Method for applying road marking paint and water-based primer for road marking

Abstract

To provide a coating method of a coating for a road sign which is an aqueous primer that facilitates handling and has a small content of a volatile organic solvent, causes no spouting and swelling even after heating and drying after coating, can shorten its dry time, and has sufficient adhesion to a coating for a road sign, and an aqueous primer for a road sign used in the same.SOLUTION: An aqueous primer for a road sign that causes no spouting and swelling even after heating and drying after coating, can shorten its dry time, has sufficient adhesion to a coating for a road sign, facilitates handling and has a small content of a volatile organic solvent is produced by coating an aqueous primer for a road sign which is obtained by adding a heat-sensitive gelatinizer to synthetic resin emulsion and has a gelation temperature controlled to 100°C or lower onto a road surface, and then coating a coating for a road sign.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to a method for applying a road marking paint for marking roads and other road surfaces, and to an aqueous road marking primer used in the method. [Background technology]

[0002] BACKGROUND ART Conventionally, when a paint or coating material is applied to an object to be painted, a primer is used before the paint is applied in order to improve adhesion between the object to be painted and the paint film. This improves the adhesion between the object to be painted and the coating film, reduces peeling, swelling, cracking, etc. of the coating film, and improves the durability of the coating film.

[0003] This primer is also sometimes used when applying road marking paint to mark road surfaces such as road lanes and stop lines. Solvent-based primers are often used for this purpose due to their adhesiveness and drying properties. Many of these solvent-based primers use organic solvents with relatively low boiling points of 100°C or less, such as toluene or ethyl acetate.

[0004] This solvent-based primer strengthens the surface of asphalt pavement surfaces, concrete pavement surfaces, and existing road marking materials on these surfaces, forming a coating on these surfaces that has good adhesion to road marking paint, thereby improving adhesion. In recent years, water-based primers using synthetic resin emulsions as binders have been used in place of primers using organic solvents.

[0005] This is because primers that use organic solvents require a reduction in the amount of volatile organic solvents due to their impact on the environment, and because low-boiling organic solvents such as toluene and ethyl acetate contained in primers are flammable, so care must be taken not only when handling them but also when storing them. This water-based primer is made by adding tackifiers to a synthetic resin emulsion to improve adhesion between the road surface and the road marking material, making it easy to handle and containing a low amount of volatile organic solvents. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-183122

[0007] Patent Document 1 describes a water-based primer paint for road markings that contains a synthetic rubber emulsion and an emulsion-type tackifier in which the resin component constituting the solid component has a softening point, wherein the sum of the content of the solid component of the synthetic rubber emulsion and the content of the solid component of the emulsion-type tackifier is 10% by mass or more and 50% by mass or less of all components, and the content of the solid component of the emulsion-type tackifier relative to the content of the solid component of the synthetic rubber emulsion is 0.2 times or more and 1.5 times or less in mass ratio.

[0008] As a result, it is easy to handle, contains a small amount of volatile organic solvents, and is highly effective as an undercoat paint, yet requires a relatively short drying time. Summary of the Invention [Problem to be solved by the invention]

[0009] However, the water-based primer paint for road markings in Patent Document 1 is mainly composed of two types of synthetic rubber emulsions, and therefore dries more slowly than solvent-based primers. This means that traffic is blocked for a longer period while the primer is being applied, making it difficult to reduce the time required for marking construction.

[0010] The present disclosure aims to provide a method for applying a road marking paint that is easy to handle and has a low content of volatile organic solvents, does not cause swelling or blistering even when heated and dried after application, can shorten the drying time, and has sufficient adhesion to the road marking paint, and to provide an aqueous primer for road markings used therein. [Means for solving the problem]

[0011] After applying a water-based primer for road markings, which is made by adding a heat-sensitive gelling agent to a synthetic resin emulsion and adjusting the gelling temperature to below 100°C, A water-based thermosensitive gel type in which a thermosensitive gelling agent is added to a synthetic resin emulsion and the gelling temperature is adjusted to a temperature below 100°C. The application of road marking paint. As a result, the water-based primer for road markings is easy to handle and contains a small amount of volatile organic solvents, and does not swell or blister even when heated and dried after application, allowing the drying time to be shortened, and has sufficient adhesion to road marking paint.

[0012] After applying the water-based primer for road markings, the primer is heated to form a gelled film, and then: The water-based thermosensitive gel type The application of road marking paint. This prevents the water-based primer from bubbling up or the coating from swelling, allowing the road marking paint to dry quickly and be applied, thereby shortening the marking work period. After applying the water-based primer for road markings, The water-based heat-sensitive gel type road marking paint is applied and heated to form a gelled film. That is the thing. As a result, There is no swelling or swelling of the coating, and drying time can be shortened. Marking work can be shortened.

[0013] After the water-based primer for road marking has been applied, a melting type paint for road marking having a melting temperature in the range of 100 to 250°C is applied in a melted state. This allows the heat of the road marking paint to be used to gel the water-based road marking primer, and at the same time, the melt-type road marking paint is applied, thereby further shortening the marking application time.

[0014] The water-based primer for road markings is a synthetic resin emulsion to which a heat-sensitive gelling agent has been added, and the water-based primer for road markings is adhesive after drying. This improves the adhesion between the coating film formed by the water-based road marking primer and the road marking paint.

[0015] It is a water-based primer for road markings, made by adding a heat-sensitive gelling agent to a synthetic resin emulsion containing a high-boiling point solvent with a boiling point of 100°C or higher. This increases the adhesiveness of the coating film formed by the water-based primer for road markings, further improving the adhesion of the road marking paint. DETAILED DESCRIPTION OF THE INVENTION

[0016] The embodiments of the present disclosure will now be described in detail. The present disclosure relates to a method of applying a water-based primer for road markings to a road surface, which is made by adding a heat-sensitive gelling agent to a synthetic resin emulsion and adjusting the gelling temperature to a temperature lower than 100°C, and then applying a road marking paint.

[0017] The road surface is the surface of a road paved with asphalt or concrete, and is the part on which vehicles and pedestrians pass. Therefore, various markings such as lanes and stop lines are required. First, this water-based primer for road markings is intended to improve adhesion to road marking paint, which is used to mark lane markings, stop lines and other traffic signs, crosswalk signs, and other markings on road surfaces.

[0018] Typical road marking paints are those specified in JIS K 5665, and include water-based and solvent-based liquid paints and melt-type powder paints. Before applying this road marking paint, a water-based road marking primer is applied, which is made by adding a heat-sensitive gelling agent to a synthetic resin emulsion and adjusting the gelling temperature to below 100°C.

[0019] This synthetic resin emulsion is a dispersion of synthetic resin in water, and the synthetic resin used can be a homopolymer or copolymer of resins such as acrylic resin, urethane resin, vinyl chloride resin, silicone resin, vinyl acetate resin, polyester resin, styrene resin, and fluororesin. The synthetic resin emulsion may be a general type that can be produced by a conventional polymerization technique such as emulsion polymerization, and from the viewpoints of paint suitability, coating film properties, and ease of availability, acrylic synthetic resin emulsions and acrylic-styrene synthetic resin emulsions produced from acrylic resin and styrene resin are preferred.

[0020] A water-based primer for road markings can be prepared by adding a heat-sensitive gelling agent to this synthetic resin emulsion. By incorporating this heat-sensitive gelling agent, a gelled film is formed when the applied water-based primer for road markings in a wet state is heated, and when it dries, it becomes a primer coating film. This water-based primer for road markings containing a heat-sensitive gelling agent is a stable liquid at room temperature, but when it reaches the adjusted gelling temperature, the spaces between the synthetic resin particles, which are the main component of the water-based primer for road markings, become narrower, causing them to stick together and resulting in the loss of fluidity of the paint.

[0021] The gelled film formed by the gelation of the water-based primer for road markings in this way contains moisture, but as the synthetic resin gels, the components dispersed in the synthetic resin emulsion are combined and fixed. The gelling temperature of this heat-sensitive gelling agent can be adjusted by the type of synthetic resin emulsion, the type of heat-sensitive gelling agent, and the amount added. The gelling temperature of this water-based primer for road markings is adjusted to be higher than the ambient temperature but not exceeding 100°C.

[0022] If the temperature is below this range, the water-based primer for road markings will gel before application, making it impossible to apply. If the temperature is above 100°C, water vapor will be generated before gelation when heated, and this water vapor may cause the primer to swell and form a gelled film. There are no particular limitations on the thermosensitive gelling agent, as long as the resulting gelled film remains in a gel state even when the temperature drops to the same as the ambient temperature; both organic and inorganic gelling agents can be used, and once gelled, the agent does not return to its original fluid state.

[0023] Examples of organic thermosensitive gelling agents include starch and its derivatives, and nonionic surfactants such as alkylene oxide adducts of organopolysiloxane, alkylphenol-formalin condensates of organopolysiloxane, alkylene oxide adducts of alkylphenol-formalin condensates, polyvinyl methyl ether, and organopolysiloxane polyether copolymers.

[0024] Examples of inorganic heat-sensitive gelling agents include an aqueous ammonia solution of a zinc compound in which a zinc compound is dissolved in ammonia water, ammonium nitrate, ammonium chloride, sodium carbonate, potassium carbonate, sodium sulfate, potassium chloride, calcium chloride, calcium sulfate, magnesium sulfate, zinc ammonium complex salts, sodium nitrate, lead nitrate, and sodium acetate.

[0025] These may be used alone or in combination of two or more. In the case of nonionic surfactants, those with a cloud point of about 30 to 80°C are preferably used. Among these, an aqueous ammonia solution of a zinc compound, which is an inorganic heat-sensitive gelling agent, is more preferably used in terms of the gelling properties of the water-based primer for road markings.

[0026] A specific example of the zinc compound is zinc hydroxide, and the concentration of the aqueous ammonia solution of the zinc compound is preferably in the range of 5 to 15% by weight. Within this range, the thermosensitive gelling agent can be added stably and the gelling property is also good. The concentration of the ammonia water for dissolving the zinc compound is not particularly limited, and is preferably about 5 to 10 wt %.

[0027] The gelling temperature of this water-based primer for road markings is preferably adjusted to the range of 30 to 100°C. The setting of this gelling temperature can be affected by the temperature. Considering the winter season when this water-based primer for road markings dries more slowly, if the temperature is 30°C or higher, it will not gel during storage in a warehouse, etc., and can be painted while retaining its fluidity.

[0028] Subsequent heating can also be easily carried out, and a gelled film or primer coating film of water-based primer for road markings with sufficient strength can be formed. In summer, the gelling temperature is preferably 50°C or higher, and when considering storage stability throughout the year, it is preferable to set the gelling temperature within the range of 60 to 100°C.

[0029] Within this range, storage stability and paintability are good, the formation of a primer coating film formed from the water-based primer for road markings is facilitated, and when heated, water vapor is generated just before gelation, and swelling due to the water vapor generated when the primer coating film is formed is reduced. This water-based primer for road markings can be applied using a paint roller, brush or spray.

[0030] Of these, spraying is preferred, as the air in the paint is released when the fine paint particles are released into the atmosphere, creating a wet coating film with few bubbles.When the coating is then heated, the few bubbles mean that the gelled film will swell less when the water-based primer for road markings is formed. This is because if air bubbles remain in the wet coating film, when the coating film is heated from the surface, gelation will proceed from the surface of the coating film, and the air bubbles remaining inside the coating film will expand due to heating, causing blisters to form on the surface of the coating film.

[0031] This spray application method uses spray guns such as air sprays and airless sprays that are normally used in painting work, and these are often used with marker vehicles loaded onto cars or handcarts, often to improve work efficiency. In addition to spray application, when the application area is relatively small, application may be performed using common painting tools such as a painting roller or brush, taking into account the need to prevent the water-based primer from scattering during application and the ease of application.

[0032] This water-based primer for road markings can contain other additives such as low-boiling alcohols, surfactants, thickeners, flame retardants, pH adjusters, preservatives, and other ingredients that are commonly used in paint manufacturing. Surfactants are used as defoamers, dispersants, wetting agents, etc. Thickeners are used to adjust viscosity and viscosity.

[0033] Furthermore, this water-based primer for road markings can be colored as needed by adding coloring components such as white pigments such as titanium oxide, kaolin, talc, and clay, inorganic pigments such as iron oxide, and organic pigments. It is also possible to add extender pigments such as calcium carbonate, diatomaceous earth, bentonite, white carbon, glass beads, plastic beads, aluminum hydroxide, precipitated barium, and silica sand.

[0034] This water-based primer for road markings can be obtained by mixing and stirring the various materials described above. This water-based primer for road markings preferably has adhesiveness when dried after application, which improves adhesion between the primer coating and the coating formed by the road marking paint.

[0035] This adhesiveness can be adjusted by the glass transition temperature of the synthetic resin used in the water-based primer for road markings or by adding a high-boiling point solvent. Therefore, the glass transition temperature of this synthetic resin is preferably in the range of -15 to 20°C, and if it is within this range, sufficient adhesiveness will be obtained. Furthermore, by including a high-boiling point solvent with a boiling point of 100°C or higher, the adhesiveness of the primer coating film formed by the water-based primer for road markings is increased, further improving the adhesion of the coating film formed by the road marking paint.

[0036] Examples of such high boiling point solvents include aliphatic hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons, alcohols, ketones, esters, alcohol esters, ketone esters, ethers, ketone alcohols, ether alcohols, ketone ethers, and ester ethers. Furthermore, materials that are generally used as film-forming aids or antifreeze agents in water-based paints can be used, and these can be appropriately selected and used.

[0037] Specific examples include alcohols such as ethylene glycol, propylene glycol, hexylene glycol, and benzyl alcohol, and aromatics such as diethyl phthalate, dioctyl phthalate, ethylphthalyl ethylene glycolate, nonane, methylbenzene, and alkylbenzene. Examples include esters such as 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate and propylene glycol diacetate, turpentine oil, and the like.

[0038] Further examples include alkyl ethers such as butyl glycol, butyl diglycol, ethyl diglycol, dipropylene glycol methyl ether, dipropylene glycol n-butyl ether, tripropylene glycol n-butyl ether, diethylene glycol monobutyl ether acetate, propylene glycol methyl ether acetate, diethylene glycol dimethyl ether, and triethylene glycol monomethyl ether.

[0039] Any one of these may be used alone or in combination of two or more, and it is necessary that they are miscible with the synthetic resin emulsion. Low-boiling solvents with boiling points below 100°C are highly volatile and may volatilize when the water-based primer for road markings is heated, making it impossible to obtain sufficient adhesion. Furthermore, they may be undesirable in terms of safety and environmental impact.

[0040] It is more preferable to use only high boiling point solvents having a boiling point in the range of 100 to 350° C. Two or more high boiling point solvents in the range of 100 to 350° C. may be used, each containing 5.0 to 60.0% by weight of OH groups in terms of molecular weight per molecule. If the boiling point of the high-boiling solvent is 350°C or higher, the high-boiling solvent will remain in the coating film obtained from the aqueous primer composition for a long period of time, which may cause swelling. Furthermore, the boiling point of the organic solvent is more preferably in the range of 150 to 300°C, as this range provides a good balance.

[0041] This high boiling point solvent is mixed with the synthetic resin emulsion, and therefore a water-soluble high boiling point solvent may be preferably used. Tackifiers can also be added to this water-based primer for road markings, including natural resins such as plant-derived rosin, animal-derived shellac, and mineral-derived asphalt. Synthetic resins include ester resins derived from natural resin rosin, petroleum resins, and terpene phenol resins.

[0042] Among these, ester resins derived from natural resin rosin are often used due to their ease of availability, etc. These tackifiers can improve the adhesion performance of aqueous primers, and can be selected and used as appropriate, and these can also be used alone or in combination of two or more types. The amount of water-based primer to be applied depends on the shape of the object to be painted, but is usually 10 to 100 g / m 2 This is because when the object to be painted is a road surface, the amount of paint applied may be relatively large depending on how the road surface is paved.

[0043] After such a water-based primer for road markings has been applied, a road marking paint is then applied. After the water-based primer for road markings has been applied, the surface may be heated to form a gelled film of the water-based primer for road markings, and then the road marking paint may be applied. In some cases, a water-based road marking primer is applied, and the heat of melting of the melting type road marking paint is used to gel the water-based road marking primer while the melting type road marking paint is being applied.

[0044] The heating method when heating the water-based primer for road markings after application is not particularly limited, as long as it can heat the applied water-based primer for road markings in a wet state to a temperature at which it can gel. This heating method includes the use of a burner that utilizes fire, hot air, far infrared rays, etc. However, even if the heating temperature is higher than the gelling temperature of the coating film, if it is relatively low, it may take a long time for the gelling temperature to reach the inside of the coating film, making the work inefficient.

[0045] In addition, heat is absorbed by the temperature during heating and the road surface to be painted, and it can take time for the water-based primer for road markings to gel. For this reason, it is important to select a method that allows for easy temperature control. By using a gas burner or the like, it is easy to apply heat directly to the wet coating film to cause gelation, and sufficient heat can be applied to the wet coating film, allowing the work to be carried out efficiently.

[0046] After forming a coating of the water-based primer for road markings in this way, road marking paint is applied. Typical road marking paints are those specified in the above-mentioned JIS K 5665, and come in the form of water-based or solvent-based liquid paints or melt-type powder paints. The road marking paint is not particularly limited, but it is preferable to apply a melting type road marking paint having a melting temperature in the range of 100 to 250°C in a melted state.

[0047] This allows the temperature of the road marking paint to be used to gel the applied water-based road marking primer, and at the same time, the melt-type road marking paint is applied, further shortening the marking application time. Among these road marking paints, it is also possible to use water-based, heat-sensitive gelling paints, which are preferable because they allow marking work to be carried out efficiently.

[0048] This involves applying to the road surface an aqueous primer for road markings, which is made by adding a heat-sensitive gelling agent to a synthetic resin emulsion and adjusting the gelling temperature to a temperature lower than 100°C. Next, a heat-sensitive gelling agent is added to the synthetic resin emulsion, and a water-based heat-sensitive gel type road marking paint with a gelling temperature adjusted to below 100°C is applied and heated to form a gelled film.

[0049] This allows the application of a water-based heat-sensitive gel type road marking paint immediately after the application of the water-based road marking primer, and the two applied layers are heated simultaneously to gel and dry, thereby eliminating swelling and blisters, shortening the drying time, and ensuring sufficient adhesion to the road marking paint. Therefore, it is easy to handle, contains a small amount of volatile organic solvents, and allows for efficient marking application.

[0050] This water-based heat-sensitive gel type road marking paint is the same as the water-based road marking primer disclosed herein, and its main component is a synthetic resin emulsion to which a heat-sensitive gelling agent has been added, adjusting the gelling temperature to a temperature lower than 100°C, with the other components being similar to those of ordinary water-based road marking paints. Furthermore, the synthetic resin emulsion used is often the same as that used in the water-based primer for road markings, and acrylic synthetic resin emulsions and acrylic-styrene synthetic resin emulsions made from acrylic resin and styrene resin are preferably used.

[0051] The thermosensitive gelling agent added to this synthetic resin emulsion is often the same as that used in aqueous primers for road markings, and an ammoniacal aqueous solution of a zinc compound, which is an inorganic thermosensitive gelling agent, is preferably used. Other ingredients include white pigments such as titanium dioxide, kaolin, talc, and clay, and extender pigments such as calcium carbonate, diatomaceous earth, aluminum hydroxide, bentonite, white carbon, precipitated barium, and silica sand.

[0052] In addition, the ink may contain coloring components such as inorganic pigments, such as iron oxide, or coloring pigments, such as organic pigments, or fibers. If necessary, components that are generally compounded in paint manufacturing, such as surfactants used as dispersants, wetting agents, and antifoaming agents, viscosity adjusters such as thickeners, leveling agents, and anti-sagging agents, low-boiling alcohols, film-forming aids, and organic solvents used as antifreeze agents, can also be used.

[0053] In addition, additives such as pH adjusters, preservatives, mildew inhibitors, algae inhibitors, and waxes may also be added. With the water-based thermosensitive gel type road marking paint having such a configuration, a gelled coating film is formed by heating the applied water-based thermosensitive gel type road marking paint in a wet state.

[0054] This water-based heat-sensitive gel type road marking paint is similar to water-based road marking primers and is a stable liquid at room temperature, but when it reaches the adjusted gelling temperature, the spaces between the synthetic resin components, which are the main component, become narrower, causing them to stick together and causing the paint to lose its fluidity. The gelled coating film contains water, but as the synthetic resin gels, the white pigment, extender pigment, and other components dispersed in the synthetic resin emulsion also become fixed.

[0055] Next, the method of applying the above-described road marking paint will be explained more specifically by using an actual application on an asphalt road surface. This work was planned to cover a distance of approximately 3m, and the work location was cleared of as much dirt and dust as possible. The work was carried out in a daytime environment with a temperature of 25°C, humidity of 60%, and a gentle breeze.

[0056] First, the synthetic resin emulsion used in the water-based primer for road markings is one obtained by emulsion polymerization of acrylic resin, and the solid content is 45.0 wt % and the glass transition temperature is -10°C. The thermosensitive gelling agent used was an aqueous ammonia solution of a zinc compound, in which zinc hydroxide, the zinc compound, was dissolved in aqueous ammonia, with the concentration being 10% by weight.

[0057] This water-based primer for road markings contained ingredients that are generally compounded in paint manufacturing, such as surfactants, thickeners, flame retardants, pH adjusters, and preservatives. In addition, to ensure that this water-based primer for road markings retains adhesiveness after drying, 5.0% by weight of 2,2,4-trimethyl 1,3-pentanediol monoisobutyrate, a high-boiling point solvent with a boiling point of approximately 260°C, was added to the synthetic resin emulsion solids.

[0058] The mixture was used as a water-based primer for road markings, and its gel temperature was set to 80°C. The storage stability of this water-based primer for road markings was confirmed. Two 500 g containers of this water-based primer for road markings were prepared in tightly sealed plastic containers.

[0059] These were left to stand in thermostatic chambers at 50°C and -5°C, respectively, for one week, and then returned to room temperature. The properties of the water-based primer for road markings were then checked, and it was confirmed that there were no particular changes in either case, demonstrating that the storage stability of the water-based primer for road markings was good. This water-based primer for road markings is applied using an air spray, with the application amount being 50 g / m 2 It was about that extent.

[0060] After applying this water-based primer for road markings, a road marking paint was applied, which was a melt-type powder paint specified in JIS K 5665. The melting temperature of this melt-type road marking paint is about 200°C, and a dedicated applicator was used to apply it.

[0061] The period from the application of this water-based primer for road markings to before the application of the road marking paint was checked under the following three different conditions. (1) When a water-based primer for road markings is applied and then allowed to dry naturally to form a primer coating film.

[0062] (2) After applying a water-based primer for road markings, a gelled film is formed using a heating method that utilizes far infrared rays. This was a heating device using far-infrared panels, and heating was carried out while observing the state of the gelled film.

[0063] (3) When the surface remains wet immediately after application of a water-based primer for road markings. After these conditions (1) to (3), a melt-type road marking paint was applied, and the results were as follows.

[0064] In the case of (1), the water-based primer for road markings took a relatively long time to dry, and it took the same amount of time as when a regular water-based primer was used. Furthermore, no bubbling occurred immediately after application of the road marking paint, and the formed coating film was free of blistering and cracking.

[0065] In the case of (2), the application time was significantly shorter than when a solvent-based primer was used. This is because the water-based primer for road markings was heated immediately after application to form a gelled film, leaving almost no time for the water-based primer for road markings to dry. Furthermore, no bubbling occurred immediately after application of the road marking paint, and the formed coating film was free of blistering and cracking.

[0066] In the case of (3), the application time was about the same as when no primer was used, which was significantly shorter than usual. This was because the application of the road marking paint was carried out immediately after the application of the water-based primer for road markings, allowing the painting and application to be carried out almost simultaneously. Furthermore, no bubbling occurred immediately after application of the road marking paint, and the formed coating film was free of blistering and cracking.

[0067] To compare with cases (1) to (3), the same painting was carried out using the water-based primer for road markings, but without the addition of a gelling agent or a high-boiling point solvent, and the same road marking paint was also used. (4) When a water-based primer is applied and then allowed to dry naturally to form a primer coating film.

[0068] (5) When a water-based primer is applied and then a heating method using far-infrared panels is used. This was a heating device that used far-infrared panels, and heating was carried out while observing the situation.

[0069] (6) When the surface is still wet immediately after applying the water-based primer. After the conditions (4) to (6) were met, a melt-type road marking paint was applied, and the results were as follows:

[0070] In the case of (4), the water-based primer took a relatively long time to dry, about the same time as when a regular water-based primer was used. Furthermore, no bubbling occurred immediately after application of the road marking paint, and the formed coating film was free of blistering and cracking.

[0071] In the case of (5), when heated, the water-based primer began to bubble up, causing the primer coating to swell and preventing the formation of a uniform coating. As a result, it was not possible to apply the road marking paint. In case (6), as soon as the road marking paint was applied, moisture from the water-based primer swelled, causing the road marking paint film to swell, making it impossible to carry out the marking work.

[0072] In this way, the water-based primer for road markings to which a gelling agent has been added is easy to handle, does not swell or blister even when heated and dried after application, and can shorten the time until the road marking paint is applied. In addition, by using the heat of the road marking paint to gel the water-based road marking primer and simultaneously applying the melt-type road marking paint, the marking work could be further shortened.

[0073] In this way, the shorter the time between the application of the water-based primer for road marking and the application of the road marking paint, the faster the road marking paint can be applied, which significantly reduces the marking work and the time required for traffic control associated with the work. Next, a water-based primer for road markings was applied using an air spray. The application amount was 70 g / m 2 The marking work was carried out using a water-based heat-sensitive gel type road marking paint. This water-based heat-sensitive gel-type road marking paint used the same acrylic resin-based synthetic resin emulsion (solid content 45.0% by weight, glass transition temperature -10°C) as the water-based road marking primer as the binder, and the heat-sensitive gelling agent was a zinc compound dissolved in ammonia water at a concentration of 10% by weight.

[0074] Titanium oxide and calcium carbonate were added to these, and a surfactant, a thickener, and a pH adjuster were added to obtain a water-based heat-sensitive gel type road marking paint. The pigment volume concentration of this paint was 60% by volume, and the gel temperature was 85°C, slightly higher than that of water-based primers for road markings. This was due to the fact that the paint contained titanium oxide and calcium carbonate.

[0075] Furthermore, since the gelling temperature is higher than that of the water-based road marking primer, which is located on the inside and is less susceptible to heat than the water-based heat-sensitive gel type road marking paint, in the case of (9) described below, the two will gel at roughly the same time, making it less likely that the paint film will blister. This water-based heat-sensitive gel type road marking paint is applied by air spray, and the application amount is 100 g / m 2 It was about that extent.

[0076] The period from the application of this water-based road marking primer to the application of the water-based heat-sensitive gel-type road marking paint was checked under the following three different conditions. (7) After applying a water-based primer for road markings, the primer coating is allowed to dry naturally to form a film, and then a water-based heat-sensitive gel-type road marking paint is applied, followed by heating using a heating device with far-infrared panels while observing the state of the gelled film.

[0077] (8) After applying a water-based primer for road markings, a gelling film is formed using a heating method that utilizes far infrared rays, and after applying a water-based heat-sensitive gel-type road marking paint, the paint is similarly heated to gel and form a coating film. This was a heating device using far-infrared panels, and heating was carried out while observing the state of the gelled film.

[0078] (9) When a water-based heat-sensitive gel type road marking paint is applied to the wet surface immediately after applying a water-based road marking primer, and then the paint is simultaneously gelled using a heating method using far infrared rays to form a gelled film. This was a heating device using far-infrared panels, and heating was carried out while observing the state of the gelled film.

[0079] The results of (7) to (9) were as follows: In the case of (7), the water-based primer for road markings took a relatively long time to dry, about the same time as when a regular water-based primer was used. Furthermore, no bubbling occurred immediately after application of the water-based heat-sensitive gel type road marking paint, and the formed paint film showed no swelling or cracking.

[0080] In the case of (8), the water-based primer for road markings was heated immediately after application to form a gelled film, which meant that there was almost no time for drying, significantly reducing the application time. Furthermore, no bubbling occurred immediately after application of the water-based heat-sensitive gel type road marking paint, and the formed coating film was free of blistering and cracking.

[0081] In the case of (9), by applying the road marking paint immediately after applying the water-based primer for road markings, the painting and application could be carried out almost simultaneously, so the application time was about the same as that for applying melt-type road marking paint without using a primer, and was significantly shorter than when using a water-based primer. Furthermore, no bubbling occurred immediately after application of the water-based heat-sensitive gel type road marking paint, and the formed coating film was free of blistering and cracking.

[0082] Adhesion was confirmed for the application specifications (1) to (9) above. (5) and (6) were excluded from this test because they were unable to form a sufficient coating film. This adhesion was tested by painting the surface of a galvanized steel plate (150mm x 70mm, 1mm thick) and curing it at room temperature for one week to prepare a test specimen. Two test specimens were prepared for each application specification.

[0083] Of these two test specimens, one was tested at room temperature, and the other was left to stand in an atmosphere at -5°C for one day, after which the temperature of the test specimen was lowered to -5°C and the test was then conducted. The test specimen was bent at a 90° angle around the center, and the bent part was checked for peeling of the road marking paint film. Bending causes cracks in the surface of the road marking paint film, and the test was conducted to check whether the cracked paint film would peel off.

[0084] The results confirmed that at room temperature, test pieces (1) to (4) and (7) to (9) did not peel off and had good adhesion. At -5°C, specimens (1) to (3) and (7) to (9) showed no peeling and good adhesion, but specimen (4) showed some peeling of the coating.

[0085] This is because the primer (4) does not contain a high boiling point solvent, so adhesion at low temperatures is slightly reduced.

Claims

1. For the road surface, After applying a water-based primer for road markings, which is a synthetic resin emulsion to which a heat-sensitive gelling agent has been added and whose gelling temperature has been adjusted to a temperature lower than 100°C, A method for applying a road marking paint, comprising applying a water-based heat-sensitive gel type road marking paint in which a heat-sensitive gelling agent is added to a synthetic resin emulsion and the gelling temperature is adjusted to a temperature lower than 100°C.

2. 2. The method for applying a road marking paint according to claim 1, wherein the water-based primer for road marking is applied, heated to form a gelled film, and then the water-based heat-sensitive gel type road marking paint is applied.

3. 2. The method for applying a road marking paint according to claim 1, wherein the water-based heat-sensitive gel type road marking paint is applied after the water-based road marking primer has been applied, and then heated to form a gelled film.