JPH0374464A - Asphalt composition - Google Patents

Abstract

PURPOSE:To obtain a composition excellent in resistance to rut and flow, etc., and also in applicability, thus suitable for road paving by incorporating asphalt with a specified amount of a styrene-butadiene copolymer prepared by polymerization using a specific molecular weight regulator so as to get extremely broad in molecular weight distribution. CONSTITUTION:The objective composition can be obtained by incorporating (A) 100 pts.wt. of asphalt with (B) 1-10 pts.wt. of a styrene-butadiene copolymer 10-35wt.% in the content of bound styrene, 50-140 in Mooney viscosity, containing >=15wt.% of a component <=4.5X10<4> in molecular weight and >=30wt.% of a second component >=5.0X10<5> in molecular weight, and also containing >=30wt.% of a styrene-butadiene copolymer prepared by emulsion polymerization of 100 pts.wt. of a monomer using 0.05-5 pts.wt. of n-octyl mercaptan as the essential component of molecular weight regulator.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to an asphalt composition for road paving, particularly for heavy traffic road pavement, etc. The present invention provides a rubber-containing asphalt composition suitable for fields with severe demands.

(Prior art) A composition made by blending asphalt with aggregate is relatively stable, has excellent abrasion characteristics, does not require a long curing period during construction, and is inexpensive. It is widely used as a paving material for roads, etc.

However, as the viscosity of asphalt is highly temperature dependent, it tends to soften in the summer and cause ruts, and conversely hardens in the winter, causing cracks, and suffers from severe wear due to traffic such as chains. There is.

(Problem to be solved by the invention) In order to modify this, paving mixtures are used that use modified asphalt as a binder to which polymeric materials such as rubber and resin are added. In heavy traffic pavements, etc., a sufficient reforming effect is not necessarily obtained, and problems such as flow deformation phenomena such as rutting, flow, and waves, as well as wear, cracking, and peeling occur in a short period of time. Therefore, further improvements are desired.1 For example, introduction of polar groups into styrene-butadiene rubber (hereinafter abbreviated as SBR) (4? Publication No. 249142) and addition of carboxy-modified polyolefin (Japanese Patent Laid-open Publication No. 2002-249142). /!Za=!6 Publication), S
Methods such as increasing the particle size of BR (% opening/closing 1,0-2!2b'l'1 publication) and blending high Mooney SBR and low Mooney SBR (Japanese Patent Application Laid-Open No. 1998-9!F101) are available. Proposed.

In view of this situation, the present inventors have conducted intensive studies to develop a new rubber-containing asphalt composition for road paving, and as a result, have arrived at the present invention.

(Means for Solving the Problems) The present invention provides an asphalt composition that is excellent in both asphalt physical properties such as rutting resistance, flow resistance, cracking resistance, peeling resistance, etc., and workability (workability). This objective is achieved by blending SBR, which has been polymerized to extremely broad molecular weight distribution, into asphalt using a specific molecular weight regulator.

That is, the present invention contains at least 30% by weight of SBR, which is obtained by emulsion polymerization using 0.02 to 0 parts by weight of n-octyl mercaptan as a necessary component among the molecular weight regulators, and has a molecular weight as a low molecular weight component. +, j ! wt%, Mooney viscosity (ML1+4-/00'C), kO
~/! The gist of this invention is a modified asphalt prepared by blending an SBR in the range of 0 to 70 parts by weight based on ioo parts by weight of asphalt, and an asphalt pavement composition in which aggregate is blended with the modified asphalt.

In the present invention, the molecular weight and molecular weight distribution of SBR can be determined under the following conditions.

Manufactured by Toyo Soda ``GP C (HLC-goxR,)''
Column: 1 Styla Gel manufactured by WATER3 / 0
6+/05+/θ4+/θ3 Mobile phase; Tetrahydrofuran (THF) pretreatment; After dissolving the sample THFK, the sample solution is filtered through a Millibore/μm filter, and the dissolved solution is measured.

The present invention will be explained in detail below.

The asphalt used in the present invention may be any commonly used asphalt, such as straight asphalt for pavement, rake asphalt, blown asphalt, and semi-blown asphalt.

Further, the SBR used in the present invention can be obtained by one-stage polymerization using an emulsion polymerization method using a specific molecular weight regulator. Although methods such as blending a certain amount of low molecular weight components and SBRs with different polymer contents may be considered, in order to achieve the effects of the present invention, n-octyl mercaptan is used as an essential component of the molecular weight regulator. It is essential that Generally, SBR by emulsion polymerization method is widely produced industrially, but
Tertiary dodecyl mercaptan (hereinafter abbreviated as t-DM) is usually used as the molecular weight regulator. This is because it has a long life as a molecular weight regulator during polymerization and can accurately control Mooney viscosity with a small i.

In this case, the molecular weight distribution is relatively sharp and the molecular chains are also linear.

When SBR produced by this ordinary polymerization method is applied as an asphalt modifier, the physical properties of asphalt and workability (workability) are in a trade-off relationship. In other words, if the Mooney viscosity of SBR is increased, the physical properties of asphalt such as the ability of the rubber to grip the asphalt aggregate (hereinafter referred to as "toughness") and the adhesive strength to aggregate (hereinafter referred to as "tenacity") will improve. , The asphalt viscosity is high at high temperatures, which deteriorates the workability.

On the other hand, if the Mooney viscosity of SBR is reduced, workability is improved, but improvements in asphalt physical properties such as toughness and tenacity are insufficient.

On the other hand, when the n-octyl mercaptan of the present invention is used as a molecular weight regulator and SBR with an extremely wide molecular weight distribution having a certain amount or more of low molecular weight components and high molecular weight components is blended into asphalt, surprisingly, the construction It was found that asphalt physical properties such as toughness and tenacity can be significantly improved while keeping high-temperature viscosity, which is an index of properties, low.

In addition, as a method of obtaining SBR with a wide molecular weight distribution having a certain amount or more of low molecular weight components and high molecular weight components, there is a method such as blending high Mooney viscosity SBR and low Mooney viscosity SBR that have extremely different average molecular weights (Mooney viscosity). is also considered, but in this case, t-DM as a molecular weight regulator
Even if ordinary SBRs using the above were blended together, the balance between asphalt performance and workability simply moved on the formability line of these SBRs, and little improvement effect was observed. That is, in order to realize the effects of the present invention, it is essential to use n-octyl mercaptan as an essential component of the molecular weight regulator.

Although it is not clear why SBR using n-octyl mercaptan behaves differently from SBR using normal t-DM, it is thought to be due to the difference in reactivity of mercaptan, which is a molecular weight regulator. It will be done.

The amount of n-octyl mercaptan added is mono r
-/00 parts by weight is preferably in the range of 2.0 parts by weight of O, OSb. If it is less than 0.03 parts by weight, the effect of addition will be little, and the amount of low molecular weight components will also be below a certain level, resulting in poor asphalt workability. Furthermore, if the amount exceeds the weight parts of S and O, the amount of low molecular weight components increases too much and the asphalt performance balance becomes unbalanced. The addition method may be batch addition, divided addition, or continuous addition. Also, if the molecular weight distribution is within the above range, t-D
Other molecular weight regulators such as M may be used in combination.

Further, the SBR used in the present invention exhibits its effects by containing a certain low molecular weight component and a high molecular weight component. Specifically, molecular weight mold. ,! ;X/
0' or less component /S weight or more, and k, OX /
It is necessary to contain at least 30 weight of a component with a weight of 0'' or more.As a low molecular weight component!, & However, the workability (workability) deteriorates.Also, if the amount of high molecular weight components with OX/05 or higher is less than 30% by weight, the effect of modifying asphalt physical properties such as toughness and tenacity will not be sufficient. .

That is, the effect of the present invention can be fully exhibited only when a certain amount or more of both the low molecular weight component and the high molecular weight component are contained. As long as this range is met, SBR polymerized using n-octyl mercaptan may be blended with SBR polymerized using normal t-DM alone, but the ratio must be adjusted to achieve the desired effect. Must be less than 0% by weight.

In addition, the SBR used in the present invention has a bound styrene content of /θ~
It is necessary that the weight is less than 3s, and if it is less than 10%, it tends to gel when mixed with asphalt, and 3s!
If the amount exceeds % by weight, rubber elasticity decreases.

Mooney viscosity is ML based on asphalt physical properties and workability.
At I+4100'C! The range of o~/4I-□ must be lowered.

The SBR of the present invention can be added to asphalt in the form of latex or solid rubber, but is usually added in latex form. The amount of SBR added to asphalt varies depending on the type of asphalt used and the amount of traffic, etc., and ranges from / to io parts by weight of the SBR of the present invention in solid content relative to asphalt)/17 (7 parts by weight). .High flow resistance, wear resistance, especially for heavy traffic road pavement, etc.
When cracking resistance is required, it is preferable to add 3 to 70 parts by weight. Of course, other modifiers such as resins may be used in combination.

The asphalt pavement composition is obtained by mixing aggregates of crushed stone, sand, and stone powder with the above asphalt composition, but it can be produced by a normal manufacturing method, for example, by kneading SBR latex at the same time as asphalt and aggregates in an asphalt plant kisser. Plant mix method or SBR on asphalt in advance
It is manufactured by a premix method, etc., in which aggregate is mixed with a mixture of

The particle size and blending ratio of crushed stone, sand, and stone powder as aggregates can be appropriately selected according to the purpose of paving according to conventional methods, and the amount of asphalt composition used is generally about 3 parts by weight of the paving composition. ×/105. ! f~7J wt% is most common.

(Example) Hereinafter, the present invention will be specifically explained with reference to Examples.

[Evaluation as a 1-part binder (Examples ゛Z-DA, Comparative Example 1-DA) (Example-/) Capacity 1001 according to the basic polymerization recipe shown in Table 7
7 parts of /3-butadiene, 29 parts of styrene and 6 parts of n-octyl mercaptan as a molecular weight regulator were added to a polymerization reactor, and emulsion polymerization was carried out under the conditions of temperature &,j-'C. It started.

When the conversion rate reached sr%, diethylhydroxylamine in the O and OS parts was added to stop the reaction. Next, unreacted monomers were collected and concentrated according to a conventional method to obtain SBR latex with a solid content concentration of go%.

Strain this latex asphalt I (penetration level 6).
Q-50, Showa Shell Sekiyu Co., Ltd.) 140-170
A rubber-containing asphalt containing 3X rubber in terms of solid content was obtained.

This rubber-containing asphalt was tested for the following items. The evaluation results are shown in Table 2.

((a) Penetration Measurements were made in accordance with JISK 330.

However, the temperature is 0°C and the load is 100? , the load action time is S
Seconds.

(b) Softening point J IS K 2! Compliant with J/.

(c) Toughness and tenacity were measured by the benone method. However, the temperature was S°C, the pulling speed was θθ min/min, and the pulling amount was som.

) 60 parts viscosity Measured using a reduced pressure capillary viscometer according to JAA-OO/(JAA: Japan Asphalt Association Test Method).

(E) ibo°C, /70 parts Viscosity Measured using a BROOKFIELD type viscometer according to ASTM DJ&A9.

In Table 4, the test methods regarding the properties of rubber latex are as follows.

(a) Amount of bound styrene JIS K63! ; Measured according to the following.

(b) Mooney viscosity (MLl +4.100°C) The rubber component is recovered from the rubber latex, and the rubber is
Measured according to b3g3.

(c) Molecular weight As already mentioned.

(Example-7) The procedure of Example-7 was followed except that the amount of n-octyl mercaptan added was 0.2 parts.

(Example 3) Molecular weight modifiers were mixed with 0.3 parts of mono-octyl mercaptan and 0.06 parts of tertiary dodecyl mercaptan (t-DM).
) was used in combination with Example 7.

(Example 4) SBR latex (Mooney viscosity ML1+49 ff) polymerized according to Example 7 using 0 parts of n-octyl mercaptan as a molecular weight regulator, and 01aO
SBR polymerized using t-dodecyl mercaptan
The procedure of Example 1 was followed except that a latex (Mooney viscosity MLX +473) obtained by blending (latex blend) with latex (Mooney viscosity ML1+4 !r O) was used.

(Comparative example -/) 0.2 g of molecular weight regulator! The procedure of Example 7 was followed except that t-dodecylmercaptan was used in the r part.

(Comparative Example-2) Molecular weight regulator was added to 0. The procedure of Example 7 was followed except that 0 part of t-dodecyl mercaptan was used.

(Comparative Example-3) Molecular weight regulator was Q. The same procedure as in Example 1 was followed except that the otr portion was replaced with t-dodecylmercaptan.

(Comparative Example-4) SBR latex used in Comparative Example-2 and Comparative Example-3 (Mooney viscosity ML1+4 !r O and /!/, respectively)
/:L latex blended SBR latex (
Example- except that Mooney viscosity MLl+97) was used.
According to /.

[2] Evaluation as a mixture (Example S ~ 1, Comparative Example S ~ 2) (Example 3) 5 parts by weight of the rubber-containing asphalt obtained in Example 1 and 3
93 parts by weight of the aggregate shown in the table (a mixture of No. S crushed stone, No. 6 crushed stone, No. 3 crushed stone, coarse sand, and fine sand and 1 stone powder) and 170~×/1
A dense asphalt concrete mixture was obtained by mixing at a temperature of 0.050°C. Pour this mixture into a double-sided pot for 7S at 0℃.
It was compacted several times and subjected to Marshall stability tests in accordance with the asphalt pavement guidelines. The evaluation results are shown in Table D.

(Example 6) The procedure of Example 3 was followed except that the asphalt composition obtained in Practical Example 2 was used as the rubber-containing asphalt.

(Example 7) Example 3 was followed except that the asphalt composition obtained in Example q was used as the rubber-containing asphalt.

(Comparative Example-Y) The procedure of Example-3 was followed except that the asphalt composition obtained in Comparative Example-2 was used as the rubber-containing asphalt.

(Comparative Example 6) The same procedure as in Actual Example 6 was conducted except that the asphalt composition obtained in Comparative Example 3 was used as the rubber-containing asphalt.

(Comparative Example-7) Straight asphalt (penetration 60 to θ, manufactured by Showa Shell Sekiyu Co., Ltd.)! r parts by weight and the aggregate shown in Table 3 (
A mixture of No. S crushed stone, No. 6 crushed stone, No. 7 crushed stone, coarse sand, fine sand, and stone powder) was mixed at a temperature of 130 to ibo° C. to obtain a dense-grained asphalt concrete mixture.

Pour this mixture on both sides at 3°C! It was compacted once at a time and a Marshall stability test was conducted in accordance with the asphalt pavement guidelines. The evaluation results are shown in Table ←.

*) Stiffness is the value obtained by dividing the stability by the flow value (S
/F), and according to the results of a nationwide survey on plastic flow in asphalt pavement conducted by the Ministry of Construction1), it is shown to be relatively correlated with rutting.

1) Report of the 3.2nd Ministry of Construction Study Group, Civil Engineering Research Center, p-77-231I.

lθ, 7979 (Effects of the Invention) As described above, the asphalt composition blended with the rubber latex of the present invention has greatly superior asphalt properties such as toughness and tenacity, while exhibiting low high-temperature viscosity, which is an indicator of workability. Since it can be kept low, it can be seen that the balance between asphalt performance and workability, which has traditionally been a trade-off, has been significantly improved. In addition, the marshall stability and stiffness of the pavement mixture are high, and when actually used in pavement construction, workability is good, and rut resistance and
A road with excellent wear resistance can be obtained.

[Brief explanation of drawings]

FIG. 1 shows a typical molecular weight distribution of SBR latex used in Examples and Comparative Examples. It can be seen that the molecular weight distribution of the SBR latex of the present invention using 1-octyl mercaptan as a molecular weight regulator is extremely broader than that of a conventional SBR latex using 1-dodecyl mercaptan. FIGS. 2 and 3 are graphs plotting toughness and tenacity, which are indicators of asphalt performance, and asphalt high temperature viscosity (ito°C), which is an indicator of workability (workability).

Claims (2)

[Claims] (1) (a) n-octyl mercaptan 0.05-5.
Contains at least 30 parts by weight of emulsion-polymerized styrene-butadiene copolymer with 0 parts by weight as an essential component of the molecular weight modifier, and (b) 15% by weight or more of a component with a molecular weight of 4.5 x 10^4 or less. , and contains 30 or more components by weight with a molecular weight of 5.0×/10^5 or more. The amount of bound styrene is 10 to 35% by weight, the Mooney viscosity (M
An asphalt composition characterized in that 1 to 10 parts by weight of a styrene-butadiene copolymer having a L_1_+_4, /00°C) of 50 to 140 is blended to 100 parts by weight of asphalt. (2) An asphalt pavement composition characterized by mixing the asphalt composition according to claim 1 with aggregate.