JP2010260939A - Styrene-butadiene-based composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a styrene-butadiene-based composition required for producing an asphalt composition capable of improving especially both of stability and strength. <P>SOLUTION: This styrene-butadiene-styrene copolymer (SBS) comprises &ge;1 kind of a 20C polycyclic diterpene among abietic acid, dehydroabietic acid, neoabietic acid, pimaric acid, isopimaric acid and parastoric acid, which is addition-reacted to the double bond of the butadiene block. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a styrene-butadiene composition used as an additive for improving the stability and strength of asphalt applied to road pavements, waterproofing materials, adhesives and the like.

  Conventionally, asphalt has been used in a wide range of fields such as road paving and waterproofing. A styrene-butadiene-styrene copolymer (SBS) is generally used as a reinforcing material for this asphalt. However, when this SBS is dispersed in asphalt, the stability is lowered. In particular, asphalt and SBS are separated immediately at the storage temperature (about 150 to 180 ° C.) at the time of commercial use, and SBS rises. There was a problem of doing.

  The reason is considered that the styrene blocks in the SBS added to the asphalt aggregate. If the styrene blocks are agglomerated, the SBS polymers will agglomerate as shown in FIG. 6 and cannot be uniformly mixed with the asphalt, and the resulting asphalt composition itself It will not be possible to ensure the stability.

  For this reason, when reinforcing this by mixing SBS in this asphalt, conventionally, as a stabilizer for stabilizing SBS in this asphalt, for example, sulfur, polyoxyethylene nonylphenol, peroxide is used. Products, carbon black, aroma oils and the like have been proposed.

  However, sulfur added as a stabilizer involves the risk of hydrogen sulfide generation, and polyoxyethylene nonylphenol should be avoided from the viewpoint of environmental hormones (see, for example, Patent Document 1). Furthermore, organic peroxides have a risk of decomposition or explosion when handled at high temperatures. Moreover, since carbon black is expensive compared with asphalt, it has been a hindrance in actually supplying it to the market as an asphalt product (see, for example, Patent Document 2). Addition of aroma oil can improve stability by dissolving the styrene block in SBS, but it cannot be expected to improve the elastic modulus that can be expressed for the first time due to the presence of styrene block. There is a problem that it is difficult to obtain the expected strength.

  Thus, the demand for a technique for improving both the stability and strength of the asphalt composition has been particularly increased.

JP 2000-53865 A Japanese Patent Laid-Open No. 10-237309

  Therefore, the present invention has been devised in view of the above-described problems, and the object of the present invention is to produce an asphalt composition capable of improving both stability and strength. And a asphalt composition to which the styrene-butadiene composition is added.

  The styrene-butadiene composition according to claim 1, wherein a polycyclic diterpene having 20 carbon atoms having a carboxyl group added to a double bond of a butadiene block in a styrene-butadiene-styrene copolymer (SBS). It is characterized by providing.

  The styrene-butadiene composition according to claim 2 is the invention according to claim 1, wherein the polycyclic diterpene having 20 carbon atoms having a carboxyl group is at least a double of the butadiene block closest to the styrene block. It is characterized by being added to the bond.

  The styrene-butadiene composition according to claim 3 is characterized in that a polycyclic diterpene having 20 carbon atoms having a carboxyl group is added to a butadiene block in a styrene-butadiene-styrene copolymer (SBS). To do.

  A styrene-butadiene composition according to claim 4 is the invention according to claim 3, wherein the polycyclic diterpene having 20 carbon atoms having a carboxyl group is at least the second or third closest carbon to the styrene block. It is added to.

  The styrene-butadiene composition according to claim 5 is the invention according to any one of claims 1 to 4, wherein the polycyclic diterpene having 20 carbon atoms having a carboxyl group is abietic acid or dehydroabieticin. It is one or more of acid, neoabietic acid, pimaric acid, isopimaric acid, and parastrinic acid.

  A styrene-butadiene composition according to claim 6 contains the styrene-butadiene composition according to any one of claims 1 to 5, and the remainder is made of asphalt.

  In the styrene-butadiene composition to which the present invention is applied, a polycyclic diterpene having 20 carbon atoms having a carboxyl group can be added at least in the double bond of the butadiene block closest to the styrene block. The C20 polycyclic diterpene having a carboxyl group has a size 2 to 3 times that of styrene constituting the styrene block. As a result, this C20 polycyclic diterpene having a carboxyl group bears the function of inhibiting the free movement (or separation in some cases) of SBS. When the polycyclic diterpene having 20 carbon atoms having a bulky carboxyl group is in the vicinity of the styrene block, the styrene blocks in the SBS added to the asphalt can be prevented from aggregating with each other. By dispersing the styrene blocks without aggregating, the SBS can be uniformly mixed with the asphalt, and the stability of the resulting asphalt composition itself can be improved.

It is a perspective view which shows typically the measurement part of a dynamic viscoelasticity testing machine. It is a figure which shows the relationship of the complex elastic modulus G ^{* with} respect to the angular frequency (omega) and loss tangent (tan-delta) in an asphalt composition. It is a figure which shows IR spectrum of only abietic acid. It is a figure which shows IR spectrum of a styrene-butadiene type composition. It is another figure which shows the relationship of the complex elastic modulus G ^{* with} respect to the angular frequency (omega) in a asphalt composition, and a loss tangent (tan-delta). It is a figure which shows the example which the styrene blocks in SBS added in asphalt aggregated.

  Hereinafter, a styrene-butadiene composition will be described in detail as the best mode for carrying out the present invention.

  The present inventor conducted intensive experimental research to produce a styrene-butadiene-based composition that can be added to asphalt so as to solve the above-described problems and develop desired stability and strength. As a result, the present inventor made an addition reaction of a carboxylic acid-containing polycyclic diterpene (resin acid) with a styrene-butadiene-styrene copolymer (SBS), thereby the vicinity of the styrene block. It has been found that bulky molecules can be added to the. Specifically, by mixing SBS and a C20 polycyclic diterpene having a carboxyl group, the C20 polycyclic diterpene having a carboxyl group is bonded to the double bond constituting the butadiene block. As a result, it can be solved that the styrene blocks are aggregated, and as a result, the asphalt finally obtained by adding the styrene-butadiene composition to which the present invention is applied to the asphalt. It has been found that the stability of the composition itself can be further improved.

  That is, the styrene-butadiene composition to which the present invention is applied is represented by the following general formula, for example.

In the styrene-butadiene composition to which the present invention is applied, R ₁ is added to the butadiene block in the styrene-butadiene-styrene copolymer (SBS). This R ₁ is added with a C20 polycyclic diterpene (hereinafter also referred to as resin acid) having a carboxyl group.

  Styrene-butadiene-styrene copolymer (SBS) is a so-called thermoplastic elastomer added in asphalt. This SBS has little decrease in physical strength such as elastic modulus and kinematic viscosity due to decomposition at the production and use temperature and processing temperature (about 150 to 210 ° C.) of the asphalt composition, and hydrogenated thermoplasticity described later. It is an inexpensive elastomer compared to an elastomer. Ordinary SBS has a chemical structure in which a butadiene block is sandwiched between styrene blocks as shown in the following chemical formula 2, for example. By adding a resin acid to the double bond constituting this butadiene block, it becomes possible to improve the stability of SBS in the asphalt composition, that is, the tendency to separate and not float and the performance.

  In general, at the same temperature, the density of asphalt is higher than that of SBS. When separation occurs after mixing and dispersing asphalt and SBS, SBS floats on the top surface of the asphalt.

  The resin acid is, for example, a resin acid such as abietic acid, dehydroabietic acid, neoabietic acid, pimaric acid, isopimaric acid, and parastrinic acid, but is not limited thereto, and has 20 carbon atoms having a carboxyl group. Any resin acid under the definition of polycyclic diterpenes is included. These C20 polycyclic diterpenes having a carboxyl group are generally contained in rosin.

  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.

These resin acids can be added by an addition reaction to any double bond of the butadiene block represented by Chemical Formula 2. However, in the styrene-butadiene composition to which the present invention is applied, as shown in Chemical Formula 1, in the butadiene block, the resin acid is added at the double bond in the block A ₁ and the block A ₂ closest to the styrene block. An example will be described.

Here, in the blocks A ₁ and A ₂ in the butadiene block, when the carbon adjacent to the styrene block is changed to C ₁ , C ₂ , C ₃ , and C ₄ , the resin acid R ₁ is added to the carbon C ₂ . It will be. However, this resin acid R ₁ may be added not only to this carbon C ₂ but also to carbon C ₃ .

The chemical formula 3 below shows an example in which resin acids R ₁ is added at a carbon other than the block A _1, A ₂ in the butadiene block.

That is, the resin acid R ₁ may be added at any carbon other than the blocks A ₁ and A ₂ in the butadiene block.

Further, the following chemical formula 4 shows an example in which the resin acid R ₁ is added in other blocks without being added in the block A ₁ in the butadiene block.

Thus, it is not essential that the resin acid R ₁ is added to the carbon constituting the blocks A ₁ and A ₂ in the butadiene block, and any resin other than the blocks A ₁ and A ₂ may be added. Good.

  The present invention may also be an asphalt composition containing the composition having the structure described above, with the balance being asphalt.

  At this time, as a ratio of these components, a styrene-butadiene-styrene copolymer (SBS) is less than 2 to 8% by weight and a polycyclic diterpene (resin acid) having 20 to 20 carbon atoms having a carboxyl group is 0.3 to 3% by weight may be contained, and the balance may be made of asphalt. The asphalt here is only one element constituting the asphalt composition which is the final product, and the asphalt composition is produced only by adding SBS and resin acid thereto.

  Asphalt is straight asphalt obtained as a residue obtained by distilling crude oil under reduced pressure, propane deasphalted asphalt obtained by removing crude oil under reduced pressure distillation residue with propane or the like, or crude oil vacuum distillation residue is removed with propane or the like. It is comprised with the extract etc. which were obtained by carrying out solvent extraction of the solvent de-peeling oil obtained by this. Instead of this extract, you may make it comprise aroma system oil. This aroma-based oil is specified in JISK6200 and is a hydrocarbon-based process oil containing at least 35% by mass of aromatic hydrocarbons.

  Asphalt is produced by any of the above-described vacuum distillation method, blowing (air blowing method), and blending method. That is, this asphalt includes at least one of propane-deasphalted asphalt, straight asphalt, and extract.

  The propane deasphalted asphalt is a so-called solvent deasphalted asphalt obtained by using a propane or a mixture of propane and butane as a solvent for the vacuum distillation residual oil. In addition to this propane deasphalted asphalt, any asphalt such as straight asphalt or blown asphalt may be used.

This propane deasphalting asphalt, for example, has a penetration of 8 (1/10 mm) at 25 ° C under JISK2207, a softening point of 66.5 ° C, and a density of 1028 kg / m ³ at 15 ° C You may make it do.

Further, as straight asphalt, for example, a material having a penetration of 65 (1/10 mm) at 25 ° C., a softening point of 48.5 ° C., and a density of 1034 kg / m ³ at 15 ° C. should be used. May be.

Extracts are extracted oils used to obtain heavy lubricating oil as refined oil by further solvent extraction of the solvent-depleted oil obtained by removing the vacuum distillation residue of crude oil with propane, etc. It is. Extract is as kinematic viscosity at 100 ° C. has a kinematic viscosity at 61.2mm ² / s, 40 ℃ density at 3970mm ² / s, 15 ℃ uses something like is 976.4kg / ^{m 3} Also good. Incidentally, the content of this extract is desirably 5% by weight or less based on the weight of the entire asphalt composition. The reason is that if the extract content exceeds 5% by weight, the strength of the obtained asphalt composition cannot be improved to a sufficient level in consideration of application as asphalt.

  Further, when the SBS content per total weight of the asphalt composition is less than 2% by weight in constituting the above-described asphalt composition, the degree of improvement in temperature sensitivity and physical strength by adding SBS is practically sufficient. In addition, the temperature dependence of the physical properties and properties of asphalt cannot be improved, and it becomes difficult to obtain appropriate physical properties and properties over a wide temperature range. On the other hand, when the SBS content is 8% by weight or more, the viscosity of the finally obtained asphalt composition becomes too large, and the workability when actually laying it on the road is remarkably deteriorated. It also becomes. On the other hand, when the SBS content is 8% by weight or more, the thermal stability and storage stability of the finally obtained asphalt composition are deteriorated, and a uniform composition cannot be obtained. For this reason, content of SBS shall be less than 2 to 8 weight%.

  Further, in constituting the asphalt composition, the above-mentioned polycyclic diterpene having 20 carboxyl groups (resin acid) contains 0.3 to 3% by weight based on the total weight of the asphalt composition. To do.

  If the content of the resin acid is less than 0.3% by weight, a polycyclic diterpene having 20 carbon atoms having a carboxyl group with respect to the butadiene block in SBS (abietic acid, dehydroabietic acid, neoabietic acid, pimaric acid, isopimar) Addition of acid, parastolic acid, etc.) is not sufficient, and the stability of the asphalt composition as the final product cannot be improved. On the other hand, if the content of the resin acid exceeds 3% by weight, not only the effect of improving the stability is saturated, but also the raw material cost due to an increase in the amount of expensive resin acid added. There arises a problem that the rise of the temperature becomes significant. That is, even if the resin acid content exceeds 3% by weight, the stability is not significantly improved, but it is disadvantageous in terms of raw material costs.

  Moreover, it is desirable that the C20 polycyclic diterpene (resin acid) having a carboxyl group is contained in a range of 0.3 to 1% by weight with respect to the total weight of the asphalt composition.

  By setting the upper limit of the content of the resin acid to 1% by weight, it is possible to improve the stability of the asphalt composition while suppressing an increase in raw material cost as much as possible, and to improve cost effectiveness. it can.

  In addition, when actually manufacturing the asphalt composition which consists of an above-described structure, the above-mentioned asphalt is prepared first. This asphalt is a mixture of one or more of straight asphalt, propane-deasphalted asphalt, and extract. While maintaining this asphalt at a temperature of about 195 ° C., 2 to less than 8% by weight of SBS is added, and 0.3 to 3% by weight of the resin acid described above is further added. Mix and stir for about 2 to 3 hours at 210 ° C. and a rotational speed of 1500 to 6000 rpm.

  Incidentally, the mixing time may depart from the range of 2 to 3 hours, but the mixing temperature needs to be in the range of 190 to 210 ° C. described above.

  When the mixing temperature is lower than 190 ° C., it becomes difficult to add a polycyclic diterpene having 20 carboxyl groups (resin acid) having a carboxyl group to the double bond constituting the butadiene block in SBS. The stability of SBS, that is, the tendency to separate and not float, the performance cannot be improved, and asphalt and SBS are separated as a result.

  Further, when the mixing temperature is 210 ° C. or higher, SBS itself is decomposed and deteriorated, and by adding and mixing SBS to asphalt, an improvement in strength and a decrease in temperature sensitivity (that is, temperature sensitivity) Improvement) cannot be achieved. For this reason, the mixing temperature is limited to the above-described range.

  As a result, the resin acid can be subjected to an addition reaction with the double bond constituting the butadiene block.

Further, the following chemical formula 5 shows an example in which isopimaric acid undergoes an addition reaction at the carbon C ₂ of the block A ₁ in the butadiene block as the resin acid R ₁ .

Since the oxygen atom in the carboxylic acid that actually constitutes isopimaric acid is negative, the hydrogen atom in the carboxylic acid is positive. Further, since the styrene block has an electron donating property, the double bond near the styrene block has a high electron density, and the styrene block itself is negatively charged as a whole. As a result, when isopimaric acid actually attacks the butadiene block, the hydrogen atoms in the positively charged carboxylic acid are attracted to the styrene block, resulting in the double bond of block A ₁ closest to the styrene block. Try to attack. Then, an electrophilic addition reaction occurs between the negatively charged hydrogen atom and the double bond.

As a result of this electrophilic addition reaction, isopimaric acid is added to carbon C ₂ of block A ₁ as shown in chemical formula 6 below.

In some cases, isopimaric acid is added to carbon C ₃ instead of carbon C ₂ in block A ₁ . Further, isopimaric acid is added to the block A _{2 by} the same mechanism.

Of course, isopimaric acid may be added not only to the blocks A ₁ and A ₂ but also to other double bonds of the butadiene block. The number of isopimaric acids added to the butadiene block may be any number. In addition to isopimaric acid, the above resin acids all have a carboxyl group and are composed of polycyclic diterpenes having 20 carbon atoms. As a result, it becomes possible to add a resin acid to a carbon atom.

  Among these resin acids, especially abietic acid and isopimaric acid increase the electron density of oxygen atoms in the carboxyl group, especially due to the bonding and electronic state of atoms in the molecule, resulting in a reaction with double bonds in the butadiene block. It becomes easy to do. For this reason, it is desirable to use especially abietic acid or isopimaric acid as the resin acid mentioned above.

  As a result, it is finally possible to obtain a styrene-butadiene composition as shown in Chemical Formula 1.

Thus, as described above, the resin acid R ₁ is added to the double bond of the butadiene blocks A ₁ and A ₂ closest to the styrene block in the styrene-butadiene composition to which the present invention is applied. The resin acid R _1, compared to the size of the styrene constituting the styrene block has a 2 to 3 times the size. As a result, this resin acid R ₁ has a function of inhibiting the free movement (separation) of SBS. When the bulky resin acid R ₁ is in the vicinity of the styrene block, it is possible to prevent the styrene blocks in the SBS added to the asphalt from aggregating with each other. By dispersing the styrene blocks without agglomeration, the SBS can be uniformly mixed with the asphalt, and the stability of the resulting asphalt composition itself can be improved.

  Examples of styrene-butadiene compositions to which the present invention is applied will be described in detail below.

  First, resin acid was added to SBS, and the reactivity was confirmed.

  As an example of the present invention, SBS is 4.5 in a state where it is maintained at a temperature of about 195 ° C. with respect to asphalt including any one or more of straight asphalt, propane deasphalted asphalt (PDA), and extract. An asphalt composition was prepared by adding 0.75% by weight of gum rosin as a resin acid.

  As a comparative example, 4.5% by weight of SBS was added to the same asphalt as in the example of the present invention at a temperature of about 195 ° C., and an asphalt composition in which no resin acid was intentionally added as in the example of the present invention was obtained. .

  Incidentally, SBS has a bromine number of 220 (g / 100 g: JIS K0070), a molecular weight of about 150,000, a styrene content of 32% by weight, and the amount of styrene block copolymer present at both ends of the elastomer molecule. A styrene-butadiene-styrene block copolymer having a weight ratio of 16% by weight was used.

  As the gum rosin, an acid value of 160 mgKOH / g was used.

In the experiment, the relationship between the elastic modulus and the loading time was investigated for the inventive example and the comparative example using a dynamic viscoelasticity tester. Specifically, as shown in FIG. 1, an asphalt binder 1 is sandwiched between two parallel disks 2 a and 2 b, a sine wave distortion of a predetermined frequency is applied to one disk 2 a, and the other is passed through the asphalt binder 1. The sinusoidal stress σ transmitted to the disk 2b is measured. The measurement conditions at that time are that the diameters of the disks 2a and 2b are 25 mm, the thickness of the asphalt binder 1 is 1 mm, and the strain is 10%. And based on the measurement result, complex elastic modulus G ^* is calculated | required from following Numerical formula (1). Here, γ in the following formula (1) is the maximum strain applied to the disk.

  The loss tangent (tan δ) is an index indicating the amount of energy lost in the asphalt composition when the sinusoidal distortion γ is added to the asphalt composition.

  A large loss tangent (tan δ) means that energy loss is large when strain is applied, that is, it is easily deformed, and when the applied strain is removed, it does not return to its original shape. In addition, a small loss tangent (tan δ) means a physical property in which energy loss is small when strain is applied, that is, deformation is difficult, and when the applied strain is removed, the original shape is desired to return.

The loss tangent (tan δ) is a sine wave γ having a predetermined angular frequency applied to one disk and the sine transmitted to the other disk via the asphalt composition when the above-described complex elastic modulus G ^* is measured. It is calculated from the phase difference δ with respect to the mechanical stress σ.

The above-mentioned complex elastic modulus G ^* and loss tangent (tan δ) may be measured based on the method “A062 Dynamic Shearometer Test Method” shown in the Pavement Survey and Test Method Handbook (edited by the Japan Road Association). .

FIG. 2 shows the complex elastic modulus G ^* and loss tangent (tan δ) at 60 ° C. of the present invention and the comparative example. From this, it was found that the complex elastic modulus G ^{* of} the present invention example is low when the loading time is long compared to the comparative example, in other words, when the angular frequency shown on the horizontal axis in FIG. 2 is small. It was also found that the loss tangent (tan δ) when the loading time is long is large and easily deformed, that is, when the applied strain is removed, it remains difficult to return to its original shape.

Further, it was found that the comparative example had a higher complex elastic modulus G ^* when the loading time was longer than that of the present invention. It was also found that the loss tangent (tan δ) when the loading time was long was small and difficult to deform, that is, it was easy to return to the original shape when the applied strain was removed.

  Furthermore, the relationship between the elastic modulus and the loading time of the asphalt composition to which the present invention was applied was investigated by measuring the softening point measured based on the method shown in JIS K2207.

  In the softening point test method shown in JIS K2207, a specified asphalt plate on which a ball of a specified weight is placed is placed in a water bath, and the temperature of the water bath is increased at a rate of 5 ° C./1 minute. The temperature at which a certain amount of deflection is generated is determined by the weight of the water and the bath temperature. That is, this softening point test is a test for measuring the ease of bending and deformation of asphalt when the loading time is long. As a result, the softening point of the inventive example was 60.0 ° C., whereas the comparative example was 79.0 ° C.

In these examples of the present invention, the meaning of a decrease in complex elastic modulus G ^*, an increase in loss tangent (tan δ), and a decrease in softening point indicate that styrene blocks are dispersed without agglomeration. Don't be.

On the other hand, in the comparative example in which no resin acid is added, it is considered that the styrene blocks are aggregated, and an aggregated structure of styrene blocks as shown in FIG. 6 is formed in the asphalt composition. At a long time, elasticity due to the styrene block and rubber elasticity due to the butadiene chain are remarkably exhibited, and an increase in the complex elastic modulus G ^* and a small loss tangent (tan δ) are observed.

  When the styrene blocks are aggregated as shown in FIG. 6 in the asphalt composition, the softening point becomes high. This is the same as when the glass transition point (Tg) of polystyrene, that is, the temperature at which polystyrene can freely move is 90 to 100 ° C., and the styrene block aggregates to increase the glass transition point Tg. This is because an effect is produced.

From the measurement results of the complex elastic modulus G ^* , loss tangent (tan δ), and softening point, in the asphalt composition to which the present invention is applied, the resin acid undergoes addition reaction with SBS, and the bulky resin near the styrene block. It can be seen that the addition of the acid molecules prevents the styrene blocks from aggregating with each other and disperses SBS well in the asphalt composition.

  Next, in order to confirm the reaction between SBS and resin acid, an infrared absorption analysis (IR) was actually performed. Two types of samples were prepared: abietic acid as a resin acid and a styrene-butadiene composition in which abietic acid was added to SBS. And about each, infrared absorption analysis was performed.

  Specifically, abietic acid and SBS are mixed with an oily substance produced by using the Fischer-Tropsch method, the mixing temperature is 195 ° C., and the number of rotations is 3500 rpm with a homomixer for about 3 hours. Stir. The production amount was 300 g.

  For comparison, SIS, SEBS and abietic acid were similarly mixed with an oily substance instead of SBS, and IR was measured.

  Incidentally, SBS has a bromine number of 220 (g / 100 g: JIS K0070), a molecular weight of about 150,000, a styrene content of 32% by weight, and the amount of styrene block copolymer present at both ends of the elastomer molecule. Styrene-butadiene-styrene block copolymers, each 16% by weight, were used.

  As the SIS, styrene having a bromine number of 220, a molecular weight of 220,000, a styrene content of 15% by mass, and the amount of styrene block copolymers present at both ends of the elastomer molecule is 7.5% by mass, respectively. An isoprene-styrene block copolymer (SIS) was used.

  SEBS has a bromine number of 5 (g / 100 g: JIS K0070), a molecular weight of 150,000, a styrene content of 30% by mass, and an amount of styrene block copolymer present at both ends of the elastomer molecule of 15%. % Styrene-ethylene-butylene-styrene block copolymer (SEBS) was used.

As the oily substance, one having a kinematic viscosity at 100 ° C. of 5.2 mm ² / s was used.

  FIG. 3 shows an IR spectrum of only abietic acid, and FIG. 4 shows an IR spectrum of a styrene-butadiene composition.

From the result of FIG. 3, it can be seen that a peak appears in the vicinity of 1690 cm ⁻¹ . This corresponds to the C═O bond of the carboxyl group in abietic acid.

Further, from the result of FIG. 4, it can be seen that a peak appears in the vicinity of 1740 cm ⁻¹ and a peak also appears in the vicinity of 1690 cm ⁻¹ . This peak near 1690 cm ⁻¹ is based on the C═O bond of the carboxyl group in abietic acid, and the peak near 1740 cm ⁻¹ is based on the ester. Incidentally, when an ester that is COOR (R is an arbitrary hydrocarbon molecule other than hydrogen) is produced, a characteristic peak is generated in the vicinity of 1740 cm ⁻¹ even if the C═O bond is the same.

  Therefore, it can be seen that by mixing SBS and abietic acid, an ester called COOR (R is an arbitrary hydrocarbon molecule other than hydrogen) is produced. It is conceivable that R here corresponds to SBS. For this reason, it is confirmed from this IR result that abietic acid reacts with SBS to form an ester. And as a place where this abietic acid reacts with SBS, the double bond in a butadiene block has the highest possibility from the viewpoint of the electron density mentioned above. For this reason, it turns out that the resin acid was added to the double bond of the butadiene block in a styrene-butadiene-styrene copolymer (SBS).

Only abietic acid and an oily substance were similarly stirred and mixed, and IR was measured. As a result, a peak around 1740 cm ⁻¹ due to the ester could not be confirmed.

For comparison, SIS, SEBS and abietic acid were mixed in place of SBS, and IR was measured. As a result, no peak in the vicinity of 1740 cm ⁻¹ corresponding to the ester was observed.

  From the above results, it can be seen that resin acid is added to the double bond of the butadiene block that exists only in SBS.

  From the above results, in SIS and SEBS, it was not possible to confirm a reaction to form an ester with a resin acid (in this case, abietic acid was used as an example). It was confirmed that an ester was formed between

  The reason why SEBS did not react with the resin acid is considered that SEBS has a styrene block, but butadiene does not exist and double bonds do not exist. Resin acids cannot cause an electrophilic addition reaction with SEBS having no double bond. On the other hand, in the styrene-butadiene composition to which the present invention is applied, it is premised that a resin acid is added to SBS. Since this butadiene block has a double bond, naturally, the butadiene block has a resin. It is conceivable that an acid is added.

  Moreover, although SIS had a double bond similarly to SBS, reaction with a resin acid was not able to be confirmed. Unlike SBS, SIS has a methyl group around the double bond. This is because when the resin acid tries to attack the double bond in the isoprene block, the presence of the methyl group becomes a steric hindrance, and bulky molecules such as resin acid are difficult to add to the double bond of the isoprene block. it is conceivable that.

  From the above experimental results, it is understood that the styrene / butadiene copolymer to be reacted with the resin acid is not SIS nor SEBS hydrogenated to the butadiene portion of SBS, and SBS must be selected. . In addition, it can be estimated that the resin acid is bonded by the addition reaction to the double bond of the butadiene block in SBS.

FIG. 5 shows the relationship between the complex elastic modulus G ^{* and the} loss tangent (tan δ) with respect to the angular frequency ω in the asphalt composition obtained by the present invention. A sinusoidal vibration was applied to the asphalt composition at a constant strain, the angular frequency ω was gradually increased, and the complex elastic modulus G ^{* and the} loss tangent (tan δ) were measured with respect to the angular frequency ω.

The complex elastic modulus G ^* defined in the present invention can be measured with a dynamic viscoelasticity tester. Specifically, as shown in FIG. 1, an asphalt binder 1 is sandwiched between two parallel disks 2 a and 2 b, a sine wave distortion of a predetermined frequency is applied to one disk 2 a, and the other is passed through the asphalt binder 1. The sinusoidal stress σ transmitted to the disk 2b is measured. The measurement conditions at that time are that the diameters of the disks 2a and 2b are 25 mm, the thickness of the asphalt binder 1 is 1 mm, and the strain is 10%. And based on the measurement result, complex elastic modulus G ^* is calculated | required from following Numerical formula (1). Here, γ in the following formula (1) is the maximum strain applied to the disk.

  The loss tangent (tan δ) is an index indicating the amount of energy lost in the asphalt composition when the sinusoidal distortion γ is added to the asphalt composition.

  A large loss tangent (tan δ) means that energy loss is large when strain is applied, that is, it is easily deformed, and when the applied strain is removed, it does not return to its original shape. In addition, a small loss tangent (tan δ) means a physical property in which energy loss is small when strain is applied, that is, deformation is difficult, and when the applied strain is removed, the original shape is desired to return.

The loss tangent (tan δ) is a sine wave γ having a predetermined angular frequency applied to one disk and the sine transmitted to the other disk via the asphalt composition when the above-described complex elastic modulus G ^* is measured. It is calculated from the phase difference δ with respect to the mechanical stress σ.

The above-mentioned complex elastic modulus G ^* and loss tangent (tan δ) may be measured based on the method “A062 Dynamic Shearometer Test Method” shown in the Pavement Survey and Test Method Handbook (edited by the Japan Road Association). .

Incidentally, in the example of FIG. 5, when 10% sine wave distortion was applied at 60 ° C. to an asphalt composition containing 4.5% by weight of SBS and 0.75% by weight of gum rosin and the balance being asphalt. The complex elastic modulus G ^* and the loss tangent (tan δ) are shown. Moreover, the mixing temperature at the time of preparing an asphalt composition is used as a sample which is varied to 180 ° C., 185 ° C., and 190 ° C., respectively.

  Especially when laying asphalt composition on the road with aggregates (crushed stone, sand, etc.) on the road pavement site, the pavement surface is flattened by heavy machinery (rollers, etc.) and human power, and the ride comfort during traffic driving Therefore, it is necessary to prevent the stumbling during walking and the prevention of water pool formation. In order to flatten the pavement surface, a large force is slowly applied to the pavement surface, and so-called ironing is performed.

  At this time, since the asphalt composition receives vibration at a low angular frequency ω, the higher the tan δ under the low angular frequency ω, the easier the asphalt composition is deformed and the less the restoring force, and the ease of installation in the field. That is, it is suitable for easily forming a flat road.

  The sample with a mixing temperature of 190 ° C. showed a tendency for tan δ at a low angular frequency ω to be higher than the other samples. On the other hand, when the mixing temperature was 185 ° C. or lower, there was a tendency for tan δ to decrease at the low angular frequency ω. For this reason, it turns out that it is desirable to make mixing temperature into 190 degreeC or more also from the point of workability.

Further, it is desirable that the complex elastic modulus G ^* is also small in the low angular frequency ω band. In particular, when compacting and flattening the asphalt composition, a load is applied to the asphalt composition at a low angular frequency ω band. In this case, the softer as much as possible, in other words, the lower the modulus of elasticity, Will be improved. Even when viewed from the viewpoint of the complex elastic modulus, the sample having a mixing temperature of 190 ° C. has a tendency to have a lower complex elastic modulus G ^{* at} a low angular frequency ω than the other samples. On the other hand, when the mixing temperature is 185 ° C. or lower, the complex elastic modulus G ^* at the low angular frequency ω is increased, and the workability tends to be deteriorated. For this reason, it turns out that it is desirable that mixing temperature shall be 190 degreeC or more from the point of workability.

  The asphalt composition produced by the manufacturing method as described above can be finished in a state where the asphalt and SBS are stabilized together without being separated. The reason is that the styrene blocks constituting the SBS have the property of aggregating with each other with the styrene blocks of the other SBS, but in the present invention, the styrene block having 20 carbon atoms having a carboxyl group in the double bond constituting the butadiene block Polycyclic diterpenes (resin acids) can be added. This is because, in particular, by adding a resin acid in the vicinity of the styrene block, a bulky resin acid acts on the styrene block, and as a result, aggregation of the styrene block can be solved. By releasing the aggregation of the styrene block, it is possible to ensure sufficient stability without separating SBS from asphalt.

  Incidentally, whether or not this asphalt composition is stable can be identified through storage stability. This storage stability is achieved by injecting an asphalt composition (about 250 g) 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, sealing, and heating at 170 ° C. for 48 hours. . Then, it can confirm by measuring the softening point in the upper 4 cm and the lower 4 cm of the asphalt composition injected into the aluminum cylindrical can. The measurement of the softening point may be based on the method shown in JISK2207. Then, the stability is determined through the absolute difference value of the difference between the upper softening point and the lower softening point. When the absolute value of the softening point difference is 3.0 ° C. or less, the asphalt composition can suppress the softening point difference to 3.0 ° C. or less when the storage stability is good. It becomes.

  Moreover, the strength of the asphalt composition produced through the manufacturing method as described above can be improved. The strength of this asphalt composition is determined from the DS value based on a wheel tracking test described in the Pavement Evaluation / Test Method Handbook (edited by the Japan Road Association). This DS value can be obtained from the following formula (2), and is the number of tire runnings between 45 minutes and 60 minutes with respect to the deformation amount (mm) of the asphalt composition between 45 minutes and 60 minutes. It can be obtained. The higher the DS value, the smaller the amount of deformation of the asphalt composition itself, which means that the material is more resistant to digging and has a higher strength.

・・・・・・・・・（２）

(2)

  In the asphalt composition, since the extract is particularly suppressed to 5% by weight or less, the above-mentioned DS value is approximately 6000 (times) in a dense mixture (aggregate maximum particle size 13 mm) used for general road pavement. / Mm) or more. By the way, if the DS value is 6000 (times / mm) or more, it is mentioned in the Handbook of Pavement Evaluation / Test Methods (Edited by the Japan Road Association) that there will be almost no problem in terms of strength as an asphalt composition. Yes.

  For this reason, according to the present invention, both improvement in storage stability by setting the softening point difference to 3.0 ° C. or less and improvement in strength by making the DS value 6000 (times / mm) or more are realized simultaneously. It becomes possible to do.

  The asphalt composition is premised on the case where it is applied to road pavement, but is not limited to this, and can of course be applied to waterproofing materials, adhesives, and the like.

  Examples of the present invention will be described in detail below. As shown in Table 1, with respect to asphalt containing any one or more of straight asphalt, propane deasphalted asphalt (PDA), and extract, SBS is maintained at a temperature of about 195 ° C. 5% by weight was added.

  As SBS, the bromine number is 220 (g / 100 g: JIS K0070), the molecular weight is about 150,000, the styrene content is 32% by mass, and the amount of the block copolymer of styrene present at both ends of the elastomer molecule is 16 A styrene-butadiene-styrene block copolymer having a mass% was used.

  And the asphalt composition shown in Comparative Examples 1 to 6 in which acid A (straight chain) was mixed with these, Examples 1 to 5 in which rosin B was mixed, Example 6 in which rosin C was mixed, An asphalt composition consisting of Example 7 mixed with abietic acid and Example 8 mixed with dehydroabietic acid was produced. In addition, in each asphalt composition of these Examples and Comparative Examples, the blending ratio of straight asphalt, propane deasphalting asphalt (PDA), and extract is prepared so that the penetration is 40-50.

  The acid A here is an acid value of 190 (mg KOH / g: JIS K0070), an iodine value of 110 (g / 100 g: JIS K0070), a linear 18-carbon monomer acid 7% by weight, and a 36-carbon dimer. It is a mixture of 76% by weight acid and 7% by weight trimer acid having 54 carbon atoms, and has an average molecular weight of about 590. Rosin B is 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). Rosin C is tall oil rosin having an acid value of 170 (mg KOH / g: JIS K0070), a saponification value of 178 (mg KOH / g: JIS K0070), and a softening point of 77.0 ° C. (JIS K2207).

  In the component stage in Table 1, all the numerical values in the table indicate wt%.

  Comparative Example 1 is an extract containing 12% by weight of asphalt, Comparative Example 2 is an extract containing 8% by weight of asphalt, and Comparative Example 3 is an extract of asphalt. In Comparative Examples 4 to 6, the extract in the asphalt was 4% by weight. In each of Comparative Examples 1 to 4, acid A (straight chain) was 0.3% by weight, Comparative Example 5 was acid A (straight chain) 0% by weight, and Comparative Example 6 was acid A (straight chain). Is mixed with 0.5% by weight. Moreover, Examples 1-5 add rosin B instead of the acid A (straight chain) which should be mixed in Comparative Examples 1-6. In Examples 1 to 5, the contents of rosin B are different from each other. Example 6 is a mixture of 0.75% by weight of rosin C, Example 7 is a mixture of 0.75% by weight of abietic acid, and Example 8 is a mixture of 0.75% by weight of dehydroabietic acid.

  As production conditions, in any composition, the mixing temperature was 195 ° C., and the mixture was stirred and stirred for about 2 hours at a rotation speed of 3500 rpm with a homomixer. The production amount was 1.8 kg in all cases.

  Table 1 also shows the results of measuring physical properties of each manufactured comparative example and each example. This physical property was measured with respect to penetration (1/10 mm), softening point (° C.), viscosity at 180 ° C. (mPa · s), storage stability, and DS value. The penetration is data at 25 ° C. measured under JISK2207. The softening point was also measured under the conditions of JIS K2207. The viscosity was measured under the conditions of JPI-5S-54-99 “Viscosity Test Method Using Asphalt-Rotational Viscometer” at a measurement temperature of 180 ° C., a spindle SC4-21, a spindle rotation speed of 20 revolutions / minute.

  The storage stability was as follows: an asphalt composition (about 250 g) 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, sealed, and heated at 170 ° C. 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. Table 1 shows the absolute value of the difference between the upper softening point and the upper and lower softening points, that is, the absolute difference of the softening points.

  The DS value was measured based on a wheel tracking test. This DS value is 30 cm in length, 30 cm in width, and 5 cm in thickness, which was prepared by using each asphalt composition and an aggregate containing the fine-grained asphalt mixture (13) and making the asphalt composition 5.6% by weight. A sheet-like specimen was used, and the test was performed based on the method defined in the Pavement Evaluation / 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. Then, based on the above-described formula (2), the DS value was calculated from the deformation amount from the time point of 45 minutes to the time point of 60 minutes from the start of the test.

  In Table 1 described above, first, the tendency of Comparative Examples 1 to 4 shows that the DS value improves as the extract is reduced. However, as the extract is decreased, the difference absolute value between the upper softening point and the lower softening point tends to increase. In particular, in Comparative Example 4, the extract was reduced to 4% by weight. As a result, the DS value could be improved to 7875 (times / mm), while the absolute value of the difference in softening point was 19.9. It has been shown to worsen to ° C.

  Further, as shown in Comparative Examples 5 and 6, when the extract is reduced to 4% by weight, the storage stability cannot be improved even if the content of the acid A, that is, the carboxylic acid is increased or decreased. It means that.

  In Example 1, the extract content is set to 4% by weight and rosin B is contained in an amount of 0.3% by weight. However, the DS value can be improved to 7000 (times / mm) or more. It can be seen that the absolute value of the difference between the softening points can be made as small as possible, and both the strength and the storage stability can be improved. Similarly, in Examples 2 to 5, the DS value was 7000 (times / mm) by setting rosin B to 0.6 wt%, 0.75 wt%, 1 wt%, and 1.5 wt%, respectively. It can be seen that the absolute value of the difference between the softening points can be suppressed to 1.3 ° C. or less while maintaining the above, and both the strength and the storage stability can be improved. However, with respect to the storage stability, it was found that even if the amount of rosin B added was increased, the difference in absolute value of the softening point did not change much. Even if this rosin A is added over 3% by weight, the absolute value of the difference between the softening points is considered to be almost unchanged.

  In Example 6, the extract was reduced to 4% by weight, and then rosin C was added at 0.75% by weight. Similarly, both the DS value and the absolute value of the difference between the softening points were the same. It was good. Similarly, in Example 7 in which abietic acid alone was added as the resin acid and in Example 8 in which dehydroabietic acid was added alone as the resin acid, both the DS value and the absolute value of the difference between the softening points were good. From the results of Examples 6 to 8, even when the type of the resin acid is changed, the storage stability is improved while ensuring the DS value at a high level by adding abietic acid and dehydroabietic acid alone. Is possible.

  Thus, from the results of Table 1, in order to improve both the DS value and the absolute value of the difference between the softening points, the extract is made 5 wt% or less and the resin acid is 0.3 to 3 wt%. It is shown that it can be realized by adding in the range of.

  From the results in Table 1, it can be seen that the storage stability increases when the softening point after the completion of the preparation of the asphalt composition (after manufacture) is lowered if the blended amount of SBS is the same. This is because, in a system in which the same amount of the same thermoplastic elastomer is blended, the lower the softening point after the preparation of the asphalt composition is, the lower the number of carbon atoms having a carboxyl group at the double bond constituting the butadiene block in SBS. This is because polycyclic diterpene (resin acid) is added and the stability is considered to be improved.

  In addition, Table 2 shows the results of verification experiments on whether styrene-ethylene-butylene-styrene (SEBS) and styrene-isoprene-styrene (SIS) exhibit the intended effects of the present invention as an alternative to SBS. ing. In this verification experiment, the production conditions of the asphalt composition are the same as in the example of Table 1 described above. Moreover, SBS, SEBS, and SIS were all added in an amount of 4.3% by weight, and the penetration, softening point, and viscosity (mPa.s) at 150 ° C. or 180 ° C. were measured.

  In Table 2, samples R1 and R2 are both examples using SBS. Sample R1 is a case where no gum rosin is added, and is a comparative example having a configuration different from that of the present invention. On the other hand, sample R2 is an example in which gum rosin is added over 0.75% by weight, and corresponds to an example of the present invention. When the physical properties of the samples R1 and R2 are compared, the softening point in the sample R2 is significantly lower than that in the sample R1, and the stability due to the addition of gum rosin is improved. I understand that.

  In Table 2, gum rosin corresponds to rosin B referred to in Table 1 of Example 4, and tall rosin corresponds to rosin C referred to in Table 1 of Example 4.

  On the other hand, samples S1 and S2 are examples in which SEBS is applied as an alternative to SBS.

  SEBS is a single bond formed by adding hydrogen to the double bond in the butadiene block of SBS. The bromine number is 5 (g / 100 g: JIS K0070), the molecular weight is about 150,000, and the styrene content is 30% by mass. A styrene-ethylene-butylene-styrene block copolymer (SEBS) in which the amount of the styrene block copolymer present at both ends of the elastomer molecule was 15% by mass was used.

  Sample S1 is a case where gum rosin is not added, and sample S2 is an example where gum rosin is added over 1% by weight. When the physical properties of the samples S1 and S2 are compared, it is shown that the softening point is hardly changed between the samples S1 and S2, and the effect of improving the stability by adding gum rosin is not expressed.

  Samples P1 to P6 show examples in which SIS is added as an alternative to SBS.

  As the SIS, the bromine number is 220 (g / 100 g: JIS K0070), the molecular weight is about 220,000, the styrene content is 15% by mass, and the amount of the block copolymer of styrene present at both ends of the elastomer molecule is 7 A styrene-isoprene-styrene block copolymer (SIS) that was 0.5 mass% was used.

  P1 to P3 are examples in which gum rosin was added, but the softening point hardly changed irrespective of the amount of gum rosin added and whether or not it was added. P4 to P6 are examples in which tall rosin was added, but the softening point hardly changed regardless of the amount of tall rosin added and whether or not it was added. Therefore, this SIS shows that the effect of improving the stability by adding rosin is not expressed.

  That is, in the present invention, the effect of improving the stability is exhibited by adding SBS, and even if SEBS or SIS is applied as an alternative to SBS, the desired effect cannot be exhibited. I understand. A butadiene block is sandwiched between styrene blocks, and only SBS can improve its own stability by adding a resin acid to a double bond constituting this butadiene block. SEBS and SIS, This is because the resin acid cannot be added, and as a result, stability cannot be improved.

Claims (6)

A styrene-butadiene-based composition comprising a polycyclic diterpene having 20 carbon atoms having a carboxyl group subjected to an addition reaction with a double bond of a butadiene block in a styrene-butadiene-styrene copolymer (SBS). 2. The styrene-butadiene composition according to claim 1, wherein the carboxyl group-containing polycyclic diterpene having 20 carbon atoms is subjected to addition reaction with a double bond of the butadiene block closest to the styrene block. object. A styrene-butadiene-based composition, wherein a polycyclic diterpene having 20 carbon atoms having a carboxyl group is added to a butadiene block in a styrene-butadiene-styrene copolymer (SBS). 4. The styrene-butadiene composition according to claim 3, wherein the polycyclic diterpene having 20 carbon atoms having a carboxyl group is added to at least the second or third closest carbon to the styrene block. The carbon number 20 polycyclic diterpene having a carboxyl group is any one or more of abietic acid, dehydroabietic acid, neoabietic acid, pimaric acid, isopimaric acid, and parastrinic acid. The styrene-butadiene composition according to any one of 1 to 4. An asphalt composition comprising the styrene-butadiene composition according to any one of claims 1 to 5, wherein the balance is asphalt.

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