JP2001040218A - Modified asphalt composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a modified asphalt composition which is not separated, even when stored for a long time, and can be consistent with a balance with other required characteristics in a higher dimension. SOLUTION: This modified asphalt composition courprises 100 pts.wt. of asphalt, 2 to 20 pts.wt. of a high mol.wt. type thermoplastic elastomer having a number-average mol.wt. of 120,000 to 500,000, and 2 to 20 pts.wt. of a low mol.wt. type thermoplastic elastomer having a number-average mol.wt. of 80,000 to 100,000. Therein, the a high mol.wt. type thermoplastic elastomer is preferably a branched type polymer, and the low mol.wt. type thermoplastic elastomer is preferably a linear polymer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an asphalt modifier for producing modified asphalt used for road pavement and road surface treatment, a modified asphalt composition using the same, and a modified asphalt mixture.

[0002]

2. Description of the Related Art Asphalt mixtures in which aggregate is mixed with asphalt are widely used as paving materials for roads and the like. In this asphalt mixture, the pavement surface to be formed is required to have few problems such as `` ruff digging '' due to softening in the summer, `` cracking '' and `` rock jumping '' due to hardening in the winter, `` wear '', In particular, with the increase in the traffic volume of heavy vehicles in recent years and the increase in the number of vehicles equipped with chains in winter, further improvements in these performances are required.

[0003] For this reason, in recent years, rubber such as styrene-butadiene copolymer rubber (SBR) and thermoplastic elastomers such as styrene-butadiene styrene block copolymer (SBS) have been dispersed in asphalt to increase strength and strength. Modified asphalt, which is generally referred to as modified I-type or modified II-type, for increasing the viscosity has been used. Recently, high value-added pavements such as low noise and high drainage properties are becoming more widespread, and asphalt used for such pavement materials has been modified to be called a high-viscosity binder having a higher viscosity. Quality asphalt is also being used.

[0004] However, in the case of blends containing these rubbers and thermoplastic elastomers, due to differences in specific gravities and differences in SP values (solubility parameters), high temperatures at which the blends melt are caused. The rubber and thermoplastic elastomer tend to separate into the upper layer and the asphalt into the lower layer due to the static storage state of the above, which tends to make it difficult to obtain desired performance.

As means for solving these problems, (1) a method of blending mineral oil and petroleum resin to prevent the tendency to separate (Japanese Patent Laid-Open No. 6-107953), (2) a large amount of rubber and elastomer in asphalt And (3) a method of adding carbon black during stirring.

However, in the above (1) and (2), the effect cannot be improved unless a large amount of rubber, elastomer, mineral oil, or petroleum resin is blended, so that an increase in cost cannot be avoided. There is a problem in that the blending of a larger amount makes it impossible to balance the necessary properties such as penetration, softening point, toughness, viscosity and elongation. Further, in the above (3), it takes a long time to stir the asphalt in order to sufficiently disperse the carbon black. On the other hand, the carbon black precipitates in a pipe in a stirrer or the like or on the bottom of a tank. However, there was a problem in manufacturing.

In recent years, as a solution to this problem, an asphalt modifier has been proposed in which carbon black is uniformly blended into a thermoplastic elastomer to form a composite before stirring and mixing the asphalt and the thermoplastic elastomer. (JP-A-10-195301).

[0008]

According to the method described in the above-mentioned publication, it has become possible to suppress separation during storage without causing problems in production such as an increase in stirring time and adhesion due to the above-mentioned compounding of carbon black. However, penetration, softening point, toughness,
A sufficient improvement effect has not yet been obtained in terms of balancing with other necessary properties such as viscosity and elongation.

Accordingly, an object of the present invention is to provide an asphalt modifier, a modified asphalt composition and a modified asphalt composition which do not separate even after long-term storage and which can achieve a balance with other necessary properties at a high level. To provide a high quality asphalt mixture.

[0010]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that the above-mentioned object can be achieved by adopting the following constitution. Reached.

That is, the modified asphalt composition of the present invention has 2 to 20 parts by weight of a high molecular weight type thermoplastic elastomer having a number average molecular weight of 120,000 to 500,000 and 100,000 parts by weight of asphalt, and a number average molecular weight of 80,000. And 2 to 20 parts by weight of a low molecular weight type thermoplastic elastomer of あ る 100,000.

In the modified asphalt composition of the present invention, the high molecular weight type thermoplastic elastomer is a branched type polymer, and the low molecular weight type thermoplastic elastomer is a linear type polymer. It is preferable that the thermoplastic elastomer is SBS. Further, it is preferable that 1 to 15 parts by weight of oil is blended with respect to 100 parts by weight of the asphalt.

The asphalt modifier of the present invention comprises 2 to 20 parts by weight of a high molecular weight type thermoplastic elastomer having a number average molecular weight of 120,000 to 500,000 and a low molecular weight type of a number average molecular weight of 80,000 to 100,000. It is characterized in that 2 to 20 parts by weight of a thermoplastic elastomer are uniformly kneaded in advance and are made into a master batch.

Further, the modified asphalt mixture of the present invention is characterized in that the modified asphalt composition is mixed with an aggregate.

The asphalt modifier of the present invention does not separate even when stored for a long time, and achieves a high degree of balance with other necessary properties such as penetration, softening point, toughness, viscosity and elongation. Can be compatible. Therefore, a modified asphalt composition using such an asphalt modifier and a modified asphalt mixture obtained by mixing the same with an aggregate are extremely useful for road pavement and road surface treatment.

[0016]

Embodiments of the present invention will be described below. The modified asphalt composition of the present invention has a number average molecular weight of 120,000 to 500 with respect to asphalt.
000 and a low molecular weight type thermoplastic elastomer having a number average molecular weight of 80,000 to 100,000.

In the present invention, 2 to 20 parts by weight, preferably 4 to 15 parts by weight of the high molecular weight type thermoplastic elastomer and 2 to 20 parts by weight of the low molecular weight type thermoplastic elastomer are used for 100 parts by weight of asphalt. ~
20 parts by weight, preferably 4 to 15 parts by weight.

If the amount of the high molecular weight type thermoplastic elastomer is less than 2 parts by weight, the filling amount is too small to sufficiently improve the toughness and tenacity of the high molecular weight type thermoplastic resin. The balance of the total performance is lost due to a decrease in toughness, tenacity and elongation due to an increase in melt viscosity and loss of elongation.
Further, the low molecular weight type thermoplastic elastomer is 2
If the amount is less than 10 parts by weight, the filling amount is too small to improve the performance such as the separation at the time of storage by the low molecular weight type or the viscosity at 60 ° C., while if it exceeds 20 parts by weight, the melt viscosity increases. , The balance of the total performance is lost.

The above-mentioned asphalt is not particularly limited. Conventional asphalt, for example, straight asphalt, semi-blown asphalt, blown asphalt, asphalt emulsion, cutback asphalt to which tar, pitch, oil, etc. are added, regenerated asphalt, etc. Can be used. These can be used alone or in combination of two or more. Further, the asphalt may be bleached asphalt.

In the present invention, the high molecular weight type thermoplastic elastomer is preferably a branched polymer, and the low molecular weight type thermoplastic elastomer is preferably a linear type polymer.

In the high molecular weight type, the branched type is more effective in improving the mechanical performance such as toughness and tenacity by the entanglement effect of the molecular chain than the linear type, and in the low molecular weight type, When the branched type is used, the affinity with asphalt decreases, and the effect of filling the low molecular weight type is less likely to be obtained. Therefore, the linear type is preferable.

As the thermoplastic elastomer according to the present invention, styrene-butadiene-styrene block copolymer (S
BS), styrene isoprene styrene block copolymer (SIS), styrene ethylene butylene styrene block copolymer (SEBS), and the like, and one or a combination of two or more synthetic rubbers can be appropriately selected and used. Among them, SBS is particularly effective.

For improving the asphalt mechanical performance such as toughness and tenacity expected of a thermoplastic elastomer, a high molecular weight type SBS having high mechanical performance using SBS alone is effective. On the other hand, it is important to disperse asphalt as uniformly as possible for the improvement of performance such as the suppression of separation during storage and the viscosity at 60 ° C. SBS is effective. Therefore, both S
By using a combination of BS, a total balance of required performance as modified asphalt can be obtained at a high level.

In the present invention, the above asphalt 10
By blending 1 to 15 parts by weight, preferably 2 to 10 parts by weight of oil with respect to 0 parts by weight, the elongation of the modified asphalt is improved, and the performance balance is further improved.
If the amount of such oil is less than 1 part by weight, the improvement in elongation by filling with oil cannot be sufficiently obtained, while if it exceeds 15 parts by weight, it becomes too easy to elongate, and the toughness and tenacity are reduced and the elongation is reduced.
The performance balance is lost, such as a decrease in viscosity at ℃.

The type of the oil is not particularly limited.
An oil used for ordinary asphalt can be blended. Among them, among petroleum oils having three compositions of an aromatic ring, a naphthene ring and a paraffin ring, an aromatic oil having an aromatic carbon whose ring analysis result is 36% or more can be preferably used.

The modified asphalt composition of the present invention includes elastomers such as natural rubber (NR), styrene butadiene copolymer rubber (SBR), polybutadiene rubber (BR), higher fatty acid amides, higher fatty acid salts, and the like. Use polyolefins, resin compounds, inorganic compounds, antioxidants, ultraviolet absorbers, light stabilizers, anti-stripping agents, fibrous reinforcing agents, elasticity improvers, viscosity reducers, viscosity improvers, pigments, softeners, etc. as appropriate. Can be.

The asphalt modifier of the present invention comprises 2 to 20 parts by weight of a high molecular weight type thermoplastic elastomer having a number average molecular weight of 120,000 to 500,000 and a low molecular weight type of a thermoplastic elastomer having a number average molecular weight of 80,000 to 100,000. It is obtained by kneading uniformly 2 to 20 parts by weight of a thermoplastic elastomer in advance and forming a master batch.
By making a masterbatch of a high molecular weight type elastomer that requires time to dissolve in asphalt and a low molecular weight type elastomer with excellent solubility, it is possible to shorten the production time of modified asphalt and improve workability. Be improved.

[0028]

Next, the present invention will be described based on embodiments. The thermoplastic elastomers, oils and asphalts used for preparing the modified asphalt compositions of the examples and comparative examples are as follows.

Thermoplastic elastomer, high molecular weight type S
BS (Solprene 411 manufactured by Asahi Kasei) Number average molecular weight: 346000 Low molecular weight type SBS (Tufprene 125 manufactured by Asahi Kasei) Number average molecular weight: 100000 Oil (Komolex 300 manufactured by Nippon Oil Refining Co., Ltd.) Asphalt (Straight Asphalt 60/80 manufactured by Showa Shell Sekiyu Sekiyu)

According to the formulation shown in Table 1 below, T.V. K. Homomixa Mark II 20
The mixture was stirred and kneaded at 180 ° C. using a mold to prepare a modified asphalt composition.

Further, the modified asphalt composition and the aggregate were mixed at 180 ° C. using a vertical asphalt mixer.
And modified asphalt composition: aggregate = 5: 95
(Weight ratio) of a modified asphalt mixture was prepared.

The following properties of the obtained asphalt modifier, the modified asphalt composition and the modified asphalt mixture using the same were evaluated.

1. Characteristics of modified asphalt composition (1) Separation resistance performance The separation was performed according to the following procedure. 250 modified asphalts in the heated state immediately after production
Gently transfer to a ml aluminum can. The cans are left in the oven at 160 ° C. for 24 hours. At this time, seal tightly with aluminum foil to prevent scattering due to volatilization. The cans are removed, allowed to cool to room temperature, and then cut vertically through the center of the can into two semi-cylindrical states. By applying a commercially available dryer to the fractured surface of the modified asphalt composition for about one minute for any one of the semi-cylindrical objects, the lower and upper layers can be visually separated. With respect to the fractured surface subjected to the above treatment, the area ratio of the upper layer to the whole is determined in%, and is defined as the separation resistance. The higher the value, the higher the performance.

(2) Toughness Tenacity Japan Road Association, "Handbook of Pavement Test Methods" (3-5-17)
Toughness tenacity test method).
The higher the value, the higher the performance.

(3) Viscosity at 60 ° C. Japan Road Association “Handbook of Pavement Test Method” (3-5-11)
60 ° C. viscosity test method). The higher this value is, the more effective and desirable the "rubbing".

(4) Viscosity at 180 ° C. Japan Road Association “Handbook of Pavement Test Method” (3-5-10)
High-temperature kinematic viscosity test method). The lower the value, the better the handleability in the production, and thus it is desirable.

(5) Elongation at 15 ° C. Japan Road Association “Handbook of Pavement Test Method” (3-5-3)
(Elongation test method). It is desirable that this value be higher.

2. Characteristics of Modified Asphalt Mixtures Room temperature cantapro and low temperature cantapro
6)), the cantapro loss ratio (aggregate scattering resistance) at a temperature of 20 ° C. and a temperature of −10 ° C. was measured to obtain a room temperature cantapro and a low temperature cantapro, respectively.
The lower the cantapro loss rate, the higher the performance.

3. Comprehensive evaluation The target values of each performance are determined as follows, and the comprehensive evaluation of ○ which achieved all the targets and × which failed to achieve even one was performed. Separation resistance performance 80 (%) or more Toughness 200 (kgf × cm) or more Tenacity 150 (kgf × cm) or more 60 ° C viscosity 1,000,000 (poise) or more 180 ° C viscosity 700 (cSt) or less 15 ° C elongation 60 (cm) or more Room temperature cantapro 10 (%) or less Low temperature cantapro 30 (%) or less The results obtained are also shown in Table 1 below.

[0040]

[Table 1]

From the above test results, the following was confirmed. In Example 1, the target was satisfied in all of the various performances, and a good performance balance could be obtained. On the other hand, Comparative Examples 1 and 3 did not contain a low molecular weight type thermoplastic elastomer, so that the separation resistance was reduced,
In Comparative Example 2, since the high molecular weight type thermoplastic elastomer was not contained, the toughness and tenacity were not sufficiently improved. That is, in the comparative examples, none of the various performances could be improved in a well-balanced manner.

[0042]

As described above in detail, according to the present invention, the modified asphalt which does not separate even during long-term storage, and which can achieve a high-dimensional balance of all necessary properties other than separation. A composition can be obtained.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 21:00) (C08L 95/00 53:02)

Claims (6)

[Claims] 1. A high molecular weight type thermoplastic elastomer having a number average molecular weight of 120,000 to 500,000 and a low molecular weight type thermoplastic having a number average molecular weight of 80,000 to 100,000 per 100 parts by weight of asphalt. A modified asphalt composition comprising 2 to 20 parts by weight of an elastomer. 2. The modified asphalt composition according to claim 1, wherein the high molecular weight type thermoplastic elastomer is a branched polymer, and the low molecular weight type thermoplastic elastomer is a straight chain type polymer. 3. The modified asphalt composition according to claim 1, wherein the thermoplastic elastomer is a styrene butadiene styrene block copolymer. 4. With respect to 100 parts by weight of the asphalt,
The modified asphalt composition according to any one of claims 1 to 3, wherein 1 to 15 parts by weight of oil is blended. 5. A number average molecular weight of 120,000 to 5000
00 high molecular weight type thermoplastic elastomer 2
20 parts by weight and a number average molecular weight of 80,000 to 10,000
0 low molecular weight type thermoplastic elastomer 2-2
An asphalt modifier characterized by being kneaded uniformly with 0 parts by weight in advance and forming a master batch. 6. A modified asphalt mixture comprising a mixture of the modified asphalt composition according to claim 1 and an aggregate.