JPH0519586B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention improves the toughness and tenacity of asphalt by mixing it into heated and melted asphalt for road paving, and in particular significantly improves the crack prevention effect of road paving materials using the asphalt. This invention relates to additives for modified asphalt.

Prior Art and its Problems As a general rule, asphalt road paving materials are manufactured to meet or conform to the standards of the Asphalt Paving Guidelines established by the Japan Road Association, and are used for paving.

According to the Asphalt Paving Guidelines, asphalt road paving materials are usually made by putting pre-heated aggregate such as crushed stone or sand into a mixer, adding a filler at room temperature, dry kneading for 5 seconds or more, and then achieving a viscosity of 150. It is manufactured by injecting heated asphalt to ~300 centistokes and mixing for about 40-50 seconds until the asphalt coats all of the aggregate.

In addition, the asphalt content in asphalt road paving materials is approximately 4 to 20% by weight, including special uses.
It is generally considered to be about 4 to 9.5% by weight.

Conventional asphalt road paving materials have many drawbacks, and there is an urgent need to develop technology to improve them. The disadvantages are "ruts" caused by larger vehicles and a significant increase in traffic volume;
These problems include abrasion, cracking, flow, partial settlement, and other damage, and these problems cannot be sufficiently resolved with the conventional combination of aggregate, filler, and asphalt, even if the mixing ratio, compounding method, and construction method are improved. This can lead to traffic accidents, and shortening the lifespan of pavement is also an important issue from the perspective of resource conservation. In more special cases, flow due to high temperatures in summer, embrittlement in cold regions,
Damage caused by tires mounted on chains on roads in snow-covered areas, especially snow-clearing roads, roads inside tunnels, and roads inside shelters, remained a problem that needed to be solved.

As an effective method to solve these problems, attempts have been made for a long time to add rubber, plastic, etc. to asphalt, and this has achieved some success.

However, although modified asphalt road paving materials using rubber, plastic, etc. as the modifying material have been prevented from cracking, they have poor flow resistance and abrasion resistance, and have the disadvantage of being prone to "rutting". . Ethylene-ethyl acrylate copolymer powder, which has good flow resistance, is used as a modifier for asphalt to prevent "ruts" and has been highly effective as a modified asphalt road paving material.

However, modified asphalt road paving materials using ethylene-ethyl acrylate copolymer powder as an asphalt modifier have a problem of cracking because the modified asphalt lacks adhesiveness and caking properties.

On the other hand, there is a trend to establish standards for modified asphalt made from rubber or plastic. These criteria include toughness and tenacity, which indicate the adhesion and caking properties of modified asphalt. According to certain standards, the toughness is 30kg/cm or more, and the tenacity is 10kg/cm or more.
cm or more.

However, the toughness value of modified asphalt containing ethylene-ethyl acrylate copolymer powder, which is currently used as an asphalt modifying material, is 55 kg・cm and the tenacity value is approximately 10 kg・cm, which does not meet the standard values. However, as the times progress, asphalt road paving materials are expected to increase in traffic volume and increase in the number of heavy vehicles, so even higher quality will be required. is requested to develop.

That is, there is a demand for asphalt with further improved toughness and tenacity, and it has become essential to have crack-preventing properties.

OBJECTS OF THE INVENTION It is an object of the present invention to provide a modified asphalt additive that meets the above requirements.

DETAILED DESCRIPTION OF THE INVENTION The present invention comprises the following modified asphalt additives (1) and (2).

(1) An additive for modified asphalt characterized by being short fibers made of acid-modified ethylene-ethyl acrylate copolymer.

(2) Acid-modified ethylene-ethyl acrylate copolymer (hereinafter also referred to as acid-modified EEA) has a diameter
An additive for modified asphalt, characterized in that it is a granular material obtained by kneading and pulverizing 0.005 to 0.150 mm fibrous glass to obtain a particle size of 6 to 35 mesh.

The additive for modified asphalt of the present invention is a powder obtained by pulverizing short fibers made of a resin component or a kneaded product of a resin component and fibrous glass, and the modified asphalt obtained by adding these additives to asphalt has adhesive properties. and caking properties, that is, toughness and tenacity, are increased, and asphalt road paving materials using the modified asphalt have improved heat resistance, cold resistance, and anti-rutting properties, especially with the addition of ethylene-ethyl acrylate copolymer powder. Excellent effectiveness was observed in preventing cracks, which could not be solved previously.

Although not bound by any particular theory, in conventional methods, rubber, adhesive resin, etc. are added to improve toughness, tenacity, crack prevention, etc., and the problem is solved by increasing chemical bonding strength. However, in the present invention, acid-modified
Powder obtained by kneading EEA short fibers or acid-modified EEA with fibrous glass and pulverizing the powder (from a macroscopic perspective, this powder is resin-coated short fiber glass) is added, and the mixture is placed in modified asphalt. It is presumed that short resin fibers or short resin-coated glass fibers have a macroscopic wire structure, that is, a three-dimensional structure, or a structure close to it. The difference is that this is based on a new technical idea of improving the properties by increasing the strong chemical bonding force and physical bonding force of acid-modified EEA.

It is known that the ethylene-ethyl acrylate copolymer, which is the raw material for the acid-modified EEA used in the present invention, can be used in the form of a powder as a modifier for asphalt, but if it is used as an acid-modified product in the form of short fibers, The present invention is the first to achieve a revolutionary improvement in the properties of asphalt and road paving materials using the same, particularly in the crack prevention properties. The modified ethylene-ethyl acrylate copolymer used in the present invention has never been used as a modifier for asphalt, and is sufficiently effective even when used as a powder or granule. The effect is more pronounced when it is used by coating short fibers or short fiber glass.

In the present invention, the term aggregate refers to a mixture of crushed stone and sand that is commonly used for paving, but it also includes anything that can be substituted for this.

Further, in the present invention, the filler is often a powdered material of the same type as the aggregate, that is, stone powder, but it may also be other additives such as inorganic powder or a fibrous reinforcing material.

In the present invention, asphalt includes all asphalts that can be used for pavement, but straight asphalt is usually sufficient.

In the present invention, the ethylene-ethyl acrylate copolymer is obtained by polymerizing ethylene and ethyl acrylate under high pressure using a radical initiator.

In the present invention, the modified ethylene-ethyl acrylate copolymer refers to the ethylene-ethyl acrylate copolymer combined with an unsaturated carboxylic acid (e.g., acrylic acid, maleic acid, etc.) or a derivative thereof (e.g., maleic anhydride, ethyl acrylate, etc.). was obtained by heating at high temperature in the presence or absence of a solvent with or without the addition of a radical initiator.

The short fibers made of the resin of the present invention are produced by extruding the resin into fibers from an extruder, cooling the resin fibers in air to produce resin fibers, and cutting the resin fibers into short pieces using a cutter.

Preferred embodiments for producing improved road paving materials using the asphalt additive of the present invention are (1), (2), (3) and (4) below.

(1) Put various heated aggregates into a mixer, add a filler at room temperature, dry knead, and then reduce the viscosity.
Acid-modified ethylene-ethyl acrylate copolymer is used to produce heated asphalt road paving material by injecting and mixing asphalt heated to 150 to 300 centistokes in an amount of 4 to 20% by weight of the total paving material. Diameter consisting of union
Production of an improved heated asphalt road paving material characterized in that short fibers of 0.05 to 0.10 mm and length of 3 to 20 mm are pre-dosed and mixed into heated asphalt at 0.2 to 2.0% by weight of the total paving material. Method.

(2) Put various heated aggregates into a mixer, add a filler at room temperature, dry knead, and then reduce the viscosity.
Acid-modified ethylene-ethyl acrylate copolymer is used to produce heated asphalt road paving material by injecting and mixing asphalt heated to 150 to 300 centistokes in an amount of 4 to 20% by weight of the total paving material. Combine to 100 parts by weight,
After kneading 6 to 20 parts by weight of fibrous glass with a diameter of 0.005 to 0.150 mm, the powder is pulverized to a particle size of 6 to 35 mesh, and 0.2 to 2.0% by weight of the total paving material is pre-dosed onto heated asphalt. An improved method for producing a heated asphalt road paving material, characterized by mixing the heated asphalt road paving material.

(3) Put various heated aggregates into a mixer, add a filler at room temperature, dry knead, and then reduce the viscosity.
Acid-modified ethylene-ethyl acrylate copolymer is used to produce heated asphalt road paving material by injecting and mixing asphalt heated to 150 to 300 centistokes in an amount of 4 to 20% by weight of the total paving material. Diameter consisting of union
A method for producing heated asphalt road paving material with improved toughness and tenacity, characterized by mixing short fibers of 0.05 to 0.10 mm and length of 3 to 20 mm at 0.2 to 2.0% by weight of the total paving material. .

(4) Put the various heated aggregates into a mixer, add a filler at room temperature, dry knead, and then reduce the viscosity.
Acid-modified ethylene-ethyl acrylate copolymer is used to produce heated asphalt road paving material by injecting and mixing asphalt heated to 150 to 300 centistokes in an amount of 4 to 20% by weight of the total paving material. Combine to 100 parts by weight,
After kneading 6 to 20 parts by weight of fibrous glass with a diameter of 0.005 to 0.150 mm, pulverizing it and administering the powder with a particle size of 6 to 35 mesh at 0.2 to 2.0% by weight of the total paving material and mixing. A method for producing heated asphalt road paving material with improved toughness and tenacity. In particular, according to the methods (3) and (4) above, when mixing aggregate, filler, and asphalt with a conventional asphalt mixture manufacturing apparatus and method, short fibers or resin/fibers made of a predetermined amount of resin are weighed. A simple operation of adding powder consisting of a crushed glass kneaded material is sufficient, and there is no need to change the mixing time.

This method is extremely economical because it does not include any equipment or process cost increase factors when the process is automated or continuous.

The toughness and tenacity mentioned above and their test methods will be explained below.

Purpose and discussion of asphalt toughness and tenacity testing The main effects expected when resin and rubber are mixed and dissolved in asphalt are improvements in cohesive force and adhesion, and improvements in elasticity and impact resistance. .

As a method for measuring the effect of improving viscoelastic physical properties, there is a toughness/tenacity test proposed by Benson. In this method, a metal hemisphere of a certain size is buried with the spherical side facing down in an asphalt sample in a specified container, and when it is pulled out at a certain temperature and speed, the vertical axis is the load applied to the hemisphere, and the horizontal axis is the displacement. This is a test method that records information.

According to this test method, the load when the metal hemisphere is pulled out of the sample first appears in the form of a high mountain (large force), and then the force decreases rapidly as the asphalt is stretched thinner. The difference in the speed at which this force decreases and the way the curve is drawn vary depending on the properties of the sample.

The area of the high peak corresponds to the resistance of the asphalt as it grips the hemisphere, and this is called gripping force (toughness), and the area of the base corresponds to the asphalt sample's resistance to large deformation. In other words, it corresponds to caking property, and this is called tenacity. Both powers
It is expressed in units of kg・cm.

Example The present invention will be explained below with reference to Examples.

Example 1 Ethylene-ethyl acrylate copolymer produced by high pressure method (density 0.930, MI6, EA content 7%)
Modified with maleic anhydride is kneaded and melted in an extruder at 170℃, extruded through a fiber manufacturing nozzle to produce fibers with a diameter of 0.08 mm, and this is made into short fibers with a length of 3 to 20 mm. It was cut to

Next, 10 kg of asphalt with a penetration degree of 80 was put into 18 cans, stirred while heating and melting, and the short fibers were added to the asphalt at a concentration of 5%, and the toughness and tenacity were measured by the Benson method. However, they were 100Kg・cm and 45Kg・cm, respectively.

Comparative Example 1 Low-density polyethylene (density
0.920, MI20) was kneaded and melted at 170°C in an extruder and extruded through a fiber manufacturing nozzle to produce fibers with a diameter of 0.08 mm, which were cut into short fibers with a length of 3 to 20 mm.

Next, 10 kg of asphalt with a penetration degree of 80 was put into 18 cans, stirred while heating and melting, and the short fibers were added to the asphalt at a concentration of 5%, and the toughness and tenacity were measured by the Benson method. However, they were 50Kg・cm and 25Kg・cm, respectively.

Example 2 Ethylene-
Ethylene-ethyl acrylate copolymer obtained by copolymerizing ethyl acrylate (MI24, EA
content 35%) modified with maleic anhydride10
Kg, 0.08mm diameter, 5mm length fibrous glass approx.
Add 1000g and knead for 5 minutes at 150℃ using a kneader.
After cooling to room temperature, it was pulverized to obtain 6 to 35 meshes of granular material. Next, 10 kg of asphalt with a penetration degree of 80 was put into 18 cans, stirred while heating and melting, and the above powder and granules were put into the asphalt at a concentration of 5%, and the toughness and tenacity were measured by the Benson method. As a result, they were 147Kg・cm and 130, respectively.
It was Kg・cm.

Comparative Example 2 Approximately 1000 g of fibrous glass with a diameter of 0.08 mm and a length of 5 mm was added to 10 kg of low-density polyethylene (density 0.920, MI20) manufactured using a polyethylene manufacturing equipment using a high-pressure method, and kneaded at 150°C for 5 minutes in a kneader. After cooling to room temperature, the powder was crushed to obtain 6 to 35 meshes of powder.

Next, 10 kg of asphalt with a penetration degree of 80 was put into 18 cans, stirred while heating and melting, and the above powder and granules were put into the asphalt at a concentration of 5%, and the toughness and tenacity were measured by the Benson method. The weights were 60Kg・cm and 30Kg・cm, respectively.

Claims (1)

[Scope of Claims] 1. An additive for modified asphalt characterized by being short fibers made of an acid-modified ethylene-ethyl acrylate copolymer. 2. For use in modified asphalt, which is characterized in that it is a granular material in which fibrous glass with a diameter of 0.005 to 0.150 mm is kneaded into an acid-modified ethylene-ethyl acrylate copolymer, and then crushed to a particle size of 6 to 35 mesh. Additive.