JP2018150430A - Asphalt composition and modified asphalt mixture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an asphalt composition which can simultaneously satisfy high softening property, low melt viscosity property, thermal resistant stability and aggregate peeling resistant performance, in a good balance.SOLUTION: An asphalt composition contains a block copolymer (A), a crosslinking agent (B) and asphalt (C), where a ratio of the block copolymer (A) is 0.5 pts.mass or more and 20 pts.mass or less with respect to 100 pts.mass of the asphalt (C), a ratio of the crosslinking agent (B) is 0.03 pts.mass or more and 3 pts.mass or less with respect to 100 pts.mass of the asphalt (C), the block copolymer (A) contains a polymer block (a) containing a vinyl aromatic monomer unit as a main component and a polymer block (b) containing a conjugated diene monomer unit and a vinyl aromatic monomer unit as main components, and a hydrogenation rate of a double bond in the conjugated diene monomer unit is 10 mol% or more and 85 mol% or less.SELECTED DRAWING: None

Description

  The present invention relates to asphalt compositions and modified asphalt mixtures.

  Block copolymers are widely used in asphalt compositions. In the technical field of asphalt composition, in order to add performance according to the use of asphalt composition such as road pavement, sound insulation sheet, asphalt roofing, etc., asphalt in which various block copolymers are added to the asphalt composition as a modifier Compositions are widely used. As such a block copolymer as a modifier, for example, a block copolymer containing a conjugated diene monomer unit and a vinyl aromatic monomer unit is used.

  For example, Patent Documents 1 to 4 describe asphalt compositions containing a hydrogenated block copolymer obtained by copolymerizing a conjugated diene monomer and a vinyl aromatic monomer.

JP 2005-126485 A US Patent Application Publication No. 2003/0149140 JP 2012-246378 A Japanese Patent No. 5059595

  The asphalt composition is required to simultaneously satisfy a high softening property, a low melt viscosity, a heat stability and an anti-aggregate peeling performance when mixed with an aggregate to form a modified asphalt mixture. Moreover, when manufacturing a pavement material using a modified asphalt mixture, it is calculated | required that a modified asphalt mixture balances the outstanding workability and fluid resistance. Furthermore, the modified asphalt mixture is required to be able to impart excellent excavation resistance during paving. However, the asphalt compositions described in Patent Documents 1 to 4 cannot sufficiently meet the above-described requirements.

  Therefore, the present invention has been made in view of the above-described problems of the prior art, and asphalt capable of simultaneously satisfying a high softening property, a low melt viscosity property, a heat resistance stability, and an anti-aggregation performance in a balanced manner. An object is to provide a composition.

  As a result of intensive studies to solve the above problems, the present inventors have found that a composition comprising a block copolymer having a specific structure, asphalt, and a crosslinking agent at a predetermined ratio solves the above problems. The present invention has been completed by finding out what can be done.

That is, the present invention is as follows.
[1]
An asphalt composition containing a block copolymer (A), a crosslinking agent (B), and an asphalt (C),
The ratio of the block copolymer (A) is 0.5 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of asphalt (C).
The ratio of the crosslinking agent (B) is 0.03 parts by mass or more and 3 parts by mass or less with respect to 100 parts by mass of asphalt (C).
The block copolymer (A) is a polymer block (a) mainly composed of a vinyl aromatic monomer unit, and a polymer block mainly composed of a conjugated diene monomer unit and a vinyl aromatic monomer unit. And (b) an asphalt composition having a hydrogenation rate of a double bond in the conjugated diene monomer unit of 10 mol% or more and 85 mol% or less.
[2]
The block copolymer (A) has a structure (I) represented by the following formula (1), a structure (II) represented by the following formula (2), and a structure represented by the following formula (3) ( The asphalt composition according to item [1] above, which contains at least one structure selected from the group consisting of III), wherein the double bond in the conjugated diene monomer unit in each structure is partially hydrogenated. .

(P) _n -q (1)
(In the formula, p represents ab or ba, q represents a or b, n represents an integer of 1 or more, a represents the polymer block (a), b Represents the polymer block (b), provided that when q is a, p is a-b, when q is b, p is b-a, and q is present It may not be present, and when a plurality of a or b are included, the plurality of a or b may be the same as or different from each other.

(Y) _m -X (2)
(In the formula, X represents a residue of a coupling agent, Y represents (p) _n -q or q- (p) _n , m represents an integer of 1 or more, p, q, and n is the same as the formula (1).)

(Y) _k- Z (3)
(In the formula, Z represents a residue of a polymerization initiator or a stopper, Y represents (p) _n -q or q- (p) _n , k represents an integer of 1 or more, p, q and n are the same as those in the formula (1).)
[3]
The asphalt composition according to item [2], wherein the block copolymer (A) contains the structure (I) represented by the formula (1) and the structure (II) represented by the formula (2).
[4]
The ratio of the structure (I) represented by the formula (1) and the structure (II) represented by the formula (2) is the former / the latter (mass ratio) = 5/95 or more and 70/30 or less. The asphalt composition according to [3] above.
[5]
The asphalt composition according to any one of [1] to [4], wherein the block copolymer (A) contains a functional group.
[6]
A modified asphalt mixture comprising the asphalt composition according to any one of [1] to [5] above and an aggregate.
[7]
The modified asphalt mixture according to the above item [6], which is used for paving.

  The asphalt composition of the present invention can simultaneously satisfy a high softening property, a low melt viscosity, a heat stability, and an anti-aggregate performance in a balanced manner.

  Hereinafter, a mode for carrying out the present invention (hereinafter referred to as “the present embodiment”) will be described in detail. The present invention is not limited to the following embodiments, and various modifications can be made within the scope of the invention.

As used herein, “monomer unit” refers to a structural unit that constitutes a block copolymer, and “monomer” refers to a material that constitutes a block copolymer. Further, “mainly” as used in the present specification means that the content of a predetermined monomer unit in the polymer block (a) is 70% by mass or more. The polymer block (a) mainly composed of vinyl aromatic monomer units may have a vinyl aromatic monomer unit content of 70% by mass or more, preferably 80% by mass, more preferably 90% by mass. % Of the polymer block (b) mainly comprising a conjugated diene monomer unit and a vinyl aromatic monomer unit, the conjugated diene monomer unit and the vinyl aromatic monomer The total content of the body units may be 70% by mass or more, preferably 80% by mass, more preferably 90% by mass or more, and particularly 100% by mass. Further, the “conjugated diene monomer” as used herein includes not only a conjugated diene monomer that is not hydrogenated but also a conjugated diene monomer that is hydrogenated.
In addition, the term “highly softening” as used in the present specification refers to the property that the asphalt composition has a high softening point, and “low melt viscosity” refers to the property that the asphalt composition has a low melt viscosity. “Stability” means, for example, a property having high heat resistance when an asphalt composition is stored for a long period of time (for example, about one week) under a high temperature condition. Refers to the ability of the aggregate not to exfoliate when the asphalt composition is mixed with the aggregate to form a modified asphalt mixture. “Compatibility” refers to the compatibility between the asphalt and the block copolymer. Say.

<Asphalt composition>
The asphalt composition of this embodiment is an asphalt composition containing a block copolymer (A), a crosslinking agent (B), and an asphalt (C), and the ratio of the block copolymer (A) Is 0.5 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of asphalt (C), and the ratio of the crosslinking agent (B) is 0.03 parts by mass with respect to 100 parts by mass of asphalt (C). The block copolymer (A) is a polymer block (a) mainly composed of a vinyl aromatic monomer unit, a conjugated diene monomer unit, and a vinyl aromatic monomer. And a polymer block (b) mainly composed of units, and the hydrogenation rate of double bonds in the conjugated diene monomer unit is 10 mol% or more and 85 mol% or less. The asphalt composition of this embodiment can satisfy | fill high softening property, low melt viscosity, heat-resistant stability, and aggregate peeling-proof performance simultaneously with sufficient balance by having said characteristic. In addition, the asphalt composition of the present embodiment tends to achieve both excellent workability and flow resistance when producing a paving material. Furthermore, the asphalt composition of the present embodiment tends to provide excellent excavation resistance during paving.

<Block copolymer (A)>
The block copolymer of the present embodiment includes a polymer block (a) mainly composed of vinyl aromatic monomer units, and a polymer block mainly composed of conjugated diene monomer units and vinyl aromatic monomer units. (B).

(Polymer block (a))
In the present embodiment, the polymer block (a) is a block mainly composed of a vinyl aromatic monomer. The vinyl aromatic monomer unit is not particularly limited. For example, styrene, α-methylstyrene, p-methylstyrene, divinylbenzene, 1,1-diphenylethylene, N, N-dimethyl-p-aminoethylstyrene. And vinyl aromatic monomer units derived from N, N-diethyl-p-aminoethylstyrene. Among these, a vinyl aromatic monomer unit derived from styrene is preferable from the viewpoint of economy. A vinyl aromatic monomer unit can be used individually by 1 type or in combination of 2 or more types.

  The content of the polymer block (a) is 5% by mass or more and 40% by mass or less with respect to the whole block copolymer, and 5% by mass or more is from the viewpoint of further improving the tensile recovery property and the high softening property. It is preferably 8% by mass or more, more preferably 12% by mass or more, and particularly preferably 16% by mass or more. On the other hand, from the viewpoint of further improving the low melt viscosity, it is preferably 40% by mass or less, more preferably 35% by mass or less, further preferably 30% by mass or less, and particularly preferably 25% by mass or less.

The content of the polymer block (a) can be determined by, for example, a method of oxidatively decomposing a polymer with tertiary butyl hydroperoxide using osmium tetroxide as a catalyst (IM KOLTHOFF, et.al, J. Polym. Sci. 1, p.429 (method described in 1946)), the mass of the vinyl aromatic polymer block component (however, the vinyl aromatic polymer block component having an average degree of polymerization of about 30 or less is excluded). And can be obtained by the following formula (1a).

Content (% by mass) of polymer block (a)
= (Mass of vinyl aromatic polymer block component / mass of block copolymer (A))
× 100 (1a)

  In addition, when the block copolymer is hydrogenated (hydrogenated), the content of the polymer block (a) with respect to the whole block copolymer is the block copolymer weight of the polymer block (a) before hydrogenation. In the present embodiment, the content of the polymer block (a) in the case where the block copolymer is hydrogenated is the content of the polymer block (a) before hydrogenation because the content is almost equal to the content of the whole coalescence. It may be obtained as an amount.

(Polymer block (b))
The polymer block (b) of this embodiment is mainly composed of a conjugated diene monomer unit and a vinyl aromatic monomer unit. The conjugated diene monomer unit is not particularly limited. For example, 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 1,3 -Conjugated diene monomer units derived from pentadiene, 2-methyl-1,3-pentadiene, 1,3-hexadiene. Among these, from the viewpoint of excellent mechanical strength and low cost, conjugated diene monomer units derived from 1,3-butadiene and isoprene are preferred, and conjugated diene monomer units derived from 1,3-butadiene are preferred. More preferred. A conjugated diene monomer unit can be used individually by 1 type or in combination of 2 or more types.

  The conjugated diene monomer unit of the present embodiment includes, for example, a conjugated diene monomer unit derived from 1,2-bond and / or 3,4-bond and a conjugated diene monomer derived from 1,4-bond. It consists of body units.

  As used herein, “a conjugated diene monomer unit derived from a 1,2-bond and / or 3,4-bond” means that a conjugated diene compound is a 1,2-bond and / or a 3,4-bond. This is a unit per conjugated diene compound produced as a result of polymerization. The “conjugated diene monomer unit derived from 1,4-bond” is a unit per conjugated diene compound produced as a result of polymerization of a conjugated diene compound with 1,4-bond.

  The content of conjugated diene monomer units derived from 1,2-bonds and / or 3,4-bonds relative to the total content of conjugated diene monomer units in the block copolymer (hereinafter referred to as “vinyl bond amount”). Is preferably 10% by weight or more, more preferably 13% by weight or more, and more preferably 17% by weight or more from the viewpoint that the asphalt composition has high penetration and excellent compatibility with asphalt. Preferably, 24% by weight or more is most preferable. On the other hand, from the viewpoint of further improving heat stability and compatibility, it is preferably 45% by weight or less, more preferably 40% by weight or less, still more preferably 36% by weight or less, and particularly preferably 32% by weight or less. The vinyl bond amount can be measured by NMR, specifically by the method described in the examples described later.

  The polymer block (b) of this embodiment further contains a vinyl aromatic monomer unit. As a vinyl aromatic monomer unit which comprises a polymer block (b), the vinyl aromatic monomer unit illustrated as a vinyl aromatic monomer unit which comprises a polymer block (a) can be illustrated.

  In the polymer block (b) of this embodiment, there may be a distribution of vinyl bond amount. The lower limit of the difference in the amount of vinyl bonds in the polymer block (b) (hereinafter also referred to as “Δ vinyl bond amount”) is 5 mol% from the viewpoint of excellent low-temperature elongation of asphalt compositions and modified asphalt mixtures. The above is preferable, 8 mol% or more is more preferable, 15 mol% or more is further preferable, and 20 mol% or more is particularly preferable. Further, the upper limit value of the Δ vinyl bond amount is preferably 30 mol% or less, more preferably 25 mol% or less, further preferably 20 mol% or less, and more preferably 17 mol% from the viewpoint of excellent compatibility of the asphalt composition and the modified asphalt mixture. The following are particularly preferred:

  In the present embodiment, the polymer block (b) is a block containing a vinyl aromatic monomer and a conjugated diene monomer, and the content of the vinyl aromatic monomer unit in the polymer block (b). Is preferably 5% by mass or more and 95% by mass or less based on the entire polymer block (b). In the present embodiment, the content of the vinyl aromatic monomer unit relative to the entire polymer block (b) is preferably 5% by mass or more, more preferably 20% by mass or more, from the viewpoint of further improving the high softening property. More preferably, the content of the vinyl aromatic monomer unit relative to the entire polymer block (b) is preferably 95% by mass or less, more preferably 50% by mass, from the viewpoint of further improving the heat resistance stability. The following is more preferable, 35% by mass or less is more preferable, and 30% by mass or less is particularly preferable.

The content (RS) of the vinyl aromatic monomer unit relative to the entire polymer block (b) is, for example, from the content (TS) of the vinyl aromatic monomer unit relative to the entire block copolymer. It can be obtained by dividing the content (BS) of the block (a).

RS (%) = (TS−BS) / (100−BS) × 100

  The polymer block (b) is preferably a random block. Here, “random” means a state in which the number of continuous vinyl aromatic monomer units in the polymer block (b) is 10 or less.

  Although the lower limit of the content of the short chain vinyl aromatic monomer polymerization portion in the polymer block (b) in this embodiment is not particularly limited, the vinyl aromatic monomer unit in the polymer block (b) Preferably it is 50 mass% or more with respect to 100 mass% of total content, More preferably, it is 70 mass% or more, More preferably, it is 80 mass% or more, Most preferably, it is 90 mass% or more. Moreover, the upper limit of the content of the short chain vinyl aromatic monomer polymerization portion in the polymer block (b) is not particularly limited, but the total content of vinyl aromatic monomer units in the polymer block (b) is not limited. Preferably it is 100 mass% or less with respect to 100 mass% of quantity, More preferably, it is 99 mass% or less. When the content of the polymer moiety of the short chain vinyl aromatic monomer in the polymer block (b) is within the above range, the compatibility, elongation and heat resistance stability of the block copolymer and asphalt are further improved. There is a tendency to further improve.

  Here, the “short chain vinyl aromatic monomer polymerization portion” is a component composed of 2 to 6 vinyl aromatic monomer units in the polymer block (b). And content of the short chain vinyl aromatic monomer polymerization part made the vinyl aromatic monomer unit total content in a polymer block (b) 100 mass%, and connected 2-6 pieces in it It is calculated | required as content of a vinyl aromatic monomer unit.

  Further, the content of the two connected vinyl aromatic monomer units is preferably 10% by mass or more and 45% with respect to 100% by mass of the total content of vinyl aromatic monomer units in the polymer block (b). It is not more than mass%, more preferably not less than 13 mass% and not more than 42 mass%, and still more preferably not less than 19 mass% and not more than 36 mass%. When the content of the two linked vinyl aromatic monomer units is within the above range, the compatibility, elongation, and heat stability of the block copolymer and asphalt tend to be further improved.

  Further, the content of the three connected vinyl aromatic monomer units is preferably 45% by mass or more and 80% by mass with respect to 100% by mass of the total vinyl aromatic monomer unit content in the polymer block (b). It is not more than mass%, more preferably not less than 45 mass% and not more than 75 mass%, and still more preferably not less than 45 mass% and not more than 65 mass%. When the content of the three linked vinyl aromatic monomer units is within the above range, the compatibility, elongation, and heat stability of the block copolymer and asphalt tend to be further improved.

In the polymer block (b) including the conjugated diene monomer unit and the vinyl aromatic monomer unit, the first region to the sixth region are set to have the same mass in order from the polymerization initiation terminal side. When the vinyl content (vinyl bond amount) before hydrogenation in the 6 regions is V _{1 to} V ₆ , the distribution of the vinyl content (vinyl bond amount) is not particularly limited and may be constant or tapered. Alternatively, it may be distributed in a convex shape or a concave shape. By adding a polar compound in the middle of the polymerization or controlling the polymerization temperature, the vinyl distribution can be tapered, convex, or concave.

The tapered distribution means a distribution satisfying V ₆ > V ₅ > V ₄ > V ₃ > V ₂ > V ₁ , or V ₆ <V ₅ <V ₄ <V ₃ <V ₂ <V ₁ . The convex distribution, V ₆ and V ₁ is smaller than V ₅ and V _2, V ₅ and V ₂ refers to a smaller distribution than V ₄ and V _3. The concave profile, greater than V ₆ and V ₁ is V ₅ and V _2, V ₅ and V ₂ means a larger distribution than V ₄ and V _3.

(Hydrogenation rate of block copolymer)
In this embodiment, the hydrogenation rate of the double bond in the conjugated diene monomer unit is 10 mol% or more and 85 mol% or less. “Hydrogenation rate” here refers to the hydrogenation rate (mol%) which is the content of hydrogenated conjugated diene monomer units in the total content of conjugated diene monomer units. It is also referred to as the “additional rate”.
The hydrogenation rate of the block copolymer is 10 mol% or more, preferably 30 mol% or more, more preferably 50 mol% or more, and particularly preferably 60 mol% or more from the viewpoint of excellent heat stability.
On the other hand, the hydrogenation rate of the block copolymer is 85 mol% or less, preferably 70 mol% or less, more preferably 50 mol% or less, and particularly preferably 30 mol% or less, from the viewpoint of excellent low melt viscosity.
Moreover, when the hydrogenation rate of the block copolymer is 10 mol% or more and 85 mol% or less, the compatibility with asphalt tends to be excellent. The hydrogenation rate of the block copolymer is preferably 30 mol% or more and 80 mol% or less, more preferably 40 mol% or more and 75 mol% or less, and further preferably 50 mol% or more and 70 mol% or less from the viewpoint of further improving the compatibility.
Further, when the hydrogenation rate of the block copolymer is 85 mol% or less, the reactivity of the block copolymer and the crosslinking agent tends to be excellent. The hydrogenation rate of the block copolymer is more preferably 80 mol% or less, more preferably 70 mol% or less, and even more preferably 60 mol% or less, from the viewpoint of further improving the reaction rate with the crosslinking agent.
Further, if the hydrogenation rate of the block copolymer is 10 mol% or more and 85 mol% or less, the compatibility with asphalt is excellent, and the adhesion between the asphalt composition and the aggregate is improved. Aggregate peeling performance is obtained. The hydrogenation rate of the block copolymer is preferably 15 mol% or more and 80 mol% or less, more preferably 30 mol% or more and 75 mol% or less, from the viewpoint of further improving the anti-aggregation performance.
Moreover, by making it into the range of a suitable hydrogenation rate, it is excellent in the balance of the heat resistance stability and the reactivity with a crosslinking agent, and predetermined | prescribed performance can be obtained. In the present embodiment, the hydrogenation rate can be determined by the method described in the examples described later.

(Content of vinyl aromatic monomer unit in block copolymer)
In the present embodiment, the content of the vinyl aromatic monomer unit is preferably 5% by mass or more and 60% by mass or less with respect to the entire block copolymer, from the viewpoint of further improving the high softening property. 5 mass% or more is preferable, 15 mass% or more is more preferable, 25 mass% or more is further more preferable, and 35 mass% or more is especially preferable. On the other hand, the content of the vinyl aromatic monomer unit is preferably 60% by mass or less, more preferably 50% by mass or less, from the viewpoint that the asphalt composition has an even higher penetration and low melt viscosity. More preferably, it is less than or equal to 30% by weight, particularly preferably less than or equal to 30% by weight. In addition, content of a vinyl aromatic monomer unit can be measured by the method as described in the Example mentioned later.

  The content of vinyl aromatic monomer units in the entire block copolymer when the block copolymer is hydrogenated is the content of vinyl aromatic monomer units in the entire block copolymer before hydrogenation. Therefore, the content of the vinyl aromatic monomer unit when the block copolymer is hydrogenated may be obtained as the content of the vinyl aromatic monomer unit before hydrogenation.

  The distribution of vinyl aromatic monomer units in the polymer block (a) mainly composed of vinyl aromatic monomer units and in the polymer block (b) when containing vinyl aromatic monomer units is as follows: However, it is not particularly limited, and it may be distributed uniformly, or may be distributed in a tapered shape, a staircase shape, a convex shape, or a concave shape. Crystal parts may be present in the polymer block (a) and / or (b). In the polymer block (a) mainly composed of vinyl aromatic monomer units, a plurality of segments having different contents of vinyl aromatic monomer units may coexist.

  The block copolymer of the present embodiment preferably contains a functional group from the viewpoint of excellent interaction with asphalt and / or aggregate. The functional group is not particularly limited, but is, for example, at least one functional group selected from the group consisting of a hydroxyl group, an acid anhydride group, an epoxy group, an amino group, an amide group, a silanol group, and an alkoxysilane group. . In the present embodiment, these functional groups are preferably added to the block copolymer, and the addition method is not particularly limited. For example, these monomers may be added to the monomers constituting the block copolymer. A method using a monomer having a functional group, a method of bonding a monomer unit constituting a block copolymer, and a residue of a polymerization initiator, a coupling agent, or a terminating agent having these functional groups, etc. Is mentioned.

(Block copolymer structure)
The block copolymer of the present embodiment is represented by, for example, the structure (I) represented by the following formula (1), the structure (II) represented by the following formula (2), and the following formula (3). It contains at least one structure selected from the group consisting of structure (III), and the double bond in the conjugated diene monomer unit in each structure is partially hydrogenated.

(P) _n -q (1)
(In the formula, p represents ab or ba, q represents a or b, n represents an integer of 1 or more, a represents the polymer block (a), b Represents the polymer block (b), provided that when q is a, p is a-b, when q is b, p is b-a, and q is present It may not be present, and when a plurality of a or b are included, the plurality of a or b may be the same as or different from each other.

(Y) _m -X (2)
(In the formula, X represents a residue of a coupling agent, Y represents (p) _n -q or q- (p) _n , m represents an integer of 1 or more, p, q, and n is the same as the formula (1).)

(Y) _k- Z (3)
(In the formula, Z represents a residue of a polymerization initiator or a stopper, Y represents (p) _n -q or q- (p) _n , k represents an integer of 1 or more, p, q and n are the same as those in the formula (1).)

Specific examples of the structure (I) represented by the formula (1) include the structures represented by the following (Ia), (Ib), and (Ic).
(Ab) _n (Ia)
(Ab) _n- a (Ib)
(Ba) _n -b (Ic)
(In the formula, a, b and n are the same as those in the formula (1).)

  In the above formulas (1), (Ia), (Ib), and (Ic), n is preferably 1 to 5, more preferably, from the viewpoint of further excellent low melt viscosity. Is 1 to 3, more preferably 1 or 2, and particularly 1.

  In the present embodiment, from the viewpoint of excellent low melt viscosity, the block copolymer is one polymer block (a) mainly composed of vinyl aromatic monomer units and at least one conjugated diene monomer. It is preferable to include a block copolymer containing one polymer block (b) (a structure represented by the formula (1) and n is 1).

  In the present embodiment, the content of the structure represented by the formula (1) where n is 1 is preferably 5% by mass or more from the viewpoint of further improving the low melt viscosity with respect to the entire block copolymer. 10 mass% or more is more preferable, 14 mass% or more is further more preferable, and 18 mass% or more is especially preferable. On the other hand, the content is preferably 90% by mass or less, more preferably 75% by mass or less, still more preferably 60% by mass or less, and particularly preferably 40% by mass or less, from the viewpoint of further improving the elongation and high softening properties. .

  The block copolymer of this embodiment is represented by the structure (I) represented by the above formula (1) and the above formula (2) from the viewpoint that the compatibility and the anti-aggregation performance of the aggregate are further excellent. Preferably it contains the structure (II). When the block copolymer contains the structure (II) represented by the formula (2), when manufacturing a paving material, it is possible to achieve both excellent workability and fluid resistance, At this time, there is a tendency that even better excavation resistance can be imparted.

Specific structures of the structure (II) represented by the formula (2) include the following (II-a), (II-b), (II-c), (II-d), (II-e) ) And (II-f).
[(Ab) _n ] _m -X (II-a)
[(B-a) _n ] _m- X (II-b)
[A- (ba) _n ] _m- X (II-c)
[(Ab) _n -a] _m -X (II-d)
[B- (ab) _n ] _m- X (II-e)
[(Ba) _n -b] _m -X (II-f)

  As a coupling agent, the coupling agent illustrated by the term of the manufacturing method of the block copolymer mentioned later is mentioned.

  In the above formulas (2) and (II-a) to (II-f), m is preferably 3 or more, 6 or less, more preferably 3 or more and 5 or less, and 3 or 4. Further preferred. By including the structure (II) in which m is in the above range, the block copolymer is further excellent in high softening properties, and further imparts better workability and fluid resistance when used as an asphalt mixture. It tends to be possible. In this specification, a structure represented by the above formula (2) and m is 3 or more is referred to as a “radial structure”.

  The copolymer block of this embodiment may be represented by the above formula (2) (or (II-a) to (II-f)), and may contain a plurality of structures in which m is different.

A typical combination of the structure (I) represented by the formula (1) of the present embodiment and the structure (II) represented by the formula (2) is not particularly limited. Combinations are listed.
(1) (ab) _n and [(ab) _n ] _m -X
(2) (ab) _n and [(ba) _n ] _m -X
(3) (ab) _n -a and [(ab) _n -a] _m -X

  The ratio of the structure (I) represented by the above formula (1) and the structure (II) represented by the above formula (2) is not particularly limited, but from the viewpoint of further improving the high softening property and the low melt viscosity. The former / the latter (mass ratio) is preferably 5/95 or more and 70/30 or less, more preferably 8/92 or more and 65/35 or less, and 15/85 or more and 55/45 or less. Further preferred.

  In addition, the boundary and the endmost part of each polymer block (a) and (b) do not necessarily need to be clearly distinguished.

In this embodiment, it is preferable that a block copolymer contains the said radial structure also from a viewpoint which low melt viscosity is further excellent. Although it does not specifically limit as a radial structure, For example, [a- (ba) _{n] m-} X (m> = 3), [(ab) _n ] _m- X (m> = 3), and [( a-b) _n- a] _m- X (m> = 3).

Typical radial structures include [(ab) _n ] _m -X and [(ab) _n -a] _m -X (wherein the above formula, m represents an integer of 3 to 6, n represents an integer of 1 to 4, and more preferably, m represents an integer of 3 to 4.) and at least one structure selected from the group consisting of preferable.

Specific structures of the structure (III) represented by the above formula (3) include the following (III-a), (III-b), (III-c), (III-d), (III-e) ) And (III-f).
[(Ab) _n ] _k -Z (III-a)
[(B-a) _n ] _k- Z (III-b)
[A- (b-a) _n ] _k- Z (III-c)
[(Ab) _n -a] _k -Z (III-d)
[B- (ab) _n ] _k- Z (III-e)
[(Ba) _n -b] _k -Z (III-f)

  Examples of the initiator and the terminator include the coupling agents exemplified in the section of the method for producing a block copolymer described later.

(Physical properties of block copolymer)
The block copolymer has a peak top (peak height) of loss tangent (tan δ) in a range of −70 ° C. or more and 0 ° C. or less in the dynamic viscoelasticity spectrum. The value is preferably 0.6 or more and 2.0 or less. When the peak top (peak height) is within the above range, the high softening property and the elongation tend to be further improved in a balanced manner.

  From the viewpoint of further improving the high softness and elongation of the asphalt composition in a more balanced manner, the peak temperature range of the loss tangent (tan δ) is more preferably −50 ° C. or more and −10 ° C. or less, and further preferably − It is 40 degreeC or more and -15 degreeC or more.

  From the viewpoint of further improving the high softness and elongation of the asphalt composition, the value of peak top (peak height) is preferably 0.65 or more and 1.6 or less, and 0.7 or more and 1.5 or less. Is more preferable, and 0.75 or more and 1.4 or less are more preferable. The peak height and peak temperature of the loss tangent (tan δ) can be determined by the method described in the examples described later.

  The peak temperature of loss tangent (tan δ) is, for example, the ratio of the content of vinyl aromatic monomer units and conjugated diene monomer units in copolymer block (b), microstructure of conjugated diene compounds, water By controlling the addition rate and the like, it can be adjusted to have a loss tangent (tan δ) peak top (peak height) in the range of −70 ° C. or more and 0 ° C. or less. For example, when the ratio of the vinyl aromatic monomer unit in the copolymer block (b) is increased, the peak top of the loss tangent (tan δ) tends to be on the high temperature side, and the ratio of the vinyl aromatic monomer unit is decreased. The peak top of loss tangent (tan δ) tends to be on the low temperature side.

  In this embodiment, the weight average molecular weight (Mw) of the block copolymer is, for example, 100,000 or more and 500,000 or less, and 100,000 or more is preferable from the viewpoint of further improving the high softening property and the anti-aggregation performance. 140,000 or more is more preferable, 170,000 or more is more preferable, and 200,000 or more is particularly preferable. On the other hand, the weight average molecular weight of the block copolymer is preferably 500,000 or less, more preferably 460,000 or less, further preferably 420,000 or less, and particularly preferably 380,000 or less, from the viewpoint of further improving the low melt viscosity.

  In this embodiment, the lower limit value of the molecular weight distribution (Mw / Mn) of the block copolymer (ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn)) is the amount of the block copolymer added to the asphalt From the viewpoint of further reducing the low melt viscosity, 1.03 or more is preferred, 1.05 or more is more preferred, 1.11 or more is more preferred, and 1.20 or more is even more preferred. Further, from the viewpoint of excellent manufacturability of the asphalt composition, the amount of the block copolymer (partially hydrogenated block copolymer) added to the asphalt is reduced, and further, the low melt viscosity is further improved. The upper limit of the molecular weight distribution (Mw / Mn) of the polymer is preferably 2.0 or less, more preferably 1.7 or less, still more preferably 1.4 or less, and particularly preferably 1.3 or less. The weight average molecular weight (Mw), number average molecular weight (Mn), and molecular weight distribution (Mw / Mn) of the polymer can be determined by the methods described in the examples described later.

<Crosslinking agent (B)>
The asphalt composition of this embodiment contains a crosslinking agent. By including a crosslinking agent, the asphalt composition has excellent high softening properties, compatibility, and heat resistance stability. Although it does not specifically limit as a crosslinking agent, For example, sulfur, sulfur compounds, inorganic vulcanizing agents other than sulfur, oximes, nitroso compounds, polyamines, organic peroxides, resin crosslinking agents, isocyanate compounds, polyphosphoric acid, and crosslinking An auxiliary agent is mentioned, and from the viewpoint of further improving the softening property, compatibility, and heat stability, sulfur, a sulfur compound, and polyphosphoric acid are preferable.

<Asphalt (C)>
The asphalt composition of this embodiment contains asphalt. The asphalt is not particularly limited, but for example, asphalt obtained as a by-product during petroleum refining (petroleum asphalt), natural product (natural asphalt), or a mixture of these asphalts and petroleum, etc. Can be mentioned. Asphalt usually contains bitumen (bitumen) as a main component.

  Specific examples of the asphalt are not particularly limited, and examples thereof include straight asphalt, semi-blown asphalt, blown asphalt, solvent deasphalted asphalt, cut back asphalt added with tar, pitch, oil, and asphalt emulsion. Among these, from the viewpoint of availability, the asphalt is preferably straight asphalt. These may be used alone or in combination. Moreover, you may add aromatic heavy mineral oils, such as petroleum-type solvent extraction oil, aroma-type hydrocarbon process oil, or an extract, to various asphalts.

  The asphalt has a penetration (measured according to JIS-K2207) of preferably 30 or more and 300 or less, more preferably 50 or more and 250 or less, and still more preferably 60 or more and 200 or less. When the penetration of the asphalt is within the above range, the asphalt composition tends to have an excellent balance of softening point, elongation, melt viscosity, drilling resistance, and heat stability during storage.

  In the asphalt composition of this embodiment, the ratio of the block copolymer is 0.5 parts by mass or more and 20 parts by mass or less, preferably 2 parts by mass or more and 13 parts by mass or less, more preferably 100 parts by mass of asphalt. Is 3 parts by mass or more and 10 parts by mass or less. When the ratio of the block copolymer is 0.5 parts by mass or more, the high softening property is excellent, and when it is 20 parts by mass or less, the low melt viscosity is excellent.

  In the asphalt composition of the present embodiment, the ratio of the crosslinking agent is 0.03 parts by mass or more and 3 parts by mass or less, preferably 0.04 parts by mass or more and 2.5 parts by mass or less with respect to 100 parts by mass of asphalt. Yes, more preferably 0.05 parts by mass or more and 2.0 parts by mass or less. When the proportion of the crosslinking agent is 0.03 parts by mass or more, the softening point of the asphalt composition can be sufficiently increased, and when the proportion of the crosslinking agent is 3 parts by mass or less, the low melt viscosity is excellent, and the modified asphalt mixture , Both excellent workability and fluid resistance can be achieved.

  The ratio of the crosslinking agent to the entire asphalt composition is such that the conjugated diene copolymer and the asphalt have high compatibility, and the modified asphalt mixture has a high mass loss resistance and a high strength reduction at the time of oil adhesion, 0.02 mass% or more is preferable, 0.04 mass% or more is more preferable, and 0.06 mass% or more is further preferable. Further, the ratio of the crosslinking agent to the entire asphalt composition may be 20% by mass or more and 60% by mass or less from the viewpoint of obtaining an asphalt composition having a high penetration. The upper limit of the ratio of the crosslinking agent relative to the entire asphalt composition is preferably 1.0% by mass or less, and preferably 0.4% by mass or less from the viewpoint of obtaining an asphalt composition having a high penetration and being excellent in economic efficiency. More preferred is 0.2% by mass or less.

  In the present embodiment, the asphalt composition preferably includes a tackifying resin from the viewpoint of shortening the production time of the asphalt composition and further improving the compatibility and the anti-aggregation performance of the asphalt composition.

  Examples of the tackifying resin include, but are not limited to, rosin resins, hydrogenated rosin resins, terpene resins, coumarone resins, phenol resins, terpene-phenol resins, aromatic hydrocarbon resins, and aliphatic resins. A hydrocarbon resin etc. are mentioned.

  These tackifier resins can be used alone or in combination of two or more. As a more specific tackifying resin, a tackifying resin described in “Rubber / Plastic Compounding Chemicals” (edited by Rubber Digest Co., Ltd.) can be used. Aromatic hydrocarbon resins are preferred from the standpoint of more excellent compatibility and aggregate peeling resistance.

  The content of the tackifier resin in the asphalt composition is preferably more than 0 parts by mass and 200 parts by mass or less, more preferably 3 parts by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the block copolymer. preferable. By setting it as the content of the said range, it exists in the tendency for compatibility and anti-aggregate peeling performance to be further excellent.

  From the viewpoint of further improving the low melt viscosity and compatibility of the asphalt composition, the asphalt composition preferably contains oil. Although it does not specifically limit as oil, For example, both a mineral oil type softening agent or a synthetic resin type softening agent can be used. Although it does not specifically limit as a mineral oil type softening agent, Generally, a paraffinic oil, a naphthenic oil, an aromatic oil etc. are mentioned. In general, paraffinic hydrocarbons having 50% or more of carbon atoms in the oil are called “paraffinic oil”, and the number of carbon atoms of naphthenic hydrocarbons is Those having 30% or more and 45% or less are called “naphthenic oils”, and those having aromatic hydrocarbons occupying 35% or more are called “aromatic oils”.

  When the asphalt composition contains a mineral oil softener, the workability of the asphalt composition is further improved. As the mineral oil softener, paraffinic oil is preferable from the viewpoint of further improving the low melt viscosity and low temperature performance of the asphalt composition, and from the viewpoint of further improving the low melt viscosity and compatibility of the asphalt composition. Naphthenic oils are preferred.

  The synthetic resin softener is not particularly limited, and examples thereof include polybutene and low molecular weight polybutadiene, and polybutene and low molecular weight polybutadiene are preferred.

  The content of oil in the asphalt composition is 10 parts by mass or more and 50 parts by mass with respect to 100 parts by mass of the block copolymer, from the viewpoint of suppressing oil bleed and ensuring that the asphalt composition has practically sufficient mechanical strength. Is preferably 15 parts by mass or more and 40 parts by mass or less, and more preferably 20 parts by mass or more and 30 parts by mass or less.

  The asphalt composition may further include a foaming agent from the viewpoint of further excellent low melt viscosity and further shortening the production time of the asphalt composition.

  Although it does not specifically limit as a foaming agent, For example, sodium hydrogencarbonate, ammonium carbonate, diazoaminobenzene, N, N'- dinitrosopentamethylenetetramine, 2,2'-azobis (isobutyronitrile) etc. are mentioned. . These foaming agents can be used individually by 1 type or in combination of 2 or more types. Among these, diazoaminobenzene, N, N′-dinitrosopentamethylenetetramine, and 2,2′-azobis (isobutyronitrile) are preferable from the viewpoint of further excellent compatibility.

  The ratio of the foaming agent to the entire asphalt composition is preferably 0.1% by mass or more, more preferably 0.3% by mass or more from the viewpoint of further improving the low melt viscosity and further reducing the production time of the asphalt composition. preferable. Further, the ratio of the foaming agent to the entire asphalt composition is preferably 3% by mass or less, more preferably 2% by mass or less, and still more preferably 1% by mass or less, from the viewpoint of excellent economic efficiency.

  The asphalt composition may contain other additives generally used as a compounding material for thermoplastic resins or rubbery polymers. Other additives include, for example, inorganic fillers, lubricants, mold release agents, plasticizers, antioxidants, stabilizers, flame retardants, antistatic agents, organic fibers, glass fibers, carbon fibers, metal whiskers, etc. Agents, colorants, pigments, viscosity modifiers, anti-peeling agents, and pigment dispersants. The content of other additives is not particularly limited, and is usually 50 parts by mass or less with respect to 100 parts by mass of asphalt.

  The inorganic filler is not particularly limited, but for example, calcium carbonate, magnesium carbonate, magnesium hydroxide, calcium sulfate, barium sulfate, silica, clay, talc, mica, wollastonite, montmorillonite, zeolite, alumina, titanium oxide, Examples thereof include magnesium oxide, zinc oxide, slug wool, and glass fiber.

  The lubricant / release agent is not particularly limited, and examples thereof include pigments such as carbon black and iron oxide, stearic acid, behenic acid, zinc stearate, calcium stearate, magnesium stearate, and ethylene bisstearamide. It is done.

  Although it does not specifically limit as a stabilizer, Various stabilizers, such as antioxidant and a light stabilizer, are mentioned.

  Examples of the antioxidant include, but are not limited to, phenolic antioxidants such as radical scavengers, phosphorus antioxidants such as peroxide decomposers, and sulfur antioxidants. Moreover, you may use the antioxidant which has both performances together. These antioxidants may be used alone or in combination of two or more. Among these, a phenolic antioxidant is preferable from the viewpoint that the heat resistance stability (heat aging resistance) of the block copolymer is further excellent and further gelation can be suppressed. The antioxidant is not particularly limited, and examples thereof include 2,6-di-t-butyl-4-methylphenol, n-octadecyl-3- (4′-hydroxy-3 ′, 5′-di-t- Butylphenyl) propionate, 2,2′-methylenebis (4-methyl-6-tert-butylphenol), 2,2′-methylenebis (4-ethyl-6-tert-butylphenol), 2,4-bis [(octylthio) Methyl] -o-cresol, 2-t-butyl-6- (3-t-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate, 2,4-di-t-amyl-6 -[1- (3,5-di-t-amyl-2-hydroxyphenyl) ethyl] phenyl acrylate, 2- [1- (2-hydroxy-3,5-di-tert-pentylphenyl)] acrylate Hindered phenol-based antioxidants such as dilauryl thiodipropionate, lauryl stearyl thiodipropionate pentaerythritol-tetrakis (β-lauryl thiopropionate) and the like; tris (nonylphenyl) Examples thereof include phosphorous antioxidants such as phosphite and tris (2,4-di-t-butylphenyl) phosphite.

  The light stabilizer is not particularly limited. For example, 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-t-butylphenyl) benzo Benzotriazole ultraviolet absorbers such as triazole and 2- (2′-hydroxy-3 ′, 5′-di-t-butylphenyl) -5-chlorobenzotriazole; benzophenones such as 2-hydroxy-4-methoxybenzophenone UV absorbers; hindered amine light stabilizers and the like.

  The asphalt composition tends to further prevent peeling between the asphalt composition and the aggregate when the asphalt composition and the aggregate are mixed by including an anti-peeling agent. As the peeling preventive, for example, a resin acid is suitable, which is a polycyclic diterpene having 20 carboxyl groups and having a carboxyl group, and is abietic acid, dehydroabietic acid, neoabietic acid, pimaric acid, isopimaric acid, and parastrinic acid Rosin containing at least one selected from the group consisting of: Moreover, since a fatty acid or a fatty acid amide functions as a peeling inhibitor and a lubricant, a fatty acid or a fatty acid amide can be applied as a peeling inhibitor.

  The asphalt composition may or may not contain a rubber component other than the block copolymer (hereinafter also simply referred to as “rubber component”). The rubber component other than the block copolymer (partially hydrogenated block copolymer) is not particularly limited, and examples thereof include natural rubber and synthetic rubber. Examples of the synthetic rubber include polyisoprene rubber, polybutadiene rubber (BR), styrene butadiene rubber (SBR), modified styrene butadiene rubber (modified SBR), styrene-butadiene-styrene block copolymer (SBS), and styrene-ethylene-butylene. -Olefin elastomer such as styrene block copolymer (SEBS), styrene-butylene-butadiene-styrene copolymer (SBBS), ethylene propylene copolymer (EPDM); chloroprene rubber, acrylic rubber, ethylene vinyl acetate copolymer (EVA), ethylene-ethyl acrylate copolymer (EEA), nitrile butadiene rubber (NBR) and the like.

  As rubber components other than the block copolymer, polyisoprene rubber, polybutadiene rubber, styrene butadiene rubber, styrene-butazine-styrene block copolymer, ethylene acetate Vinyl copolymers are preferred, and polybutadiene rubber and styrene-butadiene-styrene block copolymers are more preferred.

  The rubber component other than the block copolymer may have a functional group. As the rubber component other than the block copolymer, an olefin-based elastomer and an olefin-based elastomer having a functional group are preferable from the viewpoint of further improving the flow resistance of the asphalt composition.

  When the rubber component other than the block copolymer has a functional group, the functional group is selected from the group consisting of a hydroxyl group, an acid anhydride group, an epoxy group, an amino group, an amide group, a silanol group, and an alkoxysilane group. It preferably has at least one functional group. Rubber components other than the block copolymer (partially hydrogenated block copolymer) can be used alone or in combination of two or more.

  The content of the rubber component other than the block copolymer in the asphalt composition is preferably 0.5 parts by mass or more and 400 parts by mass or less when the above-described block copolymer is 100 parts by mass. More preferably, they are 5 mass parts or more and 300 mass parts or less, More preferably, they are 1 mass part or more and 200 mass parts or less, Most preferably, they are 5 mass parts or more and 150 mass parts or less. When the content of the rubber component other than the block copolymer is within the above range, the compatibility and the anti-aggregate performance tend to be further improved.

  The asphalt composition may contain a resin component other than the block copolymer of the present embodiment. The resin component other than the block copolymer of the present embodiment is not limited to the following, but for example, polyethylene (PE), low density polyethylene (low density PE), polyvinyl chloride (PVC), polyamide (PA), polystyrene ( PS), acrylic resin, polycarbonate (PC), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyvinylidene fluoride (PVDF), Teflon (registered trademark) (PTFE), polyether ether ketone (PEEK), polyphenylene sulfide Examples thereof include thermoplastic resins such as (PPS), polyimide (PI), and polyamideimide (PAI).

  As resin components other than the block copolymer of the present embodiment, polyethylene (PE), low density polyethylene (low density PE), polyvinyl chloride (PVC) from the viewpoint of further excellent compatibility and anti-aggregation performance. ) And polyamide (PA) are more preferable.

  The resin component other than the block copolymer may have a functional group. When the resin component other than the block copolymer has a functional group, the functional group is selected from the group consisting of a hydroxyl group, an acid anhydride group, an epoxy group, an amino group, an amide group, a silanol group, and an alkoxysilane group. It preferably has at least one functional group. Resin components other than the block copolymer can be used alone or in combination of two or more.

  The content of the resin component other than the block copolymer in the asphalt composition is preferably 0.5 parts by mass or more and 400 parts by mass or less with respect to 100 parts by mass of the block copolymer, 0.5 parts by mass It is more preferably 300 parts by mass or less, further preferably 1 part by mass or more and 200 parts by mass or less, and particularly preferably 5 parts by mass or more and 150 parts by mass or less. When the content of the resin component other than the block copolymer is in the above range, the compatibility of the asphalt composition and the anti-aggregate performance tend to be further improved.

  The asphalt composition of this embodiment is a polymer mainly composed of a vinyl aromatic monomer unit having a weight average molecular weight (Mw) of 5,000 or more and 30,000 or less as a resin component other than the block copolymer. (Hereinafter also referred to as “low molecular weight vinyl aromatic polymer”). The low molecular weight vinyl aromatic polymer is preferably mainly composed of vinyl aromatic monomer units contained in the polymer block (a) in the present embodiment, and mainly composed of monomer units derived from polystyrene. It is more preferable.

  The lower limit of the content of the low molecular weight vinyl aromatic polymer is preferably 0.5 parts by mass or more with respect to 100 parts by mass of the block copolymer, and 1.0 part by mass from the viewpoint of further improving the low melt viscosity. The above is more preferable, 2.0 parts by mass or more is further preferable, and 3.0 parts by mass or more is particularly preferable. Further, the upper limit value of the content of the low molecular weight vinyl aromatic polymer is preferably 5.0 parts by mass or less with respect to 100 parts by mass of the block copolymer, from the viewpoint of further improving the high softening property. Part or less is more preferable, 3.0 parts by weight or less is more preferable, and 2.0 parts by weight or less is particularly preferable.

  A commercially available low molecular weight vinyl aromatic polymer may be mixed with the block copolymer of this embodiment.

<Method for producing block copolymer>
The production method of the block copolymer is not limited to the following, for example, in a hydrocarbon solvent, using a lithium compound as a polymerization initiator, polymerizing at least a conjugated diene monomer and a vinyl aromatic monomer, A polymerization step is performed to obtain a block copolymer containing a polymer block (a) mainly composed of a vinyl aromatic monomer unit and a polymer block (b) having at least a conjugated diene monomer unit. After the step, a hydrogenation step of adding hydrogen to a part of the double bond in the conjugated diene monomer unit of the obtained block copolymer is performed, and the resulting block copolymer (partially hydrogenated block copolymer) is obtained. It can be produced by performing a solvent removal step of removing the solvent of the solution containing the polymer).

  In the polymerization step, for example, a block copolymer is obtained by polymerizing a monomer containing at least a conjugated diene monomer and a vinyl aromatic monomer in a hydrocarbon solvent using a lithium compound as a polymerization initiator. Can do.

  The hydrocarbon solvent used in the polymerization step is not particularly limited. For example, aliphatic hydrocarbons such as butane, pentane, hexane, isopentane, heptane, and octane; cyclopentane, methylcyclopentane, cyclohexane, methylcyclohexane, ethylcyclohexane, etc. And aromatic hydrocarbons such as benzene, toluene, ethylbenzene, and xylene. These hydrocarbon solvents can be used individually by 1 type or in combination of 2 or more types.

  Although it does not specifically limit as a lithium compound used as a polymerization initiator in a superposition | polymerization process, For example, the compound which combined one or more lithium atoms in molecules, such as an organic monolithium compound, an organic dilithium compound, and an organic polylithium compound, is mentioned. . Such an organic lithium compound is not particularly limited. For example, ethyllithium, n-propyllithium, isopropyllithium, n-butyllithium, sec-butyllithium, tert-butyllithium, hexamethylenedilithium, butadienyl Examples include dilithium and isoprenyl dilithium. These lithium compounds can be used singly or in combination of two or more.

  The conjugated diene monomer is not particularly limited. For example, 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 1,3- Examples include diolefins having a pair of conjugated double bonds such as pentadiene, 2-methyl-1,3-pentadiene, and 1,3-hexadiene. Among these, 1,3-butadiene and isoprene are preferable. From the viewpoint of further improving the mechanical strength, 1,3-butadiene is more preferable. These conjugated diene monomers can be used singly or in combination of two or more.

  Although it does not specifically limit as a vinyl aromatic monomer, For example, styrene, (alpha) -methylstyrene, p-methylstyrene, divinylbenzene, 1,1-diphenylethylene, N, N-dimethyl-p-aminoethyl styrene, And vinyl aromatic compounds such as N, N-diethyl-p-aminoethylstyrene. Among these, styrene is preferable from the viewpoint of excellent economic efficiency. These vinyl aromatic monomers can be used individually by 1 type or in combination of 2 or more types.

  Examples of the monomer other than the conjugated diene monomer and the vinyl aromatic monomer include monomers copolymerizable with the conjugated diene monomer and / or the vinyl aromatic monomer.

  In the polymerization step, for example, the polymerization rate is adjusted, the microstructure of the polymerized conjugated diene monomer unit (ratio of cis, trans, and vinyl) is adjusted, or the conjugated diene monomer and the vinyl aromatic unit. In order to adjust the reaction ratio with the monomer, a polar compound and / or a randomizing agent can be used.

  Although it does not specifically limit as a polar compound or a randomizing agent, For example, ethers, such as tetrahydrofuran, diethylene glycol dimethyl ether, diethylene glycol dibutyl ether; Triethylamine, N, N, N ', N'-tetramethylethylenediamine (henceforth "TMEDA") Amines such as thioethers, phosphines, phosphoramides, alkylbenzene sulfonates, and alkoxides of potassium and sodium.

  The polymerization method carried out in the polymerization step of the block copolymer is not particularly limited, and is a known method (for example, Japanese Patent Publication No. 36-19286, Japanese Patent Publication No. 43-171979, Japanese Patent Publication No. 46-32415, JP-B-49-36957, JP-B-48-2423, JP-B-48-4106, JP-B-56-28925, JP-A-59-166518, JP-A-60-186777, etc. Can be applied.

  The block copolymer may be coupled using a coupling agent. Although it does not specifically limit as a coupling agent, Bifunctional or more arbitrary coupling agents can be used. Although it does not specifically limit as a bifunctional coupling agent, For example, Bifunctional halogenated silanes, such as dichlorosilane, monomethyldichlorosilane, dimethyldichlorosilane; Diphenyldimethoxysilane, diphenyldiethoxysilane, dimethyldimethoxysilane, dimethyldi Bifunctional alkoxysilanes such as ethoxysilane; Bifunctional halogenated alkanes such as dichloroethane, dibromoethane, methylene chloride, dibromomethane; dichlorotin, monomethyldichlorotin, dimethyldichlorotin, monoethyldichlorotin, diethyldichlorotin, monobutyl Bifunctional tin halides such as dichlorotin and dibutyldichlorotin; dibromobenzene, benzoic acid, CO, 2-chloropropene and the like.

  The trifunctional coupling agent is not particularly limited, and examples thereof include trifunctional halogenated alkanes such as trichloroethane and trichloropropane; trifunctional halogenated silanes such as methyltrichlorosilane and ethyltrichlorosilane; methyltrimethoxysilane; And trifunctional alkoxysilanes such as phenyltrimethoxysilane and phenyltriethoxysilane.

  The tetrafunctional coupling agent is not particularly limited, and examples thereof include tetrafunctional halogenated alkanes such as carbon tetrachloride, carbon tetrabromide, and tetrachloroethane; tetrafunctional halogenated silanes such as tetrachlorosilane and tetrabromosilane. Tetrafunctional silanes such as tetramethoxysilane and tetraethoxysilane; tetrafunctional tin halides such as tetrachlorotin and tetrabromotin;

  The pentafunctional or higher functional coupling agent is not particularly limited. For example, polyhalogen such as 1,1,1,2,2-pentachloroethane, perchloroethane, pentachlorobenzene, perchlorobenzene, octabromodiphenyl ether, decabromodiphenyl ether, and the like. And hydrocarbon compounds. In addition, polyvinyl compounds such as epoxidized soybean oil, 2 to 6 functional epoxy group-containing compounds, carboxylic acid esters, and divinylbenzene can also be used. These coupling agents are used singly or in combination of two or more.

  In this embodiment, it is preferable to perform the deactivation process which deactivates the active terminal of a block copolymer after a superposition | polymerization process. The active terminal of the polymer can be deactivated by reacting the active hydrogen-containing compound with the active terminal. Although it does not specifically limit as a compound which has active hydrogen, From a viewpoint with which economical efficiency is excellent, alcohol and water can be mentioned.

  In the present embodiment, in the hydrogenation step, hydrogen is added to a part of the double bond in the conjugated diene monomer unit of the block copolymer obtained in the polymerization step. The hydrogenation catalyst used in the hydrogenation step is not particularly limited. For example, a supported catalyst in which a metal such as Ni, Pt, Pd, or Ru is supported on a carrier such as carbon, silica, alumina, or diatomaceous earth. Homogeneous catalysts; so-called Ziegler type catalysts using organic salts such as Ni, Co, Fe, Cr or the like and acetylacetone salts and reducing agents such as organic Al; so-called organic complex catalysts such as organometallic compounds such as Ru and Rh; and A homogeneous catalyst using organic Li, organic Al, organic Mg or the like as a reducing agent in the titanocene compound can be mentioned. Among these, a homogeneous catalyst system using organic Li, organic Al, organic Mg, or the like as a reducing agent for the titanocene compound is preferable from the viewpoint of economy, colorability of the polymer, or adhesive strength.

  The method for the hydrogenation step is not particularly limited. For example, the method described in JP-B-42-8704 and JP-B-43-6636, preferably JP-B-63-4841 and JP-B-63. And the method described in Japanese Patent No. 5401. Specifically, a hydrogenation step can be performed in the presence of a hydrogenation catalyst in an inert solvent to obtain a hydrogenated block copolymer solution. The hydrogenation step is preferably performed after the deactivation step from the viewpoint of high hydrogenation activity. The hydrogenation step can be performed either batchwise, continuously, or a combination thereof.

  In the hydrogenation step, the conjugated double bond of the vinyl aromatic monomer unit may be hydrogenated. The upper limit of the hydrogenation rate of the conjugated double bond in the total vinyl aromatic monomer unit is, for example, 30 mol% or less, 10 mol% or less, or 3 mol% or less, based on the total amount of unsaturated groups in the vinyl aromatic. The lower limit can be, for example, 0.1 mol% or more, or 0 mol%.

  As a polymerization initiator, monomer, coupling agent or terminator, at least one function selected from the group consisting of a hydroxyl group, an acid anhydride group, an epoxy group, an amino group, an amide group, a silanol group, and an alkoxysilane group Using a compound having a group, the resulting block copolymer (partially hydrogenated block copolymer) comprises a hydroxyl group, an acid anhydride group, an epoxy group, an amino group, an amide group, a silanol group, and an alkoxysilane group. It is preferable that at least one functional group selected from the group is added.

  As the polymerization initiator having a functional group, a polymerization initiator containing a nitrogen-containing group is preferable. The polymerization initiator containing a nitrogen-containing group is not particularly limited. For example, dioctylaminolithium, di-2-ethylhexylaminolithium, ethylbenzylaminolithium, (3- (dibutylamino) -propyl) lithium, piperidy Nolithium and the like can be mentioned.

  As the monomer having a functional group, a monomer having a nitrogen-containing group is preferable. The monomer having a nitrogen-containing group is not particularly limited. For example, N, N-dimethylvinylbenzylamine, N, N-diethylvinylbenzylamine, N, N-dipropylvinylbenzylamine, N, N- Dibutylvinylbenzylamine, N, N-diphenylvinylbenzylamine, 2-dimethylaminoethylstyrene, 2-diethylaminoethylstyrene, 2-bis (trimethylsilyl) aminoethylstyrene, 1- (4-N, N-dimethylaminophenyl) -1-phenylethylene, N, N-dimethyl-2- (4-vinylbenzyloxy) ethylamine, 4- (2-pyrrolidinoethyl) styrene, 4- (2-piperidinoethyl) styrene, 4- (2-hexamethylene) Iminoethyl) styrene, 4- (2-morpholinoethyl) styrene, 4 (2-thiazinoethyl) styrene, 4- (2-N-methylpiperazinoethyl) styrene, 1-((4-vinylphenoxy) methyl) pyrrolidine, 1- (4-vinylbenzyloxymethyl) pyrrolidine and the like It is done.

  As the coupling agent and terminator containing a functional group, among the aforementioned coupling agent and terminator, a group consisting of a hydroxyl group, an acid anhydride group, an epoxy group, an amino group, an amide group, a silanol group, and an alkoxysilane group And coupling agents having at least one functional group selected from:

  These compounds having a functional group can be used singly or in combination of two or more. Among these, a coupling agent and a terminator having a nitrogen-containing group or an oxygen-containing group are preferable. Although it does not specifically limit as a coupling agent and terminator which have a nitrogen-containing group or an oxygen-containing group, For example, N, N, N ', N'-tetraglycidyl metaxylenediamine, tetraglycidyl-1,3-bisamino Methylcyclohexane, tetraglycidyl-p-phenylenediamine, tetraglycidyldiaminodiphenylmethane, diglycidylaniline, γ-caprolactone, γ-glycidoxyethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyl Triphenoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropyldiethylethoxysilane, 1,3-dimethyl-2-imidazolidinone, 1,3-diethyl-2-imidazolidinone, N, N'-dimethylpropylene A, and N- methylpyrrolidone.

  In the solvent removal step, the solvent of the polymer solution containing the block copolymer is removed. The method for removing the solvent is not particularly limited, and examples thereof include a steam stripping method and a direct solvent removal method.

  The amount of residual solvent in the block copolymer obtained by the solvent removal step may be small, and is preferably 2% by mass or less, more preferably 0.5% by mass or less, still more preferably 0.2% by mass or less, and particularly preferably 0. It is 05 mass% or less (preferably 0.01 mass% or less, more preferably 0 mass%). Usually, the amount of residual solvent in the block copolymer (partially hydrogenated block copolymer) is preferably 0.01% by mass or more and 0.1% by mass or less from the viewpoint of excellent economic efficiency.

  From the viewpoint of further improving the heat stability of the block copolymer and suppressing gelation, it is preferable to add the antioxidant exemplified in the section of the asphalt composition to the block copolymer.

  From the viewpoint of preventing coloration of the block copolymer and improving mechanical strength, the deashing step of removing the metal in the solution containing the block copolymer, the solution containing the block copolymer, before the solvent removal step A neutralization step for adjusting the pH may be performed. For example, an acid may be added and / or a carbon dioxide gas may be added.

[Method for producing asphalt composition]
The asphalt composition comprises asphalt, a block copolymer of 5 to 20 parts by weight with respect to 100 parts by weight of asphalt, and a crosslinking agent of 0.03 to 3 parts by weight with respect to 100 parts by weight of asphalt. Can be produced by mixing at least.

  From the viewpoint of sufficiently reacting the block copolymer and the crosslinking agent, the mixing time after adding the crosslinking agent to the asphalt composition excluding the crosslinking agent is preferably 20 minutes or more, more preferably 40 minutes or more, and still more preferably. 60 minutes or more, particularly 90 minutes or more. Further, from the viewpoint of suppressing thermal deterioration of the block copolymer, the mixing time after adding the crosslinking agent to the asphalt composition excluding the crosslinking agent is preferably 5 hours or less, more preferably 3 hours or less.

  The mixing method is not particularly limited, and can be performed using any mixer. Examples of the mixer include a melt kneader such as an extruder, a kneader, and a Banbury mixer, a stirrer such as a vertical impeller and a side arm type impeller, a homogenizer including an emulsifier, and a pump.

  In the manufacturing method of the asphalt composition of this embodiment, it is preferable to mix asphalt, a block copolymer, a crosslinking agent, and arbitrary additives using the stirring tank etc. in the range of 140 to 220 degreeC.

<Modified asphalt mixture>
The modified asphalt mixture includes the asphalt composition of this embodiment and the aggregate.

  The aggregate is not particularly limited, and any aggregate can be used as long as it is an aggregate for a pavement described in “Asphalt Pavement Summary” issued by the Japan Road Association. Specifically, aggregates include crushed stone, cobblestone, gravel, steel slag, and the like. In addition, asphalt-coated aggregates and recycled aggregates obtained by coating these aggregates with asphalt can also be used. In addition, similar aggregate materials such as granular materials, artificial fired aggregates, fired foam aggregates, artificial lightweight aggregates, ceramic grains, loxobite, aluminum grains, plastic grains, ceramics, emery, construction waste, fibers, etc. Can be used.

  In general, aggregates are roughly classified into coarse aggregates, fine aggregates, and fillers, but any of coarse aggregates, fine aggregates, and fillers may be used as the aggregates of the present embodiment. be able to.

  Coarse aggregate refers to an aggregate that remains on the 2.36 mm sieve. Generally, the types of coarse aggregate include No. 7 crushed stone with a particle size range of 2.5 mm to 5 mm, and 6 with a particle size range of 5 mm to 13 mm. There are No. 5 crushed stone, No. 5 crushed stone having a particle size range of 13 mm to 20 mm, and No. 4 crushed stone having a particle size range of 20 mm to 30 mm. In the asphalt mixture of the present embodiment, an aggregate obtained by mixing one or two or more kinds of coarse aggregates having various particle diameter ranges, a synthesized aggregate, or the like can be used. These coarse aggregates may be coated with straight asphalt of about 0.3 mass% or more and 1 mass% or less with respect to the aggregate.

  Fine aggregate means an aggregate that passes (passes) through a 2.36 mm sieve and stops (turns on) a 0.075 mm sieve. Examples of fine aggregates include river sand, hill sand, mountain sand, Sea sand, screenings, crushed stone dust, silica sand, artificial sand, glass cullet, foundry sand, recycled aggregate crushed sand and the like can be mentioned.

  A filler is an aggregate that passes through a 0.075 mm sieve. Examples of the filler include screening filler, stone powder, slaked lime, cement, incinerator ash, clay, talc, fly ash, carbon Black etc. are mentioned. In addition to these, rubber filler particles, cork powder particles, wood powder particles, resin powder particles, fiber powder particles, pulp, artificial aggregate and the like that pass (pass) the 0.075 mm sieve can be used as the filler.

  These aggregates can be used alone or in combination of two or more.

  The modified asphalt mixture can be produced by mixing at least the asphalt composition of the present embodiment and the aggregate, and the mixing method is not particularly limited.

  The mixing temperature of the asphalt composition and the aggregate can usually be in the range of 120 ° C. or higher and 200 ° C. or lower.

  The content of the aggregate with respect to the whole modified asphalt mixture is preferably 85% by mass or more and 98% by mass from the viewpoint of obtaining a modified asphalt mixture having excellent mass loss resistance at the time of oil adhesion and excellent strength reduction resistance. It is below, More preferably, it is 90 to 97 mass%.

  As a method for producing the modified asphalt mixture, for example, when asphalt and aggregate are mixed, the block copolymer (partially hydrogenated block copolymer) of this embodiment is directly mixed to modify the asphalt. The so-called plant mix method can be used.

<Use of asphalt composition and modified asphalt mixture>
The asphalt composition and the modified asphalt mixture of this embodiment are D.I. Edited by White Oak, Shell Bitumen U. K. Can be used in a variety of applications as described in The Shell Bitumen Handbook, published in the UK in 1990. Other applications include waterproof sheets, roof coatings, primer adhesives for waterproof sheets, sealing adhesives for paving, adhesives for recycled asphalt paving, cold prepared asphalt concrete. These include binders, fiberglass mat binders, concrete slip coats, protective coats for concrete, pipelines and cracking of steel parts.

  The pavement form using the modified asphalt mixture of the present embodiment is not limited to the following, but is a dense grained pavement form, a drainable pavement form, a water-permeable pavement form, a dense grained gap asphalt pavement form, a crushed stone mastic asphalt pavement form, a color. Pavement forms, semi-flexible pavement forms, water-retaining pavement forms, and thin-layer pavement forms are exemplified.

  Moreover, it does not specifically limit as a manufacturing method for obtaining each pavement form, For example, a thermal construction method, an intermediate temperature construction method, a normal temperature construction method etc. are mentioned.

  The asphalt mixture used in the dense-graded pavement form has a total aggregate amount of 100% by mass, coarse aggregates of 40% to 55% by mass, and fine bones from the viewpoint of further improving flow resistance and slip resistance. It is preferable to contain 40 mass% or more and 55 mass% or less of material, and 3 mass% or more and 10 mass% or less of filler. The modified asphalt mixture used for the dense-graded pavement has an asphalt composition of 5 parts by mass or more and 7 parts by mass or less with respect to 100 parts by mass of the aggregate, and in this embodiment with respect to 100 parts by mass of asphalt. The block copolymer is preferably 3 parts by mass or more and 5.5 parts by mass or less.

  From the viewpoint of further improving drainage, visibility, and noise resistance, the modified asphalt mixture used in the drainage pavement form has a total aggregate amount of 100% by mass, and a coarse aggregate of 60% by mass to 85% by mass. Hereinafter, it is preferable to contain 5 to 20% by mass of fine aggregate and 3 to 20% by mass of filler. The modified asphalt mixture used in the drainage pavement form has an asphalt composition of not less than 4 parts by mass and not more than 6 parts by mass with respect to 100 parts by mass of the aggregate, and this embodiment is based on 100 parts by mass of asphalt. It is preferable that the block copolymer in is 5 to 10 parts by mass.

  From the viewpoint of further improving the water permeability, the modified asphalt mixture used in the water-permeable pavement form is set such that the total amount of aggregate is 100 mass%, coarse aggregate is 60 mass% to 85 mass%, and fine aggregate is 5 mass. % To 20% by mass, and 3% to 20% by mass of filler is preferable. The modified asphalt mixture used for the water-permeable pavement has an asphalt composition of 4 parts by mass or more and 6 parts by mass or less with respect to 100 parts by mass of the aggregate, and this embodiment is based on 100 parts by mass of asphalt. It is preferable that the block copolymer in is more than 0 and 6 parts by weight or less.

  The modified asphalt mixture used in the dense-gap gap pavement form has a total aggregate amount of 100% by mass and a coarse aggregate of 50% from the viewpoint of further improving the wear resistance, flow resistance, durability and slip resistance. % To 60% by mass, fine aggregate 30% to 40% by mass, and filler 3% to 10% by mass. The modified asphalt mixture used in the dense-gap gap paving form has an asphalt composition of 4.5 parts by mass or more and 6 parts by mass or less with respect to 100 parts by mass of the aggregate, and with respect to 100 parts by mass of asphalt, It is preferable that the block copolymer in this embodiment is 5 parts by mass or more and 12 parts by mass or less.

  The modified asphalt mixture used in the crushed stone mastic asphalt pavement form has a total amount of aggregate of 100% by mass from the viewpoint of further improving wear, water impermeability, stress relaxation, flow resistance, and noise resistance, It is preferable to contain 55 to 70% by mass of coarse aggregate, 15 to 30% by mass of fine aggregate, and 5 to 15% by mass of filler. The modified asphalt mixture used in the crushed stone mastic asphalt pavement form has an asphalt composition of 5.5 parts by mass or more and 8 parts by mass or less with respect to 100 parts by mass of the aggregate, and with respect to 100 parts by mass of asphalt, It is preferable that the block copolymer of this embodiment is 4 mass parts or more and 10 mass parts or less.

  The modified asphalt mixture used in the water-retaining pavement form further suppresses the increase in pavement temperature and further improves the water retentivity, so that the total amount of aggregate is 100% by mass and the coarse aggregate is 60% by mass or more 85%. It is preferable to contain 5 mass% or less, fine aggregate 5 mass% or more and 20 mass% or less, and filler 3 mass% or more and 20 mass% or less. The modified asphalt mixture used in the water-retaining pavement form has an asphalt composition of 4 parts by mass or more and 6 parts by mass or less with respect to 100 parts by mass of the aggregate, and this embodiment is based on 100 parts by mass of asphalt. The block copolymer is preferably 4 parts by mass or more and 10 parts by mass or less. The modified asphalt mixture used in the form of water-retaining pavement preferably has a porosity of about 15% or more and 20% or less, and is filled with a water-retaining material such as cement or gypsum.

  The modified asphalt mixture used for the thin-layer pavement form has a total aggregate amount of 100% by mass and a coarse aggregate of 60% by mass or more and 85% by mass from the viewpoint of further improving economy, work period shortening and workability. % Or less, 5 to 20% by mass of fine aggregate, and 3 to 20% by mass of filler. The modified asphalt mixture used in the thin pavement form has an asphalt composition of 4 parts by mass or more and 6.5 parts by mass or less with respect to 100 parts by mass of the aggregate. The block copolymer in the embodiment is preferably 4 parts by mass or more and 8 parts by mass or less. The modified asphalt mixture used in the thin pavement form is preferably No. 7 crushed stone having a coarse aggregate particle size range of 2.5 mm to 5 mm.

  The asphalt composition of this embodiment can also be suitably used for asphalt waterproof sheets. If the asphalt composition of this embodiment is used, the softening point of an asphalt waterproof sheet can be made high and a low-temperature bending characteristic can be improved.

  Moreover, it does not specifically limit as a manufacturing method for obtaining each pavement form, For example, a thermal construction method, an intermediate temperature construction method, a normal temperature construction method etc. are mentioned.

  Hereinafter, specific examples and comparative examples will be specifically described, but the present invention is not limited thereto.

<Measurement method>
The measuring method of a block copolymer is shown below.

(Measurement of vinyl content and hydrogenation rate of block copolymer)
The vinyl content in the block copolymer and the hydrogenation rate of the unsaturated group in the conjugated diene monomer unit were measured under the following conditions by nuclear magnetic resonance spectrum analysis (NMR).

The block copolymer was precipitated and recovered by adding a large amount of methanol to the reaction solution containing the block copolymer before the hydrogenation reaction. Subsequently, this block copolymer was extracted with acetone, and the block copolymer was vacuum-dried. This was used as a sample for ¹ H-NMR measurement, and the vinyl content of the block copolymer was measured.

The block copolymer was precipitated and recovered by adding a large amount of methanol to the reaction solution containing the block copolymer after the hydrogenation reaction. Next, the block copolymer was extracted with acetone, and the block copolymer was vacuum-dried. This was used as a sample for ¹ H-NMR measurement to measure the hydrogenation rate.

The conditions for ¹ H-NMR measurement are described below.
Measuring instrument: JNM-LA400 (manufactured by JEOL)
Solvent: Deuterated chloroform Measurement sample: Extracted sample before and after hydrogenation of polymer Sample concentration: 50 mg / mL
Observation frequency: 400 MHz
Chemical shift criteria: TMS (tetramethylsilane)
Pulse delay: 2.904 seconds Number of scans: 64 times Pulse width: 45 °
Measurement temperature: 26 ° C

(Measurement of content (TS) of vinyl aromatic monomer unit (styrene) in block copolymer)
A certain amount of block copolymer is dissolved in chloroform, and absorption wavelength (262 nm) due to the vinyl aromatic compound component (styrene) in the solution using an ultraviolet spectrophotometer (manufactured by Shimadzu Corporation, UV-2450) The peak intensity of was measured. From the obtained peak intensity, the content (TS) of vinyl aromatic monomer units (styrene) in the block copolymer was calculated using a calibration curve.

(Measurement of content (BS) of polymer block mainly composed of vinyl aromatic monomer unit in block copolymer)
I. M.M. Kolthoff, et al. , J .; Polym. Sci. , 1946, Vol. 1, p. The content (BS) of the polymer block (a) mainly composed of vinyl aromatic monomer units in the block copolymer using the following polymer decomposition solution in the osmium tetroxide decomposition method according to 429 Was measured.
Measurement sample: sample taken before hydrogenating block copolymer Polymer decomposition solution: solution of 0.1 g of osmium tetroxide dissolved in 125 mL of tertiary butanol

(Measurement method of continuous vinyl aromatic monomer unit content)
The BS measurement sample was analyzed by GPC. The analysis conditions were the same as the following (measurement of weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) of the block copolymer). The continuous vinyl aromatic monomer unit content was determined from the obtained molecular weight distribution.

(Measurement of weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) of block copolymer)
The weight average molecular weight (Mw) of the block copolymer is based on the molecular weight of the peak of the chromatogram using a calibration curve (created using the peak molecular weight of standard polystyrene) obtained from measurement of commercially available standard polystyrene. Asked. The measurement software was HLC-8320EcoSEC collection, and the analysis software was HLC-8320 analysis. The molecular weight distribution (Mw / Mn) of the block copolymer was determined from the ratio of the weight average molecular weight (Mw) in terms of polystyrene and the number average molecular weight (Mn). The measurement conditions are shown below.
GPC: HLC-8320GPC (manufactured by Tosoh Corporation)
Detector; RI
Detection sensitivity: 3 mV / min Sampling pitch: 600 msec
Column: 4 TSKgel superHZM-N (6 mm ID × 15 cm) (manufactured by Tosoh Corporation)
Solvent: THF
Flow rate; 0.6 mm / min Concentration; 0.5 mg / mL
Column temperature: 40 ° C
Injection volume: 20 μL

(Peak temperature and peak height of loss tangent (tan δ) of block copolymer)
The dynamic viscoelastic spectrum was measured by the following method to determine the peak temperature and peak height of loss tangent (tan δ). Torsion type geometry of device ARES (trade name, manufactured by TI Instruments Inc.), sample thickness 2mm, width 10mm, length 20mm, strain (initial strain) 0.5%, frequency 1Hz, measurement range The measurement was performed from −100 ° C. to 100 ° C. under conditions of a temperature increase rate of 3 ° C./min.

<Asphalt composition>
[Production of hydrogenation catalyst]
Into a reaction vessel purged with nitrogen, 1 L of dried and purified cyclohexane was added, 100 mmol of bis (cyclopentadienyl) titanium dichloride was added, and an n-hexane solution containing 200 mmol of trimethylaluminum was added with sufficient stirring. A hydrogenation catalyst was produced by reacting at room temperature for about 3 days.

<Production of block copolymer 1>
Polymerization was performed by the following method using a stirrer having an internal volume of 100 L and a tank reactor with a jacket.
(First stage)
After charging 44.4 kg of cyclohexane into the reactor and adjusting the temperature to 60 ° C., 880 g of styrene as a monomer was added over about 3 minutes, and then 37.3 mL of n-butyllithium, N, N, N ′, N ′. -The reaction was started by adding 3.47 mL of tetramethylethylenediamine (hereinafter referred to as TMEDA).
(Second stage)
Next, 3 minutes after the maximum temperature in the reactor was reached, 1520 g of styrene was continuously fed to the reactor at a constant rate over 2 minutes, and then 1520 g of butadiene was continuously fed at a constant rate over 6 minutes. After 0.5 minutes had elapsed after being fed to the reactor, 3360 g of butadiene was continuously fed to the reactor at a constant rate over 22 minutes to cause reaction.
(3rd stage)
Thereafter, after the temperature of the reactor reached the maximum temperature, 5 minutes later, 720 g of styrene as a monomer was further added over about 1 minute and held for 5 minutes. Thereafter, 4.29 ml of an amide-containing terminator (1.3-dimethyl-2-imidazolidinone) was added and allowed to react for 10 minutes. Next, after completion of the reaction, 1.9 mL of methanol was added to obtain a block copolymer.
(Hydrogenation process)
Thereafter, using the hydrogenation catalyst, the obtained block copolymer was continuously hydrogenated at 80 ° C. to obtain a block copolymer 1. At that time, 80% by weight of the total amount of the block copolymer is continuously fed from the top of the reactor, 20% by weight of the total amount is continuously fed from the middle of the reactor, and the whole amount is continuously fed from the bottom of the reactor. Extracted. Moreover, hydrogen was continuously supplied from the lower part of the reactor separately from the outlet of the block copolymer. The hydrogen pressure in the hydrogenation polymerization vessel was 1.2 MPa, and the average residence time was 60 minutes.
After completion of the hydrogenation step, 0.25 parts by mass of stabilizer (octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate) is added to 100 parts by mass of block copolymer 1. Added.
The content of the vinyl aromatic monomer unit contained in the block copolymer 1 is 39% by mass, the content of the polymer block mainly composed of the vinyl aromatic monomer unit is 20% by mass, The average vinyl content in the conjugated diene monomer unit before hydrogenation was 30 mol%, the hydrogenation rate was 60 mol%, and the weight average molecular weight (Mw) was 210,000. The peak temperature of loss tangent (tan δ) determined by dynamic viscoelasticity measurement of block copolymer 1 was −43 ° C., and the tan δ peak height was 0.97.
The structure and composition of the block copolymer 1 were as follows.
S—B—S—Z: 100% by mass, Mw = 210,000 (wherein S represents a styrene block, B represents a random block of partially hydrogenated butadiene and styrene, and Z is The residue of an amide group-containing terminator is shown below.

<Production of block copolymer 2>
Polymerization was performed by the following method using a stirrer having an internal volume of 100 L and a tank reactor with a jacket.
(First stage)
After charging 44.4 kg of cyclohexane to the reactor and adjusting the temperature to 60 ° C., 1600 g of styrene was added as a monomer over about 3 minutes, and then 48.5 mL of n-butyllithium, N, N, N ′, N ′. -The reaction was started by adding 8.59 mL of tetramethylethylenediamine (hereinafter referred to as TMEDA).
(Second stage)
Next, 3 minutes after the temperature in the reactor reached the maximum value, 1760 g of styrene was continuously supplied to the reactor at a constant rate over 2 minutes, and then 1760 g of butadiene was continuously supplied at a constant rate over 6 minutes. After the lapse of 0.5 minutes after feeding into the reactor, 2880 g of butadiene was continuously fed to the reactor at a constant rate over 22 minutes to cause reaction.
(Stop reaction)
Then, after the temperature of the reactor reached the maximum temperature, after 5 minutes, 9.71 ml of 1.3-bis (N, N′-diurisidylaminomethyl) cyclohexane was added and reacted for 10 minutes. Next, 1.2 mL of methanol was added after completion of the reaction to obtain a block copolymer.
(Hydrogenation process)
Thereafter, using the hydrogenation catalyst, the obtained block copolymer was continuously hydrogenated at 80 ° C. to obtain a block copolymer 2. At that time, 80% by weight of the total amount of the block copolymer is continuously fed from the top of the reactor, 20% by weight of the total amount is continuously fed from the middle of the reactor, and the whole amount is continuously fed from the bottom of the reactor. Extracted. Moreover, hydrogen was continuously supplied from the lower part of the reactor separately from the outlet of the block copolymer. The hydrogen pressure in the hydrogenation polymerization vessel was 1.2 MPa, and the average residence time was 60 minutes.
After completion of the hydrogenation step, 0.25 parts by mass of stabilizer (octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate) is added to 100 parts by mass of block copolymer 2. Added.
The content of the vinyl aromatic monomer unit contained in the block copolymer 2 is 42% by mass, and the content of the polymer block mainly composed of the vinyl aromatic monomer unit is 19% by mass, The average vinyl content in the conjugated diene monomer unit before hydrogenation was 31 mol%, and the hydrogenation rate was 60 mol%. The peak temperature of loss tangent (tan δ) measured by dynamic viscoelasticity of block copolymer 2 was −33 ° C., and the tan δ peak height was 0.6.
The structure and composition of the block copolymer 2 were as follows.
(SB): 26 mass%, Mw = 121,000 (SB) _2- X + (SB) _3- X + (SB) _4- X: 74 mass%, Mw = 40.0 In the formula, S represents a styrene block, B represents a random block of butadiene and styrene that have been partially hydrogenated, and X represents a residue of a coupling agent. The same shall apply hereinafter. )Met.

<Manufacture of block copolymer 3>
Polymerization was performed by the following method using a stirrer having an internal volume of 100 L and a tank reactor with a jacket.
(First stage)
After 44.8 kg of cyclohexane was charged to the reactor and adjusted to a temperature of 60 ° C., 880 g of styrene was added as a monomer over about 3 minutes, and then 28.4 mL of n-butyllithium, N, N, N ′, N ′. -6 mL of tetramethylethylenediamine (hereinafter referred to as TMEDA) was added to initiate the reaction.
(Second stage)
Next, 3 minutes after the temperature in the reactor reached the maximum value, 1792 g of styrene was continuously fed to the reactor at a constant rate over 2 minutes, and then 2048 g of butadiene was continuously fed at a constant rate over 6 minutes. After 0.5 minutes had elapsed after being fed to the reactor, 2560 g of butadiene was continuously fed to the reactor at a constant rate over 22 minutes to cause reaction.
(3rd stage)
Thereafter, after the temperature of the reactor reached the maximum temperature, 5 minutes later, 720 g of styrene as a monomer was further added over about 1 minute and held for 5 minutes. Thereafter, 2.3 mL of methanol was added to obtain a block copolymer.
(Hydrogenation process)
Thereafter, using the hydrogenation catalyst, the obtained block copolymer was continuously hydrogenated at 80 ° C. to obtain a block copolymer 3. At that time, 80% by weight of the total amount of the block copolymer is continuously fed from the top of the reactor, 20% by weight of the total amount is continuously fed from the middle of the reactor, and the whole amount is continuously fed from the bottom of the reactor. Extracted. Moreover, hydrogen was continuously supplied from the lower part of the reactor separately from the outlet of the block copolymer. The hydrogen pressure in the hydrogenation polymerization vessel was 1.2 MPa, and the average residence time was 60 minutes.
After completion of the hydrogenation step, 0.25 parts by mass of stabilizer (octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate) is added to 100 parts by mass of block copolymer 3. Added.
The content of the vinyl aromatic monomer unit contained in the block copolymer 3 is 41.5% by mass, and the content of the polymer block mainly composed of the vinyl aromatic monomer unit is 19.5% by mass. The average vinyl content in the conjugated diene monomer unit before hydrogenation was 30 mol%, the hydrogenation rate was 61 mol%, and the weight average molecular weight (Mw) was 250,000. The peak temperature of loss tangent (tan δ) measured by dynamic viscoelasticity of block copolymer 3 was −42 ° C., and the tan δ peak height was 0.92.
The structure and composition of the block copolymer were as follows.
S—B—S: 100% by mass, Mw = 250,000 (wherein S represents a styrene block, B represents a random block of butadiene and styrene that have been partially hydrogenated. The same shall apply hereinafter.) .)

<Production of block copolymer 4>
Polymerization was performed by the following method using a stirrer having an internal volume of 100 L and a tank reactor with a jacket.
(First stage)
After 44.8 kg of cyclohexane was charged to the reactor and adjusted to a temperature of 60 ° C., 880 g of styrene was added as a monomer over about 3 minutes, and then 28.4 mL of n-butyllithium, N, N, N ′, N ′. -6 mL of tetramethylethylenediamine (hereinafter referred to as TMEDA) was added to initiate the reaction.
(Second stage)
Next, 3 minutes after the temperature in the reactor reached the maximum value, 1792 g of styrene was continuously fed to the reactor at a constant rate over 2 minutes, and then 2048 g of butadiene was continuously fed at a constant rate over 6 minutes. After 0.5 minutes had elapsed after being fed to the reactor, 2560 g of butadiene was continuously fed to the reactor at a constant rate over 22 minutes to cause reaction.
(3rd stage)
Thereafter, after the temperature of the reactor reached the maximum temperature, 5 minutes later, 720 g of styrene as a monomer was further added over about 1 minute and held for 5 minutes. Thereafter, 2.3 mL of methanol was added to obtain a block copolymer.
(Hydrogenation process)
Thereafter, using the hydrogenation catalyst, the obtained block copolymer was continuously hydrogenated at 80 ° C. to obtain a block copolymer 4. At that time, 80% by weight of the total amount of the block copolymer is continuously fed from the top of the reactor, 20% by weight of the total amount is continuously fed from the middle of the reactor, and the whole amount is continuously fed from the bottom of the reactor. Extracted. Moreover, hydrogen was continuously supplied from the lower part of the reactor separately from the outlet of the block copolymer. The hydrogen pressure in the hydrogenation polymerization vessel was 1.2 MPa, and the average residence time was 80 minutes.
After completion of the hydrogenation step, 0.25 parts by mass of stabilizer (octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate) is added to 100 parts by mass of block copolymer 4. Added.
The content of the vinyl aromatic monomer unit contained in the block copolymer 4 is 41% by mass, and the content of the polymer block mainly composed of the vinyl aromatic monomer unit is 19% by mass, The average vinyl content in the conjugated diene monomer unit before hydrogenation was 29 mol%, the hydrogenation rate was 93 mol%, and the weight average molecular weight (Mw) was 250,000. The peak temperature of loss tangent (tan δ) measured by dynamic viscoelasticity of block copolymer 4 was −33 ° C., and the tan δ peak height was 0.99.
The structure and composition of the block copolymer were as follows.
S—B—S: 100% by mass, Mw = 250,000 (wherein S represents a styrene block, B represents a random block of butadiene and styrene that have been partially hydrogenated. Hereinafter, the same applies. To do.)

<Manufacture of block copolymer 5>
Polymerization was performed by the following method using a stirrer having an internal volume of 100 L and a tank reactor with a jacket.
(First stage)
After 44.8 kg of cyclohexane was charged to the reactor and adjusted to a temperature of 60 ° C., 880 g of styrene was added as a monomer over about 3 minutes, and then 28.4 mL of n-butyllithium, N, N, N ′, N ′. -6 mL of tetramethylethylenediamine (hereinafter referred to as TMEDA) was added to initiate the reaction.
(Second stage)
Next, 3 minutes after the temperature in the reactor reached the maximum value, 1792 g of styrene was continuously fed to the reactor at a constant rate over 2 minutes, and then 2048 g of butadiene was continuously fed at a constant rate over 6 minutes. After 0.5 minutes had elapsed after being fed to the reactor, 2560 g of butadiene was continuously fed to the reactor at a constant rate over 22 minutes to cause reaction.
(3rd stage)
Thereafter, after the temperature of the reactor reached the maximum temperature, 5 minutes later, 720 g of styrene as a monomer was further added over about 1 minute and held for 5 minutes. Thereafter, 2.3 mL of methanol was added to obtain a block copolymer.
After the polymerization step, 0.25 parts by mass of stabilizer (octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate) is added to 100 parts by mass of block copolymer 5. did.
The content of the vinyl aromatic monomer unit contained in the block copolymer 5 is 42% by mass, and the content of the polymer block mainly composed of the vinyl aromatic monomer unit is 20% by mass, The average vinyl content in the conjugated diene monomer unit was 33 mol%, and the weight average molecular weight (Mw) was 240,000. The block copolymer 5 had a loss tangent (tan δ) peak temperature of −55 ° C. and a tan δ peak height of 0.91 as measured by dynamic viscoelasticity.
The structure and composition of the block copolymer were as follows.
S—B—S: 100% by mass, Mw = 240,000 (wherein S represents a styrene block, B represents a random block of butadiene that has been partially hydrogenated, and styrene. Hereinafter, the same shall apply) To do.)

[Examples 1-6 and Comparative Examples 1-9]
<Preparation of asphalt composition>
500 g of asphalt (straight asphalt 60-80 (manufactured by Shin Nippon Oil Co., Ltd.)) was introduced into a 750 mL metal can, and the metal can was sufficiently immersed in an oil bath at 180 ° C. Next, Each block copolymer or SBS was added in a small amount while stirring at the ratio shown in Table 1. After completely charging each material, the mixture was stirred for 60 minutes at a rotational speed of 3000 rpm, and then sulfur and / or a sulfur compound. The polyphosphoric acid was added little by little with stirring, and after each material was completely added, the mixture was stirred for 60 minutes at a rotational speed of 3000 rpm to prepare an asphalt composition. Tables 1 and 2 show the evaluation results of the measured asphalt compositions.

In addition, the following were used as SBS.
Block copolymer (SBS): D1101 (non-hydrogenated block copolymer, manufactured by Kraton, polystyrene block content 30% by mass, diblock content 12% by mass)
Sulfur used fine powder sulfur 200 mesh.
The polyphosphoric acid which is a cross-linking agent was manufactured by SIGMA ALDRICH.

<Preparation of modified asphalt mixture>
94.3 parts by mass of crushed stone mastic asphalt aggregates having the particle sizes shown in Table 3 below were charged into a mixer having a capacity of 27 liters equipped with a heating device, and kneaded for 25 seconds.
Next, 5.7 parts by mass of the asphalt compositions of each Example and Comparative Example produced by the above method were charged into the mixer and subjected to main kneading for 50 seconds to obtain an asphalt mixture. The obtained asphalt mixture was a crushed mastic asphalt type asphalt mixture. The total amount of the asphalt mixture was 10 kg, and the mixing temperature was adjusted to 177 ° C. for both the empty kneading and the main kneading. The aggregate used was a mixture of crushed stone and crushed sand produced from Iwafune-cho, Shimotsuga-gun, Tochigi Prefecture, fine sand produced from Sakae-machi, Inba-gun, Chiba Prefecture, and stone powder produced from Yamagata-machi, Sano City, Tochigi Prefecture. The particle size distribution of the aggregate used in the asphalt mixture is shown in Table 3 below. The obtained modified asphalt mixture was evaluated by the measurement method described later. The measurement results are shown in Tables 1 and 2 above.

<Evaluation method>
The asphalt composition was evaluated as follows.

(Compatibility of asphalt composition)
The compatibility of the asphalt composition was measured according to ASTM-D5976. A sample was filled in a Teflon tube having a diameter of 2 cm and a length of 15 cm, covered with aluminum foil, and allowed to stand in an oven at 163 ° C. for 48 hours. Then, it left still overnight in a freezer, the sample was extracted from the Teflon tube, and it divided into 3 equal parts, and measured the softening point of the upper part and the lower part. The smaller the difference between the measured values, the better the compatibility. A method for measuring the softening point will be described later. The evaluation criteria are as follows. In addition, if a measured value is 5 degrees C or less ((triangle | delta) or more), it can be used without a problem practically as an asphalt composition.

◎: Measurement value is 0.5 ° C or less ○: Measurement value is 2.0 ° C or less △: Measurement value is 5.0 ° C or less
X: The measured value exceeds 5.0 ° C

(High softness of asphalt composition (ring and ball method))
The softening point of the asphalt composition was measured according to JIS-K2207. When the sample is filled in the specified ring, supported horizontally in the glycerin liquid, a 3.5 g sphere is placed in the center of the sample, and the liquid temperature is increased at a rate of 5 ° C./min. Measured the temperature when touching the bottom plate of the ring base. The evaluation criteria are as follows. In addition, if a measured value is 70 degreeC or more ((triangle | delta) or more), it can use without a problem practically as an asphalt composition.

◎: Temperature is 90 ° C or higher ○: Temperature is 80 ° C or higher △: Temperature is 70 ° C or higher ×: Temperature is lower than 70 ° C

(Heat resistance stability during storage of asphalt compositions (heat aging resistance))
The asphalt composition produced as described above was used as a test specimen and allowed to stand in a gear oven set at 180 ° C. for 7 days. Measure Brookfield melt viscosity at 160 ° C before and after standing in gear oven and change rate (160 ° C melt viscosity after standing in gear oven / 160 ° C melt viscosity before standing in gear oven) Asked.
It shows that the smaller the change width of the Brookfield melt viscosity, the less the molecule is cut (viscosity) and gelation (viscosity increase) due to thermal deterioration, and the heat resistance is excellent. In addition, if a measured value (change ratio) is 0.7 or more and less than 0.8, or exceeds 1.4 and is 1.5 or less (Δ or more), it can be used practically without any problem as an asphalt composition.

◎: Change rate is 0.9 or more and 1.3 or less ○: Change rate is 0.8 or more and less than 0.9, or exceeds 1.3 and 1.4 or less △: Change rate is 0.7 or more and 0.8 Less than or more than 1.4 and 1.5 or less ×: Change ratio is less than 0.7 or exceeds 1.5

(Low melt viscosity of asphalt composition)
The melt viscosity of the asphalt composition was measured with a Brookfield viscometer at a measurement temperature of 160 ° C. The evaluation criteria are as follows. In addition, if a measured value (melt viscosity) is 700 mPa * s or less ((triangle | delta) or more), it can be used practically without a problem as an asphalt composition.

◎: Melt viscosity is 500 mPa · s or less ○: Melt viscosity is 600 mPa · s or less Δ: Melt viscosity is 700 mPa · s or less ×: Melt viscosity exceeds 700 mPa · s

(Aggregate-resistant peeling performance of asphalt composition)
No. 6 crushed stone (diameter 5 mm or more and 13 mm or less) used for the modified asphalt mixture prepared above was used. The asphalt composition melted at 180 ° C. was coated on No. 6 crushed stone and allowed to stand at room temperature for 30 minutes. Thereafter, the coated No. 6 crushed stone was placed on a slide glass and allowed to stand in a water bath at 70 ° C. for 3 hours. The peeling state of the asphalt composition coating after 3 hours was visually observed. The evaluation criteria are as follows. In addition, if it is below moderate peeling (triangle | delta) or more, it can be used practically without a problem as an asphalt composition.

◎: No peeling ○: Partial peeling △: Medium peeling ×: Most peeling

(Dynamic stability (DS) of modified asphalt mixture)
Dynamic stability (DS) was measured by a wheel tracking test using the modified asphalt mixture prepared above. The wheel tracking test was performed according to the Test Method Manual B003. A small rubber wheel loaded on a test specimen of a predetermined size is repeatedly reciprocated at a specified temperature, specified time, and specified speed, and the dynamic stability (DS) (times / mm) from the amount of deformation per unit time. Asked. It shows that the higher the dynamic stability, the better the excavation resistance. The evaluation criteria are as follows.

◎: 5000 or more ○: 2000 or more and less than 5000 Δ: 1000 or more and less than 2000 ×: less than 1000

(Dynamic Stability of Modified Asphalt Mixture (DS) / (G ^* / sin δ))
The dynamic stability (DS) is determined by the above-described measurement method, and G ^* / sin δ is obtained from the complex elastic modulus (G ^* ) and sin δ obtained by measuring the dynamic viscoelasticity with a dynamic shear rheometer, The ratio between the dynamic stability (DS) and G ^* / sin δ was determined. The measurement apparatus and measurement conditions were as follows.

・ Measuring device: ARES manufactured by Rheometric Scientific
・ Measurement conditions Measurement temperature: 60 ℃
Angular velocity: 10 rad / sec
Measurement mode: Parallel plate (diameter 50mmφ)
Sample amount: 2g

The higher this ratio, the better the balance between processability and flow resistance when making the asphalt mixture. The evaluation criteria are as follows. If the ratio of DS to G ^* / sin δ is 0.40 or more (Δ or more), it can be used as an asphalt composition without practical problems.

◎: Ratio is 0.65 or more ○: Ratio is 0.50 or more and less than 0.65 △: Ratio is 0.40 or more and less than 0.50 ×: Ratio is less than 0.40

    The asphalt composition of the present invention can be used, for example, in the fields of road pavement, roofing, asphalt waterproof sheet, sealant and the like, and can be suitably used particularly in the field of road pavement.

Claims (7)

An asphalt composition containing a block copolymer (A), a crosslinking agent (B), and an asphalt (C),
The ratio of the block copolymer (A) is 0.5 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of asphalt (C).
The ratio of the crosslinking agent (B) is 0.03 parts by mass or more and 3 parts by mass or less with respect to 100 parts by mass of asphalt (C).
The block copolymer (A) is a polymer block (a) mainly composed of a vinyl aromatic monomer unit, and a polymer block mainly composed of a conjugated diene monomer unit and a vinyl aromatic monomer unit. And (b) an asphalt composition having a hydrogenation rate of a double bond in the conjugated diene monomer unit of 10 mol% or more and 85 mol% or less. The block copolymer (A) has a structure (I) represented by the following formula (1), a structure (II) represented by the following formula (2), and a structure represented by the following formula (3) ( The asphalt composition according to claim 1, comprising at least one structure selected from the group consisting of III), wherein the double bond in the conjugated diene monomer unit in each structure is partially hydrogenated.

(P) _n -q (1)
(In the formula, p represents ab or ba, q represents a or b, n represents an integer of 1 or more, a represents the polymer block (a), b Represents the polymer block (b), provided that when q is a, p is a-b, when q is b, p is b-a, and q is present It may not be present, and when a plurality of a or b are included, the plurality of a or b may be the same as or different from each other.

(Y) _m -X (2)
(In the formula, X represents a residue of a coupling agent, Y represents (p) _n -q or q- (p) _n , m represents an integer of 1 or more, p, q, and n is the same as the formula (1).)

(Y) _k- Z (3)
(In the formula, Z represents a residue of a polymerization initiator or a stopper, Y represents (p) _n -q or q- (p) _n , k represents an integer of 1 or more, p, q and n are the same as those in the formula (1).)
  The asphalt composition according to claim 2, wherein the block copolymer (A) contains the structure (I) represented by the formula (1) and the structure (II) represented by the formula (2).   The ratio of the structure (I) represented by the formula (1) and the structure (II) represented by the formula (2) is the former / the latter (mass ratio) = 5/95 or more and 70/30 or less. The asphalt composition according to claim 3.   The asphalt composition according to any one of claims 1 to 4, wherein the block copolymer (A) contains a functional group.   A modified asphalt mixture comprising the asphalt composition according to any one of claims 1 to 5 and an aggregate.   The modified asphalt mixture according to claim 6, which is used for paving.