WO2017076814A1

WO2017076814A1 - Binder composition for light coloured pavement

Info

Publication number: WO2017076814A1
Application number: PCT/EP2016/076256
Authority: WO
Inventors: Akira Seo; Kentarou NOGUCHI
Original assignee: Shell Internationale Research Maatschappij B.V.; Shell Oil Company
Priority date: 2015-11-02
Filing date: 2016-10-31
Publication date: 2017-05-11
Also published as: SA518391432B1; JP6607386B2; MY190735A; JP2017088643A

Abstract

A binder composition for a light-coloured pavement, which contains a petroleum-based solvent extracted oil, a petroleum resin, a SEBS having a styrene content of 25-35% and an ethylene-ethyl acrylate copolymer (EEA) having an EA content of 10-25% and a melt mass flow rate (MFR) 5 of 0.5 g/10 mm to 2.5 g/10 mm, and is characterised in that -0.6x + 3.1 ≤ y ≤ -0.5x + 6.1 and 0 ≤ y ≤ 2.8, where the content of the SEBS is denoted by y (wt.%) and the content of the EEA is denoted by x (wt.%).

Description

BINDER COMPOSITION FOR LIGHT COLOURED PAVEMENT

Field of the Invention

The present invention relates to a binder

composition for a light-coloured pavement, which is used to provide a coloured pavement on a park, walkway, or the like, and more specifically relates to a preferred binder composition for a light-coloured pavement, by which ease of application can be improved by preventing stringiness during paving.

Background of the Invention

Asphalt binders are often mixed with aggregates or the like and used as road paving materials. In recent years in particular, when coloured pavements have been installed on public parks, walkways, and the like, use has been made of binder compositions for light-coloured pavements, which can be coloured through the addition of pigments and the like. Binder compositions for light- coloured pavements are transparent amber coloured asphalt binder replacements produced by mixing petroleum resins, rubbers, elastomers, petroleum-based heavy oils, and the like (for example, see Japanese Patent Application

Publication No. 2009-155909) . Such binder compositions for light coloured pavements are obtained by, for example, blending prescribed proportions of resins, thermoplastic elastomers and petroleum-based softening agents, and antioxidants and the like are also added according to need .

When actually laying this type of binder composition for a light-coloured pavement on a public park, walkway, or the like, it is essential to heat the binder

composition for a light-coloured pavement to a temperature of approximately 150-200°C, mix the binder composition with an aggregate and improve fluidity so as to obtain a liquid in order to improve ease of

application. This liquefied mixture of the binder composition for a light-coloured pavement and the aggregate is then laid on a road. At this stage where the mixture is laid, if the temperature of the once heated binder for a light-coloured pavement is lower than approximately 120-130°C, so-called stringiness occurs when the mixture is handled. Stringiness means that the binder becomes more viscous and forms a so-called mucoid state, and when exposed to this mucoid state, the viscous liquid stretches into strings. If such stringiness occurs in a binder for a light-coloured pavement, the ease of application of the binder significantly deteriorates. In addition, if a walkway is paved with a binder for a light-coloured pavement for which the ease of application has deteriorated, there are concerns that the expected durability and strength cannot be achieved. As a result, it was essential in the past to carry out fine

temperature control so that the temperature of the binder did not fall below approximately 120-130°C in order to prevent the occurrence of stringiness, and it was not always possible to reduce the amount of effort required for installation.

Therefore, there was a particular need in the past for a constitution in which this type of fine temperature control was not required by using a binder in which stringiness hardly occurred even at temperatures of approximately 120-130°C.

In order to prevent the occurrence of stringiness, a method of reducing viscosity by intentionally reducing the content of polymer components contained in a binder composition for a light-coloured pavement was first considered. However, by reducing the content of polymer components in the binder, strength and Dynamic Stability (DS) are actually reduced. Therefore, there was a need to provide a binder for a light-coloured pavement, in which it is possible to prevent a decrease in strength or DS while suppressing the occurrence of stringiness by reducing viscosity by intentionally reducing the content of polymer components.

As a result, the present invention was devised with the above-mentioned problems in mind, and the purpose of the present invention is to provide a binder composition for a light-coloured pavement in which it is possible to suppress a decrease in strength or DS while preventing the occurrence of stringiness even if the temperature of the binder falls below approximately 120-130°C.

Summary of the Invention

In order to obtain a binder that scarcely undergoes stringiness even at temperatures of approximately 120- 130°C, the inventors of the present invention lowered the viscosity of the binder by reducing the content of polymer components contained in the binder composition for a light-coloured pavement and added an ethylene-ethyl acrylate copolymer (EEA) , thereby inventing a binder composition for a light-coloured pavement in which a decrease in strength or DS caused by the reduction in content of polymer components can be suppressed.

The binder composition for a light-coloured pavement contains a petroleum-based solvent extracted oil, a petroleum resin, a SEBS having a styrene content of 25-

35% and an ethylene-ethyl acrylate copolymer (EEA) having an EA content of 10-25% and a melt mass flow rate (MFR) of 0.5 g/10 mm to 2.5 g/10 mm, and is characterised in that -0.6x + 3.1 < y < -0.5x + 6.1 and 0 < y < 2.8, where the content of the SEBS is denoted by y (wt.%) and the content of the EEA is denoted by x (wt.%) .

The binder composition for a light-coloured pavement may be further characterised in that it contains 0.2-2.0 wt.% of an anti-stripping agent.

The present invention, which comprises the features mentioned above, has a penetration (at 25°C) of 40-70 (0.1 mm), has a softening point of 56°C or higher, has a viscosity (at 180°C) of 800 mPa-s or lower, has a Dynamic

Stability (DS) of 800 times/mm or higher and underwent no stringiness. Therefore, even if the temperature of the binder falls below approximately 120-130°C, it is possible to suppress a decrease in strength or DS while preventing the occurrence of stringiness.

Brief Description of Drawings

FIG. 1 is a schematic diagram showing the

relationship between the content of SEBS and that of EEA.

FIG. 2 is a diagram for explaining the details of a DS measurement method.

FIG. 3 is a diagram that shows the amount of depression (mm) relative to test time (min) , with the start of a DS measurement test being taken as the start point .

FIG. 4 is a diagram that shows the relationship between the content of SEBS and that of EEA, as shown in FIG. 1, for a variety of working examples and comparative examples .

Detailed Description

A binder composition for a light-coloured pavement according to an embodiment of the present invention will now be explained in detail. In order to solve the problems mentioned above, the inventors of the present invention invented a binder composition for a light-coloured pavement, which contains a petroleum-based solvent extracted oil, a petroleum resin, a SEBS having a styrene content of 25-35% and an ethylene-ethyl acrylate copolymer (EEA) having an EA content of 10-25% and a melt mass flow rate (MFR) of 0.5 g/10 mm to 2.5 g/10 mm, and is characterised in that if the content of the SEBS is denoted by y (wt.%) and the content of the EEA is denoted by x (wt.%), y > -0.6x+ 3.1 in order to suppress a decrease in strength and DS, y < - 0.5x+6.1 in order to prevent a deterioration in ease of application, and 0 ≤ y ≤ 2.8 in order to prevent the occurrence of stringiness if the temperature of the binder falls below approximately 120-130°C.

In addition, an anti-stripping agent is added if necessary. The anti-stripping agent is contained at a quantity of 0.2-2 wt.% relative to the overall binder composition for a light-coloured pavement. Explanations will now be given of the constituent components of the binder composition for a light-coloured pavement in the present invention, and of the reasons for limiting these.

The petroleum-based solvent extracted oil is an extracted oil produced in a solvent extraction process carried out when a lubricating oil is produced from crude oil, and is an oily substance rich in aromatic components and naphthenic components (see "Before petroleum products are made", FIG. 6-1 "General lubricating oil

manufacturing processes", published by The Petroleum Association of Japan, November 1971, page 99; and "New

Petroleum Dictionary", edited by The Institute of

Petroleum, 1982, page 304) . It is preferable for this petroleum-based solvent extracted oil to be a component that acts as a softening agent when added to the binder composition, has a boiling point of 350°C or higher, has a kinematic viscosity at 60°C of 300-800 mm²/s, has a flash point of 250°C or higher and has an aromatic component content of 65% or higher.

An example of this type of petroleum-based solvent extracted oil is the Bright Stock Extract, extracted by means of solvents such as phenol, N-methylpyrrolidone, liquid sulfur dioxide and furfural in a crude oil refining process. From the perspectives of good

workability and resistance to rutting, it is preferable for the content of this petroleum-based solvent extracted oil to be approximately 50-70 wt . % .

The petroleum resin is a polymer of degradation products obtained when producing ethylene or propylene through thermal degradation of naphtha, and a resin having a high content of cyclopentadiene (CPD) or dicyclopentadiene (DCPD) has a high softening point. The petroleum resin is a colourless-to-pale yellow resin having a molecular weight of approximately 200-2000, and generally 1000-1500, and a softening point of 100-150°C. From the perspective of good workability, it is

preferable for the content of this petroleum resin to be 20-40 wt.%.

The SEBS is a block copolymer obtained by removing all double bonds from the butadiene blocks in a styrene- butadiene-styrene block copolymer (SBS) through

hydrogenation, and has far better heat resistance and weather resistance than SBS. However, because the flexibility of the molecular chain is altered by the hydrogenation, the effect achieved by adding a SEBS to an asphalt binder composition is different from that achieved by adding an SBS . The SEBS must have a styrene content of 25-35%. This styrene content is preferably 28-33%.

Because a material having excellent elasticity can be formed by using a SEBS having the physical properties mentioned above, by using this SEBS in the binder composition for a light-coloured pavement according to the present invention, it is possible to improve DS and prevent brittle fracture caused by hardening.

Moreover, in the binder composition for a light- coloured pavement of the present invention, it must be assumed that DS is achieved mainly by the EEA that is described below. However, by increasing the concentration of the EEA in isolation in order to improve DS by means of the EEA alone, the binder composition actually becomes too hard and the degree of compaction can decrease when a mixture is produced. Therefore, adding a certain quantity of an elastic SEBS contributes to an improvement in DS, even to a small extent .

In addition, the content of the SEBS is 0-2.8 wt . % . In cases where the content of the SEBS exceeds 2.8 wt.%, if the temperature of the binder composition for a light- coloured pavement falls below approximately 120-130°C, so-called stringiness occurs when the composition is handled. Stringiness means that the binder becomes more viscous and forms a so-called mucoid state, and if a viscous liquid comes into contact with this mucoid state, the viscous liquid is stretched into strings. Therefore, by setting the content of the SEBS to be 2.8 wt.% or lower in the present invention, it is possible to suppress stringiness during installation and prevent a significant decrease in ease of application.

In addition, depending on the content of the EEA, the content of the SEBS may be 0 wt.%. In other words, it is possible for a SEBS not to be added to the binder composition for a light-coloured pavement of the present invention .

The EEA is a thermoplastic resin that is a copolymer of ethylene and ethyl acrylate, and is a resin that maintains pliability across a wide temperature range. This EEA has an EA content of 10-25% and has a melt mass flow rate (MFR) of 0.5-2.5 g/10 mm. If the EA content is lower than 10% or if the MFR is lower than 0.5 g/10 mm, problems occur, such as the pliability of the binder composition decreasing as the viscosity increases, and the viscosity increasing. Meanwhile, if the EA content exceeds 25% or if the MFR exceeds 2.5 g/10 mm, the DS decreases .

As mentioned above, the EEA is mainly responsible for improving the DS, but the content of the EEA is determined according to a relationship with the content of the SEBS.

FIG. 1 is a schematic diagram showing the

relationship between the content of SEBS and that of EEA, where the horizontal axis shows the content of EEA (x) , the vertical axis shows the content of SEBS (y) , and the units for both of these content values are wt . % .

Here, the binder composition for a light-coloured pavement of the present invention falls within the approximately parallelogram-shaped region enclosed by the solid lines. In the region enclosed by the solid lines, the SEBS content (y) that forms the upper and lower boundaries is such that 0 ≤ y ≤ 2.8, as mentioned above. In addition, the straight line that forms the left-hand boundary of the region enclosed by the solid lines is such that y = -0.6x+3.1, and the straight line that forms the right-hand boundary of the region enclosed by the solid lines is such that y = -0.5x+6.1. That is, the region enclosed by the left-hand and right-hand

boundaries is represented by the formula -0.6x+3.1 < y < -0.5x+6.1.

In cases where y < -0.6x+3.1, the SEBS content relative to the EEA content (in other words, the EEA content relative to the SEBS content) is too low, meaning that the desired DS cannot be achieved. Meanwhile, in cases where y > -0.5x+6.1, the viscosity at 180°C increases, meaning that ease of application deteriorates.

Therefore, the EEA content (x) and the SEBS content (y) must fall within the ranges of the present invention mentioned above.

In order to prevent stripping of the binder

composition for a light-coloured pavement from the aggregate in the present invention, it is preferable to add an anti-stripping agent. A dimer acid can be

advantageously used as the anti-stripping agent, but this dimer acid is produced through polymerisation of a C18 unsaturated fatty acid that uses a plant-based oil/fat as a raw material. By incorporating this dimer acid in the binder composition, the dimer acid acts to prevent stripping of the binder composition from the aggregate when the binder composition is mixed with the aggregate. A preferred anti-stripping agent in the present invention is a dimer acid, but is not limited thereto.

In addition, a resin acid may also be used as the anti-stripping agent .

A resin acid is a carboxyl group-containing

polycyclic diterpene having 20 carbon atoms, which is a rosin containing 1 or more acids selected from among abietic acid, dehydroabietic acid, neoabietic acid, pimaric acid, isopimaric acid and palustric acid. Here, rosins include gum rosins, wood rosins, liquid rosins, and the like. These rosins can be classified into gum rosins, wood rosins, and the like, according to differences in place of origin and collection method, but at the very least can be obtained as residual components when subjecting pine resin to steam distillation.

Components in these rosins are mixtures containing abietic acid, palustric acid, neoabietic acid,

dehydroabietic acid, pimaric acid, sandaracopimaric acid, isopimaric acid, and the like. These rosins generally soften at approximately 80°C and melt at 90-100°C.

Moreover, a variety of resin acids, such as abietic acid, dehydroabietic acid, dihydroabietic acid,

tetrahydroabietic acid, palustric acid, neoabietic acid and levopimaric acid, are contained in these rosins, but these resin acids may be refined and used in isolation.

This anti-stripping agent is contained at a quantity of 0.2-2 mass % relative to the overall mass of the binder composition. If the content of this anti-stripping agent is lower than 0.2 mass %, stripping occurs when the binder composition is mixed with the aggregate and it is not possible to improve the stability of the binder composition obtained as a final product. Meanwhile, if the content of this anti-stripping agent exceeds 2 mass %, this stability improvement effect reaches saturation point and there is a significant increase in raw material costs due to the increase in added quantity of this expensive anti-stripping agent. That is, even if the content of the anti-stripping agent exceeds 2 mass %, the stability is not greatly improved and there is an adverse effect in terms of raw material costs.

In addition, it is preferable for this anti- stripping agent to be contained at a quantity of 0.2-1 mass % relative to the overall mass of the binder

composition. By setting the upper limit for the content of this anti-stripping agent to be 1 mass %, it is possible to minimise an increase in raw material costs while improving the stability of the binder composition and improving cost-effectiveness.

Working Example 1

Embodiments of the present invention will now be explained in detail by giving examples of test methods, working examples and comparative examples, but the present invention is not limited to these working

examples. In addition, in cases where the symbol % is used in the examples given below, this means wt . % .

In the present invention, working example and comparative example samples were prepared in order to carry out experimental investigations. Preparing these samples involved adding a prescribed quantity of the above-mentioned SEBS while the petroleum-based solvent extracted oil is melted at a temperature of approximately 180°C, and then adding the above-mentioned petroleum resin, dimer acid and EEA at the blending proportions mentioned above. Mixing was carried out using a homomixer, and mixing and stirring were carried out for a period of 3-5 hours at a rotational speed of 1500-5000 rpm.

Following completion of the mixing, the temperature of the binder composition was adjusted to 190-200°C. In addition, the quantity of composition produced was 1.8 kg in each case.

The obtained working example and comparative example samples were subjected to performance tests in terms of penetration (25°C), softening point, viscosity (at 180°C), DS, and presence/absence of stringiness, as shown in Table 1. Detailed explanations will now be given of the test methods.

Table 1

Table 1 (continued)

Table 1 (continued)

Table 1 (continued)

Table 1 (continued)

Table 1 (continued)

The penetration (25°C) was measured in accordance with JIS K 2207 (Petroleum asphalt - penetration test methods) . This value is preferably not lower than 40 (0.1 mm) and not higher than 70 (0.1 mm) .

The softening point was measured in accordance with

JIS K 2207 (Petroleum asphalt - softening point test methods) . This value is preferably 56°C or higher.

The viscosity (at 180°C) was measured under the conditions specified in JPI-5S-54-99 (Asphalt - viscosity test methods using rotational viscometer) at a

measurement temperature of 180°C using a SC4-27 spindle at a spindle rotation speed of 20 rpm.

The viscosity (at 180°C) is related to the hardness of the asphalt mixture at the time of application, and if the viscosity increases, the ease of application

deteriorates and it becomes impossible to obtain the desired pavement. Therefore, this viscosity is preferably 800 mPa-s or lower.

The strength of this asphalt binder composition is assessed from the DS on the basis of the "B003 wheel tracking test methods" disclosed in the Handbook of investigation and testing of pavement (edited by the Japan Road Association) . This DS is used exclusively as an indicator for measuring the strength of road paving materials. However, because a similar improvement in strength may also be required when the binder composition is used in a waterproofing material, an adhesive material, or the like, sufficient consideration has been given to evaluating by means of DS. Therefore, even if DS is used as an evaluation indicator in the present invention, the binder composition can be used not only in a road paving material, but also in other applications such as

waterproofing materials and adhesive materials. A method for measuring DS will now be explained. DS is an indicator for evaluating resistance to fluidity (resistance to rutting) of the binder composition at high temperatures, and is measured using a wheel tracking tester. The wheel tracking test is carried out at 60°C, to simulate a road surface in summer. A test piece, which is prepared by mixing the binder composition with an aggregate (stones obtained by crushing rocks) adjusted to the desired particle size shown in Table 2, is aged for 5 hours at 60°C, and a wheel is then run over the test piece for 1 hour. In the working examples and comparative examples, a test piece 5 measuring 30 ^χ 30 ^χ 5 cm was aged, as shown in FIG. 2. In FIG. 2, 11 designates a wheel .

Table 2

Next, a downward load of 686 N is applied to the test piece 5 by a wheel 11, and the wheel 11 is run back and forth at a rate of 42 passes per minute in the direction shown by the arrow. Here, the running position of the wheel 11 was kept constant, with no deviation.

FIG. 3 shows the amount of depression (mm) relative to test time (min) , with the start of a DS measurement test being taken as the start point. With the start of the test being taken as the start point, the amount of depression caused by the wheel 11 running back and forth increases as the duration of the test increases. The amount of depression is the depth (mm) of depression in the depth direction from the surface of the test piece 5.

When measuring the DS, the amount of depression after 45 minutes has passed since the start of the test is disregarded. The reason for this is that for 45 minutes after the start of the test, the amount of depression is determined by factors such as the binder composition embedding with the added aggregate, meaning that it is not possible to evaluate resistance to fluidity in a real sense.

When measuring the DS, the start of the test is taken to be the start point, and attention is focused on the amount of deformation d (mm) of the asphalt binder in the 15 minute period between 45 minutes and 60 minutes from the start of the test. The value of d can be calculated by determining the difference between the amount of depression 60 minutes from the start of the test and the amount of depression 45 minutes from the start of the test. The DS can be determined using formula

(2) below.

The DS can be determined from: DS (times/mm) = number of tyre runs between 45 minutes and 60 minutes from the start of the test / d (mm) (2) .

In cases where the frequency of reciprocation of the wheel 11 is 42 (times / min) , formula (2) can be

rewritten as formula (2) ' .

DS (times/mm) = 630 (times) / d (mm) (2) '

The numerator in formula (2) ' is 42 (times/min) ^χ 15 (min) = 630 (times) . That is, the DS can be determined from the number of tyre runs in a 15 minute period relative to d (mm) . As the value of DS increases, the amount of deformation of the binder composition per se decreases, resistance to rutting increases and strength increases .

Moreover, the DS was tested not only for the binder composition, but also for a test piece obtained by mixing an aggregate adjusted so as to have the particle size shown in Table 2 (crushed stone, limestone powder, or the like) and the binder composition under prescribed conditions that are explained later, and then moulding, which is similar to an actual road paving material.

As the value of DS increases, the strength of the asphalt increases and it is possible to provide a paving material having good resistance to rutting. In the present invention, the DS value is preferably 800 times/mm or more, and more preferably 1500 times/mm or more.

An explanation will now be given of a specific method for preparing a test piece used to measure DS using the binder composition of the present invention.

A test piece is prepared by using crushed stone comprising hard sandstone as the aggregate and using stone dust obtained by crushing limestone in order to adjust the blending proportion of fine grain components (constituent components having small particle diameters) . Moreover, materials other than the crushed stone and stone dust mentioned above, such as beach sand or recovered dust, cause fluctuations in DS, and are therefore not used.

Crushed stone which has a passing mass percentage of 100% for a sieve opening of 600 μηι, 90-100% for a sieve opening of 150 μηι and 70-100% for a sieve opening of 75 μηι, and which has a moisture content of 1% or less, and which therefore conforms to the limestone filler for pavements specified in JIS A 5008, is used as the crushed stone obtained by crushing limestone, which is used to adjust the particle size of the aggregate.

Crushed stone comprising hard sandstone is used as aggregate other than stone dust, and materials that satisfy the properties shown in (1) to (6) below are used.

(1) The water absorption rate is less than 1.5%, and preferably less than 1.0%. (JIS A 1110) . Here, crushed stone having a water absorption rate of 0.64% is used. If the aggregate has a high water absorption rate, the aggregate absorbs the coated asphalt binder, meaning that the quantity of asphalt binder in the mixture decreases. In addition, in the case of an aggregate having a high water absorption rate, the quantity of asphalt binder absorbed varies greatly according to the humidity at time of use and the degree of moisture on the surface, meaning that the quantity of asphalt binder in the mixture fluctuates. Therefore, in order to ensure a fixed

quantity of asphalt binder in the mixture, the water absorption rate must be less than 1.5%, and preferably less than 1.0%.

(2) The apparent density is 2.60-2.70 g/cm³ (JIS A

1110)

Here, crushed stone having an apparent density of 2.66 g/cm³ was used.

(3) The stability is 6% or lower, and preferably 3% or lower (JIS A 1122)

Here, crushed stone having a stability of 2.4% was used. Here, stability means stability against freezing and thawing. As the stability value decreases, breaking of the aggregate during freezing and thawing is reduced.

Pavement design and construction guidelines stipulate a stability of 12% or less, but in order to suppress variations in aggregate properties, the present invention stipulates a value that is half that in these guidelines.

(4) The abrasion weight loss is 20% or lower, and preferably 15% or lower (JIS A 1121)

Here, crushed stone having an abrasion weight loss of 12.6% was used. An abrasion weight loss test is a test that evaluates the hardness and resistance to abrasion of an aggregate, that is, the durability of an aggregate. If the abrasion weight loss exceeds 20%, the degree of rutting increases, and the abrasion weight loss in this case is therefore 20% or lower, and preferably 15% or lower .

(5) The content of soft particles is 5% or lower, and preferably 3% or lower (JIS A 1126)

Here, crushed stone having a soft particle content of 2.5% was used. The content of soft particles is evaluated using a test in which it is assessed whether a scratch is left by a brass rod (having a Mohs ' hardness of 3-4), that is, a test in which it is assessed whether an aggregate is harder or softer than brass. Like the abrasion weight loss test, the soft particle content test is a test that evaluates the hardness and resistance to abrasion of an aggregate, that is, the durability of an aggregate. In general, the content of soft particles must be 5% or lower. (See Handbook of investigation and testing of pavement A008)

(6) The content of elongated or flat stone fragments is 10.0% or lower, and preferably 5.0% or lower (see Pavement design and construction guidelines (regulatory limits) and Handbook of investigation and testing of pavement A008 (test methods)) .

Here, crushed stone having a content of elongated or flat stone fragments of 2.8% was used. Here, stone fragments having a long axis/short axis ratio of 3 or higher are generally used as elongated or flat stone fragments. If elongated or flat stone fragments are contained, a pavement or test piece can be easily

deformed by a load from a certain direction. That is, if a large quantity of elongated or flat stone fragments are contained, the stone fragments become aligned with each other and a pavement or test piece can be easily deformed by a load applied in a direction perpendicular to this alignment .

Therefore, when measuring the resistance to rutting (DS) , obtained values can fluctuate greatly if

contamination by elongated or flat stone fragments is not suppressed.

Using crushed stone and stone dust that satisfy these properties as aggregates, the aggregate formulation shown in Table 2 was prepared and test pieces were prepared under the conditions shown in Table 3.

Broadly speaking, actual preparation of the test pieces comprises 2 stages, namely mixing the binder composition and the aggregate, and then surface

compaction. For the mixing, 567 g of a binder composition heated to 175°C and 10,176 g of an aggregate which was heated to 185°C and composed so as to have the particle size mentioned above (hereinafter, this adjusted particle diameter is referred to as the composed particle

diameter), are prepared.

First, the aggregate was placed in a mixer and standardised by being mixed for 60 seconds. The mixing was temporarily stopped, 567 g of the binder composition was introduced into the mixer, and the binder composition and aggregate were then mixed for a period of 120 seconds. Following completion of the mixing, the binder composition and aggregate were placed in a wheel tracking test template (having internal dimensions of height: 30.0 cm, width 30.0 cm, depth: 5.0 cm) and subjected to surface compaction.

For the surface compaction, the mixed binder was subjected to surface compaction by rolling with a cylindrical roller having a radius of 460 mm under the compaction temperature conditions shown in Table 3. The surface compaction is carried out in two stages, namely primary surface compaction and secondary surface

compaction. The mixed binder is then allowed to dry for a period of 8 hours.

Table 3

Conditions for mixing asphalt composition and aggregate

TA-381 manufactured

Apparatus used for mixing by Freesia Macross

(30 kg mixer)

Quantity of asphalt composition 567 g

Temperature of asphalt composition 175°C

Quantity of aggregate having

10,178 g composed particle size

Temperature of aggregate having

185°C composed particle size

Duration of mixing asphalt

120 sec composition and asphalt

Porosity of test piece 3.80%

Degree of compaction 100%

Surface compaction conditions

Surface compaction temperature 165°C

Cylindrical roller,

Shape of surface compaction roller

radius 460 mm

Primary compaction pressure, 0.4 MPa, 24 times number of times (12 returns)

Secondary compaction pressure, 0.75 MPa, 24 times number of times (12 returns) Because tests for determining the presence/absence of stringiness are not particularly specified in Japan Industrial Standards or the like, 2 layers of thick cotton gloves were worn on both hands, samples of the asphalt binder compositions of the working examples and comparative examples were heated to 130°C, 3-5 g samples were placed in the palms of the left and right hands, and the samples were then brought into contact with each other by bringing the hands together. Next, when the hands were slowly drawn apart by a distance of 5 cm or more, it was confirmed visually whether or not

stringiness had occurred. As a result, cases in which 1 string or more were observed were judged to be "stringy" and cases in which not even 1 string was observed were judged to be "non-stringy" .

Working Examples 1-15 and Comparative Examples 1-9

Detailed explanations will now be given of working examples and comparative examples .

Representative properties of the petroleum-based solvent extracted oil used in the present test are a kinematic viscosity at 60°C of 512 mm²/s, a flash point of 338°C and an aromatic component content of 65.9%.

Representative properties of the petroleum resin are a softening point of 140°C, an acid value, as stipulated in JIS K0070, of 0.1 mg KOH, a bromine value, as stipulated in JIS K2543, of 25 g, and an average molecular weight in terms of polystyrene, as measured using a GPC method, of approximately 1000.

The SEBS used in the present test has a 10% toluene solution viscosity of 1800 mPa-s at 25°C and a styrene content of 30%. Tests were carried out on 5 types of EEA, namely EEAl to EEA5. EEAl, which had an MFR of 0.5 g/10 mm and an EA content of 10 wt.%, was used in Working Example 13, EEA2, which had an MFR of 0.5 g/10 mm and an EA content of 16 wt.%, was used in Working Examples 1 to 12 and

Comparative Examples 1 to 8, EEA3, which had an MFR of 0.5 g/10 mm and an EA content of 25 wt.%, was used in Working Example 14, EEA4, which had an MFR of 1.5 g/10 mm and an EA content of 20 wt.%, was used in Working Example 15, and EEA5, which had an MFR of 3.0 g/10 mm and an EA content of 30 wt.%, was used in Comparative Example 9. Moreover, among these EEAs, EEAl to EEA4 had MFR and EA content values that fell within the ranges specified in the present invention, but EEA5 had MFR and EA content values that fell outside the ranges specified in the present invention.

In order to prevent stripping between the binder composition and the aggregate and achieve a

compatibilising effect, a dimer acid (a dimerised tall oil fatty acid having 36 carbon atoms and an acid value of 190-210) was used as an anti-stripping agent in the present test.

The content ratios of the components in Working Examples 1 to 15 all fell within the ranges specified in the present invention. Working Examples 1 to 15 all satisfied the standards for the evaluation criteria mentioned above. That is, the binder compositions for light coloured pavements according to Working Examples 1 to 15 all had a penetration (25°C) of 40-70 (0.1 mm), a softening point of 56°C or higher, a viscosity (at 180°C) of 800 mPa-s or higher and a DS of 800 times/mm or higher and were evaluated as being "non-stringy" . Among these working examples, Working Examples 1-3, 5-6, 13 and 14 each contained 2.5-5.0% of EEA2 and 2.0- 2.5% of the SEBS, but all had a DS of 1500 times/mm or higher, had a viscosity (at 180°C) of 600 mPa-s or lower and were particularly excellent in terms of strength and ease of application.

Comparative Example 1 had a SEBS content of greater than 2.8%, which exceeded the upper limit for SEBS content specified in the present invention. As a result, stringiness occurred in Comparative Example 1.

In Comparative Examples 2 to 5, the EEA content x and the SEBS content y were such that y < -0.6x+3.1, and therefore fell outside the range specified in the present invention. As a result, Comparative Examples 2 to 5 all had a DS of less than 800 times/mm, had low strength and exhibited inferior durability during paving.

In Comparative Examples 6 to 8, the EEA content x and the SEBS content y was such that y > -0.5x+6.1, and therefore fell outside the range specified in the present invention. As a result, the viscosity at 180°C exceeded the upper limit in Comparative Examples 6 to 8, and the ease of application deteriorated.

Comparative Example 9 used EEA5, meaning that the value for DS was below the lower limit .

In addition, FIG. 4 is a diagram that shows the relationship between the content of SEBS and that of EEA, as shown in FIG. 1, for the working examples and

comparative examples given above. The line segment for which y = -0.6x+3.1 exactly shows the position of the boundary between the plots for Comparative Examples 1, 3,

4 and 5 and the plots for Working Examples 1, 13-15, 4, 7 and 8. In addition, the line segment for which y = - 0.5x+6.1 shows the position of the boundary between the plots for Comparative Examples 6 to 8 and the plots for Working Examples 10 to 12.

Claims

C L A I M S

1. A binder composition for a light-coloured pavement, which contains a petroleum-based solvent extracted oil, a petroleum resin, a SEBS having a styrene content of 25- 35% and an ethylene-ethyl acrylate copolymer (EEA) having an EA content of 10-25% and a melt mass flow rate (MFR) of 0.5 g/10 mm to 2.5 g/10 mm, and which is characterised in that -0.6x + 3.1 < y < -0.5x + 6.1 and 0 < y < 2.8, where the content of the SEBS is denoted by y (wt.%) and the content of the EEA is denoted by x (wt.%) .

2. The binder composition for a light-coloured pavement according to claim 1, which is characterised by

containing 0.2-2.0 wt.% of an anti-stripping agent.

3. The binder composition for a light-coloured pavement according to claim 1 or claim 2, wherein the petroleum- based solvent extracted oil has a boiling point of 350°C or higher, has a kinematic viscosity at 60°C of 300-800 mm²/s, has a flash point of 250°C or higher and has an aromatic component content of 65% or higher.

4. The binder composition for a light-coloured pavement according to any previous claim, wherein the binder composition comprises 50-70 wt.% of petroleum-based solvent extracted oil.

5. The binder composition for a light-coloured pavement according to any previous claim, wherein the petroleum resin has a molecular weight of 200-2000 and a softening point of 100-150°C.

6. The binder composition for a light-coloured pavement according to any previous claim, wherein the binder composition comprises 20-40 wt.% of petroleum resin.

7. The binder composition for a light-coloured pavement according to any previous claim, wherein the binder composition comprises up to 2.8 wt . % of SEBS.

8. The binder composition for a light-coloured pavement according to any of claims 2 to 7, which is characterised by containing 0.2-1.0 wt . % of an anti-stripping agent.

9. The binder composition for a light-coloured pavement according to any of claims 2 to 8, wherein the anti- stripping agent comprises a dimer acid or a resin acid.