JP2006176599A - Asphalt-modifying material, asphalt mixture containing the same and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plant-mixing type asphalt-modifying material which exhibits excellent compatibility with asphalt and excellent modifying effects. <P>SOLUTION: The asphalt-modifying material is obtained by mixing under heating 50-100 pts.wt. of a mineral oil having a condensed polycyclic aromatic (PCA) content of less than 3 mass%, a kinematic viscosity at 60°C of 20-200 mm<SP>2</SP>/s and an aromatic content (% CA) of 5-25 and 10-50 pts.wt. of a synthetic wax having a viscosity at 140°C of 10-70 mPa s and a weight-average molecular weight of 1×10<SP>3</SP>-3×10<SP>3</SP>with 100 pts.wt. of a polymer, and has a viscosity at 150°C of 150×10<SP>3</SP>-350×10<SP>3</SP>mPa s, a weight-average molecular weight (Mw) of 10×10<SP>3</SP>-100×10<SP>3</SP>, a melt flow rate (190°C, 21.2 N) of 20-150 g/10 min and a softening point of 90-130°C. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an asphalt modifier, an asphalt mixture and a method for producing the same.

  In general, asphalt used for asphalt pavement softens and flows at high temperatures. Therefore, particularly when the road surface in summer becomes hot, there is a problem that the surface of the pavement is plastically deformed due to the traffic load received from the tires, and rutting is caused. On the other hand, asphalt becomes hard and brittle at low temperatures, and therefore has the disadvantage that cracks occur on the surface of the pavement, especially when the road surface in winter becomes cold. In addition, problems such as aggregate scattering and pavement surface wear have arisen due to an increase in traffic and an increase in the size of vehicles, and further improvements are required for these performances.

  Therefore, as a method for solving these problems, modified I-type and modified II-type modified by adding polymer such as rubber such as SBR and thermoplastic elastomer such as SBS to the asphalt. Asphalt was developed and some effect was seen. However, in recent years, there has been a demand for longer pavement life, and there is a need to further improve the durability of conventional modified asphalt for major trunk roads with more severe traffic environments and snowy and cold regions with severe weather conditions. .

  In recent years, high-value-added pavement is becoming widespread, and high-performance pavement and noise-reduction pavement use modified asphalt called high-viscosity asphalt with improved viscosity compared to the modified asphalt. It is becoming. However, even in these pavements, pavement destruction such as rutting, cracking, aggregate scattering, and wear has occurred, and further improvement in durability is still required.

  It is known that the performance of these modified asphalts is greatly influenced by the compatibility between the asphalt and the polymer (modifier). It is necessary to uniformly melt and disperse the polymer (modifier). However, the compatibility of asphalt and polymer (modifier) is not always good, and for uniform dispersion, premixing using special equipment such as a high shear mixer for 1 hour or more, usually 2-8 It took time to stir and mix, requiring a lot of time and labor, dedicated equipment, and a lot of energy to operate the equipment.

On the other hand, when mixing asphalt and aggregate in an asphalt mixture plant, there is also a method of directly modifying the asphalt by adding a polymer (modifier) to the mixer, so-called plant mix method. It exists from the past. Since the mixing in the plant mix method is usually about 1 to 5 minutes, it is more difficult than the premix method to uniformly disperse the polymer (modifier). As a method for improving the melt dispersibility of polymer polymers (modifiers), a method of preparing a composition in which a petroleum resin and heavy oil are blended in advance with a polymer polymer and adding this composition to asphalt (patent) Documents 1 to 3) propose a method (Patent Document 4) in which a composition in which a polymer is blended with asphalt in advance is prepared, and this composition is added to asphalt.
However, none of the above conventional methods has obtained a sufficient reforming effect for mixing the modifier and asphalt, and the uniform dispersion of the modifier and asphalt, particularly in the plant mix system, in a short time. At present, the uniform dispersibility is not sufficient, so that the reforming effect by the reforming material is not sufficiently exhibited.

JP-A-5-295273 JP-A-9-25416 JP 2001-019852 A JP 2000-290507 A

Here, the polymer that is most difficult to melt and disperse in asphalts is pretreated in a form that is easy to melt and disperse, and because the treatment itself uses petroleum resin and heavy oil, the treatment becomes easy. The said method of patent documents 1-3 is a preferable method.
On the other hand, despite the fact that synthetic wax is inexpensive, there are few examples of polymeric polymer modifiers.

In view of such circumstances, an object of the present invention is to provide a plant mix type asphalt modifier excellent in compatibility with asphalt and a reforming effect.
That is, an object is to provide a novel asphalt modifier using a synthetic wax which is inexpensive.

  As a result of diligent research, the present inventors have found that an asphalt modifier having a specific property obtained by blending a specific mineral oil with a polymer polymer and a synthetic wax can solve the above-mentioned problems, and has completed the present invention. It is what.

That is, in the first aspect of the present invention, the condensed polycyclic aromatic (PCA) is less than 3% by mass, the kinematic viscosity at 60 ° C. is 20 to 200 mm ² / s, the aromatic content (%) with respect to 100 parts by weight of the polymer. 50 to 100 parts by weight of mineral oil having a CA) of 5 to 25%, 10 to 50 parts by weight of synthetic wax having a viscosity at 140 ° C. of 10 to 70 mPa · s and a weight average molecular weight of 1 × 10 ^{3 to} 3 × 10 ³ The viscosity at 150 ° C. obtained is 150 × 10 ^{3 to} 350 × 10 ³ mPa · s, the weight average molecular weight (Mw) is 10 × 10 ^{3 to} 100 × 10 ³ , and the melt flow rate (190 ° C., 21.2 N) is It is an invention of an asphalt modifier characterized by a 20 to 150 g / 10 min softening point of 90 to 130 ° C.

  The second aspect of the present invention is the asphalt modifier according to claim 1, wherein the asphalt mixture is used in an asphalt mixture plant with respect to aggregate, asphalt in an amount of 4 to 10% by mass, and 100 parts by weight of asphalt. 3 to 40 parts by weight of an asphalt mixture obtained by heating and mixing.

  The third aspect of the present invention is the asphalt modifying material according to claim 1, wherein the asphalt mixture plant is an aggregate, an asphalt in an amount of 4 to 10% by mass with respect to the aggregate, and 100 parts by weight of the asphalt. This is a method for producing an asphalt mixture comprising heating and mixing 3 to 40 parts by weight.

The asphalt modifier of the present invention is suitable as a plant mix type asphalt modifier because of its excellent compatibility with asphalt and its modification effect.
A novel asphalt modifier containing synthetic wax is provided, which is compared to conventional modifiers in which a polymer is treated with petroleum resin and heavy oil, It is an asphalt modifier with excellent final asphalt properties.

Hereinafter, the present invention will be described in detail.
(Composition of asphalt modifier)
The asphalt modifier of the present invention is obtained by blending 50 to 100 parts by weight of mineral oil having predetermined properties described later and 10 to 50 parts by weight of synthetic wax having predetermined properties described later with respect to 100 parts by weight of the polymer. It is. When the blending amount of the mineral oil is less than 50 parts by weight with respect to 100 parts by weight of the polymer, the compatibility of the polymer cannot be sufficiently improved and cannot be quickly and uniformly mixed in the asphalt. It is not preferable. On the other hand, when the blending amount of the mineral oil exceeds 100 parts by weight, the blending ratio of the high molecular polymer in the asphalt modifier is small, so that the asphalt reforming effect is small, which is not preferable. In addition, when the blending amount of the synthetic wax is less than 10 parts by weight with respect to 100 parts by weight of the high molecular polymer, the viscosity of the modifier is increased, which causes a problem when the modifier is used. On the other hand, when the compounding amount of the synthetic wax exceeds 50 parts by weight, the modifier is sticky and inferior in handleability, and cannot serve as an asphalt modifier sufficiently.

(Polymer polymer)
As the polymer used in the asphalt modifier of the present invention, any polymer can be used as long as it is used for the asphalt modifier. Preferably, a thermoplastic elastomer such as styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), styrene-ethylene-butylene-styrene block copolymer (SEBS) is suitable. These thermoplastic elastomers can be used alone or in combination of two or more. Of these, a styrene-butadiene-styrene block copolymer (SBS) is more preferably used.
Preferable styrene-butadiene-styrene block copolymers are those having a styrene content of 5 to 40% by mass and a weight average molecular weight (Mw) of 50,000 to 400,000. The lower limit of the styrene content is preferably 5% by mass or more, more preferably 10% by mass or more, and still more preferably 15% by mass from the viewpoint of preventing the asphalt modification effect added by the asphalt modifier from being expected. On the other hand, the upper limit is preferably 40% by mass or less, more preferably 30% by mass or less, and still more preferably 25% in order to improve the difficulty of forming the asphalt modifier due to the high melting temperature. It is below mass%. Further, the lower limit of the weight average molecular weight is preferably 50,000 or more, more preferably 100,000 or more, and further preferably 150,000 or more in order to exert the modification effect of the asphalt modifier. On the other hand, the upper limit is preferably 400,000 or less, more preferably 300,000 or less, and even more preferably 200,000 or less in order to prevent the melting temperature from becoming high and making it difficult to form the asphalt modifier.

(Mineral oil)
The mineral oil used in the asphalt modifier of the present invention needs to have a condensed polycyclic aromatic (PCA) content of less than 3% by mass. When PCA is 3% by mass or more, the load on the environment and the human body may increase, such being undesirable. For this reason, PCA is preferably less than 2.8% by mass, and more preferably less than 2.6% by mass.
Here, the term condensed polycyclic aromatic content and (PCA) is, IP346 / 92 of "The Institute of Petroleum""Determination of polycyclic aromatics in unused lubricating base oils and asphaltene free petroleum fractions - Dimethyl sulphoxide extraction refractive index method" It means the content (% by mass) of the polycyclic aromatic hydrocarbon compound measured according to the method.

Further, the kinematic viscosity at 60 ° C. of the mineral oil used for the asphalt modifier of the present invention needs to be ²⁰ to 200 mm ² / s. The lower limit of the kinematic viscosity at 60 ° C. is required to be 20 mm ² / s or more, preferably 30 mm ² / s or more, and more preferably 50 mm ² / s or more, from the handling deterioration point due to adhesion between the modifiers. It is. On the other hand, the upper limit from the viewpoint of compatibility with the high polymer is required to be less 200 mm ² / s, preferably not more than 180 mm ² / s, more preferably at most 150 mm ² / s.
The kinematic viscosity at 60 ° C. here means the kinematic viscosity (mm ² / s) measured by JIS K2283 “Crude oil and petroleum products—Kinematic viscosity test method and viscosity index calculation method”.

In addition, the aromatic content (% CA) of the mineral oil used for the asphalt modifier of the present invention needs to be 5 to 25% CA. The lower limit of the aromatic content is required to be 5% CA or more, preferably 8% CA or more, more preferably 10% CA or more from the viewpoint of the meltability / dispersibility of the polymer in mineral oil. It is necessary. On the other hand, the upper limit is required to be 25% CA or less, preferably 23% CA or less, more preferably 20% CA or less, from the viewpoint of improving the strength development of the polymer in the asphalt modifier.
Here, the aromatic content (% CA) refers to ASTM D3238 “Standard Test Method for Calculation of Carbon Distribution and Structural Group of Petroleum Oil M It means the percentage (%) of the number of aromatic ring carbons.

  The kind of mineral oil used for the asphalt modifier of the present invention is not particularly limited as long as the above properties are satisfied. For example, Pennsylvania crude oil, Minas crude oil, Daqing crude oil, etc. Atmospheric residual oil obtained by atmospheric distillation of mixed base crude oil such as crude oil, foot crude oil, Kuwait crude oil, Lattaway crude oil, Allian crude oil, Eosin crude oil, Solish crude oil, etc. is distilled under reduced pressure and the obtained fraction is used. It is preferable to do. The fraction obtained from the reduced-pressure distillation step is obtained by solvent removal such as propane removal, solvent extraction represented by furfural extraction, MEK dewaxing, etc., which removes wax using MEK (methyl ethyl ketone). It is more preferable to purify by appropriately combining treatments such as representative solvent dewaxing, hydrocracking solvent dewaxing, catalytic dewaxing, hydrorefining, sulfuric acid washing, and clay treatment. In particular, the lubricating oil fraction obtained by distilling crude oil under reduced pressure is further subjected to hydrorefining and MEK removal of the raffinate obtained by furfural extraction using a furfural to remove aromatic compounds and resins from the lubricating oil fraction. Purified raffinate obtained by combining wax, etc., PDA extract obtained by propane removal for the purpose of extracting lubricating oil fraction from vacuum distillation residue oil, obtained by furfural extraction of PDA extract PDA furfural extract, high-viscosity high-grade lubricating oil component (bright stock) obtained by processing PDA furfural raffinate obtained by furfural extraction of PDA extract in combination with MEK dewaxing and hydrorefining, etc. are suitable Used.

The crude oil used in producing the mineral oil used for the asphalt modifier of the present invention is selected according to the type of mineral oil required, but it is a paraffin base crude oil such as Pennsylvania crude oil, Minas crude oil, Daqing crude oil, California crude oil, Texas Crude oil, naphthenic crude oil such as Venezuela crude oil, mid-continuous crude oil, Arabian crude oil, Gucci Saran crude oil, Kafuji crude oil, Maya crude oil, neutral zone special crude oil, Foot crude oil, Kuwait crude oil, Lataway crude oil, Allian crude oil, Eosin crude oil, Solish crude oil, etc. A mixed base crude oil or the like can be preferably used.
The mineral oil having the above physical properties is available as a commercial product as shown in Examples and the like described later.

(Synthetic wax)
The viscosity at 140 ° C. of the synthetic wax used for the asphalt modifier of the present invention needs to be 10 to 70 mPa · s. The lower limit of the viscosity at 140 ° C. is preferably 20 mPa · s or more, more preferably 30 mPa · s or more, from the viewpoint of preventing blocking due to stickiness of the molded asphalt modifier. On the other hand, the upper limit is preferably 60 mPa · s or less, and more preferably 50 mPa · s or less, from the viewpoint of ease of forming the asphalt modifier.
The viscosity at 140 ° C. here refers to a value measured according to JIS K7117 “Method of measuring viscosity with a rotational viscometer”.

Moreover, the weight average molecular weight (Mw) of the synthetic wax used for the asphalt modifier of the present invention needs to be 1 × 10 ^{3 to} 3 × 10 ³ . The lower limit of the weight average molecular weight is preferably 1.2 × 10 ³ or more and more preferably 1.4 × 10 ³ or more from the viewpoint of preventing stickiness of the molded asphalt modifier. On the other hand, the upper limit is preferably 2.8 × 10 ³ or less, more preferably 2.5 × 10 ³ or less, from the viewpoint of ease of forming the asphalt modifier.
The weight average molecular weight here refers to the value of the weight average molecular weight (Mw) determined by gel permeation chromatography (GPC).

The kind of the synthetic wax used for the asphalt modifier of the present invention is not particularly limited as long as the above properties are satisfied, but a polyolefin wax, Fischer-Tropsch (manufactured by a general polymerization type, a modified type, a decomposition type, etc.) Fischer-Tropsch wax (FT wax) obtained by Fischer-Tropsch synthesis.
The polyolefin wax can be obtained, for example, by a production method in which mainly an olefin monomer is used as a raw material and polymerized with a radical catalyst, a Ziegler-Natta catalyst, a metallocene catalyst, or the like, or a method in which the polymer is decomposed. Typical examples include polyethylene wax and polypropylene wax. A modified polyolefin wax obtained by processing or modifying a polyolefin wax by chemical or physical means can be particularly preferably used in order to ensure sufficient compatibility of the polymer.
The FT wax can be produced, for example, by synthesizing (FT synthesis) carbon monoxide and hydrogen generated by gasification of natural gas or petroleum heavy residual oil using an FT catalyst.
The synthetic wax of the present invention can contain a small amount of a polar compound such as an oxygen-containing compound as necessary. Synthetic waxes having various physical properties are available because of synthesis, and therefore, the synthetic waxes of the present invention having the above physical properties can be easily obtained as commercial products as shown in Examples and the like described later.

(Properties of asphalt modifier)
The viscosity at 150 ° C. of the asphalt modifier of the present invention needs to be 150 × 10 ^{3 to} 350 × 10 ³ mPa · s. The lower limit of the viscosity at 150 ° C. is preferably 120 × 10 ³ or more, and more preferably 130 × 10 ³ or more, from the viewpoint of improving the dynamic stability of the asphalt mixture. On the other hand, the upper limit is preferably 330 × 10 ³ or less, and more preferably 310 × 10 ³ or less, from the viewpoint of improving the melt dispersion of the modifying material in the asphalt mixture plant.
The viscosity at 150 ° C. here refers to a value measured according to JIS K7117 “Method of measuring viscosity with a rotational viscometer”.

The weight average molecular weight (Mw) of the asphalt modifier of the present invention needs to be 10 × 10 ^{3 to} 100 × 10 ³ . The lower limit of the weight average molecular weight is preferably 30 × 10 ³ or more, and more preferably 50 × 10 ³ or more, from the viewpoint of improving the dynamic stability of the asphalt mixture. On the other hand, the upper limit is preferably 90 × 10 ³ or less, and more preferably 80 × 10 ³ or less, from the viewpoint of improving the melt dispersibility of the modifying material in the asphalt mixture plant.
The weight average molecular weight here refers to the value of the weight average molecular weight (Mw) determined by gel permeation chromatography (GPC).

The melt flow rate (190 ° C., 21.2 N) of the asphalt modifier of the present invention needs to be 20 to 150 g / 10 minutes. The lower limit of the melt flow rate is preferably 20 or more, more preferably 30 or more, from the viewpoint of improving the dynamic stability of the asphalt mixture. On the other hand, the upper limit is preferably 130 or less, and more preferably 110 or less, from the viewpoint of improving the melt dispersibility of the modifying material in the asphalt mixture plant.
Here, the melt flow rate (190 ° C., 21.2 N) means a value at a test temperature of 190 ° C. and a load of 21.2 N measured by ASTM D1238 “Test Method for Flow Rates of Thermoplastics by Extraction Plasometer”. . In other words, the flow rate for 10 minutes when extruding an asphalt modifier melted at a constant temperature of 190 ° C. from a circular die having a specified length and diameter at a constant load of 21.2 N is a numerical value expressed in grams.

The softening point of the asphalt modifier of the present invention needs to be 90 to 130 ° C. The lower limit of the softening point is preferably 100 ° C. or higher and more preferably 105 ° C. or higher from the viewpoint of improving the dynamic stability of the asphalt mixture. On the other hand, the upper limit is preferably 125 ° C. or lower, more preferably 120 ° C. or lower, from the viewpoint of improving the melt dispersibility of the modifying material in the asphalt mixture plant.
The softening point as used herein is a value measured by JIS K2207 “Petroleum Asphalt—Softening Point Test Method”.

(Manufacturing method of asphalt modifier)
The production method of the asphalt modifier of the present invention is not particularly limited as long as the blending ratio, properties, and the like satisfy the above ranges. Usually, polymer polymers, mineral oils and synthetic waxes are mixed using a mixer such as a heat melting kettle, high shear mixer, Banbury mixer, Hensyl mixer, etc., then pelletizer, extrusion molding machine, processing molding machine, press molding It can be molded by a machine. In addition, the shape of the asphalt modifier of the present invention is not particularly limited, and can be used in any shape. For example, a pellet shape, a plate shape, a string shape, a block shape, and the like can be mentioned. In consideration of the mixing property in the plant, a pellet shape is preferable. Pelletization of asphalt modifier is performed by, for example, heating and mixing a polymer and petroleum resin at 150 to 180 ° C. for 3 to 10 minutes, and then extruding into a string using an extruder and then cutting with a pelletizer or the like. Can be achieved. When the size of the pellet is 1 to 50 mm, preferably 1 to 20 mm, and more preferably 1 to 10 mm, the pellet can be rapidly melted and dispersed even in plant mixing.

(Method for producing asphalt mixture)
The asphalt modifying material of the present invention is blended and mixed with asphalt together with aggregates, if necessary, and used for road pavement in the form of an asphalt mixture.
It is preferable to produce the asphalt mixture of the present invention to be used for the road pavement and the like by the following method.
That is, in road pavement, asphalt and aggregate are mixed in an asphalt mixture plant, and the resulting asphalt mixture is applied to road pavement. The asphalt mixture plant has a short mixing time because of on-site construction, but the asphalt modifier of the present invention sufficiently melts and disperses even in a mixed state in such a mixture plant.
Specifically, such mixing is performed in the asphalt mixture plant in the amount of asphalt equivalent to 4 to 10% by mass of the input aggregate and 100 parts by weight of the input asphalt. An asphalt mixture can be produced by adding 3 to 40 parts by weight of the asphalt modifier of the invention and heating and mixing.
More specifically, in the asphalt mixture plant, the aggregate heated to 160 to 200 ° C. is charged into the mixer, and then the asphalt heated to 150 to 190 ° C. is 4 to 10% by mass of the aggregate. The amount corresponding to is added and mixed. Then, the target asphalt mixture can be manufactured by adding 3 to 40 parts by weight of the above-mentioned asphalt modifier to 100 parts by weight of the input asphalts.

Here, when the addition amount of the asphalt modifier is less than 3 parts by weight relative to 100 parts by weight of the input asphalt, a satisfactory modification effect cannot be obtained even if the asphalt modifier is added. Preferably, 10 parts by weight or more is more preferable. On the other hand, when the added amount of the asphalt modifier exceeds 40 parts by weight, mixing in the plant becomes difficult and only a non-uniform asphalt mixture can be produced. Therefore, preferably 40 parts by weight or less, more preferably 30 parts by weight or less, More preferably, it is 20 parts by weight or less.
The aggregate used in the asphalt mixture of the present invention is not particularly limited as long as it is used for paving, but is not particularly limited, but crushed stone, sand, gravel and similar steel slag. A granular material such as can be used.
An amount of asphalt corresponding to 4 to 10% by mass of the aggregate is used. If the asphalt is less than 4% by mass, the asphalt construction work is difficult, and if it exceeds 10% by mass, the strength as a paving material is insufficient.

  Moreover, the asphalt used for the asphalt mixture of the present invention is not particularly limited as long as it is used for road paving. For example, various crude oils are subjected to atmospheric distillation equipment and vacuum distillation equipment to remove light components and straight asphalt, which is a semi-solid and solid sticky substance mainly composed of bituminous material, or straight asphalt under normal pressure. Asphalts such as semi-blown asphalt, blown asphalt blown with air at a temperature of 230 to 300 ° C., modified asphalt in which a thermoplastic elastomer or the like is added to straight asphalt, and high viscosity modified asphalt can be used. In particular, asphalt for paved roads is preferred.

  The asphalt modifier of the present invention can be sufficiently compatible even by the plant mix method in an asphalt mixture plant which often has insufficient mixing time as described above. In this respect, it is not inferior to an asphalt modifier formed by blending a conventional petroleum resin and heavy oil in a polymer.

(Other)
Furthermore, as a matter of course, the asphalt modifier of the present invention can be used for the above-mentioned plant mix method and can be used without any problem as a conventional asphalt modifier for premix.
That is, asphalt is put in a 120-180 ° C heating and melting pot, 5-10 parts by mass of the asphalt modifier of the present invention is added, and the mixture is stirred and mixed for 0.5-3 hours to obtain the modified asphalt for premix. Can be manufactured. Moreover, a highly viscous modified asphalt can also be manufactured by selecting arbitrarily the addition amount of an asphalt modifier. The modified asphalt thus obtained is used, for example, as part or all of the asphalt to be charged in the asphalt mixture plant, and is mixed with aggregate to obtain an asphalt mixture.

Hereinafter, the present invention will be specifically described with reference to examples and comparative examples, but the present invention is not limited to these examples.
[Examples 1-8 and Comparative Examples 1-12]
Polymer polymers, mineral oils and synthetic waxes are heated and melted and mixed at 120 to 150 ° C. at the base material types and blending ratios shown in Table 1 and extruded into a string using an extruder, and then a diameter of 3 mm and length with a pelletizer. Asphalt modifiers A to G were manufactured by cutting into pellets of about 4 mm. The physical property values of the obtained asphalt modifiers A to G are also shown in Table 1.
As the polymer, Tafprene T315 (styrene content 20 mass%, weight average molecular weight 150,000) manufactured by Asahi Kasei Co., Ltd. was used.
Further, SNH440 (PCA content 2.4 mass%, 60 ° C. kinematic viscosity 110 mm ² / s, aromatic content (% CA) 14%) manufactured by Sankyo Oil Co., Ltd. as mineral oil, and Mitsui Chemicals, Inc. as synthetic wax The special monomer 1120H (140 degreeC viscosity 40mPa * s, weight average molecular weight 2100; synthetic wax which modified polyethylene wax) was used.

The physical property values of the asphalt modifier were evaluated by the following method.
The viscosity at 140 ° C. was measured in accordance with JIS K7117 “Method for measuring viscosity with a rotational viscometer”.
The weight average molecular weight (Mw) was measured by gel permeation chromatography (GPC).
The melt flow rate (190 ° C., 21.2 N) was measured at a test temperature of 190 ° C. and a load of 21.2 N in ASTM D1238 “Test Method for Flow Rates of Thermoplastics by Extension Plasometer”.
The softening point was measured according to JIS K2207 “Petroleum Asphalt—Softening Point Test Method”.

(Preparation of mixture test specimen and mixture test)
An asphalt mixture was produced using the above asphalt modifier, the aggregates shown in Table 2, and the following asphalts. The production method and the test of the obtained asphalt mixture are shown separately below.
Asphalt A Nippon Oil Corporation Negishi Refinery Straight Asphalt 60-80,
Asphalt B Modified Nippon Asphalt Ecophalt K2, made by Nippon Oil Corporation
Asphalt C High viscosity modified asphalt Ecophalt TA manufactured by Nippon Oil Corporation.

(Production of dense particle size asphalt mixture (13))
Aggregate the aggregates shown in Table 2 and asphalt A or asphalt B using a pug mill mixer, and add a predetermined amount of asphalt modifiers A to G (shown in Table 3) and stir and mix for 1 minute. Produced an asphalt mixture (dense particle size asphalt mixture (13)). This production simulates a so-called plant mix system in an actual asphalt mixture plant.

The obtained asphalt mixture was divided into six equal parts to prepare six test specimens for Marshall test, and the Marshall stability was evaluated.
The amount of asphalt was blended so that the total amount of asphalt and asphalt modifier was 5.7% by mass with respect to the aggregate. (The amount of asphalt modifier added to asphalt is shown in Table 3.) Aggregate heating temperature is 180 ° C, asphalt heating temperature is 170 ° C, stirring and mixing temperature during preparation of asphalt mixture is 175 ° C, specimen compaction The temperature was 160 ° C. and the number of compactions was 50 times on one side.

(Marshall test)
Japan Road Association "Pavement Test Method Handbook" 3-7-1 "Marshall Stability Test Method"
The side surface of the above-mentioned Marshall test specimen (cylindrical specimen (diameter: about 100 mm, thickness: about 63 mm)) is sandwiched between two arc-shaped loading heads and loaded at a specified temperature (60 ° C) and a specified loading speed. And the maximum load (stability kN) shown until the specimen breaks is measured.
The larger the maximum load (kN) value, the better the stability of the asphalt mixture.

(Wheel tracking test)
3-7-3 “Wheel Tracking Test Method” of the Japan Road Association “Pavement Test Method Handbook”
A specimen formed by placing an asphalt mixture in a predetermined mold (300 × 300 × 50 mm) was reciprocated with a small wheel with a specified load (686 ± 10 N) in a constant temperature room at 60 ° C., and the deformation amount at 45 minutes and 60 minutes ( The amount of rutting is measured, the dynamic stability (times / mm) is determined, and the resistance of the asphalt mixture to rutting is evaluated.
The larger the value of the dynamic stability (DS), the better the rutting resistance of the asphalt mixture at high temperature.

(Evaluation result of dense particle size asphalt mixture (13))
Table 3 shows the evaluation results of the Marshall test and the wheel tracking test of the dense particle size asphalt mixture (13).

Examples 1 to 4 are examples in which an asphalt mixture produced by modifying asphalt A and asphalt B with the asphalt modifiers A to C of the present invention was tested and evaluated. Since the asphalt modifiers A to C are excellent in melt dispersibility, the modifier can be uniformly dispersed during the production of the asphalt mixture, so the variation in the Marshall stability of the prepared Marshall specimen is small and the physical strength is low. A uniform specimen has been produced.
Furthermore, in the comparison between Examples 1, 2, 4 and Comparative Example 1, the addition of asphalt modifiers A to C shows an improvement in Marshall strength, that is, an improvement in the physical strength of the mixture. In addition, it is confirmed that the dynamic stability is improved by the wheel tracking test, that is, the rutting resistance is improved.
Also in the comparison between Example 3 and Comparative Example 2, the addition of asphalt modifier B also shows improvement in Marshall strength, that is, improvement in physical strength of the mixture. In addition, it is confirmed that the dynamic stability is improved by the wheel tracking test, that is, the rutting resistance is improved.
Since Comparative Example 3 has a high blending ratio of mineral oil in the used modifier, the viscosity of the modifier is less than 150 × 10 ³ mPa · s, and the softening point is less than 90 ° C., the prepared Marshall specimen The improvement of the marshall strength of the material, that is, the effect of improving the physical strength of the mixture and the effect of improving the dynamic stability by the wheel tracking test are not obtained so much, and it is not suitable as a pavement material.

Moreover, since the comparative example 4 has insufficient mineral oil in the asphalt modifier E, the compatibility of the high molecular weight polymer cannot be sufficiently increased, and cannot be quickly and uniformly mixed in the asphalt. Similarly, the variation in Marshall stability of Marshall specimens prepared in the same manner is very large, and is not suitable as a paving material.
Further, in Comparative Example 5, since the synthetic wax in the asphalt modifier F is excessive, the blending ratio of the high molecular polymer in the asphalt modifier is small, so the asphalt modification effect cannot be obtained. The stability value cannot be improved, and the variation in Marshall stability is large, making it unsuitable as a paving material.
In Comparative Example 6, since the synthetic wax is not included in the asphalt modifier G, the viscosity and softening point of the asphalt modifier is increased, and the handling property of the modifier is deteriorated, so the Marshall stability value is improved. In addition, the stability of the Marshall stability is large, making it unsuitable as a paving material.

(Evaluation using asphalt mixture for drainage pavement)
Aggregate the aggregates shown in Table 4 and asphalt B or asphalt C using a pug mill mixer, and add asphalt modifiers A to G (shown in Table 5) and stir and mix for 1 minute. Asphalt mixture (drainage pavement asphalt mixture) was manufactured. This production simulates a so-called plant mix system in an actual asphalt mixture plant.

The obtained asphalt mixture was divided into six equal parts, six test specimens for cantable tests were prepared, and the cantable loss rate at 20 ° C. was evaluated.
The amount of asphalt was blended so that the total amount of asphalt and asphalt modifier was 5.8% by mass with respect to the aggregate. The aggregate heating temperature was 180 ° C., the asphalt heating temperature was 170 ° C., the stirring and mixing temperature during preparation of the asphalt mixture was 175 ° C., the specimen compaction temperature was 160 ° C., and the number of compactions was 50 times on both sides.

(Cantablo test)
1-1-2T "Cantablo Test Method" of the Japan Road Association "Pavement Test Method Handbook" Using the above-mentioned test specimen for cantabro test using a Los Angeles tester (a machine prescribed in the coarse aggregate grinding test method) The drum is rotated 300 times at a rotation speed of 30 to 33 revolutions per minute, and the loss after the test is measured.
Loss rate (%) = (Sample weight before test (g) −Sample weight after test (g)) / Sample weight before test (g) × 100
The smaller the value of the loss rate (%), the better the stability of the drainage pavement asphalt mixture.

(Wheel tracking test)
The evaluation test of the asphalt mixture for drainage pavement was conducted in the same manner as the evaluation test of the dense particle size asphalt mixture (13).

(Evaluation results of asphalt mixture for drainage pavement)
Table 5 shows the evaluation results of the cantabulo test and the wheel tracking test of the asphalt mixture for drainage pavement.

Examples 5 to 8 are examples in which asphalt B and asphalt C were modified with the asphalt modifiers A to C of the present invention and were tested and evaluated. Since the asphalt modifiers A to C are excellent in melt dispersibility, they can be uniformly dispersed during the production of the asphalt mixture. Therefore, the specimens with a small variation in the cantabulo loss rate of the prepared cantabulo specimens and a uniform physical strength Is made.
Furthermore, in the comparison between Examples 5, 6, and 8 and Comparative Example 7, the addition of asphalt modifiers A to C confirms a decrease in cantabulo loss rate, that is, an improvement in aggregate scattering resistance. In addition, it is confirmed that the dynamic stability is improved by the wheel tracking test, that is, the rutting resistance is improved.
Also in the comparison between Example 7 and Comparative Example 8, the addition of the asphalt modifier B also confirms a decrease in cantabulo loss rate, that is, an improvement in aggregate scattering resistance. In addition, it is confirmed that the dynamic stability is improved by the wheel tracking test, that is, the rutting resistance is improved.
In Comparative Example 9, since the softening point of the petroleum resin used for the asphalt modifier is high and the molecular weight is large, the melt dispersibility in the asphalt and the compatibility with the high molecular weight polymer are reduced. The asphalt modifier cannot be evenly dispersed at times, and the variation in the cantal loss rate of the prepared Marshall specimen is very large, which is an unsuitable example for a paving material.

In addition, since Comparative Example 9 has a high blending ratio of mineral oil in the used modifier, the viscosity of the modifier is less than 150 × 10 ³ mPa · s, and the softening point is less than 90 ° C., so the wheel tracking test The improvement effect of the dynamic stability by is not obtained so much and it is not suitable as a pavement material.
Furthermore, since Comparative Example 10 lacks the mineral oil in the asphalt modifier E, the compatibility of the polymer cannot be sufficiently increased, and cannot be mixed quickly and uniformly in the asphalt. The prepared cantabro test specimens have a very large variation in the cantabulo loss rate, making them unsuitable as paving materials.
In Comparative Example 11, since the synthetic wax in the asphalt modifier F is excessive, the blending ratio of the high molecular polymer in the asphalt modifier is small, so that the modification effect of asphalt cannot be obtained. The variation of the cantabulo loss rate of the test specimen is very large, and the effect of improving the dynamic stability by the wheel tracking test is not seen, which makes it unsuitable as a paving material.
Since Comparative Example 12 does not contain synthetic wax in the asphalt modifier G, the viscosity and softening point of the asphalt modifier is increased, and the handling property of the modifier is deteriorated. In addition, the variation of the cantabulous loss rate is large, making it unsuitable as a paving material.

Claims (3)

Mineral oil having a condensed polycyclic aromatic (PCA) content of less than 3% by mass, a kinematic viscosity at 60 ° C. of ²⁰ to 200 mm ² / s, and an aromatic content (% CA) of 5 to 25% with respect to 100 parts by weight of the polymer. Viscosity at 150 ° C. obtained by heating and mixing 50 to 100 parts by weight, 10 to 70 mPa · s at 140 ° C. and 10 to 50 parts by weight of synthetic wax having a weight average molecular weight of 1 × 10 ^{3 to} 3 × 10 ³ × 10 ^{3 to} 350 × 10 ³ mPa · s, weight average molecular weight (Mw) is 10 × 10 ^{3 to} 100 × 10 ³ , melt flow rate (190 ° C., 21.2 N) is 20 to 150 g / 10 min, softening point Is an asphalt modifier characterized by having a temperature of 90 to 130 ° C.   In an asphalt mixture plant, 3 to 40 parts by weight of the asphalt modifier according to claim 1 is added to 100 parts by weight of asphalt and asphalt in an amount of 4 to 10% by mass with respect to the aggregate and aggregate. Asphalt mixture obtained by heating and mixing.   In an asphalt mixture plant, 3 to 40 parts by weight of the asphalt modifier according to claim 1 with respect to 100 parts by weight of asphalt and asphalt in an amount of 4 to 10% by mass with respect to the aggregate and aggregate. A method for producing an asphalt mixture comprising heating and mixing.