JP2022189944A - Hot melt type adhesive composition - Google Patents

Abstract

To provide a hot melt type adhesive composition which is excellent in adhesive force to various adherends, and can suppress an adhesive residue on an adherend when the hot melt type adhesive composition is peeled off.SOLUTION: A hot melt type adhesive composition contains a styrene-based block copolymer (A), an acrylic block copolymer (B), a tackifier resin (C), and a softening agent (D), and satisfies conditions (1) to (6).SELECTED DRAWING: None

Description

The present invention relates to a hot-melt pressure-sensitive adhesive composition.

Hot-melt adhesives are adhesives that are obtained by coating in a heated and melted state and then cooling, and since no solvent is used in the manufacturing process, they are highly safe and environment-friendly adhesives. Therefore, hot-melt pressure-sensitive adhesives are widely used in the fields of paper processing, woodworking, electronics, and the like.

Hot-melt pressure-sensitive adhesives include, for example, hot-melt pressure-sensitive adhesives using styrene-based elastomers. Hot-melt pressure-sensitive adhesives using styrene-based elastomers have good adhesion to polymethyl methacrylate resin plates (PMMA plates) and stainless steel plates (SUS plates), but have high adhesion enhancement at relatively high temperatures. Therefore, there is a problem that an adhesive residue is generated.
On the other hand, hot-melt type adhesives using acrylic block copolymers are less likely to cause the problem of adhesive residue due to their low tack enhancement, but their adhesive strength to non-polar resins such as polyethylene (PE) is weak. However, there is a problem that usable adherends are limited.

In order to solve these problems, hot-melt pressure-sensitive adhesives have been extensively developed. For example, Patent Document 1 proposes a hot-melt pressure-sensitive adhesive in which a styrene block copolymer and an acrylic block copolymer are combined.

International Publication No. 2015/076332

In the hot-melt pressure-sensitive adhesive described in Patent Document 1, there is a problem that the styrene-based block copolymer and the acrylic-based block copolymer are not uniformly compatible, and sufficient adhesive strength cannot be obtained. rice field.

The present invention has been made in view of the above-described problems of the prior art, and provides a hot-melt pressure-sensitive adhesive composition that exhibits excellent adhesion to various adherends and suppresses adhesive residue on the adherend when the hot-melt pressure-sensitive adhesive composition is peeled off. An object of the present invention is to provide a hot-melt pressure-sensitive adhesive composition capable of

As a result of studies by the present inventors, among styrenic block copolymers, styrenic block copolymers having high fluidity have high affinity with acrylic block copolymers and are easily compatible with each other. I got the knowledge. As a result of further investigation, it was found that the styrene block copolymer and the acrylic block copolymer having high fluidity satisfy specific melt viscosity conditions, and furthermore, by blending materials that satisfy various conditions, moderate It has been found that the tackiness can be adjusted and that it has excellent tackiness to a wide variety of adherends. Further, the inventors have found that the resulting hot-melt pressure-sensitive adhesive composition can also suppress adhesive residue, and completed the present invention.

The gist of the present invention is the following [1] to [4].
[1] Contains a styrene block copolymer (A), an acrylic block copolymer (B), a tackifying resin (C) and a softening agent (D), and satisfies the following conditions (1) to (6) A hot-melt pressure-sensitive adhesive composition characterized by:
<Condition (1)>
The melt viscosity (P A ) of the styrenic block copolymer (A) at 190° C. and the melt viscosity (P _B ) of the acrylic block copolymer ( _B ) at 190° C. have a relationship of P _A <P _B. meet.
<Condition (2)>
The mass ratio [(A)/(B)] of the content of the styrene block copolymer (A) to the acrylic block copolymer (B) is 10/90 to 95/5.
<Condition (3)>
The styrenic block copolymer (A) comprises one or more polymer blocks (a11) containing a structural unit derived from a styrene compound and a polymer block (a12) containing a structural unit derived from a conjugated diene compound. It is a hydrogenated product of the block copolymer (P1) having one or more, and the melt viscosity (P _A ) measured at a temperature of 190° C. and a shear rate of 121.6 (1/sec) in accordance with ISO 11443:1995 is 100 Pa·s or more and less than 600 Pa·s.
<Condition (4)>
The acrylic block copolymer (B) comprises one or more polymer blocks (b11) containing a structural unit derived from an acrylic acid ester and a polymer block (b12) containing a structural unit derived from a methacrylic acid ester. having one or more, a number average molecular weight (Mn) of 50,000 to 300,000, and a content of the polymer block (b12) in the acrylic block copolymer (B) of 5 to 30% by mass; is.
<Condition (5)>
The tackifying resin (C) is a tackifying resin having a softening point of 80 to 160° C., and is a rosin-based resin, a terpene-based resin, a phenol-based resin, a terpene-phenol-based resin, a hydrogenated petroleum-based resin, or a styrene-based resin. , xylene-based resins, hydrogenated aromatic copolymers and coumarone-indene-based resins.
<Condition (6)>
The softener (D) is one or more selected from the group consisting of liquid acrylic polymers, acrylic oligomers, paraffinic process oils, naphthenic process oils and aromatic process oils.
[2] The hot-melt pressure-sensitive adhesive composition according to [1] above, wherein the acrylic block copolymer (B) has a melt viscosity (P _B ) at 190°C of more than 100 Pa s and not more than 1,200 Pa s. thing.
[3] The hot melt according to [1] or [2], wherein the content of the styrenic block copolymer (A) contained in the hot melt adhesive composition is 3 to 70% by mass. mold adhesive composition.
[4] Any one of the above [1] to [3], wherein the content of the acrylic block copolymer (B) contained in the hot-melt pressure-sensitive adhesive composition is 0.5 to 50% by mass. The hot-melt pressure-sensitive adhesive composition according to .

According to the present invention, there is provided a hot-melt pressure-sensitive adhesive composition that exhibits excellent adhesive strength to various adherends and can suppress adhesive residue on adherends when the hot-melt pressure-sensitive adhesive composition is peeled off. can do.

[Hot-melt adhesive composition]
The hot-melt pressure-sensitive adhesive composition of the present invention comprises a styrene block copolymer (A), an acrylic block copolymer (B), a tackifying resin (C) and a softening agent (D), under the following conditions ( 1) to (6) are satisfied.

<Condition (1)>
In the present invention, the melt viscosity (P A ) of the styrene block copolymer (A) at a temperature of 190 ° C. and the melt viscosity (P _B ) of the acrylic block copolymer ( _B ) at a temperature of 190 ° C. are P It is characterized by satisfying the relationship _A < _PB .
When the melt viscosity (P _A ) and the melt viscosity (P _B ) satisfy the above relationship, the compatibility between the styrenic block copolymer (A) and the acrylic block copolymer (B) is improved. As a result, the adhesiveness of the hot-melt adhesive composition of the present invention is improved. In addition, since the tackiness can be adjusted to an appropriate range, adhesive residue on the adherend can be suppressed. From these points of view, P _B is preferably greater than _PA by 5 Pa·s or more, more preferably by 50 Pa·s or more, and even more preferably by 100 Pa·s or more.
In this specification, “melt viscosity at 190°C (P _A )” and “melt viscosity at 190°C (P _B )” are based on ISO 11443:1995, at a temperature of 190°C and a shear rate of 121.6 (1/ sec) means the melt viscosity measured in seconds.

<Condition (2)>
In the present invention, the mass ratio [(A)/(B)] of the content of the styrene block copolymer (A) to the acrylic block copolymer (B) is 10/90 to 95/5. Characterized by
When the mass ratio is within the range, the styrene block copolymer (A) and the acrylic block copolymer (B) are more likely to be uniformly compatible with each other, so that the adhesiveness of the hot-melt pressure-sensitive adhesive composition increases. improves. From this viewpoint, the mass ratio [(A)/(B)] is 10/90 to 95/5, preferably 20/80 to 90/10, and 30/70 to 85/15. is more preferred, and 40/60 to 80/20 is even more preferred.

<Condition (3)>
In the present invention, the styrene block copolymer (A) comprises one or more polymer blocks (a11) containing a structural unit derived from a styrene compound and a polymer block containing a structural unit derived from a conjugated diene compound. It is a hydrogenated product of the block copolymer (P1) having one or more (a12), and the melt viscosity measured at a temperature of 190 ° C. and a shear rate of 121.6 (1/sec) in accordance with ISO 11443:1995 (P _A ) is 100 Pa·s or more and less than 600 Pa·s.

<Condition (4)>
In the present invention, the acrylic block copolymer (B) comprises one or more polymer blocks (b11) containing a structural unit derived from an acrylic acid ester, and a polymer block containing a structural unit derived from a methacrylic acid ester. (b12) at least one, the number average molecular weight (Mn) is 50,000 to 300,000, and the content of the polymer block (b12) in the acrylic block copolymer (B) is 5 It is characterized by being ~30% by mass.

<Condition (5)>
The tackifier resin (C) of the present invention is a tackifier resin having a softening point of 80 to 160 ° C., which includes a rosin-based resin, a terpene-based resin, a phenol-based resin, a terpene-phenol-based resin, a hydrogenated petroleum-based resin, Two or more selected from the group consisting of styrene-based resins, xylene-based resins, hydrogenated aromatic copolymers and coumarone-indene-based resins are used.

<Condition (6)>
The softening agent (D) of the present invention is characterized by using one or more selected from the group consisting of liquid acrylic polymers, acrylic oligomers, paraffinic process oils, naphthenic process oils and aromatic process oils. By using the above softener in the present invention, the fluidity of the hot-melt pressure-sensitive adhesive composition is improved, and each component tends to be uniformly compatible. improves.

<Styrene block copolymer (A)>
The hot-melt pressure-sensitive adhesive composition of the present invention contains a styrenic block copolymer (A). In the present invention, by using the styrenic block copolymer (A), the adhesiveness to various adherends can be improved. The styrenic block copolymer (A) used in the present invention is a polymer containing one or more polymer blocks (a11) containing a structural unit derived from a styrenic compound and a structural unit derived from a conjugated diene compound. It is a hydrogenated block copolymer (P1) having one or more blocks (a12). The styrenic block copolymer (A) may be used alone or in combination of two or more.

[Polymer block (a11)]
The polymer block (a11) contained in the block copolymer (P1) contains a structural unit derived from a styrene compound. Examples of the styrene compounds include styrene, α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 4-propylstyrene, 4-t-butylstyrene, 4-cyclohexylstyrene and 4-dodecyl. Styrene, 2,4-dimethylstyrene, 2,4-diisopropylstyrene, 2,4,6-trimethylstyrene, 2-ethyl-4-benzylstyrene, 4-(phenylbutyl)styrene, 1-vinylnaphthalene, 2-vinyl naphthalene, vinylanthracene, N,N-diethyl-4-aminoethylstyrene, vinylpyridine, 4-methoxystyrene, monochlorostyrene, dichlorostyrene and divinylbenzene. These styrenic compounds may be used singly or in combination of two or more. Among these, the styrenic compound is preferably styrene, α-methylstyrene, and 4-methylstyrene, more preferably styrene.

The polymer block (a11) may contain a structural unit derived from a monomer other than a styrenic compound, for example, another monomer such as a conjugated diene constituting the polymer block (a12) described later. good. However, the content of the structural unit derived from the styrene compound in the polymer block (a11) is preferably 60% by mass or more, more preferably 70% by mass or more, and 80% by mass or more. is more preferable, more preferably 90% by mass or more, and particularly preferably substantially 100% by mass.

[Polymer block (a12)]
The polymer block (a12) contained in the block copolymer (P1) contains structural units derived from the conjugated diene compound. Examples of the conjugated diene include butadiene, isoprene, 2,3-dimethyl-butadiene, 2-phenyl-butadiene, 1,3-pentadiene, 2-methyl-1,3-pentadiene, 1,3-hexadiene, 1, 3-octadiene, 1,3-cyclohexadiene, 2-methyl-1,3-octadiene, 1,3,7-octatriene, myrcene, farnesene and chloroprene. One of these conjugated dienes may be used alone, or two or more thereof may be used in combination. Among these, the conjugated dienes are preferably butadiene, isoprene, and farnesene.

The polymer block (a12) may contain a structural unit derived from a monomer other than the conjugated diene, for example, another monomer such as a styrene compound constituting the polymer block (a11). good. However, the content of the structural unit derived from the conjugated diene compound in the polymer block (a12) is preferably 60% by mass or more, more preferably 70% by mass or more, and 80% by mass or more. is more preferable, more preferably 90% by mass or more, and particularly preferably substantially 100% by mass.

(Vinylation degree of polymer block (a12))
The degree of vinylation of the structural unit derived from the conjugated diene compound contained in the polymer block (a12) is not particularly limited, but is preferably 1 to 95 mol%, more preferably 2 to 90 mol%. , more preferably 3 to 85 mol %, even more preferably 4 to 80 mol %. When the styrenic block copolymer is produced by the anionic polymerization described later, the degree of vinylation is determined by the type of solvent used, the type and amount of Lewis base used as necessary, the polymerization temperature etc. can be adjusted.

In the present invention, the “degree of vinylation” refers to 1,2-bonds in a total of 100 mol% of structural units derived from a conjugated diene compound contained in a specific polymer block (for example, polymer block (a12)). , 3,4-bonds (other than farnesene), and 3,13-bonds (for farnesene) structural units derived from conjugated diene compounds (1,4-bonds (other than farnesene) and It means the total mol % of structural units derived from conjugated diene compounds that are bonded other than 1,13-bonds (in the case of farnesene). In the present invention, the degree of vinylation obtained from the bond form of the structural units derived from the conjugated diene compound contained in the polymer before hydrogenation is the degree of vinylation of the polymer after hydrogenation. defined as The degree of vinylation is determined by 1,2-bond, 3,4-bond (other than farnesene), and 3,13-bond (for farnesene) using ¹ H-NMR in the polymer before hydrogenation. The peak derived from the structural unit derived from the bonded conjugated diene compound and the peak derived from the conjugated diene compound bonded with 1,4-bonds (other than farnesene) and 1,13-bonds (farnesene) It is calculated from the area ratio of peaks derived from structural units.

[Bond form of polymer block (a11) and polymer block (a12)]
The bonding form of the polymer block (a11) and the polymer block (a12) contained in the block copolymer (P1) is not particularly limited, and may be linear, branched, radial or a combination of two or more thereof. may Among these, a form in which each block is linked in a straight chain is preferable, and when the polymer block (a11) is represented by a11 and the polymer block (a12) by _a12 , Linkage forms represented by a12-a11) _m , a12-(a11-a12) _n , or a12-a11-a12-a11-a12 are preferred. Note that l, n and m each independently represent an integer of 1 or more.

From the viewpoint of adhesion, processability, and handleability of the resulting hot-melt pressure-sensitive adhesive composition, the bonding form is polymer block (a11), polymer block (a12), and polymer block (a11) in that order. It is preferable to have a block (two polymer blocks (a11) are bonded to both ends of the polymer block (a12)), and the styrenic block copolymer (A) is represented by a11-a12-a11. Hydrogenated triblock copolymers are preferred. In addition, from the viewpoint of fluidity, the styrene block copolymer (A) is a hydrogenated triblock copolymer represented by a11-a12-a11 and a diblock copolymer represented by a11-a12. may be a mixture of hydrogenated compounds of The mass ratio [mass ratio of the hydrogenated product of the triblock copolymer/the hydrogenated product of the diblock copolymer] in the case of a mixture is preferably 99/1 to 1/99, and 85/ It is more preferably 15 to 15/85, even more preferably 80/20 to 20/80, even more preferably 75/25 to 25/75.

Further, when the block copolymer (P1) has two or more polymer blocks (a11), each polymer block (a11) may be a polymer block composed of the same structural unit, but different structural units. It may be a polymer block consisting of. Similarly, when the block copolymer (P1) has two or more polymer blocks (a12), each polymer block (a12) may have a different structure even if it is a polymer block consisting of the same structural units. It may be a polymer block consisting of units. For example, in the two polymer blocks (a11) in the triblock copolymer represented by a11-a12-a11, the styrenic compounds used in each polymer block are of the same type. can be different.

Here, in the present specification, when polymer blocks of the same kind are linearly linked via an n-valent coupling agent or the like, the entire linked polymer blocks are treated as one polymer block. handled. Accordingly, a polymer block that should strictly be written as a11-X-a11 (X represents a coupling agent residue) is written as a11 as a whole. Polymer blocks of this type containing coupling agent residues are treated as described herein, so for example, a11-a12-X-a12-a11 containing coupling agent A block copolymer to be designated is designated a11-a12-a11 and is treated as an example of a triblock copolymer.

[Content of each polymer block]
The content of the polymer block (a11) in the block copolymer (P1) is preferably 8-45% by mass. When the content of the polymer block (a11) is within the above range, the flexibility of the hot-melt pressure-sensitive adhesive composition is improved, and the adhesion to the adherend is improved. From this point of view, the content of the polymer block (a11) is more preferably 11 to 40% by mass, even more preferably 14 to 37% by mass, even more preferably 17 to 35% by mass. preferable. When the pressure-sensitive adhesive composition of the present invention contains two or more styrenic block copolymers (A), the polymer block (a11) of at least one block copolymer (P1) is within the above range. It is more preferable that the polymer blocks (a11) of all the block copolymers (P1) are within the above range.

The content of the polymer block (a12) in the block copolymer (P1) is preferably 55 to 92% by mass, more preferably 60 to 89% by mass, and 63 to 86% by mass. is more preferable, and 65 to 83% by mass is even more preferable. When the hot-melt pressure-sensitive adhesive composition of the present invention contains two or more styrenic block copolymers (A), the polymer block (a12) of at least one block copolymer (P1) has the above range. It is preferably within the range, and more preferably within the above range for all the polymer blocks (a12) of the block copolymer (P1).

The total content of the polymer block (a11) and the polymer block (a12) in the block copolymer (P1) is preferably 80% by mass or more, more preferably 90% by mass or more, It is more preferably 95% by mass or more, and even more preferably substantially 100% by mass. When the pressure-sensitive adhesive composition of the present invention contains two or more styrenic block copolymers (A), the polymer block (a11) and polymer block (a12) of the entire mixture of block copolymers (P1) is preferably within the above range.

[Hydrogenation rate of styrene-based block copolymer (A)]
The styrenic block copolymer (A) in the present invention is a hydrogenated product of the block copolymer (P1). The hydrogenation rate of carbon-carbon double bonds in the polymer block (a12) is preferably 50 to 100 mol%, more preferably 70 to 100 mol%, from the viewpoint of heat resistance and weather resistance. preferably 75 to 100 mol%, even more preferably 80 to 100 mol%, particularly preferably 85 to 100 mol%, more particularly 90 to 100 mol% preferable. When the hot-melt pressure-sensitive adhesive composition of the present invention contains two or more styrenic block copolymers (A), the hydrogenation rate of the entire mixture of these styrenic block copolymers (A) is within the above range. More preferably, the hydrogenation rate of all the styrenic block copolymers (A) is within the above range.
When the content of the conjugated diene compound units in the polymer block (a12) is at least the lower limit, the compatibility between the styrene block copolymer (A) and the acrylic block copolymer (B) is improved. and show excellent adhesion.
The degree of hydrogenation can be calculated by measuring ¹ H-NMR of the block copolymer (P1) and the hydrogenated styrenic block copolymer (A).

[Melt viscosity of styrene block copolymer (A) at 190°C]
The melt viscosity of the styrene block copolymer (A) at 190° C. is 100 Pa·s or more and less than 600 Pa·s, preferably 200 Pa·s or more and less than 580 Pa·s. It is lower than the melt viscosity of (B) at 190°C. This further improves the compatibility between the styrene block copolymer (A) and the acrylic block copolymer (B).

From the viewpoint of compatibility, the melt viscosity of the styrenic block copolymer (A) at 190° C. is more preferably 210 to 570 Pa·s, still more preferably 220 to 560 Pa·s, and 230 It is even more preferable to be up to 560 Pa·s. When the hot-melt pressure-sensitive adhesive composition of the present invention contains two or more styrenic block copolymers (A), at least one styrenic block copolymer (A) should be within the above range. The melt viscosity of the entire mixture of these styrenic block copolymers (A) (for example, the sum of the product of the weight fraction of each copolymer and the melt viscosity) is preferably within the above range. More preferably, the melt viscosity of the mixture of the copolymers (A) is within the above range, and the melt viscosities of all the styrenic block copolymers (A) are within the above range.

[Melt viscosity of styrene-based block copolymer (A) at 230°C]
The melt viscosity at 230° C. of the styrenic block copolymer (A) is preferably 25 Pa·s or more and less than 155 Pa·s. By including the styrenic block copolymer (A) having a melt viscosity within the above range in the hot-melt pressure-sensitive adhesive composition, the processability of the hot-melt pressure-sensitive adhesive composition is further improved.
As used herein, "melt viscosity at 230°C" means melt viscosity measured at a temperature of 230°C and a shear rate of 121.6 (1/sec) in accordance with ISO11443:1995.

From the viewpoint of improving the processability and adhesion of the hot-melt pressure-sensitive adhesive composition, the melt viscosity at 230° C. of the styrenic block copolymer (A) is more preferably 30 to 152 Pa s. It is more preferably up to 149 Pa·s, even more preferably 40 to 146 Pa·s, and even more preferably 45 to 143 Pa·s. When the hot-melt pressure-sensitive adhesive composition of the present invention contains two or more styrenic block copolymers (A), at least one styrenic block copolymer (A) should be within the above range. The melt viscosity of the entire mixture of these styrenic block copolymers (A) (for example, the sum of the product of the weight fraction of each copolymer and the melt viscosity) is preferably within the above range. More preferably, the melt viscosity of the entire mixture of the copolymer (A) is within the above range, and the melt viscosity of all the styrenic block copolymers (A) is within the above range.

[Number average molecular weight of styrene block copolymer (A)]
The number average molecular weight (Mn) of the styrenic block copolymer (A) is preferably 10,000 to 500,000, more preferably 20,000 to 400,000, and more preferably 30,000 to 300. ,000, more preferably 40,000 to 100,000, even more preferably 45,000 to 75,000, and 50,000 to 70,000. Especially preferred. When the number average molecular weight of the styrene-based block copolymer (A) is at least the lower limit, the adhesiveness of the hot-melt pressure-sensitive adhesive composition to various adherends is improved. On the other hand, when the number-average molecular weight is equal to or less than the above upper limit, adhesive residue can be suppressed while maintaining the adhesive strength of the hot-melt pressure-sensitive adhesive composition.

The molecular weight distribution (Mw/Mn), which is the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the styrenic block copolymer (A), is preferably 1.00 to 6.00. It is more preferably 1.00 to 4.00, even more preferably 1.00 to 3.00, even more preferably 1.00 to 2.00, and 1.00 to 1.30 is particularly preferred. When Mw/Mn is within the above range, the styrene-based block copolymer (A) has a small variation in viscosity, is easy to handle, and suppresses bleeding out of the hot-melt pressure-sensitive adhesive composition onto an adherend. be done.
When the hot-melt pressure-sensitive adhesive composition of the present invention contains two or more styrenic block copolymers (A), the Mw/Mn of at least one styrenic block copolymer (A) is It is preferably within the range, and more preferably Mw/Mn of all the styrene block copolymers (A) are within the above range.

In this specification, the number average molecular weight (Mn) and weight average molecular weight (Mw) for the styrenic block copolymer (A) are values obtained by gel permeation chromatography in terms of standard polystyrene, and the molecular weight distribution ( Mw/Mn) is a value calculated from the values of Mw and Mn.

[Other polymer blocks]
In addition to the polymer block (a11) and the polymer block (a12), the block copolymer (P1) contains a polymer block composed of other monomers as long as the effect of the present invention is not impaired. may
Examples of the other monomers include propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1-undecene, 1-dodecene, 1- Unsaturated hydrocarbon compounds such as tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, and 1-eicosene; acrylic acid, methacrylic acid, methyl acrylate, methacrylic acid methyl, acrylonitrile, methacrylonitrile, maleic acid, fumaric acid, crotonic acid, itaconic acid, 2-acryloylethanesulfonic acid, 2-methacryloylethanesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, 2-methacrylamide- functional group-containing unsaturated compounds such as 2-methylpropanesulfonic acid, vinylsulfonic acid, vinyl acetate, and methyl vinyl ether; These may be used individually by 1 type, and may use 2 or more types together.
When the block copolymer (P1) has another polymer block, the content thereof is preferably 20% by mass or less, more preferably 10% by mass or less, and preferably 5% by mass or less. Even more preferred.

[Melt flow rate of styrene-based block copolymer (A)]
The melt flow rate (MFR) of the styrenic block copolymer (A) is preferably 30 to 260 g/10 minutes, more preferably 35 to 250 g/10 minutes, and more preferably 40 to 240 g/10 minutes. more preferably 45 to 230 g/10 minutes. When the MFR of the styrenic block copolymer (A) is within the above range, the compatibility between the styrenic block copolymer (A) and the acrylic block copolymer (B) is improved, and hot-melt adhesiveness is improved. improve the coatability of the agent composition.
The melt flow rate of the styrenic block copolymer (A) as used herein means a value measured in accordance with JIS K7210-1:2014 under conditions of a temperature of 230° C. and a load of 2.16 kg.

[Content of styrene-based block copolymer (A)]
The content of the styrenic block copolymer (A) contained in the hot-melt pressure-sensitive adhesive composition of the present invention is preferably 3 to 70% by mass, more preferably 5 to 60% by mass. , more preferably 10 to 55% by mass. When the content of the styrenic block copolymer (A) is at least the lower limit, the adhesiveness can be sufficiently improved. Improves tolerability.

[Method for producing styrene-based block copolymer (A)]
The styrenic block copolymer (A) can be obtained by, for example, a polymerization step of obtaining the block copolymer (P1) by anionic polymerization, and a carbon- It can be suitably produced by a step of hydrogenating carbon double bonds.

(Polymerization process)
The block copolymer (P1) can be produced by a solution polymerization method or a method described in JP-A-2012-502135 and JP-A-2012-502136. Among these, the solution polymerization method is preferable, and known methods such as ionic polymerization methods such as anionic polymerization and cationic polymerization, and radical polymerization methods can be applied. Among these, the anionic polymerization method is preferred. As an anionic polymerization method, in a solvent typified by a hydrocarbon, if necessary, in the presence of a Lewis base typified by an ether compound or a tertiary amine, with an anionic polymerization initiator typified by an organic alkali metal, styrene A method of sequentially adding a monomer such as a base compound and a conjugated diene to obtain a block copolymer (P1) is preferred.
The polymerization reaction can be terminated by adding an alcohol such as methanol or isopropanol as a polymerization terminator. The resulting polymerization reaction solution is poured into a poor solvent such as methanol to precipitate the block copolymer (P1), or the polymerization reaction solution is washed with water, separated, and dried to obtain the block copolymer (P1). can be isolated.

The block copolymer (P1) is obtained by polymerizing the polymer block (a11), the polymer block (a12) and the like in this order, and connecting the ends of the polymer block (a12) to each other with a halogenated silane compound, an alkoxysilyl group-containing compound You may manufacture by the method of manufacturing by coupling using a coupling agent represented by the above.

The block copolymer (P1) may be modified before the hydrogenation step described below. Functional groups that can be introduced include, for example, amino groups, alkoxysilyl groups, hydroxyl groups, epoxy groups, carboxy groups, carbonyl groups, mercapto groups, isocyanate groups, and acid anhydride groups.
As a method for modifying the block copolymer (P1), for example, before adding a polymerization terminator, a coupling agent typified by tin tetrachloride capable of reacting with the polymerization active terminal, 4,4'-bis(diethylamino ) A method of adding a polymerization terminal modifier represented by benzophenone, or other modifiers described in JP-A-2011-132298. Also, a method of grafting maleic anhydride or the like to the isolated copolymer can be used.

(Hydrogenation step)
A styrenic block copolymer (A) can be obtained by subjecting the block copolymer (P1) obtained by the above method or the modified block copolymer (P1) to a step of hydrogenation. A known method can be used for hydrogenation. For example, a hydrogenation catalyst typified by a Ziegler catalyst, a metallocene catalyst or palladium carbon is added to a solution of the block copolymer (P1) dissolved in a solvent that does not affect the hydrogenation reaction, and appropriate hydrogen It can be obtained by hydrogenation reaction at pressure and reaction temperature.

<Acrylic block copolymer (B)>
The hot-melt pressure-sensitive adhesive composition of the present invention contains an acrylic block copolymer (B). In the present invention, by using the acrylic block copolymer (B), it is possible to suppress adhesive residue on the adherend when the hot-melt pressure-sensitive adhesive composition is peeled off. As described above, the acrylic block copolymer (B) used in the present invention contains one or more polymer blocks (b11) containing a structural unit derived from an acrylic ester, and a structural unit derived from a methacrylic ester. having one or more polymer blocks (b12) that have a number average molecular weight (Mn) of 50,000 to 300,000, and the polymer block (b12) in the acrylic block copolymer (B) The content is 5 to 30% by mass.
The hot-melt pressure-sensitive adhesive composition of the present invention may contain one type of acrylic block copolymer (B) alone, or may contain two or more types.

[Polymer block (b11)]
The polymer block (b11) contains a structural unit derived from an acrylic acid ester. The acrylate ester is represented by the general formula CH ₂ ═CH—COOR ¹ (X) (wherein R ¹ represents an organic group having 4 to 6 carbon atoms) (hereinafter referred to as acrylic Also referred to as ester (b11-1)), an acrylic acid ester represented by the general formula CH ₂ ═CH—COOR ² (Y) (in formula (Y), R ² represents an organic group having 7 to 12 carbon atoms) ( Hereinafter, it is roughly classified into acrylic acid ester (b11-2)) and other acrylic acid esters.

Examples of the organic group having 4 to 6 carbon atoms represented by R ¹ in the formula (X) include alkyl groups having 4 to 6 carbon atoms such as butyl group, amyl group (pentyl group), hexyl group, and cyclohexyl group; aromatic ring groups with 6 carbon atoms such as phenyl group; organic groups containing elements other than carbon such as oxygen having a total of 4 to 6 carbon atoms such as ethoxyethyl group, tetrahydrofurfuryl group and diethylaminoethyl group; is mentioned.

Examples of the acrylic acid ester (b11-1) include n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, tert-butyl acrylate, amyl acrylate, isoamyl acrylate, n-hexyl acrylate, acrylic esters having no functional group such as cyclohexyl acrylate and phenyl acrylate; and acrylic esters having functional groups such as ethoxyethyl acrylate, tetrahydrofurfuryl acrylate, and diethylaminoethyl acrylate.

Examples of the organic group having 7 to 12 carbon atoms represented by R ² in the formula (Y) include alkyl groups having 7 to 12 carbon atoms such as ethylhexyl, octyl, decyl, isobornyl, and lauryl; organic groups containing elements other than carbon such as oxygen having a total of 7 to 12 carbon atoms such as an aromatic ring group having 7 to 12 carbon atoms such as a phenoxyethyl group;

Examples of the acrylic acid ester (b11-2) include functional groups such as 2-ethylhexyl acrylate, n-octyl acrylate, isooctyl acrylate, decyl acrylate, isobornyl acrylate, lauryl acrylate, and benzyl acrylate. acrylic acid esters having no functional groups; and acrylic acid esters having functional groups such as phenoxyethyl acrylate.

Examples of acrylic esters other than acrylic ester (b11-1) and acrylic ester (b11-2) include functional esters such as methyl acrylate, ethyl acrylate, isopropyl acrylate, n-propyl acrylate and octadecyl acrylate. acrylic acid esters having no group; acrylic acid esters having functional groups such as methoxyethyl acrylate, 2-hydroxyethyl acrylate, 2-aminoethyl acrylate and glycidyl acrylate.

Among the acrylate esters (b11-1), acrylate esters having no functional group are preferable, and n-butyl acrylate is more preferable, from the viewpoint of the flexibility of the resulting hot-melt pressure-sensitive adhesive composition.

The ratio of structural units derived from the acrylic acid ester (b11-1) contained in the polymer block (b11) [(b11-1)/(b11)×100] is preferably 10 to 100% by mass, It is more preferably 30 to 100% by mass, even more preferably 50 to 100% by mass, and may be substantially 100% by mass. Within the above range, the hot-melt pressure-sensitive adhesive composition of the present invention has good moldability.
The structural unit derived from the acrylic acid ester (b11-1) and the content of the polymer block (b11) can be determined by ¹ H-NMR, specifically by the method described in Examples.

Among the acrylic acid esters (b11-2), the larger the polarity difference between the polymer block (b11) and the polymer block (b12), the greater the phase difference between the polymer block (b11) and the polymer block (b12). From the viewpoint of clearer separation and high cohesive strength when used as a hot-melt pressure-sensitive adhesive composition, acrylic acid esters having no functional group are preferred, such as 2-ethylhexyl acrylate, n-octyl acrylate, Isooctyl acrylate and benzyl acrylate are more preferred. 2-Ethylhexyl acrylate is more preferable because the resulting hot-melt pressure-sensitive adhesive composition exhibits stable durability over a wide temperature range.

The acrylic acid esters may be used alone or in combination of two or more. The content of the acrylic ester-derived structural unit in the polymer block (b11) is preferably 60% by mass or more, more preferably 80% by mass or more, and 90% by mass or more. is more preferable, and may be substantially 100% by mass.

Among these, the acrylic ester improves the compatibility between the acrylic block copolymer (B) and the styrene block copolymer (A), and from the viewpoint of expressing stable adhesion and workability. , acrylate (b11-1) and acrylate (b11-2), and more preferably acrylate (b11-1).

Further, from the above viewpoint, the acrylic ester to be the structural unit derived from the acrylic ester contained in the polymer block (b11) includes at least one selected from the acrylic ester (b11-1) and the acrylic ester (b11 -2) and at least one selected from. In this case, the mass ratio [(b11-1)/(b11-2)] of the structural unit derived from the acrylic ester (b11-1) and the structural unit derived from the acrylic ester (b11-2) is 90. /10 to 10/90, more preferably 80/20 to 20/80, more preferably 70/30 to 30/70, and 60/40 to 40/60 is even more preferred.

When the mass ratio [(b11-1)/(b11-2)] is within the range, the compatibility between the acrylic block copolymer (B) and the styrene block copolymer (A) is enhanced. It is possible to develop more stable adhesion and workability. The mass ratio of the structural unit derived from acrylic acid ester (b11-1) to the structural unit derived from acrylic acid ester (b11-2) can be determined by ¹ H-NMR measurement.

Examples of the combination of the acrylate (b11-1) and the acrylate (b11-2) used in the polymer block (b11) include a combination of n-butyl acrylate and 2-ethylhexyl acrylate. be done.
At this time, the acrylic ester (b11-1) and the acrylic ester (b11-2) to be used have a solubility parameter difference of 0.3 between the acrylic ester (b11-1) and the acrylic ester (b11-2). More preferably, it is up to 2.5 (MPa) ^1/2 .
The solubility parameter is determined by the method described in "POLYMER HANDBOOK Forth Edition", pp. VII 675-714 (Wiley Interscience, 1999) and "Polymer Engineering and Science", 1974, vol. 14, pp. 147-154. can be calculated.
Further, when the acrylic block copolymer (B) contains two or more polymer blocks (b11), the combination and ratio of the acrylic acid esters constituting the polymer blocks (b11) are They may be the same or different.

When the polymer block (b11) is a copolymer containing both a structural unit derived from the acrylic ester (b11-1) and a structural unit derived from the acrylic ester (b11-2), the acrylic ester (b11-1) and acrylic acid ester (b11-2) may be composed of a random copolymer, may be composed of a block copolymer, or may be composed of a gradient copolymer, but usually A random copolymer is preferred. When the acrylic block copolymer (B) contains two or more polymer blocks (b11), the polymer blocks (b11) may have the same or different structures.
Further, the ratio of the total units of the structural units derived from the acrylic acid ester (b11-1) and the acrylic acid ester (b11-2) contained in the polymer block (b11) is 60% by mass in the polymer block (b11). It is preferably at least 80% by mass, more preferably at least 80% by mass, even more preferably at least 90% by mass, and may be substantially 100% by mass.

The glass transition temperature of the polymer block (b11) is preferably −100 to 30° C., more preferably −80 to 10° C., even more preferably −70 to 0° C., and −60 to -10°C is even more preferred. When the glass transition temperature of the polymer block (b11) is within the above range, the hot-melt pressure-sensitive adhesive composition of the present invention containing the acrylic block copolymer (B) has excellent adhesion at room temperature. can.

[Polymer block (b12)]
The polymer block (b12) contains structural units derived from methacrylate. Examples of the methacrylic acid ester include methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate, tert-butyl methacrylate, and methacrylic acid. functional groups such as n-hexyl, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, lauryl methacrylate, tridecyl methacrylate, stearyl methacrylate, isobornyl methacrylate, phenyl methacrylate, and benzyl methacrylate; Methacrylic acid esters that do not have functional groups such as methoxyethyl methacrylate, ethoxyethyl methacrylate, diethylaminoethyl methacrylate, 2-hydroxyethyl methacrylate, 2-aminoethyl methacrylate, glycidyl methacrylate, tetrahydrofurfuryl methacrylate, etc. and acid esters.

Among these, from the viewpoint of improving the heat resistance and durability of the resulting hot-melt pressure-sensitive adhesive composition, methacrylic acid esters having no functional group are preferred, such as methyl methacrylate, ethyl methacrylate, and tert-butyl methacrylate. , cyclohexyl methacrylate, 2-ethylhexyl methacrylate, isobornyl methacrylate, phenyl methacrylate, and benzyl methacrylate are more preferred. Furthermore, methyl methacrylate is more preferable from the viewpoint of making the phase separation between the polymer block (b11) and the polymer block (b12) clearer and improving the mechanical properties of the hot-melt pressure-sensitive adhesive composition.
The polymer block (b12) may be composed of one of these methacrylic acid esters, or may be composed of two or more. In addition, the acrylic block copolymer (B) preferably has two or more polymer blocks (b12) from the viewpoint of enhancing adhesion durability. In that case, those polymer blocks (b12) may be the same or different.

The glass transition temperature of the polymer block (b12) is preferably 80 to 140°C, more preferably 90 to 130°C, even more preferably 100 to 120°C. When the glass transition temperature is within the above range, the polymer block (b12) acts as a physical pseudo cross-linking point for the acrylic block copolymer (B) at the normal operating temperature of the hot-melt pressure-sensitive adhesive composition. The adhesive strength, durability, and heat resistance of the resulting hot-melt pressure-sensitive adhesive composition are further improved.

The polymer block (b11) may contain a structural unit derived from a methacrylic acid ester within a range that does not impair the effects of the present invention, and the polymer block (b12) within a range that does not impair the effects of the present invention. , may contain a structural unit derived from an acrylic acid ester.
Moreover, the polymer block (b11) and the polymer block (b12) may contain structural units derived from monomers other than the (meth)acrylic acid ester, if necessary. Examples of the other monomers include vinyl monomers having a carboxyl group such as (meth)acrylic acid, crotonic acid, maleic acid, fumaric acid; styrene, α-methylstyrene, p-methylstyrene, m- Styrenic monomers such as methylstyrene; conjugated diene monomers such as butadiene and isoprene; olefinic monomers such as ethylene, propylene, isobutene and octene; lactone monomers such as ε-caprolactone and valerolactone (meth)acrylamide, (meth)acrylonitrile, maleic anhydride, vinyl acetate, vinyl chloride, vinylidene chloride and the like.
When these other monomers are used, the amount used is preferably 40% by mass or less, and 20% by mass or less, relative to the total mass of the monomers used in each polymer block. is more preferable, and 10% by mass or less is even more preferable.

The acrylic block copolymer (B) used in the present invention may optionally have other polymer blocks in addition to the polymer block (b11) and the polymer block (b12). . Examples of other polymer blocks include styrene, α-methylstyrene, p-methylstyrene, m-methylstyrene, acrylonitrile, methacrylonitrile, ethylene, propylene, isobutene, butadiene, isoprene, octene, vinyl acetate, and maleic anhydride. Polymer blocks or copolymer blocks containing structural units derived from monomers such as acid, vinyl chloride and vinylidene chloride; polymer blocks composed of polyethylene terephthalate, polylactic acid, polyurethane and polydimethylsiloxane; The polymer block also includes hydrogenated polymer blocks containing structural units derived from conjugated diene compounds such as butadiene and isoprene.

In the acrylic block copolymer (B), the polymer block (b11) is b11, and the polymer block (b11) having a structure different from that of the polymer block (b11) (excluding the polymer block (b12)) is represented by b′11 and the polymer block (b12) by b12, the general formula:
(b12-b11) _n
(b12-b11) _n -b12
b11-(b12-b11) _n
(b12-b11) _n -b'11
(b12-b11) _n -Z
(b11-b12) _n -Z
(Wherein, n is an integer of 1 to 30, Z is the coupling site (coupling site after the coupling agent reacts with the polymer end to form a chemical bond, - is the bond of each polymer block) In addition, when a plurality of b11 and b12 are included in the formula, they may be polymer blocks with the same structure or polymer blocks with different structures.) is preferably represented by
Here, the "different structure" means the monomer units constituting the polymer block, the molecular weight, the molecular weight distribution, the stereoregularity, and in the case of having a plurality of monomer units, the ratio and covalent At least one of the polymerization modes (random, gradient, block) means a different structure.

The value of n is preferably 1-15, more preferably 1-8, even more preferably 1-4. Among the above structures, (b12-b11) _n , (b12-b11) _n -b12, b11-(b12-b11) _n , (b12- b11) A linear block copolymer represented by _n -b'11 is preferable, and a diblock copolymer represented by b12-b11, the polymer block (b12), the polymer block (b11), A triblock copolymer represented by the formula: b12-b11-b'11 having blocks in the order of the polymer block (b'11), and the polymer block (b12), the polymer block (b11), the A triblock copolymer represented by the formula: b12-b11-b12 having blocks in the order of the polymer block (b12) is more preferred, and a triblock copolymer represented by the formula: b12-b11-b12 is even more preferred. .

Further, the acrylic block copolymer (B) in the present invention may be a mixture of a diblock copolymer and a triblock copolymer. A mixture of a block copolymer and a diblock copolymer represented by b12-b11, a mixture of a triblock copolymer represented by b12-b11-b12 and a diblock copolymer represented by b12-b11 A mixture is more preferable, and a mixture of a triblock copolymer represented by b12-b11-b12 and a diblock copolymer represented by b12-b11 is even more preferable.

[Melt viscosity of acrylic block copolymer (B) at 190°C]
The melt viscosity of the acrylic block copolymer (B) at 190°C is preferably more than 100 Pa s and 1,200 Pa s or less, and is lower than the melt viscosity of the styrenic block copolymer (A) at 190°C. . This further improves the compatibility between the styrene block copolymer (A) and the acrylic block copolymer (B).

From the viewpoint of compatibility, the melt viscosity of the acrylic block copolymer (B) at 190° C. is more preferably 160 to 1,150 Pa·s, more preferably 200 to 1,050 Pa·s. It is more preferably 240 to 950 Pa·s, and even more preferably 240 to 950 Pa·s. When the hot-melt pressure-sensitive adhesive composition of the present invention contains two or more acrylic block copolymers (B), the melt viscosity of at least one acrylic block copolymer (B) is within the above range. However, the melt viscosity of the mixture of these acrylic block copolymers (B) (for example, the sum of the product of the weight fraction of each copolymer and the melt viscosity) is preferably within the above range, More preferably, the melt viscosity of the mixture of these acrylic block copolymers (B) is within the above range, and the melt viscosity of all the acrylic block copolymers (B) is within the above range.

[Melt viscosity of acrylic block copolymer (B) at 230°C]
The acrylic block copolymer (B) preferably has a melt viscosity of 20 to 550 Pa·s at 230°C. By including the acrylic block copolymer (B) having a melt viscosity within the above range in the hot-melt pressure-sensitive adhesive composition of the present invention, the substrate made of a highly polar resin such as a PMMA plate is more A hot-melt pressure-sensitive adhesive composition having excellent adhesion and excellent workability can be obtained.
From the viewpoint of improving the processability of the hot-melt pressure-sensitive adhesive composition and the viewpoint of improving compatibility with the styrene block copolymer (A), the melt viscosity of the acrylic block copolymer (B) is more preferably 25 to 450 Pa·s, still more preferably 30 to 350 Pa·s, and even more preferably 35 to 250 Pa·s. When the hot-melt pressure-sensitive adhesive composition of the present invention contains two or more acrylic block copolymers (B), the melt viscosity of the mixture of these copolymers (e.g., the weight fraction of each copolymer and melt viscosity) is preferably within the above range.
In this specification, the melt viscosity of the acrylic block copolymer (B) at 230°C is defined as the melt viscosity measured at a temperature of 230°C and a shear rate of 121.6 (1/sec) according to ISO 11443:1995. means.

[Number average molecular weight of acrylic block copolymer (B)]
The acrylic block copolymer (B) has a number average molecular weight (Mn) of 50,000 to 300,000. By using the acrylic block copolymer (B) having a number average molecular weight within the above range, the obtained hot-melt pressure-sensitive adhesive composition is excellent in adhesiveness and workability. Among them, the Mn is preferably 51,000 to 270,000, more preferably 52,000 to 250,000, from the viewpoint of improving the adhesiveness of the hot-melt pressure-sensitive adhesive composition obtained in the present invention. is more preferred, 53,000 to 230,000 is even more preferred, and 53,000 to 200,000 is even more preferred. When the hot-melt pressure-sensitive adhesive composition of the present invention contains two or more acrylic block copolymers (B), the number average molecular weight of at least one acrylic block copolymer (B) is within the above range. More preferably, the number average molecular weights of all the acrylic block copolymers (B) are within the above range.

The acrylic block copolymer (B) preferably has a molecular weight distribution (Mw/Mn) of 1.00 to 1.40. From the viewpoint of improving the durability of the hot-melt pressure-sensitive adhesive composition, Mw/Mn is more preferably 1.00 to 1.35, more preferably 1.00 to 1.30. It is preferably from 1.00 to 1.25, and most preferably from 1.00 to 1.20. When the hot-melt pressure-sensitive adhesive composition of the present invention contains two or more acrylic block copolymers (B), the Mw/Mn of at least one acrylic block copolymer (B) is within the above range. and more preferably Mw/Mn of all the acrylic block copolymers (B) are within the above range.
The number average molecular weight (Mn) and weight average molecular weight (Mw) of the acrylic block copolymer (B) are values obtained by gel permeation chromatography in terms of standard polystyrene, and molecular weight distribution (Mw/Mn). is a value calculated from the values of Mw and Mn.

[Content of each polymer block]
The content of the polymer block (b11) in the acrylic block copolymer (B) is preferably 70 to 95% by mass. When the content of the polymer block (b11) in the acrylic block copolymer (B) is within the above range, flexibility is imparted to the hot melt pressure-sensitive adhesive composition, It exhibits superior adhesion to substrates made of resin. From the viewpoint of imparting flexibility to the hot-melt pressure-sensitive adhesive composition, the content of the polymer block (b11) in the acrylic block copolymer (B) is more preferably 72 to 93% by mass. More preferably, it is 74 to 91% by mass. When the hot-melt pressure-sensitive adhesive composition of the present invention contains two or more acrylic block copolymers (B), the polymer block (b11) of at least one acrylic block copolymer (B) It is preferably within the above range, and more preferably within the above range for all the polymer blocks (b11) of the acrylic block copolymer (B).

The content of the polymer block (b12) in the acrylic block copolymer (B) is 5-30% by mass. When the content of the polymer block (b12) is within the above range, the processability of the hot-melt pressure-sensitive adhesive composition of the present invention is superior, and the adhesion to PMMA plates is superior. From the viewpoint of workability, the content of the polymer block (b12) is more preferably 7-28% by mass, even more preferably 9-26% by mass. When the hot melt pressure-sensitive adhesive composition of the present invention contains two or more acrylic block copolymers (B), the polymer block (b12) of at least one acrylic block copolymer (B) It is preferably within the above range, and more preferably within the above range for all the polymer blocks (b12) of the acrylic block copolymer (B).
The content of the polymer block (b11) and the polymer block (b12) can be determined by ¹ H-NMR, specifically by the method described in Examples.

[Content of acrylic block copolymer (B)]
The content of the acrylic block copolymer (B) contained in the hot-melt pressure-sensitive adhesive composition of the present invention is preferably 0.5 to 50% by mass, more preferably 1.0 to 45% by mass. is more preferable, and 1.5 to 40% by mass is even more preferable. When the content of the acrylic block copolymer (B) is at least the above lower limit, adhesive residue can be suppressed while maintaining excellent adhesiveness.

[Method for producing acrylic block copolymer (B)]
The method for producing the acrylic block copolymer (B) is not particularly limited as long as the desired polymer can be obtained, and a method according to a known technique can be adopted. In general, as a method for obtaining a block copolymer having a narrow molecular weight distribution, a method of living polymerization of monomers to be structural units can be employed. Examples of such a living polymerization technique include a method of living polymerization using an organic rare earth metal complex as a polymerization initiator (see JP-A-06-93060), an organic alkali metal compound as a polymerization initiator, and an alkali metal or alkaline earth. A method of living anionic polymerization in the presence of a mineral acid salt such as a metal salt (see Japanese Patent Publication No. 05-507737), living anionic polymerization using an organic alkali metal compound as a polymerization initiator in the presence of an organic aluminum compound. method (see JP-A-11-335432), atom transfer radical polymerization (ATRP) (see Macromolecular Chemistry and Physics, 2000, vol. 201, p.1108-1114).

Among the above production methods, the method of performing living anionic polymerization using an organic alkali metal compound as a polymerization initiator in the presence of an organic aluminum compound results in a block copolymer having high transparency, residual monomers, and odor. is suppressed, and when the hot-melt pressure-sensitive adhesive composition is molded, the generation of air bubbles can be suppressed, which is preferable. It is also preferable from the viewpoint that the molecular structure of the structural unit derived from the methacrylic acid ester becomes highly syndiotactic, which has the effect of increasing the heat resistance of the resulting hot-melt pressure-sensitive adhesive composition. In the method of carrying out living anionic polymerization using an organic alkali metal compound as a polymerization initiator in the presence of the above-mentioned organic aluminum compound, it is usually preferable to carry out the polymerization in an organic solvent such as a hydrocarbon. Moreover, it is preferable to add an ether compound, a nitrogen-containing organic compound, or the like to the reaction system, if necessary.

<Tackifying resin (C)>
The hot-melt pressure-sensitive adhesive composition of the present invention contains a tackifying resin (C). In the present invention, the tackiness of the hot-melt pressure-sensitive adhesive composition can be improved by using the tackifier resin (C). The tackifier resin (C) used in the present invention has a softening point of 80 to 160° C., and is composed of rosin resin, terpene resin, phenol resin, terpene phenol resin, hydrogenated petroleum resin, styrene resin, Two or more selected from the group consisting of xylene-based resins, hydrogenated aromatic copolymers and coumarone-indene-based resins. Among these, for example, natural rosin, modified rosin, glycerol ester of natural rosin, glycerol ester of modified rosin, pentaerythritol ester of natural rosin, pentaerythritol ester of modified rosin, hydrogenated rosin, pentaerythritol ester of hydrogenated rosin, etc. Rosin compounds; natural terpene copolymers, natural terpene three-dimensional polymers, aromatic modified terpene resins, hydrogenated derivatives of aromatic modified terpene resins, terpene phenolic resins, hydrogenated derivatives of terpene phenolic resins, terpene resins ( Terpene compounds such as monoterpenes, diterpenes, triterpenes, polypertenes, etc.), hydrogenated terpene resins, etc.; group petroleum hydrocarbon resin (C9 resin), hydrogenated derivative of aromatic petroleum hydrocarbon resin, dicyclopentadiene resin, hydrogenated derivative of dicyclopentadiene resin, C5/C9 copolymer resin, C5/C9 co-polymer It is preferable to use two or more selected from the group consisting of hydrocarbon resins such as hydrogenated polymer resins, cycloaliphatic petroleum hydrocarbon resins, and hydrogenated cycloaliphatic petroleum hydrocarbon resins.

Among these, in the present invention, from the viewpoint of improving compatibility with the styrene block copolymer (A), hydrocarbon resins, and from the viewpoint of compatibility with the acrylic block copolymer (B), , aromatic petroleum hydrocarbon resins (C9 resins), particularly styrene oligomers, are preferably selected, and more preferably two or more of these are used in combination.

The content of the tackifying resin (C) in the hot-melt pressure-sensitive adhesive composition of the present invention is preferably 5 to 40% by mass, more preferably 10 to 38% by mass, and 15 to 35% by mass. % is more preferred. When the content of the tackifying resin (C) in the hot-melt pressure-sensitive adhesive composition is at least the above lower limit, sufficient adhesive strength can be obtained. On the other hand, if the content of the tackifying resin (C) in the hot-melt pressure-sensitive adhesive composition is equal to or less than the upper limit, adhesive residue can be suppressed.

<Softener (D)>
The hot-melt pressure-sensitive adhesive composition of the present invention further contains a softening agent (D). In the present invention, the use of the softening agent (D) improves the fluidity of the hot-melt pressure-sensitive adhesive composition and makes it easier for each component to be uniformly compatible. improves.
In the present invention, one or more selected from the group consisting of liquid acrylic polymers, acrylic oligomers, paraffinic process oils, naphthenic process oils and aromatic process oils is used as the softening agent. The softener (D) is a component other than the styrene block copolymer (A), the acrylic block copolymer (B) and the tackifying resin (C).
Among these, the softener (D) is preferably a liquid acrylic polymer, an acrylic polymer such as an acrylic oligomer, or a paraffin-based process oil.

The content of the softening agent (D) in the hot-melt pressure-sensitive adhesive composition of the present invention is preferably 1 to 30% by mass, more preferably 3 to 25% by mass, and 5 to 20% by mass. is more preferable. When the content of the softening agent (D) in the hot-melt pressure-sensitive adhesive composition is at least the above lower limit, each component of the hot-melt pressure-sensitive adhesive composition can be uniformly mixed. On the other hand, when the content of the softening agent (D) in the hot-melt pressure-sensitive adhesive composition is equal to or less than the upper limit, the effect of the softening agent (D) and the cost are well balanced.

<Optional component>
The hot-melt pressure-sensitive adhesive composition of the present invention may contain optional components other than the above-described components, if necessary, as long as the effects of the present invention are not impaired. Optional components used in the present invention include, for example, antioxidants, inorganic fillers, other thermoplastic polymers (excluding styrene block copolymers (A) and acrylic block copolymers (B)), and lubricants. , light stabilizers, processing aids, coloring agents such as pigments and dyes, flame retardants, antistatic agents, matting agents, silicone oils, antiblocking agents, ultraviolet absorbers, mold release agents, foaming agents, antibacterial agents, antibacterial agents, Optional ingredients such as fungicides and fragrances are included. One of these optional components may be used alone, or two or more thereof may be used in combination.

Examples of the antioxidant include hindered phenol-based, phosphorus-based, lactone-based, and hydroxyl-based antioxidants. Among these, hindered phenol-based antioxidants are preferred. One of the antioxidants may be used alone, or two or more thereof may be used in combination.

The inorganic filler can be contained for the purpose of improving physical properties such as heat resistance and weather resistance of the hot-melt pressure-sensitive adhesive composition of the present invention, adjusting hardness, and improving economic efficiency as a bulking agent. Examples of inorganic fillers include calcium carbonate, talc, magnesium hydroxide, aluminum hydroxide, mica, clay, natural silicic acid, synthetic silicic acid, titanium oxide, carbon black, barium sulfate, glass balloons, and glass fibers. . One of the inorganic fillers may be used alone, or two or more thereof may be used in combination.

When the hot-melt pressure-sensitive adhesive composition of the present invention contains the optional component, the content is preferably 0.5 to 10% by mass, more preferably 1 to 5% by mass, and 1 to 10% by mass. More preferably, it is 3% by mass.

<Melt viscosity (B-type viscosity) of hot-melt adhesive composition>
The melt viscosity at 160° C. of the hot-melt pressure-sensitive adhesive composition is preferably 5,000 to 50,000 mPa s, more preferably 7,000 to 45,000 mPa s, and 8,000 to More preferably, it is 40,000 mPa·s. When the melt viscosity at 160° C. of the hot-melt pressure-sensitive adhesive composition is at least the above lower limit, the hot-melt pressure-sensitive adhesive composition exhibits excellent adhesiveness. On the other hand, when it is equal to or less than the upper limit, it is possible to suppress the adhesive residue of the hot-melt pressure-sensitive adhesive composition.
In this specification, the melt viscosity of the hot-melt pressure-sensitive adhesive composition is a value measured using a Brookfield viscometer, and can be specifically measured by the method described in Examples.

<Method for producing hot-melt pressure-sensitive adhesive composition>
The method for producing the hot-melt pressure-sensitive adhesive composition of the present invention is not particularly limited. It can be produced by mixing at a temperature within the range of 100-250°C. Moreover, after dissolving and mixing each component in an organic solvent, you may manufacture by distilling off this organic solvent. The obtained hot-melt-type adhesive composition can be used by heating and melting, or may be dissolved in a solvent and used as a solution-type adhesive. Examples of solvents include toluene, ethyl acetate, ethylbenzene, methylene chloride, chloroform, tetrahydrofuran, methyl ethyl ketone, dimethyl sulfoxide, toluene-ethanol mixed solvents and the like. Of these, toluene, ethylbenzene, ethyl acetate and methyl ethyl ketone are preferred.

When the hot-melt pressure-sensitive adhesive composition of the present invention is heated and melted for use, it is preferable that the melt viscosity is low from the viewpoint of workability and handleability. On the other hand, from the viewpoint of achieving both adhesive properties and high holding power (creep resistance) of the hot-melt pressure-sensitive adhesive composition, the melt viscosity is preferably high.
The hot-melt pressure-sensitive adhesive composition of the present invention is in the form of a pressure-sensitive adhesive layer made of the hot-melt pressure-sensitive adhesive composition, a laminate (for example, laminated film or laminated sheet) containing the pressure-sensitive adhesive layer, or the like. Suitable for adhesive products.

Examples of the method for forming the adhesive layer include a hot melt coating method, a T-die method, an inflation method, a calendar molding method, and a lamination method when the hot melt adhesive composition of the present invention is heated and melted. and the like to form it into a shape such as a sheet or film. When the melt viscosity of the hot-melt pressure-sensitive adhesive composition of the present invention is high, the hot-melt coating method in which the melt is heated and melted from a T-die onto a support in a non-contact manner is preferred because it is heated and melted at a higher temperature. It is preferable from the viewpoint of layer thickness control, homogeneity, and heat resistance required for the support.
When the hot-melt pressure-sensitive adhesive composition of the present invention is used by dissolving it 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 is applied thereon. , a roll coater, a die coater, a comma coater or the like is used to apply a solution in which the hot-melt adhesive composition of the present invention is dissolved in a solvent, followed by drying to remove the solvent (solution casting method). An adhesive layer can be formed.

A method for removing the solvent by drying is not particularly limited, and a conventionally known method can be used, but it is preferable to divide the drying into a plurality of steps. When drying is performed in multiple 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, and the second and subsequent stages are sufficiently dried. In order to remove the solvent, a method of drying at high temperature is more preferable.

The concentration of the hot-melt pressure-sensitive adhesive composition in the solution is appropriately determined in consideration of the solubility of the composition in the solvent, the viscosity of the resulting solution, etc., but is preferably 5% by mass or more. % or less is more preferable.

<Uses of the hot-melt pressure-sensitive adhesive composition>
The hot-melt pressure-sensitive adhesive composition of the present invention can be used for various purposes. Moreover, the adhesive layer comprising the hot-melt adhesive composition can be used as an adhesive sheet by itself, and the laminate containing the hot-melt adhesive composition can also be applied to various uses. For example, for protection such as surface protection, masking, binding, packaging, office use, labeling, decoration/display, bonding, dicing tape, sealing, anti-corrosion/waterproofing, medical/sanitary use, glass Adhesives and adhesives for scattering prevention, electrical insulation, holding and fixing electronic devices, semiconductor manufacturing, optical display films, adhesive optical films, electromagnetic wave shields, and sealing materials for electrical and electronic parts. tapes, films, sheets, and the like. Specific examples are given below.

Adhesives, adhesive tapes, films, etc. for surface protection can be used for various materials such as metals, plastics, rubbers, and woods. , can be used for surface protection of optical members.
Examples of the automobile parts include painted outer panels, wheels, mirrors, windows, lights, light covers, and the like. 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;・Precision fine-coated face plates for optical applications.

Adhesives, tapes and films for masking are used for masking during manufacturing of printed circuit boards and flexible printed circuit boards; masking during plating and soldering in electronic equipment; manufacturing of vehicles such as automobiles, vehicles and construction. Examples include painting and printing of objects, masking at the end of civil engineering work, and the like.

Binding applications include wire harnesses, electric wires, cables, fibers, pipes, coils, windings, steel materials, ducts, plastic bags, foods, vegetables, and flowers.
Packaging applications include heavy packaging, export packaging, cardboard box sealing, can sealing, and the like.

Office uses include general office use, sealing, repair of books, drafting, memo use, and the like.
Label applications include price, product display, luggage tags, POP, stickers, stripes, nameplates, decorations, advertisements, and the like.

Examples of the label include paper, processed paper (paper subjected to aluminum deposition processing, aluminum lamination processing, varnish processing, resin processing, etc.), paper such as synthetic paper; cellophane, plastic material, cloth, wood and metal A label using a film or the like as a base material can be mentioned. Examples of substrates include woodfree 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, over-laminated film, and the like. be done. Among them, the hot-melt adhesive composition of the present invention is excellent in weather resistance and is less discolored over time, so it can be suitably used for thermal labels using thermal paper or synthetic paper thermal as a base material. can.

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; be done.

A label comprising a laminate containing an adhesive layer comprising the hot-melt adhesive composition of the present invention has little adhesion enhancement during storage at a temperature slightly higher than room temperature (for example, 40° C.), and does not leave adhesive residue after use. Can be peeled off. Moreover, it can be attached to an adherend even at low temperatures (-40 to +10°C) and does not peel off even when stored at low temperatures (-40 to +10°C).

Decorative and display applications include danger display stickers, line tapes, wiring markings, phosphorescent tapes, reflective sheets, and the like.
Examples of adhesive optical film applications include polarizing films, polarizing plates, retardation films, viewing angle widening films, brightness enhancement films, antireflection films, anti-glare films, color filters, light guide plates, diffusion films, prism sheets, and electromagnetic wave shielding films. , Near-infrared absorption film, functional composite optical film, ITO lamination film, impact resistance imparting film, brightness improvement film, visibility improvement film, etc. Forming an adhesive layer on at least a part or all of one side or both sides optical films and the like. Such a pressure-sensitive adhesive optical film includes a film obtained by forming a pressure-sensitive adhesive layer comprising the hot-melt pressure-sensitive adhesive composition of the present invention on a protective film used for surface protection of the optical film. Adhesive optical films are suitably used for various image display devices such as liquid crystal display devices, PDPs, organic EL display devices, electronic papers, game machines, and mobile terminals.

Examples of electrical insulation applications include protective coating or insulation for coils and interlayer insulation for motors, transformers, and the like.
Applications for holding and fixing electronic devices include carrier tapes, packaging, fixing of cathode ray tubes, splicing, rib reinforcement, and the like.

Examples of applications for semiconductor manufacturing include protection of silicon wafers.
Bonding applications include various adhesive fields such as automobiles, trains, electrical equipment, printing plate fixing, construction, nameplate fixing, general household use, and adhesion to rough surfaces, uneven surfaces, and curved surfaces.

Sealing applications include sealing for thermal insulation, vibration isolation, waterproofing, moistureproofing, soundproofing, or dustproofing.
Anticorrosion and waterproofing applications include anticorrosion of gas and water pipes, anticorrosion of large-diameter pipes, anticorrosion of civil engineering buildings, and the like.

For medical and hygiene applications, it is used as an analgesic anti-inflammatory agent (plaster, poultice), ischemic heart disease therapeutic agent, female hormone replacement agent, bronchodilator, cancer pain reliever, smoking cessation aid, cold patch, antipruritic patch, Percutaneous absorption drug applications such as keratin softeners; First-aid bandages (with bactericide), surgical dressings/surgical tapes, bandages, hemostatic bandages, tapes for human excrement treatment attachments (colostomy tapes), suture tapes, antibacterial tapes , fixing taping, self-adhesive bandage, oral mucous membrane adhesive tape, sports tape, hair removal tape, etc. Examples include waterproofing, pest trapping, and the like.
Liquid crystal monitors, solar cells, etc., can be mentioned as sealing material applications for electronic and electric parts.

EXAMPLES The present invention will be described below with reference to Examples, but the present invention is not limited to these Examples. The physical properties of Examples and Comparative Examples were measured or evaluated by the following methods.

[Measurement method and evaluation method]
<Melt viscosity>
The melt viscosities of the styrene block copolymer (A), the styrene block copolymer (A'), the acrylic block copolymer (B) and the acrylic block copolymer (B') are specified in ISO 11443:1995. compliant and measured using a capillograph. The measurement was performed 3 times, and the average value was taken as the melt viscosity.
・ Apparatus: Toyo Seiki Seisakusho Co., Ltd., product name "CAPIROGRAPH 1C"
・Temperature: 190°C or 230°C
・Shear rate: 121.6 (1/sec)
・Capillary die inner diameter: 1.0 mm in diameter
・Capillary die length: 10.0 mm
・Piston diameter: 9.510 mm in diameter
・Furnace diameter: 9.55 mm in diameter

<B type viscosity measurement>
The melt viscosity of the hot-melt pressure-sensitive adhesive composition was measured using a Brookfield viscometer.
・Equipment: manufactured by BLOOKFIELD (DV2T (RV type))
・Number of revolutions: 6 to 50 rpm
・Measurement temperature: 160°C
・Spindle: SC4-29

<Number average molecular weight (Mn), molecular weight distribution (Mw/Mn)>
A number average molecular weight (Mn) and a weight average molecular weight (Mw) were determined by gel permeation chromatography (hereinafter referred to as "GPC") in terms of polystyrene equivalent molecular weight, and the molecular weight distribution (Mw/Mn) was calculated from these values. . Details are as follows.
・ Apparatus: GPC apparatus "HLC-8020" manufactured by Tosoh Corporation
- Separation column: "TSKgel GMHXL", "G4000HXL" and "G5000HXL" manufactured by Tosoh Corporation connected in series - Eluent: Tetrahydrofuran - Eluent flow rate: 1.0 ml/min - Column temperature: 40°C
・Detection method: Differential refractive index (RI)

<Mass of each polymer block in styrene block copolymer (A), styrene block copolymer (A'), acrylic block copolymer (B), and acrylic block copolymer (B') ratio>
styrene block copolymer (A) (block copolymer (P1)), styrene block copolymer (A') (block copolymer (P2)), acrylic block copolymer (B), and The composition ratio of each polymer block and the composition ratio of each polymer block in the acrylic block copolymer (B') were determined by ¹ H-NMR ( ¹ H-nuclear magnetic resonance) measurement under the following measurement conditions. It was determined from the integrated value of the peak assigned to the characteristic group of the mer unit.
〔Measurement condition〕
・Apparatus: Nuclear magnetic resonance apparatus "JNM-LA400" manufactured by JEOL Ltd.
・Heavy solvent: deuterated chloroform

For styrenic block copolymers, block copolymers before hydrogenation (block copolymer (P1), block copolymer (P2), etc.) are dissolved in deuterated chloroform and treated using the apparatus described above. Then, the content of each polymer block was calculated from the ratio of the integrated value of the peak derived from styrene and the integrated value of the peak derived from the conjugated diene.

Regarding the acrylic block copolymer (B) and the acrylic block copolymer (B'), the content of each polymer block was calculated as follows. That is, the signals near 3.6 ppm and 4.0 ppm in the ¹ H-NMR spectrum are hydrogen atoms (—O —CH ₃ ), assigned to the hydrogen atom (—O—CH ₂ —CH ₂ —CH ₂ —CH ₃ ) bonded to the carbon atom adjacent to the oxygen atom contained in the ester group of the structural unit derived from n-butyl acrylate. Then, the molar ratio of each monomer unit is obtained from the ratio of the integrated values of these signals, and this is converted to the mass ratio based on the molecular weight of the monomer unit. From this, the content of each polymer block was calculated.

<1,2-bond and 3,4-bond amount (vinylation degree)>
The 1,2-bond and 3,4-bond amounts (vinylation degree) of the styrene block copolymer (A) and the styrene block copolymer (A') were measured by ¹ H-NMR under the following measurement conditions. ( ¹ H-Nuclear Magnetic Resonance) measurement was carried out and it was determined from the integrated value of the peak attributed to the characteristic group of each monomer unit.
・Apparatus: Nuclear magnetic resonance apparatus "JNM-LA400" manufactured by JEOL Ltd.
・Heavy solvent: deuterated chloroform

[Raw materials used in Examples]
<Production of styrene block copolymer (A) and styrene block copolymer (A')>
(A-1) and (A-2) corresponding to the styrenic block copolymer (A) and (A'-1) corresponding to the styrenic block copolymer (A') are prepared as follows. manufactured.
Monomers corresponding to each block (styrene, isoprene, butadiene ) were sequentially added to obtain a polymerization reaction solution containing a block copolymer (P1) or (P2) composed of a plurality of polymer blocks by anionic polymerization. After stopping the polymerization reaction, palladium carbon as a hydrogenation catalyst was added to the reaction solution containing the block copolymer (P1) or (P2) to carry out a hydrogenation reaction. After stopping the hydrogenation reaction, allowing to cool and releasing the pressure, palladium carbon is removed by filtration, the filtrate is concentrated, and further dried under vacuum to obtain styrenic block copolymers (A-1) and (A-2 ), (A'-1) was obtained. Detailed production conditions can be determined with reference to each synthesis example described in Japanese Patent No. 5936791, for example.
Table 1 summarizes the properties of the styrenic block copolymers (A-1), (A-2) and (A'-1) obtained by the production method.

・Styrenic block copolymer (A-1)
The styrenic block copolymer (A-1) is a hydrogenated triblock copolymer consisting of styrene polymer block/butadiene polymer block/styrene polymer block.

・Styrenic block copolymer (A-2)
The styrene block copolymer (A-2) is a hydrogenated triblock copolymer consisting of styrene polymer block/isoprene polymer block/styrene polymer block.

- Styrene-based block copolymer (A'-1)
The styrene block copolymer (A'-1) is a hydrogenated product of a triblock copolymer consisting of a styrene polymer block/isoprene polymer block/styrene polymer block and a styrene polymer block/isoprene polymer block. It is a mixture with a hydrogenated diblock copolymer.
In the styrene block copolymer (A'-1), the content of the styrene polymer block in the entire mixture is the content of the polymer block (a11), and the Mn, Mw/Mn, melt viscosity of the entire mixture , and the degree of vinylation are the respective values of the styrenic block copolymer (A'-1).

<Acrylic Block Copolymer (B), Acrylic Block Copolymer (B')>
(B-1) to (B-3) corresponding to the acrylic block copolymer (B) and (B'-1) corresponding to the acrylic block copolymer (B') are living anions as follows. Manufactured by polymerization.
In a toluene solvent, the organic alkali metal compound sec -Butyllithium was used as a polymerization initiator, and a predetermined amount of methyl methacrylate was charged according to the charging ratio of each polymer block shown in Table 2. The reaction was initially colored yellow, but became colorless after being stirred at room temperature for 60 minutes. Subsequently, the internal temperature of the polymerization liquid was cooled to -30°C, and a predetermined amount of n-butyl acrylate was continuously charged so as not to exceed -20°C, and after charging, the mixture was stirred at -30°C for 5 minutes. Further, a predetermined amount of methyl methacrylate was added to this and stirred overnight at room temperature to obtain an acrylic block copolymer (B) or an acrylic block copolymer (B') composed of a plurality of polymer blocks. A polymerization reaction solution containing After stopping the polymerization reaction, the aluminum content and lithium content are removed, the polymerization reaction solution is introduced into a devolatilizing twin-screw extruder, the volatile content is removed, and the acrylic block copolymer (B) and the acrylic block A copolymer (B') was obtained. Table 2 summarizes the properties of the acrylic block copolymers (B-1) to (B-3) and (B'-1).

・Acrylic block copolymer (B-1)
As shown in Table 2 below, the acrylic block copolymer (B-1) is a methyl methacrylate polymer block (PMMA)-n-butyl acrylate polymer block (PnBA)-methyl methacrylate polymer block. (PMMA) triblock copolymer.

・Acrylic block copolymer (B-2)
Acrylic block copolymer (B-2) is a triblock copolymer of methyl methacrylate polymer block (PMMA)-n-butyl acrylate polymer block (PnBA)-methyl methacrylate polymer block (PMMA) is.

・Acrylic block copolymer (B-3)
Acrylic block copolymer (B-3) is a triblock copolymer of methyl methacrylate polymer block (PMMA)-n-butyl acrylate polymer block (PnBA)-methyl methacrylate polymer block (PMMA) is.

・Acrylic block copolymer (B'-1)
The acrylic block copolymer (B'-1) is a triblock copolymer of methyl methacrylate polymer block (PMMA)-n-butyl acrylate polymer block (PnBA)-methyl methacrylate polymer block (PMMA). It is a coalescence.

<Tackifying resin>
Table 3 lists the tackifying resins (C) used in Examples and Comparative Examples.

<Softener>
Table 4 lists softening agents (D) used in Examples and Comparative Examples.

<Examples 1 to 10, Comparative Examples 1 to 6>
[Method for producing hot-melt adhesive composition]
The styrenic block copolymer, the acrylic block copolymer, the tackifying resin and the softening agent are melt-kneaded using the following kneader under the following melting temperature and kneading conditions at the blending ratios shown in Table 5, A hot-melt pressure-sensitive adhesive composition was produced.
Kneader: BENCH KNEADER PBV-0.3K (Irie Shokai Co., Ltd.)
Melting temperature: 180°C
Rotation speed: 40rpm

Then, the resulting hot-melt adhesive composition was applied to a polyethylene terephthalate (PET) film (Ester Film A3100, manufactured by Toyobo Co., Ltd., thickness 50 μm) on the non-releasing surface thereof so as to have a thickness of 25 μm. was used to perform hot-melt coating at the following melting temperature to obtain an adhesive roll film composed of a PET film layer and an adhesive layer.
Coating machine: Hot melt lab coater KMD-HML10 (Kubo Design Co., Ltd.)
Melting temperature: 160°C
A sample having a width of 25 mm and a length of 150 mm was cut from the obtained adhesive roll film to form an adhesive tape, and the adhesive properties were evaluated by the following methods.

<Test method for adhesive strength>
The adhesive tape is attached to the adherend (acrylic plate [PMMA], stainless steel plate [SUS304], polyethylene plate [HDPE plate], hard polyvinyl chloride plate [hard PVC plate]), and then adjusted for 24 hours under conditions of 23°C and 50% RH and for 168 hours under conditions of 60°C and 50% RH. Then, in accordance with JIS Z0237: 2009, the force applied when peeling off the laminated film is measured by the following tensile tester under the following tensile conditions (tensile speed, peeling angle) under the following measurement environment. An average value of 5 pieces was obtained.
Tensile tester: desktop tensile tester (AGS-X: manufactured by Shimadzu Corporation)
Tensile speed: 300mm/min
Peeling angle: 180°
Measurement environment: 23°C x 50RH

Table 5 shows the results. The rate of change in adhesive strength in Table 5 means "adhesive strength after storage at 60°C for 168 hours"/"adhesive strength after storage at 23°C and 50% RH for 24 hours".

<Adhesive residue>
After the adhesive tape was peeled off, the traces of sticking on the adherend were visually observed, and the contamination of the adherend was evaluated according to the following criteria.
E (Excellent): No trace of adhesive tape was observed on the surface of the adherend.
G (Good): Slight traces of the adhesive tape applied to the adherend surface, but no practical problem.
P (Poor): Strong traces of adhesive tape applied to the adherend surface.

As is clear from the results of Examples and Comparative Examples, the hot-melt pressure-sensitive adhesive composition of the present invention has excellent adhesive strength to various adherends, and adheres when the hot-melt pressure-sensitive adhesive composition is peeled off. Adhesive residue on the body can be suppressed.

Claims (4)

It contains a styrene block copolymer (A), an acrylic block copolymer (B), a tackifying resin (C) and a softening agent (D), and is characterized by satisfying the following conditions (1) to (6). A hot-melt pressure-sensitive adhesive composition.
<Condition (1)>
The melt viscosity (P A ) of the styrenic block copolymer (A) at 190° C. and the melt viscosity (P _B ) of the acrylic block copolymer ( _B ) at 190° C. have a relationship of P _A <P _B. meet.
<Condition (2)>
The mass ratio [(A)/(B)] of the content of the styrene block copolymer (A) to the acrylic block copolymer (B) is 10/90 to 95/5.
<Condition (3)>
The styrenic block copolymer (A) comprises one or more polymer blocks (a11) containing a structural unit derived from a styrene compound and a polymer block (a12) containing a structural unit derived from a conjugated diene compound. It is a hydrogenated product of the block copolymer (P1) having one or more, and the melt viscosity (P _A ) measured at a temperature of 190° C. and a shear rate of 121.6 (1/sec) in accordance with ISO 11443:1995 is 100 Pa·s or more and less than 600 Pa·s.
<Condition (4)>
The acrylic block copolymer (B) comprises one or more polymer blocks (b11) containing a structural unit derived from an acrylic acid ester and a polymer block (b12) containing a structural unit derived from a methacrylic acid ester. having one or more, a number average molecular weight (Mn) of 50,000 to 300,000, and a content of the polymer block (b12) in the acrylic block copolymer (B) of 5 to 30% by mass; is.
<Condition (5)>
The tackifying resin (C) is a tackifying resin having a softening point of 80 to 160° C., and is a rosin-based resin, a terpene-based resin, a phenol-based resin, a terpene-phenol-based resin, a hydrogenated petroleum-based resin, or a styrene-based resin. , xylene-based resins, hydrogenated aromatic copolymers and coumarone-indene-based resins.
<Condition (6)>
The softener (D) is one or more selected from the group consisting of liquid acrylic polymers, acrylic oligomers, paraffinic process oils, naphthenic process oils and aromatic process oils. The hot-melt pressure-sensitive adhesive composition according to claim 1, wherein the acrylic block copolymer (B) has a melt viscosity (P _B ) of more than 100 Pa·s and 1,200 Pa·s or less at 190°C. 3. The hot-melt pressure-sensitive adhesive composition according to claim 1, wherein the content of said styrenic block copolymer (A) contained in said hot-melt pressure-sensitive adhesive composition is 3 to 70% by mass. The content of the acrylic block copolymer (B) contained in the hot melt adhesive composition is 0.5 to 50% by mass, the hot according to any one of claims 1 to 3 A melt-type adhesive composition.