JPH11172111A - Modified asphalt composition for pavement - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a modified asphalt composition for pavement that is excellent in viscosity at 60 deg.C and toughbess and has excellent storage stability at elevated temperatures. SOLUTION: The asphalt that satisfies the following formulae I and II and contains 0-30 mass% o asphalt fraction and 1-100 mass% of an aromatic fraction is modified by adding at least one of rubber, a thermiplastic elastomer and a resin as a modifier where the amount of the rubber, the thermiplastic elastomer or the resin as a modifier is set to 2-40 mass% based on the total of the asphalt and each modifier. Formula I:Z1>0.4 Z1=+3.07-3.28×MN /1,000-2.19×AS/AR Formula II:Z2>0.4 Z2=+0.14-2.95×AS/AR-1.5×MW /1,000+1.37×MW/MN (MN is number-average molecular weight; MW is weight average molecular weight, As is asphalt fraction mass%, AR is aromatic fraction mass%).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a modified asphalt for pavement. More specifically, the present invention relates to a modified asphalt used for a normal pavement mixture using a dense particle mixture or a drainage pavement using an open particle mixture for asphalt pavement on a road, a sidewalk, a park, or the like.

[0002]

2. Description of the Related Art Straight asphalt and modified asphalt are mainly used as asphalt materials for road pavement. Of these, asphalt with improved performance of straight asphalt, asphalt with rubber / thermoplastic elastomer and straight asphalt with rubber or thermoplastic elastomer added to straight asphalt alone or in combination with both, as raw oil, By performing an operation of blowing air, that is, a blowing operation, the temperature sensitivity is improved, and 60 ° C.
There is a semi-blown asphalt in which the viscosity is increased from 800 to 1200 Pa · S (Pascal second). Compared with straight asphalt, modified asphalt has improved resistance to abrasion caused by heavy vehicle traffic and abrasion caused by tire chains and the like, and the asphalt mixture performance has been improved. Above all, the high-viscosity binder for drainage pavement used in open-grain mixtures that prevent water accumulation on the pavement surface in rainy weather and have a high hydroplaning reduction effect and a high noise reduction effect during high-speed running of automobiles has a flow resistance effect. As high, the viscosity at 60 ° C is 20,000 Pa · s or more, and the toughness and tenacity, which are indicators of the grasping power with the aggregate, are 20 N · m or more and 15 N · m or more, respectively. Standards are defined.

[0003]

[Problems to be solved by the invention]
Asphalt containing thermoplastic elastomer has viscosity of 60 ° C, toughness,
Although there is a modifying effect that tenacity increases, conventional asphalt containing rubber and thermoplastic elastomer,
The compatibility between the base asphalt and the modifier is not sufficient,
The reforming effect was low, the storage stability under heating was reduced, and a film was sometimes formed during storage under heating, and a satisfactory effect was not obtained.

[0004]

Means for Solving the Problems The present inventors have conducted intensive studies in order to solve the above-mentioned problems, and as a result, asphalts having a specific composition and satisfying the formula (1) or (2), The modified asphalt composition for pavement containing a specific modifier has a high viscosity of 60 ° C., which is an index of the flow resistance, and a high toughness, which is one of the indexes showing the grasping power of the aggregate. Found that the heat storage stability was high, and completed the present invention. That is, the present invention relates to asphalts satisfying the formula (1) or the formula (2) and having an asphaltene content of 0 to 30% by mass and an aromatic content of 1 to 100% by mass. At least one of a plastic elastomer and a resin is blended, and the content of the rubber, the thermoplastic elastomer, or the resin when blended is 2 to 40 of the total amount of the asphalts and the respective modifiers. It is intended to provide a modified asphalt composition for pavement, characterized in that the composition is mass%. Hereinafter, the details of the method of the present invention will be described together with the operation.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The asphalts used in the present invention are asphalts satisfying the formula (1) or (2), and the composition of the asphalts is based on the asphaltene content with respect to the total amount of the asphalts. Is 0 to 30% by mass,
Preferably it is 0 to 20% by mass and the aromatic content is 1 to 10%.
0% by mass, preferably 10 to 100% by mass. If the asphaltene content exceeds 30% by mass, the asphalt base material becomes too hard, which is not preferable in terms of low-temperature cracking and workability. Further, if the amount of the high molecular weight component such as asphaltene is too large, it is not preferable in terms of compatibility with the modifier. The Z1 and Z2 values in the formula (1) or the formula (2) of the base asphalt are 0.4.
, But preferably 0.4 <Z1 <3 and 0.4 <Z2 <5. When Z1 and Z2 are smaller than 0.4, when the modifying agent is added, the modifying agent is scattered in the asphalt in an island shape, the dispersion state of the modifying agent is reduced, the modifying effect is small, and the heating is performed. It is not preferable because a film is easily formed during storage.

[0006] The asphalts described above include, for example, straight asphalt, which is a bituminous substance obtained by subjecting various crude oils to a normal pressure distillation apparatus and a reduced pressure distillation apparatus to remove light components, and a reduced pressure when the crude oil is distilled under reduced pressure. Air is blown at a temperature of 230 to 270 ° C. under normal pressure at a pressure of 230 to 270 ° C. by distilling distillate oil, solvent deasphalted asphalt, or straight asphalt, causing dehydrogenation polymerization and condensation reaction to occur in the constituent hydrocarbons, resulting in a state of high consistency. Semi-blown asphalt and blown asphalt. Asphalts may be used alone or as 2
A combination of more than one species may be used. The composition in the above description is the result of a composition analysis test according to the Japan Petroleum Institute method (JPI-5S-22), and the number average molecular weight (MN) and the weight average molecular weight (MW) are measured by gel permeation chromatography (GPC). And calculated in terms of polystyrene.

In the formula of the present invention, not only the ratio of asphaltenes and aromatic components, but also the molecular weight, the ratio of molecular weights, or a combination of both. Therefore, the following description regarding composition and molecular weight is only a guide. MW / MN is a value serving as a measure of the molecular weight distribution, and it can be said that the larger the value, the wider the molecular weight distribution. Therefore, those having a large MW / MN may have a large amount of high molecular weight components even though the average molecular weight is small. When a large amount of the high molecular weight component is present, the state of dispersion of the modifier is reduced. The preferred range of MW / MN is 1
~ 5. AS / AR is an important measure as a dissolved component of the modifier. If the value is large, that is, if the AS amount is larger than the AR amount, the modifying material cannot be dissolved, and does not exhibit properties as modified asphalt. Further, when AS / AR is small, that is,
When the AR amount is larger than the AS amount, the effect of dissolving the modifying material is high, so that the modifying material is well dispersed. The preferred range of AS / AR is 0 to 30, more preferably 0 to 30.
5

The modifier used in the modified asphalt composition for paving of the present invention includes rubber, thermoplastic elastomer and resin. The modifier may be used alone or in combination of two or more. As the main modifying effects of these modifiers, rubber has an effect of improving elongation, thermoplastic elastomer has a viscosity of 60 ° C., and toughness and resin have an effect of improving toughness. Examples of the rubber include chloroprene rubber, styrene-butadiene rubber, natural rubber and the like, and particularly preferably styrene-butadiene rubber. As the styrene-butadiene rubber, various styrene-butadiene rubbers containing styrene at an arbitrary ratio can be used, but those having a bound styrene content of 20 to 30% by mass are preferable, and are particularly latex-like and have a solid content of 45 to 75% by mass, solid content density of 0.92 to 0.9
7 g / cm ³ is preferred. If the solid content is too small, the compounding time for compounding the required amount becomes long, and the workability decreases. Conversely, if the solids content is too high, the viscosity of the latex increases, making uniform mixing difficult. Also, when the content of bound styrene is small, the effect of increasing the viscosity at 60 ° C. tends to decrease, and when the content of bound styrene is too large, the effect of improving elongation tends to decrease. Rubber is
One type may be used alone, or two or more types may be used in combination.

The thermoplastic elastomer used in the present invention includes, for example, styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, styrene-ethylene-butadiene-styrene block copolymer, and the like. Preferably, a styrene-butadiene-styrene block copolymer is used. The styrene content of these styrene copolymers is preferably from 20 to 50% by mass, particularly preferably from 30 to 45% by mass. If the amount of styrene is too small, the effect of improving the toughness and the viscosity at 60 ° C. decreases, and if the amount of styrene is too large, the compatibility with the base asphalt tends to decrease. Further, the weight average molecular weight of this thermoplastic elastomer is 5
The range is preferably from 000 to 500,000, particularly preferably 1 to 500.
The range of 00,000 to 300,000 is preferred. If the weight average molecular weight is too small, the modifying effect is small and a large amount of compounding is required. Conversely, if the weight average molecular weight is too large, the compatibility with the base asphalt tends to decrease. The thermoplastic elastomers may be used alone or in combination of two or more.

The resin used in the present invention is preferably a petroleum resin having thermoplasticity such as an aliphatic hydrocarbon resin, an alicyclic hydrocarbon resin, or a hydrogenated hydrocarbon resin. The softening point of petroleum resins is 70 to 150 ° C, preferably 80 ° C.
１４145 ° C. If the softening point is too low, the modifying effect is small, and if the softening point is too high, the asphalt becomes too hard, which may cause problems in workability and the like.
Further, the number average molecular weight (MN) of petroleum resins is 200 to
1500, weight average molecular weight (MW) 300-3000
Is preferable, and especially MN is 300 to 1300 and MW
Is preferably in the range of 400 to 2,800. MN and MW
Is too small, the modifying effect is small, and a large amount of compounding is required. Conversely, if MN and MW are too large, the compatibility may be reduced. One type of resin may be used alone, or two or more types may be used in combination. The number average molecular weight and the weight average molecular weight of the various modifiers were measured by GPC and determined in terms of polystyrene.

The content of the modifier is 2 to 40% by mass, preferably 3 to 30% by mass, based on the total amount of asphalts and each modifier. Specifically, when rubber is compounded as a modifier, the content of rubber is 2 to 40 with respect to the total amount of asphalts and rubber.
%, Preferably 3 to 30% by mass. When a thermoplastic elastomer is blended as a modifier, the content of the thermoplastic elastomer is 2 to 4 with respect to the total amount of the asphalts and the thermoplastic elastomer.
0 mass%, preferably 3 to 30 mass%. Further, when a resin is blended as a modifier, the content of the resin is 2% of the total amount of the asphalts and the resin.
-40% by mass, preferably 3-30% by mass. When the content is less than 2% by mass, the modifying effect is reduced. When the content is more than 40% by mass, the kinematic viscosity at high temperature is increased, and the mixing property with the aggregate is reduced. Tend.

The modified asphalt composition for pavement of the present invention can be produced by mixing the above components at a predetermined ratio. The order of blending the components is not particularly limited, but it is preferable to blend the modifier in the order of resin, thermoplastic elastomer, rubber or the like after mixing the base material. Various agitators such as a propeller-type agitator and a homomixer can be used for mixing the rubber, the thermoplastic elastomer, and the like into the base material, but a homomixer that applies a high shear force is preferable. However, in the case of petroleum resin, it is not always necessary to apply a high shearing force because it is melted and mixed only by applying heat. The mixing temperature of each component is not particularly limited, but the mixing can be usually performed at 150 to 200 ° C. Also, the mixing time is not particularly limited,
Usually 5 minutes to 10 hours, preferably 1 to 1 component of modifier
0 minutes to 5 hours.

[0013] The modified asphalt composition for pavement of the present invention may, if necessary, contain other additives usually added to the modified asphalt for pavement, such as an anti-stripping agent, a dispersant and a stabilizer. . It is also possible to blend and prepare a plasticizer, for example, normal pressure residual oil, reduced pressure residual oil,
Vacuum distillation distillate, solvent deasphalted oil, base oil, aromatic oil and the like. One type of plasticizer may be used alone,
Two or more kinds may be used in combination.

Further, the method for applying the modified asphalt composition for pavement of the present invention comprises mixing the modified asphalt composition for pavement with an aggregate, a filler or the like at a predetermined temperature, laying the mixture on a pavement site, and compacting it. Can be performed. The mixing temperature with the aggregate, the filler and the like may be a normal mixing temperature, for example, 165 to 185 ° C. The rolling temperature may be a normal rolling temperature, for example, 150 to 175 ° C.

[0015]

Next, the present invention will be described more specifically with reference to examples and comparative examples. The present invention is not limited by these examples. The softening point, penetration and elongation in Examples and Comparative Examples are based on JIS K2207.
The viscosity at 60 ° C. and the toughness were determined in accordance with the Handbook of Pavement Testing Method (Japan Road Association, 1988). Heat storage stability of the modified asphalt was measured by placing about 200 g of the modified asphalt in a 350 ml aluminum can,
The film was heated for 7 days, and the surface of the surface of which the modifier was covered was designated as stability x, and the film having no or little film coverage was designated as stability ○. The composition analysis is based on the Japan Petroleum Institute method (J
PI-5S-22), the number average molecular weight (M
N) and the weight average molecular weight (MW) were measured by gel permeation chromatography (GPC), and were determined in terms of polystyrene. The GPC measurement was performed using a TSKgel Super HM-N column with tetrahydrofuran (THF) as a mobile phase using an apparatus of TOSOOH HLC-8120.

Example 1 Z1 = 0.52 (number average molecular weight (M
N) 610, AS = 10.6% by mass, AR = 42.3% by mass, AS / AR = 0.25) on a styrene-butadiene-styrene block copolymer thermoplastic elastomer (SBS, styrene / Butadiene polymerization ratio: 40/60, weight average molecular weight: 150,000
0) is 6 of the total amount of straight asphalt and SBS
% By mass and using a high shear homomixer.
The mixture was mixed at 180 ° C. for 2 hours to obtain a modified asphalt composition. Table 1 shows the properties of the obtained composition.

Example 2 Z1 = 0.44 (number average molecular weight (M
N) 620, AS = 12.1 mass%, AR = 44.1 mass%, AS / AR = 0.27), a softening point of 125 ° C., a number average molecular weight (MN) of 450,
A petroleum resin having a weight average molecular weight (MW) of 720 was converted to 25% by mass of the total amount of the straight asphalt and the petroleum resin.
Styrene-butadiene-styrene block copolymer thermoplastic elastomer (SB
S, styrene / butadiene polymerization ratio: 40/60, weight average molecular weight: 150,000) at 180 ° C. × 2 hours using a homomixer with a high shearing force of 8% by mass of the total amount of straight asphalt and SBS. After mixing, a modified asphalt composition was obtained. Table 1 shows the properties of the obtained composition.

Example 3 Z1 = 1.09 (number average molecular weight (M
N) 570, AS = 2.6% by mass, AR = 51.7%,
AS / AR = 0.05) on straight asphalt
Vacuum residue of Z1 = 0.36 (MN = 680, AS =
4.8% by mass, AR = 21.8% by mass, AS / AR =
0.22) was added at 20% of the total amount, and Z1 = 0.98 (MN = 590, AS = 3.0% by mass) satisfying the expression (1).
AR = 42.5% by mass, AS / AR = 0.07) was prepared, the softening point was 125 ° C., and the number average molecular weight (M
N) 450, a petroleum resin having a weight average molecular weight (MW) 720 of 20% by mass of the total amount of asphalt and petroleum resin,
Mix at 0 ° C. for 30 minutes and mix styrene-butadiene-
Styrene block copolymer thermoplastic elastomer (SB
S, styrene / butadiene polymerization ratio: 40/60, weight-average molecular weight: 150,000), asphalt and SBS
6% by mass of the total amount was mixed at 180 ° C. for 2 hours using a homomixer having a high shearing force to obtain a modified asphalt composition. Table 1 shows the properties of the obtained composition.

Example 4 Z2 = 1.09 (number average molecular weight (M
N) 540, weight average molecular weight (MW) 1240, AS =
4.6% by mass, AR = 46.6% by mass, AS / AR =
0.10) on straight asphalt, Z2 = 0.3
1 vacuum residue (MN = 680 MW = 2000, AS
= 8.8% by mass, AR = 33.8% by mass, AS / AR =
0.26) was added at 20% of the total amount, and Z = 0.91 (MN = 580, MW = 1380, AS =
4.8% by mass, AR = 40.8% by mass, AS / AR =
0.12) asphalt was prepared, and the softening point was 125 ° C.
Number average molecular weight (MN) 450, weight average molecular weight (MW)
No. 720 petroleum resin was mixed at 170 ° C. for 30 minutes at 20% by mass of the total amount of asphalt and petroleum resin, and a styrene-butadiene-styrene block copolymer thermoplastic elastomer (SBS, styrene / butadiene polymerization ratio: 4
0/60, weight average molecular weight: 150,000) was mixed at 180 ° C. for 2 hours using a high-shear homomixer at 8% by mass of the total amount of asphalt and SBS to obtain a modified asphalt composition. Obtained. Table 2 shows the properties of the obtained composition.

Example 5 Z2 = 0.63 (number average molecular weight (M
N) 620, weight average molecular weight (MW) 1650, AS =
9.6% by mass, AR = 46.3% by mass, AS / AR =
Styrene-butadiene-styrene block copolymer thermoplastic elastomer (SBS, styrene / butadiene polymerization ratio: 40/6)
0, weight average molecular weight: 150,000) at 180 ° C. for 2 hours using a high shear homomixer at 5% by mass of the total amount of straight asphalt and SBS,
A modified asphalt composition was obtained. Table 2 shows the properties of the obtained composition.

Example 6 Z2 = 0.91 (number average molecular weight (M
N) 620, weight average molecular weight (MW) 1630, AS =
5.2% by mass, AR = 47.9% by mass, AS / AR =
0.11) Straightening asphalt with a softening point of 125
° C, number average molecular weight (MN) 450, weight average molecular weight (M
W) 720 petroleum resins were mixed at 25% by mass of the total amount of straight asphalt and petroleum resin at 170 ° C. for 30 minutes, and styrene-butadiene-styrene block copolymer thermoplastic elastomer (SBS, styrene / butadiene polymerization ratio: 40) / 60, weight average molecular weight: 150,000
0) is 1 of the total amount of straight asphalt and SBS
0% by mass, using a high shear homomixer, 180
The mixture was mixed at a temperature of 2 ° C. for 2 hours to obtain a modified asphalt composition.
Table 2 shows the properties of the obtained composition.

Example 7 Z2 = 0.57 (number average molecular weight (M
N) 660, weight average molecular weight (MW) 1710, AS =
7.3% by mass, AR = 44.7% by mass, AS / AR =
0.16) straight asphalt with a softening point of 125
° C, number average molecular weight (MN) 450, weight average molecular weight (M
W) 720 petroleum resins were mixed at 170 ° C. for 30 minutes at 10% by mass of the total amount of straight asphalt and petroleum resin, and styrene-butadiene-styrene block copolymer thermoplastic elastomer (SBS, styrene / butadiene polymerization ratio: 40) / 60, weight average molecular weight: 150,000
0) is 6 of the total amount of straight asphalt and SBS
Mass%, using a homo-mixer with high shearing force, 180 ° C
× 2 hours to obtain a modified asphalt composition. Table 2 shows the properties of the obtained composition.

Comparative Example 1 In the formula (1), Z1 = 0.20 (number average molecular weight (M
N) 680, AS = 13.2% by mass, AR = 45.2
Mass%, AS / AR = 0.29), styrene-butadiene-styrene block copolymer thermoplastic elastomer (SBS, styrene / butadiene polymerization ratio: 40/60, weight average molecular weight: 15)
0,000) with 6% by mass of the total amount of straight asphalt and SBS using a high shear homomixer.
The mixture was mixed at 180 ° C. for 2 hours to obtain a modified asphalt composition. Table 1 shows the properties of the obtained composition.

Comparative Example 2 In the formula (1), Z1 = −0.02 (number average molecular weight (M
N) 710, AS = 15.7% by mass, AR = 45.4% by mass, AS / AR = 0.35), softening point 125 ° C., number average molecular weight (MN) 45
0, 25 mass% of the total amount of petroleum resin having a weight average molecular weight (MW) of 720
The mixture was mixed at 70 ° C. for 30 minutes to form a styrene-butadiene-styrene block copolymer thermoplastic elastomer (S
BS, styrene / butadiene polymerization ratio: 40/60, weight average molecular weight: 150,000) at 180 ° C. for 2 hours using a homomixer with a high shearing force of 8% by mass of the total amount of straight asphalt and SBS. After mixing, a modified asphalt composition was obtained. Table 1 shows the properties of the obtained composition.

Comparative Example 3 In the formula (2), Z2 = 0.18 (number average molecular weight (M
N) 770, weight average molecular weight (MW) 2240, AS =
8.4% by mass, AR = 49.8% by mass, AS / AR =
0.17) to a soft asphalt of 1
A petroleum resin having a number average molecular weight (MN) of 450 and a weight average molecular weight (MW) of 720 was mixed at 5% by mass of the total amount of straight asphalt and petroleum resin at 170 ° C. for 30 minutes at 25 ° C., and a styrene-butadiene-styrene block was obtained. Copolymer thermoplastic elastomer (SBS, styrene / butadiene polymerization ratio: 40/60, weight average molecular weight: 150,
000) to 6% by mass of the total amount of straight asphalt and SBS using a high-shear homomixer.
The mixture was mixed at 0 ° C. × 2 hours to obtain a modified asphalt composition. Table 2 shows the properties of the obtained composition.

Comparative Example 4 In the formula (2), Z2 = 0.23 (number average molecular weight (M
N) 850, weight average molecular weight (MW) 2370, AS =
1.3% by mass, AR = 48.0% by mass, AS / AR =
0.03) to a soft asphalt of 1
A petroleum resin having a number average molecular weight (MN) of 450 and a weight average molecular weight (MW) of 720 was mixed at 25 ° C, 20% by mass of the total amount of the straight asphalt and the petroleum resin at 170 ° C for 30 minutes, and a styrene-butadiene-styrene block was obtained. Copolymer thermoplastic elastomer (SBS, styrene / butadiene polymerization ratio: 40/60, weight average molecular weight: 15
000) using 8% by mass of the total amount of straight asphalt and SBS using a high shear homomixer.
The mixture was mixed at 180 ° C. for 2 hours to obtain a modified asphalt composition. Table 2 shows the properties of the obtained composition.

[0027]

[Table 1]

[0028]

[Table 2]

In Example 1, SBS was used as a modifying material in 6 parts.
In Example 1 and Comparative Example 1 in which the mass% was mixed, Example 1 which satisfied the Z1 value of 0.4 or more in the formula (1) of the base asphalt had a good dispersion state of SBS, No filming was observed. The effect of modifying the viscosity at 60 ° C., toughness and softening point as properties of the modifying effect is also large. On the other hand, Comparative Example 1, which does not satisfy the Z1 value of 0.4 or more in the formula (1) of the base asphalt,
The dispersion state of the BS was poor, film sticking was observed during storage under heating, and the reforming effect was not obtained as in Example 1. 8% by mass of SBS and 25 of petroleum resin as modifiers
In Example 2 and Comparative Example 2 in which the mass% was mixed, Example 2 which satisfied the Z1 value of 0.4 or more in the formula (1) of the base asphalt had a good dispersion state of SBS, No film tension was observed, and the effect of modifying the softening point, toughness, and viscosity at 60 ° C. was greater than that of Comparative Example 2.

Z satisfying the Z1 value of 0.4 or more in equation (1)
For Example 3 in which one value is 0.653, SBS6
Since the modifying effect was not obtained only by 20% by mass and 20% by mass of petroleum resin, 20% by mass of a vacuum residue oil was blended as a plasticizer. In Example 3, the dispersion state of SBS was the most excellent, the viscosity was high at 60 ° C., and no film sticking was observed during heating and storage. According to the first aspect of the present invention, as an index for explaining asphalts, in addition to the molecular weight, an index of AS / AR is used. As a result, the coefficient of determination of the multivariate analysis is 0.82 in a regression equation using only the molecular weight. From 0.92 to 0.92.
This is because not only the molecular weight but also the ratio of the aromatic component as the dissolving component of the asphalt composition and the asphaltene component as the dissolution inhibiting component in the asphalt composition contribute to the asphalt modifying effect and the heat storage stability. It seems to be because.

According to the second aspect of the present invention, MN, MW, MW / MN, AS / A are used as indices for explaining asphalts.
The index of R was used. The coefficient of determination of the multivariate analysis is also 0.
It rose to 94. This means that the molecular weight distribution is wider as the value of MW / MN, that is, the value that is a measure of the molecular weight distribution, is larger. However, those with a higher value of MW / MN have more high molecular weight components even though the average molecular weight is smaller. If there is a possibility that a high molecular weight component is present in a large amount, the state of dispersion of the modifier is reduced. For this purpose, the coefficient of determination was improved by incorporating the molecular weight ratio, that is, the molecular weight distribution, into the formula. In particular, in the asphalt shown in Comparative Example 6, A
It shows a very small value of S / AR = 0.03, and although there are many dissolved components of the modifying material and few dissolution inhibiting components,
It is considered that the storage stability and the modification effect are inferior to those of Examples 4 to 7 due to the molecular weight and molecular weight distribution.

From the above, it can be said that Examples 1 to 7 of the present invention are effective as a modified asphalt composition for pavement.
In the present invention, the average molecular weight of the asphalt as the base of the modified asphalt is small to some extent, and the less the high molecular weight component, the better the dispersibility of the modifying material, the greater the modifying effect, and the more the modifying material Is based on the finding that the modifying effect differs depending on the ratio of the aromatic component as a dissolution component to asphaltene as a dissolution inhibiting component. For example, considering that the mixture of SBS and asphalt is formed by asphalt molecules entering into the polymer chains of SBS and entangled, asphalts having a small molecular weight can easily mix with the polymer chains. It is considered that asphalts having a large molecular weight or asphalts having a high molecular weight component have a low compatibility because the high molecular weight component sterically hinders mixing with such a polymer chain. Furthermore, even if there is a large amount of asphaltene as a dissolution inhibiting component, the addition of a plasticizer can change the composition of asphalts and improve the solubility of the modifier.

[0033]

The modified asphalt composition for pavement of the present invention has a good compatibility between the base asphalts and the modifying material, and a viscosity at 60 ° C. which is considered to have a high correlation with the asphalt pavement resistance to rutting. And excellent toughness, which is an index of the adhesion between the asphalt binder and the aggregate and the bonding strength between the binders, and is excellent in the heat storage stability. Therefore, the modified asphalt composition for paving of the present invention is extremely useful in practice.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kiyomi Takagi 1134-2 Gongendo, Satte City, Saitama Prefecture, Cosmo Research Institute R & D Center

Claims (2)

[Claims] 1. Asphalts satisfying the formula (1) and having an asphaltene content of 0 to 30% by mass and an aromatic content of 1 to 100% by mass as rubber, thermoplastic elastomer and resin as modifiers. At least one of them is compounded, and the rubber, thermoplastic elastomer, or resin content when compounded is 2 to 40% by mass of the total amount of asphalts and each of the modifiers. Characteristic modified asphalt composition for pavement. (1) Z1 = + 3.07−3.28 × MN / 1000−2.1
9 × AS / AR (wherein, MN represents number average molecular weight, AS represents asphalten mass%, and AR represents aromatic mass%). 2. Asphalts satisfying the formula (2) and having an asphaltene content of 0 to 30% by mass and an aromatic content of 1 to 100% by mass are used as modifiers for rubbers, thermoplastic elastomers and resins. At least one of them is compounded, and the rubber, thermoplastic elastomer, or resin content when compounded is 2 to 40% by mass of the total amount of asphalts and each of the modifiers. Characteristic modified asphalt composition for pavement. ## EQU2 ## Z2> 0.4 (2) Z2 = + 0.14-2.95 × AS / AR-1.54 ×
MW / 1000 + 1.37 × MW / MN (where, MN is a number average molecular weight, MW is a weight average molecular weight,
AS indicates asphalten mass%, and AR indicates aromatic mass%. )