JP5615690B2 - Polymer modified asphalt composition - Google Patents

Description

  The present invention relates to a polymer-modified asphalt composition that is suitable for a highly durable drainage pavement and has a low viscosity and a high strength.

  Conventionally, asphalt has been used in a wide range of fields such as road paving and waterproofing. One application of asphalt compositions is drainage pavement that can effectively drain rainwater from the pavement surface. Many drainage pavements are constructed on expressways and ordinary roads, and greatly contribute to ensuring safety during driving and noise countermeasures.

  In drainage pavement, it is necessary to have a gap between the aggregates to pass rainwater from the pavement surface to the base layer. For this reason, even if the contact point between aggregates decreases, it is necessary to use the binder with the big grasp power of the aggregate which adhere | attaches aggregates firmly.

  From this point of view, a polymer modified asphalt to which a modifier such as a thermoplastic elastomer is added at about 10% by weight has been developed, and the Japan Modified Asphalt Association has established a quality standard as a polymer modified asphalt H type.

  However, in drainage pavement using polymer-modified asphalt H type, voids are crushed, drowned, and aggregates scattered in high-load areas such as expressways, intersection inflows, and places with heavy traffic on large vehicles. The pavement is damaged. Due to the damage of the pavement, the expected drainage performance in drainage pavement cannot be demonstrated, water repellent to oncoming vehicles and pedestrians in rainy weather, steering wheel trapping during running, anti-slip effect There are problems that cannot be ignored for road safety, such as reduction and worsening of driving.

  In order to solve these problems, the mechanical strength such as the complex elastic modulus is increased by increasing the blending amount of the thermoplastic elastomer than the polymer-modified asphalt H type while maintaining the drainage function described above. Water-soluble pavement polymer modified asphalt has been developed and commercialized.

  However, the asphalt melt viscosity increases in proportion to the blended amount of the thermoplastic elastomer. For this reason, the polymer modified asphalt for drainage pavement with high durability has remarkably poor work efficiency during production and paving under the same temperature conditions as the polymer modified asphalt H type.

  Therefore, highly durable polymer modified asphalt for drainage pavement is melted by operating at a temperature condition higher by 10 ° C than the temperature condition at the time of manufacturing and paving the polymer modified asphalt type H, especially in winter. The viscosity was lowered to ensure workability.

  However, especially in the winter, the temperature often drops more than expected due to the influence of the outside air temperature while transporting the mixture produced at the mixture plant to the pavement site. In such a case, since the viscosity increases, the workability is remarkably deteriorated and the handling at the construction site becomes difficult.

  In order to solve such problems, a technique is often employed in which the mixing temperature is further increased to prevent deterioration of workability due to cooling during transportation. However, when such a method is adopted, the melt viscosity of the asphalt is too low, and the asphalt is often dropped from the aggregate, resulting in a problem that the amount of the asphalt is less than the designed amount. In such a case, the performance as a paving body is remarkably lowered, and there is a problem that high durability cannot be expressed.

  That is, a highly durable polymer modified asphalt for drainage pavement has a problem that it is very difficult to control the temperature during production and paving.

  In order to solve the above-described problems caused by workability during manufacturing and paving due to high melt viscosity, the following techniques have been proposed in recent years.

  First, Patent Documents 1 and 2 disclose a technique that utilizes a bearing effect by adding a foam-based material and generating fine bubbles in asphalt.

  Patent Document 3 discloses a technology for adding water or steam to asphalt to generate bubbles and lowering the viscosity.

  Furthermore, Patent Documents 4 and 5 disclose a technique using an additive (medium temperature increasing material) that reduces the viscosity of asphalt.

  However, in order to secure foaming time, the disclosed techniques of Patent Documents 1 to 3 are added every 1 batch at the time of manufacturing the asphalt mixture (1 to 4 tons / batch for most heated asphalt mixture manufacturing factories). It is necessary to add an agent or a substance containing moisture. For this reason, in this disclosed technology, quality variations are likely to occur between mixtures having different production times. Furthermore, since an additive or a substance containing moisture must be manually input, if the asphalt mixture used in the construction is large, a large amount of labor is required and the production capacity of the asphalt mixture is reduced. Become.

  In addition, petroleum-based waxes and synthetic-based waxes have been studied as additives used as a viscosity reducing agent for asphalt in the disclosed technologies of Patent Documents 4 and 5, but these may cause a decrease in performance of paving materials. Therefore, there is a problem that it is necessary to add a reinforcing material separately. Further, the compatibility of the thermoplastic elastomer in the asphalt tends to be deteriorated and the storage stability tends to be lowered, and there is a problem that an additional compatibilizing agent is required.

JP 2001-131321 A JP 2002-332606 A JP 2001-64065 A JP 2006-57077 A Special table 2002-538231 gazette

  Therefore, the present invention has been devised in view of the above-mentioned problems, and the object of the present invention is to achieve high durability while maintaining work efficiency in manufacturing / paving equivalent to or higher than that of polymer-modified asphalt H type. Another object of the present invention is to provide a polymer-modified asphalt composition capable of expressing the performance desired as a water-based drainage pavement and a method for producing the same.

  In order to solve the above-mentioned problems, the present inventors have optimized the styrenic thermoplastic elastomer itself added as an essential component to the polymer-modified asphalt, thereby obtaining the performance required as a highly durable drainage pavement. Moreover, paying attention to the fact that the melt viscosity of the binder is lowered, intensive studies were conducted.

  As a result, in the styrene-based thermoplastic elastomer, it was found that the properties of styrene content and 25% toluene solution viscosity affect the melt viscosity of the polymer-modified asphalt and the strength as a pavement. The inventors have invented a polymer-modified asphalt composition that can be solved.

The polymer-modified asphalt composition according to claim 1, comprising a base asphalt, an SBS having a styrene content in the range of 35 to 70% by weight and a 25% toluene solution viscosity in the range of 150 to 1500 mPa · s and A styrene-based thermoplastic elastomer containing at least one selected from SBBS: 13 to 19% by weight only .

The polymer-modified asphalt composition according to claim 2, comprising base asphalt, SBS having a styrene content in the range of 35 to 70% by weight, and a 25% toluene solution viscosity in the range of 150 to 1500 mPa · s and It contains only styrene thermoplastic elastomer containing 13 to 19% by weight and at least one anti-peeling agent of 0.3 to 1.0% by weight containing at least one selected from SBBS.

  With the polymer-modified asphalt according to the present invention having the above-described configuration, performance required for highly durable drainage pavement, that is, flow resistance (DS value), aggregate scattering at low temperature (low temperature cantabulo loss amount), water resistance Properties (residual stability) and sag (sag test), and low viscosity physical properties equal to or lower than those of the polymer-modified asphalt H type. For this reason, in the present invention, it becomes possible to manufacture and pave under the temperature conditions equal to or lower than the temperature conditions during the production and pavement of the conventional polymer-modified asphalt H type, and it becomes possible to improve workability and handleability.

It is a perspective view which shows typically the measurement part of a dynamic viscoelasticity testing machine.

  Hereinafter, the polymer-modified asphalt composition will be described in detail as a mode for carrying out the present invention.

  Hereinafter, the polymer-modified asphalt composition to which the present invention is applied is a base asphalt, SBS having a styrene content in the range of 35 to 70% by weight and a 25% toluene solution viscosity in the range of 150 to 1500 mPa · s. , Styrenic thermoplastic elastomer containing at least one SBBS: 13 to 19% by weight. At this time, the anti-peeling agent may be contained in an amount of 0.3 to 1.0% by weight.

  Hereinafter, the details of each component of the polymer-modified asphalt composition to which the present invention is applied and the reasons for limiting the numerical values will be described.

Base asphalt

  As the asphalt in the present invention, for example, straight asphalt (see JIS K 2207), blown asphalt (see JIS K 2207), semi-blown asphalt ("asphalt pavement outline", published by the Japan Road Association, January 13, 1997 Japan, p. 51, see Table-3.3.4), solvent deasphalting asphalt (see “New Petroleum Dictionary”, edited by Petroleum Institute of Japan, 1982, p. 308), etc. In addition, various types of asphalt to which an aromatic heavy mineral oil or the like is added can be used.

  In the present invention, asphalt penetration grades are examined, and straight asphalt 60/80 to 100/120 equivalent products can be used.

  In general, the lower the penetration grade, the higher the mechanical strength typified by DS value, but the lower the low-temperature properties typified by bending work and bending stiffness.

  In the present invention, the base asphalt used is preferably an asphalt obtained by adding an aromatic heavy mineral oil to a solvent deasphalted asphalt.

  As the solvent deasphalted asphalt, propane or propane deasphalted asphalt using propane and butane is preferable.

  Examples of aromatic heavy mineral oil include petroleum solvent extraction oil, aromatic hydrocarbon process oil containing at least 35% by mass of aromatic hydrocarbons as defined in JISK6200, and vacuum distillation residue of crude oil. Solvent extracted oil obtained by defoaming with propane or the like is further extracted with a polar solvent such as furfural to obtain bright stock (heavy lubricating oil). There is.

  In the present invention, it is preferable to add an extract as the aromatic heavy mineral oil.

  The role of the extract in the present invention is to increase the solubility of the thermoplastic elastomer in asphalt and prevent separation in storage stability. If the amount of the thermoplastic elastomer added is large, the required amount of the extract is also increased. To increase. Moreover, when the extract more than needed is added with respect to the addition amount of a thermoplastic elastomer, intensity | strength will fall.

  The content of the base asphalt with respect to the entire asphalt composition is desirably 87 to 80% by weight.

  The content of the extract relative to the entire asphalt composition is the penetration, softening point, storage stability, complex elastic modulus indicating strength, dynamic stability (DS value) in the wheel tracking test, and low temperature indicating low temperature properties. Although it is determined in consideration of the amount of cantabulo loss, the content of the extract with respect to the entire asphalt composition is preferably 20 to 27% by weight within the range examined in the present invention.

Styrenic thermoplastic elastomer

  The styrenic thermoplastic elastomer used in the polymer-modified asphalt composition of the present invention includes a styrene-butadiene-styrene block copolymer (SBS) and a styrene-butadiene selectively hydrogenated with a vinyl group of a butadiene block in SBS. -Among the butylene-styrene block copolymers (SBBS), at least one of those specified below is included in the formulation.

  Here, SBBS has excellent heat resistance and weather resistance such as heat, light, and mechanical shear during production, processing, and use by selectively hydrogenating the vinyl group of the butadiene block in SBS. It has something. The polybutadiene block in SBS has 1,4-cis bonds, 1,4-trans bonds, and 1,2-bonds, and the unsaturated double bonds remaining in each of them are easily damaged by heat and ultraviolet rays. Therefore, a styrene-ethylene-butylene-styrene block copolymer (SEBS), which is obtained by hydrogenating an unsaturated double bond of SBS and imparting heat resistance and weather resistance, can be formulated to solve the above problems. It was. However, due to the change in molecular chain flexibility due to hydrogenation, SEBS has lower performance in the low temperature range than SBS, and when used as a polymer-modified asphalt, cracks and rock jumps in cold snowy areas. There was a problem that caused such as.

  In view of this problem, SBBS has been improved. This is one of 1,4-cis bond, 1,4-trans bond, and 1,2 bond, which is the most reactive and selectively hydrogenated to 1,2 bond which is likely to cause gelation. It is. Thereby, by leaving the double bond in the main chain, the heat resistance and weather resistance can be greatly improved while maintaining the flexibility of the molecular chain.

  Therefore, SBBS has substantially the same low-temperature performance, workability, and modification effect due to its addition as SBS. That is, SBBS is a thermoplastic elastomer having improved heat resistance and weather resistance, and other physical properties that are almost the same as SBS.

  SBS and SBBS must have a styrene content in the range of 35 to 70% by weight and a 25% toluene solution viscosity in the range of 150 to 1500 mPa · s. Preferably, the styrene content is 35 to 55. The styrene content is 39 to 46% by weight and the 25% toluene solution viscosity is 150 to 700 mPa · s.

  The SBS and SBBS are characterized by increasing the styrene content. Compared to SBS and SBBS with a styrene content of about 30% by weight, the proportion of polybutadiene blocks with a large amount of linear components is lowered by increasing the styrene content, and the molecular length of the entire polymer is shortened. Thus, the thickening effect given to the asphalt composition is lower than that of the conventional one. Further, by increasing the content ratio of the polystyrene block to which bulky aromatic groups are bonded, it becomes possible to improve the rigidity of SBS and SBBS itself, and the complex elastic modulus and DS value of the modified asphalt composition itself. As a result, mechanical properties such as strength can be improved.

  Here, when the styrene content in SBS and SBBS is less than 35% by weight, the proportion of the butadiene block increases and the viscosity increases. Therefore, when it is used for blending polymer modified asphalt for highly durable drainage pavement, workability deteriorates at the same temperature as general drainage at the time of production and paving.

  On the other hand, if the styrene content exceeds 70% by weight, styrene has a higher glass transition temperature than straight-chain components such as butadiene, and tends to break in a low temperature range, thus lowering the low-temperature properties. In addition, since the effect of flexibility caused by a linear component such as butadiene is reduced, the elastic force of the asphalt composition is lost, which causes deterioration of mechanical properties.

  For this reason, the styrene content in SBS and SBBS needs to be 35-70 weight%.

  In addition, by setting the upper limit of the styrene content in SBS and SBBS to 55% by weight, the above-described reduction in low-temperature properties can be further prevented, and the effect of flexibility provided by the linear component can be further improved. It becomes possible to improve the elastic force of the asphalt composition and thus to prevent the deterioration of mechanical properties more reliably.

  Furthermore, by setting the styrene content in SBS and SBBS to 39 to 46% by weight, it becomes possible to realize both the suppression of increase in viscosity and the improvement of the mechanical properties of the asphalt composition in a more effective and balanced manner. .

  Further, when the viscosity of the 25% toluene solution in SBS and SBBS is smaller than 150 mPa · s, it is not preferable because the molecular weight becomes too low to obtain a sufficient modification effect.

  On the other hand, when the viscosity of a 25% toluene solution in SBS and SBBS is greater than 1500 mPa · s, the molecular weight becomes too high, resulting in a marked increase in the viscosity of the resulting asphalt composition, making manufacturing and paving difficult. It is not preferable.

  In addition, by setting the upper limit of the viscosity of the 25% toluene solution in SBS and SBBS to 1000 mPa · s, it is possible to make the handling easier by effectively suppressing an increase in viscosity due to an increase in molecular weight. It becomes possible. Further, by setting the upper limit of the viscosity of the 25% toluene solution in SBS to 700 mPa · s, it is possible to further enhance the effect and obtain a more suitable property.

  The amount of SBS and SBBS described above is 13 to 19% by weight, preferably 13 to 18% by weight, more preferably 15 to 18% by weight, based on the entire asphalt composition. The addition amount here means the addition amount of each SBS or SBBS when only the above-mentioned SBS or SBBS is added, but when SBS and SBBS are mixed, it means the total addition amount. To do.

  Here, when the blending amount of SBS and SBBS is less than 13% by weight, the mechanical effect and the like as a highly durable drainage pavement polymer modified asphalt cannot be obtained. On the other hand, when the blending amount exceeds 19% by weight, the reforming effect is high and the mechanical properties are excellent, but the thickening effect is high and the intended workability cannot be obtained.

  Further, by setting the upper limit of the addition amount of SBS and SBBS to 18% by weight or less with respect to the entire asphalt composition, the thickening effect can be further reduced. For example, the viscosity at 180 ° C. is set to 700 mPa · s. It becomes possible to reduce to a grade, and it becomes possible to improve workability and ease of handling.

  Furthermore, by setting the lower limit of the addition amount of SBS and SBBS to 15% by weight or more with respect to the entire asphalt composition, the mechanical properties of the obtained asphalt composition can be further improved.

  In addition, in this invention, it is not limited to adding SBS or SBBS which exists in the range of the physical property mentioned above, You may make it add both SBS and SBBS. It is only necessary that 13 to 19% by weight of the thermoplastic elastomer mixed with SBS and SBBS is added. That is, it is only necessary to contain 13 to 19% by weight of a styrenic thermoplastic elastomer containing at least one selected from SBS and SBBS within the above-described physical property range.

Anti-peeling agent

  In the present invention, it is preferable to add an anti-peeling agent in order to prevent exfoliation of the asphalt composition and the aggregate.

  Resin acid can be preferably used as the anti-peeling agent, but the resin acid is a C20 polycyclic diterpene having a carboxyl group, and is abietic acid, dehydroabietic acid, neoabietic acid, pimaric acid, isopimaric acid, It is a rosin containing any one or more of parastrinic acid.

  As the rosin, gum rosin, wood rosin, tall oil rosin and the like are used. These rosins can be classified as gum rosin, wood rosin, etc. as described above depending on the origin, raw materials, and collection method, but are obtained as a residual component at the time of steam distillation of pine resin. This rosin is a mixture containing, as components, abietic acid, parastrinic acid, neoabietic acid, dehydroabietic acid, pimaric acid, sandaracopimaric acid, isopimaric acid and the like. This rosin usually softens at about 80 ° C. and melts at 90-100 ° C. Note that rosin contains various resin acids such as abietic acid, dehydroabietic acid, dihydroabietic acid, tetrahydroabietic acid, parastrinic acid, neoabietic acid, and levopimaric acid. It may be used alone.

  In the present invention, gum rosin is used as a preferred rosin, but is not limited thereby.

  In addition, many resin acids often have an effect of improving compatibility.

  If the content of the resin acid is less than 0.3% by weight, the effect of the resin acid is not sufficient, and it is impossible to prevent peeling and improve compatibility as a final product. On the other hand, when the content of the resin acid exceeds 1% by weight, not only the effect of preventing peeling and improving the compatibility is saturated, but also the amount of expensive resin acid added is increased. This raises the problem that the cost of raw materials is significantly increased. That is, even if the resin acid content exceeds 1% by weight, the prevention of peeling and the improvement of the compatibility are not significantly improved, but it is disadvantageous in terms of raw material costs. For this reason, it is desirable that the content of the resin acid is 0.3 to 1.0% by weight.

  The present invention will be specifically described below with reference to test methods, examples and comparative examples used in the present invention, but the present invention is not limited to these examples. In addition, in the following examples, when only% is described, it indicates weight%.

  In the present invention, as shown in Table 1, for samples obtained for experimental investigation, penetration (25 ° C.), softening point, viscosity (180 ° C.), complex modulus (60 ° C.), separation test A property test consisting of the items (170 ° C., 72 hours) is performed. Moreover, the mixture which consists of the item of a wheel tracking test (60 degreeC), a low-temperature cantabulo test (-20 degreeC), a Marshall stability test (60 degreeC), a water immersion marshall stability test (60 degreeC), and a droop test (170 degreeC). Perform a performance test. Hereinafter, a detailed test method will be described.

  The penetration (25 ° C.) was measured by JIS K 2207 “Petroleum Asphalt—Penetration Test Method”. This value is preferably 40 (0.1 mm) or more.

  The softening point was measured by JIS K 2207 “Petroleum Asphalt—Softening Point Test Method”. This value is preferably 80.0 (° C.) or higher.

  Viscosity (180 ° C.) was measured under the conditions of JPI-5S-54-99 “Viscosity Test Method Using Asphalt-Rotational Viscometer” at a measuring temperature of 180 ° C., a spindle SC4-21, a spindle rotation speed of 20 revolutions / minute. did. When the viscosity exceeds 2000 mPa · s, it becomes difficult to produce a mixture by mixing with the aggregate at that temperature. Accordingly, the viscosity (180 ° C.) is preferably 2000 mPa · s or less.

The complex elastic modulus (G ^* ) was measured in accordance with a dynamic shear rheometer (DSR) test method defined in the Pavement Survey and Test Method Handbook (edited by the Japan Road Association). As shown in FIG. 1, the measurement principle of this test is as follows. An asphalt composition as a measurement sample is sandwiched between two parallel disks 2a and 2b (diameter is 25 mm), and one disk 2a has a sine wave having a predetermined frequency. Strain is applied to the sine stress σ transmitted to the other disk 2b through the asphalt composition 1 (thickness 1 mm), and the complex elastic modulus is obtained from the sine stress and sine wave strain.

The measurement conditions used in the present invention were a measurement temperature of 60 ° C. for evaluating durability during service (summer), and a measurement frequency of 0.1 rad / sec for evaluation at a low shear rate at which asphalt flow tends to occur. The strain was 10%. Based on the measurement result, the complex elastic modulus (G ^* ) was determined from the following mathematical formula (1). Here, γ in the following formula (1) is the maximum strain applied to the disk.

The complex elastic modulus (G ^* ) is known to correlate with the DS value in the frequency range of 0.1 rad / sec, and the performance as a paving body can be known to some extent without preparing a mixture.

The complex elastic modulus (G ^* ) targeted in the present invention is 2000 Pa or more, preferably 2500 Pa or more. The asphalt composition exhibiting such a complex elastic modulus (G ^* ) has a DS value of 6000 described later. There is a high possibility of obtaining a high value of times / mm, and further 7000 times / mm. However, this value is a guideline, and in order to clarify the performance as a paving body, it is necessary to actually prepare a mixture.

  In the separation test (170 ° C.), the asphalt composition (about 250 g) of the present invention was poured into an aluminum cylindrical can having an inner diameter of 5.2 cm and a height of 13 cm to a depth of 12 cm, and sealed at 170 ° C. Heated for 72 hours. Thereafter, the softening points at the top 4 cm and the bottom 4 cm of the asphalt composition injected into the aluminum cylindrical can were measured based on JISK2207. It is preferable that the absolute value of the difference value between the upper softening point and the lower softening point is taken, that is, the absolute value of the difference between the softening points is 3 or less. Therefore, in Table 1, when the absolute value of the difference between the softening points is 3 or less, the result is ◯, and when it exceeds 3, the result is ×.

  The DS value (dynamic stability) was 30 cm in length, 30 cm in width, thickness, which was prepared by using each modified asphalt composition and the aggregates shown in Table 2 and making the amount of asphalt in the mixture 5.0% by weight. A 5 cm long sheet-like specimen was used and measured according to the wheel tracking test method defined in the Pavement Survey and Test Method Handbook (edited by the Japan Road Association). Japanese roads have been experimentally confirmed to reach a temperature of about 60 ° C in summer. In this state, when a car passes over the vehicle, it is deformed by flow and digging or the like occurs. The wheel tracking test is a test designed to experimentally confirm the degree of occurrence of this digging, and is a test conducted to evaluate the dynamic stability, which is an index of flow resistance in pavement materials. It is. Specifically, in a constant temperature bath maintained at 60 ° C., a tire loaded with a predetermined load was reciprocated for 1 hour on a specimen (specimen), and the amount of deformation was measured.

  The DS value (times / mm) is as follows using the deformation amount (mm) for 15 minutes from 45 minutes to 60 minutes after the start of the test and the number of times of running the tire (times) for 15 minutes from 45 minutes to 60 minutes after the start of the test. It calculates | requires using Numerical formula (2) of these.

  DS value (times / mm) = (number of times the tire travels between 45 minutes and 60 minutes (times)) / (deformation amount between 45 minutes and 60 minutes (mm)) ... (2)

  The higher the DS value, the higher the strength of the asphalt, which means that a paving material that is strong against digging can be provided. When the DS value is 6000 times / mm or more in the above-mentioned pavement survey / test method manual, the DS value is to be reported as 6000 times / mm or more. Therefore, the actually obtained DS value was used. Further, in consideration of the result of the above-described complex elastic modulus, a desirable DS value is set to 6000 times / mm or more, preferably 7000 times / mm or more.

  For Marshall stability, each modified asphalt composition and aggregates shown in Table 2 were used, and a test piece prepared with 5.0% by weight of asphalt in the mixture was used. Was measured according to the Marshall stability test method described in 1. Similarly, water immersion marshall stability was also measured. In this method, the Marshall stability test is performed after the specimen is immersed in 60 ° C. warm water for 48 hours. Note that the residual stability (%) can be calculated from the Marshall stability and the water-immersed Marshall stability using Equation (3).

  Residual stability (%) = Water-immersed Marshall stability (kN)) / Marshall stability (kN)) (3)

  This Marshall stability is a test conducted to determine the blending ratio of coarse / fine aggregate and asphalt, and the higher this value, the less likely it is to flow at a high temperature or wave-like deformation. The desirable Marshall stability for the present invention is 4.5 kN or more.

  Further, the water immersion marshall stability is a test for evaluating water resistance, and the desired residual stability in the present invention is 75% or more, more preferably 80% or more.

  The amount of low-temperature cantabulo loss is determined by a cantabulo test described below. This cantabulo test is a test for evaluating the aggregate scattering resistance of a porous asphalt mixture, and was performed according to the method described in the pavement survey and test method manual. Put the specimen for the Marshall stability test into a -20 ° C Los Angeles testing machine (a machine specified in the coarse aggregate abrasion test method), rotate the drum 300 times without using steel balls, and calculate the loss after the test. It was measured. The loss amount was calculated from Equation (4).

  Loss amount (%) = {Specimen mass before test (g) −Specimen mass after test (g)} / Specimen mass before test (g) × 100 (4) )

  The low-temperature cantabulo loss amount evaluates the aggregate scattering resistance of a pavement such as a snowy cold region. In the present invention, it is desirably 20% or less, more preferably 15% or less.

  The amount of sag is used to determine the surplus asphalt mortar content when a certain amount of asphalt is added to an asphalt mixture of a predetermined particle size. In general, the optimum asphalt amount is set at the same temperature as the mixing temperature when designing the drainage pavement. In this examination, it was performed in accordance with the method described in the pavement survey / test method manual, the temperature condition was set to 170 ° C., and the sagging amount was calculated from Equation (5). In addition, a saucer here is a thing of about 42 cm x about 27 cm of the grade which spreads asphalt mixture more uniformly.

  Sagging amount (%) = [Mortar mass adhering to saucer (g) −mass of saucer (g)] / [Amount of mixed material before saucer and test (g) −mass of saucer (g)] × 100 (5)

  The sag test is used for the purpose of determining the maximum amount of asphalt that the drainage pavement asphalt can hold statically at the mixing temperature. In the present invention, it is preferably 0.5% or less, more preferably 0.35% or less.

(About Examples 1-12 and Comparative Examples 1-7)

  Hereinafter, in order to verify the effect of the modified asphalt composition to which the present invention is applied, examples and comparative examples using SBS and SBBS as styrenic thermoplastic elastomers as modifiers will be described in detail.

  Samples composed of propane deasphalted asphalt, extract, styrene-based thermoplastic elastomer, and anti-peeling agent (gum rosin) having the blending ratios shown in Examples 1 to 12 and Comparative Examples 1 to 7 in Table 1 were prepared.

The properties of the propane deasphalting asphalt used in this verification are typical properties having a penetration of 8 (1/10 mm), a softening point of 66.5 ° C., and a density at 15 ° C. of 1028 kg / m ^3. is there.

Also, extract used has a density kinematic viscosity kinematic viscosity at 61.2mm ² / s, 40 ℃ in a typical property is 100 ° C. is at 3970mm ² / s, 15 ℃ is at 976.4kg / m ³ belongs to.

  Table 1 shows the SBS used in this verification. There are seven types of SBS having different styrene contents and 25% toluene solution viscosity. Of the seven types of SBS in total shown in Table 1, the top two stages are SBSs that are used as commercial products. On the other hand, the SBS from the third stage to the lowest stage is in the range of the physical properties that have been found for a new study to be applied to the modified asphalt composition according to the present invention.

  Table 1 also shows the SBBS used in this verification. As the SBBS, one type as shown in Table 1 is used for the styrene content and the viscosity of the 25% toluene solution. Such SBBS is also in the range of physical properties found for a new study to be applied to the modified asphalt composition according to the present invention.

  Incidentally, the method for measuring the styrene content is as follows: content of vinyl aromatic polymer block (A) (% by weight) = (weight of vinyl aromatic polymer block (A) in base non-hydrogenated copolymer / base Determined from the weight of the non-hydrogenated copolymer) × 100.

  In the case where the content of the polymer block (A) with respect to the hydrogenated conjugated diene copolymer is directly measured, the hydrogenated copolymer is used as a specimen by using a nuclear magnetic resonance apparatus (NMR) (Y Tanaka, et al., RUBBER CHEMISTRY and TECHNOLOGY 54, 685 (1981)).

  Moreover, the measuring method of a 25% toluene solution viscosity can be measured with a Brookfield (BL) type viscometer as described, for example in Unexamined-Japanese-Patent No. 2008-31267.

  The used anti-peeling agent was used for exhibiting anti-peeling properties and compatibility with the aggregate, and had an acid value of 156 (mg KOH / g: JIS K0070), a softening point of 77.0 ° C. ( JIS K2207) disproportionated gum rosin. This gum rosin is a rosin obtained by filtering the collected raw pine resin to remove impurities and then distilling it to separate the low-boiling component turpentine oil. This gum rosin generally has 20 to 40% by weight of abietic acid, 15 to 25% by weight of neoabietic acid, 20 to 30% by weight of parastrinic acid, 3 to 8% by weight of pimaric acid, and 10 to 10% of isopimaric acid. 20% by weight and 3-8% by weight of dehydroabietic acid. In this example, when this gum rosin is added, the content with respect to the entire composition is 0.5% by weight.

  A method for producing the polymer-modified asphalt composition for evaluation of the present invention having the above-described configuration will be described below.

  In a state where the propane deasphalted asphalt is melted at a temperature of about 150 ° C., the extract is mixed so that the blending ratio is as described above, and the modifier composed of the styrene-based thermoplastic elastomer described above is added in the same procedure, Furthermore, the above-mentioned gum rosin is added. The mixture was stirred and stirred for about 3 to 5 hours using a homomixer at the time of mixing at a temperature of 170 to 215 ° C. and a rotational speed of 1500 to 5000 rpm.

Table 1 shows the physical properties measured for each of the produced polymer-modified asphalt compositions. The physical property measurement items are roughly classified into a property test and a mixture performance test. In the property test, penetration (0.1 mm), softening point (° C.), viscosity at 180 ° C. (mPa · s), complex elastic modulus G ^* , 170 ° C. × 72 hour separation test (softening point at 25 ° C. If the absolute value of the difference is 3 or less, the test is performed for each item of ○) if the difference absolute value is 3 or more. In the performance test of the mixture, DS value at 60 ° C. (times / mm), Marshall stability (kN), water-immersed Marshall stability (kN), low temperature cantabulo loss at −20 ° C. (%), sagging at 170 ° C. The amount (%) is tested and the residual stability (%) is calculated.

  In these physical property values to be measured, preferred ranges in the present invention are as shown below.

  The penetration (25 ° C.) and softening point are 40 or more in penetration (25 ° C.) and 80 or more in softening point. This is the quality standard value of polymer modified asphalt for drainage pavement established by the Japan Modified Asphalt Association.

  If the viscosity (180 ° C.) exceeds 2000 mPa · s, the viscosity is too high and it is difficult to perform the construction at that temperature.

  The target value of the asphalt stiffness in the high temperature range is set to 2000 Pa or more, preferably 2500 Pa or more, using the complex elastic modulus (G *) measured by DSR (60 ° C.) as an index. If it is less than this value, the rigidity is low and the desired pavement strength cannot be maintained.

  Stability during heat storage was measured by a separation test (170 ° C.). The absolute value of the difference value between the upper softening point and the lower softening point was taken, and when the difference absolute value was 3 or less, it was marked with ◯.

  As an index of the difficulty of rutting in summer, the DS value obtained from the wheel tracking test result was 6000 times / mm or more, more preferably 7000 times / mm or more. If it falls below this, it suggests that rubbing is easy.

  As an index of aggregate scattering resistance in a low temperature range, the loss rate by a low temperature cantabulo test at −20 ° C. is preferably 20.0% or less, more preferably 15.0% or less. If it falls below this, it is suggested that aggregates are more likely to scatter in the lower temperature range than the current product.

  Marshall stability is 4.5 kN or more. The residual stability is 75% or more, more preferably 80% or more.

  The sagging amount at 170 ° C. is desirably 0.5% or less, and more preferably 0.35 or less. When exceeding this, the asphalt composition drips from the aggregate during transportation during production, and the paved body with the designed amount of asphalt cannot be paved.

  In Examples 1 to 12, both the styrene content with respect to the total weight of the styrenic thermoplastic elastomer and the viscosity of the 25% toluene solution, and the content ratio of the styrenic thermoplastic elastomer with respect to the entire modified asphalt were specified in the present invention. The formulation is within the range.

  Thereby, as for all Examples 1-12, 180 degreeC viscosity is 2000 mPa * s or less, the amount of sagging loss at 170 degreeC is 0.35 weight% or less, and also maintains the intensity | strength required as road pavement simultaneously. From the viewpoint, the complex elastic modulus G * is 2000 Pa or more.

  In contrast, Comparative Example 1 is a property of a polymer-modified asphalt H type that is currently commercially available. Similarly, Comparative Example 2 is a property of a polymer-modified asphalt HF type that is currently commercially available. In Comparative Examples 3 to 7, any one or more of the styrene content with respect to the total weight of the styrenic thermoplastic elastomer and the 25% toluene solution viscosity, and further the content of the styrenic thermoplastic elastomer with respect to the entire modified asphalt, It deviates from the scope defined in the present invention.

  In Comparative Examples 3 to 4, the styrene content of the SBS to be used and the viscosity of the 25% toluene solution deviate from the range defined in the present invention, and the content was within the range defined in the present invention. It is shown that the performance cannot be expressed, especially the viscosity increases, and the expected effect cannot be expressed.

  As shown in Comparative Example 3, when SBS having a styrene content of 31% and a 25% toluene solution viscosity of 4000 mPa · s was blended, the complex elastic modulus was greatly improved, but the viscosity was very high. It is shown that storage stability is also reduced.

  Comparative Example 4 uses a low molecular weight SBS having a styrene content of 30% and a toluene solution viscosity of 1700 mPa · s, compared with general SBS. The polymer-modified asphalt H shown in Comparative Examples 1 and 2 is used. The 180 ° C. viscosity is still high compared to the mold and HF type commercial product.

  On the other hand, in Examples 1 to 4, SBS having a styrene content and a toluene solution viscosity in the range defined in claim 1 was used. As a result, as shown in the example in the case of adding 15% by weight of SBS, it was possible to satisfy the performance target required as a polymer modified asphalt for a highly durable drainage pavement with a viscosity equal to or lower than that of a commercially available product. .

  However, when SBS having a styrene content deviating from the range specified in the present invention shown in Comparative Example 5 was added, the viscosity and the complex elastic modulus satisfied the target values, but the penetration was deteriorated to form a mixture. The properties at the time deteriorated remarkably. As a result, it is considered that as a result of excessively increasing the styrene content, flexibility was remarkably lost and the pavement became brittle.

  In Example 5, SBBS having a styrene content almost equal to that of SBS used in Example 3 and a viscosity of 25% toluene solution was used. Since the physical properties of Example 3 and Example 5 are almost the same, it can be suggested that the effect of adding SBBS is almost the same as that of SBS.

  In Examples 6 to 12 and Comparative Examples 6 and 7, the styrene content and the 25% toluene solution viscosity are within the ranges specified in the present invention, but changes in physical properties with respect to the addition amount were examined. That is, Examples 6 to 12 and Comparative Examples 6 and 7 use the styrenic thermoplastic elastomer used in Example 5 and have different addition amounts. In Examples 5 and 8, the content of SBBS is the same as 15% by weight, but the content ratios of propane deasphalted asphalt and extract in the base asphalt are different.

  The amount of SBBS added in Examples 6 to 12 is within the range defined in the present invention. On the other hand, the amount of SBBS added in Comparative Examples 6 and 7 is outside the range defined in the present invention.

  While Examples 6 to 12 satisfied the target performance, Comparative Examples 6 and 7 did not satisfy the target performance. That is, by using the styrenic thermoplastic elastomer defined in the present invention, the performance target required as a highly durable drainage pavement polymer-modified asphalt can be met by adding 13 to 19% by weight of SBBS. Range. In the case of Comparative Example 6 in which the amount of SBBS added is 12% by weight, the modification effect of SBBS is small, and the physical property values such as the complex elastic modulus and DS value are equivalent to those of the polymer-modified asphalt H type commercial product. End up. On the other hand, it is shown that when the addition amount of SBBS shown in Comparative Example 7 is 20% by weight, the modification effect of SBBS is too great and the viscosity at 180 ° C. is increased to over 2000 mPa · s.

  Moreover, although Example 11 is an example which adds 18 weight% of SBBS, it is shown that a viscosity can be lowered | hung at a stretch rather than Example 12 which adds this 19 weight%. In addition, Example 8 is an example in which 15% by weight of SBBS is added. Compared with Example 7 in which 14% by weight of SBBS is added, the complex elastic modulus and DS value can be improved to a more suitable range. It is shown. For this reason, it has been shown that the amount of SBBS added is desirably 15 to 18% by weight based on the entire asphalt composition.

Claims (2)

With base asphalt,
Styrenic thermoplastic elastomer containing at least one selected from SBS and SBBS having a styrene content of 35 to 70% by weight and a 25% toluene solution viscosity of 150 to 1500 mPa · s: 13 ~ 19 wt%,
A polymer-modified asphalt composition characterized by containing only With base asphalt,
Styrenic thermoplastic elastomer containing at least one selected from SBS and SBBS having a styrene content of 35 to 70% by weight and a 25% toluene solution viscosity of 150 to 1500 mPa · s: 13 ~ 19 wt%,
Anti-peeling agent: 0.3 to 1.0% by weight,
A polymer-modified asphalt composition characterized by containing only