JP2892998B2 - Modified asphalt and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a modified asphalt mainly used for road pavement and a method for producing the same.

More specifically, the present invention relates to a modified asphalt having improved asphalt flow resistance and improved toughness and tenacity, and a method for producing the same.

[0003]

2. Description of the Related Art Asphalt pavement is manufactured by mixing a mixture of crushed stone, sand and the like having an appropriate particle size distribution, as a binder, generally with a straight asphalt having a penetration of 40 to 100 in a heated state. It is constructed by spreading a so-called asphalt mixture and rolling with rollers.

[0004] In recent years, however, the use of asphalt-paved roads has become quite severe due to the increase in traffic, especially for heavy vehicles. Especially in the summer season, the rutting phenomenon due to the flow on the asphalt-paved road surface frequently occurs. Rutting on asphalt pavement not only impairs the riding comfort of the car, but also reduces the operability of the steering wheel, and water accumulation during rainfall on the rutting part causes slips, which is a major problem in traffic safety. ing.

[0005] As a measure against rutting, it is necessary to improve the softening point of asphalt to improve the flow resistance of pavement, and at the same time, to improve the grasping power and toughness of asphalt with respect to aggregate. Therefore, the use of so-called modified asphalt in which a modifier is added to asphalt to improve these properties is increasing.

There are toughness and tenacity as properties of asphalt relating to the performance of grasping aggregate. This can be said to be the absorbed energy up to breakage when a tensile test is performed under specified conditions, and it can be said that the larger this value is, the better the aggregate grasping performance is. This is considered to be closely related to the adhesion and toughness of asphalt to aggregate.

In recent years, drainage pavements have been widely used for the purpose of traffic safety in rainy weather and reduction of traffic noise. The drainage pavement has a gap in the aggregate particle size and increases the porosity of the pavement to around 20%. The asphalt used in this pavement naturally requires strong aggregate grasping performance, high toughness, Modified asphalt with tenacity is used.

[0008] Modified asphalt is generally produced by mixing a reforming material with straight asphalt, which is the residual oil of vacuum distillation of crude oil. Rubber emulsions, thermoplastic resins, and the like have been used as modifiers. Rubber emulsions have a large effect of improving the low-temperature brittleness of asphalt, but have an insufficient effect of improving flow resistance. On the other hand, although a thermoplastic resin can be expected to have an effect of improving flow resistance, it has poor dispersibility in asphalt, and it is difficult to uniformly disperse it in asphalt to obtain modified asphalt. Also,
Even when a thermoplastic resin is dispersed in asphalt with sufficient temperature and mechanical action to produce a modified asphalt, phase separation of the asphalt easily occurs during storage under heating.

In order to overcome the problems described above, recently, a substance called a thermoplastic elastomer having intermediate properties between rubber and a thermoplastic resin is often used as a modifier for asphalt.

A thermoplastic elastomer is a polymer material comprising a so-called thermoplastic resin portion and an elastomer portion having rubber-like properties. A typical example is a thermoplastic resin portion comprising polystyrene and an elastomer. There is a styrene-butadiene-styrene block copolymer (SBS) in which a part is polybutadiene, or a styrene-isoprene-styrene block copolymer (SIS) in which a thermoplastic resin part is polystyrene and an elastomer part is polyisoprene.

These SBS and SIS exhibit an excellent modifying effect on asphalt as compared with rubber emulsions and the like, and their mixing and dispersibility in asphalt are improved as compared with many thermoplastic resins. ing.

[0012]

As described above, asphalt pavement is mixed with a thermoplastic elastomer as a modifier in order to improve the flow resistance and the ability to grasp aggregates and to increase the resistance to rutting. The use of modified asphalt is becoming common, but has the following problems.

Although thermoplastic elastomers are generally easier to mix with asphalt than thermoplastic resins, in order to produce a modified asphalt having sufficient flow resistance, a thermoplastic elastomer as hard as possible is required. The required amount, must be mixed into the asphalt. However, as the properties of the thermoplastic elastomer become harder and as the mixing amount increases, it becomes more difficult to uniformly mix the thermoplastic elastomer with asphalt. Therefore, it is still difficult to mix a required amount of a hard thermoplastic elastomer with a desired modifying effect into asphalt.

According to the present invention, when producing a modified asphalt, a soft modifier which is relatively easy to mix is mixed in a smaller amount as compared with the conventional method, so that the performance of the modified asphalt is equal to or higher than that of the existing modified asphalt. The present invention has been made to provide a modified asphalt having the following and a method for producing the same.

According to the present invention, when modifying asphalt with a polymer substance, a softening and a smaller amount of a polymer substance, which is easier to mix with asphalt, is used to obtain a higher modification effect than before. A high quality asphalt and a method for producing the same are provided.

[0016]

Means for Solving the Problems The above problems are: 1. Modified asphalt obtained by reacting a mixture of asphalt and SIS with sulfur; 2. Modified asphalt containing a reaction component of sulfur and SIS in asphalt; 3. The modified asphalt according to 1 or 2, wherein the SIS has a polystyrene content of 10 to 40% by weight; At a temperature of 120 ° C to 180 ° C, 0.01 to 1. 1 parts by weight of 100 parts by weight of a mixture of asphalt and SIS.
4. A method for producing a modified asphalt, which comprises adding 0 parts by weight of sulfur; 4. The method for producing modified asphalt according to 4, wherein the SIS has a polystyrene content of 10 to 40% by weight.

In particular, as a result of intensive studies, the present inventors have found that 100 parts by weight of a mixture of asphalt and SIS at a temperature of 120 ° C. to 180 ° C. and 0.01 to 1.0.
It has been found that the addition of 0 parts by weight of sulfur dramatically improves the reforming effect, and the present invention has been completed.

Further, SIS has a higher solubility in asphalt than SBS or the like, and is easy to mix.

Further, when the SIS has a polystyrene content of 10 to 40% by weight, mixing with asphalt is even easier, and the effect of the present invention is remarkably exhibited.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Asphalt used in the present invention is petroleum asphalt.
Those having a value of 0 or less are particularly preferred. These include penetration grades 40 to 60, 60 to 80, and 8 specified in Japanese Industrial Standard (JIS) K2207.
0-100 straight asphalt and the like. When the penetration of asphalt is less than 40, the adhesiveness of the asphalt binder obtained is insufficient, and when the penetration exceeds 100, the effect of improving the rutting resistance is small.

The SIS used in the present invention has a property of swelling by absorbing an oil component called a saturated component or an aromatic component, which is a component of asphalt, and has a good mixing property with asphalt. Among them, polystyrene content is 10
SIS, which is 40% by weight, is particularly preferable because of this tendency.

One of the points of the present invention is that asphalt and S
The addition of sulfur to the IS mixture significantly improves the reforming effect.

That is, in the case where a relatively soft modifier which does not provide a large modifying effect conventionally is used, or when a small amount of modifying agent which does not produce the modifying effect is added, Is that a sufficient modifying effect can be obtained.

The mixing ratio of asphalt and SIS is not particularly limited. However, if the standard property of the modified asphalt type II described in the “Asphalt Pavement Outline” edited by the Japan Road Association is targeted, asphalt 99-97 weight Parts by weight of SIS is sufficient.

When used as a binder for drainage pavement, the mixture ratio of SIS in the above mixture can be increased.

Sulfur is mixed with the mixture at a temperature of 120 ° C. to 180 ° C. to cause a sulfur crosslinking reaction at the unsaturated bond portion of the polymer substance. The time required for the reaction depends on the mixing temperature, but at a temperature of 150 ° C., is about 0.5 to 1 hour under stirring by a blade-type stirrer. The stirring means is not limited, and a homomixer or the like may be used.

By this reaction, the elastic properties of the polymer material are improved, the rigidity is increased, and the modifying effect is dramatically improved.

The temperature at which this sulfur crosslinking reaction takes place is
If the temperature is lower than 120 ° C., the viscosity of asphalt is too high, and it is also near the melting point of sulfur, which is not preferable. 180 ° C
If it exceeds 2,000, the polymer substance may be degraded, and the vapor pressure of sulfur increases, which is not preferable.

The amount of sulfur added is preferably 0.01 to 1.0 part by weight based on 100 parts by weight of the mixture of asphalt and SIS. If the amount of sulfur is less than 0.01 part by weight, the crosslink density is too low and the effect is small. On the other hand, if it exceeds 1.0 part by weight, the crosslinking density is too high, the brittleness increases, and the elongation decreases, which is also not preferable.

It is preferable to add powdered solid sulfur to the sulfur, but the shape of the sulfur is not particularly limited, and molten liquid sulfur can also be used.

It is not essential for the present invention to mix asphalt and SIS sufficiently uniformly before adding sulfur, but it is better to add sulfur to a system in which both are mixed to some extent evenly. It is preferable to obtain a uniform modified asphalt.

[0032]

EXAMPLES Hereinafter, the present invention will be described more specifically by reference examples, comparative examples, and examples, but the present invention is not limited to these examples.

Reference Examples 1 to 21 Penetration 68 (The measuring method is based on JIS K 2207.
The same shall apply hereinafter) of 99 to 95 parts by weight of straight asphalt and 1 to 5 parts by weight of a styrene-butadiene-styrene block copolymer (SBS) having a polystyrene content of 20% by weight in a stainless beaker at a temperature of 170 ° C. by a blade stirrer. The mixture was stirred to obtain a mixture having a different mixing ratio between asphalt and SBS.

To 100 parts by weight of each mixture, 0.1 to 0.75 parts by weight of reagent sulfur is added at a temperature of 150 ° C., and the mixture is stirred for 0.5 hour to carry out a crosslinking reaction between sulfur and SBS. Was.

The properties of the obtained modified asphalt are shown in Tables 1 to 3.
5 shows Reference Examples 1 to 21.

The properties of the modified asphalt were measured as follows:
For penetration, softening point and elongation, refer to JIS K 220
This was performed according to the method specified in 7. The toughness and tenacity were measured according to the test method described in “Handbook of Paving Tests” published by the Japan Road Association.

Comparative Example 1 Straight asphalt 99 used in Reference Examples 1 to 21
Table 1 shows the properties of the mixture of 95 parts by weight and 1 to 5 parts by weight of SBS.
5 to Comparative Examples 1 to 5.

The effects of the present invention are apparent from these reference examples and comparative examples.

For example, looking at Reference Example 1 and Comparative Example 1 in Table 1, the mixing ratio of asphalt and SBS is 99 to 1 in both cases, but the reference example has a toughness of 2.8 and a tenacity. This shows a 6.8-fold improvement.

The values of toughness 14.1 N · m and tenacity 9.6 N · m of the present reference example are higher than those of Comparative Example 5 in Table 5, and the mixing ratio of asphalt and SBS in Comparative Example 5 is Given that it is 95: 5,
That's just amazing.

Table 4 shows the case where the mixing ratio of asphalt to SBS is 97: 3. Comparing Reference Example 17 with Comparative Example 4, the reference example has a softening point of 11.5.
The increase in ° C shows a 2.2-fold increase in toughness and a 3.6-fold increase in tenacity.

It can be seen that the other reference examples also show the effectiveness of the present invention.

[0043]

[Table 1]

[0044]

[Table 2]

[0045]

[Table 3]

[0046]

[Table 4]

[0047]

[Table 5] Examples 1 to 21 In the above Reference Examples 1 to 21, as a result of conducting an experiment only by replacing SBS with SIS,
An effect equivalent to 21 was observed.

[0048]

As described above, the present invention has the following excellent effects in producing modified asphalt.

(1) When modifying asphalt using SIS as a modifier, the modifying effect is drastically improved even if the properties of the polymer material of the modifier are too soft and the modifying effect is small. Can be done.

(2) When modifying asphalt using SIS as a modifying material, the present invention can improve the modifying effect even when the amount of the polymer substance of the modifying material is small and the modifying effect is small. Dramatic improvement can be achieved, and at the same time, raw material costs can be reduced.

(3) In the case where the properties of the above-mentioned modified polymer material are soft and the amount of the polymer material of the modifying material is small, mixing of asphalt and the modifying polymer material is easy in both cases. In the production of modified asphalt, the ratio of mixing equipment and production conditions are greatly reduced.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Yoshiro Hirasawa 628, Suenaga, Takatsu-ku, Kawasaki City, Kanagawa Prefecture 311 Avniru Mizochi 311 JP, A) JP 43-3120 (JP, B1) JP 7-500141 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C08L 95/00 C08L 25/08 C08L 53/02

Claims (5)

(57) [Claims] 1. A modified asphalt obtained by reacting a mixture of asphalt and a styrene-isoprene-styrene block copolymer (SIS) with sulfur. 2. A modified asphalt containing asphalt a reaction component of sulfur and a styrene-isoprene-styrene block copolymer (SIS). 3. The modified asphalt according to claim 1, wherein the SIS has a polystyrene content of 10 to 40% by weight. 4. At a temperature of 120 ° C. to 1800 ° C., 100 parts by weight of a mixture of asphalt and SIS is 0.1%.
A method for producing a modified asphalt, comprising adding 01 to 1.0 part by weight of sulfur. 5. The method for producing a modified asphalt according to claim 4, wherein the SIS has a polystyrene content of 10 to 40% by weight.