JP5615679B2 - Polymer modified asphalt composition - Google Patents

Description

  The present invention relates to a polymer-modified asphalt composition suitable for application to drainage pavement among polymer-modified asphalt compositions mainly applied to road pavement.

  Conventionally, asphalt has been used in a wide range of fields such as road paving and waterproofing. One of the applications where the asphalt composition is actually applied to road pavement is drainage pavement. Many drainage pavements are also constructed on ordinary roads, greatly contributing 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 high viscosity 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.

  A paving mixture that requires a binder and aggregate such as asphalt needs to melt the binder and cover the aggregate. For this reason, it is necessary to heat to a considerably high temperature in the production and paving from the viewpoint that the binder needs to be melted. In particular, drainage pavement using high viscosity polymer modified asphalt to which a modifier such as thermoplastic elastomer is added at about 10% by weight generally requires heating at around 170 ° C. as a mixing temperature during production. The compaction temperature is also not lower than 130 ° C. For this reason, there has been a problem that a great amount of energy is required for heating the binder during production and paving, and at that time, a greenhouse gas typified by carbon dioxide is generated.

  In addition, pavement mixtures that require binders and aggregates such as asphalt may drop in temperature while being transported to the pavement site after being manufactured at the mixture plant, resulting in binder viscosity. Since the workability will be significantly deteriorated and the handling at the construction site will be reduced, from the viewpoint of improving the handling at the construction site, by further increasing the mixing temperature at the time of production in the compound plant In many cases, measures are taken to prevent deterioration of workability due to cooling during transportation. However, in such a case, when the heating is performed excessively, the viscosity of the asphalt is excessively lowered, and the binder hangs down from the aggregate, resulting in a problem that the amount of the asphalt is less than the designed amount. This has a large porosity and tends to occur in drainage pavement with a large amount of asphalt covering the aggregate, and the difficulty of temperature control during production and pavement has been a problem.

  In order to solve the above-mentioned problems, conventionally, the viscosity of the asphalt binder is lowered to improve the workability when mixing the binder and aggregate, and when the produced mixture is laid on the road. For example, techniques disclosed in Patent Documents 1 to 4 have been proposed.

  However, the technique disclosed in Patent Document 1 can reduce the viscosity by adding lubricating oil or the like to the binder, but has a problem that the asphalt is softened and the strength is not obtained.

  In each of the disclosed technologies of Patent Document 2 and Patent Document 3, a technique of using a wax as a technique for reducing the viscosity of a binder is disclosed, but according to such a method, at a temperature equal to or higher than the softening point of the wax. Although the viscosity can be lowered, the viscosity increases remarkably in the temperature range below the softening point, making temperature management during construction very difficult. Moreover, since wax content increases, there exists a problem that the compatibility of the thermoplastic elastomer in asphalt deteriorates, and storage stability worsens.

  Furthermore, in Patent Document 4, by adding a component that generates a water vapor component during mixing during production, fine bubbles are generated in the binder, and production at a lower temperature is achieved by the bearing effect of the fine bubbles in the binder.・ Technology that enables paving is disclosed, but there are problems that the manufacturing method becomes complicated compared to conventional methods, such as the pavement strength being reduced by fine bubbles, and the method of mixing additives during production. .

JP 2001-072862 A JP 2002-538231 A JP 2002-302905 A JP 2001-640552 A

  The present invention has been devised in view of the above-mentioned problems, and the object of the present invention is to reduce the viscosity of the binder, and at the time of manufacturing the mixture and compacting at the time of execution at a low temperature. Another object of the present invention is to provide a polymer-modified asphalt composition that does not impair the workability and that is excellent in compatibility and can exhibit sufficient strength as 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 reducing the viscosity of the binder and the required strength. We paid attention to the fact that storage stability is obtained. As a result, in the styrenic thermoplastic elastomer, the binder melt viscosity and the flexibility at low temperature when the molecular length for the same molecular weight specified by the styrene content and the 25% toluene solution viscosity is added to the binder, and after paving Inventing a polymer-modified asphalt composition capable of solving the above-mentioned conventional problems by combining two types of styrenic thermoplastic elastomers in order to find out that the strength is affected and to optimize these two characteristics. It came to.

The polymer-modified asphalt composition according to claim 1, wherein the styrene content is in the range of 20 to less than 40 wt%, and the 25% toluene solution viscosity is in the range of 630 to 2100 mPa · s. Containing a second thermoplastic elastomer and a second styrene thermoplastic elastomer having a styrene content in the range of 40 to 60% by weight and a 25% toluene solution viscosity in the range of 170 to 2912 mPa · s, The total of the first styrenic thermoplastic elastomer and the second styrenic thermoplastic elastomer is 8 to 12% by weight based on the entire asphalt composition, and further, the first styrenic thermoplastic elastomer and the second styrenic thermoplastic elastomer. The weight ratio of the styrene-based thermoplastic elastomer is 23:77 to 74:26 .

  The polymer-modified asphalt composition according to claim 2 is characterized by containing 0.3 to 1.0% by weight of an anti-peeling agent.

  The polymer-modified asphalt of the present invention maintains the strength required for drainage pavement, that is, digging resistance (DS value) and aggregate scattering at a low temperature (low-temperature cantabulo loss amount) while maintaining the conventional drainage performance. It can be manufactured and paved even at a temperature lower than 30 ° C compared to polymer modified asphalt for paving, and it is possible to provide a polymer modified asphalt composition with excellent compatibility and high storage stability. It became.

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

  Hereinafter, the polymer-modified asphalt composition to which the present invention is applied has a styrene content in the base asphalt in the range of less than 20 to 40% by weight and a 25% toluene solution viscosity in the range of 150 to 3000 mPa · s. A first styrenic thermoplastic elastomer and a second styrenic thermoplastic elastomer having a styrene content in the range of 40 to 60% by weight and a 25% toluene solution viscosity in the range of 150 to 3000 mPa · s. It is contained and an anti-peeling agent (resin acid or fatty acid amide) is added as necessary.

  The total of the first styrenic thermoplastic elastomer and the second styrenic thermoplastic elastomer is 8 to 12% by weight based on the entire asphalt composition, and the anti-peeling agent is contained in an amount of 0.3 to 1.0% by weight. ing.

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

Styrenic thermoplastic elastomer

  The styrenic thermoplastic elastomer used in the polymer-modified asphalt composition of the present invention is obtained by mixing a first styrenic thermoplastic elastomer defined below and a second styrenic thermoplastic elastomer.

  The first styrenic thermoplastic elastomer has a styrene content in the range of 20 to less than 40% by weight and a 25% toluene solution viscosity in the range of 150 to 3000 mPa · s.

  As an example of the first styrenic thermoplastic elastomer, as long as the above-described conditions are satisfied, there is no particular limitation on the type thereof, and styrene-butadiene-styrene block copolymer (SBS), double in the butadiene block of SBS. Styrene-ethylene / butadiene-styrene block copolymer (SEBS) in which the bond portion is completely hydrogenated, and styrene-butadiene / butylene in which the double bond in the butadiene block of SBS is selectively partially hydrogenated Styrene block copolymer (SBBS), etc., styrene-isoprene-styrene block copolymer (SIS), styrene-ethylene / propylene-styrene with completely hydrogenated double bond part in butadiene block of SIS A block copolymer (SEPS) etc. can be mentioned. Among them, it is preferable to use SBS.

  The first styrene thermoplastic elastomer has a shorter molecular length by lowering the molecular weight of the styrene thermoplastic elastomer having a styrene content of around 30% by weight, which has been used as an asphalt modifier. Thus, the thickening effect given to the asphalt composition is lower than that of the conventional one, the hysteresis loss is increased, and the flexibility at low temperature is increased.

  The styrene content in the first styrenic thermoplastic elastomer needs to be 20% by weight or more to less than 40% by weight and a 25% toluene solution viscosity of 150 to 3000 mPa · s. Preferably, the styrene content is 28 0.5-32.5 wt% and 25% toluene solution viscosity 500-2500 mPa · s, more preferably, the styrene content is 28.5-30.5 wt% and 25% toluene solution viscosity 1300-2000 mPa -S.

  Here, when the styrene content in the first styrenic thermoplastic elastomer is less than 20% by weight, the modification effect caused by styrene is weak, so the mechanical strength given to the asphalt is low, and the modified asphalt composition itself is complex. It is not preferable because mechanical properties such as elastic modulus, DS value, and strength are lowered. On the other hand, when the styrene content in the first styrene-based thermoplastic elastomer is 40% by weight or more, the modification effect brought about by styrene becomes too strong. This is not preferable because the amount of cantabulo loss) and, in turn, the flexibility becomes low.

  Further, when the viscosity of the 25% toluene solution in the first styrene-based thermoplastic elastomer is smaller than 150 mPa · s, it is not preferable because the modification effect cannot be obtained because the molecular weight becomes too low.

  On the other hand, when the viscosity of the 25% toluene solution in the first styrenic thermoplastic elastomer is larger than 3000 mPa · s, the viscosity of the polymer-modified asphalt composition is remarkably increased due to the excessively high molecular weight. It is not preferable because it cannot be produced and paved under a temperature condition lower by 30 ° C. or more than the conventional polymer modified asphalt for drainage pavement.

  The second styrene-based thermoplastic elastomer has a styrene content in the range of 40 to 60% by weight and a 25% toluene solution viscosity in the range of 150 to 3000 mPa · s.

  As an example of the second styrenic thermoplastic elastomer, as long as the above-mentioned conditions are satisfied, there is no particular limitation on the type thereof, and styrene-butadiene-styrene block copolymer (SBS), double in the butadiene block of SBS. Styrene-ethylene / butadiene-styrene block copolymer (SEBS) in which the bond portion is completely hydrogenated, and styrene-butadiene / butylene in which the double bond in the butadiene block of SBS is selectively partially hydrogenated Styrene block copolymer (SBBS), etc., styrene-isoprene-styrene block copolymer (SIS), styrene-ethylene / propylene-styrene with completely hydrogenated double bond part in butadiene block of SIS A block copolymer (SEPS) etc. can be mentioned. Among them, it is preferable to use SBS.

  The second styrene-based thermoplastic elastomer is a polybutadiene having a large amount of linear components by increasing the styrene content of a styrene-based thermoplastic elastomer having a styrene content of around 30% by weight, which has been conventionally used as an asphalt modifier. The ratio of blocks is lowered and the molecular length is shortened, thereby lowering the thickening effect on the asphalt composition compared to the conventional one. Moreover, by increasing the content ratio of the polystyrene block to which bulky aromatic groups are bonded, it becomes possible to improve the rigidity of the styrenic thermoplastic elastomer itself, and the complex elastic modulus of the modified asphalt composition itself. It is possible to improve the mechanical characteristics such as the DS value and the strength.

  The styrene content in the second styrenic thermoplastic elastomer needs to be 40 to 60% by weight, and the 25% toluene solution viscosity is 150 to 3000 mPa · s, and preferably the styrene content is 40 to 55% by weight. And 25% toluene solution viscosity 150-1500 mPa * s, More preferably, styrene content is 40-46 weight% and 25% toluene solution viscosity 150-1000 mPa * s.

  Here, when the styrene content in the second styrene-based thermoplastic elastomer is 40% by weight or less, the proportion of the butadiene block increases and the viscosity increases. Therefore, workability at a temperature lower than that of the current product is deteriorated, making the mixture very difficult, and workability is also deteriorated. On the other hand, if the styrene content exceeds 60% by weight, styrene has a higher glass transition temperature than straight-chain components such as butadiene and is not preferable because it tends to break at low temperatures and deteriorates the low-temperature properties. . Furthermore, 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 a deterioration in mechanical properties.

  Further, when the viscosity of the 25% toluene solution in the second styrenic thermoplastic elastomer is smaller than 150 mPa · s, the molecular weight becomes too low, so that the modification effect cannot be obtained, which is not preferable. On the other hand, when the viscosity of the 25% toluene solution in the second styrenic thermoplastic elastomer is greater than 3000 mPa · s, the viscosity of the asphalt composition is remarkably increased due to the excessively high molecular weight. This is not preferable because it cannot be produced or paved even at a temperature of 30 ° C. or more lower than that of polymer modified asphalt for drainage pavement.

  In the present invention, both are styrene-based thermoplastic elastomers having a low 25% toluene solution viscosity, each of which is excellent in low-temperature properties, while the first styrene-based thermoplastic elastomer having low rigidity is excellent in rigidity, but is flexible. By combining two types of thermoplastic elastomers, a second styrenic thermoplastic elastomer that is low in low-temperature properties and lowering the overall viscosity compared with the commercially available polymer-modified asphalt H type, In addition, the present inventors have found a composition for satisfying the well-balanced performances of low temperature characteristics and mechanical characteristics of an asphalt composition while enabling production and paving even at a temperature as low as 30 ° C. or higher.

  Here, the weight ratio of the first styrenic thermoplastic elastomer to the second styrenic thermoplastic elastomer is 23:77 to 83:17, preferably 39:61 to 74:26, and more preferably 55: It is the range of 45-65: 35.

  When the weight ratio of the first styrenic thermoplastic elastomer is less than 23% by weight with respect to the sum of the two, the flexibility imparted to the asphalt composition is not sufficient, and it cannot be used in a low temperature range. On the other hand, when the weight ratio of the second styrenic thermoplastic elastomer exceeds 77% by weight with respect to the total of both, the low-temperature properties are deteriorated. On the other hand, when the weight ratio of the first styrenic thermoplastic elastomer is more than 83% by weight based on the total of both, the viscosity at 140 ° C. becomes high and it becomes difficult to prepare a mixture. Further, when the weight ratio of the second styrenic thermoplastic elastomer is less than 17% by weight with respect to the sum of the two, sufficient strength cannot be obtained as indicated by the complex elastic modulus. For this reason, it is desirable that the weight ratio of the first styrenic thermoplastic elastomer and the second styrenic thermoplastic elastomer is 23:77 to 83:17.

  Further, by setting the ratio of the first styrenic thermoplastic elastomer and the second styrenic thermoplastic elastomer to the range of 39:61 to 74:26, more preferably 55:45 to 65:35, The weak point can be complemented better, the pavement strength is sufficient, and the composition can be excellent in low-temperature properties.

  The total of the first styrenic thermoplastic elastomer and the second styrenic thermoplastic elastomer is 8 to 12% by weight, preferably 9 to 10% by weight, based on the entire asphalt composition. This is generally within such a range from the viewpoint of the blending amount used for polymer-modified asphalt for drainage pavement. (For example, Tomoko Koyanagi, Technical Trends of Polymer Modified Asphalt, Modified Asphalt No. 35, issued on July 9, 2010, Takahiro Kitani, Environmental Contribution of Polymer Modified Asphalt, Modified Asphalt No. 33, 2009 (Issued on March 10)

  When the total amount of the first styrenic thermoplastic elastomer and the second styrenic thermoplastic elastomer is small relative to the entire asphalt composition, the modification effect is low and mechanical properties cannot be obtained. Less is. On the other hand, when the blending amount is large, the reforming effect is high and the mechanical properties are excellent, but the thickening effect is high and the intended workability cannot be obtained. In addition, the compatibility is deteriorated, and the quality is likely to deteriorate during heating and storage.

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 40/60 to 100/120 equivalent products can be used.

  In general, the lower the penetration grade, the better the mechanical strength represented by the DS value, but the lower the low temperature properties represented by the bending work amount and the 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 base asphalt content in the entire asphalt composition is desirably 87 to 92% 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 bending indicating low temperature properties. Although it is determined in consideration of the work amount and bending stiffness, the content of the extract with respect to the entire asphalt composition is preferably 18 to 30% by weight within the range examined in the present invention.

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.

  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.

  Some anti-peeling agents also have a performance as a lubricant, and in addition to the above-described anti-peeling effect, these act as a lubricant that improves compaction during construction and rolling.

  The fatty acid or fatty acid amide is added to function as a peeling inhibitor and a lubricant. Examples of fatty acids include, but are not limited to, saturated fatty acids such as stearic acid, palmitic acid, and myristic acid, and unsaturated fatty acids such as oleic acid, linoleic acid, and ricillenoic acid.

  Fatty acid amides are represented by, for example, stearic acid amide and ethylenebisstearic acid amide (EBS), but are not limited thereto.

  If the content of the fatty acid or fatty acid amide is less than 0.3% by weight, the effect is not sufficient, and the function cannot be improved as an anti-peeling agent as a final product and a lubricant. On the other hand, when the content of the fatty acid or fatty acid amide exceeds 1% by weight, not only the effect of improving the function as a peeling preventing agent and a lubricant is saturated, but also an expensive fatty acid, or There arises a problem that the raw material cost is remarkably increased due to an increase in the amount of fatty acid amide added. That is, even if the content of fatty acid or fatty acid amide exceeds 1% by weight, the function improvement as a peeling inhibitor and lubricant is not significantly improved, but on the contrary, it is disadvantageous in terms of raw material cost. Become.

  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 Tables 1 to 4 for samples obtained for experimental examination, penetration (25 ° C.), softening point, viscosity (140 ° C.), complex elastic modulus (60 ° C.), A property test consisting of items of bending work (−20 ° C.), bending stiffness (−20 ° C.), and separation test (140 ° C.) is performed. In addition, a mixture performance test including items of DS value (60 ° C.), low temperature cantabulo loss (−20 ° C.), and sagging amount (140 ° C.) is performed. 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 (140 ° C.) was measured under the conditions of JPI-5S-54-99 “Viscosity test method using asphalt-rotary viscometer” at a measurement temperature of 140 ° C., a used spindle SC4-21, and 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 (140 ° 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 700 Pa or more, preferably 1000 Pa or more. The asphalt composition exhibiting such a value has a DS value described later of 6000 times / mm, more preferably 9000 times. A high value of / mm is likely to be obtained. 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.

  The bending work (−20 ° C.) and bending stiffness (−20 ° C.) are measured by the binder bending test method (P49-53) introduced in the modified asphalt pocket guide (Japan Modified Asphalt Association, issued in January 2007). ) Was used.

  The binder bending test mainly evaluates the applicability of drainage pavement asphalt in snowy and cold regions. The bending work (−20 ° C.) is 100 kPa or more, more preferably 400 kPa or more. The bending stiffness (−20 ° C.) is 400 MPa or less, more preferably 100 MPa or less. If this value is not satisfied, breakage or the like occurs in a low temperature region, and it cannot be used particularly in a snowy cold region.

  In the separation test (140 ° C.), the asphalt composition (about 250 g) of the present invention was injected 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 140 ° C. Heated for 48 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 upper softening point and the lower softening point is taken, that is, the difference absolute value of the softening point is 3 or less. Therefore, in Tables 1 to 4, when the difference absolute value of the softening points is 3 or less, it is evaluated as ◯, and when it exceeds 3, it is evaluated as x.

  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 aggregates shown in Table 5 and making the amount of asphalt in the mixture 5.0% by weight. A 5 cm long sheet-like specimen was used in accordance with the wheel tracking test method stipulated 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. In the above-mentioned pavement survey / test method manual, when the DS value is 6000 times / mm or more, the DS value is reported to be 6000 times / mm or more, but in the present invention, it was actually obtained. DS values were used. Further, in consideration of the result of the complex elastic modulus, a desirable DS value is set to 5000 times / mm or more, preferably 7000 times / mm 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 (3).

  As an index of aggregate scattering resistance in a low temperature range, a loss rate of −21.4% or less in a low temperature cantabulo test at −20 ° C. is desirable. This is a value of a commercial product when the same aggregate is used, and if it is less than this, it is suggested that the aggregate is more easily scattered in a low temperature range than the current product.

  Loss amount (%) = {Specimen weight before test (g) −Specimen weight after test (g)} / Specimen weight before test (g) × 100 (3) )

  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 carried out based on the method described in the pavement investigation and test method manual, and the amount of sagging was computed from Formula (4). 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 (4)

The sagging amount at 140 ° C. is preferably 1.0% or less. When exceeding this, at the time of manufacture, the binder hangs down from the aggregate during transportation, and the designed pavement cannot be paved.

(About Examples 1-18 and Comparative Examples 1-9)

  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, SBBS, and SEBS as styrenic thermoplastic elastomers as modifiers will be described in detail. do.

  The sample which consists of a propane deasphalting asphalt, an extract, a styrene-type thermoplastic elastomer, and a peeling inhibitor which consists of the compounding ratio shown in Examples 1-18 of Tables 1-4 and Comparative Examples 1-9 was prepared.

As for the properties of the used propane deasphalting asphalt, the typical properties are 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 . 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.

  Tables 1 to 4 show the styrenic thermoplastic elastomers used. There are 11 types of SBS with different styrene contents and 25% toluene solution viscosity, one type for SBBS (partial hydrogenation), and three types for SEBS (complete hydrogenation), for a total of 15 types. Among the total 15 types of styrenic thermoplastic elastomers shown in Tables 1 to 4, the first to the sixth stage from the top is the first styrenic thermoplastic elastomer, and the sixth stage and below from the top are the second styrene series. It is a thermoplastic elastomer.

  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 25% toluene solution viscosity used the method described in Unexamined-Japanese-Patent No. 2008-31267 etc., for example. That is, a solvent in which toluene is used and a predetermined sample dissolved in 25% by weight of the solution is measured at 25 ° C. with a Brookfield (BL) viscometer.

  The resin acid used was used as an anti-peeling agent and compatibilizer for aggregates, and a disproportionated gum rosin having an acid value of 156 (mg KOH / g: JIS K0070) and a softening point of 77.0 ° C. (JIS K2207). It is. 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.

  Further, the fatty acid amide used was used as an anti-peeling agent and a lubricant for the aggregate, and was ethylene bis stearic acid amide (EBS), with a content of 0.5% by weight based on the entire composition.

  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, the penetration (0.1 mm), softening point (° C.), viscosity at 140 ° C. (mPa · s), complex elastic modulus G ^* , bending work (kPa), bending stiffness (MPa), 140 ° C. A test is conducted for each item of a separation test for 48 hours (O if the difference in absolute value of the softening point at 25 ° C is 3 or less, x if it exceeds 3). In the mixture performance test, the DS value at 60 ° C., the low-temperature cantabulo loss amount at −20 ° C., and the sagging amount at 140 ° C. are tested.

  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 the quality standards for polymer modified asphalt for drainage pavement established by the Japan Modified Asphalt Association. The penetration (25 ° C) is 40 or higher, and the softening point is 80 ° C or higher. Meet.

  The viscosity (140 ° C.) is 2000 mPa.s. s or less. If this value is exceeded, the viscosity will be too high, and construction at that temperature will be difficult.

  The target value of the asphalt stiffness in the high temperature range was set to 700 or more when the complex elastic modulus (G *) measured by DSR (60 ° C.) was used as an index. If it is less than this value, the rigidity is low and sufficient pavement strength cannot be maintained.

  The target values for the flexibility of asphalt in a low temperature range were a bending work obtained by a binder bending test at -20 ° C. of 100 kPa or more and a bending stiffness of 400 Mpa or less. If this value is not satisfied, breakage or the like occurs in a low temperature region, and it cannot be used particularly in a snowy cold region.

  Stability during heat storage was measured by a separation test (140 ° C.). The absolute value of the difference value between the upper softening point and the upper softening point and the lower softening point was taken, and when the difference absolute value was 3 or less, it was evaluated as ◯.

  As an index of the difficulty of rutting in summer, the DS value obtained from the wheel tracking test result was set to 5,000 times / mm or more. It is a value required for drainage pavement, and if it is less than this, it indicates that rutting is easy.

  As an index of aggregate scattering resistance in a low temperature range, a loss rate of −21.4% or less in a low temperature cantabulo test at −20 ° C. is desirable. This is a value of a commercial product when the same aggregate is used, and if it is less than this, it is suggested that the aggregate is more easily scattered in a low temperature range than the current product.

The sagging amount at 140 ° C. is preferably 1.0% or less. When exceeding this, at the time of manufacture, the binder hangs down from the aggregate during transportation, and the designed pavement cannot be paved.

  In Examples 1 to 18, 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 both defined in the present invention. It is within the range of the first styrenic thermoplastic elastomer and the second styrenic thermoplastic elastomer.

  Thereby, as for all Examples 1-18, 140 degreeC viscosity is 2000 mPa * s or less, the amount of sagging loss in 140 degreeC is 1.0 weight% or less, and also maintains the intensity | strength required as road pavement simultaneously. From the viewpoint, the complex elastic modulus G * is 700 Pa or more, the DS value is 5000 times / mm or more, the bending work by a bending test (−20 ° C.) is 100 kPa or more, and the bending stiffness is 400 MPa or less.

  On the other hand, Comparative Example 1 is a property of polymer modified asphalt H type which is generally used. In Comparative Examples 2 to 9, 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 range of the first styrenic thermoplastic elastomer and the second styrenic thermoplastic elastomer defined in the present invention.

  In the first styrenic thermoplastic elastomer, SBS having a styrene content of 31% and a 25% toluene solution viscosity of 4000 mPa · s is commonly used as a raw material for polymer-modified asphalt.

  Other styrenic thermoplastic elastomers have been selected for study to solve the problems of the present invention.

  In Comparative Examples 2 to 4, the content of the styrenic thermoplastic elastomer is within the range specified in the present invention, but the intended performance cannot be exhibited, and the bending work amount or bending stiffness is particularly low.

  As a result of using a low molecular weight SBS having a styrene content of 30% and a toluene solution viscosity of 1700 mPa · s shown in Comparative Example 2, although the viscosity is lowered and the low-temperature properties are improved as compared with the current product, the rigidity, DS The value drops significantly and the performance as a paving body cannot be satisfied.

  As a result of using SBBS having a styrene content of 45% and a 25% toluene solution viscosity of 172 mPa · s shown in Comparative Example 3, although the viscosity is decreased, the rigidity and the DS value are improved as compared with the current product, the low temperature property The target performance is not satisfied.

  The same results as in Comparative Example 3 were obtained in the results shown in Comparative Example 4 in which 5% by weight of SBBS having a styrene content of 45% and a 25% toluene solution viscosity of 172 mPa · s and 5% by weight of commonly used SBS were used. Met. That is, low temperature properties could not be improved by using general SBS together.

  On the other hand, in Examples 1 to 3, low-temperature properties are improved by combining with low molecular weight SBS having a styrene content of 30% and a toluene solution viscosity of 1700 mPa · s.

  In Example 1, SBBS having a styrene content of 45% and a 25% toluene solution viscosity of 172 mPa · s as 5% by weight as the second styrene-based thermoplastic elastomer, and the styrene content as the first styrene-based thermoplastic elastomer 30% low molecular weight SBS having a toluene solution viscosity of 1700 mPa · s was combined. As a result, the viscosity of the polymer-modified asphalt H-type commercial product shown in Comparative Example 1 was reduced to half or less, and the rigidity, DS value, and low-temperature properties were within the target ranges.

  In Example 2, the blending of the styrenic thermoplastic elastomer was the same as in Example 1, but 0.5% by weight of ethylenebisstearic acid amide (EBS) was added as an anti-peeling agent. In addition to the effect of preventing peeling, EBS also has an effect as a lubricant and can slightly reduce the viscosity. As a result, the viscosity could be further reduced while maintaining other properties.

  In Example 3, the second styrene-based thermoplastic elastomer has a styrene content of 45%, a 25% toluene solution viscosity of 170 mPa · s SBS 5% by weight, and the first styrene-based thermoplastic elastomer has a styrene content of 30% by weight. A low molecular weight SBS having a toluene solution viscosity of 1700 mPa · s was combined. This also met the target performance.

  In Examples 4 to 7 and Comparative Examples 5 and 6, the proportions of the first and second styrenic thermoplastic elastomers were examined.

  In each of Examples 4 to 7 and Comparative Examples 5 and 6, a low molecular weight SBS having a styrene content of 30% by weight and a toluene solution viscosity of 1700 mPa · s as a first styrene thermoplastic elastomer, and a second styrene The thermoplastic elastomer is a combination of SBS having a styrene content of 45% and a 25% toluene solution viscosity of 170 mPa · s, both of which are within or outside the range defined in the present invention. .

  While Examples 4 to 7 satisfied the target performance, Comparative Examples 5 and 6 did not satisfy the target performance. That is, when the blending ratio of either the first styrenic thermoplastic elastomer or the second styrenic thermoplastic elastomer is less than 2.5% by weight, the respective defects such as deterioration of low-temperature performance and reduction of rigidity are obvious. The target performance was not satisfied. In addition, between Examples 4-7, it turns out that the direction of Example 7 is superior to Example 4 especially in the point of the bending work amount. That is, it can be seen that the low temperature properties can be drastically improved by setting the content ratio of the first styrenic thermoplastic elastomer to be equal to or higher than that of the second styrenic thermoplastic elastomer as in Example 7.

  In Examples 8 to 12 and Comparative Example 7, the content ratio of the first styrenic thermoplastic elastomer was 7.5% by weight, and the content ratio of the second styrenic thermoplastic elastomer was 2.5% by weight. Thus, the styrene content ratio and the toluene solution viscosity of the first styrenic thermoplastic elastomer are changed and examined.

  In Examples 9, 10 and 11, the styrene content of the first styrenic thermoplastic elastomer is in the range of 28.5 to 30.5% by weight, and the 25% toluene solution viscosity is 1300 to 2000 mPa · s. Therefore, the viscosity is low while maintaining the digging resistance (DS value) and the low-temperature cantabulo loss amount.

  While Examples 8 to 12 satisfied the target performance, Comparative Example 7 did not satisfy the target performance. That is, for the first styrene-based thermoplastic elastomer, when the viscosity of the 25% toluene solution becomes 3000 mPa · s or more, the increase in the viscosity becomes remarkable, and the production / paving at 140 ° C., which is the object of the present invention, is achieved. It became difficult. In addition, the low-temperature properties were significantly deteriorated.

  In Examples 11, 13 to 18 and Comparative Examples 8 and 9, the content ratio of the first styrenic thermoplastic elastomer was 7.5% by weight, and the content ratio of the second styrenic thermoplastic elastomer was 2.5% by weight. %, The styrene content ratio of the second styrenic thermoplastic elastomer and the viscosity of the toluene solution are changed.

  While Examples 11 and 13 to 18 satisfied the target performance, Comparative Examples 8 and 9 failed to satisfy the target performance. That is, the second styrenic thermoplastic elastomer loses its flexibility remarkably when the SBS has a styrene content ratio of 75% by weight or more, and SEBS has a styrene content of 67% by weight or more. As a result, the low temperature property cannot be improved even when low molecular weight SBS is used. Moreover, it has been shown that due to the decrease in flexibility, the pavement becomes brittle and the DS value is significantly reduced.

  Among them, Examples 11, 13, 14, 17, and 18 have a styrene content in the range of 40 to 46% by weight and a 25% toluene solution viscosity in the range of 150 to 1000 mPa · s. Moreover, it is particularly excellent in the low temperature property shown in the low temperature cantabulo loss amount. Further, in these properties, there was no significant difference in properties due to the difference in the types of styrene thermoplastic elastomers such as SBS, SEBS and SBBS.

Claims (2)

A first styrenic thermoplastic elastomer having a styrene content in the range of 20 to less than 40% by weight and a 25% toluene solution viscosity in the range of 630 to 2100 mPa · s;
A second styrenic thermoplastic elastomer having a styrene content in the range of 40 to 60% by weight and a 25% toluene solution viscosity in the range of 170 to 2912 mPa · s,
The total of the first styrenic thermoplastic elastomer and the second styrenic thermoplastic elastomer is 8 to 12% by weight based on the entire asphalt composition, and further, the first styrenic thermoplastic elastomer and the first styrenic thermoplastic elastomer. A polymer-modified asphalt composition having a weight ratio of 2 to a styrene-based thermoplastic elastomer of 23:77 to 74:26 .   2. The polymer-modified asphalt composition according to claim 1, further comprising 0.3 to 1.0% by weight of an anti-peeling agent.

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