JP2019194323A - Heat insulation coating composition having aqueous two-liquid curability, heat insulation paint coating method, and heat insulation pavement - Google Patents

Abstract

To provide a heat insulation coating composition that can exhibit not only sufficient heat insulation property as an aqueous two-liquid type coating composition to be coated on an asphalt pavement, but also can form a coating having coating strength, durability of a degree applicable also to a carriage way, and has excellent quick-drying property, a heat insulation paint coating method, and a heat insulation pavement.SOLUTION: A heat insulation coating composition including: as a coating forming binder component, a main agent including a hydroxide group-containing normal temperature cross-linking polymer emulsion polyol in which polyurethane having a hydrazine structure and a carbonyl group-containing acrylic polymer are contained, hydroxy group-containing acryl emulsion polyol, and hydroxy group-containing polyurethane dispersion polyol, furthermore, as needs arise, cellulose nanofiber as a coating strength improving agent, and a coloring pigment; and a reactive film-forming aide made of a polymer that cures a film by a cross-linking reaction with a binder functioning also as a curing agent.SELECTED DRAWING: Figure 1

Description

  TECHNICAL FIELD The present invention relates to a heat-shielding coating composition for a water-based protective finish coating applied as a topcoat coating material mainly on road pavements such as asphalt pavement, and more particularly to an aqueous two-component room temperature crosslinking type heat-shielding coating composition. And a coating method using the same, and a heat-shielding pavement.

Due to the heat island phenomenon in urban areas in recent years and global weather fluctuations, etc., for pavements such as road surfaces, a thermal barrier coating layer is formed by applying a thermal barrier paint to the paved surfaces such as asphalt pavement and concrete pavement, In other words, thermal barrier paving is increasingly used. On the other hand, when the thermal barrier coating layer is formed on the roadway even on the road surface, higher coating film strength and durability than the sidewalk, particularly high peeling resistance and wear resistance are required.
As the paint used for the thermal barrier coating layer of the roadway, conventionally, a thermal barrier paint mainly composed of a solvent-type MMA (methyl methacrylate) resin is used. In this type of MMA thermal barrier paint, At the same time as the heat-shielding properties, it exhibits considerable coating strength and durability.

  However, since the MMA-based thermal barrier paint is a solvent type, there are concerns about environmental hygiene and safety. Therefore, it is desired to apply a room temperature drying-type water-based paint (emulsion paint) advantageous in these aspects to pavement of roadways.

  As water-based heat-shielding paint used for a heat-shielding coating layer on a pavement surface such as a sidewalk or a park, for example, those shown in Patent Document 1 and Patent Document 2 are known. However, conventional general water-based thermal barrier paints can be applied to sidewalks, but when applied to roadways, the coating strength and durability are markedly higher than those of solvent-type MMA thermal barrier paints. There is an inferior problem. In particular, there is a problem in terms of durability, such as a decrease in strength due to the influence of water due to rain on the road surface, and on a roadway through which a heavy vehicle passes, it is unavoidable that problems such as early wear and peeling occur. .

  Also, conventional water-based thermal barrier paints have poor drying properties (quick drying), and it takes a considerable amount of time from application to drying, so that the coating is sufficiently dried after the start of construction. Until then, there is a problem of requiring long-time traffic regulation. For these reasons, it has been said that conventional water-based thermal barrier paints are not necessarily suitable for use in paving road surfaces.

  As described above, conventionally, there are few satisfactory water-based paints for improving the heat-shielding performance of the paved surface, and it has excellent heat-shielding properties, and at the same time, is particularly strong and durable enough to be suitable for roadways. In fact, there was nothing that was sustainable for a long time and was excellent in quick-drying during construction.

Japanese Patent Laid-Open No. 2-105879 Japanese Patent Laid-Open No. 1-301761

  The present invention has been made in the background as described above, and is basically an aqueous two-component type that is coated to improve heat insulation as a top coat material on the surface of a paving substrate such as asphalt pavement. As a coating composition, the coating composition has sufficient heat shielding properties to not only reliably suppress the increase in road surface temperature, but also has sufficient coating strength and durability that can be applied to roadways. It is an object to provide a thermal barrier coating composition that can form a film and also has excellent drying properties (fast drying), a thermal barrier coating method using the thermal barrier coating composition, and a thermal barrier pavement. .

  In order to solve the above-mentioned problems, the present inventors have conducted extensive experiments and studies. As a result, a non-solvent aqueous two-component coating composition is used as a top coat material for improving the heat shielding property of the paved road surface. Is a polymer system in which the coating film-forming binder component dispersed in the aqueous medium in the main agent is a component system composed of three specific polyols, and further causes a crosslinking reaction with the main film-forming binder component to cure the coating film. It has been found that it is effective to add a reactive film-forming auxiliary comprising the above, and it has been found that it is even more effective to add cellulose nanofiber as a coating strength improver to the main agent. .

That is, the heat-shielding coating composition having aqueous two-component curability according to the basic aspect (first aspect) of the present invention is:
Hydroxyl group-containing room temperature cross-linked polymer emulsion polyol (A) containing polyurethane having a hydrazine structure and a carbonyl group-containing acrylic polymer as particles of a film-forming binder component dispersed in an aqueous medium, and a hydroxyl group-containing acrylic emulsion polyol A main agent containing (B) and a hydroxyl group-containing polyurethane dispersion polyol (C) and containing a colored pigment;
A reactive film-forming auxiliary agent that also serves as a curing agent, comprising a polymer that causes a crosslinking reaction with the film-forming binder component of the main agent to cure the coating film;
It is characterized by comprising.

Moreover, the heat-shielding coating composition having aqueous two-component curability according to the second aspect of the present invention is the heat-shielding coating composition according to the first aspect,
The main agent contains cellulose nanofiber as a coating film strength improver.

Moreover, the heat-shielding coating composition having aqueous two-component curability according to the third aspect of the present invention is the heat-shielding coating composition according to the second aspect,
The ratio of the cellulose nanofibers in the whole main agent is in the range of 0.01 to 10.0% by weight.

Furthermore, the thermal barrier coating composition having an aqueous two-component curability according to the fourth aspect of the present invention is the thermal barrier coating composition according to any one of the first to third aspects.
The blending ratio of the hydroxyl group-containing room temperature cross-linked polymer emulsion polyol (A) in the entire coating film forming binder component is in the range of 50 to 90% by weight, and the blending ratio of the hydroxyl group-containing acrylic emulsion polyol (B) is 10 to 40. The blending ratio of the hydroxyl group-containing urethane dispersion polyol (C) is within the range of 5% by weight to 30% by weight.

Moreover, the heat-shielding coating composition having an aqueous two-component curability according to the fifth aspect of the present invention is the heat-shielding coating composition according to any one of the first to fourth aspects.
The hydroxyl group-containing room temperature cross-linked polymer emulsion polyol (A) has a hydroxyl value of 10 to 30 mg KOH / g and a glass transition temperature (Tg) of 25 to 45 ° C.,
The hydroxyl group-containing acrylic emulsion polyol (B) has a hydroxyl value of 50 to 70 mg KOH / g and a glass transition temperature (Tg) of 30 to 50 ° C.,
The hydroxyl group-containing urethane dispersion polyol (C) has a hydroxyl value of 40 to 60 mg KOH / g and a glass transition temperature (Tg) in the range of −30 to −10 ° C.

The heat-shielding coating composition having an aqueous two-component curability according to the sixth aspect of the present invention is the heat-shielding coating composition according to any one of the first to fifth aspects.
The hydroxyl group-containing room temperature cross-linked polymer emulsion polyol has an average particle size of 130 to 230 nm, the hydroxyl group-containing acrylic emulsion polyol has an average particle size of 90 to 140 nm, and the hydroxyl group-containing polyurethane dispersion polyol has an average particle size of 40 to 90 nm. It is characterized by.

The heat-shielding coating composition having aqueous two-component curability according to the seventh aspect of the present invention is the heat-shielding coating composition according to the sixth aspect,
The heat-shielding colored pigment is one or more selected from titanium oxide, iron oxide, and complex oxide pigments.

The heat-shielding coating composition having an aqueous two-component curability according to the eighth aspect of the present invention is the heat-shielding coating composition according to any one of the first to seventh aspects.
The reactive film-forming aid also serving as a curing agent is made of polyisocyanate.

The heat-shielding coating composition having an aqueous two-component curability according to the ninth aspect of the present invention is the heat-shielding coating composition according to the eighth aspect,
The blending ratio of the reactive film-forming aid composed of polyisocyanate and the film-forming binder component in the main agent is such that the molar ratio of the isocyanate group of the reactive film-forming aid to the hydroxyl group of the polyol in the film-forming binder component. It is within the range of 0.8 to 1.1.

  In the next tenth aspect, the thermal barrier coating composition of each aspect described above was used as a top coat coating method for a paved surface using the thermal barrier coating composition having aqueous two-component curability of each aspect. The thermal barrier paint painting method is prescribed.

That is, the thermal barrier paint coating method of the tenth aspect of the present invention is:
The main agent and the reactive film-forming aid in the heat-shielding coating composition having the aqueous two-component curability according to any one of the first to ninth aspects are kneaded to form an aqueous coating, and the aqueous coating is paved. It is characterized by being coated on a substrate.

  Furthermore, in the following 11th-13th aspect, the heat-shielding pavement which performed the top coat coating to the pavement surface is prescribed | regulated using the heat-shielding coating composition which has aqueous | water-based 2 liquid curability.

That is, the heat-shielding pavement of the eleventh aspect of the present invention is
A heat-shielding pavement in which a heat-shielding coating film is formed on the surface of the pavement substrate,
The thermal barrier pavement is
Hydroxyl group-containing room temperature cross-linked polymer emulsion polyol (A) containing a hydrazine structure polyurethane and a carbonyl group-containing acrylic polymer, a hydroxyl group-containing acrylic emulsion polyol (B), and a hydroxyl group-containing polyurethane disper as coating film forming binder components A main agent containing a colored pigment and a John polyol;
A reactive film-forming auxiliary agent that also serves as a curing agent, comprising a polymer that causes a crosslinking reaction with the film-forming binder component of the main agent to cure the coating film;
Consists of
Each of the polyols and the reactive film-forming aid are cross-linked.

The heat-shielding pavement of the twelfth aspect of the present invention is
In the heat-shielding pavement of the eleventh aspect,
The main agent is characterized by containing cellulose nanofiber as a coating film strength improver.

The heat-shielding pavement of the thirteenth aspect of the present invention is
In the heat-shielding pavement according to any of the eleventh and twelfth aspects,
The pavement base material is asphalt, concrete, or rubber chip urethane.

  In addition, also in the heat-shielding pavement of said 11th-13th aspect, as a coating composition, what was described in the 2nd-9th aspect can be used.

  According to the heat-shielding coating composition of the present invention, for example, as an aqueous two-component coating composition that is applied to improve the heat-shielding property as a topcoat material for pavements such as asphalt pavement, it exhibits sufficient heat-shielding properties. In addition, it is possible to reliably suppress an increase in road surface temperature, and to form a coating film that has high strength and is excellent in durability, in particular, peeling resistance and abrasion resistance, and is quick-drying It is also excellent, and various effects can be exhibited, such as shortening the traffic regulation time even in painting work on the road.

It is a rough solution sectional view showing typically the section structure of an example of the heat-shielding pavement formed using the heat-shielding paint constituent of the present invention. It is a graph which shows the indoor irradiation test result for the road surface temperature reduction performance evaluation in an experiment example. It is a graph which shows the peeling resistance test result by the twist method for durability evaluation in an experiment example. It is a graph which shows the peeling resistance test result by the impact method for durability evaluation in an experiment example. It is a graph which shows the peeling resistance test result before and behind the wet track test by the twist method for durability evaluation in an experiment example.

  Hereinafter, the thermal barrier coating composition of the embodiment of the present invention will be described in more detail.

  In the present invention, an aqueous two-component room temperature cross-linking type thermal barrier coating composition used as a top coat coating material for adding a thermal barrier function to a paving surface such as asphalt paving is defined. Here, the two-component cross-linking type heat-shielding coating composition according to the present invention has a reactive film-forming auxiliary agent mainly comprising a coating film-forming binder component and also serving as a curing agent. Moreover, it is more preferable that the main component of the two-component crosslinking type heat-shielding coating composition according to the present invention contains cellulose nanofiber (CNF) as a coating film strength improver in addition to the coating film forming binder component.

  The main component is a hydroxyl group-containing room temperature cross-linked polymer emulsion polyol (A) containing three types of resins (polyols) each having a hydroxyl group as a coating film forming binder component, that is, a polyurethane having a hydrazine structure and a carbonyl group-containing acrylic polymer. ), A hydroxyl group-containing acrylic emulsion polyol (B), and a hydroxyl group-containing polyurethane dispersion polyol (C). The main agent further contains a colored pigment (preferably a heat-shielding colored pigment) in addition to these three types of polyols. The main agent preferably contains cellulose nanofibers as a coating film strength improver in addition to the above three types of polyols and colored pigments.

  Then, a reactive film-forming aid that also serves as a curing agent is mixed (kneaded) with an aqueous medium such as water, which is a dispersion medium, in the stage immediately before the coating work, and paving such as asphalt as an aqueous paint. It will be painted on the surface of the substrate.

FIG. 1 shows an aqueous solution comprising a heat-shielding coating composition of the present invention (however, in this example, a heat-shielding coating composition containing cellulose nanofibers as a main agent) on a pavement substrate 1 made of, for example, concrete or an asphalt mixture layer. The state where the two-component paint is applied to form the heat-shielding coating film 3 is schematically shown.
In actual construction, a ply layer (not shown) is formed on the surface of the pavement substrate 1, and then the aqueous two-component paint composed of the heat-shielding coating composition of the present invention is applied to the surface of the primer layer. However, in this specification, including the case where a primer layer is formed in advance, it is expressed as “painting a water-based two-component paint comprising the heat-shielding coating composition of the present invention on a paving substrate”.

  The heat-shielding coating film 3 in this example is composed of three types of resins (hydroxyl group-containing room temperature cross-linked polymer emulsion polyol (A), hydroxyl group-containing acrylic emulsion polyol (B), and hydroxyl group-containing polyurethane) which are the binder resin components of the main agent as described above. Cellulose nanofibers 32 are intertwined in a resin matrix 31 formed integrally with the dispersion polyol (C)) and an auxiliary agent that also serves as a curing agent and a reactive film-forming auxiliary agent. For example, a heat-shielding colored pigment 33 as a pigment is dispersed. Here, the aggregate as an anti-slip material added as necessary is not shown.

  In the present invention, three types of resins (hydroxyl group-containing room temperature cross-linked polymer emulsion polyol (A), hydroxyl group-containing acrylic emulsion polyol (B), and hydroxyl group-containing polyurethane dispersion polyol (C)) are blended as the binder resin component of the main component. is important. That is, quick drying and strength can be ensured by blending the above three types of resins. Furthermore, the presence of cellulose nanofibers (CNF) in a mesh form in the coating can further improve the strength of the coating, thereby improving the durability of the coating, particularly the abrasion resistance and peeling resistance. As a result, it has become fully applicable not only to sidewalks but also to roadways.

  Here, the effectiveness of the blending of the above three types of resins and the effectiveness of the blending of the cellulose nanofibers are found by experiments of the present inventors shown as the following experimental examples.

[Experimental example]
The composition of the thermal barrier coating composition of the present invention used in this experiment is as follows.
As particles for coating film forming binder components.
A hydroxyl group-containing room temperature cross-linked polymer emulsion polyol (A) containing a polyurethane having a hydrazine structure and a carbonyl group-containing acrylic polymer,
-Hydroxyl-containing acrylic emulsion polyol (B),
・ Hydroxyl-containing polyurethane dispersion polyol (C),
These three types of polyol particles were blended, and further, cellulose nanofibers and reactive film-forming aids, and heat-shielding colored pigments and aggregates were blended.
Specifically, the hydroxyl group-containing room temperature cross-linked polymer emulsion polyol (A) containing a polyurethane having a hydrazine structure and a carbonyl group-containing acrylic polymer has a hydroxyl value of 20 mgKOH / g and a glass transition temperature (Tg) of 35. The average particle size is 180 nm, and the hydroxyl group-containing acrylic emulsion polyol (B) has a hydroxyl value of 60 mgKOH / g, a glass transition temperature (Tg) of 40 ° C., and an average particle size of 120 nm. As the hydroxyl group-containing polyurethane dispersion polyol (C), a hydroxyl group value of 50 mg KOH / g, a glass transition temperature (Tg) of −20 ° C., and an average particle size of 60 nm were used. Moreover, polyisocyanate was used as a reactive film-forming aid.

  The ratio of the hydroxyl group-containing room temperature cross-linked polymer emulsion polyol (A) is 21% by weight, the ratio of the hydroxyl group-containing acrylic emulsion polyol (B) is 10.5% by weight, and the ratio of the hydroxyl group-containing polyurethane dispersion polyol (C) is 3. .5% by weight, cellulose nanofibers are blended so that the ratio of cellulose nanofibers is 2.0% by weight, and silica sand as an aggregate is blended to be 58.0% by weight. Further, titanium oxide having an average particle diameter of 1.0 μm as a heat-shielding colored pigment is blended so as to be 4.5% by weight, and further a composite oxide having an average particle diameter of 1.1 μm is 0.5% by weight. It mix | blended so that it might become.

Such a compounding material, a polyisocyanate as a reactive film-forming aid, its isocyanate group (-NCO), and a hydroxyl group (-OH) of a polyol (total of three types of polyol) as a coating film forming binder component The aqueous paint is mixed so that the molar ratio is 1.0, and the coating is applied to the asphalt pavement surface twice so that the coating amount per unit area is 600 g / m ^2, and is dried at around room temperature. A thermal barrier pavement having a top coat layer of the composition was obtained. The coating thickness after drying is about 500 to 600 μm on average.

  The thermal barrier pavement (hereinafter referred to as “the thermal barrier of the present invention”) with such a coating composition of one embodiment of the present invention was evaluated as follows. For comparison, we also evaluated a thermal barrier pavement with an overcoat layer using conventional water-based thermal barrier paint (conventional emulsion-based thermal barrier paint) (hereinafter referred to as “conventional thermal barrier pavement”). In some cases, thermal barrier pavement having an overcoat layer made of MMA thermal barrier paint (solvent thermal barrier paint) (hereinafter referred to as “MMA thermal barrier pavement”) was also evaluated.

The blending composition and application conditions of the conventional general water-based thermal barrier paint (conventional emulsion-based thermal barrier paint) are as follows.
Titanium oxide: 10% by weight, organic black pigment: 1% by weight, calcium carbonate: 10% by weight, acrylic emulsion resin component: 15% by weight, silica sand: 33% by weight, other water and additives: 31% The product was a water-based thermal barrier paint. As a coating condition, a sample coated 500 g / m ² × 2 times was used as a comparative body.
In addition, the composition and application conditions of the MMA thermal barrier coating which is a solvent thermal barrier coating are as follows.
A mixture of titanium oxide: 10% by weight, organic black pigment: 1% by weight, calcium carbonate: 10% by weight, and curable MMA resin: 80% by weight was used. This was cured by adding 0.9% by weight of organic amine and 2.4% of benzoyl peroxide. As a coating condition, 400 g / m ^{2 was} applied as an undercoat, 500 g / m ^{2 of} ceramic aggregate was sprayed, and then 400 g / m ² was further applied as a top coat.

<Evaluation of road surface temperature reduction performance>
Table 1 shows the measurement results comparing the solar reflectance of the thermal barrier pavement of the present invention with that of a conventional thermal barrier pavement. From this result, it was found that the thermal barrier pavement of the present invention showed a solar reflectance of 70% or more in the near infrared region, and had the same solar reflectance characteristics as the conventional thermal barrier pavement. Moreover, in the indoor irradiation test conducted for performance confirmation, as shown in FIG. 2, it confirmed that it provided the road surface temperature rise suppression performance comparable with the conventional heat-shielding pavement. In FIG. 2, “general pavement” means asphalt pavement that does not have a top coat layer for heat insulation. In these evaluation tests, as the thermal barrier pavement of the present invention, as described above, a material in which cellulose nanofibers are added to the main agent is used, but even when cellulose nanofibers are not added, FIG. It has been confirmed that the solar reflectance characteristics and the road surface temperature rise suppressing performance substantially equivalent to those of the thermal barrier pavement of the present invention shown in FIG.

<Evaluation of physical properties of coating film>
In order to confirm the abrasion resistance and drying property of the coating film, a Taber abrasion test and a quick drying property evaluation were performed. As shown in Table 2, it can be seen that the thermal barrier pavement of the present invention is superior in wear resistance compared to the conventional thermal barrier pavement. Even in the evaluation of quick-drying property, it was confirmed that the thermal barrier pavement of the present invention was dried at a curing time of about 1/3 as compared with the conventional thermal barrier pavement even under the condition of 5 ° C., and the drying property was improved. In this evaluation test, the thermal barrier pavement of the present invention uses the above-mentioned main agent added with cellulose nanofibers. However, even when cellulose nanofibers are not added, the thermal barrier pavement of the present invention shown in Table 2 is used. It has been confirmed that it exhibits almost the same wear resistance and dryness as thermal pavement.

<Durability evaluation: Peel resistance>
In order to examine the durability of the thermal barrier pavement of the present invention, a thermal barrier material was applied to porous asphalt, and then a peeling resistance test was performed. As this invention thermal insulation pavement, what added the cellulose nanofiber (CNF) to the above main ingredients, and the thing which does not add a cellulose nanofiber (CNF) (about compounding other than CNF, what added CNF, and The same was applied to these CFF-added products and those without CNF added. Moreover, as a comparative example, tests were similarly conducted on a conventional thermal barrier pavement and an MMA thermal barrier pavement mainly applied to a roadway.
FIG. 3 shows the test results obtained by the twist method. As a result, the thermal barrier pavement of the present invention to which CNF was added had a peel area ratio of about 50% compared to the conventional thermal barrier pavement, and the peel resistance was greatly improved. This can also be confirmed from the test results by the batting method shown in FIG. In addition, the peeling resistance of the thermal barrier pavement of the present invention to which CNF is added is a result comparable to that of the MMA thermal barrier pavement. These are presumably because the toughness of the coating film was improved by the cellulose nanofiber added in this experiment. In addition, it is clear from FIGS. 3 and 4 that the peeling resistance of the thermal barrier pavement of the present invention to which CNF is not added is considerably improved as compared with the conventional thermal barrier pavement.

<Durability evaluation: Peel resistance after weather resistance test>
In order to examine the durability of the thermal barrier pavement of the present invention to which CNF was added after the start of service, a peeling resistance test (twist method) was performed after a weather resistance test (50 hours irradiation) with a metal halide lamp. The test results are shown in FIG.
The results show that the thermal barrier pavement of the present invention has a peel area ratio of about 50% after the weather resistance test as compared with the conventional thermal barrier pavement, and satisfies the standard value even after the test. As a result, it was confirmed that the weather resistance was greatly improved compared to the conventional thermal barrier pavement. Even when compared with the MMA type thermal barrier pavement, the difference in the peeled area ratio is within 10%, and the thermal barrier pavement of the present invention has good weather resistance. In addition, it has been confirmed that the thermal barrier pavement of the present invention to which CNF is not added has good weather resistance.

<Durability evaluation: Water resistance by wet track test>
In order to evaluate the water resistance of the coating film, a wet track test used in the evaluation of the emulsion surface treatment method was conducted.
Table 3 shows the peeled area ratio of the coated surface before and after the wet track test for the thermal barrier pavement of the present invention to which CNF is added and the conventional thermal barrier pavement. The results show that the abrasion resistance of the conventional thermal barrier pavement is significantly reduced due to the influence of water immersion, whereas no peeling was confirmed in the thermal barrier pavement of the present invention. From this, it was found that the thermal barrier pavement of the present invention immediately after construction had excellent water resistance. In addition, it has been confirmed that the thermal barrier pavement of the present invention to which CNF is not added has better water resistance than the conventional thermal barrier pavement.

<Construction site evaluation>
In order to confirm the workability and quality at the site, on-site test construction was performed in which the thermal barrier pavement section of the present invention to which CNF was added and the conventional thermal barrier pavement section were provided. The outside temperature at the time of construction was about 5 ° C., and spraying was performed with a lysing gun. The coating width at the time of construction was uniform, and it was completely dried about 90 minutes after coating. Therefore, it was judged that the workability and drying property of the thermal barrier pavement of the present invention were good.
On the next day of construction, an actual vehicle stationary test was conducted in order to confirm peeling resistance. From the results shown in Table 4, partial peeling was confirmed in the conventional thermal insulation pavement, whereas in the thermal insulation pavement of the present invention, no peeling was seen and it was sound. From this, it was confirmed that the thermal barrier pavement of the present invention is excellent in quick drying and durability, and can be expected to be applied on a roadway. In the case of the thermal barrier pavement of the present invention to which CNF is not added, it has been confirmed that it has better quick drying properties and durability than the conventional thermal barrier pavement.

From each evaluation result as described above, a heat-shielding coating composition (emulsion-based heat-shielding property) having an aqueous two-component curability that combines a specific three kinds of polyols, cellulose nanofibers (CNF), and a reactive film-forming aid. It was confirmed that the thermal barrier pavement of the present invention by the coating composition) can provide workability and durability comparable to those of the MMA thermal barrier pavement conventionally applied to roadways.
In addition, even when cellulose nanofibers are not added, it is equivalent to the case where cellulose nanofibers are added, or at least better workability than thermal barrier pavement (conventional thermal barrier pavement) using a conventional general water-based paint. It was confirmed that durability was obtained.

  Furthermore, the main ingredient component in the heat-shielding coating composition of the present invention will be described in detail.

As a coating film forming binder component in the main agent, a polyol resin having a hydroxyl group is used so that aqueous two-component room temperature crosslinking is possible. As the polyol resin particles, single emulsion particles or dispersion particles are used. Rather than using emulsion particles as a main component, emulsion particles and dispersion particles having relatively small diameters and different particle characteristics are blended in relatively small amounts, and a total of three types of polyol resins are blended. . That is, in the main component of the heat-shielding coating composition of the present invention, the following three types of aqueous resin particles (A) to (C) are dispersed as a coating film-forming binder component in an aqueous medium.
(A): a hydroxyl group-containing room temperature cross-linked polymer emulsion polyol (B) containing a polyurethane having a hydrazine structure and a carbonyl group-containing acrylic polymer (B): a hydroxyl group-containing acrylic emulsion polyol (C): a hydroxyl group-containing polyurethane dispersion polyol

  Here, the water-based resin has three forms of a water-soluble type, a dispersion type, and an emulsion type. The general characteristics of each form of resin are as follows.

Appearance of the resin: The water-soluble type is roughly classified into transparent, the dispersion type is roughly translucent to milky white, and the emulsion type is roughly classified into milky white.
Particle size: The water-soluble type is roughly classified into 10 nm or less, the dispersion type is roughly classified into 10 nm to 100 nm, and the emulsion type is classified into 50 nm to 500 nm.
-Molecular weight: The water-soluble type is roughly classified into small (10 ³ to 10 ⁴ ), the dispersion type is medium (10 ³ to 10 ⁶ ), and the emulsion type is large (10 ³ or more).
・ Viscosity: The water-soluble type is roughly classified into high viscosity and correlated with the molecular weight, the dispersion type is moderately correlated with the molecular weight, and the emulsion type is roughly classified with low viscosity and not correlated with the molecular weight.
-Fluidity: Water-soluble type is broadly classified into Newtonian flow, dispersion type is thixotropic, and emulsion type is thixotropic.
・ Film-forming property: Water-soluble type forms a dense coating close to solvent-based resin, Dispersion type has intermediate properties between water-soluble type and emulsion type, and emulsion type forms a coating by particle fusion to make it dense It is roughly divided into lacking.
Water resistance: The water-soluble type is roughly classified into poor or good, the dispersion type is good, and the emulsion type is very good.

  Therefore, the hydroxyl group-containing room temperature cross-linked polymer emulsion polyol (A) and the hydroxyl group-containing acrylic emulsion polyol (B) used as a coating film forming binder component in the main component of the heat-shielding coating composition in the present invention are emulsion-type aqueous resins, Further, the hydroxyl group-containing polyurethane dispersion polyol (C) has the above-mentioned characteristics as a dispersion-type aqueous resin. The above classification is merely conceptual and does not limit the characteristics of each resin used in the present invention.

  The reason why the three types of aqueous resin particles (A), (B) and (C) are blended as the coating film forming binder component is as follows.

  That is, the hydroxyl group-containing room temperature cross-linked polymer emulsion polyol (A) contains a polyurethane having a hydrazine structure and a carbonyl group-containing acrylic polymer and exhibits self-crosslinkability, and at the same time, is crosslinked at room temperature by a urethane reaction (two-component curing). A water-based resin that can be used as a main component of the film-forming binder component to impart appropriate hardness to the film, ensuring durability and weather resistance of the film, and at the same time improving drying (quick drying) It is a necessary resin. Therefore, in this embodiment as well, it is used as a main component occupying 50% by weight or more (90% by weight or less) of the coating film forming binder component. However, when only relatively large-diameter emulsion particles are used as the resin for the coating film forming binder, the gaps between the particles become large and the coating film lacks the denseness, so that sufficient water resistance and adhesion are obtained. In addition, the flexibility of the coating film is reduced and the coating film becomes brittle, and the coating film is liable to be peeled off or damaged. Furthermore, since the hydroxyl group-containing room temperature cross-linked polymer emulsion polyol (A) alone requires a high boiling point solvent to form a film, it dissolves asphalt and has sufficient adhesion to the base (the surface of the paving substrate such as asphalt). is not.

  Therefore, in the present invention, a hydroxyl group-containing acrylic emulsion polyol (B) is used as a relatively small-sized emulsion particle in combination with a hydroxyl group-containing room temperature cross-linked polymer emulsion polyol (A) containing a polyurethane having a hydrazine structure and a carbonyl group-containing acrylic polymer. ), And a hydroxyl group-containing polyurethane dispersion polyol (C) as a dispersion particle having a smaller diameter to improve the denseness of the coating film, improve flexibility and eventually durability, and improve water resistance. Yes.

  Here, the particles of the resin (polyol) other than the main component hydroxyl group-containing room temperature cross-linked polymer emulsion polyol (A) have a smaller diameter than the hydroxyl group-containing acrylic emulsion polyol (A) which is the main component of the coating film forming binder component. Hydroxyl group-containing acrylic emulsion polyol (B) having different morphology and particle characteristics, and a hydroxyl group having a urethane skeleton different from the skeleton of hydroxyl group-containing acrylic emulsion polyol (A) as the main component, and having a small diameter and different particle form and particle characteristics The contained polyurethane dispersion polyol (C) is used.

  Thus, as a main resin, a combination of a hydroxyl group-containing room temperature cross-linked polymer emulsion polyol (A) as a main component and a hydroxyl group-containing acrylic emulsion polyol (B) and a hydroxyl group-containing polyurethane dispersion polyol (C). By adding a reactive film-forming aid that also serves as a curing agent to be described later to the main agent, it becomes possible to obtain a coating film excellent in coating film strength (durability), quick-drying property, and flexibility. It was.

  Here, the hydroxyl group-containing normal temperature occupying the entire coating film forming binder component (that is, the total amount of the hydroxyl group-containing acrylic emulsion polyol (A), the hydroxyl group-containing acrylic emulsion polyol (B), and the hydroxyl group-containing acrylic dispersion polyol (C)). The blending ratio of the crosslinked polymer emulsion polyol (A) is in the range of 50 to 90% by weight, the blending ratio of the hydroxyl group-containing polyurethane dispersion polyol (B) is in the range of 10 to 40% by weight, and the hydroxyl group-containing polyurethane dispersion polyol. The blending ratio of (C) is preferably in the range of 5 to 30% by weight.

  Moreover, the average particle diameter of the resin particles of each coating film forming binder component is that the average particle diameter and hydroxyl group content of the hydroxyl group-containing acrylic emulsion polyol (B) are more important than the average particle diameter of the hydroxyl group-containing room temperature cross-linked polymer emulsion polyol (A). The average particle size of the polyurethane dispersion polyol (C) may be small, but as a specific particle size, the average particle size of the hydroxyl group-containing acrylic emulsion polyol (A) is preferably about 130 to 230 nm. The average particle size of (B) is preferably about 90 to 140 nm, and the average particle size of the hydroxyl group-containing polyurethane dispersion polyol (C) is preferably about 40 to 90 nm.

  Details of these binder resin components (A), (B), and (C) will be further described.

<Hydroxyl-containing acrylic emulsion polyol (A)>
The hydroxyl group-containing acrylic emulsion polyol (A) is a main component of a coating film-forming binder component in an aqueous two-component room temperature crosslinking type heat-shielding coating composition, and contains a polyurethane having a hydrazine structure and a carbonyl group-containing acrylic polymer. Therefore, it exhibits a self-crosslinking property by ketimine reaction, and therefore self-crosslinks and cures early in the drying process after application as a water-based paint. At the same time, since this hydroxyl group-containing acrylic emulsion polyol (A) has a hydroxyl group (—OH), crosslinking (two-component curing) by urethane reaction can proceed at room temperature. Can sufficiently advance the crosslinking by the urethane reaction. As described above, the hydroxyl group-containing acrylic emulsion polyol (A) is an aqueous resin necessary for imparting hardness to the coating film to ensure strength and durability, and at the same time to improve the drying property (fast drying property). . As this hydroxyl group-containing acrylic emulsion polyol (A), it is desirable to use one having a hydroxyl value of 10 to 30 mg KOH / g and a glass transition temperature (Tg) of 25 to 45 ° C. Furthermore, the particle size of the hydroxyl group-containing room temperature cross-linked polymer emulsion polyol (A) is preferably within the range of 130 to 230 nm in terms of average particle size.

  Here, when the hydroxyl value of the hydroxyl group-containing acrylic emulsion polyol (A) is less than 10 mgKOH / g, weather resistance, water resistance and stain resistance cannot be obtained. On the other hand, when it exceeds 30 mgKOH / g, brittleness increases. On the other hand, when the glass transition temperature (Tg) is less than 25 ° C, the weather resistance, water resistance, and stain resistance are lowered. On the other hand, when it exceeds 45 ° C, the brittleness is increased. Furthermore, when the blending ratio of the hydroxyl group-containing acrylic emulsion polyol (A) in the entire coating film forming binder component is less than 50% by weight, the hardness of the coating film becomes insufficient and durability (weather resistance, water resistance, contamination resistance) If it exceeds 90% by weight, the brittleness increases.

<Hydroxyl group-containing acrylic emulsion polyol (B)>
Since the hydroxyl group-containing acrylic emulsion polyol also has a hydroxyl group (—OH), it is an aqueous resin capable of sufficiently proceeding with a crosslinking reaction (two-component curing) at room temperature by adding a reactive film-forming aid. In particular, it is an aqueous resin capable of sufficiently proceeding with crosslinking by urethane reaction by adding a reactive film-forming aid. Such a hydroxyl group-containing acrylic emulsion polyol (B) is mainly applied by combining with the hydroxyl group-containing room temperature cross-linked polymer emulsion polyol (A), which is the main component of the above-mentioned coating film forming binder, in a relatively small amount. It improves the strength (toughness) of the film and contributes to the improvement of the drying property (fast drying property). As this hydroxyl group-containing acrylic emulsion polyol (B), it is desirable to use those having a hydroxyl value of 50 to 70 mg KOH / g and a glass transition temperature (Tg) of 30 to 50 ° C. Furthermore, the particle size of the hydroxyl group-containing acrylic emulsion polyol (B) is preferably in the range of 90 to 140 nm in terms of average particle size.

  When the hydroxyl value of the hydroxyl group-containing acrylic emulsion polyol (B) to be used is less than 50 mgKOH / g, the weather resistance, water resistance and stain resistance are lowered. On the other hand, when it exceeds 70 mgKOH / g, the brittleness is increased. Further, when the glass transition temperature (Tg) of the hydroxyl group-containing acrylic emulsion polyol (B) used is less than 30 ° C., the weather resistance, water resistance and stain resistance are lowered, while when it exceeds 50 ° C., the brittleness is increased. Furthermore, when the blending ratio of the hydroxyl group-containing acrylic emulsion polyol (B) in the entire coating film forming binder component is less than 10% by weight, the weather resistance, water resistance and stain resistance are reduced. growing.

  In addition, as a particle | grains of a hydroxyl-containing acrylic emulsion polyol (B), you may use what has what is called a core shell structure. For example, hydroxyl-containing acrylic emulsion polyol particles having different properties between the core and the shell may be used so that the core portion is hard and the shell portion is soft. Specifically, for example, particles in which the molecular weight or hydroxyl value of the hydroxyl group-containing acrylic emulsion polyol is different between the core and the shell can be used. However, it is needless to say that the invention is not limited to the one having such a core-shell structure.

<Hydroxyl-containing polyurethane dispersion polyol (C)>
The hydroxyl group-containing polyurethane dispersion polyol is also an aqueous resin that can be cured in two liquids by a urethane reaction at room temperature, and is relatively combined with the hydroxyl group-containing room temperature cross-linked polymer emulsion polyol (A) that is the main component of the above-mentioned coating film forming binder. Mixing a small amount is effective in improving toughness and flexibility. Here, since the hydroxyl group-containing polyurethane dispersion polyol (C) contains urethane in its skeleton itself, the reactive film-forming aid is cured even in a relatively small amount. It is possible to reduce flexibility and maintain flexibility. The hydroxyl group-containing polyurethane dispersion polyol (C) used here preferably has a hydroxyl value in the range of 40 to 60 mgKOH / g and a glass transition temperature (Tg) in the range of -30 to -10 ° C. Furthermore, the particle size of the hydroxyl group-containing polyurethane dispersion polyol (C) is preferably in the range of 40 to 90 nm in terms of average particle size.

  When the hydroxyl value of the hydroxyl group-containing polyurethane dispersion polyol (C) to be used is less than 40 mgKOH / g, the weather resistance, water resistance and stain resistance are lowered. On the other hand, when it exceeds 60 mgKOH / g, the brittleness is increased. Further, when the glass transition temperature (Tg) of the hydroxyl group-containing polyurethane dispersion polyol (C) used is less than −30 ° C., the weather resistance, water resistance, and stain resistance are lowered, while when it exceeds −10 ° C., the brittleness is reduced. growing. Furthermore, when the blending ratio of the hydroxyl group-containing polyurethane dispersion (C) in the entire coating film forming binder component is less than 5% by weight, the flexibility of the coating film is decreased, and when it exceeds 30% by weight, the drying property and toughness are decreased. To do.

  Furthermore, the main component of the heat-shielding coating composition according to the embodiment of the present invention contains a colored pigment, preferably a heat-shielding colored pigment, in addition to the above-described coating film-forming binder components (A), (B), and (C). Furthermore, it is desirable to contain cellulose nanofiber (CNF) as a coating film strength improver.

  Next, each component other than the above binder resin component in the main agent will be described.

<Cellulose nanofiber (CNF)>
Cellulose nanofiber (CNF) is a biomass material made by refining plant fibers such as wood fibers (pulp) to the nano-order, and is entangled in the coating film and presents in a mesh shape, thereby improving the strength of the coating film, especially the resistance to resistance. It is effective for improving the durability of the thermal barrier coating film by improving the peelability and wear resistance. At the same time, the water-soluble fiber has good water wettability and can be uniformly dispersed in the water-based paint, and is advantageous in terms of strength over many other water-soluble fibers.

  As described above, it is newly found by experiments of the present inventors that inclusion of cellulose nanofibers derived from plant fibers is effective in improving the strength and durability of the thermal barrier coating. . That is, in the coating composition of the present invention, in addition to the effect of improving the coating film strength by the blending of the three types of pollen as described above, the addition of cellulose nanofibers makes the coating film strength and durability more remarkable. As a result, it was possible to apply it even on roadways.

  In addition, the size of the cellulose nanofiber to be used is not particularly limited, and the definition as an industry is not completely fixed, but usually the fiber length is 1 to 100 μm and the fiber diameter is 1 to 1000 nm. That's fine. However, when actually blending into a paint as a coating film component, it is easy to use cellulose nanofibers that are in the form of powder aggregated to about several tens to several hundreds of micrometers.

  Here, the ratio of the cellulose nanofibers to the whole main agent is preferably within the range of 0.01 to 10.0% by weight, and within that range is preferably within the range of 0.2 to 3.0% by weight. It is. If the ratio of cellulose nanofibers is less than 0.2% by weight, particularly less than 0.01% by weight, there is a possibility that sufficient strength improvement effect and durability improvement effect due to addition of cellulose nanofibers cannot be obtained. On the other hand, if the ratio of cellulose nanofibers exceeds 3.0% by weight, particularly exceeding 10.0% by weight, there is a concern that the viscosity in the state of water-based paint becomes too high and the coating workability is lowered. The

<Colored pigment>
As the colored pigment, it is desirable to use a heat-shielding colored pigment. If a heat-shielding colored pigment is used as the colored pigment, the pigment also functions as a heat-shielding filler. That is, if a heat-shielding colored pigment is used, it is possible to ensure heat-shielding properties without adding a separate heat-shielding filler (or by reducing the amount of heat-shielding filler added separately). As the heat-shielding colored pigment, it is preferable to use titanium oxide having excellent heat-shielding properties. In addition to titanium oxide, iron oxide that exhibits heat-shielding properties by hue (for example, red iron oxide, yellow iron oxide, etc.), and other complex oxides System pigments and the like can be used. As a heat-shielding colored pigment typified by titanium oxide, the particle diameter is larger than that of general titanium oxide powder (average is about 0.2 μm), and the effect of reflecting near infrared rays in sunlight is great. It is preferable to use a heat-shielding colored pigment such as a large-particle heat-shielding colored pigment, for example, a large-particle-size titanium oxide having an average particle diameter of 0.5 to 2.0 μm. If the average particle diameter of the heat-shielding colored pigment such as titanium oxide is less than 0.5 μm, the effect of reflecting the near infrared rays and improving the heat-shielding property cannot be obtained sufficiently, while if it exceeds 2.0 μm, the weather resistance and water resistance Sexuality decreases.

  Here, if the blending amount of the heat-shielding colored pigment with respect to the coating composition excluding the aggregate is less than 5% by weight, the effect of improving the heat-shielding property by the heat-shielding colored pigment is not sufficiently exhibited, whereas it exceeds 25% by weight. For example, since weather resistance, water resistance, and adhesion are lowered, the blending ratio of the heat-shielding colored pigment is preferably in the range of 5 to 25% by weight.

<Other main ingredients>
Furthermore, the main agent may contain aggregates such as silica sand and ceramic powder as necessary as an anti-slip material for the surface of the top coat thermal barrier layer. The aggregate as an anti-slip material preferably has an average particle size of about 0.053 to 1.5 mm, and the amount may be, for example, about 50 to 70% by weight with respect to the weight of the coating composition.

  Further, in some cases, a viscosity adjusting agent may be included. In other words, when the amount of cellulose nanofiber is small or when an aggregate such as an anti-slip material is blended, if the viscosity of the aqueous coating is too low, these may settle, and the viscosity of the coating is reduced there. In order to increase the viscosity to some extent, a viscosity modifier may be added. As the viscosity modifier in this case, for example, a solution-type additive using a water-soluble polymer mainly composed of methacrylic acid can be used.

  In addition, as with general water-based paints, of course, extender pigments, anti-settling agents, wetting and dispersing agents, antifoaming agents, leveling agents, preservatives, antifungal agents and the like may be blended as necessary. is there.

  The main component in the heat-shielding coating composition of the present invention is dispersed in an aqueous medium such as water, and immediately before coating on a paving surface such as asphalt as a base, a reactive film-forming auxiliary agent that also serves as a curing agent is added and mixed. To do.

  This reactive film-forming aid is for enabling two-component curing with the resin particles of the binder component in the main agent dispersed in an aqueous medium as an aqueous paint. As this type of film-forming auxiliary, a high-boiling solvent that assists in the film formation of water-based paint emulsion particles has been generally used. However, when a high-boiling solvent is used, the solvent component is contained in the coating film. In many cases, there are harmful effects. For example, an unnecessary resin film is formed between the underlying paved surface and the coating film, and the bonding force is lost, or the solvent component remains in the coating film, causing the coating film to cohesive.

  Therefore, as the reactive film-forming aid in the present invention, the substance itself is also a polymer, and the binder component is a hydroxyl group-containing room temperature cross-linked polymer emulsion polyol (A), a hydroxyl group-containing acrylic emulsion polyol (B), a hydroxyl group-containing polyurethane disperser. A substance that can be cured (crosslinked) by reacting with John polyol (C) is used. Specifically, a polyisocyanate resin containing an isocyanate group (—NCO) that causes a urethane crosslinking reaction with the hydroxyl group (—OH) of each polyol is used as a reactive auxiliary agent. As a specific polyisocyanate-based resin, a resin having a water-dispersible isocyanurate ring is preferably used.

And just before coating on the paving surface such as asphalt as a water-based paint, polyisocyanate is added to the main agent as a reactive film-forming aid, and if applied immediately, the isocyanate group (-NCO) in the coating film A urethane bond is generated by cross-linking with the hydroxyl group (—OH) of each polyol of the main component binder component, and each polyol resin particle is bonded through the reactive film-forming aid, and the coating film is cured (film-forming). ) Will be.
Since such a polyisocyanate itself is a polymer, an unnecessary resin film is formed between the surface of the underlying asphalt pavement or the like and the coating film, resulting in a loss of bonding force or a solvent in the coating film. The components do not remain and cohesive failure of the coating film does not occur, and there is little possibility of adversely affecting water resistance or the like when the film is formed.

  The molar ratio of the isocyanate group (—NCO) of the polyisocyanate that is a reactive film-forming aid to the hydroxyl group (—OH) of each polyol that is the binder component of the main component is preferably 0.8 to 1.1, and this molar ratio. If it is less than 0.8, the proportion of uncrosslinked polyol increases, and the adhesion and flexibility decrease, and if the molar ratio exceeds 1.1, the weather resistance, water resistance and stain resistance decrease.

  In addition to the above-mentioned heat-shielding colored pigments, each colored pigment may be added as a pigment in order to exhibit colored colors such as green, blue, yellow, and red. The blending ratio of these pigments in that case may be determined as necessary and is not particularly limited, but is usually about 0.1 to 10% by weight with respect to the coating composition excluding the aggregate. That's fine.

  An example of the construction method of the heat-shielding pavement using the coating composition of this invention is as follows. However, the construction method described below is merely an example until it gets tired, and it is needless to say that the construction method is not limited to the following method.

First, the paint composition of the present invention is removed from dirt, dust, oil, etc. adhering to a pavement surface (road surface) to be constructed, for example, an asphalt pavement surface, and cured with a masking tape as necessary.
Next, the main component of the coating composition of the present invention and the reactive auxiliary agent are prepared in a predetermined weight ratio, water is added as an aqueous medium, and the mixture is sufficiently stirred using a mixing means such as a hand mixer. Use paint. If necessary, non-slip aggregates such as silica sand may be added to the water-based paint as described above.

Then, a first spraying operation of spraying this water-based paint onto the asphalt pavement surface is performed using a lysine spray gun by an air coating device. Although spraying of the aqueous coating composition is not particularly limited in this case, in the adhesion amount of the coating composition, 0.5~0.7kg / ^{m 2} about, for example, it may be set to 0.6 kg / ^{m 2} approximately. If the application amount of the water-based paint is less than 0.5 kg / m ² , the dispersion is too small and uneven dispersion occurs, and if it exceeds 0.7 kg / m ² , it is excessive and uneconomical and the drying property is remarkably lowered. After confirming that the sprayed water-based paint has dried, the second spraying operation is performed in the same manner as the first. In place of the spraying operation, painting may be performed using a free broom, a rubber rake, a roller brush or the like.
Further, if necessary, a primer layer may be formed on a base material pavement surface such as an asphalt pavement surface by coating, and then the above water-based paint may be sprayed on the surface of the primer layer.
Then, after removing the masking tape and confirming that the sprayed water-based paint is sufficiently dried (cured), the traffic may be opened. The drying time is usually about 15 minutes to 2 hours at room temperature.

  Here, in the drying process after application of the aqueous paint, the hydroxyl group-containing room temperature cross-linked polymer emulsion polyol (A) containing a polyurethane having a hydrazine structure and a carbonyl group-containing acrylic polymer is self-crosslinked early. In addition, from the drying process to after drying, the presence of a reactive film-forming auxiliary agent that also serves as a curing agent, acid group-containing room temperature cross-linked polymer emulsion polyol (A), hydroxyl group-containing acrylic emulsion polyol (B), hydroxyl group-containing, which are binder components The polyurethane dispersion polyol (C) is cross-linked by the urethane reaction, and film formation proceeds.

  As pavements suitable for the heat-shielding pavement of the present invention, there are asphalt pavement surfaces, concrete pavement surfaces, and other asphalt elastic pavements blended with rubber particles and cork particles, which are particularly effective for pavement surfaces of roadways. .

In addition, the heat-shielding pavement of the present invention is constructed by coating the heat-shielding coating composition of the present invention on a new or existing pavement surface. This pavement can be applied to roads regardless of roads and sidewalks, and can also be applied to various outdoor facilities.
And by applying the heat-shielding pavement of this invention to a road etc., the heat storage of a pavement can be prevented and the temperature rise of a road surface can be suppressed. In addition, the thermal environment of pedestrians is improved, which is effective as a summer heat stroke countermeasure. Furthermore, since it is a water-based paint, there are few adverse effects on people and the environment, and there is little odor during construction, which is advantageous in terms of environmental hygiene and safety.

  Examples of the present invention will be described below together with comparative examples. The following examples are for explaining the effects of the present invention, and it goes without saying that the configurations, processes, and conditions described in the examples do not limit the technical scope of the present invention.

  No. in the upper part of Table 5. 1-No. Since various tests and evaluations were performed on coating films using water-based paint compositions having various blends as shown in Table 11, the results are shown in the lower part of Table 5. In addition, about the mixing | blending of the upper stage of Table 5, the display is abbreviate | omitted about a colored pigment and an aggregate.

  Explaining the specific examples, polyurethane having a hydrazine structure having a hydroxyl value of 20 mgKOH / g, a glass transition temperature (Tg) of 35 ° C., and an average particle size of 180 nm and a carbonyl group-containing acrylic as a coating film forming binder component Resin of hydroxyl group-containing room temperature cross-linked polymer emulsion polyol (A) containing a polymer and a hydroxyl group-containing acrylic emulsion polyol having a hydroxyl value of 60 mgKOH / g, a glass transition temperature (Tg) of 40 ° C., and an average particle size of 40 nm ( B) resin and a hydroxyl group-containing polyurethane dispersion polyol (C) resin having a hydroxyl value of 50 mgKOH / g, a glass transition temperature (Tg) of −20 ° C. and an average particle diameter of 60 nm were prepared.

Furthermore, as a coating film reinforcing agent, a CNF aqueous dispersion (hereinafter referred to as “CNF (I)) in which cellulose nanofibers (CNF) having a fiber length of 100 μm or less and a fiber thickness of 50 to 1000 μm are dispersed in pure water at a concentration of 2% by weight. ) "). In addition, a powder (hereinafter referred to as “CNF (II)”) having a diameter of about several tens to several hundreds μm of cellulose nanofiber (CNF) aggregates of the same size was prepared.
In addition, as a coating film reinforcing agent for comparison, carboxymethyl cellulose (CMC) having a fiber length of 1 mm or less and a fiber width of 20 to 30 μm, and a fiber length of 1 mm or less and a fiber width of 20 to 30 μm, which are general water-soluble celluloses. Hydroxyethyl cellulose (HEC) was prepared.

  On the other hand, a polyisocyanate having a water-dispersible isocyanurate ring was prepared as a reactive film-forming aid that also served as a curing agent.

  Further, titanium oxide having an average particle diameter of 1.0 μm and a composite oxide having an average particle diameter of 1.1 μm were prepared as a heat-shielding colored pigment that also served as a heat-shielding filler. Further, silica sand having an average particle size of 0.08 to 0.8 mm was prepared as an aggregate as an anti-slip material. Furthermore, a solution-type additive using a water-soluble polymer mainly composed of methacrylic acid was prepared as a viscosity modifier.

The three polyols (A), (B), and (C) described above were blended as follows to obtain a coating film forming binder component. In addition, each compounding quantity (weight%) is a ratio with respect to a total coating-film formation binder component.
-Hydroxyl-containing room temperature cross-linked polymer emulsion polyol (A): 60% by weight
・ Hydroxyl group-containing acrylic emulsion polyol (B): 30% by weight
・ Hydroxyl-containing polyurethane dispersion polyol (C): 10% by weight

While adding a viscosity modifier to the coating film forming binder component formulated as described above, 4.5% by weight of titanium oxide as a heat-shielding colored pigment, 0.5% of composite oxide, and as an anti-slip material As an aggregate, 58.0% by weight of silica sand was added as a main agent. Further, the reactive film-forming aid was added to and mixed with the main agent, and then immediately sprayed onto the surface of the dense asphalt according to a conventional method. The coating amount was 600 g / m ² twice (average coating thickness of about 500 to 600 μm). After painting, leave at room temperature for 72 hours. A blank product indicated as 1 (no CNF added) was obtained.

  Moreover, in order to confirm the effect of CNF addition, no. No. 1 in Table 5 was prepared by adding CNF (I) or CNF (II) in various proportions to the base material of No. 1 blank product (without addition of CNF). 4-No. 10 was added with CNF. The viscosity modifier is No. 1 with a CNF addition amount of 1%. No. 7 is reduced to 1%, and the amount of CNF added is 2% or more. In 8-10, it was not added. The composition of other CNF-added products is No. 1 is the same as the blank product.

For further comparison, the above-mentioned carboxymethyl cellulose (CMC) or hydroxyethyl cellulose (HEC), which is a general water-soluble cellulose, is No. No. 1 in Table 5 was added to the main product of the blank product of No. 1 (without CNF addition). 2, No. The comparative product shown in FIG.
In addition, a conventional product obtained by spraying a conventional general water-based paint on the surface of dense asphalt according to a conventional method is No. It was set to 11. Here, the conventional general water-based paint is an acrylic emulsion type one-component heat-shielding paint conventionally used for sidewalks, and its specific composition and application conditions are as follows.
Titanium oxide: 10% by weight, organic black pigment: 1% by weight, calcium carbonate: 10% by weight, acrylic emulsion resin component: 15% by weight, silica sand: 33% by weight, other water and additives: 31% were mixed. The product was a water-based thermal barrier paint. As a coating condition, a sample coated 500 g / m ² × 2 times was used as a comparative body.

No. 1-No. Since various measurements or evaluation tests were performed on each of the 11 coated products, the results are shown in the lower part of Table 5.
The contents of each measurement and evaluation test are as follows.

-Viscosity measurement: Measured by the Stormer viscosity measurement method of JISK5600-2-2.
・ Dryness evaluation: Finger touch evaluation (measurement of the time until the paint does not adhere when touched with a finger), tack free evaluation (steps on shoes, marks are left) (Measurement of time until no longer remains).
-Impact resistance evaluation: Painted on dense asphalt, and after 7 days of curing, the peeled state when a weight of 3 kg weight was dropped from a height of 1 m was observed.
-Rubber ring torsion test: A tester rides on a solid tire and observes the peeled state when the work is twisted at 90 °.

Here, the impact resistance and the rubber ring torsion test were evaluated as follows according to the peeled state.
○: No peeling.
○ △: Aggregate is slightly exposed at the convex portion of the surface.
Δ: 5 or less small peels having a diameter of about 5 mm or less are recognized per 20 cm ² .
X: Medium peeling (about 1 cm in diameter) is observed.
XX: Large peeling (diameter of about 2 cm or more) is observed.
XXX: More than 1/2 of the total area is largely peeled off.

  From the results shown in Table 5, it can be seen that when the coating composition of the present invention is used, a coating film having good characteristics can be obtained regardless of the presence or absence of CNF addition. In addition, when CMC or HEC is added as cellulose, the viscosity as a coating becomes too large, and the coating work is actually difficult. On the other hand, with the CNF-added product, the increase in viscosity is small and the coating workability is impaired. It turns out that there are few things. In addition, from the result of Table 5, when adding CNF, it turns out that the addition amount of CNF is 0.2 to 3.0%.

  Furthermore, in order to investigate the abrasion resistance of the coating film by the water-based coating composition, No. No. 1 blank product (product of the present invention: no CNF added) and product No. 1 of the present invention to which CNF was added. A Taber abrasion resistance test was conducted on the 8 CNF 2.0% added product. For comparison, a Taber abrasion resistance test was also performed on a conventional general water-based paint (No. 11). Here, the Taber abrasion resistance test was conducted in accordance with the abrasion resistance (wear wheel method) of JIS K5600-5-9. The results are shown in Table 6.

  From Table 6, it can be seen that the wear resistance is improved by adding CNF.

  Furthermore, the drying property (fast drying property) of the coating film in the water-based coating composition was examined. No. Table 7 shows the results of dryness evaluation for the blank product No. 1 (without addition of CNF). Table 8 shows the dryness evaluation results for the 2.0% CNF-added product. Table 9 shows the results of dryness evaluation in the case of 11 conventional general water-based paints. In addition, dryness is evaluated by finger touch in various environments (time until the paint does not adhere when touched with a finger) and tack-free evaluation (time until no marks remain after stepping on shoes) ).

  As is clear from comparison of Tables 7 to 9, in the products of the present invention, both the CNF-free product and the CNF-added product are not suitable for the low-temperature region, which has conventionally been regarded as inappropriate due to poor drying properties as a water-based paint. It can be seen that a good drying property can be obtained with the CNF-added product even in a humid region.

  Furthermore, since the cut-off resistance and the water cut-off resistance by an actual vehicle outdoors were examined, the results are shown in Table 10. As a test method, two adults got on the light van, made 10 reciprocations of the maximum movable region of the handle, and examined the peeling state of the coating film. In Table 10, the upper “cut-off resistance” indicates the result of testing with a dried coating film, and the lower “water-cut resistance” indicates the result of testing with a sprayed coating film.

  From Table 10, it can be seen that in the present invention product, both the CNF-free product and the CNF-added product are excellent in both wear resistance and water wear resistance.

DESCRIPTION OF SYMBOLS 1 ... Pavement base material 3 ... Heat-shielding coating film 31 ... Coating-film matrix 32 ... Cellulose nanofiber 33 ... Inorganic heat-shielding colored pigment

Claims (13)

Hydroxyl group-containing room temperature cross-linked polymer emulsion polyol (A) containing polyurethane having a hydrazine structure and a carbonyl group-containing acrylic polymer as particles of a film-forming binder component dispersed in an aqueous medium, and a hydroxyl group-containing acrylic emulsion polyol A main agent containing (B) and a hydroxyl group-containing polyurethane dispersion polyol (C) and containing a colored pigment;
A reactive film-forming auxiliary agent that also serves as a curing agent, comprising a polymer that causes a crosslinking reaction with the film-forming binder component of the main agent to cure the coating film;
A thermal barrier coating composition having aqueous two-component curability, comprising: In the heat-shielding coating composition having aqueous two-component curability according to claim 1,
A thermal barrier coating composition having aqueous two-component curability, wherein the main agent contains cellulose nanofibers as a coating strength improver. In the heat-shielding coating composition having aqueous two-component curability according to claim 2,
A heat-shielding coating composition having aqueous two-component curability, characterized in that the ratio of cellulose nanofibers to the whole main ingredient is in the range of 0.01 to 10.0% by weight. In the heat-shielding coating composition having aqueous two-component curability according to any one of claims 1 to 3,
The blending ratio of the hydroxyl group-containing room temperature cross-linked polymer emulsion polyol (A) in the entire coating film forming binder component is in the range of 50 to 90% by weight, and the blending ratio of the hydroxyl group-containing acrylic emulsion polyol (B) is 10 to 40. A thermal barrier coating composition having aqueous two-component curability, wherein the blending ratio of the hydroxyl group-containing urethane dispersion polyol (C) is in the range of 5 to 30% by weight within the range of% by weight. In the heat-shielding coating composition having aqueous two-component curability according to any one of claims 1 to 4,
The hydroxyl group-containing room temperature cross-linked polymer emulsion polyol (A) has a hydroxyl value of 10 to 30 mg KOH / g and a glass transition temperature (Tg) of 25 to 45 ° C.,
The hydroxyl group-containing acrylic emulsion polyol (B) has a hydroxyl value of 50 to 70 mg KOH / g and a glass transition temperature (Tg) of 30 to 50 ° C.,
The hydroxyl group-containing urethane dispersion polyol (C) has a hydroxyl value of 40 to 60 mg KOH / g and a glass transition temperature (Tg) in the range of -30 to -10 ° C. Heat-shielding coating composition having properties. In the heat-shielding coating composition having aqueous two-component curability according to any one of claims 1 to 5,
A thermal barrier coating composition having aqueous two-component curability, wherein the colored pigment is a thermal barrier colored pigment having an average particle diameter in the range of 0.5 to 2.0 μm. In the heat-shielding coating composition having aqueous two-component curability according to claim 6,
The heat-shielding coating composition having aqueous two-component curability, wherein the heat-shielding colored pigment is at least one selected from titanium oxide, iron oxide, and complex oxide pigments. In the heat-shielding coating composition having aqueous two-component curability according to any one of claims 1 to 7,
A thermal barrier coating composition having aqueous two-component curability, wherein the reactive film-forming aid also serving as a curing agent comprises a polyisocyanate. In the heat-shielding coating composition having aqueous two-component curability according to claim 8,
The blending ratio of the reactive film-forming aid composed of polyisocyanate and the film-forming binder component in the main agent is such that the molar ratio of the isocyanate group of the reactive film-forming aid to the hydroxyl group of the polyol in the film-forming binder component. A thermal barrier coating composition having aqueous two-component curability, characterized in that it is in the range of 0.8 to 1.1. The main agent and the reactive film-forming aid in the heat-shielding coating composition according to any one of claims 1 to 9 are kneaded to form a water-based paint, and the water-based paint is formed on a pavement substrate. A heat-shielding paint painting method characterized by painting on the surface. A heat-shielding pavement in which a heat-shielding coating film is formed on the surface of the pavement substrate,
The thermal barrier pavement is
Hydroxyl group-containing room temperature cross-linked polymer emulsion polyol (A) containing a hydrazine structure polyurethane and a carbonyl group-containing acrylic polymer, a hydroxyl group-containing acrylic emulsion polyol (B), and a hydroxyl group-containing polyurethane disper as coating film forming binder components A main agent containing John polyol (C) and a colored pigment;
A reactive film-forming auxiliary agent that also serves as a curing agent, comprising a polymer that causes a crosslinking reaction with the film-forming binder component of the main agent to cure the coating film;
Consists of
A heat-shielding pavement, wherein each polyol and a reactive film-forming aid are cross-linked. In the heat-shielding pavement according to claim 11,
The main agent contains cellulose nanofiber as a coating film strength improver, The heat-shielding pavement characterized by the above-mentioned. In the heat-shielding pavement according to any one of claims 11 and 12,
The heat-shielding pavement, wherein the pavement base material is asphalt, concrete, or rubber chip urethane.

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