JP2016216592A - Acrylic resin for adhesive and acrylic resin composition for adhesive comprising the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an acrylic resin that gives an adhesive that has excellent adhesion to various base materials, and is used for UV curing materials to accelerate a curing rate, and an acrylic resin composition for adhesive prepared therewith.SOLUTION: An acrylic resin composition for adhesive does not comprise a solvent or a plasticizer and is characterized in that in the presence of an addition cleavage-type chain transfer agent, an acrylic acid ester monomer mixture is polymerized and then reacted with a (meth) acrylic acid ester having an isocyanate group.SELECTED DRAWING: None

Description

  The present invention relates to an acrylic resin for adhesives and an acrylic resin composition for adhesives containing the same.

  Acrylic adhesive materials are superior to other materials such as rubber adhesives and silicone adhesives in adhesive performance such as adhesive strength and cohesive strength, and film resistance such as weather resistance, heat resistance, and solvent resistance. Widely used. Acrylic adhesive materials include solvent types based on an acrylic resin solution obtained by solution polymerization using a solvent as a medium, and aqueous systems based on an acrylic resin solution obtained by emulsion polymerization using water as a medium. There are types. In addition to these, a solventless type material that does not use a solvent has been proposed from the viewpoint of environmental considerations such as VOC (emission solvent regulations) in recent years. This solvent-free type can also comprehensively solve the problems of water-based types such as poor water resistance due to the effect of necessarily including an emulsifier. In particular, the useless type has been applied more and more because it does not require preliminary drying and saves energy.

  Adhesive applications include general-purpose adhesives, industrial adhesives such as adhesive tapes and processed products with adhesive layers, adhesion to semiconductor substrates, TVs, tablet PCs, smartphones, etc. And an optical adhesive used in the construction of electronic information terminals. In these applications, although there are various required characteristics, it is common that strong adhesiveness is required for the adhesive, and it can be used as a material for one type of other base material and without solvent. Some are more desirable.

  Cited Document 1 proposes a solvent-type acrylic resin that is a combination of a specific (meth) acrylic acid ester for use in optical pressure-sensitive adhesives. Although durability, whitening, and reworkability are good by using this solvent-type acrylic resin, there is a concern that strong adhesiveness cannot always be obtained for various substrates. As described in the examples of the cited document 1, the actual physical properties are considered to be indispensable to use a polyisocyanate or a silane coupling agent as a curing crosslinking component. Since it itself has no polymerizability and is a solvent type, it is considered to be an unsuitable technique for applications employing UV curing.

  On the other hand, Patent Document 2 uses an optical material containing a polymer having a (meth) acryl group having a specific structure as a constituent unit and having an ethylenically unsaturated group introduced into the side chain via a urethane bond or an amide bond. An optical waveguide has been proposed. Although this optical material is of a solvent type, it is a material that can be expected to exhibit physical properties particularly by UV curing because the polymer itself has an ethylenically unsaturated group that is a polymerization group. However, the adhesiveness is not described in the examples, and there is a concern that strong adhesiveness is not necessarily obtained for various substrates. Moreover, although the Example of the cited reference 2 shows the manufacture example which carries out addition reaction of methacrylic acid etc. after copolymerizing the monomer which has an isocyanate group to an acrylic resin, a highly reactive isocyanate group is a polymer side chain. There is a concern that the stability of the product will be very poor if it remains in the container.

  Cited Document 3 proposes an acrylic resin which is a solvent-free type suitable for heat curing and UV curing and has strong adhesiveness to various substrates, and a composition using the same. This technique is a solvent-free composition using a polymerizable acrylic resin and a chlorinated olefin resin having specific structural units. However, since it contains chlorine due to the chlorinated olefin resin and the structural component having a carboxyl group is included in the essential components of the polymerizable acrylic resin, the electrical properties are deteriorated and corrosive particularly in electronic materials. This is a concern.

JP 2005-314453 A JP 2009-175244 A JP 2014-196375 A

  The present invention achieves excellent adhesion performance to various substrates including difficult-to-adhere substrates that were difficult with the prior art without including acid components and chlorine components, and further, when used in UV curable materials, the curing rate. It is an object of the present invention to provide an acrylic resin that provides a pressure-sensitive adhesive that speeds up the process and an acrylic resin composition for an adhesive using the same.

（式（Ｉ)中、Ｒ¹は炭素数４〜２０のアルキル基、Ｒ²は炭素数６〜８の環状炭化水素基を１〜３個有する置換基、Ｒ³は下記一般式（ＩＩ）で表される２価の置換基、Ｒ⁴は炭素数２〜４のアルキレン基、Ｒ⁵は水素またはメチル基であり、ａ，ｂ，ｃ，ｄは１以上の実数である。

式（ＩＩ）中、Ｒ⁶は炭素数２〜４のアルキレン基、ｎは０〜５の整数である。） The acrylic resin for adhesives of the present invention has a structural unit represented by the following general formula (I), and the repeating units to which the repeating numbers a, b, c and d are attached are the structural units A, B, When C and D, the weight fraction of the structural unit A is 10 to 88.9% by weight, the weight fraction of the structural unit B is 10 to 50% by weight, and the weight fraction of the structural unit C is 1 to 30% by weight. And the weight fraction of the structural unit D is 0.1-10 weight%, It is characterized by the above-mentioned.

(In the formula (I), R ¹ is an alkyl group having 4 to 20 carbon atoms, R ² is a substituent having 1 to 3 cyclic hydrocarbon groups having 6 to 8 carbon atoms, and R ³ is the following general formula (II) Wherein R ⁴ is an alkylene group having 2 to ⁴ carbon atoms, R ⁵ is hydrogen or a methyl group, and a, b, c and d are 1 or more real numbers.

In formula (II), R ⁶ is an alkylene group having 2 to 4 carbon atoms, and n is an integer of 0 to 5. )

（式中、Ｒ¹は炭素数４〜２０のアルキル基である。）

（式中、Ｒ²は炭素数６〜８の環状炭化水素基を１〜３個有する置換基である。）

（式中、Ｒ³は前記一般式（ＩＩ）で表される２価の置換基である。）

（式中、Ｒ⁴は炭素数２〜４のアルキレン基、Ｒ⁵は水素またはメチル基である。） Moreover, the acrylic resin composition for adhesives is 30% by weight or more of the acrylic resin for adhesives represented by the general formula (I), and the monomer Am represented by the following general formula (III) , General formula (IV
70% by weight of a monomer mixture consisting of the monomer Bm represented by formula (V), the monomer Cm represented by formula (V) and the (meth) acrylate ester Em represented by formula (VI) It contains below.

(In the formula, R ¹ is an alkyl group having 4 to 20 carbon atoms.)

(In the formula, R ² is a substituent having 1 to 3 cyclic hydrocarbon groups having 6 to 8 carbon atoms.)

(In the formula, R ³ is a divalent substituent represented by the general formula (II).)

(In the formula, R ⁴ is an alkylene group having 2 to ⁴ carbon atoms, and R ⁵ is hydrogen or a methyl group.)

  According to the acrylic resin for adhesives of the present invention, PET, when cured with heat, UV, etc. by limiting the structural unit of the polymerizable acrylic resin without using a chlorinated olefin resin or the like, Good adhesiveness can be expressed on plastic substrates such as polycarbonate and polymethyl methacrylate, and also on olefin resin substrates such as polypropylene. Furthermore, since this acrylic resin for adhesives does not contain an acid component or a chlorine component, it can be suitably used for electronic materials and optical materials.

  Furthermore, the solvent-free type acrylic resin composition for adhesives comprising the adhesive adhesive resin can be suitably used for each adhesive application. Specifically, by partially polymerizing a mixture of acrylate monomer Am, Bm and Cm in the presence of an addition-cleavage chain transfer agent without solvent and plasticizer, acrylic resin and acrylate ester After obtaining a mixture of the monomers Am, Bm and Cm in a lump, the (meth) acrylic acid ester Em having an isocyanate group can be reacted to produce an acrylic resin composition for an adhesive.

（式（Ｉ)中、Ｒ¹は炭素数４〜２０のアルキル基、Ｒ²は炭素数６〜８の環状炭化水素基を１〜３個有する置換基、Ｒ³は下記一般式（ＩＩ）で表される２価の置換基、Ｒ⁴は炭素数２〜４のアルキレン基、Ｒ⁵は水素またはメチル基であり、ａ，ｂ，ｃ，ｄは１以上の実数である。

式（ＩＩ）中、Ｒ⁶は炭素数２〜４のアルキレン基、ｎは０〜５の整数である。） The acrylic resin for adhesives of the present invention has a structural unit represented by the following general formula (I), and the repeating units to which the repeating numbers a, b, c and d are attached are the structural units A, B, When C and D, the weight fraction of the structural unit A is 10 to 88.9% by weight, the weight fraction of the structural unit B is 10 to 50% by weight, and the weight fraction of the structural unit C is 1 to 30% by weight. And the weight fraction of the structural unit D is 0.1 to 10 weight%.

(In the formula (I), R ¹ is an alkyl group having 4 to 20 carbon atoms, R ² is a substituent having 1 to 3 cyclic hydrocarbon groups having 6 to 8 carbon atoms, and R ³ is the following general formula (II) Wherein R ⁴ is an alkylene group having 2 to ⁴ carbon atoms, R ⁵ is hydrogen or a methyl group, and a, b, c and d are 1 or more real numbers.

In formula (II), R ⁶ is an alkylene group having 2 to 4 carbon atoms, and n is an integer of 0 to 5. )

In this specification, the repeating units to which the repeating numbers a, b, c and d described in the general formula (I) are attached are referred to as structural units A, B, C and D, respectively. Among these, the structural units A, B and C can be obtained by radical polymerization of monomers Am, Bm and Cm having the respective structural characteristics in the presence of an addition-cleavage chain transfer agent. The structural unit D is obtained by subjecting the structural unit C to an addition reaction of (meth) acrylic ester Em having an isocyanate group. By using an addition-cleavage chain transfer agent typified by α-methylstyrene dimer when manufacturing this acrylic resin for adhesives, industrially safe solvent-free polymerization is possible. The obtained acrylic resin for adhesives and the resin composition containing the adhesive acrylic resin can make the curing rate of the adhesives very fast.

（式中、Ｒ¹は炭素数４〜２０のアルキル基である。） In the present invention, the monomer Am is represented by the following general formula (III).

(In the formula, R ¹ is an alkyl group having 4 to 20 carbon atoms.)

In the general formulas (I) and (III), R ¹ is an alkyl group having 4 to 20 carbon atoms,
A linear or branched alkyl group having 8 to 10 carbon atoms is preferred. That is, the structural unit A is obtained by polymerizing the acrylate monomer Am represented by the general formula (III). Examples of the acrylate monomer Am having an alkyl group having 4 to 20 carbon atoms include normal butyl acrylate, isobutyl acrylate, tertiary butyl acrylate, normal octyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate, Examples include acrylic acid alkyl ester monomers such as isononyl acrylate, isodecyl acrylate, dodecyl acrylate (lauryl acrylate), tridecyl acrylate, stearyl acrylate, and isostearyl acrylate. These monomers may be used alone or as a mixture of two or more. Among them, R ¹ is preferably a linear or branched alkyl group having 8 to 10 carbon atoms from the balance of adhesive properties, boiling point, and the like. In consideration of availability, acrylic acid 2 is used as monomer Am. -Ethylhexyl is preferred.

The structural unit A is 10% in 100% by weight of the acrylic resin for adhesives represented by the general formula (I).
It is -88.9 weight%, Preferably it is 30-73.9 weight%, More preferably, it is 47-78.9 weight%. If the structural unit A is less than 10% by weight, the glass transition temperature of the acrylic resin for adhesives increases, and the tackiness may be impaired. If the structural unit A exceeds 88.9% by weight, the cohesive force of the acrylic resin for adhesives is insufficient, and the tackiness may be impaired.

（式中、Ｒ²は炭素数６〜８の環状炭化水素基を１〜３個有する置換基である。） In the present invention, the structural unit B in the general formula (I) is obtained by polymerizing the monomer Bm. Monomer Bm is represented by the following general formula (IV).

(In the formula, R ² is a substituent having 1 to 3 cyclic hydrocarbon groups having 6 to 8 carbon atoms.)

In the above general formulas (I) and (IV), R ² represents a substituent having 1 to 3 cyclic hydrocarbon groups having 6 to 8 carbon atoms, preferably a cyclic hydrocarbon group having no double bond. It is a substituent having three. That is, the structural unit B is obtained by polymerizing the acrylate monomer Bm represented by the general formula (IV). Examples of the acrylate monomer Bm having 1 to 3 cyclic hydrocarbon groups having 6 to 8 carbon atoms include cyclohexyl acrylate, phenyl acrylate, naphthyl acrylate, dicyclopentanyl acrylate, and dicyclopentenyl acrylate. And acrylate monomers such as isobornyl acrylate. These monomers may be used alone or in a mixture of two or more. Among them, the cyclic hydrocarbon group of R ² is preferably one having no double bond because of the reason that the inhibition of curing is small when considering use in UV curing. Further, considering availability, cyclohexyl acrylate and dicyclopentanyl acrylate are preferable as the monomer Bm.

The structural unit B is 10% in 100% by weight of the acrylic resin for adhesives represented by the general formula (I).
-50 wt%, preferably 15-45 wt%, more preferably 20-40 wt%. If the structural unit B is less than 10% by weight, the cohesive force of the acrylic resin for adhesives is insufficient, and the tackiness may be impaired. On the other hand, if the structural unit B is more than 50%, the glass transition temperature rises and the adhesiveness may be impaired.

（式中、Ｒ³は下記一般式（ＩＩ）で表される２価の置換基である。）

（式（ＩＩ）中、Ｒ⁶は炭素数２〜４のアルキレン基、ｎは０〜５の整数である。） In the present invention, the structural unit C in the general formula (I) is obtained by polymerizing the monomer Cm. The monomer Cm is represented by the following general formula (V).

(In the formula, R ³ is a divalent substituent represented by the following general formula (II).)

(In Formula (II), R ⁶ is an alkylene group having 2 to 4 carbon atoms, and n is an integer of 0 to 5)

In the general formulas (I) and (V), R ³ is a divalent substituent represented by the general formula (II). That is, the structural unit C is obtained by polymerizing the acrylate monomer Cm having a hydroxyl group represented by the general formula (V). Examples of the acrylate monomer Cm include acrylic acid alkyl esters such as 2-hydroxyethyl acrylate, 3-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, and ε-caprolactone-modified (n = 1 to 5) acrylate. An example is a mer. These monomers may be used alone or in a mixture of two or more. Among them, the acrylic ester monomer Cm having a hydroxyl group represented by the general formula (V) is 4-hydroxybutyl acrylate, ε-, because it has good reactivity and is easy to lower the glass transition temperature in a liquid state. Caprolactone modified (n = 2) acrylate is desirable.

The structural unit C is 1 to 30% by weight, preferably 1 to 20% by weight, more preferably 1 to 10% by weight in 100% by weight of the acrylic resin (I) for adhesives represented by the general formula (I). %. When the structural unit C is less than 1% by weight, the cohesive force of the acrylic resin (I) for adhesives is insufficient, and the tackiness may be impaired. On the other hand, if the structural unit C exceeds 30% by weight, the hardness increases due to an increase in hydrogen bonding property, and the adhesiveness may be impaired.

（式中、Ｒ⁴は炭素数２〜４のアルキレン基、Ｒ⁵は水素またはメチル基である。） In the present invention, the structural unit D in the general formula (I) is formed by copolymerizing the structural unit C, and then the addition reaction of the (meth) acrylic acid ester E having an isocyanate group is performed on the hydroxyl group of the structural unit C. Is obtained. The (meth) acrylic ester E is represented by the following general formula (VI).

(In the formula, R ⁴ is an alkylene group having 2 to ⁴ carbon atoms, and R ⁵ is hydrogen or a methyl group.)

In the general formulas (I) and (VI), R ⁴ is an alkylene group having 2 to 4 carbon atoms, preferably an alkylene group having 2 to 3 carbon atoms. R ⁵ is hydrogen or a methyl group. As the (meth) acrylic acid ester E having an isocyanate group, 2-isocyanatoethyl acrylate, 3-isocyanatopropyl acrylate, 4-isocyanatobutyl acrylate, 2-isocyanatoethyl methacrylate, 3-methacrylic acid 3- Illustrative are (meth) acrylic acid ester monomers of isocyanate propyl and 4-isocyanatobutyl methacrylate. These (meth) acrylic acid esters may be used alone or as a mixture of two or more. Among these, acrylic acid esters are desirable because of their high curing speed, and 2-isocyanatoethyl acrylate and 2-isocyanatoethyl methacrylate are preferred in view of availability.

The structural unit D is 0.1% in 100% by weight of the acrylic resin for adhesives represented by the general formula (I).
1 to 10% by weight, preferably 0.1 to 5% by weight, more preferably 0.1 to 3% by weight. When the structural unit D is less than 0.1% by weight, the acrylic resin (I) for adhesives is hardened and the tackiness may be impaired. When the structural unit D is more than 10% by weight, the hardness of the cured product is increased and the adhesiveness may be impaired.

The acrylic resin for adhesives represented by the general formula (I) of the present invention has a weight average molecular weight (Mw).
Is preferably 100,000 to 300,000, more preferably 100,000 to 250,000, and even more preferably 100,000 to 200,000. The polydispersity represented by the ratio Mw / Mn of the weight average molecular weight (Mw) and the number average molecular weight (Mn) is preferably 2.0 to 5.0, more preferably 2.0 to 4.5, Preferably it is 2.0-4.0. When the weight average molecular weight (Mw) is less than 100,000, the cohesive force is insufficient and the adhesive performance tends to be impaired. On the other hand, when the weight average molecular weight (Mw) exceeds 300,000, the viscosity of the resulting solventless composition tends to increase and coating becomes difficult. If the polydispersity Mw / Mn of the molecular weight is less than 2.0, tackiness (initial tackiness) tends to be impaired. On the other hand, when the polydispersity Mw / Mn of the molecular weight exceeds 5.0, the cohesive force is lowered and the adhesive performance tends to be impaired.

The acrylic resin for adhesives represented by the general formula (I) of the present invention has a glass transition temperature of preferably −60 to 0 ° C., more preferably −55 to −10 ° C., still more preferably −50 to − It is good at 20 degreeC. When the glass transition temperature is less than −60 ° C., the cohesive force is insufficient, and when the glass transition temperature exceeds 0 ° C., the hardness of the cured product increases and the tackiness tends to be impaired. In this specification, the glass transition temperature of the acrylic resin for adhesives represented by the general formula (I) can be calculated by the FOX formula based on the sum of the structural units A, B, and C. Here, as the glass transition temperature of the homopolymer of the acrylate monomer Am, Bm, Cm applied to the FOX formula, a value published by the manufacturer of each monomer can be adopted.

In the present invention, the acrylic resin for adhesives represented by the general formula (I) can be used alone as an adhesive material. Moreover, it can also be used for an adhesive material as an acrylic resin composition for adhesives containing the acrylic resin for adhesives, and an acrylate monomer mixture.

The acrylic ester monomer mixture is a monomer Am, Bm, Cm and Em for forming the structural units A, B, C and D in the acrylic resin for adhesives represented by the general formula (I) It is a mixture of If these monomers are monomers for forming the structural units A, B, C and D in the acrylic resin for adhesives represented by the general formula (I), the monomers Am, Bm , Cm and Em may not necessarily be the same as the constituent weight ratio of the structural units A, B, C and D.

The acrylic resin composition for adhesives of the present invention is 30 to 80% by weight, preferably 40 to 75% by weight, more preferably 50 to 50% by weight of the acrylic resin for adhesives represented by the general formula (I). It is preferable to contain 70% by weight, and at the same time, the composition of the acrylate monomer Am, Bm, Cm and Em is 20 to 70% by weight, preferably 25 to 60% by weight, more preferably 30 to 50% by weight. desirable. When the mixture of the acrylic resin for adhesives represented by the general formula (I) and the acrylic ester monomers Am, Bm, Cm and Em is within the above-described composition range, the pressure-sensitive adhesive performance and the curing rate are lowered. Tend to.

In this invention, the manufacturing method of the acrylic resin for adhesives represented by general formula (I) can be obtained by radical polymerization using an addition cleavage type chain transfer agent. This production method is particularly desirable because it allows solvent-free polymerization and further tends to increase the curing rate of the resulting acrylic resin.

Examples of the addition-cleavage chain transfer agent used in the method for producing an acrylic resin for adhesives according to the present invention include α-methylstyrene dimer, 2-cyano-2-propylbenzodithionate, cyanomethyldodecyltrithiocarbonate, bis Examples include (thiobenzoyl) disulfide. Among these, α-methylstyrene dimer represented by the following chemical formula (VII), that is, 2,4-diphenyl-4-methyl-1-pentene, is easily available and inexpensive, and thus can be particularly preferably used.

  The use amount of the addition-cleavage type chain transfer agent of the present invention is preferably 0.1 to 10% by weight, more preferably 0.1 to 5% by weight based on the set weight of the acrylic resin for the adhesive to be polymerized. %, More preferably 0.3 to 3% by weight. If the amount of addition-cleavage chain transfer agent used is less than 0.1% by weight, the polymerization reaction rate becomes uncontrollable and solvent-free polymerization tends to be impossible. If the amount of addition-cleavage chain transfer agent used exceeds 10% by weight, the polymerization reaction rate becomes extremely slow, so that the productivity tends to be remarkably impaired.

The method for producing an acrylic resin for adhesives represented by the general formula (I) in the present invention uses radical polymerization using an addition-cleavage chain transfer agent, suitable molecular weight and polydispersity, and glass transition. If it superposes | polymerizes so that temperature may satisfy | fill the said range, it will not specifically limit. In consideration of obtaining a solvent-free composition or an acrylic resin alone in a safe and simple manner, it is preferably obtained by solvent-free polymerization using living radical polymerization. Specifically, a polymerization initiator is added to a mixture of acrylic ester monomers Am, Bm and Cm and an addition-cleavage chain transfer agent to start bulk polymerization, and any amount or all amount is polymerized. A partial polymer or polymer of units A, B and C is obtained. Then, by reacting the hydroxyl group of the structural unit C with the (meth) acrylic acid ester monomer Em having an isocyanate group, the acrylic resin for acrylic adhesive and the acrylic acid ester represented by the general formula (I) A mixture of monomer mixtures Am, Bm, Cm and Em, or an acrylic resin for adhesives represented by the general formula (I) can be produced.

The acrylic resin for adhesives represented by the general formula (I) or the acrylic resin for adhesives represented by the general formula (I) and acrylate monomers Am, Bm, Cm and Em The acrylic resin composition for adhesives composed of the above mixture exhibits adhesiveness by being cured by a polymerization reaction. The curing method is not particularly limited, but a method of adding a polymerization initiator that generates radicals by heat, such as 2,2′-azobis (isobutyronitrile), dibenzoyl peroxide, and curing by heating, benzophenone, 1 Examples include a method of adding a polymerization initiator that absorbs ultraviolet rays such as -hydroxy-cyclohexyl-phenyl-ketone and 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, and curing by UV irradiation. These methods can be used alone or in combination. In addition to the radical polymerization initiator, cationic polymerization initiators and anionic polymerization initiators can be used as those capable of initiating the polymerization reaction.

  The details of the present invention will be described in the following examples, but the acrylic resin for adhesives and the acrylic resin composition for adhesives of the present invention are not limited to these examples.

  In the following examples and comparative examples, the measurement method, evaluation method, and the like were as follows. Moreover, the percentage (%) represents weight% unless otherwise specified.

1) Polymerization conversion rate (unit:%)
As the polymerization conversion rate when the acrylic resin was polymerized, the heating residue (%) was measured according to JIS K 5407: 1997. This polymerization conversion rate was defined as the concentration (%) of the polymer (acrylic resin) in the acrylic resin composition. However, the heating conditions were a temperature of 140 ° C. and a time of 30 minutes.

2) Concentration of each monomer and monomer mixture (unit:% by weight)
Using an acrylic resin composition as a sample, it was measured by liquid chromatography (manufactured by SIMADZU) equipped with a reverse phase column using acetonitrile and 0.02M phosphoric acid aqueous solution as an eluent. Each monomer was quantified by an external standard method using a calibration curve obtained by measuring the monomers Am, Bm, Cm and Em under the same conditions, and the value was determined for each monomer Am, Bm, Cm and Em concentrations (%) were used. The total of the obtained monomers Am, Bm, Cm and Em was taken as the monomer mixture concentration (%) in the acrylic resin composition.

3) Concentration of each structural unit of acrylic resin and polymer concentration (unit: wt%)
Charge weights of monomers Am, Bm, Cm and Em from which the respective structural units A, B, C and D are derived, and monomers Am, Bm in the acrylic resin composition determined in 2) corresponding to each Based on the weight calculated from the content concentration of C, Cm and Em (unreacted monomer concentration), the value calculated as follows was used as the concentration (%) of each structural unit A, B, C and D. Here, when there were a plurality of types in each structural unit, each was calculated and added up.
Constituent unit A concentration (%) = preparation concentration of monomer Am—Concentration of monomer A in acrylic resin composition Constituent unit B concentration (%) = preparation concentration of monomer Bm—in acrylic resin composition Monomer Bm Concentration Unit C Concentration (%) = [Monomer Cm Feeding Concentration−Monomer Em Feeding Concentration and Equimolar Monomer Cm Concentration] —Simple Amount in Acrylic Resin Composition Concentration unit of body Cm Concentration unit D concentration (%) = [preparation concentration of monomer Em + concentration of monomer Cm equimolar to preparation concentration of monomer Em] -monomer Em in the acrylic resin composition Concentration of

4) Glass transition temperature of polymer (unit: ° C)
The value calculated using the FOX equation on the basis of the total charged weight of monomers Am, Bm, and Cm was taken as the glass transition temperature of the polymer. Here, as the glass transition temperature of the homopolymer of each acrylate monomer applied to the FOX formula, the value published by the manufacturer of each monomer was adopted. The following values are used for the glass transition temperatures of the monomers in Examples and Comparative Examples.
Butyl acrylate -55 (℃)
2-ethylhexyl acrylate -63 (° C)
Isononyl acrylate -58 (℃)
Lauryl acrylate 15 (℃)
Ethyl acrylate -24 (℃)
Methyl methacrylate 105 (℃)
Cyclohexyl acrylate 15 (° C)
Cyclohexyl methacrylate 66 (° C)
Dicyclopentanyl acrylate 120 (° C)
2-hydroxyethyl acrylate -15 (° C)
2-hydroxyethyl methacrylate 55 (° C)
4-hydroxybutyl acrylate -32 (° C)
PLACCEL FA-2D -40 (° C)

5) Weight average molecular weight (Mw) / polydispersity (Mw / Mn)
The weight average molecular weight (Mw) and number average molecular weight (Mn) of the acrylic resin were determined by gel permeation chromatography (GPC) “HLC-8220GPC” (manufactured by Tosoh Corporation), and 0.025 M phosphoric acid-tetrahydrofuran as an eluent. Measured using the solution. The number average molecular weight (Mn) and the weight average molecular weight (Mw) were calculated in terms of standard polystyrene. The polydispersity (Mw / Mn) was determined by dividing the weight average molecular weight by the number average molecular weight.

6) Curing method The acrylic resins and acrylic resin compositions obtained in the examples and comparative examples were cured by the following methods to evaluate curability, transparency, and tackiness. Curing of the acrylic resin and the acrylic resin composition was performed by UV curing. As a polymerization initiator, 1 g of 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (BASF Japan's Lucillin TPO) was blended with 100 g of acrylic resin or acrylic resin composition, and stirred and mixed until completely dissolved. . This was adjusted to an arbitrary substrate and thickness, and cured with a UV irradiation machine CS30R1-1 (GS NIPPON DENCHI high-pressure mercury lamp) under the conditions of irradiation intensity of 100 mW / cm ² and integrated light quantity of 500 mJ / cm ² . .

7) Evaluation of curability: Curing conversion rate (unit:%)
An acrylic resin and an acrylic resin composition were used as samples, and the curing conversion rate (%) when UV-cured under the conditions of an irradiation intensity of 100 mW / cm ² and an integrated light amount of 500 mJ / cm ^{2 was} defined as curability. Curing conversion rate was measured by measuring the height of the double bond-derived peak (810 cm ⁻¹ ) with FT-IR before and after UV curing under the above conditions, and the double bond of the sample (adhesive material) before curing. The peak height of the double bond of the sample after curing with respect to the peak height was compared, and the disappearance percentage due to curing was defined as the curing conversion rate (%).
Since it can be judged that the curing conversion rate is higher as the curing conversion rate is higher in the curing under the same conditions, 97% or more was determined to be acceptable in the evaluation of this example and the comparative example.

8) Evaluation of transparency: total light transmittance (unit:%) / haze A sample (with a thickness of 230 μm on two 1 mm-thick float glass (JIS R 3202 standard: manufactured by Partec Co., Ltd.)) An acrylic resin or an acrylic resin composition) and a UV cured product were used as test pieces. For the measurement, a haze meter NDH2000 (manufactured by Nippon Denshoku Industries Co., Ltd.) was used, and it was based on the JIS K 7136 standard with a D65 light source. The measured value was measured using one float glass as a blank sample, and the total light transmittance (%) and haze were determined.
It can be determined that the higher the total light transmittance and the lower the haze, the higher the transparency. For this reason, in evaluation of a present Example and a comparative example, the total light transmittance determined that 98.0 (%) or more and haze 0.5 or less were determined to be a pass.

9) Evaluation of adhesiveness: Peel strength (unit: N / mm2)
According to JIS Z 0237, 180 ° peeling was measured at a speed of 300 (mm / min). A sample cured product having a thickness of 100 (μm) and a width of 25 (mm) cured on a PET film was attached to a substrate with a 2 kg roller to obtain a test piece. The following four types of base materials were used for the test.
Float glass (JIS R 3202 standard: manufactured by Partec)
Polypropylene (JIS K 6921 standard: manufactured by Partec)
Polycarbonate (JIS K 6735 standard: manufactured by Partec)
Polymethyl methacrylate (JIS K 6717 standard: manufactured by Partec)
It can be determined that the higher the peel strength, the higher the adhesive strength of the cured sample, and 5 (N / mm ² ) or more was determined to be acceptable in the evaluation of this example and the comparative example.

Example 1
In a 0.5 L four-necked flask having a nitrogen gas inlet tube, a reflux condenser, a stirring device, and a charging port, 78.0 g of 2-ethylhexyl acrylate, 20.0 g of dicyclopentanyl acrylate, 4-hydroxybutyl acrylate 2 g of α-methylstyrene dimer (2.0 g) was charged and stirred while bubbling with nitrogen gas, and the temperature of the mixture was adjusted to 50 ° C. Next, 1.2 g of 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile) (“V-70” manufactured by Wako Pure Chemical Industries, Ltd.) was added. After reacting for 2 hours while maintaining the temperature at 50 ° C., the temperature was raised to 85 ° C., and when the polymerization conversion reached about 98%, the supply air in the flask was switched from nitrogen to air and p− The reaction was stopped by adding 0.05 g of methoxyphenol. Next, 0.5 g of 2-isocyanatoethyl acrylate and 0.05 g of diisopropylethylamine were added, stirred at 95 ° C., and reacted until the peak of the isocyanate group (2260 cm ⁻¹ ) in FT-IR disappeared. The acrylic resin composition of Example 1 was obtained.

Examples 2-11
As in Example 1, except that the types and amounts of monomers Am, Bm, Cm and Em, the amounts of addition-cleavage chain transfer agent and polymerization initiator used, and the polymerization conversion ratio were changed as shown in Table 1. It produced and the acrylic resin composition of Examples 2-11 was obtained.

  The charge composition ratios in the above examples are shown in Table 1. The results of composition analysis of the obtained acrylic resin composition are shown in Table 2. Table 3 shows the results of evaluating the curing characteristics, transparency, and adhesive characteristics of the cured product of the acrylic resin composition.

Comparative Example 1
100 g of propylene glycol monomethyl ether acetate was charged into a 0.5 L four-necked flask having a nitrogen gas inlet tube, a reflux condenser, a stirrer, and a charging port, and the temperature was adjusted to 80 ° C. while agitating nitrogen. Then, 76.0 g of 2-ethylhexyl acrylate, 22.0 g of dicyclopentanyl acrylate, 2 g of 4-hydroxybutyl acrylate, and 0.2 g of 2,2′-azobis (isobutyronitrile) were added dropwise over 3 hours. After stirring for 1 hour, the temperature was adjusted to 95 ° C., 0.05 g of 2,2′-azobis (isobutyronitrile) was added 4 times every 30 and then stirred for 2 hours. Next, the supply air in the flask was changed from nitrogen to air, 0.4 g of 2-isocyanatoethyl acrylate and 0.04 g of diisopropylethylamine were added, and the mixture was stirred at 95 ° C., and an isocyanate group (2260 cm −1) in FT-IR was added. The polymer of Comparative Example 1 was obtained in the form of a 50% solution.

  200 g of this 50% polymer solution was put into 20 L of water adjusted to 80 ° C. and stirred for 1 hour. Thereafter, the same amount of water was replaced five times and this was repeated. The obtained polymer was put into a vacuum dryer and dried at 90 ° C. for 2 days to obtain an acrylic resin of Comparative Example 1.

Comparative Example 2
A polymer composition having the same composition as Comparative Example 1 was synthesized in the same manner as Comparative Example 1 except that the monomer Em (2-isocyanatoethyl acrylate) was not used, and an acrylic resin of Comparative Example 2 was obtained.

Comparative Examples 3-4
In the acrylic resin composition having the same composition as in Example 4, except that the amount of the monomer Em (2-isocyanatoethyl acrylate) used was changed as shown in Table 4, it was synthesized in the same manner as in Example 1 and compared. The acrylic resin composition of Examples 3-4 was obtained.

Comparative Examples 5-12
A polymer composition having the same composition as in Example 4, except that the types and / or charge amounts of monomers Am, Bm, and Cm were changed as shown in Table 4, and were synthesized in the same manner as in Example 1, and Comparative Example 5 to 12 polymer compositions were obtained.

  The charge composition ratios in the above comparative examples are shown in Table 4. Table 5 shows the results of composition analysis of the obtained acrylic resin and acrylic resin composition. Table 6 shows the results of evaluating the curing characteristics, transparency, and adhesive properties of the cured products of the acrylic resin and the acrylic resin composition.

  As in Examples 1 to 11, the acrylic resin composition having the specific structural unit of the present invention has a very good balance in terms of curability, transparency, and tackiness, and is generally considered to be difficult to adhere. It turns out that it has favorable adhesiveness in the various base material containing a polypropylene.

  On the other hand, an acrylic resin synthesized without using an addition-cleavage chain transfer agent as in Comparative Example 1, an acrylic resin or an acrylic resin composition having no structural unit D as in Comparative Examples 2 and 3, and Comparative Examples 10 to 12 Thus, it can be seen that the acrylic resin composition in which the methacrylic acid ester is introduced into the structural unit has lower curability than the examples.

  Moreover, from the evaluation results of Comparative Examples 4 to 7 and 11 to 12, it can be seen that the types, the amounts used, and the glass transition temperatures of the constituent components B and C have an appropriate range from the viewpoint of adhesiveness to various substrates. .

Claims (14)

When the repeating unit having the structural unit represented by the following general formula (I) and having the repeating numbers a, b, c and d is designated as the structural units A, B, C and D, the weight of the structural unit A The fraction is 10 to 88.9% by weight, the weight fraction of the structural unit B is 10 to 50% by weight, the weight fraction of the structural unit C is 1 to 30% by weight, and the weight fraction of the structural unit D is 0.1. An acrylic resin for adhesives, characterized in that the content is 10% by weight.

(In the formula (I), R ¹ is an alkyl group having 4 to 20 carbon atoms, R ² is a substituent having 1 to 3 cyclic hydrocarbon groups having 6 to 8 carbon atoms, and R ³ is the following general formula (II) Wherein R ⁴ is an alkylene group having 2 to ⁴ carbon atoms, R ⁵ is hydrogen or a methyl group, and a, b, c and d are 1 or more real numbers.

In formula (II), R ⁶ is an alkylene group having 2 to 4 carbon atoms, and n is an integer of 0 to 5. )   The acrylic resin for adhesives according to claim 1, wherein the weight average molecular weight (Mw) is 100,000 to 300,000 and the polydispersity (Mw / Mn) of the molecular weight is 2.0 to 5.0.   The acrylic resin for adhesives according to claim 1 or 2, wherein the glass transition temperature is -60 to 0 ° C. Monomer Am represented by the following general formula (III), monomer Bm represented by the general formula (IV),
And an acrylate polymer obtained by radical polymerization of the monomer Cm represented by the general formula (V) in the presence of an addition-cleavage chain transfer agent, an isocyanate represented by the following general formula (VI) The acrylic resin for adhesives according to any one of claims 1 to 3, which is obtained by reacting a (meth) acrylic acid ester Em having a group.

(In the formula, R ¹ is an alkyl group having 4 to 20 carbon atoms.)

(In the formula, R ² is a substituent having 1 to 3 cyclic hydrocarbon groups having 6 to 8 carbon atoms.)

(In the formula, R ³ is a divalent substituent represented by the general formula (II).)

(In the formula, R ⁴ is an alkylene group having 2 to ⁴ carbon atoms, and R ⁵ is hydrogen or a methyl group.) R ¹ is a linear or branched adhesive Acrylic resin according to any one of claims 1 to 4 is an alkyl group having 8 to 10 carbon atoms. The acrylic resin for adhesives according to any one of claims 1 to 5, wherein R ² is at least one selected from a cyclohexyl group and a dicyclopentanyl group. In general formula (I), the structural unit does not have a carboxy group, The acrylic resin for adhesives in any one of Claims 1-6 characterized by the above-mentioned.   The acrylic resin for adhesives according to any one of claims 1 to 7, which is used for an electronic material.   The acrylic resin for adhesives according to any one of claims 1 to 7, which is used for an optical material. 30-80% by weight acrylic resin for adhesives represented by the following general formula (I), monomer Am represented by the following general formula (III), single amount represented by the general formula (IV) Body Bm, general formula (V)
An acrylic resin composition for adhesives containing 20 to 70% by weight of a monomer mixture composed of a monomer Cm represented by formula (VI) and a (meth) acrylic acid ester Em represented by the general formula (VI).

(In the formula (I), R ¹ is an alkyl group having 4 to 20 carbon atoms, R ² is a substituent having 1 to 3 cyclic hydrocarbon groups having 6 to 8 carbon atoms, and R ³ is the following general formula (II) Wherein R ⁴ is an alkylene group having 2 to ⁴ carbon atoms, R ⁵ is hydrogen or a methyl group, and a, b, c and d are 1 or more real numbers.

In formula (II), R ⁶ is an alkylene group having 2 to 4 carbon atoms, and n is an integer of 0 to 5. )

(In the formula, R ¹ is an alkyl group having 4 to 20 carbon atoms.)

(In the formula, R ² is a substituent having 1 to 3 cyclic hydrocarbon groups having 6 to 8 carbon atoms.)

(In the formula, R ³ is a divalent substituent represented by the general formula (II).)

(In the formula, R ⁴ is an alkylene group having 2 to ⁴ carbon atoms, and R ⁵ is hydrogen or a methyl group.)   Contains no solvent or plasticizer. In the presence of an addition-cleavage chain transfer agent, the monomer mixture consisting of the monomer Am, the monomer Bm and the monomer Cm is partially polymerized, and then the (meth) acrylic acid ester Em is reacted. The acrylic resin composition for adhesives according to claim 10, wherein the acrylic resin composition is obtained.   The acrylic resin composition for adhesives according to claim 10 or 11, which does not contain an organic acid and an inorganic acid as components.   It is an object for electronic materials, The acrylic resin composition for adhesives in any one of Claims 10-12.   The acrylic resin composition for adhesives according to any one of claims 10 to 12, which is used for optical materials.