JP2018080212A - Workability improver for asphalt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a workability improver for asphalt that can be added to asphalt for softening it, thereby improving the workability; prevents a delay in its curing at a temperature where a road is opened; and does not cause a poor appearance such as whitening.SOLUTION: A workability improver for asphalt comprises an ester of a C18-22 monovalent unsaturated fatty acid and one or more alcohol selected from the group consisting of a C8-18 monovalent saturated branched alcohol and a C8-18 monovalent unsaturated linear alcohol.SELECTED DRAWING: None

Description

  The present invention relates to a workability improving agent for asphalt used for road pavement.

  The asphalt mixture in which asphalt and aggregate are mixed is heated to reduce the viscosity of the asphalt in order to improve the mixability and workability of the asphalt and aggregate during manufacture or construction. Usually, the road pavement construction temperature is as high as 120 to 140 ° C., and when it is heated for a long period of time, there is a possibility that the asphalt will gradually deteriorate. Therefore, in order to suppress the deterioration of asphalt, additives such as mineral oil are softened by adding asphalt to reduce the construction temperature. However, since mineral oil dissolves asphalt, the asphalt mixture produced by this method may have the work environment deteriorated due to adhesion or flow of dissolved asphalt.

  In order to solve this problem, a method of adding an additive for softening asphalt instead of dissolving asphalt has been studied. For example, it has been proposed to add polyolefin wax to asphalt (Patent Document 1, Patent Document 2).

  However, polyolefin wax tends to soften asphalt, and it may be difficult to harden even after the construction of the asphalt composite material even at a temperature at which the road is opened, and it may take time to cure properly after construction.

  As a softening agent for asphalt with improved time to cure, it has been proposed to add a fatty acid amide or a fatty acid metal salt to the asphalt (Patent Document 3).

JP 2006-22289 Special table 2012-500329 JP2009-212436

  However, although fatty acid amides harden at the temperature at which roads are opened, they are apt to bleed out and cause poor appearance such as whitening due to poor compatibility with asphalt.

  Therefore, there is a demand for a workability improving agent for asphalt that has an effect of softening asphalt, suppresses a decrease in curing at a temperature at which the road is opened, and does not cause appearance defects such as whitening.

  It is an object of the present invention to improve workability by adding to and soften asphalt, to suppress a decrease in curing at a temperature that opens a road, and to prevent appearance defects such as whitening, asphalt workability It is to provide an improving agent.

  That is, the present invention is a group consisting of a monovalent unsaturated fatty acid having 18 to 22 carbon atoms, a monovalent saturated branched alcohol having 8 to 18 carbon atoms, and a monovalent unsaturated linear alcohol having 8 to 18 carbon atoms. The present invention relates to a workability improving agent for asphalt characterized by comprising an ester with one or more selected alcohols.

  By using the asphalt workability improver of the present invention, while softening the asphalt and improving the workability in manufacturing, transportation, and construction work, it suppresses the decrease in hardening after construction of the produced asphalt mixture, whitening, etc. The appearance defect can be suppressed.

  The workability improving agent for asphalt of the present invention includes a monovalent unsaturated fatty acid having 18 to 22 carbon atoms, a monovalent saturated branched alcohol having 8 to 18 carbon atoms, and a monovalent unsaturated straight chain having 8 to 18 carbon atoms. It consists of ester with 1 or more types of alcohol chosen from the group which consists of chain alcohol.

  When the valence of a monovalent unsaturated fatty acid having 18 to 22 carbon atoms is 2 or more, the effect of softening asphalt is reduced, so the valence of the fatty acid is monovalent. Moreover, when the carbon number of the fatty acid is 17 or less, curing failure may occur at the time of construction, so the carbon number is 18 or more. Moreover, since the effect which softens asphalt will become low when carbon number of this fatty acid exceeds 22, carbon number shall be 22 or less.

  The carbon chain of the monovalent unsaturated fatty acid having 18 to 22 carbon atoms may be linear, branched, or a combination thereof. Moreover, although the number of the unsaturated bond which this fatty acid has is not limited, it is preferable that it is 1-3. Specific examples of the fatty acid include oleic acid, linoleic acid, linolenic acid, erucic acid and the like. Among these, oleic acid and erucic acid are preferable, and oleic acid is particularly preferable.

  The alcohol constituting the ester of the present invention is one or more alcohols selected from the group consisting of monovalent saturated branched alcohols having 8 to 18 carbon atoms and monovalent unsaturated linear alcohols having 8 to 18 carbon atoms. is there.

  When the alcohol has 7 or less carbon atoms, it may cause curing failure during construction, so the carbon number is 8 or more, but 10 or more is more preferable. In addition, when the alcohol has 19 or more carbon atoms, the effect of softening the asphalt is reduced, so the carbon number is 18 or less, and more preferably 14 or less.

  The alcohol is preferably a saturated branched alcohol having 8 to 18 carbon atoms, and more preferably a saturated branched alcohol having 10 to 14 carbon atoms.

  Specific examples of the alcohol include 2-ethylhexanol, isononanol, isodecyl alcohol, isododecyl alcohol, isotridecyl alcohol, isotetradecyl alcohol, isopentadecyl alcohol, isohexadecyl alcohol, isostearyl alcohol, and oleyl alcohol. As an example, isotridecyl alcohol having 13 carbon atoms is particularly preferable. Examples of commercially available products include tridecanol (manufactured by KH Neochem Co., Ltd.), EXXAL13 (manufactured by ExxonMobil), and MARLIPAL O13 (manufactured by Sasol).

  The workability improving agent for asphalt of the present invention can be used for new asphalt, can be used for regenerated asphalt, and can also be used for a mixture of new asphalt and regenerated asphalt. Specifically, examples of the new asphalt include straight asphalt, semi-blown asphalt, modified asphalt obtained by adding a polymer such as SBS as a modifier to petroleum asphalt, and high viscosity asphalt for drainage pavement. In addition, examples of recycled asphalt include recycled asphalt obtained by crushing and using old or damaged asphalt pavement.

  Moreover, although the addition amount of the workability improving agent for asphalt of this invention is not limited, It is preferable to add 0.1-3 mass parts of workability improving agents with respect to 100 mass parts of asphalt.

  The workability improver for asphalt of the present invention may be added at any stage as long as the asphalt is heated to have fluidity, but is usually added when producing the asphalt mixture. To do. Asphalt composites are generally produced by mixing aggregates composed of asphalt, crushed stone, gravel, stone powder, etc., workability improving agents for asphalt, and other additives as required.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples.
Table 1 shows the types of asphalt workability improvers used. Especially about an Example and Comparative Examples 1 and 2, the combination of the fatty acid and alcohol which comprise ester is shown. In addition, the comparative example 5 is a comparison object (blank) which has not added the workability improving agent. And it evaluated as follows using the workability improving agent of each case. The evaluation results are shown in Table 2.

(1) Evaluation of viscosity softening property was performed by measuring the viscosity of asphalt. The softening property was evaluated based on the viscosity by measuring the viscosity using a B-type viscometer (manufactured by Toki Sangyo Co., Ltd.). Specifically, about 40 g of straight asphalt 60/80 (manufactured by Showa Shell Sekiyu KK) is weighed into a 50 ml capacity glass bottle, and as shown in Table 2, the modifiers of each example shown in Table 1 are asphalt. Each sample was prepared by adding to 1 wt% and stirring. The viscosity of the prepared sample was measured at 90 ° C. and evaluated as follows.

A: Viscosity is 2500 mPa · s or less ○: Viscosity is greater than 2500 mPa · s ×: 4000 mPa · s or less X: Viscosity is greater than 4000 mPa · s

(2) Suppression of curing reduction The suppression of curing reduction was evaluated by measuring penetration. The penetration is EX-210ED DEGITAL
Measured using PENETROMETER (ELEX SCIENTIFIC CO., LTD). The measuring method was based on Japanese Industrial Standard (JIS K 2207: 1996 petroleum asphalt). That is, 40 g of straight asphalt 60/80 (manufactured by Showa Shell Sekiyu KK) was placed in a 50 ml aluminum cup, and 1 wt% of the additive was added to the straight asphalt 60/80, and the sample was heated and mixed at 100 ° C. It was prepared by cooling to 25 ° C. later. The length of 0.1 mm that the needle entered vertically into the sample was expressed as a penetration of 1, and the evaluation was performed as follows.

◎: Needle penetration is 90 or less ○: Needle penetration is 90 or more and less than 120 △: Needle penetration is 120 or more and less than 150 ×: Needle penetration is 150 or more

(3) Appearance was evaluated by confirming changes in appearance by visual inspection. Specifically, 40 g of straight asphalt 60/80 (manufactured by Showa Shell Sekiyu KK) was placed in a 50 ml glass container, and 1 wt% of the additive was added to the straight asphalt 60/80, and the mixture was heated and mixed at 100 ° C. After cooling to 25 ° C., the change in appearance was visually confirmed and evaluated as follows.

○: No change in appearance ×: Whitening and change in appearance

  In the asphalt workability improvers of Examples 1 to 5, a good asphalt softening effect and an effect of suppressing a decrease in curing were obtained.

In Comparative Example 1, the use of fatty acids having 17 or less carbon atoms caused a decrease in asphalt hardening.
In Comparative Example 2, since the number of carbon atoms was 7 or less and linear saturated alcohol was used, asphalt hardening decreased.
In Comparative Example 3, since light oil was used, the hardening decreased because the asphalt was dissolved.
In Comparative Example 4, since an amide compound was used, the blending with asphalt was poor and whitening occurred, resulting in a change in appearance.

Claims (1)

One or more selected from the group consisting of a monovalent unsaturated fatty acid having 18 to 22 carbon atoms, a monovalent saturated branched alcohol having 8 to 18 carbon atoms and a monovalent unsaturated linear alcohol having 8 to 18 carbon atoms A workability improving agent for asphalt, characterized by comprising an ester with an alcohol.