JP6199331B2 - Asphalt modifier and method for producing asphalt mixture using the same - Google Patents

Description

  The present invention relates to an asphalt modifier for improving the physical properties of an asphalt mixture, and a method for producing an asphalt mixture using the same.

  Traditionally, asphalt is liquefied at high temperatures to improve processability, while solidifying at room temperature or low temperature to increase bond strength and excellent strength, road paving materials, roofing materials, sealing materials It is used for a wide range of applications such as coating materials. However, such high temperature dependence of asphalt is both an advantage and a disadvantage.

  For example, when asphalt is used as a road pavement, deformation due to plastic flow of asphalt is likely to occur at high temperatures in summer. On the other hand, in winter, there were problems such as easy cracking due to curing and severe wear due to tire chains.

  In addition, drainage pavement (open-graded pavement), which is a high-performance pavement, uses an open-graded porous asphalt mixture so that rain can be drained quickly. Compared to conventional asphalt pavement, breakage of aggregates, wrinkles, and surface wear is likely to occur. Therefore, asphalt is required to improve various physical properties, and in particular, it is required to have excellent flow resistance in an asphalt mixture in which aggregates and the like are mixed, and excellent binder properties represented by toughness and tenacity.

  In view of the above problems, for example, Patent Documents 1 to 5 listed below disclose modifiers that modify asphalt. That is, these documents include thermoplastics such as ethylene-vinyl acetate copolymer (EVA), ethylene-ethyl acrylate copolymer (EEA), and ethylene-butyl acrylate copolymer (EBA) as asphalt modifying components. Resin, synthetic rubber such as styrene / butadiene random copolymer rubber (SBR), chloroprene rubber (CR), styrene-butadiene block copolymer (SBS), styrene-isoprene block copolymer (SIS), and Thermoplastic elastomers such as these modified maleic anhydrides are mentioned, and the asphalt is modified by mixing the asphalt with a modifier containing these asphalt modifying components.

Japanese Patent Laid-Open No. 9-235470 Japanese Patent Laid-Open No. 10-338559 Japanese Patent Laid-Open No. 11-60961 JP 2001-247770 A JP 2004-346119 A

  However, the modification with only the thermoplastic resin has the problem that the elasticity of asphalt is increased, but the properties such as elongation ability and adhesion are inferior. Further, the modification with only rubber has a problem that the softening point and flow resistance are not sufficiently improved. Further, in the modification only with the thermoplastic elastomer, the thermoplastic elastomer has poor solubility in asphalt, and therefore, the heating and stirring state must be maintained for a long time, and much time and labor are required for mixing and melting.

  On the other hand, Patent Documents 1 to 5 describe that a plurality of types of asphalt modifying components are mixed, but the properties differ depending on the material among thermoplastic resins and thermoplastic elastomers, and any combination is possible. Satisfactory physical properties are not obtained, and the mixing ratio is also important. In addition, even with the same reforming component, the results obtained differ depending on the grade, but Patent Literature 1 to Patent Literature 5 do not pay attention to this point. With this, a sufficient reforming effect cannot be obtained.

  Conventionally, the asphalt modifier is often mixed in advance by a premix method in which an asphalt modifier is melted and dispersed, but there is a problem that a special mixing facility is required.

  Therefore, the present invention is to solve the above problems, and an object of the present invention is to provide an asphalt modifier capable of imparting excellent flow resistance and binder properties to asphalt and a method for producing an asphalt mixture using the asphalt mixture. To do.

  As means for that purpose, the asphalt modifier of the present invention contains a styrene-isoprene-styrene block copolymer (SIS) and an ethylene-ethyl acrylate copolymer (EEA). In addition, the content ratio of SIS and EEA is 25:75 to 50:50 in terms of mass ratio, and the content of ethylene as a hard segment in the EEA is 75 to 85% by mass (in other words, the softness in EEA The content of ethyl acrylate as a segment is 25 to 15% by mass).

  In the present invention, “OO to XX” indicating a numerical range means that the upper limit and the lower limit are included. In other words, when it is expressed accurately, it means “more than XX and less than XX”.

  The asphalt modifier, asphalt, aggregate, and the like are preferably mixed by a plant mix method of mixing in an asphalt plant, rather than a premix method in which the asphalt modifier is previously melt-dispersed in asphalt.

  According to the asphalt modifier of the present invention, by using a thermoplastic resin in which a predetermined reforming component is mixed at a predetermined ratio, and a hard segment and a soft segment are in a predetermined balance, Asphalt can be modified by imparting various physical properties in the asphalt mixture, particularly excellent flow resistance and binder properties.

  In addition, if the asphalt modifier, asphalt, aggregate, and the like are mixed by the plant mix method, special mixing equipment such as a premix method is not necessary.

It is a graph which shows the measurement result of dynamic stability. It is a graph which shows the measurement result of toughness and tenacity. It is a measurement result of dynamic stability in Test 2. It is a measurement result of toughness in Test 2. It is a measurement result of tenacity in Test 2.

≪Asphalt modifier≫
The asphalt modifier of the present invention is formed by combining a specific thermoplastic elastomer and a thermoplastic resin.

<Thermoplastic elastomer>
The thermoplastic elastomer is a vinyl aromatic hydrocarbon / conjugated diene block copolymer in detail, and tends to have excellent toughness and tenacity, that is, ductility. Among them, in the present invention, a styrene-isoprene-styrene block copolymer (SIS) is used. Other vinyl aromatic hydrocarbon / conjugated diene block copolymers can be modified to some extent, but various physical properties cannot be modified in a well-balanced manner. On the other hand, SIS among the vinyl aromatic hydrocarbon / conjugated diene block copolymers can improve various physical properties such as flow resistance, toughness, tenacity, etc. in a well-balanced manner in a short mixing time.

  The composition ratio of styrene and isoprene in the SIS is not particularly limited, but it is preferable that the proportion of styrene is smaller in consideration of the relationship with the thermoplastic resin described later. Specifically, the mass ratio of styrene: isoprene is 5:95 to 50:50, preferably 10:90 to 45:55, and more preferably 20:80 to 40:60. This makes it easy to impart good fluid resistance, binder properties such as toughness and tenacity to asphalt.

<Thermoplastic resin>
Thermoplastic resins tend to have excellent dynamic stability (DS), that is, excellent flow resistance. Among them, ethylene-ethyl acrylate copolymer (EEA) is used in the present invention. Although other thermoplastic resins can be modified to some extent, various physical properties cannot be modified in a well-balanced manner. On the other hand, if it is predetermined EEA among thermoplastic resins, various physical properties such as fluid resistance, toughness and tenacity can be improved in a well-balanced manner.

  The composition ratio of ethylene and ethyl acrylate in EEA is ethylene: ethyl acrylate = 75: 25 to 85:15 by mass ratio. In other words, the ethylene content in EEA is 75 to 85% by mass, and the ethyl acrylate content is 25 to 15% by mass. If the balance between ethylene and ethyl acrylate is out of this range, the desired modification effect cannot be obtained.

  The blending ratio of SIS and EEA in the asphalt modifier is SIS: EEA = 25: 75 to 50:50 in mass ratio. If the blending ratio of SIS and EEA is out of this range, the desired modification effect cannot be obtained.

<Other additives>
The asphalt modifier of the present invention uses only SIS and EEA as the thermoplastic elastomer and thermoplastic resin conventionally used as the modifying component, but other additions within the range that does not impair the effects of the present invention. An agent may be contained. However, it is preferable that no rubber component is contained. This is because it directly affects the reforming effect of SIS and EEA, and the balance of these reforming effects may be lost and the physical properties may be lowered. Specific examples of other additives include process oil, tackifier, anti-blocking agent, antioxidant, ultraviolet absorber, light stabilizer, inorganic filler, etc., alone or in combination of two or more. Can be added.

  Examples of the process oil include vegetable oils such as rice bran oil and soybean oil, animal oils such as fish oil and whale oil, and petroleum heavy hydrocarbon oils such as cylinder oil and lubricating oil.

  Examples of the tackifying resin include coumarone / indene resin, phenol resin, pt-butylphenol / acetylene resin, phenol / formaldehyde resin, terpene / phenol resin, polyterpene resin, xylene / formaldehyde resin, C5 petroleum resin, and C9. And petroleum-based petroleum resins, dicyclopentadiene resins, polybutenes, rosins, and their hydrogenated products or modified products with maleic anhydride. Among these, C9 petroleum resin is particularly suitable.

  The anti-blocking agent may be organic or inorganic. Examples of the organic anti-blocking agent include higher fatty acid monoamides such as stearic acid amide, oleic acid amide, lauric acid amide, valmitic acid amide, erucic acid amide, and behenic acid amide; methylene bis stearic acid amide, ethylene bis stearic acid amide Higher fatty acid bisamides such as ethylene bisoleic acid amide and ethylene bislauric acid amide; N-stearyl oleic acid amide, N-stearyl erucic acid amide, N-stearyl stearic acid amide, N-oleyl stearic acid amide, distearyl adipic acid Complex higher fatty acid amides such as amides; lauric acid, myristic acid, palmitic acid, margaric acid, stearic acid, behenic acid, oleic acid, linolenic acid, α-eleostearic acid, β-eleostearic acid, α- Lithium salts such Norein acid, sodium salt, potassium salt, magnesium salt, calcium salt, barium salt, zinc salt, aluminum salts, higher fatty acid salts such as iron salts. Examples of the inorganic anti-blocking agent include silica, calcium carbonate, magnesium carbonate, calcium sulfate, aluminum hydroxide, zinc oxide, talc and clay.

  Examples of the antioxidant include hindered phenol-based, sulfur-based and phosphoric acid-based antioxidants. Examples of the ultraviolet absorber include benzophenone-based ultraviolet absorbers. Examples of the light stabilizer include hindered amine light stabilizers. Examples of the inorganic filler include glass beads, silica, and carbon black.

  The asphalt modifier may be produced by a conventional method, for example, mixing each of the above components using a mixer such as a heat melting kettle, a roll mill, a single screw extruder, a twin screw extruder, a Henschel mixer, etc. It can be molded by a press, pelletizer, extrusion molding machine, processing molding machine or the like. The heating and mixing is usually performed in a temperature range of 50 to 250 ° C, preferably 100 to 200 ° C.

  The shape of the asphalt modifier is not particularly limited and can be used in any shape. For example, any of a pellet shape, a string shape, a plate shape, a block shape and the like may be used, but a pellet shape is preferable in terms of solubility in asphalt. Pelletization of the asphalt modifier can be achieved by mixing the above components, extruding them into a strand with an extruder, etc., cooling with cold water, etc., and then chopping with a pelletizer.

≪Asphalt mixture≫
An asphalt mixture as a road pavement material can be obtained by mixing the asphalt modifier with asphalt together with aggregates or the like as necessary. As the asphalt, a known one that has been conventionally used for road pavement can be used without any particular limitation. Specifically, straight asphalt, semi-blown asphalt, blown asphalt, cutback asphalt, recycled asphalt, and the like can be used. These asphalts can be used alone or in combination of two or more.

  The asphalt modifier may be mixed in an amount of 1 to 50 parts by weight, preferably 2 to 30 parts by weight, more preferably 3 to 10 parts by weight with respect to 100 parts by weight of asphalt. When the mixing amount of the asphalt modifier is less than 1 part by weight with respect to 100 parts by weight of asphalt, the asphalt modification effect is not substantially recognized. On the other hand, when the amount exceeds 50 parts by weight, the viscosity is too high and the workability of the asphalt mixture is deteriorated, which is extremely disadvantageous economically.

  When the asphalt mixture is used for road pavement, the aggregate is usually often mixed. Aggregates include those for fine-grained, fine-grained or coarse-grained mixtures used for general road pavements, or for open-grained mixtures used for permeable pavement, drainage pavement, sound-absorbing pavement, etc. is there. Specific examples include crushed stone, crushing stone, gravel, sand, stone powder, talc, calcium carbonate, and the like. Moreover, the asphalt reproduction | regeneration aggregate manufactured by grind | pulverizing the waste material of the existing pavement may be used. These aggregates can be used alone or in combination of two or more.

  In addition to the aggregate, other additives can be added to the asphalt mixture. Specific examples of additives include, for example, anti-peeling agents such as slaked lime, amines and amides, fibrous reinforcing materials such as methylcellulose and polyvinyl alcohol, elasticity improvers, viscosity reducing agents, viscosity improvers, fillers, and pigments , Softeners, antioxidants, ultraviolet absorbers, light stabilizers and the like.

≪Method for manufacturing asphalt mixture≫
The asphalt mixture obtained by mixing the asphalt modifier and asphalt and aggregates blended as necessary is preferably a plant mix system in which these are mixed in an asphalt plant. This is because the premix method in which the asphalt modifier and asphalt are mixed and prepared in advance requires special mixing equipment and requires labor for mixing work. The plant mix method is advantageous in that there is no such problem. As the plant mix system, for example, (a) a method of mixing aggregates and heated asphalt in advance and then adding and mixing the asphalt modifier, (b) aggregate, heated asphalt and asphalt modifier (C) Aggregate and the asphalt modifier are mixed in advance, and then heated asphalt is added and mixed.

  Since the asphalt mixture in which the asphalt modifier according to the present invention is mixed is excellent in toughness and tenacity, the aggregate is difficult to peel and fall off from the asphalt mixture. Further, since it is excellent in physical strength such as fluid resistance, it is difficult to cause damage such as wrinkles and surface wear.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, this invention is not limited only to these Examples.

<< Test 1 >>
First, the modification effect by the asphalt modifier which combined the thermoplastic elastomer and the thermoplastic resin as shown in Table 1 (mass ratio 1: 1) was compared and examined. The details of the various thermoplastic elastomers and thermoplastic resins shown in Table 1 are as follows.
SIS: Styrene-isoprene-styrene block copolymer (styrene content 15% by mass)
SBS: Styrene-butadiene-styrene block copolymer (styrene content 30% by mass)
EEA (1): ethylene-ethyl acrylate copolymer (ethylene content 82% by mass)
EEA (2): ethylene-ethyl acrylate copolymer (ethylene content 75% by mass)
EEA (3): ethylene-ethyl acrylate copolymer (ethylene content 65 mass%)
EVA: ethylene-vinyl acetate copolymer (ethylene content 82% by mass)

  The influence on the ductility (toughness tenacity) and flow resistance (dynamic stability) of the asphalt modifiers of the above Examples and Comparative Examples was measured as follows.

(Dynamic stability (DS))
The asphalt mixture was adjusted in a plant mix system for dynamic stability (DS) measurements. Specifically, aggregates for dense-graded asphalt mixture previously heated to 190 ° C. (38% by weight of crushed stone No. 6 in all aggregates, 20% by weight of crushed stone No. 7, 18% by weight of coarse sand, 18% by weight of fine sand, stone powder 6 wt%) 94 wt% was kneaded with a pug mill mixer for 10 seconds and then heated to 170 ° C. 5.77 wt% of straight asphalt (60/80) and the asphalt modifiers of the above examples and comparative examples Was added in an amount of 0.23% by weight (ratio of 4 parts by weight of asphalt modifier with respect to 100 parts by weight of straight asphalt), and further mixed for 50 seconds to obtain a test asphalt mixture. The asphalt mixture was immediately put into a mold, and after 5 reciprocations with a roller compactor at a linear pressure of 29.4 kN, a rubber plate was placed on the surface of the test specimen and rolled back and forth 25 times to obtain a test specimen. In addition, the dynamic stability (DS) was calculated by performing a wheel tracking test at 60 ° C. according to the method described in “Handbook of Pavement Test Method” edited by the Japan Road Association. These results are shown in FIG.

(Toughness and Tenacity)
A modified asphalt prepared by mixing 4 parts by weight of the asphalt modifiers of the above Examples and Comparative Examples with respect to 100 parts by weight of straight asphalt (60/80) was prepared. It measured at 25 degreeC according to the method described in "Test method manual." These results are shown in FIG.

  From the results of FIGS. 1 and 2, it was confirmed that when SIS and EEA were combined and the ethylene content in EEA was 75 to 85% by mass, good results were obtained in both flow resistance, toughness and tenacity. .

  On the other hand, in Comparative Example 1, the ethylene content in the EEA was too low, so the toughness and tenacity were high, but the flow resistance was low. Although the comparative example 2 used EEA with high ethylene content, since SBS was used, toughness and tenacity were low. In Comparative Example 3, SIS was used, but because of the combination with EVA, the modification effect as much as the combination of SIS and EEA was not obtained. Since Comparative Example 4 also uses SBS, the toughness and tenacity were still low. Comparative Example 5 was a combination of SIS and SBS, and no thermoplastic resin was used, so the toughness and tenacity were high, but the flow resistance was low.

<< Test 2 >>
From the above test, it was confirmed that the combination of SIS and predetermined EEA had the highest reforming effect. Then, the influence on the reforming effect by the blending balance of SIS and EEA was subsequently compared. In this test, the above EEA (1) was used as the thermoplastic resin, and the test was performed except that the blending ratio of SIS and EEA in the asphalt modifier (SIS: EEA in weight ratio) was the ratio shown in Table 2. Tested as in 1. These dynamic stability (DS) are shown in FIG. 3, toughness is shown in FIG. 4, and tenacity is shown in FIG.

  From the results of FIGS. 3 to 5, when the ratio of SIS and EEA in the asphalt modifier is 25:75 to 50:50, good reforming effects are obtained in all of the flow resistance, toughness, and tenacity. It was. On the other hand, it was confirmed that when the EEA ratio in the asphalt modifier is less than 50% by mass, the DS is drastically decreased, and at 100% by mass, the tenacity is decreased.

<< Test 3 >>
As described above, from Test 1 and Test 2, it was found that if an asphalt modifier containing SIS and a predetermined EEA in a predetermined ratio is used, various physical properties can be modified in a well-balanced manner as a whole. Accordingly, as confirmation of this, various physical properties when the asphalt modifier of Example 1 was mixed with various asphalts were measured and confirmed.

(Test 3-1)
Tests were performed in the same manner as in Test 1 except that the blending ratio of the asphalt modifier was 5 parts by weight with respect to 100 parts by weight of straight asphalt (60/80). The results are shown in Table 3. In addition, as a comparative data, Table 3 also shows the results of the same test without mixing the asphalt modifier.

(Test 3-2)
The test was conducted in the same manner as in Test 1 except that polymer modified asphalt type II was used as the asphalt and the blending ratio of the asphalt modifier was 3 parts by weight with respect to 100 parts by weight of the polymer modified asphalt type II. The results are shown in Table 4. In addition, as a comparative data, Table 4 also shows the results of a similar test without mixing the asphalt modifier.

(Test 3-3)
Polymer modified asphalt H type was used as the asphalt, and the asphalt mixture was prepared by the plant mix method as follows. 95% by weight of aggregate for open-graded asphalt mixture (85% by weight of No. 6 crushed stone, 10% by weight of fine sand, 5% by weight of stone powder in all aggregates) is kneaded with a pug mill mixer for 10 seconds and then heated to 170 ° C. Heated modified asphalt H type 4.81% by weight and asphalt modifier 0.19% by weight (ratio of 4 parts by weight of asphalt modifier to 100 parts by weight of modified asphalt H type) The mixture was further mixed for 50 seconds to obtain a test asphalt mixture. The asphalt mixture was immediately put into a mold, and after 5 reciprocations with a roller compactor at a linear pressure of 29.4 kN, a rubber plate was placed on the surface of the test specimen and rolled back and forth 25 times to obtain a test specimen. The results of measuring various physical properties are shown in Table 5. As comparative data, Table 5 also shows the results of a similar test without mixing the asphalt modifier.

Various physical properties were measured as follows.
Softening point: Measured according to JIS K 2207.
Marshall stability: Measured according to the method described in “Handbook of Pavement Test Methods” edited by Japan Road Association.
Residual stability: Measured according to the method described in “Handbook of Pavement Test Methods” edited by Japan Road Association.
Cantabro loss rate: measured at 20 ° C. according to the method described in “Handbook of Pavement Test Methods” edited by Japan Road Association.
Torsional aggregate scattering value: Torsional aggregate scattering value after 120 minutes was measured in accordance with the method described in “Pavement Performance Evaluation Method Separate Volume” edited by Japan Road Association.

From the results of Tables 3 to 5, it was confirmed that various physical properties can be reliably improved by using the asphalt modifier of the present invention. In particular, according to the results in Tables 3 and 4, it was confirmed that asphalt could be improved to a grade of one rank higher.

Claims (3)

Styrene - isoprene - styrene block copolymer (SIS), ethylene - containing only ethyl acrylate copolymer (EEA),
The content ratio of the SIS and EEA is 25:75 to 50:50 by mass ratio,
The asphalt modifier whose ethylene content in said EEA is 75-85 mass%. An asphalt mixture containing 3 to 10 parts by weight of the asphalt modifier according to claim 1 with respect to 100 parts by weight of asphalt. The manufacturing method of an asphalt mixture which mixes the asphalt modifier of Claim 1 with asphalt by a plant mix system.

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