JP2007131657A - Pavement material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an excellent resin mortar as a pavement material quickly curable at low temperature, having high strength, softness and durability and giving a multifunctional pavement material having softness or shock absorbing property as the whole pavement to meet the requirements for pavement materials comprising a certain extent of softness, i.e. high tensile elongation (elongation rate at tensile breakage) not to mention of high strength. <P>SOLUTION: The pavement material is a mixture of a one-pack moisture-curable urethane composition (a) and aggregate, and the cured material of the mixture has an open cell structure. The urethane composition (a) is a mixture of the first isocyanate compound having an isocyanate group content of 2-12 wt.% and the second isocyanate compound having an isocyanate group content of 25-40 wt.%. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a paving material.

The pavement material is a material used for road pavement, and is applied and filled on roadbeds, other ground, bridges, highways and the like.
Asphalt pavement is the most paved road and very good. Further, recently, permeable asphalt pavement has been used from the viewpoint of accidents caused by hydroplaning phenomenon caused by rainwater, noise problems, and the like.
This is because the asphalt used is reduced and there is a gap between the aggregates. This void allows water to permeate downward and reduce sound waves that cause noise. However, and inevitably structure weakened because of this gap, aggregate withdrawal is earlier damage scattered easily pavement.

  Therefore, it has been practiced to apply resin mortar as a reinforcing material to the asphalt pavement surface. This resin mortar prevents the separation and scattering of the aggregate. Almost all of such resin mortars are currently epoxy resins due to their price, cured material properties, workability, and the like.

  Recently, multifunctional functions such as reducing noise, preventing freezing on the road as much as possible, and ensuring water permeability have been demanded. In this, it is considered that the aggregate is an elastic body, and the entire paved body is made into an elastic structure, but in that case, the resin is epoxy, there is almost no elasticity, and it can not follow the deformation of the elastic body, The performance of the elastic body is not utilized, and the meaning of making the aggregate an elastic body is lost. Also, the epoxy resin itself has poor weather resistance, which is also a problem.

  Therefore, it is conceivable to use urethane having relatively elasticity, but the conventional one-pack type urethane resin has problems such as low temperature curability and curing time. Further, in the case of a one-pack type urethane resin, the foam often inevitably foams, and generally has a high viscosity and poor workability.

  As a paving material, strength is naturally necessary, but it is not only excellent in strength, but also preferably has a certain degree of flexibility, that is, a high tensile elongation (elongation rate at the time of tensile fracture). Thereby, the flexibility or shock absorption property of the entire pavement is given, and the above-mentioned multi-functional demand is answered. Therefore, the present invention provides a resin mortar that is excellent as a paving material that is rapidly cured at low temperatures, has a high strength, is flexible, and has durability.

In view of the situation as described above, the present inventor has completed the pavement material and the pavement method of the present invention as a result of earnest research. It is a mixture of a curable urethane composition and an aggregate, and the cured product of the mixture of both has continuous voids,
(A Mixture of a first isocyanate compound having an isocyanate group content of 2 to 12% by weight and a second isocyanate compound having an isocyanate group content of 25 to 40% by weight),
Furthermore, in the pavement method, the pavement material according to claim 1 is slid and filled into a gap existing on the road surface.

The first feature of the present invention is the urethane composition used, which is as described in a above.
The first isocyanate compound here has two or more isocyanate groups and is usually two, but may be three. Although it is possible to use four or more, the cured product becomes hard. Moreover, since it is usually a mixture of prepolymers having various degrees of polymerization, the number of isocyanate groups per molecule is preferably about 2.0 to 2.3.
The isocyanate group content of the first isocyanate compound is preferably 2 to 12% by weight in order to obtain a moderately flexible cured product, and if it is 12% by weight or more, the cured product is hard and brittle. On the other hand, if it is less than 2% by weight, the curing rate is low and the strength of the cured product is low, which is not preferable.

  Such a prepolymer usually has an isocyanate monomer such as diphenylmethane-4,4'-diisocyanate (MDI) and a polyhydric alcohol such as ethylene glycol, glycerin or polyether polyol, or a terminal chain having an ether bond. It is obtained by reaction with an oligomer having a hydroxyl group (molecular weight of about 400 or less).

  The isocyanate group content of this prepolymer is the molecular weight of the isocyanate group (42) × the number of isocyanate groups divided by the total molecular weight. In the case of two isocyanate groups, the content of 2 to 12% by weight means that the total molecular weight is 700 to 4200. Moreover, in the case of three isocyanate groups, it will be 1050-6300.

  Next, the second isocyanate compound has a lower molecular weight than the above-mentioned prepolymer and is usually a monomer. The isocyanate group content is 25 to 40% by weight. When this is calculated in the same manner as described above, when the number of isocyanate groups is two, the content of 25 to 40% by weight means that the total molecular weight is 210 to 336. Moreover, in the case of three isocyanate groups, it will be 315-504.

  Examples of the low molecular isocyanate compound include diphenylmethane-4,4′-diisocyanate (MDI), crude MDI, a reaction product of MDI and polyol, carbodiimide-modified MDI, and tolylene diisocyanate (TDI). A mixture thereof may also be used.

  A major feature of the present invention is that at least two types of isocyanate compounds, which are large and small, are mixed. In other words, the conventional prepolymer alone has a high viscosity and poor workability. In order to improve this, a lot of solvent must be used. Moreover, it is difficult to achieve uniform curing with only a low-molecular isocyanate compound, and foaming or partial curing failure occurs. Hardened | cured material has problems, such as a small elongation and being hard and brittle.

When blended as in the present invention, both disadvantages are compensated. The mixing ratio of the two types is preferably (first isocyanate compound) / (second isocyanate compound) (weight ratio) = 90/10 to 20/80. This range is excellent in workability and strength.
The total isocyanate group content in the mixture of the first and second isocyanate compounds is preferably 10 to 25% by weight. The reason is that if it is less than 10%, there is a problem that the resin liquid becomes highly viscous or the resin after curing becomes low strength, and if it exceeds 25%, the brittleness of the resin after curing becomes a problem.

  Furthermore, for example, a solvent of about 1 to 20 parts by weight may be mixed with 100 parts by weight of the first isocyanate compound. The solvent is preferably an ester type, and ethyl acetate or the like is preferable. Aromatic solvents are excellent in urethane solubility, but they hinder adhesion to the asphalt pavement surface, which is the work surface, and are likely to cause cutback. On the other hand, ethyl acetate or the like hardly affects the asphalt structure and does not inhibit the adhesion of the urethane resin.

Such a resin (mixed solution) may be mixed with other resins without departing from the object of the present invention. For example, a curing accelerator, a pigment, an ultraviolet absorber, and the like.
The resin mixture should be added with a curing accelerator containing a tertiary amine to adjust the curing speed (for summer and winter). To improve the workability of the resin, ethyl acetate is used to adjust the resin viscosity. By adding a pigment such as iron oxide, bengara, titanium oxide, etc. for coloring the resin and further coloring the resin, many practical functions are retained. Resin liquids containing these are stable and easy to handle.

  As physical properties of such a resin, the viscosity is 25 ° C., and it is preferably about 700 to 3000 mPa · S. The cured product has a tensile strength of 10 to 40 MPa, preferably 15 to 35 MPa, and a tensile elongation of 10 to 10 MPa. 100%, preferably about 12 to 50%. The strength and elongation are determined in accordance with JIS K6251. The shape of the test piece (film shape) at this time is a dumbbell No. 2 test piece, and the resin may generate gas by reaction to cause foaming. Therefore, the thickness of the test piece was set to 200 to 500 μm.

Aggregates are composed of organic substances, inorganic substances, composites or mixtures thereof, and 90% or more of them have a particle diameter of 20 mm or less. That 90% by weight or more has a particle diameter of 20 mm or less, that is, when passing through a sieve having an opening of 20 mm, the sieve passage rate may be 90% by weight or more. Specific examples include gravel, crushed stone, plastic pellets, rubber particles, and the like.
In the present invention, an elastic aggregate is preferable as the aggregate. The elastic aggregate is made of rubber or plastic and has deformation recovery properties. The hardness is preferably about soft urethane or an automobile tire. By using such an elastic aggregate, the entire pavement becomes flexible. The size of the aggregate may be about the same as that of a normal paving resin mortar. For example, it is about 0.1 to 10 mm.

  Furthermore, it is also preferable that the elastic aggregate is used as a core and the powder is fixed around it with an adhesive. Any adhesive may be used as long as it has a function of fixing the core material and the powder. Adherence does not necessarily have to be securely adhered, and it is only necessary to adhere with a certain amount of force.

  A preferred elastic aggregate adjustment method will be described. First, an adhesive is attached to the core. The method may be any method such as spraying, coating, dipping (so-called dobu-zuke), stirring and adhering in a container. The thickness of the adhesion is not limited as long as the powder can be fixed.

The powder may be fine particles or powder of silica sand, cement powder, charcoal cal, silica, inorganic powder such as ceramic, or organic powder such as plastic pulverized product, powder, granule or irregular shape It may be. They may be long ones such as fibers or fine powders such as fly ash. This is because chemical properties and reactions are not necessarily sought, but their physical existence and shape itself are sought first. Of course, it is still preferable if it is chemically fixed.
The size of the powder is about 0.01 μm to 1 mm, but may be larger depending on the size of the core material. The size of the powder may be determined based on the relative relationship with the core material.

  In order to fix the powder to the core material to which the adhesive has adhered, it is only necessary to cover the powder. For example, the core material coated with resin can be rolled in the powder, the powder can be sprayed on the core material, and the core material can be placed in a container containing the powder and stirred.

  Further, as the aggregate, an elastic aggregate and a normal hard aggregate may be mixed and used. Moreover, you may change with the size. Smaller ones are hard ceramics, and larger ones are elastic powder / resin coated waste tire rubber chips.

The paving material of the present invention has drainage or water permeability, and therefore, a cured product of a mixture of the one-component moisture-curing urethane composition and the aggregate must have continuous voids. The porosity is preferably 10 to 40% by volume.
Continuous voids mean that the voids are connected and not sealed. Therefore, in the pavement, fluid such as water or air can be passed by gravity or pressure. The porosity of the continuous voids can be measured by a method of measuring the weight of the molded body and the weight of the molded body immersed in water and removing the gas in the continuous voids, that is, a method based on the Archimedes principle. it can. The reason why the porosity of 10 to 40% by volume is suitable is that if it is less than 10%, the water permeability when it is used as a paving material is insufficient, and if it is higher than 40%, the mechanical strength of the paving material is insufficient. is there.

The ratio of the aggregate and the urethane resin is appropriately 100: (8 to 30) (weight ratio) although it depends on the density of the aggregate.
The aggregate is covered with a urethane resin film, and the aggregates are bonded together. Since the urethane resin is a one-component moisture-curing type, the reaction proceeds due to moisture and releases carbon dioxide. Gas is released into the voids through the membrane on the surface of the aggregate, but a structure without continuous voids, for example, if the resin ratio is too high, it becomes a closed space instead of voids and expands, that is, foams, due to the generated gas. become. Naturally, it is further inappropriate in a dense-grained state where there is little enclosed space.

The one-component moisture curable urethane resin of the present invention has a large strength and a low elongation as compared with a normal urethane resin. For example, the urethane resin of the present invention exhibits extremely desirable performance when the aggregate is a crushed product (granular) of the tire as the core and the powder is fixed to the periphery with an adhesive. If the pavement material (cured material) that is paved on the road surface is deformed by hundreds of percent, it is considered that it will lead to great destruction, and there will be a problem in running the vehicle. The resin of the present invention can withstand deformation of the pavement (for example, when compressed) by several tens of percent. This is because the deformation (elongation) of the resin film adhering to the surface can be considerably small with respect to the deformation of the volume. By suppressing the elongation, the strength of the resin is increased, and thereby the elastic aggregate is strongly restrained. Therefore, the paving material becomes durable. However, as a result, it is meaningless to lose the noise reduction and freezing suppression effect of the elastic aggregate. However, tests on actual roads (roads in which the resin mortar of the present invention is rubbed and filled on ordinary granulated ascon pavement) have been demonstrated to exhibit excellent noise reduction effects and anti-freezing effects.
The urethane resin of the present invention exhibits elasticity. Even if it deforms, it recovers instantly and returns to its original shape. Resins that are not elastic (for example, epoxy resins) are slow in recovery of deformation, and eventually undergo destruction when changes due to impact are repeatedly applied.

The method for preparing and using the pavement material of the present invention is as follows.
For example, if the surface-treated rubber chip (powder / resin-coated) is used as an aggregate, the pavement is mixed at a processed rubber chip: urethane resin binder = 100: 20 (parts by weight) to prepare a resin mortar. Here, the resin binder is prepared by adding an additive in order to adjust the curing speed and pot life according to the atmosphere and external weather conditions, or to improve the workability.
1 to 20 parts by weight of a curing accelerator mixture is added to and mixed with 100 parts by weight of a urethane resin for binder (a mixture of a first isocyanate compound and a second isocyanate compound), and this is used.
The mixture consists of (1) a composition containing a tertiary amine as an essential component, (2) ethyl acetate, and (3) a pigment. When there is no need to accelerate curing (1), when viscosity adjustment is not required (2), and (3) may be unnecessary when it is not necessary to further color the resin mortar. Depending on the case, it may be used by appropriately selecting from (1), (2), (3).
Such a mixture may be applied, laid, constructed, coated, etc. before curing (within the pot life).

In the case of this invention, there exists an advantage that the pot life of resin mortar (for pavement) is comparatively long, and a cure rate is quick. This is also an effect of mixing the second isocyanate compound.
The pot life is about 15 to 30 minutes, and the openable time as a paved road can be about 1.5 to 5 hours. This is an epoch-making value compared to the conventional similar pavement material.

The paving material of the present invention can be applied not only to the above-described water-permeable paving but also to any passage. The laying method includes a method of cutting and filling (coating) the surface gap of the paved road, a method of laminating and applying, and a method of performing both.
The method of applying by sliding is a method in which the gap is mainly filled in the permeable asphalt pavement, which is the work surface, but as a rule it is not applied beyond the surface of the asphalt. Therefore, as a specific method, the resin mortar that is applied to the gap with a leveling tool and a tool for rubbing (including a mechanical device) and is placed over the asphalt pavement surface is removed in principle. In this method, the height of the paved surface is not substantially changed.

  In the method of laminating and applying to the surface layer or more of the work surface, the gap on the asphalt pavement surface, which is the work surface, is filled to some extent, but it is applied several mm to several cm above the asphalt surface. is there. In this method, when there is a large unevenness on the asphalt pavement surface of the work surface, it can be corrected.

The paving material and paving method of the present invention have the following great advantages.
(1) Workability is very good because the viscosity of the resin can be adjusted.
(2) Good low-temperature curability and can be used in winter and cold regions.
(3) Since the target paving material has a structure having continuous voids, the foaming problem of the one-component moisture-curing urethane that is the binder resin is substantially avoided by defoaming from the thin film.
(4) The urethane composition binder constituting the coating material of the present invention has excellent strength and moderate flexibility when mortar is formed with the elastic aggregate. Therefore, when surface coating is performed as a paving material, it exhibits excellent durability, noise reduction, freezing suppression, and other effects.

  Hereinafter, it demonstrates in detail along an Example.

First, examples of resin components (resin examples) are shown.
Resin example 1
The first isocyanate compound is 87 parts by weight, and the second isocyanate compound is 13 parts by weight. A reaction product of polyether polyol and MDI was employed as the first isocyanate compound (isocyanate group content: 7% by weight). Moreover, MDI was employ | adopted for the 2nd isocyanate compound (content of an isocyanate group is 30 weight%). In addition, the isocyanate content of the mixture of both isocyanate compounds was 10%.

  Similarly, resin examples 2 and 3 were prepared by using the same first isocyanate compound and second isocyanate, and changing only the mixing ratio.

Resin Example 4
A resin composition 4 was prepared by adjusting a 60:40 weight ratio mixture of the first isocyanate compound (isocyanate content 11%) and the second isocyanate compound (isocyanate content 38%). The total isocyanate group content of the mixture was 22% by weight.

Resin Example 5
A resin composition 5 was prepared by adjusting a 50:50 weight ratio mixture of the first isocyanate compound (isocyanate content 4%) and the second isocyanate compound (isocyanate content 25%).

Resin Comparative Example Only the first isocyanate (same as resin example 1) was used as resin comparative example 1, and only the second isocyanate (same as resin example 1) was used as resin comparative example 2. . Further, a resin comparative example 3 was prepared as a material containing both of them and outside of the present invention. It is a 75:25 weight ratio mixture of the first isocyanate compound (isocyanate content 16%) and the second isocyanate compound (isocyanate content 35%).

The solution physical properties of these resins and the physical properties when formed into films were measured. The results are shown in Table 1. Here, in the balance between the tensile strength and the tensile elongation, ◎ is good as a whole, ◯ is a degree where a sufficient effect is recognized, and X is almost no effect.

From Table 1, it can be seen that the first isocyanate and the second isocyanate alone are too soft or too hard. Moreover, it turns out that it becomes hard even if there is too much isocyanate content of 1st isocyanate from the comparative example 3 of resin.
Moreover, also in the Example of resin, it turns out that the isocyanate content of the mixture of 1st isocyanate and 2nd isocyanate influences hardness.

Examples of these respective resins were mixed as described below to obtain examples and comparative examples of the pavement material of the present invention.
(1) Resin: 100 parts by weight (2) Aggregate: 500 parts by weight A rubber tire crushed product (0.5 to 2.5 mm) obtained by bonding charcoal powder using a resin was used.
(3) Curing accelerator: 11 parts by weight A mixture of a tertiary amine curing agent (5% by weight), ethyl acetate (93% by weight), and a pigment (iron oxide: 2% by weight) was used.
First, after mixing resin and a hardening accelerator, this was stirred and mixed with the aggregate. This completes the paving material.

This pavement was rubbed into the surface aggregate gap of a normal water-permeable asphalt pavement (13 mm top aggregate) to a depth of about 15 mm in an amount of 1.1 Kg / m ² . Thereafter, rolling was performed with a rubber roller, and an operation for increasing the bonding of the aggregate was performed. Table 2 shows the effects of these examples and comparative examples.

The pot life of the prepared examples of pavement materials was 15 to 20 minutes, and the work could be performed slowly. The resin was sufficiently cured in 3 hours after coating, and as a result, the car was able to pass.
The balance between the strength and the flexibility in Table 2 was judged by whether or not it had sufficient flexibility while ensuring the strength as a paved road. X indicates whether the strength is insufficient or the flexibility is insufficient. In the examples, all were well balanced.

Claims (10)

A pavement characterized in that it is a mixture of a one-component moisture-curing urethane composition and an aggregate of the following a, and a cured body of the mixture of both has continuous voids,
a Mixture of a first isocyanate compound having an isocyanate group content of 2 to 12% by weight and a second isocyanate compound having an isocyanate group content of 25 to 40% by weight.   The pavement material according to claim 1, wherein the void ratio of the continuous gap is 10 to 40% by volume.   The pavement material according to claim 1 or 2, wherein the total isocyanate group content of the one-component moisture-curable urethane composition is 10 to 25% by weight.   The second isocyanate compound is one or more substances selected from diphenylmethane-4,4'-diisocyanate (MDI), crude MDI, a reaction product of MDI and polyol, and a carbodiimide-modified MDI. Paving material.   The paving material according to claim 1, wherein the cured product of the one-component moisture-curable urethane composition has a tensile strength of 15 to 40 MPa and a tensile elongation of 10 to 100%. The mixing ratio (weight ratio) of the first isocyanate compound and the second isocyanate compound is 90/10 to 20/80, and one or more components selected from the following materials are further added. 1-5 paving materials,
A curing accelerator containing a tertiary amine,
・ Ethyl acetate ・ Pigment   The pavement according to any one of claims 1 to 6, wherein the aggregate is composed of an organic substance, an inorganic substance, a composite thereof or a mixture thereof, and 90% by weight or more thereof has a particle diameter of 20 mm or less.   The pavement material according to claim 7, wherein the organic substance is an elastic body.   9. The pavement material according to claim 8, wherein the organic material is a material in which an elastic body is used as a core material and powder is fixed around the core material. 2. A road pavement method comprising filling the pavement material according to claim 1 into a gap existing on a road surface.