BINDER COMPOSITION

Field o£ the Invention

This invention relates to a binder composition for use in road paving, waterproofing materials, adhesives and so on, and in particular relates to a binder composition with superior heating efficiency at the time of melting and at the time of use. Background of the Invention

Asphalt (hereinafter referred to as "asphalt binder"}, generally blended with aggregates, has been widely used as a road paving material.

In road asphalt paving work, it is necessary to render the asphalt binder into liquid form, to improve flow properties, by heating it to a temperature in the range of from 150° to 200 ⁰ C and mixing it with the aggregate in order to improve the ease of implementing the work. The mixture of asphalt binder in this liquid form and aggregate is spread on the roadway and the road surface is finished off by tamping it down under rolling pressure by means of a road roller or the like. In recent years in particular, bright-colour binders which can be coloured by adding pigments or the like have been used in the case of coloured .paving works in public parks or on pathways. Bright -colour binders are, for example, light-brown, transparent asphalt -binder substitutes manufactured by mixing petroleum resins, rubbers, elastomers, petroleum-based heavy oils and the like. Such bright-colour binders include, for example, instances where resins and/or thermoplastic elastomers are

blended with petroleum-based softening agents in the requisite proportions, anti-oxidants and so on being added where necessary.

The asphalt binder or bright colour binder is used not only as a road paving material, but also as a waterproofing material to prevent water leakage in the roofs of dwelling houses or the tops of concrete structures. For this sort of waterproofing work, a technique is used whereby a waterproof layer is formed by blowing or pouring hot -melt asphalt binder onto the places where waterproofing treatment is required. In addition, it is also used as an adhesive by making use of its adhesiveness .

In other words, the asphalt binder or bright- colour binder requires hot-melting at the time of use in all of the cases in which it is used. Hitherto, the general method of heating binders has been to use a heating apparatus such as a heater or gas burner by burning fossil fuels.

However, in such a heating method using a heating apparatus such as a heater or gas burner, whilst it is possible to make the temperature of the heated portion rise in a short time, the rate of temperature rise in the part separated from the heated portion will have lagged behind this, even though the temperature does rise because of heat conduction, convection and the like. For this reason, there have been problems in that the temperature differential within the binder between the heated portion and the portion separated from the heated portion becomes considerable. If the heated portion is heated more than is necessary so as to raise the temperature of the portion separated from the heated portion in the binder, the binder in the heated portion instead ends up being heated

excessively. In consequence, an odour may be emitted from the excessively heated binder because of the production of steam and fumes, and since it may also induce deterioration of the binder itself there will be a deleterious effect on the paving finish or on performance as waterproof asphalt roofing or as an adhesive.

For this reason, there has been a demand for a method which has superior heating efficiency when spreading the mixture of asphalt binder or bright -colour binder and aggregate on roadways and by which it is possible to heat it uniformly without giving rise to a temperature differential overall.

JP 3-271450 (1991) , having as its object uniform heating of asphalt roofing for waterproofing, has proposed an asphalt waterproofing construction method which uses so- called electromagnetic induction heating in which the surface is coated with a particulate substance which has conductivity or an electromagnetic induction effect, such as a metal or an oxide thereof, heating being effected by generation of eddy currents due to induction of an alternating magnetic field.

Methods of radio- frequency heating of a mixture of asphalt binder and aggregate {hereinafter referred to as asphalt mixture) apart from electromagnetic induction heating have also been proposed (for example, see JP 60- 138104 (1985) ) . The technology disclosed in this document heats the asphalt mixture by utilising a high frequency dielectric apparatus.

Similarly, it is shown in JP 62-25801 (1987) , which relates to radio- frequency heating of an asphalt mixture, that the temperature rise when asphalt binder mixed with

large stones as the inorganic matter is irradiated with microwaves is considerably higher than when such large stones are not mixed therein.

In a similar technological concept, asphalt recycling methods have also been disclosed (for example, see JP 7- 197412 (1995}) in which a dielectric heating treatment is applied while material derived from asphalt pavement is being transported, and, in a subsequent step, is mixed with fresh asphalt mixture subjected to a separate heating treatment.

Apparatus for induction heating of asphalt with high heating efficiency has also been disclosed {for example, see JP 2001-143862) .

Further, in addition to manufacturing heated asphalt mixtures for use in paving, methods have been proposed (for example, see JP 10-266114 (1998) ) in which the absorption of microwaves is improved in respect of the vessel for heating the blend of materials.

However, in the methods of heating asphalt mixtures and asphalt roofing in the prior art mentioned above, there is simply radio- frequency heating, and there is no change of any kind effected in the asphalt binder itself, nor is there any mixing of materials of any kind. JP 62-25801, as described above, essentially refers to an improvement in heating efficiency when irradiating with microwaves after mixing large stones with the asphalt binder. It may be said that it has disclosed the concept of mixing matter of some sort in asphalt binder with a view to improving the heating efficiency by electromagnetic induction of the asphalt mixture.

However, the technology of large stones or crushed stones with asphalt binder, which is the technology disclosed in this JP 62-25801, is a method implemented as a method of manufacturing road paving raw material in the prior art and cannot be said to be a disclosure with a view to improving heating efficiency by means of radio- frequency heating as a special step. Furthermore, given that the step in which large stones are mixed in is part of the work- implementation process, there are problems in that the burden of equipment and labour to implement the work increases, and in that a longer time is required for stirring the asphalt binder mixed with the large stones, in order to mix in the stones uniformly, and the increase in labour for stirring is also not inconsiderable. Also, there are applications such as waterproofing or adhesion where mixing large stones with the asphalt binder is not possible, and further it has been necessary, so as to improve heating efficiency by means of radio- frequency heating of the asphalt binder, to maintain radio-frequency heating performance when irradiating the asphalt binder itself before mixing in large stones.

This invention is therefore proposed in the light of these problems just described, and is intended to offer a binder composition which is capable of improving the heating efficiency in the case of irradiation by electromagnetic waves when hot -melting at the time of use, and which is capable of effecting uniform heating overall. Summary of the Invention

The present invention provides a binder composition characterised in that, as a way of resolving the problems described above, it contains an organic compound having

hydroxyl groups and the hydroxyl number is at least 1 mg/KOH/g. The present invention further provides a method of radio-frequency heating of a binder composition, characterised by radio- frequency heating by irradiation with electromagnetic waves of a binder composition which contains an organic compound having hydroxyl groups and wherein the hydroxyl number is at least 1 mgKOH/g.

The inventor has discovered that, if an organic compound having hydroxyl groups is incorporated in the binder composition, heating efficiency is improved by irradiation with electromagnetic waves, and specifically that, if an organic compound having hydroxyl groups is incorporated in the binder composition so that the hydroxyl number is at least 1 mgKOH/g, a significant temperature rise can be observed when irradiating with electromagnetic waves . He has thus invented a binder composition of the structure shown below and a method for radio- frequency heating of the binder composition. Detailed Description of the Invention The binder composition relating to this invention contains an organic compound having hydroxyl groups and the hydroxyl number is not less than 1 mgKOH/g. It can thus be made to have the necessary polarity in order to boost the temperature rise by radio-frequency heating. For this reason, it becomes possible to promote a temperature rise by heating of the binder composition itself, by irradiation with electromagnetic waves of binder compositions such as relate to this invention. Also, given that a uniformly raised temperature in the whole of the heated substance becomes possible, it is possible to eliminate temperature

differentials within the binder composition and, by extension, to suppress generation of noxious odours.

The inventor has undertaken intensive research in order to resolve the problems described above and to offer a binder composition which is capable of improving heating efficiency when irradiating with electromagnetic waves during hot-melting at the time of work, and which effects uniform heating overall. As a result, the inventor has discovered that, when an organic compound having hydroxyl groups is incorporated in the binder composition, this causes an improvement in the efficiency of heating through electromagnetic radiation. The inventor has also discovered specifically that, if the hydroxyl number of the binder composition as a whole containing the organic compound having hydroxyl groups is not less than 1 mgKOH/g, a significant temperature rise can be observed when irradiating with electromagnetic waves of 2450 MHz.

The binder composition used in this invention (hereinafter referred to as the binder composition of this invention) is described below by specifying the constituent elements of which it is made up and the reasons for limiting the values.

For the organic compound having hydroxyl groups it is possible to use any compounds provided they have hydroxyl groups. Alcohols and phenols may be used. Of these, those especially preferred are glycerols, polyethers , polyethylene glycols, higher alcohols (alcohols having more than 2 carbon atoms) and polymers thereof, if they have hydroxyl groups . In hydroxyl groups, the poles are divided into minus on the oxygen atom side and plus on the hydrogen atom side,

and so the dipole moment is large. For this reason, it is possible, by mixing an organic compound having hydroxyl groups into the binder composition, to spread polarity into the composition as a whole. As a result, when the binder composition of the invention is irradiated with electromagnetic waves as described below, it is possible, because of said polarity, to boost the temperature rise due to radio- frequency heating.

It may be thought that any organic compounds containing ketones, amino groups or carboxylic acids rather than hydroxyl groups could boost radio- frequency heating. In particular, as regards carboxylic acids, formic acid (HCOOH, high volatility with boiling point 100 °C) manifests polarity, and can boost radio- frequency heating. However, there are problems in that formic acid, because it has high volatility, is inferior in practical use. Also, if the number or carbons is greater than in acetic acid (CH ₃ COOH) or butyric acid (C ₂ H ₅ COOH) , dimers loosely linking two molecules are generated and the polarity is extinguished, so that the heating effect is reduced. There is also the problem that noxious odours are released.

In the case of amino acids and ketones, because the polar groups are not at the ends or periphery of the molecules but within (at the centre or inside the molecular structure) , the dipole moment of the molecule as a whole is smaller and the heating effect is reduced.

Therefore, rather than organic compounds having carboxylic acids, amino acids or ketones, it is preferable to add organic compounds having hydroxyl groups. The hydroxyl number referred to here denotes to what extent hydroxyl groups are contained within the binder

composition as a whole after the organic compound having hydroxyl groups has been mixed in as described above. The hydroxy1 number shows the amount in mg of potassium hydroxide necessary to neutralise acetic acid bonded with hydroxyl groups in the acetylation of Ig of sample.

This hydroxyl number can be measured on the basis of JIS K 1557-1. According to JIS K 1557-1, the sample is made into a pyridine solution containing acetic anhydride, and the hydroxyl groups are acetylated under pyridine reflux. The reaction is accelerated by using imidazole as a catalyst, and excess acetylation reagent is hydrolysed using water. The acetic acid produced is titrated with a standard sodium hydroxide solution. The hydroxyl number is calculated from the titre difference between the null experiment and the sample experiment .

If the hydroxyl number is less than 1 mgKOH/g, the proportion of hydroxyl groups within the binder composition becomes too small and so there is a problem in that, when irradiating with electromagnetic waves as described below, it does not have the necessary polarity to give the requisite boost to the temperature rise by means of radio- frequency heating.

In contrast, if the hydroxyl number is greater than 200 mgKOH/g, the water resistance of the binder composition decreases {substances with a large hydroxyl number have a high affinity with water) , and so problems arise in that its function as a road paving or waterproofing material or as an adhesive is reduced.

It is preferable if the hydroxyl number is at least 5 mgKOH/g. The reason for this is that when the hydroxyl number is made at least 5 mgKOH/g the proportion of

hydroxyl groups within the binder composition can be increased and a temperature rise of at least 5 ⁰ C by means of radio- frequency heating can be expected, so that an extremely large radio-frequency ^' heating effect can be obtained.

In one embodiment of the invention, the binder composition comprises asphalt binder.

The asphalt binder of this invention may be, for example, straight asphalt (see JIS K 2207) , solvent- deasphalted asphalt (see "Shin Sekiyu Jiten" [New Petroleum Dictionary] , edited by the Institute of Petroleum, 1982, p. 308), blown asphalt (see JIS K 2207) or mixtures of two or more kinds thereof. These asphalt binders are all easy to procure and so are suitable, for example, for use in infrastructure work such as roads. Normally the asphalt binder contains of the order of at least 5.0% by mass of asphaltene .

In another embodiment of the invention, the binder composition is a bright-colour binder composition. Preferably the bright- colour binder composition comprises one or more petroleum resins and one or more petroleum- based solvent -extracted oils. More preferably, the bright- colour binder is a light-brown, transparent asphalt substitute manufactured by mixing petroleum resins, rubbers, elastomers and petroleum-based solvent-extracted oils. Also, the bright-colour binder composition can be used, when applied to road paving, by mixing it with bright-colour aggregate of high light reflectivity. What is referred to here as bright-colour aggregate means those exhibiting pigmentation, and it is possible to impart the requisite colour to the binder composition of this

invention by incorporating same and thereby to effect coloured paving.

Petroleum-based solvent-extracted oils are extracted oils produced during solvent extraction processes when making lubricating oils from crude oil, and are oily substances rich in aromatic and naphthenic components . When these petroleum-based solvent -extracted oils are added to the binder composition, they are the component which acts as a softener, and it is preferable if the boiling point is not less than 350 ⁰ C, the viscosity at 100 ⁰ C is 5 to 100 mPa. second, the flash point is not less than 25O ⁰ C and the aromatic content is not less than 75.0 mass %. An example of such petroleum-based solvent-extracted oils is the solvent -extracted component of Bright Stock extracted by means of solvents such as phenol, N-methylpyrrolidone, liquid sulphur dioxide and furfural in the crude oil refining process .

The binder composition (either an asphalt binder or a bright -colour binder composition) may comprise petroleum resins or thermoplastic elastomers, or hydrogenates thereof .

Petroleum resins are polymers of unsaturated hydrocarbons which are present in thermal cracking fractions in petroleum refining processes. They are bright yellow substances in which the molecular weight is about 100 to 2000, but usually from 200 to 1500, and the softening point is of the order of 60 to 150 ⁰ C. It is possible also to use hydrogenated petroleum resins in which hydrogen is added to the double bonds within the unhydrogenated petroleum resin. The softening point of these hydrogenated petroleum resins is normally of the

order of 90 to 130 ⁰ C. These hydrogenated petroleum resins and uπhydrogenated petroleum resins are components which function as structural materials in the binder composition.

Preferred thermoplastic elastomers are linear or branched block copolymers in which the terminal segments are polystyrene segments, and the rubber constituent segments are segments such as polybutadiene or polyisoprene . As examples of such thermoplastic elastomers, mention may be made of SBS {styrene-butadiene- styrene block copolymer) and SIS (styrene™ isoprene styrene block coplymer) . These are components which, as well as functioning as structural materials, impart elasticity to the binder composition.

Hydrogenated thermoplastic elastomers have hydrogen added to the double bonds of the diene blocks within the molecules of the unhydrogenated thermoplastic elastomer. As well as functioning as structural materials they impart elasticity to the binder composition.

Also, provided the hydrogenated thermoplastic elastomers incorporated in the binder composition of this invention have a hydrogenation rate of at least 95%, there is no special restriction on their type, but it is preferable if they are linear or branched block copolymers in which the terminal segments are polystyrene segments, and the rubber constituent segments are segments such as polyethylene or polybutylene which do not contain double bonds. As examples of such hydrogenated thermoplastic elastomers, mention may be made of SEBS (styrene-ethylene- butylene-styrene block copolymer) , SEPS (styrene-ethylene- propylene-styrene block copolymer) . Also, it is more preferable in these block copolymers if the molecular

weight is not less than 50000, the HFR (melt flow rate) (200 ⁰ C, 5 kg) is not more than 10 g/τnin, the polystyrene content is 10 to 50% by mass, and the specific gravity is at least 0.9. Further, it is possible to incorporate various additives such as lubricating oils in the binder composition of this invention in order to regulate the viscosity or improve transparency and so on.

The binder composition of this invention as described above is no more than a single example and is not limited to this. There is no restriction on a petroleum-based solvent-extracted oil being included, and it is possible, for example, to replace this with a lubricating oil mineral oil. Naturally it is also possible to use any known binder compositions. For example, as binder compositions suitable for this invention, it is possible to incorporate organic compounds having hydroxyl groups into, for example, the binder composition of JP Hll-349816, the binder composition of JP 2001-172469, the binder composition of JP 2007-270042 and the pavement binder composition of JP Hll-286654, so as to regulate the hydroxyl number to be at least 1 mgKOH/g.

Next, a detailed explanation will be given below of a method of actually effecting road paving by using the binder composition of this invention comprised as described above.

First the binder composition of the invention is prepared. At this point, an organic compound having hydroxyl groups is incorporated in asphalt binders as described above or a binder composition which is an ordinary asphalt binder substitute comprised of petroleum- based solvent -extracted oils and so on. At this point it is

preferable to effect stirring for about 30 minutes by means of a mixer while heating to about 150 ⁰ C. The amount of organic compound having hydroxyl groups added at this point has to be regulated so that the hydroxyl number of the obtained binder composition of the invention becomes at least 1 mgKOH/g. The method of measuring the hydroxyl number here is, as described above, based on JIS K 1557-1.

Next, the binder composition of this invention is irradiated with electromagnetic waves by means of an electromagnetic wave radiation apparatus. The frequency of this electromagnetic wave radiation can be any frequency, but it may be for example 2450 MHZ similar to an ordinary electromagnetic oven. By irradiating the binder composition of this invention with electromagnetic waves, it is possible to heat it dielectrically, and it is possible to heat it almost uniformly overall to about 150 ⁰ C to 200 ⁰ C so as to fluidise it and improve its flow characteristics.

Then, in similar fashion to road paving as carried out hitherto, the fluidised binder composition of this invention is mixed with aggregate regulated to the requisite particle size, to produce an asphalt mixture. This asphalt mixture is conveyed to the roadway to be paved, spread on the roadway and compacted down by means of a road roller or the like to give a finished road surface. It is also possible to create road paving as follows in this invention. The binder composition of this invention is conveyed to the roadway. The binder of this invention is then irradiated with electromagnetic waves by means of an electromagnetic wave radiation apparatus. By irradiating the binder composition of this invention with electromagnetic waves, it is possible to heat it

dielectrically and it is possible to heat it almost uniformly overall to about 150 ⁰ C to 200 ⁰ C so as to fluidise it and improve its flow characteristics. Next, suitable aggregate is spread on to the fluidised binder composition of this invention and the road surface can be finished by compacting it down by means of a road roller or the like.

At this point, it is also possible to place the binder composition of this invention in a radio- frequency heating apparatus such as illustrated in JP H8-13414, and to convey it to the site while heating it dielectrically and then spreading it on the roadway.

It is also possible to convey the binder composition of this invention to the roadway to be paved, to spread aggregate thereon and then irradiate it with electromagnetic waves by means of an electromagnetic wave radiation apparatus, to thus heat the binder composition of this invention, and then to finish the road surface by compacting down the fluidised binder composition of this invention and the aggregate by means of a road roller or the like.

Further, in this invention it is possible to finish a road surface by irradiating a mixture of the binder composition of this invention spread on the roadway and the aggregate, heating this to a uniform temperature and compacting it down by means of a road roller or the like, and then cooling it. In this case, it is also possible for example to effect radio-frequency heating of the binder composition spread on the roadway by using the induction heating apparatus described in JP H10-266114. Further, in this invention it is possible to mix the binder composition of this invention and the aggregate in

advance, and then to store it as normal temperatures and to make it pourable by heating it by radio-frequency heating at the time of road paving, to convey it to the paving site and to spread it on the roadway by road paving methods of the prior art . Alternatively, it is possible to convey a mixture of the binder composition of this invention and aggregate stored at ordinary temperatures, to apply it to the roadway and then to make it flowable by radio- frequency heating, and to spread it on the roadway by road paving methods from the prior art .

Whereas the methods of heating by using heating apparatus such as heaters and gas burners as in the prior art rely on the temperature rise due to convection and thermal conduction, with the method of radio- frequency heating which is used in this invention it is possible to promote a temperature rise by heat generation of the binder composition of this invention itself,

In concrete terms, the molecules within the binder composition of this invention irradiated with electromagnetic waves at about 2450 MHz vibrate on the basis of these electromagnetic waves. In other words, the molecules in the binder composition of this invention are aligned on the basis of the plus charge and the minus charge of the electromagnetic waves. Given that these electromagnetic waves are constituted of short waves of

2450 MHz, the intervals in the time they vibrate to plus or minus is extremely short. For this reason, the direction of alignment of the molecules in the binder composition of this invention changes violently within a short space of time, and as a result frictional heat arises between the molecules, so that it is possible to effect generation of

heat in the binder composition of this invention itself. In other words, by irradiating the binder composition of this invention with electromagnetic waves, it is possible to agitate the molecules inside it and to heat it by means of the frictional heat from the molecules acting in concert.

In particular, the binder composition of this invention contains an organic compound having hydroxy1 groups. Because of this, it is possible to make the changes in alignment between molecules caused by the electromagnetic wave radiation even more violent by virtue of the polarity the hydroxyl groups possess. As a result, it is possible to increase the frictional heat from the molecules by virtue of the presence of these hydroxyl groups . In particular, given that the hydroxyl number of the binder composition of this invention as a whole is regulated so as to be at least 1 mgKOH/g ^" , it becomes possible to impart the necessary polarity to boost the temperature rise by radio-frequency heating when irradiating with electromagnetic waves without the proportion of hydroxyl groups in the binder composition of this invention being too low. Specifically, in the case of irradiation with electromagnetic waves which comprise the frequencies as described above, it is possible to heat the binder composition of this invention more than approximately 4 ⁰ C higher than in binder compositions where no organic compound having hydroxyl groups has been added.

In other words, in the case of the same irradiation with electromagnetic waves, the binder composition of this invention can improve the heating efficiency in comparison with binder compositions where no organic compound having

hydroxyl groups has been added. Also, with this radio- frequency heating, the binder composition of this invention itself is made to generate heat, and since there is no need to transfer heat such as with the heating apparatus of the prior art using burners and the like, a rapid temperature rise of the whole of the substance being heated becomes possible, and a uniformly raised temperature of the substance being heated as a whole is also possible. Also, in the case of this irradiation with electromagnetic waves, given that it is possible to raise the temperature of the binder composition of this invention itself, as the substance being heated, the surplus energy which heats heating bodies and the environment is not required, and so the overall energy efficiency can be improved.

Further, given that this irradiation with electromagnetic waves must use electricity as the energy source, it may be possible to reduce the emission of CO ₂ . Also, since it is possible to implement uniform heating of the binder composition of this invention, it is possible to eliminate problems, as in heating methods that use heating apparatus such as gas burners, where there is a large differential between the heated portion and the portion separated from the heated portion. As a result, it becomes possible to suppress the production of noxious odours due to heating the heated portion to more than is necessary to be able to raise the temperature of the portion separated from the heated portion. It also becomes possible to implement heating of the bright-colour paving and asphalt binders and bright-colour binders which are kinder to the environment .

Examples

The effect of the invention is explained below by means of Examples and Comparative Examples.

For the existing bright-colour binder composition it is possible to use, for example, Binder Composition 1 as disclosed in JP Hll-349816. This Binder Composition 1 is constituted from a petroleum-based solvent-extracted oil, a petroleum resin, a thermoplastic elastomer and an anti- peeling additive. Petroleum-based solvent extracted oil: Oil wherein the viscosity at 100 °C is 68 centistokes, the aromatic component is 33% by weight, the naphthene component is 26% by weight, the paraffin component is 41% by weight and the flash point is 254 ⁰ C. This petroleum-based solvent extracted oil forms 63.4% content by weight.

Petroleum resin: Petroleum resin with C9 residue as the raw material, the characteristics of which are that the softening point is 14Q ^C C, the acid number is not more than 0.1 (mgKOH : JIS K0070) , the bromine number is 25 (g : JIS K2543) , and the average molecular weight is approximately 1000 (GPC method, polyethylene conversion) . This petroleum resin forms 32.1% content by weight.

Thermoplastic elastomer: Thermoplastic elastomer comprising styrene-butadiene-styrene block copolymer. Its characteristics are that the specific gravity is 0.94, hardness (Shore A) is 72, and the solution viscosity is 4000 cps {polymer concentration 25 wt% toluene solution, 25°C} . This thermoplastic elastomer forms 4.5% content by weight . Anti-peeling agent: A mixture comprised of 7% by weight of monomer acid of 18 hydrocarbons, 76% by weight of

dimer acid of 36 hydrocarbons and 7% by weight of trimer acid of 54 hydrocarbons wherein the acid number is 190 (mgKOH : JIS K0070) and the iodine number is 110. The average molecular weight is approximately 590. This anti- peeling agent forms 0.3% content by weight.

For the existing bright- colour binder composition it is also possible to use, for example, Binder Composition 2 as disclosed in JP 2001-172469.

This Binder Composition 2 is constituted from a petroleum-based solvent -extracted oil, a petroleum resin, a thermoplastic elastomer and an anti-peeling additive.

Petroleum-based solvent extracted oil: Oil wherein the viscosity at 100 ⁰ C is 68 cps, the aromatic component is 33% by weight, the naphthen-e component is 26% by weight, the paraffin component is 41% by weight and the flash point is 254 ⁰ C. This petroleum-based solvent extracted oil forms 49.7% content by weight.

Hydrogenated petroleum resin: Hydrogenate of a petroleum resin with dicyclopentadiene (DCPD) as the raw material, wherein the softening point is 130 ⁰ C, the bromine number is 3 (g : JIS K2543) , and the average molecular weight is approximately 500 (GPC method, polyethylene conversion) . The hydrogenated petroleum resin forms 47% content by weight. Hydrogenated thermoplastic elastomer: Thermoplastic elastomer comprising styrene-ethylene-butylene-styrene block copolymer. Its characteristics are that the specific gravity is 0.91, hardness (Shore A) is 76, and the solution viscosity is 1000 cps (polymer concentration 10 wt% toluene solution, 25 ⁰ C) . The hydrogenated thermoplastic elastomer forms 3% content by weight.

Anti-peeling agent: A mixture comprised of 7% by weight of monomer acid of 18 hydrocarbons, 76% by weight of dimer acid of 36 hydrocarbons and 7% by weight of trlmer acid of 54 hydrocarbons wherein the acid number is 190 (mgKOH : JIS K0070) and the iodine number is 110. The average molecular weight is approximately 590. The anti- peeling agent forms 0.3% content by weight.

For the existing bright-colour binder composition it is also possible to use, for example, Binder Composition 3 as disclosed in JP 3727829.

Binder Composition 3 is a mixture which hot melts at 170 to 180 ^D C and is comprised of 37.1 parts by weight of a paraffin-based process oil {made by Idemitsu Kosan Ltd. , trade name PW-380) , 58.0 parts by weight of a hydrogenated petroleum resin (made by Idemitsu Petrochemical Co. Ltd., trade name I-MARV P-125) and 5.0 parts by weight of hydrogenated styrenic thermoplastic elastomer (SEBS) (made by Asahi Kasei Kogyo Ltd., trade name Tuftec H1041) .

For the organic compound having hydroxyl groups it is possible to use Additives 4 to 7.

Additive 4: Glycerol (C ₃ H ₈ O ₃ ), molecular weight 92.1, hydroxyl number 1820 mgKOH/g.

Additive 5: Polyether with molecular weight approximately 850 and hydroxyl number 380 mgKOH/g. (Polyether O-850 made by Toho Chemical Industry Co. Ltd.)

Additive 6: Polyether with molecular weight approximately 500 and hydroxyl number 400 mgKOH/g. (Polyether PE-555 made by Toho Chemical Industry Co. Ltd.)

Additive 7 : Polyether with molecular weight approximately 1000 and hydroxyl number 250 mgKOH/g.

(Polyether OB-1010 made by Toho Chemical Industry Co. Ltd.)

The respective Additives 4 to 7 were mixed with the above mentioned binder compositions 1 to 3 for 30 minutes at 15O ⁰ C using a homomixer. 3Og of the mixed sample was placed in a 50 ml beaker and irradiated with 2450 MHz electromagnetic waves for 180 seconds using an electronic oven of 500W high frequency output. The hydroxyl number before and after heating was measured in accordance with JIS K 1557-1. The raised temperature due to radiation of the electromagnetic waves was the result of measuring the difference in the temperature before heating and the temperature after heating by using a radiation thermometer (radiation rate 0.95) .

The formulations and hydroxyl numbers of Examples 1 to 8 and Comparative Examples 1 to 3 are given in Table 1. Table 1 also shows the relationships between hydroxyl number (mgKOH/g) and raised temperature ( ⁰ C) for Examples 1 to 8 and Comparative Examples 1 to 3. The raised temperatures in Table 1 are divided into those which take the temperature before heating as the criterion and those which take the raised temperature of Comparative Example 2 as the criterion.

Table 1

As shown in Table 1, the raised temperature for Comparative Examples 1 to 3 was about 10 ⁰ C in each case. In contrast, in Examples 1 to 8 the raised temperature was at least 14.7 ⁰ C in each case. The temperature differential, taking Comparative Example 2 as the criterion, for Examples 1 to 8 was not less than 4.5 ⁰ C. Because of this, provided the hydroxyl number is at least 1 mgKOH/g, there will be a temperature rise of at least 4.5°C and so the heating efficiency can be improved. Also, Examples 2 and 3 each had a hydroxyl number under 5 mgKOH/g and the temperature rise was small. The difference in raised temperature, taking Comparative Example 2 as the criterion, was less than 6 ⁰ C. In Examples 1, 5 and 7, where the hydroxyl number was at least 15 mgKOH/g in each case, the temperature rise was large, and in particular the difference in raised temperature was at least 20 ⁰ C or more, taking Comparative Example 2 as the criterion.

For this reason, it can be seen that a higher hydroxyl number is best to effect an improvement in raised temperature .

In further Examples and a Comparative Example, the binder is an asphalt binder. The existing straight asphalt may be, for example, the petroleum asphalts 60 to 80 shown in JIS K 2207 and manufactured by Showa Yokkaichi Sekiyu Ltd.

For the organic compound having hydroxyl groups it is possible to use Additives 4 to 7 as described above.

The respective Additives 4 to 7 were mixed with the above mentioned straight asphalt for 30 minutes at 150 ⁰ C using a homomixer. 30g of the mixed sample was placed in a

50 ml beaker and irradiated with 2450 MHz electromagnetic waves for 180 seconds using an electronic oven of 500W high frequency output . The hydroxyl number before and after heating was measured in accordance with JIS K 1557-1. The raised temperature rise due to radiation of the electromagnetic waves was the result of measuring the difference in the temperature before heating and the temperature after heating by using a radiation thermometer (radiation rate 0.95) . The formulations and hydroxyl numbers of Examples 9 to

19 and Comparative Example 4 are given in Table 2. Table 2 also shows the relationships between hydroxyl number (mgKOH/g) and raised temperature ( ⁰ C) for Examples 9 to 19 and Comparative Example 4. The raised temperatures in Table 2 are divided into those which take the temperature before heating as the criterion and those which take the raised temperature of the Comparative Example as the criterion.

Table 2

As shown in Table 2 , the raised temperature for comparative example 4 was about 9.8 ⁰ C. In contrast, in Examples 9 to 19 the raised temperature was at least 14.1°C in each case. The temperature difference, taking the comparative example as the criterion, for Examples 9 to 19 was not less than 4.3 ⁰ C. Because of this, provided the hydroxyl number is at least 1 mgKOH/g, there will be a temperature rise of at least 4.3 ⁰ C and so the heating efficiency can be improved. The reason why significance is attached to a temperature rise of at least 4.3 ⁰ C is that when a temperature difference of more than approximately 4 ⁰ C, which is 10 times the experimental error of 0.4 ⁰ C, is produced, the heating efficiency is deemed especially good. However, it is not strictly necessary for the hydroxyl value to be not less than 1.14 mgKOH/g, and provided it is at least 1 mgKOH/g, it is believed that a temperature rise that can virtually be expected will result.

Also, Examples 12 and 13 each had a hydroxyl number under 5 mgKOH/g and the temperature rise was small. The difference in raised temperature, taking the comparative example as the criterion, was less than 6 ⁰ C and the temperature rise was lower than for the other examples. In Examples 9 to 11, 15, 16 and 18, where the hydroxyl number was at least 15 mgKOH/g in each case, the temperature rise was large, and in particular the difference in raised temperature was at least 20 ⁰ C, taking the comparative example as the criterion.

For this reason, it can be seen that a higher hydroxyl number is best to effect an improvement in raised temperature .