JP7783161B2 - Asphalt additives, asphalt mixtures, roofing materials, and pavements - Google Patents

Description

The present invention relates to asphalt additives, asphalt mixtures, roofing materials, and pavements.

Asphalt pavement is used to pave roads, sidewalks, and other surfaces. In asphalt pavement, the road surface is formed from an asphalt mixture in which aggregate is bound with asphalt. For example, Patent Document 1 describes an asphalt composition containing asphalt and an asphalt additive containing a specific compound or its salt. Patent Document 1 also describes an asphalt mixture containing this asphalt composition and aggregate.

International Publication No. 2016/121580

However, pavements obtained using the asphalt mixture of Patent Document 1 suffer from the problem of severe deterioration over time. Furthermore, roofing materials obtained using the asphalt composition of Patent Document 1 also suffer from the same problem.

The object of the present invention is to provide an asphalt additive that suppresses deterioration over time when used in pavements or roofing materials.

The asphalt additive of the present invention contains a base oil (A) having a kinematic viscosity at 40°C of 50 cSt or more and 500 cSt or less, and a neutral phosphite ester derivative represented by the following formula (B) as an additive.

In the above formula (B), R ^b21 to R ^b24 each independently represent an aliphatic hydrocarbon group having 10 to 16 carbon atoms, R ^b25 to R ^b28 each independently represent a linear or branched alkyl group having 1 to 6 carbon atoms, R ^b291 and R ^b292 each independently represent a hydrogen atom or a linear or branched alkyl group having 1 to 5 carbon atoms, and the total number of carbon atoms in R ^b291 and R ^b292 is 1 to 5.

The asphalt additive of the present invention reduces deterioration over time when used in pavement or roofing materials.

Modes (embodiments) for carrying out the present invention will be described in detail. The present invention is not limited to the contents described in the following embodiments. Furthermore, the components described below include those that would be easily imagined by a person skilled in the art and those that are substantially identical. Furthermore, the configurations described below can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications to the configuration can be made without departing from the spirit of the present invention.

[Asphalt additives]
The asphalt additive (composition) of the embodiment includes a base oil (A) and an additive.

The base oil (A) has a kinematic viscosity (JIS K 2283) at 40°C of 50 cSt or more and 500 cSt or less. The base oil (A) does not need to be hydrotreated. Specifically, a base oil conforming to the viscosity grade VG220 to VG460 specified in ISO 3448 is preferably used. The base oil (A) is preferably a paraffinic mineral oil. It is more preferable that the base oil (A) be a mineral oil classified as Group 2 or 3 in the base oil categories defined by the American Petroleum Institute (API). The base oil (A) may be prepared by mixing one or more types. Such a base oil (A) is highly compatible with asphalt and can also dissolve the additives described below.

The additive contains a neutral phosphite ester derivative represented by the following formula (B). The neutral phosphite ester derivatives may be used alone or in combination. Conventionally, pavements are exposed to sunlight. The ultraviolet rays contained in sunlight cause the asphalt constituting the pavement to autooxidize, resulting in deterioration over time. Specifically, the pavement hardens and cracks. In contrast, the inclusion of a neutral phosphite ester derivative in the pavement effectively prevents asphalt oxidation and reduces pavement deterioration over time. Specifically, the neutral phosphite ester derivative is trivalent and absorbs oxygen, which induces deterioration, to convert to a pentavalent phosphate ester. The pentavalent phosphate ester irreversibly prevents oxidative deterioration without releasing oxygen. This prevents asphalt deterioration. Thus, producing pavements using an asphalt additive containing a neutral phosphite ester derivative prevents autooxidation of asphalt (hydrocarbons), thereby extending the life of the pavement. Furthermore, it will help reduce the frequency of road repairs, thereby helping to reduce the amount of asphalt used, which is derived from crude oil.

In formula (B), R ^b21 to R ^b24 each independently represent an aliphatic hydrocarbon group having 10 to 16 carbon atoms.

The aliphatic hydrocarbon group having 10 to 16 carbon atoms may be a straight-chain, branched, or cyclic aliphatic hydrocarbon group, and may be a saturated or unsaturated aliphatic hydrocarbon group. Specific examples of the aliphatic hydrocarbon group having 10 to 16 carbon atoms that can be used include straight-chain alkyl groups such as decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, and hexadecyl (cetyl) groups.

R ^b25 to R ^b28 each independently represent a linear or branched alkyl group having 1 to 6 carbon atoms.

Examples of straight-chain or branched alkyl groups having 1 to 6 carbon atoms include methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, isopropyl, sec-butyl, isobutyl, t-butyl, isopentyl, t-pentyl, neopentyl, and isohexyl.

The neutral phosphite ester has specific substituents in R ^b25 to R ^b28 and therefore has excellent antioxidant properties.

In particular, when R ^b25 and R ^b27 are linear alkyl groups having 1 to 6 carbon atoms, preferably 1 to 3 carbon atoms, and R ^b26 and R ^b28 are branched alkyl groups having 3 to 6 carbon atoms, preferably 3 to 4 carbon atoms, the antioxidant performance is further improved.

R ^b291 and R ^b292 each independently represent a hydrogen atom or a linear or branched alkyl group having 1 to 5 carbon atoms.

Examples of straight-chain or branched alkyl groups having 1 to 5 carbon atoms include methyl, ethyl, n-propyl, n-butyl, n-pentyl, isopropyl, sec-butyl, isobutyl, t-butyl, isopentyl, t-pentyl, and neopentyl groups.

However, the total number of carbon atoms in R ^b291 and R ^b292 is 1 to 5. Therefore, for example, when R ^b291 is a hydrogen atom, R ^b292 is a linear or branched alkyl group having 1 to 5 carbon atoms, when R ^b291 is a methyl group, R ^b292 is a linear or branched alkyl group having 1 to 4 carbon atoms, and when R ^b291 is an ethyl group, R ^b292 is a linear or branched alkyl group having 2 to 3 carbon atoms.

From the viewpoint of antioxidant performance, it is more preferable that R ^b291 is a hydrogen atom and R ^b292 is a linear or branched alkyl group having 1 to 5 carbon atoms.

The additive preferably further contains at least one selected from 2,6-di-t-butylphenol derivatives and hindered amine compounds. The 2,6-di-t-butylphenol derivatives may be used alone or in combination with two or more. The hindered amine compounds may be used alone or in combination with two or more. The use of 2,6-di-t-butylphenol derivatives has a high ability to trap radicals, further suppressing asphalt deterioration. Furthermore, hindered amine compounds can also efficiently demonstrate antioxidant performance in outdoor pavements.

2,6-di-t-butylphenol derivatives are represented by the following formula (C):

In formula (C), R ^c1 is a linear or branched alkyl group having 1 to 12 carbon atoms. Examples of the linear or branched alkyl group having 1 to 12 carbon atoms include methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, t-butyl, isobutyl, n-pentyl, isopentyl, t-pentyl, neopentyl, hexyl, heptyl, isoheptyl, n-octyl, isooctyl, 2-ethylhexyl, nonyl, and decyl. When R c1 is an alkyl group as described above, the compatibility of the 2,6-di-t-butylphenol derivative is improved.

The hindered amine compound is represented by the following formula (D):

R ^d21 and R ^d22 each independently represent an aliphatic hydrocarbon group having 1 to 10 carbon atoms.

The aliphatic hydrocarbon group having 1 to 10 carbon atoms may be a linear, branched, or cyclic aliphatic hydrocarbon group, and may be a saturated or unsaturated aliphatic hydrocarbon group.

Specific examples of aliphatic hydrocarbon groups having 1 to 10 carbon atoms include linear or branched alkyl groups such as methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, heptyl, octyl, nonyl, decyl, isopropyl, sec-butyl, isobutyl, t-butyl, isopentyl, t-pentyl, neopentyl, isohexyl, and 2-ethylhexyl. Among these, linear or branched alkyl groups having 5 to 10 carbon atoms are more preferred from the standpoint of antioxidant performance.

R ^d23 represents a divalent aliphatic hydrocarbon group having 1 to 10 carbon atoms.

Divalent aliphatic hydrocarbon groups having 1 to 10 carbon atoms are preferably divalent linear or branched alkylene groups such as methylene, 1,2-ethylene, 1,3-propylene, 1,4-butylene, 1,5-pentylene, 1,6-hexylene, 1,7-heptylene, 1,8-octylene, 1,9-nonylene, 1,10-decylene, and 3-methyl-1,5-pentylene. Of these, divalent linear or branched alkylene groups having 5 to 10 carbon atoms are more preferred from the standpoint of antioxidant performance.

From the viewpoint of antioxidant performance, it is more preferable that the sum of the numbers of carbon atoms of R ^d21 , R ^d22 and R ^d23 be 16 to 30.

From the viewpoint of antioxidant performance, it is preferable to contain the neutral phosphite ester derivative in an amount of 0.1 parts by mass or more and 10 parts by mass or less per 100 parts by mass of base oil (A). Note that the above amount refers to the total amount when two or more types of base oil (A) are used, and the total amount when two or more types of neutral phosphite ester derivatives are used.

When a 2,6-di-t-butylphenol derivative is used, from the viewpoint of antioxidant performance, it is preferable to include the 2,6-di-t-butylphenol derivative in an amount of 0.1 to 10 parts by mass per 100 parts by mass of base oil (A). Furthermore, when a hindered amine compound is used, it is preferable to include the hindered amine compound in an amount of 0.1 to 5 parts by mass per 100 parts by mass of base oil (A) from the viewpoint of antioxidant performance. Note that the above amount refers to the total amount when two or more types of base oil (A) are used. Furthermore, when two or more types of 2,6-di-t-butylphenol derivatives are used, it refers to the total amount, and when two or more types of hindered amine compounds are used, it refers to the total amount.

The asphalt additive can be obtained by mixing base oil (A), a neutral phosphite ester derivative, and, if necessary, a 2,6-di-t-butylphenol derivative and a hindered amine compound.

[Asphalt mixture]
The asphalt mixture of the embodiment contains the asphalt additive, asphalt, and aggregate. The use of the asphalt mixture makes it possible to obtain a pavement with a long life.

Examples of asphalt include natural asphalts such as lake asphalt and Gilsonite, and petroleum asphalts such as straight asphalt, semi-blown asphalt, and blown asphalt. Furthermore, modified asphalt or recycled asphalt may be used. One type of asphalt may be used alone, or two or more types may be used in combination. Examples of aggregates include crushed stone, boulders, gravel, sand, slag, filler, recycled aggregate, and ceramics. One type of aggregate may be used alone, or two or more types may be used in combination.

The above-mentioned asphalt additives are preferably added in an amount of, for example, 0.1 to 15 parts by mass per 100 parts by mass of asphalt. If the amount is less than 0.1 parts by mass, it will be difficult to achieve the effect of suppressing asphalt deterioration. If the amount is more than 15 parts by mass, mixing may become difficult and the mixture may become uneven. It is preferable to use the aggregate and asphalt in amounts that will provide the necessary strength for the pavement.

Typically, aggregate and asphalt are heated and mixed in a plant. Here, asphalt additives are also mixed to produce an asphalt mixture. Specifically, (1) aggregate and asphalt may be premixed, and then the asphalt additives are added and mixed; (2) aggregate, asphalt, and asphalt additives may be mixed simultaneously; (3) aggregate and asphalt additives may be premixed, and then asphalt is added and mixed; or (4) asphalt and asphalt additives may be premixed, and then aggregate is added and mixed. Furthermore, for example, mixing is performed while heating at a temperature between 100°C and 300°C. Because the asphalt additive contains base oil (A), the asphalt additive can be uniformly mixed with the asphalt and aggregate.

The asphalt mixture may contain other components. There are no particular restrictions on the other components, and they are appropriately selected and mixed from among commonly used components.

[Pavement]
The pavement of the embodiment includes the asphalt mixture described above. The pavement of the embodiment is specifically used for road pavement. A method for manufacturing a pavement, i.e., a road pavement construction method, includes, for example, a step of applying the asphalt mixture described above to a road or the like to form a pavement (asphalt pavement layer). The pavement (asphalt pavement layer) is preferably the surface layer of a road. In this case, the pavement of the embodiment is exposed to ultraviolet rays contained in sunlight, but deterioration of the asphalt is suppressed because an asphalt additive containing a neutral phosphite ester derivative is used. This extends the life of the pavement. This reduces the frequency of road repairs, which also helps reduce the amount of asphalt obtained from crude oil.

[Roofing materials]
The roofing material of the embodiment includes the asphalt additive described above and asphalt. Specifically, the roofing material of the embodiment may be a composite layer having an asphalt layer containing the asphalt additive described above and asphalt. The roofing material of the embodiment is applied to, for example, rooftops and other locations exposed to rain for waterproofing. In this case, the roofing material of the embodiment is also exposed to ultraviolet rays contained in sunlight, but deterioration of the asphalt is suppressed because the asphalt additive containing a neutral phosphite ester derivative is used. This extends the life of the roofing material. This reduces the frequency of repairs, which also helps reduce the amount of asphalt obtained from crude oil used.

Based on the above, the present invention relates to the following.
[1] An asphalt additive comprising a base oil (A) having a kinematic viscosity at 40°C of 50 cSt or more and 500 cSt or less, and a neutral phosphite ester derivative represented by the following formula (B) as an additive. The asphalt additive suppresses deterioration over time when used in pavements or roofing materials.

(In the above formula (B), R ^b21 to R ^b24 each independently represent an aliphatic hydrocarbon group having 10 to 16 carbon atoms, R ^b25 to R ^b28 each independently represent a linear or branched alkyl group having 1 to 6 carbon atoms, R ^b291 and R ^b292 each independently represent a hydrogen atom or a linear or branched alkyl group having 1 to 5 carbon atoms, and the total number of carbon atoms in R ^b291 and R ^b292 is 1 to 5.)

[2] The asphalt additive described in [1], further comprising at least one selected from a 2,6-di-t-butylphenol derivative represented by the following formula (C) and a hindered amine compound represented by the following formula (D). The use of a 2,6-di-t-butylphenol derivative has a high ability to trap radicals, further suppressing asphalt deterioration. Furthermore, the hindered amine compound can also efficiently demonstrate antioxidant performance in outdoor pavements.

(In the above formula (C), R ^c1 is a linear or branched alkyl group having 1 to 12 carbon atoms.)

(In the above formula (D), R ^d21 and R ^d22 each independently represent an aliphatic hydrocarbon group having 1 to 10 carbon atoms, and R ^d23 represents a divalent aliphatic hydrocarbon group having 1 to 10 carbon atoms.)

[3] The asphalt additive according to [1] or [2], containing the neutral phosphite ester derivative in an amount of 0.1 parts by mass or more and 10 parts by mass or less per 100 parts by mass of the base oil (A). When the neutral phosphite ester derivative is contained in an amount within the above range, antioxidant performance can be further enhanced.

[4] The asphalt additive according to [2], containing the 2,6-di-t-butylphenol derivative in an amount of 0.1 parts by mass or more and 10 parts by mass or less per 100 parts by mass of the base oil (A).
[5] The asphalt additive according to [2], containing the hindered amine compound in an amount of 0.1 to 5 parts by mass per 100 parts by mass of the base oil (A). When the neutral phosphite derivative, 2,6-di-t-butylphenol derivative, or hindered amine compound is contained in an amount within the above range, the additive can exhibit better antioxidant performance.
[6] An asphalt mixture comprising the asphalt additive according to [1] or [2], asphalt, and aggregate. The use of the asphalt mixture provides a pavement with a long life.

[7] A roofing material comprising the asphalt additive described in [1] or [2] and asphalt.

[8] A pavement containing the asphalt mixture described in [6]. The pavement or roofing material is resistant to deterioration over time.

[Example]
The present invention will be explained in more detail below based on examples, but the present invention is not limited to these examples.
[Example 1-1]
As the base oil (A), a paraffinic mineral oil (kinematic viscosity at 40°C (JIS K 2283): 320 cSt, trade name: Super Oil N320, manufactured by JXTG Nippon Oil & Energy Corporation) was used, and as additives, a neutral phosphite derivative, i.e., 4,4'-butylidenebis(3-methyl-6-t-butylphenyl ditridecyl phosphite), a 2,6-di-t-butylphenol derivative, i.e., octyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoate (CAS 125643-61-0, trade name: Irganox (registered trademark) L135, manufactured by BASF Japan Ltd.), and a hindered amine compound, i.e., decanedioate bis(2,2,6,6-tetramethyl-1-(octyloxy)piperidin-4-yl) were used.
Here, 0.1 parts by mass of a neutral phosphite ester derivative, 0.1 parts by mass of a 2,6-di-t-butylphenol derivative, and 0.1 parts by mass of a hindered amine compound were mixed with 100 parts by mass of the base oil (A) to obtain an asphalt additive (1-1).
Asphalt additive (1-1) was mixed with a cold asphalt mixture (product name: DR Mix, manufactured by Maeda Road Co., Ltd.) to obtain an asphalt mixture (1-1). Next, the asphalt mixture (1-1) was spread evenly on an iron plate (10 cm square) and compacted to obtain a pavement (1-1). Five pavements (1-1) were produced.

[Example 1-2]
An asphalt additive (1-2) was obtained in the same manner as in Example 1-1, except that 5 parts by mass of a neutral phosphite ester derivative, 5 parts by mass of a 2,6-di-t-butylphenol derivative, and 2.5 parts by mass of a hindered amine compound were mixed with 100 parts by mass of the base oil (A).
In addition, asphalt mixture (1-2) and then pavement (1-2) were obtained in the same manner as in Example 1-1, except that asphalt additive (1-2) was used instead of asphalt additive (1-1). Five pavements (1-2) were produced.

[Examples 1-3]
An asphalt additive (1-3) was obtained in the same manner as in Example 1-1, except that 10 parts by mass of a neutral phosphite ester derivative, 10 parts by mass of a 2,6-di-t-butylphenol derivative, and 5 parts by mass of a hindered amine compound were mixed with 100 parts by mass of the base oil (A).
In addition, asphalt mixture (1-3) and then pavement (1-3) were obtained in the same manner as in Example 1-1, except that asphalt additive (1-3) was used instead of asphalt additive (1-1). Five pavements (1-3) were produced.

[Example 2-1]
An asphalt additive (2-1) was obtained in the same manner as in Example 1-2, except that a paraffinic mineral oil (kinematic viscosity at 40 ° C. (JIS K 2283): 460 cSt, trade name: Super Oil N460, manufactured by JXTG Energy Corporation) was used instead of a paraffinic mineral oil (kinematic viscosity at 40 ° C. (JIS K 2283): 320 cSt, trade name: Super Oil N320, manufactured by JXTG Energy Corporation) as the base oil (A).
In addition, asphalt mixture (2-1) and then pavement (2-1) were obtained in the same manner as in Example 1-1, except that asphalt additive (2-1) was used instead of asphalt additive (1-1). Five pavements (2-1) were produced.

[Example 2-2]
An asphalt additive (2-2) was obtained in the same manner as in Example 1-2, except that a paraffinic mineral oil (kinematic viscosity at 40 ° C. (JIS K 2283): 430 cSt, trade name: Diana Fresia P430, manufactured by Idemitsu Kosan Co., Ltd.) was used instead of a paraffinic mineral oil (kinematic viscosity at 40 ° C. (JIS K 2283): 320 cSt, trade name: Super Oil N320, manufactured by JXTG Energy Corporation) as the base oil (A).
In addition, asphalt mixture (2-2) and then pavement (2-2) were obtained in the same manner as in Example 1-1, except that asphalt additive (2-2) was used instead of asphalt additive (1-1). Five pavements (2-2) were produced.

[Example 2-3]
An asphalt additive (2-3) was obtained in the same manner as in Example 1-2, except that naphthenic mineral oil (kinematic viscosity at 40 ° C. (JIS K 2283): 220 cSt, trade name: Kurisef Oil H220, manufactured by JXTG Energy Corporation) was used instead of paraffinic mineral oil (kinematic viscosity at 40 ° C. (JIS K 2283): 320 cSt, trade name: Super Oil N320, manufactured by JXTG Energy Corporation) as base oil (A).
In addition, asphalt mixture (2-3) and then pavement (2-3) were obtained in the same manner as in Example 1-1, except that asphalt additive (2-3) was used instead of asphalt additive (1-1). Five pavements (2-3) were produced.

[Example 2-4]
An asphalt additive (2-4) was obtained in the same manner as in Example 1-2, except that naphthenic mineral oil (kinematic viscosity at 40 ° C. (JIS K 2283): 220 cSt, trade name: SNH220, manufactured by Sankyo Yuka Kogyo Co., Ltd.) was used instead of paraffinic mineral oil (kinematic viscosity at 40 ° C. (JIS K 2283): 320 cSt, trade name: Super Oil N320, manufactured by JXTG Energy Corporation) as base oil (A).
In addition, asphalt mixture (2-4) and then pavement (2-4) were obtained in the same manner as in Example 1-1, except that asphalt additive (2-4) was used instead of asphalt additive (1-1). Five pavements (2-4) were produced.

[Examples 3-1 to 3-6]
Asphalt additives ( ^3-1) to ( ^3-6 ) were obtained in the same manner as in Example 1-2, except that the compounds in Table 1 were used instead of 4,4'-butylidenebis(3-methyl-6-t-butylphenyl ditridecyl phosphite) (in the above formula (B), R ^b21 to R ^b24 = tridecyl groups, R ^b25 and R ^b27 = methyl groups, R ^b26 and R ^{b28 = t-butyl groups, R b291} = hydrogen atom, and R b292 = n-propyl group) as the neutral phosphite ester derivative.
In addition, asphalt mixtures (3-1) to (3-6) were obtained in the same manner as in Example 1-1, except that asphalt additives (3-1) to (3-6) were used instead of asphalt additive (1-1). Five pavements (3-1) to (3-6) were produced for each of the samples.

[Examples 4-1 to 4-6]
Asphalt additives (4-1) to (4-6) were obtained in the same manner as in Example 1-2, except that the compounds in Table 2 were used instead of bis(2,2,6,6-tetramethyl-1-(octyloxy)piperidin-4-yl) decanedioate (in the above formula (D) R ^d21 , R ^d22 = n-octyl group, R ^d23 = 1,8-octylene group) as the hindered amine compound.
In addition, asphalt mixtures (4-1) to (4-6) were obtained in the same manner as in Example 1-1, except that asphalt additives (4-1) to (4-6) were used instead of asphalt additive (1-1). Five pavements (4-1) to (4-6) were produced for each.

[Example 5-1]
A paraffinic mineral oil (kinematic viscosity at 40°C (JIS K 2283): 320 cSt, trade name: Super Oil N320, manufactured by JXTG Nippon Oil & Energy Corporation) was used as the base oil (A), and a neutral phosphite derivative, i.e., 4,4'-butylidenebis(3-methyl-6-t-butylphenyl ditridecyl phosphite), was used as the additive.
Here, 100 parts by mass of the base oil (A) was mixed with 5 parts by mass of the neutral phosphite ester derivative to obtain an asphalt additive (5-1).
In addition, asphalt mixture (5-1) and then pavement (5-1) were obtained in the same manner as in Example 1-1, except that asphalt additive (5-1) was used instead of asphalt additive (1-1). Five pavements (5-1) were produced.

[Example 5-2]
As the base oil (A), a paraffinic mineral oil (kinematic viscosity at 40°C (JIS K 2283): 320 cSt, trade name: Super Oil N320, manufactured by JXTG Nippon Oil & Energy Corporation) was used, and as the additives, a neutral phosphite ester derivative, i.e., 4,4'-butylidenebis(3-methyl-6-t-butylphenyl ditridecyl phosphite) and a 2,6-di-t-butylphenol derivative, i.e., octyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoate (CAS 125643-61-0, trade name: Irganox (registered trademark) L135, manufactured by BASF Japan Ltd.) were used.
Here, 100 parts by mass of the base oil (A) was mixed with 5 parts by mass of the neutral phosphite ester derivative and 5 parts by mass of the 2,6-di-t-butylphenol derivative to obtain an asphalt additive (5-2).
In addition, asphalt mixture (5-2) and then pavement (5-2) were obtained in the same manner as in Example 1-1, except that asphalt additive (5-2) was used instead of asphalt additive (1-1). Five pavements (5-2) were produced.

[Example 5-3]
A paraffinic mineral oil (kinematic viscosity at 40°C (JIS K 2283): 320 cSt, trade name: Super Oil N320, manufactured by JXTG Nippon Oil & Energy Corporation) was used as the base oil (A), and a neutral phosphite derivative, i.e., 4,4'-butylidenebis(3-methyl-6-t-butylphenyl ditridecyl phosphite), and a hindered amine compound, i.e., decanedioate bis(2,2,6,6-tetramethyl-1-(octyloxy)piperidin-4-yl), were used as additives.
Here, 100 parts by mass of the base oil (A) was mixed with 5 parts by mass of the neutral phosphite ester derivative and 2.5 parts by mass of the hindered amine compound to obtain an asphalt additive (5-3).
In addition, asphalt mixture (5-3) and then pavement (5-3) were obtained in the same manner as in Example 1-1, except that asphalt additive (5-3) was used instead of asphalt additive (1-1). Five pavements (5-3) were produced.

[Comparative Example 1-1]
A cold asphalt mixture (product name: DR Mix, manufactured by Maeda Road Co., Ltd.) was mixed with a paraffinic mineral oil (kinematic viscosity at 40 ° C (JIS K 2283): 320 cSt, product name: Super Oil N320, manufactured by JXTG Energy Corporation) as base oil (A) to obtain an asphalt mixture (1-1'). The asphalt mixture (1-1') was spread evenly on an iron plate (10 cm square) and compacted to obtain a pavement (1-1'). Five pavements (1-1') were produced.

[Evaluation method and results]
Of the five pavement bodies (1-1) produced in Example 1-1, the first to fifth were used in the following heating tests 1 to 5, respectively. The following heating tests 1 to 5 were also carried out on the pavement bodies produced in the other examples and comparative examples.
(Heating test 1)
The prepared pavement was placed in an incubator and kept at 100°C for one month.
(Heating test 2)
The prepared pavement was placed in an incubator and kept at 100°C for 3 months.
(Heating test 3)
The prepared pavement was placed in an incubator and kept at 100°C for 6 months.
(Heating test 4)
The prepared pavement was placed in an incubator and kept at 100°C for one month under ultraviolet irradiation.
(Heating test 5)
The prepared pavement was placed in an incubator and kept at 100°C for 3 months under ultraviolet irradiation.
(Appearance observation)
For each pavement subjected to heating tests 1 to 5, the pavement was removed from the incubator, cooled to room temperature, and then its appearance was observed. Specifically, a score of ◯ was given if there was no change in the surface of the pavement and no cracks had occurred, and an X was given if cracks had occurred on the surface of the pavement. The test results are shown in Table 3.

In all examples, no cracks were observed by visual observation even after heating tests 1, 2, and 4 were performed. It can be seen that deterioration over time is suppressed in pavements using the asphalt additive of the embodiment. In examples using asphalt additives containing a neutral phosphite ester derivative, a 2,6-di-t-butylphenol derivative, and a hindered amine compound, no cracks were observed by visual observation even after heating tests 3 and 5 were performed. It can be seen that when a neutral phosphite ester derivative, a 2,6-di-t-butylphenol derivative, and a hindered amine compound are used in combination, deterioration over time is suppressed even when used outdoors for long periods of time.
Furthermore, from the above results, it can be seen that deterioration over time can also be suppressed for roofing materials using the asphalt additive of the embodiment.

Claims (8)

A base oil (A) having a kinematic viscosity at 40°C of 50 cSt or more and 500 cSt or less;
and a neutral phosphite ester derivative represented by the following formula (B) as an additive,
Asphalt additive.

(In the above formula (B), R ^b21 to R ^b24 each independently represent an aliphatic hydrocarbon group having 10 to 16 carbon atoms, R ^b25 to R ^b28 each independently represent a linear or branched alkyl group having 1 to 6 carbon atoms, R ^b291 and R ^b292 each independently represent a hydrogen atom or a linear or branched alkyl group having 1 to 5 carbon atoms, and the total number of carbon atoms in R ^b291 and R ^b292 is 1 to 5.) The additive further contains at least one selected from a 2,6-di-t-butylphenol derivative represented by the following formula (C) and a hindered amine compound represented by the following formula (D):
The asphalt additive according to claim 1.

(In the above formula (C), R ^c1 is a linear or branched alkyl group having 1 to 12 carbon atoms.)

(In the above formula (D), R ^d21 and R ^d22 each independently represent an aliphatic hydrocarbon group having 1 to 10 carbon atoms, and R ^d23 represents a divalent aliphatic hydrocarbon group having 1 to 10 carbon atoms.) The neutral phosphite ester derivative is contained in an amount of 0.1 parts by mass or more and 10 parts by mass or less relative to 100 parts by mass of the base oil (A).
The asphalt additive according to claim 1 or 2. The 2,6-di-t-butylphenol derivative is contained in an amount of 0.1 parts by mass or more and 10 parts by mass or less relative to 100 parts by mass of the base oil (A).
The asphalt additive according to claim 2. The hindered amine compound is contained in an amount of 0.1 parts by mass or more and 5 parts by mass or less relative to 100 parts by mass of the base oil (A).
The asphalt additive according to claim 2. An asphalt mixture comprising the asphalt additive according to claim 1 or 2, asphalt, and aggregate. A roofing material comprising the asphalt additive according to claim 1 or 2 and asphalt. A pavement comprising the asphalt mixture described in claim 6.