JP2017218599A - Adhesive composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive composition containing an acrylic block copolymer which has no bleeding and is excellent in transparency, tackiness and thermal stability.SOLUTION: An adhesive composition contains: 100 parts by mass of (i) an acrylic triblock copolymer which has one polymer block (B) formed of two polymer blocks (A1) and (A2) formed of a methacrylic acid ester unit and an acrylate unit, where the acrylate unit constituting the polymer block (B) is formed of an acrylate (1) unit represented by general formula (1): CH=CH-COOR, (in general formula (1), Rrepresents an organic group having 4-6 carbon atoms) and an acrylate (2) unit represented by general formula (2): CH=CH-COOR, (in general formula (2), Rrepresents an organic group having 7 to 12 carbon atoms); and 1-500 pts.mass of (ii) an acrylic diblock copolymer (II).SELECTED DRAWING: None

Description

  The present invention relates to an adhesive composition containing an acrylic block copolymer suitable for an adhesive or the like.

It has been conventionally known that an acrylic block copolymer or a composition containing an acrylic block copolymer is used as an adhesive.
For example, an adhesive composition comprising an acrylic block copolymer, a tackifier resin, and a plasticizer is known (see Patent Documents 1 and 2).

JP-A-2006-44203 International Publication No. 2016/027767

  Since the pressure-sensitive adhesive and pressure-sensitive adhesive composition described in the above-mentioned patent documents have a plasticizer, they are stored for a long time after being made into a pressure-sensitive adhesive tape and pasted on an adherend such as paper. There is a problem that the plasticizer easily moves to the adherend side, and there is still room for improvement.

  An object of the present invention is to provide a pressure-sensitive adhesive composition containing an acrylic block copolymer which is free from bleeding and excellent in transparency, tack and thermal stability.

  As a result of intensive studies to achieve the above object, the present inventors have obtained a pressure-sensitive adhesive containing a specific acrylic triblock copolymer and a specific acrylic diblock copolymer at a specific blending ratio. It was found that a pressure-sensitive adhesive composition containing an acrylic block copolymer having no bleed and excellent in transparency, tack and thermal stability can be obtained by using the composition.

According to the invention, the object is
[1] (i) having two polymer blocks (A1) and (A2) composed of methacrylate units and one polymer block (B) composed of acrylate units;
Acrylic acid ester units constituting the polymer block (B) are represented by the general formula CH ₂ = CH-COOR ¹ (1) (wherein R ¹ represents an organic group having 4 to 6 carbon atoms). An acid ester (1) unit and a general formula CH ₂ ═CH—COOR ² (2) (wherein R ² represents an organic group having 7 to 12 carbon atoms) and an acrylic ester (2) unit,
(A1)-(B)-(A2) having a block structure, having a weight average molecular weight (Mw) of 40,000 to 200,000, and a polymer block (A1 in the acrylic triblock copolymer (I)) ) And (A2), the acrylic triblock copolymer (I) having a total content of 35% by mass or less, and (ii) one polymer block (C) composed of methacrylic acid ester units and acrylic One polymer block (D) consisting of acid ester units,
(C)-(D) having a block structure, having a weight average molecular weight (Mw) of 10,000 to 120,000, and the content of the polymer block (C) in the acrylic diblock copolymer (II) An adhesive composition containing 1 to 500 parts by mass of an acrylic diblock copolymer (II) having a content of 25% by mass or less,
Is achieved by providing

  According to the present invention, there can be obtained an adhesive composition containing an acrylic block copolymer having no bleeding and excellent in transparency, tack and thermal stability.

  Hereinafter, the present invention will be described in detail. In the present specification, “(meth) acrylic acid ester” is a general term for “methacrylic acid ester” and “acrylic acid ester”, and “(meth) acrylic” means “methacrylic” and “acrylic”. It is a generic name.

(Acrylic triblock copolymer (I))
The acrylic triblock copolymer (I) contained in the adhesive composition of the present invention is composed of two polymer blocks (A1) and (A2) composed of methacrylic ester units and 1 composed of acrylate units. The acrylate unit constituting the polymer block (B) has a general formula CH ₂ = CH-COOR ¹ (1) (wherein R ¹ has 4 carbon atoms). An acrylate ester unit (1) represented by ˜6 and a general formula CH ₂ ═CH—COOR ² (2) (wherein R ² represents an organic group having 7 to 12 carbon atoms). Acrylic triblock consisting of the acrylic ester (2) unit shown, having a (A1)-(B)-(A2) block structure, and having a weight average molecular weight (Mw) of 40,000 to 200,000 Copolymer (I) The total content of kicking polymer block (A1) and (A2) is not more than 35 wt%.

(Polymer blocks (A1) and (A2))
The acrylic triblock copolymer (I) has a polymer block consisting of two methacrylic acid ester units of polymer blocks (A1) and (A2) consisting of methacrylic acid ester units.

  Examples of the methacrylic acid ester constituting the structural units of the polymer blocks (A1) and (A2) include, for example, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, and methacrylic acid. Isobutyl, sec-butyl methacrylate, tert-butyl methacrylate, n-hexyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, lauryl methacrylate, tridecyl methacrylate, stearyl methacrylate, methacrylic acid Methacrylic acid ester having no functional group such as isobornyl, phenyl methacrylate, benzyl methacrylate; methoxyethyl methacrylate, ethoxyethyl methacrylate, diethylamino methacrylate Ethyl, 2-hydroxyethyl methacrylate, 2-aminoethyl methacrylate, glycidyl methacrylate, and methacrylic acid esters having a functional group such as tetrahydrofurfuryl methacrylate.

  Among these, from the viewpoint of improving the heat resistance and durability of the obtained polymer, a methacrylate having no functional group is preferred, methyl methacrylate, ethyl methacrylate, tert-butyl methacrylate, cyclohexyl methacrylate, More preferred are isobornyl methacrylate and phenyl methacrylate, and methyl methacrylate is more preferred in that the phase separation between the polymer blocks (A1) and (A2) and the polymer block (B) becomes clearer and the cohesive force becomes higher. . The polymer blocks (A1) and (A2) may be composed of one kind of these methacrylic acid esters or may be composed of two or more kinds. The acrylic triblock copolymer (I) has two polymer blocks (A1) and (A2) as polymer blocks composed of methacrylic acid ester units. These polymer blocks (A1) and The methacrylic acid esters constituting (A2) may be the same or different. Further, the ratio of the methacrylic acid ester units contained in the polymer blocks (A1) and (A2) is preferably 60% by mass or more in each polymer block of the polymer blocks (A1) and (A2). More preferably, it is 90 mass% or more, and more preferably 95 mass% or more. Moreover, 100 mass% may be sufficient as the ratio of the methacrylic acid ester unit of a polymer block (A1) and (A2).

  In addition, the stereoregularity of the methacrylic acid ester unit contained in each polymer block (A1) and (A2) composed of the methacrylic acid ester unit may be the same as or different from each other.

  In the acrylic triblock copolymer (I), the total content of the polymer blocks (A1) and (A2) is 35% by mass or less, preferably 30% by mass or less, and preferably 25% by mass or less. Is more preferable, and it is further more preferable that it is 20 mass% or less. The total content of the polymer blocks (A1) and (A2) is preferably 4% by mass or more, and more preferably 8% by mass or more. When the total content of the polymer blocks (A1) and (A2) is within the above range, when the acrylic triblock copolymer (I) is used in an adhesive composition, excellent cohesive force is obtained. Expresses and improves tack and adhesion. Moreover, this adhesive composition tends to be more excellent in heat-resistant adhesiveness and holding power. The contents of the polymer blocks (A1) and (A2) contained in the acrylic triblock copolymer (I) may be the same or different.

  The glass transition temperature (Tg) of each of the polymer blocks (A1) and (A2) is preferably 60 to 140 ° C, more preferably 70 to 130 ° C, and further preferably 80 to 130 ° C. preferable. When the glass transition temperature is within this range, the polymer blocks (A1) and (A2) act as physical pseudo-crosslinking points at the normal use temperature of the adhesive, and express cohesive force. When used in an adhesive composition, it excels in adhesive strength, durability, heat resistance and the like. In addition, the glass transition temperature in this specification is the extrapolation start temperature of the curve obtained by DSC measurement.

  Tg of each of the polymer blocks (A1) and (A2) may be the same or different. Even when the Tg of each of the polymer blocks (A1) and (A2) is different, it is a preferred embodiment that the Tg of both polymer blocks is in the above range.

(Polymer block (B))
The acrylic triblock copolymer (I) has one polymer block (B) composed of acrylic ester units, and the acrylic ester units are represented by the general formula CH ₂ = CH-COOR ¹ (1) ( In the formula, R1 represents an acrylic ester (1) unit represented by an organic group having 4 to 6 carbon atoms) and a general formula CH ₂ = CH-COOR ² (2) (wherein R ² has 7 to 7 carbon atoms) (Representing 12 organic groups)).

  Examples of the acrylate ester (1) include n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, tert-butyl acrylate, amyl acrylate, isoamyl acrylate, n-hexyl acrylate, and cyclohexyl acrylate. And acrylic acid ester having no functional group such as phenyl acrylate; acrylic acid ester having functional group such as ethoxyethyl acrylate, diethylaminoethyl acrylate, tetrahydrofurfuryl acrylate, and the like.

  Among these, from the viewpoint of improving the transparency, flexibility and heat resistance of the resulting adhesive composition, acrylic esters having no functional group are preferable, and n-butyl acrylate and n-hexyl acrylate are preferred. Is more preferable, and n-butyl acrylate is more preferable. These acrylic acid esters (1) may be used alone or in combination of two or more.

  Examples of the acrylate ester (2) include 2-ethylhexyl acrylate, n-octyl acrylate, isooctyl acrylate, decyl acrylate, isobornyl acrylate, lauryl acrylate, benzyl acrylate, phenoxyethyl acrylate, and the like. It is done.

  Among these, from the viewpoint of improving the transparency, flexibility, cold resistance, and low temperature characteristics of the resulting adhesive composition, 2-ethylhexyl acrylate, n-octyl acrylate, isooctyl acrylate, lauryl acrylate, Acrylic esters such as phenoxyethyl acrylate are preferred. In addition, the obtained adhesive composition is excellent in tack and adhesive strength at low temperatures (10 to -40 ° C), and exhibits stable adhesive force under a wide range of peeling speed conditions, so that 2-ethylhexyl acrylate, N-octyl acrylate and isooctyl acrylate are more preferable. Furthermore, in the case of 2-ethylhexyl acrylate, the phase separation between the polymer blocks (A1) and (A2) and the polymer block (B) becomes clearer. This is particularly preferable in terms of expressing a high cohesive force. These acrylic acid esters (2) may be used alone or in combination of two or more.

  The mass ratio (1) / (2) of the acrylic ester (1) and acrylic ester (2) in the polymer block (B) is preferably 5/95 to 95/5. When the mass ratio is within the above range, both adhesive force and tack can be achieved. Furthermore, the mass ratio (1) / (2) of the acrylic acid ester is more preferably 25/75 to 75/25, and further preferably 40/60 to 60/40. In addition, mass ratio of acrylic ester (1) and acrylic ester (2) is calculated | required by the method as described in the below-mentioned Example.

As a combination of acrylic acid ester used for the polymer block (B), for example, (1) / (2) is n-butyl acrylate / 2-ethylhexyl acrylate, n-butyl acrylate / octyl acrylate, N-hexyl acrylate / 2-ethylhexyl acrylate, n-butyl acrylate / lauryl acrylate, n-butyl acrylate / benzyl acrylate, n-butyl acrylate / [2-ethylhexyl acrylate / lauryl acrylate], etc. Is mentioned. At this time, the acrylic ester (1) and the acrylic ester (2) to be used have a solubility parameter difference of 1.0 to 2.5 (MPa) ¹ between the acrylic ester (1) and the acrylic ester (2). More preferably ^{/ 2} . The solubility parameter referred to in the present invention is “POLYMER HANDBOOK Forth Edition”, VII pages 675-714 (Wiley Interscience, published in 1999) and “Polymer Engineering and Science”, 1974, pages 147-147. It can be calculated by the method described on page 154.

  The polymer block (B) may be composed of a random copolymer of the acrylate ester (1) and the acrylate ester (2) constituting the polymer block (B), or may be composed of a block copolymer. However, a taper block copolymer may be used, but a random copolymer is particularly preferable.

  The total proportion of the acrylate (1) unit and the acrylate (2) unit contained in the polymer block (B) is preferably 60% by mass or more, more preferably 80% by mass or more, and 90% by mass or more. More preferably, 95 mass% or more is still more preferable. Moreover, 100 mass% may be sufficient as the total ratio of the acrylic ester (1) unit and acrylic ester (2) unit of a polymer block (B).

  In the acrylic triblock copolymer (I), the content of the polymer block (B) is usually 65% by mass or more, preferably 70% by mass or more, and more preferably 75% by mass or more. Preferably, it is 80 mass% or more. Moreover, it is preferable that content of a polymer block (B) is 96 mass% or less, and it is more preferable that it is 92 mass% or less. When the content of the polymer block (B) is within the above range, when the acrylic triblock copolymer (I) is used for the adhesive composition, it exhibits excellent cohesive force, Adhesive strength is further improved.

  The glass transition temperature (Tg) of the polymer block (B) is preferably −100 to 30 ° C., more preferably −80 to 10 ° C., and further preferably −70 to 0 ° C. When the glass transition temperature is within this range, it can have excellent tack and adhesive strength when used in an adhesive composition.

  The polymer blocks (A1) and (A2) and the polymer block (B) may contain monomer components of each other as long as the effects of the present invention are not impaired. For example, you may have a tapered structure in the boundary of a polymer block (A1) or (A2) and a polymer block (B). Moreover, the polymer block (A1) or (A2) and the polymer block (B) may not contain each other's monomer components.

  Moreover, the said polymer block (A1) and (A2) and a polymer block (B) may contain another monomer as needed. Examples of such other monomers include vinyl monomers having a carboxyl group such as (meth) acrylic acid, crotonic acid, maleic acid, maleic anhydride, and fumaric acid; (meth) acrylamide, (meth) acrylonitrile, Vinyl monomers having functional groups such as vinyl acetate, vinyl chloride, vinylidene chloride; aromatic vinyl monomers such as styrene, α-methylstyrene, p-methylstyrene, m-methylstyrene; butadiene, isoprene, etc. Conjugated diene monomers; olefin monomers such as ethylene, propylene, isobutene and octene; and lactone monomers such as ε-caprolactone and valerolactone. When each polymer block contains these other monomers, the content thereof is preferably 20% by mass or less, more preferably 10% by mass with respect to the total mass of monomers constituting each polymer block. % Or less, more preferably 5% by mass or less.

  The acrylic triblock copolymer (I) has a (A1)-(B)-(A2) block structure in which the polymer block (A1), the polymer block (B), and the polymer block (A2) are bonded in this order. Have When the acrylic triblock copolymer (I) has this structure, an adhesive composition excellent in adhesive strength, holding power and cohesive strength can be obtained.

  The weight average molecular weight (Mw) of the acrylic triblock copolymer (I) is 40,000 to 200,000. From the point of cohesive force and handling at the time of manufacture, it is preferably 50,000 to 180,000, more preferably 55,000 to 160,000, and 60,000 to 140,000. Is more preferable. If the Mw of the acrylic triblock copolymer (I) is less than 40,000, the cohesive force may be inferior. Moreover, when Mw exceeds 200,000, there exists a possibility that the handleability at the time of manufacture may be inferior.

  The molecular weight distribution (Mw / Mn) of the acrylic triblock copolymer (I) is preferably 1.0 to 1.5, and more preferably 1.0 to 1.4. In addition, the weight average molecular weight (Mw) and the number average molecular weight (Mn) in this specification are the weight average molecular weight and number average molecular weight in terms of standard polystyrene determined by gel permeation chromatography (GPC) measurement.

(Acrylic diblock copolymer (II))
The acrylic acrylic diblock copolymer (II) contained in the adhesive composition of the present invention is composed of one polymer block (C) composed of methacrylate units and one heavy polymer composed of acrylic ester units. A diblock copolymer (II), a (C)-(D) block structure, a weight average molecular weight (Mw) of 10,000 to 120,000, and an acrylic diblock copolymer (II) The content of the polymer block (C) in is 25% by mass or less.

(Polymer block (C))
The acrylic diblock copolymer (II) has one polymer block (C) composed of methacrylic acid ester units.

  Specific examples of the methacrylic ester serving as the structural unit of the polymer block (C) include a methacrylic ester serving as the structural unit of the polymer blocks (A1) and (A2) of the acrylic triblock copolymer (I) and It is the same.

  Among these, from the viewpoint of improving the heat resistance and durability of the obtained polymer, a methacrylate having no functional group is preferred, methyl methacrylate, ethyl methacrylate, tert-butyl methacrylate, cyclohexyl methacrylate, Isobornyl methacrylate and phenyl methacrylate are more preferable, and methyl methacrylate is more preferable from the viewpoint that the phase separation between the polymer block (C) and the polymer block (D) becomes clearer and the cohesive force becomes high. The polymer block (C) may be composed of one kind of these methacrylic acid esters or may be composed of two or more kinds. The proportion of the methacrylic acid ester unit contained in the polymer block (C) is preferably 60% by mass or more, more preferably 80% by mass or more, further preferably 90% by mass or more, and still more preferably 95% by mass or more. Moreover, 100 mass% may be sufficient as the ratio of the methacrylic acid ester unit of a polymer block (C).

  In the acrylic diblock copolymer (II), the content of the polymer block (C) is 25% by mass or less, preferably 20% by mass or less, and more preferably 10% by mass or less. Moreover, it is preferable that content of a polymer block (C) is 2 mass% or more, and it is preferable that it is 4 mass% or more. When the content of the polymer block (C) is within the above range, when the acrylic diblock copolymer (II) is contained in the adhesive composition, the cohesive force is not impaired, and tack and There exists a tendency for workability to improve more.

  The glass transition temperature (Tg) of the polymer block (C) is preferably 60 to 140 ° C, more preferably 70 to 130 ° C, and further preferably 80 to 130 ° C. When the glass transition temperature is in this range, the polymer block (C) acts as a physical pseudo-crosslinking point at the normal use temperature of the adhesive, and expresses cohesive force. When contained in the composition, it is excellent in adhesive strength, durability, heat resistance and the like.

(Polymer block (D))
The acrylic diblock copolymer (II) has one polymer block (D) composed of an acrylate unit.

  Examples of the acrylic ester serving as the structural unit of the polymer block (D) include methyl acrylate, ethyl acrylate, isopropyl acrylate, n-propyl acrylate, n-butyl acrylate, isobutyl acrylate, and acrylic acid. sec-butyl, tert-butyl acrylate, amyl acrylate, isoamyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, isooctyl acrylate, decyl acrylate, isobornyl acrylate, acrylic acid Acrylic esters without functional groups such as lauryl, octadecyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate; methoxyethyl acrylate, ethoxyethyl acrylate, 2-hydroacrylate Shiechiru, 2-aminoethyl acrylate, glycidyl acrylate, tetrahydrofurfuryl acrylate, diethylaminoethyl acrylate, such as phenoxyethyl acrylate, acrylic acid ester having a functional group.

Among these, from the viewpoint of transparency and flexibility when the adhesive composition is used, the general formula (3) CH ₂ = CH-COOR ³ (wherein R ³ represents an organic group having 1 to 10 carbon atoms). Acrylic acid ester (3) is more preferable, and the phase separation between the polymer block (C) and the polymer block (D) becomes clear, and the adhesive composition exhibits high cohesive force. Methyl acrylate, ethyl acrylate, isopropyl acrylate, n-propyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, tert-butyl acrylate, amyl acrylate, isoamyl acrylate, n-acrylate -Hexyl, 2-ethylhexyl acrylate, n-octyl acrylate, isooctyl acrylate, decyl acrylate, isobornyl acrylate, a Cyclohexyl acrylic acid, phenyl acrylate, such as benzyl acrylate, acrylic acid ester is more preferably without a functional group. Furthermore, from the point that the adhesive composition has an appropriate adhesive strength and tack at room temperature and exhibits a stable adhesive strength under a wide temperature range and a wide peeling rate condition, methyl acrylate, acrylic acid n At least one selected from -butyl, 2-ethylhexyl acrylate, n-octyl acrylate, and isooctyl acrylate is more preferable, and n-butyl acrylate and 2-ethylhexyl acrylate are particularly preferable.

  The polymer block (D) may be composed of one kind of these acrylate esters or may be composed of two or more kinds. When comprised from 2 or more types, the thing which consists of n-butyl acrylate and 2-ethylhexyl acrylate from a flexible viewpoint at the time of setting it as an adhesive composition and cold resistance is preferable. The proportion of the acrylate unit contained in the polymer block (D) is preferably 60% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, and still more preferably 95% by mass or more. Moreover, 100 mass% may be sufficient as the ratio of the acrylic ester unit of a polymer block (D).

  In the acrylic diblock copolymer (II), the content of the polymer block (D) is usually 75% by mass or more, preferably 80% by mass or more, and more preferably 90% by mass or more. preferable. Moreover, it is preferable that content of a polymer block (D) is 98 mass% or less, and it is more preferable that it is 96 mass% or less. When the content of the polymer block (D) is within the above range, when the acrylic diblock copolymer (II) is contained in the adhesive composition, the cohesive force is not impaired, and tack and Workability is further improved.

  The glass transition temperature (Tg) of the polymer block (D) is preferably −100 to 30 ° C., more preferably −80 to 10 ° C., and further preferably −70 to 0 ° C. When the glass transition temperature is within this range, it can have excellent tack and adhesive strength when used in an adhesive composition.

  The polymer block (C) and the polymer block (D) may contain monomer components of each other as long as the effects of the present invention are not impaired. For example, you may have a tapered structure in the boundary of a polymer block (C) and a polymer block (D). Moreover, the polymer block (C) and the polymer block (D) may not contain each other's monomer components.

  Moreover, the said polymer block (C) and polymer block (D) may contain another monomer unit as needed. Specific examples of such other monomers are contained in the polymer block polymer blocks (A1) and (A2) and the polymer block (B) of the acrylic triblock copolymer (I) as necessary. It is the same as that of the other monomer illustrated as what is used for another monomer unit. When each polymer block contains these other monomers, the content thereof is preferably 20% by mass or less, more preferably 10% by mass with respect to the total mass of monomers constituting each polymer block. % Or less, more preferably 5% by mass or less.

  The acrylic diblock copolymer (II) has a (C)-(D) block structure in which the polymer block (C) and the polymer block (D) are bonded in this order. When the acrylic diblock copolymer (II) having such a structure is contained in the adhesive composition, tack and workability tend to be further improved.

  The weight average molecular weight (Mw) of the acrylic diblock copolymer (II) is 10,000 to 120,000. From the point of cohesive force and handling at the time of manufacture, it is preferably 20,000 to 110,000, more preferably 25,000 to 100,000, and 30,000 to 90,000. Is more preferable. If the Mw of the acrylic diblock copolymer (II) is less than 10,000, the cohesive force may be inferior. Moreover, when Mw exceeds 120,000, there exists a possibility that the handleability at the time of manufacture may be inferior.

The molecular weight distribution (Mw / Mn) of the acrylic diblock copolymer (II) is preferably 1.0 to 1.5, and more preferably 1.0 to 1.4.
In the adhesive composition of the present invention, the content of the acrylic diblock copolymer (II) is 1 to 500 parts by mass with respect to 100 parts by mass of the acrylic triblock copolymer (I). By including the acrylic triblock copolymer (I) and the acrylic diblock copolymer (II) in such a quantitative ratio in the adhesive composition, a tackifying resin is added to the adhesive. Even when a plasticizer is not contained, an adhesive composition excellent in transparency, bleed resistance, tack and thermal stability can be obtained. If the content of the acrylic diblock copolymer (II) is less than 1 part by mass relative to 100 parts by mass of the acrylic triblock copolymer (I), the tack and workability improvement effects may not be obtained. When the content of the acrylic diblock copolymer (II) exceeds 500 parts by mass, the cohesive force of the resulting adhesive composition may be impaired. In addition, in the adhesive composition of this invention, it is a preferable aspect that a tackifying resin and a plasticizer are not contained as a component from the viewpoint of bleeding resistance and thermal stability. From the viewpoint of cohesive force, workability, adhesive force, and tack balance, the content of the acrylic diblock copolymer (II) is 10 to 400 with respect to 100 parts by mass of the acrylic triblock copolymer (I). It is preferable that it is a mass part, and it is more preferable that it is 20-300 mass parts.

  The production method of the acrylic triblock copolymer (I) and the acrylic diblock copolymer (II) used in the present invention is particularly limited as long as a polymer satisfying the conditions of the present invention concerning the chemical structure is obtained. The method according to a known method can be adopted without being done. In general, as a method of obtaining a block copolymer having a narrow molecular weight distribution, a method of living polymerizing monomers as constituent units is used. Examples of such living polymerization methods include a method of living polymerization using an organic rare earth metal complex as a polymerization initiator (see JP 06-93060 A), and an alkali metal or alkaline earth using an organic alkali metal compound as a polymerization initiator. Living anionic polymerization in the presence of mineral salts such as salts of metal salts (see Japanese Patent Publication No. 05-507737), Living anionic polymerization using organic alkali metal compound as polymerization initiator in the presence of organoaluminum compound (Refer to JP-A-11-335432), atom transfer radical polymerization method (ATRP) (see Macromolecular Chemistry and Physics, 2000, 201, p. 1108 to 1114).

  Among the above production methods, the method of living anion polymerization using an organoalkali metal compound as a polymerization initiator in the presence of an organoaluminum compound makes the resulting block copolymer highly transparent, has little residual monomer and has an odor. In addition, when used as an adhesive composition, the generation of bubbles after bonding can be suppressed, which is preferable. Furthermore, the molecular structure of the methacrylic acid ester polymer block is highly syndiotactic, which has the effect of increasing the heat resistance of the adhesive composition, and is capable of living polymerization under relatively mild temperature conditions. In production, it is also preferable in that the environmental load (mainly the electric power applied to the refrigerator for controlling the polymerization temperature) is small.

As the organoaluminum compound, for example, the following general formula (4)
AlR ⁴ R ⁵ R ⁶ (4)
(In the formula (4), R ⁴ , R ⁵ and R ⁶ each independently have an alkyl group which may have a substituent, an cycloalkyl group which may have a substituent, or a substituent. An aryl group which may have a substituent, an aralkyl group which may have a substituent, an alkoxy group which may have a substituent, an aryloxy group which may have a substituent or an N, N-disubstituted amino group. Or R ⁴ is any of the groups described above, and R ⁵ and R ⁶ together form an aryleneoxy group which may have a substituent. An aluminum compound is mentioned.

  As the organoaluminum compound represented by the general formula (4), isobutyl bis (2,6-di-tert-butyl-4-methylphenoxy) is used from the viewpoint of high living property of polymerization and easy handling. Preferred examples include aluminum, isobutylbis (2,6-di-tert-butylphenoxy) aluminum, isobutyl [2,2′-methylenebis (4-methyl-6-tert-butylphenoxy)] aluminum, and the like.

  Examples of the organic alkali metal compounds include alkyl lithium and alkyl dilithium such as n-butyl lithium, sec-butyl lithium, isobutyl lithium, tert-butyl lithium, n-pentyl lithium, and tetramethylene dilithium; phenyl lithium, p -Aryllithium and aryldilithium such as tolyllithium and lithium naphthalene; aralkyllithium and aralkyldilithium such as dilithium produced by the reaction of benzyllithium, diphenylmethyllithium, diisopropenylbenzene and butyllithium; lithium such as lithium dimethylamide Amides; lithium alkoxides such as methoxy lithium and ethoxy lithium, and the like. These may be used alone or in combination of two or more. Of these, alkyl lithium is preferable because of high polymerization initiation efficiency, among which tert-butyl lithium and sec-butyl lithium are more preferable, and sec-butyl lithium is more preferable.

  The living anion polymerization is usually performed in the presence of a solvent inert to the polymerization reaction. Examples of the solvent include aromatic hydrocarbons such as benzene, toluene, and xylene; halogenated hydrocarbons such as chloroform, methylene chloride, and carbon tetrachloride; ethers such as tetrahydrofuran and diethyl ether, and toluene is preferably used. It is done.

  The block copolymer includes, for example, a step of forming a desired polymer block (polymer block (A1), polymer block (B), etc.) at a desired living polymer terminal obtained by polymerizing monomers. After repeating the desired number of times, it can be produced by stopping the polymerization reaction. Specifically, for example, in the presence of an organoaluminum compound, a first step of polymerizing a monomer that forms the first polymer block with a polymerization initiator composed of an organic alkali metal compound, the second polymer block The weight obtained through a plurality of polymerization steps including a second step for polymerizing the monomer to be formed and a third step for polymerizing the monomer for forming the third polymer block as necessary. The acrylic triblock copolymer (I) and the acrylic diblock copolymer (II) can be produced by reacting the active terminal of the coal with alcohol or the like to stop the polymerization reaction. According to the above method, a triblock copolymer comprising polymer block (A1) -polymer block (B) -polymer block (A2), polymer block (C) -polymer block (D). The diblock copolymer which consists of can be manufactured.

  The polymerization temperature is 0 to 100 ° C. when forming the polymer blocks (A1), (A2) and (C), and −50 to 50 ° C. when forming the polymer blocks (B) and (D). preferable. When the polymerization temperature is lower than the above range, the progress of the reaction is slow, and it takes a long time to complete the reaction. On the other hand, when the polymerization temperature is higher than the above range, the deactivation of the living polymer ends increases, the molecular weight distribution becomes wide, and the desired block copolymer cannot be obtained. Each polymer block can be polymerized in the range of 1 second to 20 hours.

  The adhesive composition of the present invention is a polymer that does not impair the effects of the present invention; other polymers; softeners, heat stabilizers, light stabilizers, antistatic agents, flame retardants, foaming agents, colorants, Additives such as a staining agent, a refractive index adjusting agent, a filler, a curing agent, and an anti-sticking agent may be contained. These other polymers and additives may be included singly or in combination of two or more. In addition, it is a preferable aspect that the tackifying resin and the plasticizer are not included as an additive of the adhesive composition of the present invention.

  Examples of other polymers include acrylic resins such as polymethyl methacrylate and (meth) acrylic acid ester copolymers; polyethylene, ethylene-vinyl acetate copolymer, polypropylene, polybutene-1, and poly-4-methyl. Olefin resins such as pentene-1 and polynorbornene; ethylene ionomers; polystyrene, styrene-maleic anhydride copolymer, high impact polystyrene, AS resin, ABS resin, AES resin, AAS resin, ACS resin, MBS resin, etc. Styrene resin; Styrene-methyl methacrylate copolymer; Polyester resin such as polyethylene terephthalate, polybutylene terephthalate and polylactic acid; Polyamide such as nylon 6, nylon 66 and polyamide elastomer; Polycarbonate; Polyvinyl chloride; Polyvinyl alcohol; Ethylene-vinyl alcohol copolymer; Polyacetal; Polyvinylidene fluoride; Polyurethane; Modified polyphenylene ether; Polyphenylene sulfide; Silicone rubber modified resin; Acrylic rubber; Silicone rubber; Sstyrene such as SEPS, SEBS, SIS Thermoplastic elastomers; olefin rubbers such as IR, EPR, and EPDM. Among these, from the viewpoint of compatibility with the acrylic triblock copolymer (I) contained in the adhesive composition, acrylic resin, ethylene-vinyl acetate copolymer, AS resin, polylactic acid, Polyvinylidene fluoride and styrenic thermoplastic elastomer are preferred, and (meth) acrylic acid ester copolymers are more preferred.

  Examples of the filler include inorganic fibers such as glass fibers and carbon fibers, and organic fibers; inorganic fillers such as calcium carbonate, talc, titanium oxide, silica, clay, barium sulfate, and magnesium carbonate; and carbon black. . When these fillers are contained, durability, heat resistance, and weather resistance are imparted to the resulting adhesive composition.

  When a hardener is included in the adhesive composition of the present invention, it can be suitably used as a curable adhesive. Examples of the curing agent include photocuring agents such as UV curing agents, thermosetting agents, and the like, and examples include benzoins, benzoin ethers, benzophenones, anthraquinones, benzyls, acetophenones, and diacetyls. . Specifically, benzoin, α-methylol benzoin, α-t-butyl benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin-n-propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, α-methylol benzoin methyl ether, α -Methoxybenzoin methyl ether, benzoin phenyl ether, benzophenone, 9,10-anthraquinone, 2-ethyl-9,10-anthraquinone, benzyl, 2,2-dimethoxy-1,2-diphenylethane-1-one (2,2 -Dimethoxy-2-phenylacetophenone), diacetyl and the like. A hardening | curing agent may be contained individually by 1 type, and 2 or more types may be contained.

  From the viewpoint of enhancing the effect of the curing agent, for example, acrylic acid, methacrylic acid, α-cyanoacrylic acid, α-halogenated acrylic acid, crotonic acid, cinnamic acid, sorbic acid, maleic acid, itaconic acid, and acrylic acid ester , Methacrylic acid ester, crotonic acid ester, maleic acid ester, etc .; acrylamide; methacrylamide; acrylamide derivatives such as N-methylolacrylamide, N-hydroxyethylacrylamide, N, N- (dihydroxyethyl) acrylamide; N-methylolmethacrylic Methamide derivatives such as amide, N-hydroxyethyl methacrylamide, N, N- (dihydroxyethyl) methacrylamide; vinyl esters; vinyl ethers; mono-N-vinyl derivatives; monomers such as styrene derivatives; An oligomer containing the monomer as a constituent component may be further included in the adhesive composition of the present invention. From the viewpoint of enhancing durability, esters such as acrylic acid esters, methacrylic acid esters, crotonic acid esters, and maleic acid esters; vinyl ethers; styrene derivatives; and oligomers containing the aforementioned monomers as constituents are preferred. In addition to these monomers, a cross-linking agent composed of a bifunctional or higher functional monomer or oligomer may be further contained.

  When an anti-sticking agent is included in the adhesive composition of the present invention, improvement in handleability can be expected. Examples of the anti-sticking agent include fatty acids such as stearic acid and palmitic acid; fatty acid metal salts such as calcium stearate, zinc stearate, magnesium stearate, potassium palmitate and sodium palmitate; polyethylene wax, polypropylene wax, montanic acid Waxes such as low molecular weight wax; low molecular weight polyolefin such as low molecular weight polyethylene and low molecular weight polypropylene; acrylic resin powder; polyorganosiloxane such as dimethylpolysiloxane; octadecylamine, alkyl phosphate, fatty acid ester, ethylenebisstearylamide, etc. Examples thereof include amide resin powder, fluororesin powder such as ethylene tetrafluoride resin, molybdenum disulfide powder, silicone resin powder, silicone rubber powder, silica and the like.

  The method for producing the adhesive composition of the present invention is not particularly limited. For example, each component is usually 100 by using a known mixing or kneading apparatus such as a kneader ruder, an extruder, a mixing roll, or a Banbury mixer. It can manufacture by mixing at the temperature in the range of -250 degreeC. Moreover, after dissolving each component in an organic solvent and mixing, you may manufacture by distilling off this organic solvent. The obtained adhesive composition can be used by heating and melting, or it may be dissolved in a solvent and used as a solution-type adhesive. Examples of the solvent include toluene, ethyl acetate, ethylbenzene, methylene chloride, chloroform, tetrahydrofuran, methyl ethyl ketone, dimethyl sulfoxide, toluene-ethanol mixed solvent, and the like. Of these, toluene, ethylbenzene, ethyl acetate, and methyl ethyl ketone are preferable.

  In addition, when using the adhesive composition of this invention heat-melting, it is preferable that a melt viscosity is low from a viewpoint of workability and handleability. On the other hand, it is preferable that the melt viscosity is high from the viewpoint of achieving both adhesive strength and high holding power (creep resistance) of the adhesive composition.

  The pressure-sensitive adhesive composition of the present invention is a pressure-sensitive adhesive in the form of a pressure-sensitive adhesive layer comprising the pressure-sensitive adhesive composition or a laminate (for example, a laminated film or a sheet) including the pressure-sensitive adhesive layer. It is suitably used for adhesive products.

  In order to form the above-mentioned adhesive layer, when the adhesive composition of the present invention is heated and melted, for example, a hot melt coating method, a T-die method, an inflation method, a calendar molding method, a lamination method, etc. It can be formed into a sheet shape or a film shape. For example, the adhesive layer can be formed on a film or sheet of a heat-resistant material such as polyethylene terephthalate by using a method of melt-coating the heat-adhesive adhesive composition using a hot melt coater. When the melt viscosity of the adhesive composition of the present invention is high, for example, when the melt viscosity at 180 ° C. exceeds 20,000 mPa · s, in order to heat and melt at a higher temperature, A hot melt coating method in which the heated melt is applied on the support in a non-contact manner is preferred from the viewpoints of thickness control of the adhesive layer, homogeneity, and heat resistance necessary for the support. Further, when the adhesive composition of the present invention is used by dissolving in a solvent, for example, a heat resistant material such as polyethylene terephthalate or a flat plate or roll such as a steel belt is used as a support, and a bar coater, Using a roll coater, die coater, comma coater, etc., apply a solution prepared by dissolving a composition containing acrylic triblock copolymer (I) and acrylic diblock copolymer (II) in a solvent, and then dry. The adhesive layer can be formed by using a method for removing the solvent (solution casting method).

  The method for removing the solvent by drying is not particularly limited, and a conventionally known method can be used, but it is preferable to perform drying in a plurality of stages. When drying is performed in a plurality of stages, the first stage of drying is performed at a relatively low temperature in order to suppress foaming due to rapid volatilization of the solvent. In order to remove the solvent, a method of drying at a high temperature is more preferable.

  The concentration of the composition containing the acrylic triblock copolymer (I) and the acrylic diblock copolymer (II) in the above solution takes into account the solubility of the composition in a solvent, the viscosity of the resulting solution, and the like. The lower limit is preferably 5% by mass and the upper limit is preferably 70% by mass.

  The laminate is obtained by laminating an adhesive layer composed of the adhesive composition of the present invention and various base materials such as paper, cellophane, plastic material, cloth, wood, and metal. A base material layer made of a transparent material is suitable because the adhesive composition of the present invention is excellent in transparency and weather resistance, so that a transparent laminate can be obtained. As the base material layer made of a transparent material, polyethylene terephthalate, triacetyl cellulose, polyvinyl alcohol, cycloolefin resin, styrene-methyl methacrylate copolymer, polypropylene, polyethylene, polyvinyl chloride, ethylene-vinyl acetate copolymer , A copolymer of a polymer such as polycarbonate, polymethyl methacrylate, polyethylene or polypropylene and various monomers, a mixture of two or more of these polymers, and a base material layer made of glass, etc. It is not limited to these.

  As a structure of the said laminated body, the two-layer structure of the adhesive layer and base material layer which consist of an adhesive composition of this invention, for example, Two base material layers and the adhesive composition of this invention 3 layer constitution (base material layer / adhesive layer / base material layer) with two different adhesive layers (the base material layer and the adhesive composition of the present invention) a) and a four-layer configuration of an adhesive layer (b) and a base material layer (base material layer / adhesive layer (a) / adhesive layer (b) / base material layer), base material layer and book A four-layer structure (base layer / adhesive layer (a ) / Adhesive layer (c) / base material layer), 3 base material layers and 2 adhesive layers composed of the adhesive composition of the present invention (base material layer / adhesion) (Attachment layer / base material layer / adhesive layer / base material layer) and the like, but is not limited thereto.

  Although it does not restrict | limit especially as thickness ratio of the said laminated body, From the adhesive force of an adhesive product obtained, tack, durability, and handleability, the range of base material layer / adhesive layer = 1 / 1000-1000 / 1 Is preferable, and the range of 1/200 to 200/1 is more preferable.

  When the laminate is produced, the adhesive layer and the base material layer may be formed and then bonded together by a lamination method or the like, or the adhesive layer may be directly formed on the base material layer. Good. Moreover, a layered structure may be manufactured as a coextruded film or a coextruded sheet by forming a layer structure at one time by coextruding the adhesive layer and the base material layer.

  In the laminated body of this invention, in order to improve the adhesive force of a base material layer and an adhesive bond layer, you may give surface treatments, such as a corona discharge process and a plasma discharge process, to the surface of a base material layer previously. Moreover, you may form an anchor layer in the surface of at least one of the said adhesive layer and a base material layer using resin etc. which have adhesiveness.

  Examples of the resin used for the anchor layer include ethylene-vinyl acetate copolymers, ionomers, block copolymers (for example, styrene triblock copolymers such as SIS and SBS, and diblock copolymers). Examples thereof include an ethylene-acrylic acid copolymer and an ethylene-methacrylic acid copolymer. The anchor layer may be a single layer or two or more layers.

  In the case of forming the anchor layer, the method is not particularly limited. For example, a method of forming the anchor layer by applying a solution containing the resin to the base material layer, a composition containing the resin to be the anchor layer, and the like. And a method of forming an anchor layer on the surface of the base material layer by T-die or the like after heating and melting.

  When the anchor layer is formed, the anchor layer and the adhesive layer may be integrally laminated on the surface of the base material layer by co-extrusion of the resin used as the anchor layer and the adhesive composition of the present invention. Further, the anchor layer resin and the adhesive composition may be sequentially laminated on the surface of the base material layer. Furthermore, when the base material layer is a plastic material, the plastic material and anchor to be the base material layer The resin forming the layer and the adhesive composition may be coextruded at the same time.

  The adhesive which consists of an adhesive composition of this invention can be used for various uses. Moreover, the adhesive layer which consists of this adhesive composition can be used alone as an adhesive sheet, and the laminated body containing this adhesive layer can also be applied to various uses. For example, for surface protection, masking, binding, packaging, office, label, decoration / display, bonding, dicing tape, sealing, anticorrosion / waterproof, medical / hygiene, glass Adhesive for scattering prevention, electrical insulation, electronic device holding and fixing, semiconductor manufacturing, optical display film, adhesive adhesive optical film, electromagnetic wave shield, or electrical / electronic component sealing material , Adhesive tape, film or sheet. Specific examples are given below.

  Adhesive for surface protection, adhesive tape or film, etc. can be used for various materials such as metal, plastic, rubber, wood, specifically, paint surface, metal plastic processing or deep drawing, It can be used to protect the surface of automobile members and optical members. Examples of the automobile member include a painted outer plate, a wheel, a mirror, a window, a light, and a light cover. Examples of the optical member include various image display devices such as a liquid crystal display, an organic EL display, a plasma display, and a field emission display; a polarizing film, a polarizing plate, a retardation plate, a light guide plate, a diffusion plate, an optical disc constituting film such as a DVD;・ Precise fine coated face plate for optical applications.

  Masking adhesives, tapes, films, etc. include: masking when manufacturing printed circuit boards and flexible printed circuit boards; masking when plating and soldering on electronic equipment; manufacturing of vehicles such as automobiles, vehicles and architecture Examples include painting, printing, and masking when giving up on civil engineering work.

Examples of binding applications include wire harnesses, electric wires, cables, fibers, pipes, coils, windings, steel materials, ducts, plastic bags, foods, vegetables, and grooms.
Examples of packaging applications include heavy goods packaging, export packaging, cardboard box sealing, can seals, and the like.

The office use includes general office use, sealing, book repair, drafting, and memo.
Examples of label usage include price, product display, tag, POP, sticker, stripe, name plate, decoration, and advertisement.

  The labels include paper, processed paper (paper subjected to aluminum vapor deposition, aluminum lamination, varnishing, resin processing, etc.), paper such as synthetic paper; cellophane, plastic material, cloth, wood and metal The label which uses a film etc. as a base material is mentioned. Specific examples of the substrate include, for example, high-quality paper, art paper, cast paper, thermal paper, foil paper; polyethylene terephthalate film, polyvinyl chloride film, OPP film, polylactic acid film, synthetic paper, synthetic paper thermal, overlamination A film etc. are mentioned. Especially, the adhesive composition of this invention can be used suitably for the label using the base material which consists of a transparent material at the point which is excellent in transparency and a weather resistance. Moreover, since the adhesive composition of this invention has few discoloration with time, it can be used suitably for the thermal label which uses thermal paper or synthetic paper thermal as a base material.

  Examples of the adherend of the label include plastic products such as plastic bottles and foamed plastic cases; paper and cardboard products such as cardboard boxes; glass products such as glass bottles; metal products; and other inorganic material products such as ceramics. It is done.

  A label made of a laminate comprising an adhesive layer made of the adhesive composition of the present invention has little increase in adhesion during storage at a temperature slightly higher than room temperature (for example, 40 ° C.), and can be peeled off without any adhesive residue after use. it can. Moreover, it can be bonded to the adherend even at a low temperature (−40 to + 10 ° C.) and does not peel off even when stored at a low temperature (−40 to + 10 ° C.).

Examples of decoration / display applications include danger display stickers, line tapes, wiring markings, phosphorescent tapes, and reflective sheets.
Examples of adhesive film applications include polarizing films, polarizing plates, retardation films, viewing angle widening films, brightness enhancement films, antireflection films, antiglare films, color filters, light guide plates, diffusion films, prism sheets, and electromagnetic waves. Adhesive layer on at least part or all of one or both sides of shield film, near infrared absorption film, functional composite optical film, ITO bonding film, impact resistance imparting film, brightness enhancement film, visibility enhancement film, etc. The optical film etc. which formed are mentioned. Such an adhesive optical film includes a film in which an adhesive layer made of the adhesive composition of the present invention is formed on a protective film used for protecting the surface of the optical film. The adhesive type optical film is suitably used for various image display devices such as liquid crystal display devices, PDPs, organic EL display devices, electronic paper, game machines, and mobile terminals.

Examples of electrical insulation applications include protective coating or insulation of coils, interlayer insulation such as motors and transformers, and the like.
Electronic device holding and fixing applications include carrier tape, packaging, CRT fixing, splicing, rib reinforcement, and the like.

Examples of semiconductor manufacturing include protection of silicone wafers.
Examples of bonding applications include various bonding fields, automobiles, trains, electrical equipment, printing plate fixing, construction, nameplate fixing, general household use, rough surfaces, uneven surfaces, and adhesion to curved surfaces.

Sealing applications include heat insulation, vibration proofing, waterproofing, moisture proofing, soundproofing or dustproof sealing.
Examples of the anticorrosion / waterproofing include gas, water pipe corrosion prevention, large-diameter pipe corrosion prevention, and civil engineering building corrosion prevention.

For medical and hygiene applications, analgesic / anti-inflammatory agents (plasters, papps), ischemic heart disease treatments, female hormone supplements, bronchodilators, cancer pain relieving agents, smoking cessation aids, cold patches, antipruritic patches, Percutaneous absorption medicines such as keratin softeners; emergency bandages (with bactericides), surgical dressings / surgical tapes, bandages, hemostatic bonds, human excrement treatment attachment tapes (artificial anal fixation tapes), suture tapes, antibacterial tapes , Fixed taping, self-adhesive dressing, oral mucosa adhesive tape, sports tape, hair removal tape, etc .; cosmetic use such as face pack, moisturizing sheet, exfoliating pack; cooling sheet, thermal warmer, dustproof, Examples include waterproofing and pest capturing.
Examples of electronic / electrical component sealing materials include liquid crystal monitors and solar cells.

  EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to the following examples. In Synthesis Examples 1 to 5 shown below, monomers and other compounds were dried and purified by a conventional method and degassed with nitrogen. Moreover, transfer and supply of monomers and other compounds to the reaction system were performed in a nitrogen atmosphere.

Various physical properties of Examples and Comparative Examples were measured or evaluated by the following methods.
(1) Weight average molecular weight (Mw) and molecular weight distribution of acrylic triblock copolymers (I-1) to (I-3) and acrylic diblock copolymers (II-1) to (II-2) (Mw / Mn) was determined by GPC as a molecular weight in terms of standard polystyrene.
・ Equipment: GPC equipment “HLC-8020” manufactured by Tosoh Corporation
・ Separation column: “TSKgel GMHXL”, “G4000HXL” and “G5000HXL” manufactured by Tosoh Corporation are connected in series. ・ Eluent: Tetrahydrofuran ・ Eluent flow rate: 1.0 ml / min ・ Column temperature: 40 ° C.
・ Detection method: Differential refractive index (RI)

(2) The content of each polymer block in acrylic triblock copolymers (I-1) to (I-3) and acrylic diblock copolymers (II-1) to (II-2) is ¹ It was determined by 1 H-NMR measurement.
・ Apparatus: JEOL nuclear magnetic resonance apparatus “JNM-ECX400”
・ Solvent: Deuterated chloroform
^{In the 1} H-NMR spectrum, signals near 3.6 ppm and 4.0 ppm indicate that the ester group (—O—CH ₃ ) of the methyl methacrylate unit and the ester group (—O—C H ₂ ) of the acrylate unit, respectively. is attributed to -CH ₂ -CH ₂ -CH _3, or _{-O-C H 2 -CH (-CH} 2 -CH 3) -CH 2 -CH 2 -CH 2 -CH 3), co by the ratio of the integrated value The content of the polymerization component was determined.

(3) Polymer block (B) in acrylic triblock copolymers (I-1) to (I-3) and polymer block (D) in acrylic diblock copolymer (II-2) The ratio of the monomers constituting was determined by ¹ H-NMR measurement.
・ Apparatus: JEOL nuclear magnetic resonance apparatus “JNM-ECX400”
-Solvent: deuterated chloroform In the ¹ H-NMR spectrum of the mixed monomer used for the polymerization of the polymer block (B) or (D), signals near 4.1 ppm and 4.2 ppm are acrylic acid, respectively. n- butyl ester group _{(-O-C H 2 -CH 2} -CH 2 -CH 3) and 2-ethylhexyl acrylate ester groups _{(-O-C H 2 -CH (} -CH 2 -CH 3) - CH ₂ —CH ₂ —CH ₂ —CH ₃ ), and the content of each monomer in terms of the molar ratio is determined by the ratio of the integral values, and this is calculated based on the molecular weight of the monomer unit. It was converted into the mass ratio of the monomer constituting the polymer block (B) or (D).

(4) Bleed Bleeding or sticking of liquid material from the adhesive layer surface of the adhesive tape 24 hours after preparation of an adhesive tape having an adhesive layer with a thickness of 25 μm prepared by the method described later Evaluation was based on a decrease in tack due to bleeding of the applied resin. "None" if no liquid bleeding from the surface of the adhesive layer or tackiness due to bleeding of the tackifying resin is observed after 24 hours from the production of the adhesive tape, and "liquid" from the tape surface after 24 hours of production. If there was a decrease in tack due to bleeding or tackiness resin bleed, “Yes” was given.

(5) Tack It measured based on PSTC-16. That is, an adhesive tape having an adhesive layer with a thickness of 25 μm produced by a method described later is looped with a width of 25 mm and a length of 100 mm so that the adhesive surface comes to the outside, and “LT” manufactured by Chem Instruments is manufactured. The tack value (maximum value at the time of peeling) of a 25 mm wide PMMA plate attached in the direction crossing the loop was measured. A value of 5N or more at this time was designated as “A” (tack: high), indicating that it was suitable as a pressure-sensitive adhesive. On the other hand, those less than 5N were designated as “B” (tack: low) and unsuitable as pressure-sensitive adhesives.

(6) Thermal stability Thermal stability is performed by evaluating the color change of the appearance of an adhesive tape having a 25 μm thick adhesive layer produced by the method described below before and after heat treatment at 180 ° C. for 3 hours. It was. When no color change was observed on the appearance before and after the heat treatment, “A” (thermal stability: good), and “B” (thermal stability: bad) when the color change could be confirmed.

<< Synthesis Examples 1-5 >>
<< Synthesis Example 1 >> [Synthesis of Acrylic Triblock Copolymer (I-1)]
(1) A three-way cock was attached to a 2 L three-necked flask and the inside was replaced with nitrogen. Then, while stirring at room temperature, 1035 g of toluene and 31.9 g of 1,2-dimethoxyethane were added, followed by isobutylbis (2, 6-di-t-butyl-4-methylphenoxy) 41.7 g of a toluene solution containing 21.0 mmol of aluminum and 2.41 g of a cyclohexane solution of sec-butyllithium containing 4.11 mmol of sec-butyllithium were added. added.
(2) Subsequently, 28.5 g of methyl methacrylate was added thereto. The reaction solution was initially colored yellow, but became colorless after stirring for 60 minutes at room temperature.
(3) Subsequently, the internal temperature of the polymerization solution was cooled to −30 ° C., and 210 g of a mixture of n-butyl acrylate / 2-ethylhexyl acrylate (mass ratio 50/50) was added dropwise over 2 hours, and after completion of the addition Stir at −30 ° C. for 5 minutes.
(4) Furthermore, 31.8 g of methyl methacrylate was added to this, and it stirred at room temperature overnight.
(5) After adding 13.6 g of methanol to stop the polymerization reaction, the resulting reaction solution was poured into 15 kg of methanol to precipitate a white precipitate. Thereafter, the liquid precipitate was collected and dried to obtain 250 g of an acrylic triblock copolymer (I-1).

<< Synthesis Example 2 >> [Synthesis of Acrylic Triblock Copolymer (I-2)]
(1) A 3-liter cock was attached to a 2 L three-necked flask and the inside was replaced with nitrogen. Then, while stirring at room temperature, 1044 g of toluene and 34.8 g of 1,2-dimethoxyethane were added, followed by isobutylbis (2, 6-di-t-butyl-4-methylphenoxy) 34.0 g of a toluene solution containing 17.1 mmol of aluminum was added, and 1.67 g of a cyclohexane solution of sec-butyllithium containing 2.84 mmol of sec-butyllithium was further added. added.
(2) Subsequently, 22.0 g of methyl methacrylate was added thereto. The reaction solution was initially colored yellow, but became colorless after stirring for 60 minutes at room temperature.
(3) Subsequently, the internal temperature of the polymerization solution was cooled to −30 ° C., and 214 g of a mixture of n-butyl acrylate / 2-ethylhexyl acrylate (mass ratio 50/50) was added dropwise over 2 hours. Stir at −30 ° C. for 5 minutes.
(4) Furthermore, 33.8 g of methyl methacrylate was added to this, and it stirred at room temperature overnight.
(5) After adding 10.7 g of methanol to stop the polymerization reaction, the obtained reaction solution was poured into 15 kg of methanol to precipitate a white precipitate. Thereafter, the white precipitate was collected and dried to obtain 250 g of an acrylic triblock copolymer (I-2).

<< Synthesis Example 3 >> [Synthesis of Acrylic Triblock Copolymer (I-3)]
(1) A three-way cock was attached to a 2 L three-necked flask and the inside was replaced with nitrogen. Then, while stirring at room temperature, 1038 g of toluene and 43.5 g of 1,2-dimethoxyethane were added, followed by isobutylbis (2, 6-di-t-butyl-4-methylphenoxy) 37.4 g of toluene solution containing 18.8 mmol of aluminum was added, and 2.90 g of cyclohexane solution of sec-butyllithium containing 4.95 mmol of sec-butyllithium was further added. added.
(2) Subsequently, 25.4 g of methyl methacrylate was added thereto. The reaction solution was initially colored yellow, but became colorless after stirring for 60 minutes at room temperature.
(3) Subsequently, the internal temperature of the polymerization solution was cooled to −30 ° C., and 215 g of a mixture of n-butyl acrylate / 2-ethylhexyl acrylate (mass ratio 50/50) was added dropwise over 2 hours. Stir at −30 ° C. for 5 minutes.
(4) Furthermore, 29.4 g of methyl methacrylate was added to this, and it stirred at room temperature overnight.
(5) After adding 13.3 g of methanol to stop the polymerization reaction, the resulting reaction solution was poured into 15 kg of methanol to precipitate a white precipitate. Thereafter, the white precipitate was collected and dried to obtain 250 g of an acrylic triblock copolymer (I-3).

<< Synthesis Example 4 >> [Synthesis of Acrylic Diblock Copolymer (II-1)]
(1) A three-way cock was attached to a 2 L three-necked flask and the inside was replaced with nitrogen. Then, while stirring at room temperature, 903 g of toluene and 58.3 g of 1,2-dimethoxyethane were added, followed by isobutylbis (2, 6-di-t-butyl-4-methylphenoxy) 36.2 g of a toluene solution containing 18.2 mmol of aluminum was added, and 4.27 g of a cyclohexane solution of sec-butyllithium containing 7.28 mmol of sec-butyllithium was further added. added.
(2) Subsequently, 26.8 g of methyl methacrylate was added thereto. The reaction solution was initially colored yellow, but became colorless after stirring for 60 minutes at room temperature.
(3) Subsequently, the internal temperature of the polymerization solution was cooled to −30 ° C., 378 g of n-butyl acrylate was added dropwise over 2 hours, and the mixture was stirred at −30 ° C. for 5 minutes after the completion of the addition.
(4) After adding 15.0 g of methanol to stop the polymerization reaction, the resulting reaction solution was poured into 15 kg of methanol to precipitate a liquid precipitate. Thereafter, the liquid precipitate was collected and dried to obtain 380 g of an acrylic diblock copolymer (II-1).

<< Synthesis Example 5 >> [Synthesis of Acrylic Diblock Copolymer (II-2)]
(1) A three-way cock was attached to a 2 L three-necked flask and the inside was replaced with nitrogen. Then, while stirring at room temperature, 903 g of toluene and 58.3 g of 1,2-dimethoxyethane were added, followed by isobutylbis (2, 6-di-t-butyl-4-methylphenoxy) 36.2 g of a toluene solution containing 18.2 mmol of aluminum was added, and 4.27 g of a cyclohexane solution of sec-butyllithium containing 7.28 mmol of sec-butyllithium was further added. added.
(2) Subsequently, 26.8 g of methyl methacrylate was added thereto. The reaction solution was initially colored yellow, but became colorless after stirring for 60 minutes at room temperature.
(3) Subsequently, the internal temperature of the polymerization solution was cooled to −30 ° C., and 378 g of a mixture of n-butyl acrylate / 2-ethylhexyl acrylate (mass ratio 50/50) was added dropwise over 2 hours. Stir at −30 ° C. for 5 minutes.
(4) After adding 15.0 g of methanol to stop the polymerization reaction, the resulting reaction solution was poured into 15 kg of methanol to precipitate a liquid precipitate. Thereafter, the liquid precipitate was collected and dried to obtain 380 g of an acrylic diblock copolymer (II-2).

  Weight average molecular weights of acrylic triblock copolymers (I-1) to (I-3) and acrylic diblock copolymers (II-1) to (II-2) obtained in Synthesis Examples 1 to 5 above. Table 1 shows (Mw) and molecular weight distribution (Mw / Mn), the block structure, the content of each polymer block, and the configuration of the polymer block (B) or (D).

In the comparative example, the following were used as tackifying resin and plasticizer.
Tackifying resin:
・ Product name “Ysertack 311” manufactured by Euro Yser, rosin ester ・ Product name “YS resin SX100” manufactured by Yasuhara Chemical Co., Ltd., aromatic hydrocarbon resin plasticizer:
・ Product name “UP1010” manufactured by Toagosei Co., Ltd., acrylic oligomer

<< Examples 1 to 12, Comparative Examples 1 to 4 >>
Acrylic triblock copolymers (I-1) to (I-3) and acrylic diblock copolymers (II-1) to (II-2) obtained in Synthesis Examples 1 to 5 and tackifying The resin and the plasticizer were dissolved in toluene at a mass ratio shown in Table 2 below to prepare a toluene solution containing an adhesive composition having a concentration of 40% by mass. This was coated on a polyethylene terephthalate film (Toyobo Ester Film E5000, thickness 50 μm) with a coater so that the thickness of the adhesive layer after drying was 25 μm, and then the film was heated at 60 ° C. for 30 minutes. Was dried and heat-treated to produce an adhesive tape. In the evaluation of the produced adhesive tape, when it was necessary to affix to an adherend, it was affixed by reciprocating a 2 kg roller twice at a speed of 10 mm / sec.

  From the results in Table 2, from the acrylic triblock copolymers (I-1) to (I-3) and the acrylic diblock copolymers (II-1) to (II-2) that satisfy the provisions of the present invention. In Examples 1 to 12, there are no bleeds, high tack, and excellent thermal stability.

  From the results shown in Table 2, bleeding occurs when the acrylic diblock copolymer (II) is contained in excess of the specified amount of the present invention. When the acrylic diblock copolymer (II) is not contained, the tack is inferior. When a tackifying resin and / or a plasticizer is blended, problems such as deterioration in thermal stability, bleed and tackiness occur.

  The adhesive composition of the present invention has excellent transparency, bleed resistance, tack, and thermal stability. Moreover, according to the present invention, it is possible to provide an adhesive and an adhesive product excellent in the balance of these physical properties.

Claims (1)

(I) having two polymer blocks (A1) and (A2) composed of methacrylic ester units and one polymer block (B) composed of acrylate units;
Acrylic acid ester units constituting the polymer block (B) are represented by the general formula CH ₂ = CH-COOR ¹ (1) (wherein R ¹ represents an organic group having 4 to 6 carbon atoms). An acid ester (1) unit and a general formula CH ₂ ═CH—COOR ² (2) (wherein R ² represents an organic group having 7 to 12 carbon atoms) and an acrylic ester (2) unit,
(A1)-(B)-(A2) having a block structure, having a weight average molecular weight (Mw) of 40,000 to 200,000, and a polymer block (A1 in the acrylic triblock copolymer (I)) ) And (A2), the acrylic triblock copolymer (I) having a total content of 35% by mass or less, and (ii) one polymer block (C) composed of methacrylic acid ester units and acrylic One polymer block (D) consisting of acid ester units,
(C)-(D) having a block structure, having a weight average molecular weight (Mw) of 10,000 to 120,000, and the content of the polymer block (C) in the acrylic diblock copolymer (II) A pressure-sensitive adhesive composition containing 1 to 500 parts by mass of an acrylic diblock copolymer (II) having a content of 25% by mass or less.