid, hydrogen peroxide-ferrous chloride, persulfate-bisulfite sodium And redox initiators such as benzoyl peroxide-cobalt naphthenate; and the like.

  The amount of the radical polymerization initiator to be used is usually preferably 0.001 to 1 mol, particularly preferably 1 mol, per 1 mol of the total number of mols of the phenolic hydroxyl group-containing acrylic monomer (A) and the acrylic monomer (B). It is 0.01 to 0.1 mol.

<Solvent>
The solvent used in the present invention is not particularly limited as long as it can dissolve the raw materials and products and does not adversely affect the reaction. Specifically, aliphatic alcohols (methanol, ethanol, etc.), aromatic hydrocarbons (toluene, xylene, etc.), halogenated hydrocarbons (dichloromethane, chloroform, etc.), ethers (diethyl ether, dibutyl ether, tetrahydrofuran, etc.) ) And amides (N, N-dimethylformamide, N, N-dimethylacetamide, etc.), but a plurality of types may be used in combination.
The amount of the solvent used is not particularly limited as long as the raw materials and products can be dissolved. Usually, it is preferably 1 to 100 times, more preferably 3 to 30 times, particularly preferably 5 to 20 times, the total mass of the phenolic hydroxyl group-containing acrylic monomer (A) and the acrylic monomer (B). It is.

<Reaction conditions>
The acrylic copolymer of the present invention can be obtained by dissolving the phenolic hydroxyl group-containing acrylic monomer (A) and the acrylic monomer (B) in a solvent and adding a radical polymerization initiator. The reaction temperature may be any temperature at which the radical polymerization initiator can generate radicals and does not adversely affect the reaction, and is usually -10 to 150C, preferably 10 to 120C, and particularly preferably. 20-100 ° C. The reaction time is not particularly limited, but the reaction can usually be completed sufficiently in 0.5 to 20 hours. After completion of the reaction, the solvent can be removed and the synthesized acrylic copolymer can be purified and isolated.

<Adhesive composition>
The adhesive composition according to the present invention contains an acrylic copolymer. The adhesive composition may include an organic solvent and / or other components in addition to the acrylic copolymer. Examples of the organic solvent include aliphatic alcohols (eg, methanol and ethanol), aromatic hydrocarbons (eg, toluene and xylene), halogenated hydrocarbons (eg, dichloromethane and chloroform), and amides (eg, N, N-dimethylformamide). , N, N-dimethylacetamide, etc.), ketones (acetone, methyl ethyl ketone, etc.), esters (ethyl acetate, butyl acetate, etc.), ethers (ethylene glycol dimethyl ether, ethylene glycol diethyl ether, etc.), sulfoxide (dimethyl sulfoxide, etc.) It is. Other components are not particularly limited, but specific examples include silica, alumina, titania, calcium carbonate, talc, mica, diatomaceous earth, carbon fiber, graphite, and the like.
The content of the acrylic copolymer is preferably from 1 to 99% by mass, particularly preferably from 10 to 90% by mass, based on the adhesive composition (in terms of solid content excluding the organic solvent).
The amount of the other components is preferably from 99 to 1% by mass, particularly preferably from 90 to 10% by mass, based on the adhesive composition (in terms of solid content excluding the organic solvent).
The organic solvent is preferably adjusted so that the solid content concentration of the adhesive composition is 1 to 90% by mass, and particularly preferably adjusted to be 10 to 50% by mass.

  The acrylic copolymer or the adhesive composition can be applied on a substrate to form a coating film containing the acrylic copolymer on the substrate. The substrate is not particularly limited, but is, for example, metal, plastic, inorganic substance (for example, mortar, concrete and tile), wood, organic resin (for example, ABS resin, polycarbonate resin, polyimide resin, polyamide resin and polyester resin). . This coating shows good adhesion.

<Laminate>
The laminate according to the present invention has an adhesive layer obtained by curing an acrylic copolymer or an adhesive composition containing the acrylic copolymer, and a layer composed of a base material.
Hereinafter, embodiments of the laminate will be described, but those not particularly described may be the same as the embodiments of the adhesive composition.
An acrylic copolymer or an adhesive composition containing an acrylic copolymer is coated on a substrate (for example, a plastic substrate, an elastomer substrate, a civil engineering building substrate, a metal substrate, a glass substrate, etc.). By applying and curing the composition, a laminate having an adhesive layer and a layer composed of a base material can be obtained.
Examples of the plastic substrate include substrates made of polyester, polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyvinyl acetate, ABS resin, acrylic, polycarbonate, polyethylene terephthalate, nylon, and the like.
As the elastomer base material, for example, a base material made of natural rubber, styrene / butadiene rubber, isoprene rubber, butadiene rubber, chloroprene rubber, ethylene / propylene rubber, ethylene / propylene / diene rubber, urethane rubber, silicone rubber, fluorine rubber, etc. No.
Examples of the substrate for civil engineering and construction include substrates composed of concrete, mortar, tiles, and the like.
Examples of the metal substrate include a substrate made of aluminum, iron, stainless steel, and the like, and a substrate obtained by surface-treating these substrates.

  Next, specific embodiments of the present invention will be described with reference to Examples and Comparative Examples, but the scope of the present invention is not limited to these Examples.

(Adhesion strength)
The acrylic copolymer was dissolved using methyl ethyl ketone to prepare a solid content concentration of 30%. The coating amount on the mortar plate was set to an amount corresponding to 0.15 kg / m ² as a solid content. After coating, the coating was aged at 23 ° C. for one week, and the solvent was volatilized to form a coating film. Subsequently, the coating film and the jig for tension were adhered using a two-component epoxy resin, and the adhesion strength was measured with a tensile tester.

[Adhesive shear strength]
The acrylic copolymer was dissolved using methyl ethyl ketone to prepare a solid content concentration of 30%. A solid equivalent of 0.05 g is applied to the tip (25 × 12.5 mm) of a 100 × 25 × 1.6 mm SPCC-SB steel plate, dried at 23 ° C. for 1 hour, and then sandwiched between two steel plates. Fixed. After curing at 23 ° C. and 50% humidity for one week, the adhesive shear strength was measured by a tensile tester.

(Measurement of weight average molecular weight)
The weight average molecular weight of the acrylic copolymer was measured by GPC (gel permeation chromatography). The numerical value of the weight average molecular weight is a converted value using polystyrene.

[Synthesis Example 1: Synthesis of 4,5-bis (acrylamidomethyl) catechol]

  31.8 g (0.315 mol) of N-hydroxymethylacrylamide, 16.5 g (0.15 mol) of catechol, and 132 g of ethanol were added to a glass flask to form a uniform solution. After confirming the dissolution of the solid, 1.47 g (0.015 mol) of 98% sulfuric acid was added dropwise. Next, the reaction temperature was set to 80 ° C., and the reaction was performed at the same temperature for 5 hours. After the completion of the reaction, the reaction solution was cooled to 5 ° C., kept at the same temperature for 30 minutes, and the precipitated crystals were separated by filtration. The obtained residue was dried under reduced pressure in an oven at 50 ° C. to obtain 6.7 g of 4,5-bis (acrylamidomethyl) catechol, which is a phenolic hydroxyl group-containing acrylic monomer (A) (acquisition yield: 15. 3%). When the obtained crystal was evaluated by NMR analysis, it was confirmed that it was the target phenolic hydroxyl group-containing acrylic monomer (A). In addition, the filtrate removed by filtration was analyzed by HPLC to confirm that it contained a phenolic hydroxyl group-containing acrylic monomer (A) to which one acrylamidomethyl group was added in addition to 4,5-bis (acrylamidomethyl) catechol. Confirmed.

(NMR data of 4,5-bis (acrylamidomethyl) catechol)
1H NMR (400 MHz; DMSO-d6): δ 8.82 (2H, s), 8.41 (2H, t), 6.64 (2H, s), 6.26 (2H, q), 6.11 ( 2H, s), 5.60 (1H, q), 4.21 (4H, d)

(Conditions for HPLC analysis)
Column: Inertsil ODS-SP 3 μm 250 mm × 4.6 mm ID
Mobile phase; solution A: 0.1% phosphoric acid aqueous solution solution B: 0.1% phosphoric acid / acetonitrile = 2/8 (v / v)
Gradient program; solution A / solution B = 8/2 hold (0-10 minutes) → 10 → linear change to 2/8 in 20 minutes → 2/8 hold (20-30 minutes)
Flow rate: 1.0 mL / min Detector: UV 230 nm Column oven: Constant holding time around 40 ° C .: 4,5-bis (acrylamidomethyl) catechol: 8.3 min, 4- (acrylamidomethyl) catechol: 7.6 min

[Synthesis Example 2: Synthesis of 4,5-bis (acrylamidomethyl) catechol]
1.02 g (0.01 mol) of N-hydroxymethylacrylamide, 0.55 g (0.005 mol) of catechol, and 5 g of acetic acid were added to a glass flask to form a uniform solution. After confirming the dissolution of the solid, 0.5 g of Amberlyst 15 (H) (cation exchange resin, manufactured by Organo) was added, and the mixture was reacted at room temperature for 24 hours. After the completion of the reaction, quantitative analysis was performed by HPLC, and it was confirmed that 0.32 g of 4,5-bis (acrylamidomethyl) catechol, which is a phenolic hydroxyl group-containing acrylic monomer (A), was contained (reaction yield). Rate 22.9%).

[Example 1: Synthesis of acrylic copolymer]
In a glass flask, 1.4 g (0.005 mol) of 4,5-bis (acrylamidomethyl) catechol obtained in Synthesis Example 2, 6.4 g (0.05 mol) of butyl methacrylate, N, N-dimethyl 120 g of formamide was added to make a homogeneous solution. After confirming dissolution of the solid, 0.12 g (0.00075 mol) of 2,2'-azo (isobutyronitrile) was added. Next, the reaction temperature was set to 75 ° C., and the reaction was carried out at the same temperature for 16 hours. After the completion of the reaction, the resultant was cooled to room temperature, and the solvent was distilled off. 50 g of water was added to the obtained residue to precipitate a solid, and a solid was obtained by filtration. The solid was dissolved in 30 g of tetrahydrofuran, and the solid was reprecipitated by adding water again. The obtained solid was dried at 50 ° C. under reduced pressure to obtain 3.5 g of an acrylic copolymer. When the obtained solid was analyzed by GPC, the mass average molecular weight was 90,500.

[Example 2: Synthesis of acrylic copolymer]
In a glass flask, 1.4 g (0.005 mol) of 4,5-bis (acrylamidomethyl) catechol obtained in Synthesis Example 2, 8.9 g (0.045 mol) of 2-ethylhexyl methacrylate, N, N -120 g of dimethylformamide was added to make a homogeneous solution. After confirming dissolution of the solid, 0.12 g (0.00075 mol) of 2,2'-azo (isobutyronitrile) was added. Next, the reaction temperature was set to 75 ° C., and the reaction was carried out at the same temperature for 16 hours. After the completion of the reaction, the mixture was cooled to room temperature, and the solvent was distilled off using an evaporator. 50 g of water was added to the obtained residue to precipitate a solid, and a solid was obtained by filtration. The solid was dissolved in 30 g of tetrahydrofuran, and the solid was reprecipitated by adding water again. The obtained solid was dried at 50 ° C. under reduced pressure to obtain 5.0 g of an acrylic copolymer. When the obtained solid was analyzed by GPC, the mass average molecular weight was 67,800. Table 1 shows the results of the adhesive strength and the adhesive shear strength.

Comparative Example 1: Synthesis of Hydroxyl-Free Acrylic Copolymer
To a glass flask, 0.24 g (0.0015 mol) of N-benzylacrylamide, 2.68 g (0.0135 mol) of 2-ethylhexyl methacrylate, and 8.0 g of N, N-dimethylformamide were added, and a homogeneous solution was added. did. After confirming the dissolution of the solid, 5 mg (0.03 mmol) of 2,2′-azo (isobutyronitrile) was added. Next, the reaction temperature was set to 75 ° C., and the reaction was performed at the same temperature for 12 hours. After the completion of the reaction, the resultant was cooled to room temperature, and the solvent was distilled off. 5 g of tetrahydrofuran and 10 g of water were added to the obtained residue to separate into an oil layer and an aqueous layer, and the oil layer was recovered. The solvent was removed from the oil layer at 50 ° C. under reduced pressure to obtain 2.4 g of a hydroxyl group-free acrylic copolymer. When the obtained solid was analyzed by GPC, the mass average molecular weight was 9,700. Table 1 shows the results of the adhesive strength and the adhesive shear strength.

  Acrylic copolymers are used for coatings (coating materials) such as inks, paints, adhesives and pressure-sensitive adhesives, various mobile devices that require high appearance and high durability, films, building interior and exterior, and automobile interior and exterior. And the like, and molding applications (molding materials) such as cured moldings such as UV-curable lenses. Acrylic copolymers are particularly suitable as adhesives.

Claims (8)

A repeating unit derived from a phenolic hydroxyl group-containing acrylic monomer represented by the following formula (A):
Including a repeating unit derived from an acrylic monomer represented by the following formula (B):
Acrylic copolymer.

[In the formula (A), R ¹ is a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, m is 2 to 3, n is 1 to 4, and the sum of m and n is 3 to 6. is there. ]

[In the formula (B), R ² is a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and R ³ is a hydrogen atom, an alkyl group having 1 to 18 carbon atoms, an alkenyl group having 2 to 18 carbon atoms, or a carbon atom. It is an aromatic group of the formulas 6 to 20, and X is O or NH. ]   The molar ratio of the repeating unit derived from the phenolic hydroxyl group-containing acrylic monomer represented by the formula (A) to the repeating unit derived from the acrylic monomer represented by the formula (B) is 1:99 to 40: The acrylic copolymer according to claim 1, which has a molecular weight of 60.   3. The formula (A) according to claim 1, wherein the formula (A) includes a plurality of types of n repeating units, and a proportion of the repeating unit in which n is 2 or more is 10 mol% or more with respect to a total of all the repeating units. Acrylic copolymer.   3. The acrylic copolymer according to claim 1, wherein m is 2 and n is 2 to 4 in the formula (A). 4. In the formula (A), R ¹ is a hydrogen atom, in the formula (B), R ² is a hydrogen atom or a methyl group, and R ³ is a linear or branched alkyl having 1 to 18 carbon atoms. 5. The acrylic copolymer according to claim 1, wherein X is O. 6.   An adhesive composition comprising the acrylic copolymer according to claim 1.   A laminate comprising: an adhesive layer obtained by curing the acrylic copolymer according to claim 1; and a layer composed of a base material.   The method according to any one of claims 1 to 5, further comprising a step of copolymerizing the phenolic hydroxyl group-containing acrylic monomer (A) represented by the formula (A) and the acrylic monomer represented by the formula (B). The method for producing the acrylic copolymer according to the above.