JP2003192901A - Modified asphalt composition for road paving - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a modified asphalt composition for road paving whose layer separation is inhibited, having a good mixing uniformity of a modifier and an asphalt. <P>SOLUTION: The modified asphalt composition for road paving containing an asphalt, a rubber and/or thermoplastic elastomer, a low molecular weight polypropylene and a mineral oil. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a modified asphalt composition for road paving.

[0002]

2. Description of the Related Art For road pavement, asphalt pavement using an asphalt mixture in which aggregates such as crushed stone having a predetermined grain size are mixed is often used. However, since the degree of softening of asphalt varies greatly depending on the temperature, a modifier is mixed into the asphalt to reduce the temperature dependence of the softening degree of asphalt, increase the softening temperature, or wear resistance. In addition, various properties of asphalt are improved by improving flow resistance. Examples of the modifier include rubbers such as styrene-butadiene rubber (SBR) and chloroprene rubber (CR), or styrene-, in order to improve wear resistance and fluidity resistance.
Thermoplastic elastomers such as butadiene block copolymer (SBS) and styrene-isoprene block copolymer (SIS) are used.

However, since the physical properties of the asphalt and the modifier (rubber or thermoplastic elastomer) are different from each other, the modified asphalt has problems of uniformity in mixing and phase separation.

Conventionally, as a measure for improving the mixing uniformity of the modified asphalt and preventing the phase separation and the change in the physical properties during storage, the combination of the modifier and the asphalt with good mutual solubility and affinity is used as an index. As a result, the combination of the modifier and the asphalt was decided based on the quality of the phase separation for the combination combination, but this method limits the flexibility of the composition design and also in terms of work. It is complicated.

From such a background, various measures have been proposed. For example, in Japanese Patent No. 2968961,
A modified asphalt for road paving using polyoxyethylene nonylphenyl ether to suppress phase separation is disclosed. Further, in Japanese Patent No. 3068079, a modified asphalt for road pavement having an excellent effect of suppressing phase separation in a high mixing region of SBS is obtained by using a compatibilizer having a specific physical property and a phase separation inhibitor together. Is disclosed. Further, Japanese Patent Publication No. 58-13098 discloses a rubber additive for asphalt modification, which comprises a specific mineral oil and a thermoplastic rubber and can be uniformly dispersed in blown asphalt easily in a short time. ing.

[0006]

However, the use of polyoxyethylene nonyl phenyl ether tends to be restricted in terms of environment and safety. In addition, it is desired to increase the compounding amount of the modifier in order to improve the durability.
However, when the compatibilizer and the phase separation inhibitor are used together, the amount of the modifier is 10
There are problems that the phase separation is not sufficiently suppressed in the region containing more than wt% and that a sufficient amount of rubber cannot be added even when mineral oil and thermoplastic rubber are used. Therefore, even with the above-mentioned technique, the phase separation between the asphalt and the modifier is not sufficiently suppressed, and further improvement in the storage stability of the modified asphalt due to the miscibility between the two and storage is desired. Japanese Patent No. 2886711 discloses the use of low molecular weight polypropylene for the purpose of increasing the low temperature viscosity of the modified asphalt and reducing the high temperature viscosity thereof. No mention is made of suppression of phase separation from the quality material and improvement of storage stability.

[0007]

SUMMARY OF THE INVENTION The present invention is directed to asphalt (A) and rubber and / or thermoplastic elastomer (B).
And low molecular weight polypropylene (C), mineral oil (D),
The present invention relates to a modified asphalt composition for road pavement, which comprises:

Further, the present invention uses the modified asphalt for road pavement containing the modified asphalt composition for road pavement of the present invention and an aggregate, and the modified asphalt composition for road pavement of the present invention. Concerning paved roads.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the modified asphalt composition for road pavement of the present invention, at least one of rubber and thermoplastic elastomer is used as a modifier to mix asphalt such as straight asphalt, low molecular weight polypropylene and mineral oil. Compared to the case where low-molecular-weight polypropylene or mineral oil is used individually for the modifier and asphalt, the synergistic effect of both allows a high blending ratio of the modifier and the mixture of the modifier and asphalt. The homogeneity is remarkably improved, the phase separation is remarkably suppressed, the physical properties are not changed, and the storage stability is excellent. This phase separation suppression mechanism improves the compatibility of the modifier and asphalt by mixing mineral oil,
While suppressing the separation of modifiers and asphaltene components in asphalt, low-molecular-weight polypropylene suppresses the separation by itself and also serves to prevent the viscosity of asphalt from decreasing due to mineral oil, and exerts a synergistic effect. Conceivable.

The low molecular weight polypropylene (C) has a weight average molecular weight of 1,000 to 40,000, a weight average molecular weight of 1,000 to 20,000, and further 2,000 to 1.
5,000, and particularly 3,000 to 5,000 are preferable from the viewpoint of suppressing phase separation and storage stability. This weight average molecular weight is determined by high temperature gel permeation chromatography (solvent:
Ortho-dichlorobenzene, standard substance: standard polystyrene 950, 4000, 9000, 50000, 9000
0) at 140 ° C.

The low molecular weight polypropylene (C) is
Softening point is 120 ℃ -180 ℃, 140 ℃ -160 ℃
Is preferable in terms of storage stability (suppression of phase separation) and workability during the production of modified asphalt.

As the low molecular weight polypropylene (C),
Liquid polypropylene, powder polypropylene, atactic polypropylene (APP) and the like are available, but powder polypropylene is preferably used. The method for producing the low molecular weight polypropylene (C) is arbitrary and is not particularly limited. For example, a method of thermally decomposing or oxidatively decomposing a high molecular weight polypropylene into a low molecular weight compound, propylene with a Ziegler catalyst or peroxidation It can be produced by a method such as direct polymerization using a substance or the like, and a method of separating a by-product in producing a high molecular weight polypropylene by solvent extraction or the like.

In the present invention, the low molecular weight polypropylene (C) is based on 100 parts by weight of asphalt (A).
0.1-10 parts by weight, more preferably 0.5-7 parts by weight, especially 1-
It is preferably used in a ratio of 5 parts by weight from the viewpoint of suppressing phase separation. The amount is preferably 0.1 parts by weight or more from the viewpoint of exhibiting the effect, and is preferably 10 parts by weight or less from the viewpoint of physical properties of the final asphalt.

Examples of the mineral oil (D) include raw material oil, process oil, industrial gasoline, industrial lubricating oil and base oil, and there are aroma oils, naphthene oils and paraffin oils, but low molecular weight polypropylene and From the viewpoint of compatibility with the above, paraffinic oil is preferable. Mineral oil (D) is based on 100 parts by weight of asphalt (A),
It is preferable to use 1 to 15 parts by weight, more preferably 2 to 10 parts by weight, and particularly 3 to 5 parts by weight from the viewpoint of improving the compatibility.

The asphalt (A) used in the present invention is a bituminous substance produced from petroleum straight asphalt, semi-blown asphalt, cutback asphalt, natural asphalt, petroleum tar, pitch or solvent deasphalting as pavement asphalt specifications. Suitable examples include asphalt produced by adding a softening agent.
The asphalt (A) content in the modified asphalt composition for road pavement of the present invention is preferably 70% by weight or more,
Especially preferred is a weight percentage or higher.

The rubber used in the present invention includes natural rubber and synthetic rubbers such as styrene-butadiene rubber, chloroprene rubber, acrylonitrile-butadiene rubber, styrene-isoprene rubber, methyl methacrylate-butadiene rubber and butadiene rubber. However, the present invention is not limited to these. In particular, styrene-butadiene rubber and styrene-isoprene rubber are preferable in terms of wear resistance and heat resistance.

The thermoplastic elastomer used in the present invention is a styrene-butadiene block copolymer, a styrene-isoprene block copolymer, an ethylene-vinyl acetate copolymer, an ethylene-ethyl acrylate copolymer, or , Acrylic acid esters, methacrylic acid esters, styrene homopolymers, and copolymers combining these. Particularly, a styrene-butadiene block copolymer and a styrene-isoprene block copolymer are preferable in terms of wear resistance and heat resistance.

The rubber and the thermoplastic elastomer (B) are
1 in total for 100 parts by weight of asphalt (A)
It is preferably used in an amount of from 25 to 25 parts by weight, more preferably from 3 to 20 parts by weight, and especially from 10 to 20 parts by weight, from the viewpoint of mixing properties and improving wear resistance and fluidity resistance.

The composition of the present invention may contain a polyalkylene glycol (including a mono- or diether form), a polyhydric alcohol, an alkanolamide, a lanolin and a lanolin derivative in order to further improve the mixing uniformity.

Various additives may be further added as long as the effects of the present invention are not impaired. The additive to be blended is not particularly limited and is appropriately selected from the commonly used additives. Specific examples of the additive include stone powder, talc,
Fillers such as calcium carbonate, slaked lime, amines, amides, phosphoric acid and other peeling inhibitors, methyl cellulose, fibrous reinforcing materials such as polyvinyl alcohol, viscosity reducing agents, viscosity improvers, softeners, antioxidants, UV absorption Agents, light stabilizers and the like.

The modified asphalt composition for road pavement of the present invention comprises, for example, heating and melting asphalt (A) (preferably 160 to 200 ° C.), rubber and / or thermoplastic elastomer (B), and low molecular weight polypropylene (C). ), Mineral oil (D), and agitating and mixing with a commonly used mixer until the respective components are uniformly dispersed.
Examples of commonly used mixers include homomixers, dissolvers, paddle mixers, ribbon mixers, screw mixers, planetary mixers, and vacuum backflow mixers.

Further, the modified asphalt for road pavement is prepared by mixing aggregates such as crushed stone, gravel, sand and slag with the above modified asphalt composition for road pavement with a pug mill mixer, a spiral flow mixer, a screw mixer or the like. Is obtained, and by paving this, a road having excellent wear resistance and fluidity can be made.

[0023]

EXAMPLES <Preparation of Modified Asphalt Composition> The components shown in Table 1 were mixed with a homomixer (TK, manufactured by Tokushu Kika Kogyo Co., Ltd.).
Put it in an auto homomixer M type) and run at 5000 rpm for 2
After mixing for a time, a modified asphalt composition was obtained. However, the asphalt used was one that was previously heated and melted at 180 ° C. with a mantle heater.

<Performance Evaluation> (1) Mixability The modified asphalt composition prepared above was magnified 400 times with an optical microscope, photographed, and the particle size was measured with a ruler. Then, the mixing degree of the asphalt and the rubber / thermoplastic elastomer was evaluated by the size of the mixed particles of the asphalt and the rubber / thermoplastic elastomer according to the following criteria. The results are shown in Table 1.

[Evaluation Criteria] ◯: The particle size is less than 0.5 μm and 400 with an optical microscope.
When it is doubled, it shows uniform mixing property. Δ: The particle size is 0.5 μm or more and less than 3 μm, and the particles are almost uniform, but particles are seen. X: The particle size is 3 μm or more and less than 10 μm, and the mixing property is slightly insufficient. XX: The particle size is 10 μm or more, and the mixing property is insufficient.

(2) Preservability A can having a diameter of 5 cm and a height of 11 cm was filled with the modified asphalt composition prepared above and left at 160 ° C. for 5 days, and then the center in the height direction (height 5 0.5 cm) and cut up and down, put each into a sample container and check the penetration
It was measured by the method according to 2207, and the storage stability was evaluated according to the following criteria as an index for suppressing phase separation. The results are shown in Table 1.

[Evaluation Criteria] ⊚: The difference between the upper and lower penetrability is within ± 1, which indicates good storage stability. ◯: The difference between the upper and lower penetration values is more than ± 1 and less than ± 5, and there is no problem in storage. Δ: The difference between the upper and lower penetrability was more than ± 5 and less than ± 10, and 1
It cannot be stored for more than a week. X: The difference between the upper and lower penetrability is ± 10 or more, which causes a problem in storage.

[0028]

[Table 1]

(Note) The components in Table 1 are as follows. -Asphalt: Nichireki Co., Ltd. 60-80-SBS: Styrene-butadiene block copolymer, Asahi Kasei Co., Ltd., Tuffprene 315-Low molecular weight polypropylene (1): Sanyo Kasei Co., Ltd., Viscol 550P, weight average molecular weight 4000. -Low molecular weight polypropylene (2): Sanyo Kasei Co., Ltd., Viscol 660P, weight average molecular weight 3000-Low molecular weight polypropylene (3): weight average molecular weight 30
000 ・ Mineral oil (1): Super Oil M manufactured by Nisseki Mitsubishi Corporation
32, paraffin oil / mineral oil (2): Mitsubishi Corporation Nisseki, Chrysef F22,
Naphthenic oil.

From the results shown in Table 1, it can be seen that the modified asphalt compositions obtained in Examples 1 to 5 have good mixability and excellent storability. On the other hand, the modified asphalt compositions obtained in Comparative Examples 2 and 3 have good mixability but poor storage stability, and the modified asphalt compositions obtained in Comparative Example 1 have poor mixability and can be stored. It turns out that it is also inferior in sex. Further, in Comparative Example 4 of the modified asphalt composition containing 15 parts by weight of SBS, the mixing property and the storage property are inferior, but in Example 5, there is no problem with the mixing property and the storage property.

[0031]

INDUSTRIAL APPLICABILITY According to the present invention, the asphalt and the modifier rubber or thermoplastic elastomer have a good mixing property, and the physical properties of the asphalt do not change due to storage, and the storage property becomes good.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2D051 AF01 AG01 AG03 AG04 AG15                       AH02                 4J002 AC01X AC03X AC07X AC08X                       AC09X AE05Z AG00W BB06X                       BB07X BB11Y BG04X BG05X                       BP01X GL00

Claims (5)

[Claims] 1. A modified asphalt composition for road paving, comprising asphalt (A), rubber and / or thermoplastic elastomer (B), low molecular weight polypropylene (C), and mineral oil (D). 2. The modified asphalt composition for road paving according to claim 1, wherein the low-molecular-weight polypropylene (C) has a weight average molecular weight of 1,000 to 40,000. 3. The modified asphalt composition for road pavement according to claim 1, wherein the mineral oil (D) is a paraffinic oil. 4. A modified asphalt for road paving, which comprises the modified asphalt composition for road paving according to any one of claims 1 to 3 and an aggregate. 5. A road paved with the modified asphalt composition for road paving according to any one of claims 1 to 3.