WO2015111646A1

WO2015111646A1 - Acrylic pressure-sensitive-adhesive composition and pressure-sensitive-adhesive tape

Info

Publication number: WO2015111646A1
Application number: PCT/JP2015/051627
Authority: WO
Inventors: 隆広土井; 文弥齊木; 允喬須藤
Original assignee: ニチバン株式会社; 株式会社クラレ
Priority date: 2014-01-24
Filing date: 2015-01-22
Publication date: 2015-07-30
Also published as: CN105829479A; CN105829479B; JP6431854B2; KR20160113159A; KR102228806B1; JPWO2015111646A1

Abstract

[Problem] To provide an acrylic pressure-sensitive-adhesive composition whereby a pressure-sensitive-adhesive tape having excellent fixing properties can be obtained. [Solution] A pressure-sensitive-adhesive composition containing an ABA-type triblock copolymer (a) comprising a segment (A) having a methacrylic acid ester as the main component thereof and a segment (B) having an acrylic acid ester as the main component thereof, an ABA-type triblock copolymer (b) comprising a segment (A) having a methacrylic acid ester as the main component thereof and a segment (B) having an acrylic acid ester as the main component thereof, and a tackifying resin (c) compatible with the triblock copolymer (a) and the triblock copolymer (b) and having a softening point of 110°C or above, the segment (B) of the triblock copolymer (b) having 2-ethylhexyl acrylate as a constituent monomer, and the triblock copolymer (b) being blended in a ratio of 0.1% by mass to 50% by mass with respect to the total amount of the triblock copolymer (a) and the triblock copolymer (b).

Description

Acrylic adhesive composition and adhesive tape

The present invention relates to a pressure-sensitive adhesive composition, and more particularly to an acrylic pressure-sensitive adhesive composition and a pressure-sensitive adhesive tape formed by applying the pressure-sensitive adhesive composition to a substrate.

An acrylic pressure-sensitive adhesive containing a (meth) acrylate monomer is excellent in weather resistance, transparency, heat resistance, solvent resistance, and the like, and easily changes the adhesive force by changing the composition of the constituent monomers. In recent years, research has been actively conducted because it has the advantage of being controllable (see, for example, Patent Documents 1 to 3).

Japanese Patent Laying-Open No. 2005-307063 JP 2009-102467 A JP 2006-206624 A

Here, as a typical practical characteristic required as an adhesive tape, there are generally three basic characteristics of adhesive strength (peeling strength), tack (adhesiveness), and holding power (cohesive strength). Depending on the application, in addition to the basic characteristics, a characteristic called fixability may be required. As an example of such fixability, for example, loosening or warping of a sticking material that occurs when sticking a sticking material (for example, paper such as a poster) to a predetermined surface to be pasted (for example, a wall surface). Characteristics that can withstand vertical shearing force due to stress due to gravity or gravity (the adhesive does not peel from the surface to be applied) (hereinafter referred to as “shear fixing”), or adhesive (for example, paper such as cardboard) Characteristics) that can withstand the repulsive force that tries to return to the original shape that occurs when the shape is fixed to a predetermined shape such as a cylinder (the adhesives do not peel apart) (hereinafter referred to as “rebound fixation”) And the like). That is, the fixity here is not a characteristic of the adhesive itself, but can withstand predetermined external forces such as stress, gravity, and repulsive force as described above (even if a predetermined external force is applied) That can maintain the same state).

In the acrylic pressure-sensitive adhesive compositions described in Patent Documents 1 to 3, the basic properties required for the pressure-sensitive adhesive tape as described above are at a practical level, but the fixing property which is one of the properties described above. In particular, the acrylic adhesive composition that has been proposed so far is capable of obtaining an adhesive tape with excellent fixability. There was a problem that it was not possible.

Therefore, the present invention has been made in view of the above problems, and an object thereof is to provide an acrylic pressure-sensitive adhesive composition capable of obtaining a pressure-sensitive adhesive tape excellent in fixability.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have used an acrylic ABA type triblock copolymer as a base polymer, and at least a part of this triblock copolymer has a segment B. By using an adhesive composition containing 2-ethylhexyl acrylate as a constituent monomer and containing a polymer blend in which a predetermined tackifying resin is contained in the base polymer, excellent fixability is obtained. It has been found that an adhesive tape can be obtained, and the present invention has been completed based on this finding.

That is, the present invention provides an ABA type triblock copolymer (a) comprising a segment A mainly composed of methacrylic acid ester and a segment B mainly composed of acrylate ester,
An ABA type triblock copolymer (b) comprising a segment A mainly composed of methacrylic acid ester and a segment B mainly composed of acrylate ester, the triblock copolymer (a) and the triblock copolymer And a tackifying resin (c) having a softening point of 110 ° C. or higher that is compatible with the polymer (b) and, as a constituent monomer of the segment B of the triblock copolymer (b), acrylic acid-2- It has ethylhexyl, and the blending ratio of the triblock copolymer (b) to the total amount of the triblock copolymer (a) and the triblock copolymer (b) is 0.1% by mass or more and 50% by mass. % Of the pressure-sensitive adhesive composition.
In the pressure-sensitive adhesive composition, the triblock polymer (a) preferably has a weight average molecular weight of 60,000 or more and 400,000 or less.
In the pressure-sensitive adhesive composition, the amount of the tackifier resin (c) is 15 when the total of the triblock copolymer (a) and the triblock copolymer (b) is 100 parts by mass. It is preferable that it is not less than 40 parts by mass.
In the pressure-sensitive adhesive composition, it is preferable that the constituent monomers of the segment B of the triblock copolymer (b) are n-butyl acrylate and 2-ethylhexyl acrylate.
In this case, the blending ratio of acrylic acid-n-butyl (BA) and 2-ethylhexyl acrylate (2EHA) in the segment B of the triblock copolymer (b) is BA: 2EHA = It is preferably 75:25 to 5:95.
The pressure-sensitive adhesive composition may further contain a softener (d) having compatibility with the triblock copolymer (a) and the triblock copolymer (b).
In this case, the softener (d) is a group consisting of an AB type diblock copolymer having the same segment as the segment A and segment B of the triblock copolymer (a), an acrylic oligomer, and a liquid rubber. It is preferable that it is 1 type, or 2 or more types of compounds chosen from more.
The tackifier resin (c) is preferably a rosin resin.
Moreover, this invention is an adhesive tape formed by apply | coating the adhesive composition mentioned above to the at least one surface of a base material.

According to the present invention, an acrylic triblock copolymer having a predetermined structure is used as a base polymer, and a pressure-sensitive adhesive composition containing a polymer blend in which a predetermined tackifying resin is contained in the base polymer is used. By this, it becomes possible to obtain the adhesive tape excellent in fixability.

Hereinafter, preferred embodiments of the present invention will be described in detail.

The pressure-sensitive adhesive composition according to the present invention will be described in the following order.
1 Composition of pressure-sensitive adhesive composition 1-1 Triblock copolymer (a)
1-2 Triblock copolymer (b)
1-3 Tackifying resin (c)
1-4 Optional component 2 Form of pressure-sensitive adhesive composition 3 Use of pressure-sensitive adhesive composition

<< Composition of adhesive composition >>
The pressure-sensitive adhesive composition according to the present invention contains two types of ABA-type triblock copolymers (a) and (b) as a base polymer, and further contains at least a tackifier resin (c). Yes, in addition to the properties such as adhesive strength, tack, and holding power, the above-described fixing property is excellent. Hereinafter, each component in the pressure-sensitive adhesive composition according to the present invention will be described in order.

<Triblock copolymer (a)>
The triblock copolymer (a) is an ABA type triblock copolymer composed of a segment A mainly composed of methacrylic acid ester and a segment B mainly composed of acrylate ester. Here, the “segment” in the present invention means a structural unit constituting each block in the triblock copolymer. For example, a structural unit (polymer or oligomer) A composed of monomer a and monomer b In the case of an ABA-type triblock copolymer in which a structural unit (polymer or oligomer) B consisting of the monomer B and a structural unit (polymer or oligomer) A consisting of the monomer a are sequentially bonded, the structural units A and B are segments. A and B (the same applies to the triblock copolymer (b) described later).

(Segment A)
The segment A of the triblock copolymer (a) is not particularly limited as long as it has a methacrylic acid ester as a main component monomer. Examples of such a methacrylic acid ester include methyl methacrylate, Ethyl methacrylate, isopropyl methacrylate, sec-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate, 1-methylcyclohexyl methacrylate, 2-methylcyclohexyl methacrylate, 3-methacrylic acid 3- Methylcyclohexyl, 4-methylcyclohexyl methacrylate, 2-phenoxyethyl methacrylate, 2-methoxyethyl methacrylate, 2- (N, N-dimethylamino) ethyl methacrylate, trimethacrylate Fluoromethyl, n-pentyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, tridecyl methacrylate, stearyl methacrylate, 2-methoxypentyl methacrylate, 2- (N, N-dimethylamino methacrylate) ) Pentyl, perfluoropentyl methacrylate, 2-trimethoxysilylpentyl methacrylate and the like.

Among the above monomers, in order to improve the adhesive properties (particularly the holding power at high temperature) of the adhesive auxiliary, the main constituent monomers of segment A include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, It is preferable to use a monomer such as an ester of methacrylic acid and an alcohol having 3 or less carbon atoms, such as isopropyl methacrylate.

Here, in order to say “mainly” in the present invention, it is preferable to contain 50% or more, more preferably 80% or more in terms of the monomer composition ratio (mass ratio), More preferably, the content is 90% or more.

Further, as a constituent monomer of the segment A of the triblock copolymer (a), monomers that can be used in addition to the above-mentioned methacrylic acid ester include, for example, methacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, N Methacrylamides such as isopropyl methacrylamide, N, N-dimethyl methacrylamide, N, N-diethyl methacrylamide, acrylamide, N-methyl acrylamide, N-ethyl acrylamide, N-isopropyl acrylamide, N, N-dimethyl acrylamide , Acrylamides such as N, N-diethylacrylamide, vinyl monomers having a carboxyl group such as methacrylic acid, acrylic acid, crotonic acid, maleic acid, maleic anhydride, fumaric acid, styrene, α-methyl Styrene, p- methyl and aromatic vinyl monomers such as styrene, butadiene, and conjugated diene monomers such as isoprene, ethylene, olefin or propylene, etc., .epsilon.-caprolactone, and lactones such as valerolactone.

(Segment B)
Next, the segment B of the triblock copolymer (a) is not particularly limited as long as it has an acrylate ester as a main constituent monomer. Examples of such an acrylate ester include an acrylic ester. Methyl acid, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, tert-butyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate , Dodecyl acrylate, tridecyl acrylate, stearyl acrylate, cyclohexyl acrylate, isobornyl acrylate, 2-methoxyethyl acrylate, 2- (N, N-dimethylamino) ethyl acrylate, trifluoromethyl acrylate, acrylic acid Trimethoxysil Methyl, lauryl acrylate, 2-methylbutyl, acrylic acid 4-methyl-2-pentyl, acrylic acid n- octyl, isooctyl acrylate, 2-hydroxyethyl acrylate, and 2-hydroxypropyl acrylic acid.

Moreover, as a constituent monomer of the segment B of the triblock copolymer (a), examples of monomers that can be used in addition to the above-mentioned acrylic ester include, for example, alkyl methacrylate (for example, methyl methacrylate, ethyl methacrylate, methacrylic ester). Isopropyl acid, sec-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, cyclohexyl methacrylate, and other methacrylic acid esters which are constituent monomers of segment A), methacrylamide, N-methylmethacrylamide, Methacrylamides such as N-ethylmethacrylamide, N-isopropylmethacrylamide, N, N-dimethylmethacrylamide, N, N-diethylmethacrylamide, acrylamide, N-methylacrylamido Acrylamides such as N-ethylacrylamide, N-isopropylacrylamide, N, N-dimethylacrylamide, N, N-diethylacrylamide, methacrylic acid, acrylic acid, crotonic acid, maleic acid, maleic anhydride, fumaric acid, etc. Vinyl monomers having a carboxyl group, aromatic vinyl monomers such as styrene, o-methylstyrene and p-methylstyrene, conjugated diene monomers such as butadiene and isoprene, olefins such as ethylene and propylene, and ε- Examples include lactones such as caprolactone and valerolactone.

(Weight average molecular weight)
The pressure-sensitive adhesive composition according to the present invention has excellent fixability, but this fixability is affected by the weight average molecular weight of the triblock copolymer (a). Specifically, the weight average molecular weight of the triblock copolymer (a) is preferably 60,000 or more and 400,000 or less. When the weight average molecular weight of the triblock copolymer (a) is less than 60,000, it is preferable because not only general properties such as adhesive strength, cohesive strength, and tack of the pressure-sensitive adhesive composition are lowered, but also fixing properties are lowered. Absent. In order to further improve the above characteristics, the weight average molecular weight of the triblock copolymer (a) is more preferably 110,000 or more, further preferably 130,000 or more, and 150,000. The above is particularly preferable. On the other hand, since it is necessary to provide fluidity suitable for melt molding, the weight average molecular weight of the triblock copolymer (a) is preferably set to 400,000 or less. In order to further enhance the above effect, the triblock copolymer (a) preferably has a weight average molecular weight of 300,000 or less.

In addition, as a weight average molecular weight in this invention, the value calculated | required from the polystyrene conversion molecular weight measured by gel permeation chromatography (GPC) is used.

(Hard segment content)
The content of the hard segment in the triblock copolymer (a) is preferably 5 to 30% by mass, more preferably 5 to 25% by mass based on the total mass of the triblock copolymer (a). 10 to 20% by mass is particularly preferred.

(how to get)
As the triblock copolymer (a) according to the present invention, the triblock copolymer (a) may be synthesized by polymerizing raw material monomers, or a commercially available one may be used. The polymerization method is not particularly limited, and for example, an anionic polymerization method, an atom transfer radical polymerization method (ATRP) or the like can be used. Although detailed description of each polymerization method is omitted here, as an anionic polymerization method, for example, an organic alkali metal compound is used as a polymerization initiator in the presence of a mineral salt such as an alkali metal or alkaline earth metal salt. Known methods such as a polymerization method, a method of anionic polymerization using an organic alkali metal compound as a polymerization initiator in the presence of an organoaluminum compound, and a method of anionic polymerization using an organic rare earth metal complex as a polymerization initiator can be used. For example, a known method such as a polymerization method using an organic halide or a sulfonyl halide compound as an initiator in the presence of a transition metal compound or a nitrogen-containing compound can be used. Examples of commercially available products include “Clarity (registered trademark) series” manufactured by Kuraray Co., Ltd.

<Triblock copolymer (b)>
As with the triblock copolymer (a), the triblock copolymer (b) is an ABA type triblock composed of a segment A mainly composed of a methacrylic acid ester and a segment B mainly composed of an acrylate ester. It is a copolymer. However, the triblock copolymer (b) has a structure different from that of the triblock copolymer (a) in that it has 2-ethylhexyl acrylate as a constituent monomer of the segment B.

In addition to the triblock copolymer (a) described above, the pressure-sensitive adhesive composition according to the present invention has, as a constituent monomer of the segment B of the ABA type triblock, a Tg further than that of n-butyl acrylate. By blending the copolymer (b) having a low 2-ethylhexyl acrylate, the fixability can be remarkably improved in addition to the properties generally required as an adhesive such as adhesive strength, tack and holding power. . In particular, as an effect obtained by blending the triblock copolymer (b), the original (such as paper such as cardboard), which occurs when the patch (such as cardboard) is fixed in a predetermined shape such as a cylindrical shape, The characteristics (resilience fixability) that can withstand the repulsive force to return to the shape (the adhesives do not peel apart) can be remarkably improved. Hereinafter, the triblock copolymer (b) will be described in detail.

(Segment A)
Since the segment A of the triblock copolymer (b) is the same as the segment A of the triblock copolymer (a) described above, detailed description thereof is omitted here. In the pressure-sensitive adhesive composition according to the present invention, the segment A of the triblock copolymer (a) and the segment A of the triblock copolymer (b) may be the same or different. However, considering the compatibility of the triblock copolymer (a) and the triblock copolymer (b), it is preferable that the two segments A are the same.

(Segment B)
As described above, the segment B of the triblock copolymer (b) must have 2-ethylhexyl acrylate as a constituent monomer and may have “another constituent monomer”. In this case, as the “other constituent monomer”, those usable as the constituent monomer of the segment B of the triblock copolymer (a) can be used. Among these, from the viewpoint of compatibility with the triblock copolymer (a), it is preferable to use n-butyl acrylate as “another constituent monomer”. That is, it is preferable that the constituent monomer of the segment B of the triblock copolymer (b) is n-butyl acrylate and 2-ethylhexyl acrylate.

In addition, acrylate-n-butyl may be used as a constituent monomer of segment B. The blending ratio of acrylic acid-n-butyl (BA) and acrylic acid-2-ethylhexyl (2EHA) in segment B of the triblock copolymer (b) is BA: 2EHA = 95: 5-0 : 100 is preferred. By making a compounding ratio into this range, the improvement effect of the fixability of an adhesive composition increases. In order to further enhance the effect of improving the fixing property, it is preferable that the blending ratio of 2EHA is high. Specifically, BA: 2EHA = 75: 25 to 5:95 is more preferable, and 60:40 to 5: More preferably, it is 95.

In the pressure-sensitive adhesive composition according to the present invention, “another constituent monomer” in the segment B of the triblock copolymer (b) and a constituent monomer of the segment B in the triblock copolymer (a) are: Although it may be the same or different, in consideration of the compatibility of the triblock copolymer (a) and the triblock copolymer (b), it is preferable that the constituent monomers of both are the same.

(Weight average molecular weight)
The weight average molecular weight of the triblock copolymer (b) in the pressure-sensitive adhesive composition according to the present invention is practically preferably 30,000 to 200,000, more preferably 150,000, from the viewpoint of stable production. It is as follows. When the weight average molecular weight is less than 30,000, the adhesive strength is too low and there is a problem in practical use. When the weight average molecular weight exceeds 200,000, the viscosity is too high and there is a problem in manufacturing.

(Hard segment content)
The content of the hard segment in the triblock copolymer (b) is preferably 10 to 40% by mass, more preferably 15 to 30% by mass based on the total mass of the triblock copolymer (b). 20 to 25% by mass is particularly suitable.

(how to get)
As the triblock copolymer (b) according to the present invention, the triblock copolymer (b) may be synthesized by polymerizing raw material monomers, or a commercially available one may be used. Although it does not restrict | limit especially as a polymerization method, As a specific example of a polymerization method, it is the same as that of a triblock copolymer (a). Examples of commercially available products include “Clarity (registered trademark) series” manufactured by Kuraray Co., Ltd.

(Compounding ratio of triblock copolymer (a) and triblock copolymer (b))
In the pressure-sensitive adhesive composition according to the present invention, the mixing ratio of the triblock copolymer (a) and the triblock copolymer (b) (triblock copolymer ( The blending ratio of the triblock copolymer (b) to the total amount of a) and the triblock copolymer (b) must be 0.1% by mass or more. Thereby, the improvement effect of the fixability of an adhesive composition increases notably. On the other hand, if the blending ratio of the triblock copolymer (b) is too high, the performance as a base polymer is reduced, so that not only general properties such as adhesive strength, tack, and holding power are reduced, The fixability of the pressure-sensitive adhesive composition also decreases. Therefore, it is preferable to increase the blending ratio of the triblock copolymer (a). Specifically, the blending ratio of the triblock copolymer (b) needs to be 50% by mass or less. The lower limit of the blending amount of the triblock copolymer (b) is preferably 1% by mass or more and more preferably 3% by mass or more in order to further enhance the effect of improving the fixability. Yes, more preferably 5% by mass or more, and particularly preferably 10% by mass or more. On the other hand, the upper limit of the amount of the triblock copolymer (b) is preferably set to 40% by mass or less in order to further enhance the effect of improving the fixability and suppress the decrease in general characteristics. It is more preferable to set it as 30 mass% or less, and it is especially preferable to set it as 20 mass% or less.

<Tackifying resin (c)>
The pressure-sensitive adhesive composition according to the present invention further contains a tackifying resin (c) as an essential component in addition to the above-described base polymer. Only the above-mentioned triblock copolymer (a) and triblock copolymer (b) can have a function as a general pressure-sensitive adhesive composition, but have low adhesive force and are not practical. Therefore, the pressure-sensitive adhesive composition according to the present invention increases the adhesive strength to a practically sufficient level by containing the tackifier resin (c), and is generally used as a pressure-sensitive adhesive such as adhesive strength, tack, and holding power. It meets the characteristics.

(Compatibility with triblock copolymer)
Here, the tackifying resin (c) is formed so that the triblock copolymer (a) and the triblock copolymer (b) can form a polymer blend with the triblock copolymer (a) and the triblock copolymer (a). This resin is compatible with the coalescence (b). The resin having such compatibility is not particularly limited, and for example, rosin type, terpene type and the like can be used. Examples of the rosin resin include rosin ester, hydrogenated rosin ester, disproportionated rosin ester, polymerized rosin ester, gum rosin, tall oil rosin, maleated rosin, maleic acid modified rosin, etc. Examples thereof include terpene phenol resins, hydrogenated terpene phenol resins, aromatic modified terpene resins, aromatic modified hydrogenated terpene resins, hydrogenated terpene resins, α-pinene, β-pinene, limonene and the like. Among these, from the viewpoint of improving the fixability, it is preferable to use a rosin resin as the tackifier resin according to the present invention.

(Softening point)
Further, as the tackifier resin (c) according to the present invention, at least one resin having a softening point of 100 ° C. or higher is used. By blending such a tackifying resin (c) having a high softening point, the fixability can be remarkably improved in addition to the properties generally required as an adhesive such as adhesive strength, tack, and holding power. In particular, when a sticking material (for example, paper such as a poster) is applied to a predetermined surface to be applied (for example, a wall surface) by blending a tackifying resin (c) having a high softening point (100 ° C. or higher). The characteristics (shear fixability) that can withstand the stress due to the slack or warping of the patch and the vertical shearing force due to gravity (the patch does not peel from the surface to be pasted) can be significantly improved. From the viewpoint of further improving this property, the softening point of the tackifier resin (c) is preferably 110 ° C. or higher, and more preferably 120 ° C. or higher.

On the other hand, if the softening point of the tackifying resin (c) is too high, the resin becomes too hard to obtain a viscosity suitable as an adhesive. Therefore, the softening point of the tackifier resin (c) is preferably 200 ° C. or less, more preferably 170 ° C. or less, further preferably 165 ° C. or less, and most preferably 160 ° C. or less. preferable. The tackifying resin having a suitable softening point is preferably a main component (50% by mass or more based on the total mass of all tackifying resins).

(Mixing amount)
The amount of the tackifier resin (c) is 15 parts by mass or more and 40 parts by mass or less when the total of the triblock copolymer (a) and the triblock copolymer (b) is 100 parts by mass. It is preferable. When the compounding amount of the tackifying resin (c) is less than 15 parts by mass, the effect of adding it (adhesive force or improvement effect of fixability) may be insufficient. From the viewpoint of remarkably improving the adhesive strength and fixability of the pressure-sensitive adhesive composition, it is more preferable that the amount of the tackifier resin (c) is 25 parts by mass or more. On the other hand, if the amount of the tackifier resin (c) exceeds 40 parts by mass, the tack may be reduced.

<Optional component: Softener (d)>
The pressure-sensitive adhesive composition according to the present invention may further contain a softener (d) as an optional component in addition to the above-described base polymer. Only the above-mentioned triblock copolymer (a) and triblock copolymer (b) can have a function as the pressure-sensitive adhesive composition according to the present invention, but the adhesive force is low and practically insufficient. There is a case. Accordingly, the pressure-sensitive adhesive composition according to the present invention contains the softener (d), thereby increasing the adhesive strength to a practically sufficient level, and general properties as a pressure-sensitive adhesive such as adhesive strength, tack, and holding power. To meet.

(Compatibility with triblock copolymer)
Here, the softening agent (d) is a triblock copolymer (a) and a triblock copolymer so that a polymer blend can be formed with the triblock copolymer (a) and the triblock copolymer (b). This resin is compatible with (b). The compound having such compatibility is not particularly limited. For example, an AB type diblock copolymer having segments similar to the segment A and the segment B of the triblock copolymer (a). , Acrylic polymer, acrylic oligomer, liquid rubber (for example, polybutene, polyisobutylene, polyisoprene), process oil, phthalic acid esters, adipic acid esters, sebacic acid esters, aliphatic esters, polyethers, etc. It is done. These compounds may be used individually by 1 type, and may be used in combination of 2 or more type. Among these compounds, since the compatibility with the triblock copolymer (a) and the triblock copolymer (b) is good, the diblock copolymer is used alone, or the diblock copolymer and the acrylic oligomer are used. It is particularly preferable to use in combination.

The diblock copolymer is not particularly limited as long as it has the same segment as the segment A and segment B of the triblock copolymer (a) described above. However, in consideration of the compatibility of the softener (d) with the triblock copolymer (a) and the triblock copolymer (b), the segments A and B of the diblock copolymer are respectively separated from the triblock copolymer. It is preferable to consist of the same constituent monomer as the segments A and B of the polymer (a). In this case, the constituent monomer of the segment A of the triblock copolymer (b) is the same as the segment A of the diblock copolymer and the triblock copolymer, and the segment B of the triblock copolymer (b). It is preferable that the above “other constituent monomer” is the same as the segment B of the diblock copolymer and the triblock copolymer because the compatibility becomes the highest. The acrylic oligomer and liquid rubber are preferable because the compatibility with the triblock copolymer (a) and the triblock copolymer (b) is increased.

(Mixing amount)
From the viewpoint of improving the tackiness of the pressure-sensitive adhesive composition, a softener (d) may be blended. The blending amount of the softening agent (d) is preferably 250 parts by mass or less when the total of the triblock copolymer (a) and the triblock copolymer (b) is 100 parts by mass. When the blending amount of the softening agent (d) exceeds 250 parts by mass, the holding power of the pressure-sensitive adhesive composition may be lowered. Therefore, in order to improve the fixability, the amount is more preferably 200 parts by mass or less, and further preferably 150 parts by mass or less. In addition, a lower limit is not specifically limited, For example, it is 50 mass parts.

<Optional components: Other>
In addition, the pressure-sensitive adhesive composition according to the present invention includes a filler, an antioxidant, a heat stabilizer, an ultraviolet absorber, a light stabilizer, an antistatic agent, a flame retardant, and foaming as long as the effects of the present invention are not impaired. You may add 1 type, or 2 or more types of other additives, such as a coloring agent, a coloring agent, and a dyeing | staining agent.

<< Form of pressure-sensitive adhesive composition >>
As described above, the composition of the pressure-sensitive adhesive composition according to the present invention has been described in detail. The pressure-sensitive adhesive composition includes the above-described triblock copolymer (a), triblock copolymer (b), and tackifier resin ( c), a solution-type pressure-sensitive adhesive composition in which the softener (d) and an optional component (pressure-sensitive adhesive material) are dissolved in a predetermined solvent, or a hot melt obtained by melting and kneading the pressure-sensitive adhesive material. It can also be set as a pressure-sensitive adhesive composition. In addition, as a solvent used in the case of a solution type, organic solvents, such as toluene and ethyl acetate, can be used, for example.

≪Use of adhesive composition≫
The pressure-sensitive adhesive composition according to the present invention as described above can be used for applications such as pressure-sensitive adhesive tapes (one side or both sides). Below, the double-sided adhesive tape formed by apply | coating the adhesive composition mentioned above to both surfaces of a base material as an example of the use of the adhesive composition which concerns on this invention is demonstrated. In the case of a single-sided adhesive tape, the same applies except that the adhesive is applied to one side of the substrate.

In the double-sided pressure-sensitive adhesive tape to which the pressure-sensitive adhesive composition according to the present invention is applied, the above-mentioned pressure-sensitive adhesive composition is applied to both surfaces of a substrate, and the surface of the pressure-sensitive adhesive composition is a release paper as necessary. Is attached.

The substrate is not particularly limited as long as it is in the form of a film or sheet to which the adhesive composition can be applied, for example, paper such as kraft paper, Japanese paper, crepe paper, rayon, cotton, acetate, Nonwoven fabric made of polyethylene (PE), polypropylene (PP), etc., cellophane, vinyl chloride, PE, expanded polypropylene (OPP), polyethylene terephthalate (PET), tetrafluoroethylene, polyimide, polycarbonate (PC), polystyrene (PS) Resin films such as polyurethane, PE, butyl rubber, metal foils such as aluminum and copper, rubber sheets such as natural rubber, SBR, butyl rubber, and the like.

The method for applying the pressure-sensitive adhesive composition to the base material is not particularly limited, but a method of applying the pressure-sensitive adhesive material by dissolving it in an organic solvent (spreading method), thinning with a plurality of hot rolls, and applying Well-known techniques such as a technique (calender method) for applying and a method of applying a hot-melt adhesive material (hot-melt method) can be used.

Next, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to these examples.

<Description of raw materials>
Double-sided pressure-sensitive adhesive tapes of Examples 1-27 and Comparative Examples 1-7 were prepared using the following raw materials.
[Triblock copolymer (a)]
Triblock copolymer (a-1): Methyl methacrylate (MMA) / n-butyl acrylate (n-BA) copolymer (triblock, hard segment (segment A) is MMA, soft segment (segment B) ) Is n-BA, hard segment content 16% by mass), molecular weight 140,000
Triblock copolymer (a-2): Methyl methacrylate (MMA) / n-butyl acrylate (n-BA) copolymer (triblock, hard segment (segment A) is MMA, soft segment (segment B) ) Is n-BA, hard segment content 22% by mass), molecular weight 115,000
Triblock copolymer (a-3): Methyl methacrylate (MMA) / n-butyl acrylate (n-BA) copolymer (triblock, hard segment (segment A) is MMA, soft segment (segment B) ) Is n-BA, hard segment content 23% by mass), molecular weight 75,000
Triblock copolymer (a-4): Methyl methacrylate (MMA) / n-butyl acrylate (n-BA) copolymer (triblock, hard segment (segment A) is MMA, soft segment (segment B) ) Is n-BA, hard segment content is 12% by mass), molecular weight is 180,000
[Triblock copolymer (b)]
Triblock copolymer (b-1): Methyl methacrylate / n-butyl acrylate / 2-ethylhexyl acrylate (2EHA) copolymer (triblock, MMA for hard segment, n-BA for soft segment and 2EHA) N-BA: 2EHA = 50: 50 (mass ratio), hard segment content 23 mass%) Molecular weight 100,000
Triblock copolymer (b-2): Methyl methacrylate / n-butyl acrylate / 2-ethylhexyl acrylate (2EHA) copolymer (triblock, MMA for hard segment, n-BA and 2EHA for soft segment) N-BA: 2EHA = 20: 80 (mass ratio), hard segment content 23 mass%) Molecular weight 100,000
Triblock copolymer (b-3): Methyl methacrylate / n-butyl acrylate / 2-ethylhexyl acrylate (2EHA) copolymer (triblock, MMA for hard segment, n-BA and 2EHA for soft segment) N-BA: 2EHA = 80: 20 (mass ratio), hard segment content 23 mass%) Molecular weight 100,000
Triblock copolymer (b-4): Methyl methacrylate / 2-ethylhexyl acrylate (2EHA) copolymer (triblock, MMA for hard segment, 2EHA for soft segment, 23% by mass of hard segment) Molecular weight 80,000
[Tackifying resin (c)]
Pencel A: Rosin ester (softening point 100 ° C)
Pencel D-125: Polymerized rosin ester (softening point 125 ° C.)
Pencel D-135: Polymerized rosin ester (softening point 135 ° C.)
Pencel D-160: Polymerized rosin ester (softening point 160 ° C.)
YS Polystar G150: terpene phenol copolymer (softening point 150 ° C.)
[Softener (d)]
Clarity LA1114: Methyl methacrylate / n-butyl acrylate copolymer (diblock, hard segment MMA, soft segment n-BA)
Alfon (registered trademark) UP-1000: Non-functional group type acrylic polymer

<Manufacturing method>
Double-sided pressure-sensitive adhesive tapes were prepared by the melting method with the above raw materials in the blending amounts shown in Table 1 below (unit: parts by mass). Specifically, the raw materials were added to toluene in the blending amounts shown in Table 1 below, and the raw materials were dissolved by stirring to prepare a solution-type pressure-sensitive adhesive composition (solid content concentration 50% by mass). Next, the obtained pressure-sensitive adhesive composition was glued to release paper with an applicator. After drying in an oven at 100 ° C. for 3 minutes, the nonwoven fabric (I) was bonded to the pressure-sensitive adhesive composition. Subsequently, the pressure-sensitive adhesive composition was glued on the release paper in the same manner as described above, dried, and then bonded to the nonwoven fabric side of (I) to prepare a double-sided pressure-sensitive adhesive tape. The coating amount of the pressure-sensitive adhesive composition was 25 g / m ^{2 on} both sides. Finally, in order to improve the anchoring between the adhesive and the nonwoven fabric, thermal lamination at 120 ° C. was performed, and double-sided adhesive tapes of Examples 1 to 27 and Comparative Examples 1 to 7 were produced.

<Evaluation method>
With respect to the double-sided pressure-sensitive adhesive tapes of Examples 1 to 27 and Comparative Examples 1 to 7 produced as described above, each characteristic was evaluated by the following methods.
(1) Basic characteristics (SUS adhesive strength, probe tack, ball tack, glass holding power)
The basic characteristics were measured according to JIS Z 0237. However, in the evaluation of SUS adhesive strength, a method different from the method defined in JIS Z 0237 was used as a test plate and a pressure bonding method. Specifically, in the evaluation of SUS adhesive strength, a SUS304 steel plate defined in JIS G 4305 was subjected to surface polishing finishing as a test plate. Further, at the time of pressure bonding, a 2000 g roller was reciprocated once at a speed of 300 mm / min, and left for 20 to 40 minutes after pressure bonding, and then the adhesive strength was measured (others are the same as JIS Z 0237).
(2) Shear Fixability Test A 15 mm square double-sided adhesive tape was attached to the four corners of ASKUL color-coated paper (poster) having an A2 size, a basis weight of 87 g / m ² and a thickness of 125 μm. Thereafter, the color coated paper was strongly pressed and stuck to the wall on which the Sangetsu vinyl chloride wallpaper SP7204 was pasted, and left in an environment of 40 ° C. and about 10% RH for 12 hours or longer. At this time, after the sticking, the drop time from the wall to the poster falling was measured and evaluated according to the following criteria.
A: Fall time of 4 days or more B: Drop time of 24 hours or more and less than 4 days C: Drop time of 5 hours or more and less than 24 hours D: Drop time of less than 5 hours (3) Rebound fixing test A4 size, basis weight Attach a 15 mm wide double-sided adhesive tape to the edge of the short side of the Imamura paper board cover (thick paper) of 500 g / m ² , roll the cardboard along a paper tube with a diameter of 78 mm, and Bonding and creating a cylinder. At this time, after sticking, the peeling time until the cylinder opened (the bonded part of the cardboard peeled) was measured and evaluated according to the following criteria.
A: Peeling time is 6 days or more B: Peeling time is 24 hours or more and less than 6 days C: Peeling time is 5 hours or more and less than 24 hours D: Peeling time is less than 5 hours

<Evaluation results>
By adding PMMA / Pn-BA-2EHA / PMMA in addition to the PMMA / Pn-BA / PMMA triblock copolymer, the cardboard is fixed in a cylindrical shape while maintaining the adhesive strength, tack and holding force. It has been found that the rebound fixing ability that can withstand the repulsion force that peels off such as a paper craft is improved significantly. Regarding the basic characteristics, in Example 1, the SUS adhesive strength was 7.6 [N / 15 mm], the probe tack was 9.3 [N / 5 mmφ], and the ball tack was No. 12 and the glass holding power was 0.2 [mm / 15 · 20 · 1 kg · 1 h]. Further, in other examples and comparative examples, almost the same results as in Example 1 were obtained.

In addition to rebound fixability, the addition of tackifying resins with a high softening point improves shear fixability that can withstand the stress caused by paper slack and warping, such as posters, and vertical shearing force due to gravity. I found out that

The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above-described embodiment. That is, it is understood that other forms or various modifications that can be conceived by those skilled in the art within the scope of the invention described in the claims belong to the technical scope of the present invention.

Claims

An ABA type triblock copolymer (a) comprising a segment A mainly composed of methacrylic acid ester and a segment B mainly composed of acrylate ester;
An ABA type triblock copolymer (b) comprising a segment A mainly composed of methacrylic acid ester and a segment B mainly composed of acrylate ester;
A tackifying resin (c) having a softening point of 110 ° C. or more compatible with the triblock copolymer (a) and the triblock copolymer (b);
Containing
As a constituent monomer of segment B of the triblock copolymer (b), there is 2-ethylhexyl acrylate,
The mixing ratio of the triblock copolymer (b) to the total amount of the triblock copolymer (a) and the triblock copolymer (b) is 0.1% by mass or more and 50% by mass or less. Adhesive composition.
The pressure-sensitive adhesive composition according to claim 1, wherein the triblock polymer (a) has a weight average molecular weight of 60,000 or more and 400,000 or less.
The amount of the tackifying resin (c) is 15 parts by mass or more and 40 parts by mass or less when the total of the triblock copolymer (a) and the triblock copolymer (b) is 100 parts by mass. The pressure-sensitive adhesive composition according to any one of claims 1 to 3, wherein
The pressure-sensitive adhesive composition according to any one of claims 1 to 3, wherein the constituent monomer of the segment B of the triblock copolymer (b) is n-butyl acrylate and 2-ethylhexyl acrylate. .
The blending ratio of acrylic acid-n-butyl (BA) and acrylic acid-2-ethylhexyl (2EHA) in the segment B of the triblock copolymer (b) is BA: 2EHA = 75: 25 to The pressure-sensitive adhesive composition according to claim 4, which is 5:95.
The pressure-sensitive adhesive composition according to any one of claims 1 to 5, further comprising a softener (d) having compatibility with the triblock copolymer (a) and the triblock copolymer (b). object.
The softening agent (d) is selected from the group consisting of an AB-type diblock copolymer having the same segment as the segment A and segment B of the triblock copolymer (a), an acrylic oligomer, and a liquid rubber. The pressure-sensitive adhesive composition according to claim 6, which is a seed or two or more compounds.
A pressure-sensitive adhesive tape obtained by applying the pressure-sensitive adhesive composition according to any one of claims 1 to 7 to at least one surface of a substrate.