Road marking products with photocatalytic properties, self-cleaning and with a renewable hyperabsorbent surface

p0001The invention relates to a road marking composition and a road marking product further comprising said composition, glass beads and / or anti-skid materials. The road marking composition has photocatalytic properties that give it, once applied to a support, special features such as self-cleaning properties and renewable hyperhydrophile surface. The invention also relates to the use of titanium dioxide in anatase form in a composition or road marking product to renewable hyperhydrophile surface.

p0002A road marking product, whether horizontal or vertical, is subject to its function to the local climatic conditions such as temperature changes, exposure to ultraviolet (UV) and pollution (rain, organic and mineral dust) . This results in a progressive loss of its essential properties that are the daytime visibility characterized by luminance (Q_D), Night visibility characterized by retroreflection (R_L) And the adhesion of the marking characterized by the skid resistance (SRT).

p0003Fouling has a harmful effect on the colorimetry of marking material resulting in a loss of perception of information to the driver or user. Indeed, this fouling, when deposited on the glass ball and particularly in the interstices between the glass beads and / or between the slip materials, is "locked" and partially mask the surface of the beads. This consequently leads to a significant reduction in the visibility of the marking and especially to a loss of retroreflectivity détrimentaire for the driver.

p0004In addition, clogging and abrasion generally related to road traffic cause polishing of the surface of the marking material causing a dramatic decrease in the coefficient of skid resistance, with some impact on user safety, they were motorcyclists or pedestrians in particular.

p0005road marking compositions traditionally comprise a binder, pigments, fillers and additives. The use of titanium dioxide as a pigment in road paints is known. Titanium dioxide exists in several allotropes of which the best known are rutile, anatase and brookite. Titanium dioxide rutile and anatase have a photocatalytic activity. However, the anatase form is much more active than the rutile form.

p0006The photocatalytic effect can be defined as follows. Titanium dioxide (TiO₂) Is a semiconductor oxide known for its photocatalytic properties. Indeed, pairs "electron - hole" are photo-generated when the material is subjected to a lower wavelength of radiation at 400 nm therefore due to natural radiation (sunlight) or artificial (lamp).

p0007These pairs "electron - hole" react with oxygen, moisture from the ambient air and the hydroxyl groups or organic products adsorbed on the surface of titanium dioxide to give radicals including superoxide and hydroxyl radicals very oxidants. Photocatalysis makes it possible to decompose the organic molecules on the surface of titanium dioxide, with the formation of radicals that will initiate a break covalent bonds. Titanium dioxide crystallized in anatase form, by its photocatalytic activity, catalyzes the oxidation of organic compounds.

p0008The photocatalytic properties of titanium dioxide were used in various applications. The majority of studies on photocatalysis TiO₂ door on the mineralization of the exhaust gases and the treatment of air or water.

p0009The patent <patcit id="pcit0001" dnum="WO9707069A"><text>WO 97/07069</text></patcit> also discloses a self-cleaning glass achieved by applying an optically clear coating film and abrasion-resistant based photocatalyst which is titanium dioxide in the anatase form. After exposure to air and light, the film, thanks to its photocatalytic properties, prevents dirt and contaminants to adhere to the glass.

p0010The patent <patcit id="pcit0002" dnum="FR2824846"><text>FR 2824846</text></patcit> discloses a substrate comprising on one of its sides a coating with photocatalytic properties comprising titanium oxide crystallized in anatase form, in an essentially mineral binder comprising at least one semiconducting metal oxide. The substrates described herein are generally all materials used in the construction and especially the glazings. The coatings thus possible to give the material they cover the antifouling properties, fungicides, bactericides, possibly combined with hydrophilic properties, and anti-fog lenses.

p0011There are also paintings including photocatalytic compounds, but these coatings both developed as decontaminating product outdoors or even indoors generally seek by all means to prevent photo-degradation of the binder. These paintings include silicone and non-organic product binders of inorganic binders to prevent the binder is itself degraded by photocatalysis.

p0012The patent application <patcit id="pcit0003" dnum="FR2326461"><text>FR 2326461</text></patcit> discloses pavement marking compositions which comprise as a pigment mixture of titanium dioxide anatase and rutile. However, all examples composition comprising anatase titanium dioxide are solvent borne and comprise as binder an alkyd alkyd resin and optionally paraffins and chlorinated rubber. Furthermore, this document shows no interest to use more particularly titanium dioxide in the anatase form. This is absolutely not used to these photocatalytic properties and a fortiori with the aim to obtain a road marking material having a self-cleaning surface, hyperhydrophile and renewable.

p0013The applicant has surprisingly found that the use of titanium dioxide anatase crystallized in a road marking product comprising an organic type binder provides excellent resistance over time of skid resistance properties, visibility day and night. According to the invention, compositions and road marking products have a low susceptibility to fouling and self-renewable surface properties.

p0014According to its first aspect the present invention therefore relates to a road marking composition comprising by weight based on the total weight of the composition:<ul><li>5 to 50% preferably 10 to 40% of an organic base binder comprising a resin selected from homopolymers or copolymers obtained from vinyl, acrylic or methacrylic polymers, natural or synthetic resins soluble in alcohol or in the optionally modified oils, especially resins of plant derivatives, cellulose, petroleum resins and coumarone-indene resins, polyureas, polyesters and polyethers, aminoplast resins (amino), phenoplasts (phenolic), and the ester -époxydiques, except alkyd resins,</li><li>1 to 40%, preferably 10 to 40% of pigments, 1 to 100% of the total content of pigment is titanium dioxide in anatase crystalline form and</li><li>From 10 to 84%, preferably at least 20% and more preferably from 30 to 84% of fillers.</li></ul>

p0015The invention also relates to a road marking products including road marking and composition of the microbeads and / or anti-skid materials.

p0016The invention also relates to the use of titanium dioxide in anatase form for making a road marking product comprising an organic type binder, which has hyperhydrophiles and renewable surface properties.

p0017The mechanisms underlying the invention based on two properties of titanium dioxide crystallized in anatase form. On the one hand it allows the photocatalytic degradation of the binder constituting the road marking product. On the other hand, it makes the hyperhydrophile surface.

p0018Indeed, titanium dioxide has hyperhydrophiles properties when exposed to UV radiation. The hydrophilicity of a material is measured by the wetting angle, that is to say the angle between a drop of water with the surface of the material. When the titanium dioxide is subjected to UV radiation, this angle decreases to total spreading of the drop. The surface becomes hyperhydrophile and there is no water retainer.

p0019Conventionally, a present marking product surface non-slip material and / or glass beads which give it high skid resistance properties of (high initial SRT). The<figref idrefs="f0001">Figure 1a</figref> illustrates a road marking material 1 with a road marking composition 2 and 3 slip materials protruding from the surface of road marking product. The presence of glass beads or anti-skid materials has the disadvantage of retaining dirt 4 because they are "blocked" between the interstices of slip materials projecting surface. Dirt accumulate on the surface and can not be removed by the traffic.

p0020In the case of conventional road marking product, after a certain wear due to traffic, a polishing phenomenon appears. This phenomenon is illustrated in<figref idrefs="f0001">Figure 1b</figref>. The anti-slip properties tend to decrease.

p0021According to the invention, after exposure to UV light, the organic binder included in the marking composition deteriorates the surface of the marking product contacting titanium dioxide in the anatase form and causes the detachment of dirt. In parallel, the surface being hyperhydrophile, water spreads well on the surface of the road marking, including slides between the degraded surface of the binder and dirt. This phenomenon favors the evacuation of various kinds of dirt and binder degraded. Indeed, the combined action of rain and traffic, allows the detachment and removal of all degraded binder / soil.

p0022In addition, following removal of the upper layer of binder, the surface particles are no longer retained and may be torn off before they are polished by traffic. We therefore renew and the surface condition of the road marking product and therefore its anti-slip properties. This phenomenon is illustrated in<figref idrefs="f0001">Figure 1c</figref>. The invention not only cleans the surface but also to maintain a good performance in terms of skid resistance.

p0023Unlike known applications employing titanium dioxide in anatase form only for the degradation of pollutants, the invention encompasses not only the degradation of dirt but also deterioration of the binder on the surface. Indeed, the dirt can be organic or inorganic in nature but mainly their size is such that degradation would take months or even years. By degrading the binder surface, allows the detachment and therefore removing any type of dirt regardless of their nature or size, but also the uprooting of particle surface and preventing their polishing. This technique has the surprising advantage to renew the surface properties of the road marking product and especially the skid resistance (SRT).

p0024The road marking material according to the invention retains a surface having a luminance factor, of rétroréfection and a high skid resistance over time.

p0025The luminance factor (Q_d) Under diffuse lighting sets the daytime visibility of such a marking perceived by a user at a distance of 30 meters. This coefficient reflects the whiteness of the marking. It is defined according to standard NF EN 1436. The measurement is expressed in millicandelas per lux per square meter (mcd / lux / m²).

p0026Retroreflection (R_L) Night in dry weather, wet or rain, defines night visibility markings as perceived by a driver, at a distance of 30 meters, with the lighting of lights of his vehicle. It is defined according to standard NF EN 1436. The measurement is expressed in millicandelas per lux per square meter (mcd / lux / m²).

p0027The skid resistance SRT sets the value of the adhesion of a marking on the pavement. It is defined according to the NF EN 1436 standard.

p0028Road marking composition according to the invention also has the following features alone or in combination:<ul><li>titanium dioxide in anatase form is crystallized by weight, relative to the total weight of pigment, 2 to 75%, preferably 10 to 40% and more preferably 20 to 30%,</li><li>the composition comprises a mixture of titanium dioxide and crystallized in anatase form of titanium dioxide in the rutile crystalline form,</li><li>the proportions by weight of titanium dioxide crystallized in rutile based on the total weight of the composition is between 1 and 40%, preferably between 5 and 22%, and more preferably between 9 and 18%,</li><li>the composition comprises by weight based on the total weight of the composition 1 to 6%, preferably 2 to 5% and more preferably 3.5% to 4.5% of titanium dioxide in the anatase form,</li><li>organic base binder is solvent-free (if it is thermoplastic), in aqueous phase or organic solvent phase, preferably in aqueous phase,</li><li>the composition may further comprise solvents provided by the binder of an organic base, one or more solvents which may be different or identical to those of the organic base binder,</li><li>binder of organic base in the aqueous phase is an emulsion comprising 30 to 70% of dry extract,</li><li>the organic base binder is preferably an emulsion of at least one acrylic polymer, </li><li>when the composition is in aqueous phase, it comprises less than 10% by weight of organic nature of solvent, preferably less than 5% by weight relative to the total weight of the composition,</li><li>when the composition is solvent-borne, solvent proportions by weight relative to the total weight of the composition are from 10 to 50%,</li><li>when the composition is solvent-free binder proportions are between 5 and 30%</li><li>the fillers are selected from calcium carbonate, amorphous silica or crystallized, fibers or laminar (expenses as a kind talc lamellae)</li><li>the composition comprises by weight based on the total weight:<ul><li>10 to 50%, preferably 30 to 40% of an organic base binder,</li><li>5 to 25%, preferably 10 to 20% pigments,</li><li>20 to 60%, preferably 35 to 45% of fillers,</li></ul></li><li>the total charge rate representing the total amount by weight of fillers and pigments based on the total weight of the composition is greater than or equal to 50%, preferably between 50% and 60%,</li><li>the solids content, by weight relative to the total weight of the composition is greater than 60%, and preferably between 70 and 80%,</li><li>the composition further comprises one or more additives selected from the coalescing agents, antifoams, thickeners, surfactants and dispersants,</li><li>the composition comprises 0 to 4% by weight of additives relative to the total weight of the composition, preferably 1 to 4% by weight.</li></ul>

p0029The invention also relates to the use of anatase titanium dioxide in a road marking composition or a road marking product comprising an organic type binder to provide the composition or the marking produces hyperhydrophiles surface properties and renewable.

p0030The solid content in the sense of the invention is the total dry weight of pigments, fillers and binder. If additives are present, their weight is not included in calculating the total dry weight.

p0031Titanium dioxide in anatase crystalline form has whiteness retention characteristics in the significant time by these photocatalytic properties. preferably titanium dioxide is used in the anatase form having a surface area (BET) greater than 250 m²/ G. This type of product is available commercially. These include TiO₂ anatase Hombikat UV100 of the company Sachtleben, or P25 from Degussa.

p0032The composition according to the invention preferably comprises one or more pigments other than titanium dioxide in the anatase form. These pigments may be inorganic or organic in nature and preferably of very fine particle size (typically &lt;1 micron). By the intended application, the most searched pigments are white and yellow pigments.

p0033Among the mineral pigments conferring white, there may be mentioned other allotropic forms of titanium dioxide and particularly titanium dioxide (TiO₂) Rutile. The rutile titanium dioxide is commercially available under the name including Tioxide TR92 or TiPure R902.

p0034One can also cite as white mineral pigments lithopone (BaSO₄, ZnS), and zinc oxide.

p0035Among the mineral pigments conferring yellow color include yellow bismuth / vanadate (BIOV), yellow chrome titanate / antimony, nickel titanate yellow / antimony, iron oxide, zinc yellow, chrome yellow , lead chromate, cadmium yellow.

p0036Among the existing organic pigments, the most commonly used compounds are: phthalocyanine derivatives, azo compounds (benzidine derivatives, toluidine, dinitroaniline), the isoindoline or isoindolinone pigments, pigments based on di-keto pyrrolopyrrole, anthraquinone derivatives, perylene or thioindigo, quinacridone pigments, dioxazine pigments. As organic pigment yellow include the benzimidazolone, quinazolinediones the quinoxalinediones the arylamide, and their derivatives.

p0037The organic base binder of the invention comprises a resin selected from homopolymers or copolymers obtained from vinyl, acrylic or methacrylic polymers, natural or synthetic resins soluble in alcohol or in optionally modified oils, especially resins plant derivatives, cellulose, petroleum resins and coumarone-indene resins, polyureas, polyesters and polyethers, aminoplast resins (amino), phenoplasts (phenolic), and the epoxy-ester, with the exception of resins alkyds.

p0038The resins suitable for the invention are well known products. These products are also listed in the AFNOR NF T 36-005, which aims to establish a classification of paints, varnishes and related products.

p0039Alkyd resins specifically excluded by the present invention correspond in the NF T 36-005 classification to family 1, class 4. These resins are obtained by esterification of polyhydric alcohols (glycerin, pentaerythritol) with phthalic acids (phthalic anhydride, isophthalic acid, terephthalic) and modified with unsaturated fatty acids or oils. The main fatty acids employed in the synthesis are derived from drying oils or semi-drying. These resins are called alkyd resin.

p0040Vinyl, acrylic, methacrylic or copolymers suitable for the invention correspond in the NF T 36-005 classification to family 1, class 7. These resins are for example described in the patent <patcit id="pcit0004" dnum="US6689824B"><text>US 6689824</text></patcit> and the patent application <patcit id="pcit0005" dnum="WO0160929A"><text>WO 01/60929</text></patcit>. As a vinyl resin, acrylic or methacrylic acid, mention may be made of polyacrylates or methyl or ethyl polymethacrylates, polyvinyl acetate dissolved in a solvent mixture. As a base of a copolymer or terpolymer of vinyl resin, acrylic or methacrylic acid, may be mentioned styrene / acrylic, vinyl acetate / acrylic acid, ethylene / vinyl acetate, vinyl chloride / vinyl acetate or propionate / acrylate, acetate vinyl / versatate copolymers, vinyl acetate / vinyl maleate, acrylic epoxy and acrylic / aminoplast.

p0041Natural or synthetic resins soluble in alcohol or in optionally modified oils suitable for the invention correspond in the NF T 36-005 classification Family 1, 10a class. This class includes gums, hard or soft lacquer, copal resins and rosin. We preferably use resins of vegetable derivatives such as optionally modified rosins (esterified, maleated, hydrogenated etc.). These resins can be used with oil, preferably of plant origin. Is preferably used a mixture of rosin and vegetable oil.

p0042Cellulosic resins suitable for the invention correspond in the NF T 36-005 classification to family 1, class 5. cellulosic resins include nitrocellulose, cellulose acetate, cellulose acetate butyrate; cellulose ethers and esters. These resins may be combined with other binders such as amino resins, vinyl, acrylic, maleic, abiétophénoliques, rosin esters, natural gums, polyurethanes, polyesters.

p0043The petroleum resins (hydrocarbon resins) and coumarone-indene suitable for the invention correspond in the NF T 36-005 classification Family 1, 10 am class. These resins are typically resins prepared from hydrocarbon fractions coming from steam cracking of naphtha, such as aromatic fractions containing monomers selected from styrene and its derivatives, vinyltoluenes and allylbenzene and / or aliphatic cuts containing a monomer having from 5 to 6 carbon atoms such as cyclopentadiene and its derivatives and cyclohexadiene. For example, there may be mentioned hydrocarbon resins sold under the name Escorez^™ by Exxon Chem widely used in hot stamping products.

p0044The amino resins (amino), phenolic (phenolic) and ester-epoxy suitable for the invention correspond in the NF T 36-005 classification Family 1 class 10d, 10e, 10g. The most common amino resins are obtained by polycondensation of formaldehyde (formalin) and urea or melamine. These phenolic resins are obtained by polycondensation of formaldehyde and phenols

p0045Polyester and polyether suitable for the invention correspond in the NF T 36-005 classification Family 1 class 6. This class includes polyurethanes (Class 6A), polyepoxides (Class 6b), saturated polyesters (5c class) and unsaturated polyesters (6d class).

p0046Polyurethanes are formed by reaction between a polyisocyanate and a hydroxy compound which may be a polyhydric alcohol, a polyester, an acrylic resin or, more commonly, atmospheric humidity.

p0047Epoxy resins are formed by reaction of epichlorohydrin with a hydroxy compound (bisphenol A, F or mixture of both), mixed with a hardener. The hardener is a product capable of reacting, or with epichlorohydrin or with the bisphenol. In the first case, the hardeners used are polyamines (e.g., 4,4'-diaminodiphenylmethane), acid (e.g. hexahydrophthalic acid), anhydrides, novolac (thermoplastic phenolic resins), polyamides or polyamino . In the second case, the hardener is either an organic acid or a polyisocyanate. Include for example epoxy-polyamine, epoxy-polyamide, polyurethane epoxy, epoxy-urea-formaldehyde, melamine-formaldehyde epoxy.

p0048Among the polyesters, there are the saturated polyesters and unsaturated polyesters. Unsaturated polyesters derived from the reaction of a diacid on a dialcohol. The resulting compound with a linear structure, is dissolved in a copolymerizable vinyl monomer, usually styrene. The mixture is cured by adding a catalyst. Saturated polyesters, alkyd sometimes improperly called oil-free, are obtained by esterification of polyhydric alcohols with a mixture of phthalic anhydride and an aliphatic diacid or aromatic diacid.

p0049The compositions according to the invention may be solvent borne or waterborne or without solvent in the case of thermoplastic compositions. compositions are preferably used in aqueous phase comprising binder being in aqueous phase.

p0050Within the meaning of the invention, solvent-borne compositions essentially contain organic solvents for the solution treatment (or dispersion) binders which constitute them. The solvents are chosen, for example butyl acetate or ethyl acetate, ketones, toluene, xylene, ethanol, propanol, solvents from renewable plant or animal sources, such as Vegeflux® and bioethanol.

p0051Within the meaning of the invention, the compositions in aqueous phase contain a mixture of water and solvent (hereinafter called "liquid portion"). It is considered that a composition is in aqueous phase if it contains at least 60% by weight of water relative to the total weight of the liquid part of the composition. It is preferred to use a composition comprising less than 30%, preferably less than 20% of organic solvent relative to the total weight of the liquid part of the composition. Also preferred is a composition comprising less than 10%, preferably less than 5% by weight of organic solvent based on the total weight of the composition. Preferentially using this type of composition, that is to say using less volatile organic compounds which evaporate during the drying process considerably reduces the impact on the air but also on the water or soil.

p0052According to a preferred embodiment, an aqueous phase composition and is preferably used a composition comprising an acrylic type binder emulsion in aqueous phase. When the binder is an aqueous emulsion, its water content is between 30 and 70% by weight relative to the total weight of the binder.

p0053The organic base binder thus comprises the organic binder itself or resin and a solvent can be water. Therefore, the compositions of the invention comprise 5 to 20% by weight of organic resin.

p0054The loads can adapt certain mechanical, chemical, electrical and rheological. preferably used fillers of mineral origin. The most frequently used fillers are sulphates, silicates, carbonates such as calcium carbonate (CaCO₃) And dolomite (CaCO₃, MgCO₃), Oxides such as silica (SiO₂) Amorphous or crystallized. Can also be used as filler laminar or fibers.

p0055marking compositions of the invention can be used to manufacture different labeling products such as aqueous road paint or solvent, a coating to hot or cold, a preformed tape.

p0056Preferably a road marking product type road paint or hot or cold coating, further comprising said composition, glass beads and / or anti-skid materials.

p0057marking compositions of the invention are mixed and kept in an appropriate state of agitation before being deposited on the road using such an application machine equipped with sprayers and dispenser.

p0058For example, a water-based paint or solvent-borne or liquid is applied immediately after application (fresh state) at 200 to 1000 g / m².

p0059After the sprayed composition on the surface, the reflective beads and / or friction materials can be immediately dispersed on the composition, so that these materials are partially embedded in the composition. A usual commercial application equipment comprises a spray head for the composition and in combination, a glass bead dispensing device, which is synchronized with the spray head to dispense the glass beads on the freshly applied marking.

p0060Glass beads or retroreflective have a refractive index of 1.50 to 2.4, the most commonly used have an index of 1.52 and are from recycled glass. The particle size ranges from 100 to 1400 or even 2000 microns tiered according to EN 1423/1424. The sprinkled amount varies between 50 and 800 g / m² according to the effect, the size and thickness of the marking product.

p0061The slip materials used in sprinkling must have a Mohs hardness greater than 4. These materials are selected from silica, glass beads, corundum bauxite and ...

p0062In another embodiment, the glass beads are mixed and / or anti-slip material with the composition before its application to the surface. We call this process "pre-mix or premix."

p0063The anti-slip material when incorporated into premixes are considered load "classic", ie included in the proportions of 20 to 60%. The reflective beads incorporated in premixes are small in size and are preferably present in an amount of 10 to 50%.

p0064The compositions of the invention may further comprise one or more conventional additives selected from defoamers, dispersants, coalescing, thickeners and surfactants. The proportions by weight of additives relative to the total weight of the road marking composition is preferably between 0 and 4%.

p0065cold coatings are preferably used in urban areas with heavy traffic, to make urban elements such as pedestrian crossings, folding arrows, checkered, or structured products such as barrettes, VNTP droplets (Night Visibility in Time Rain).

p0066Cold coatings are preferably based on methacrylic resins bicomponent or monocomponent aqueous resins.

p0067Coatings based cold methacrylic bicomponent loaded resins comprise, by weight relative to the total weight of plaster:<ul><li>20% resin (s) and plasticizer,</li><li>50% pigment (s) and fillers, </li><li>30% of glass beads.</li></ul>

p0068Cold coatings based on aqueous one-component filled resins comprise, by weight relative to the total weight of plaster:<ul><li>25 to 35% of binder,</li><li>10 to 20% of pigment (s),</li><li>40 to 70% of fillers,</li><li>0 to 3% of co-solvents,</li><li>0 to 3% of other additives.</li></ul>

p0069Hot coatings are solid thermoplastic products at room temperature, the ring-ball temperature (TBA) is preferably from 70 to 100 ° C. These products are applied between 160 and 220 ° C by spray or flow through a slot (technical jargon called the "curtain" or "shoe").

p0070Hot coatings preferably include hydrocarbon resins and / or vegetable origin, pigments, fillers, glass beads, plasticizers, waxes, and anti-settling agents.

p0071Preferably used hot coated on highways and areas with very heavy traffic.

p0072Preformed strips or marking tape strips are ready for use, usually self-adhesive or heat-sealing. These strips comprise a PU film (polyurethane) that contains ceramic balls, glass and pigments and fillers, placed on a pressure sensitive adhesive.

p0073The term "thickening" generally includes any substance added to paint changes its rheological behavior. As suitable thickener according to the invention include natural thickening agents, and in particular selected from natural gums, CMCs (Carboxymethylcelluloses) and HEC (hydroxyethyl celluloses), or chosen from among the synthetic thickening agents, and in particular selected from synthetic rubbers, acrylic thickeners HASE (Emulsions modified hydrophobically and thickening alkaline or hydrophobically modified alkali-swellable Emulsions) or ESA (Emulsions thickening alkaline or alkali Soluble Emulsions), the thickening urethane hydrophobically modified (CLOC) , polyethers, polyesters, polyvinyl alcohol (PVA) or based on PVP (polyvinylpyrrolidone) or other thickeners such as fumed silica, attapulgite clay and other types of clay, chelating agents. urethanes modified thickener These include hydrophobically ACRYSOL® marketed as RM-825, RM-8W ACRYSOL®, ACRYSOL® RM-12W.

p0074Suitable dispersants according to the invention include nonionic dispersants, anionic, and cationic surfactants such as 2-amino 2-methyl 1-propanol (AMP), dimethyl amino ethanol (DMAE), potassium tripolyphosphate (KTPP), the trisodium polyphosphate (TSPP), citric acid and other carboxylic acids. Anionic polymers such as homopolymers and copolymers based on polycarboxylic acids, e.g., polyacrylic acid or polymethacrylic acid or maleic anhydride modified with various monomers such as styrene, acrylate ester or methacrylate, diisobutylene, and other hydrophilic or hydrophobic comonomers. In addition, also included are the salts of the aforementioned polymers, and mixtures thereof. acrylic dispersant These include marketed by Coatex under the name COATEX® P90.

p0075Suitable defoamers include silicone defoamers oil based and mineral oil. There are also hydrocarbon-based formulations and non-ionic surfactants agents, such as the products sold under the name Foamaster®.

p0076Suitable coalescents include glycol ethers such as ethylene glycol, propylene glycol, 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate (Texanol^™).

p0077Suitable surfactants are selected from cationic surfactants, anionic, and nonionic surfactants conventionally used in the paint formulation. preferably there is used a nonionic surfactant include an ether of polyethylene glycol and a mixture of fatty alcohol such as TERGITOL® product.

p0078The following examples illustrate the compositions of the present invention. All indicated proportions are by weight.

Examples

I. Raw materials

p0079<dl id="dl0001" compact="compact"><dt>Organic binder:</dt><dd>acrylic emulsion (solids content 50%) Fastrack® 2706 sold by the company Rohm and Haas,</dd><dt>pigments:</dt><dd>titanium dioxide in the anatase form: Hombikat® UV100 (100% anatase, specific surface (BET):> 300 m²/ G);</dd><dt>Rutile titanium dioxide:</dt><dd>TIPURE® R902 marketed by DuPont,</dd><dt>charges:</dt><dd>calcium carbonate, Durcal® 5 of OMYA,</dd><dt>additives:</dt><dd>coalescent: Texanol® Defoamers: Foamaster® 8034 Thickening: Acrysol® RM12W, Surfactant: Tergitol® 15S40, Acrylic dispersant: Coatex® P90.</dd></dl>

II. Influence of the proportions of TiO₂ anatase on viscosity

p0080This test aims to assess the influence of the proportions of TiO₂ anatase heavily on photocatalytic properties of the road marking composition. Compositions comprising different contents of TiO₂ anatase and rutile were prepared. TiO₂ anatase has a greater oil absorption as TiO₂ rutile. Where the proportions of TiO₂ anatase increases, the charging rate (total weight of fillers and pigments) decreases.

p0081In order to evaluate the influence of the proportions of TiO₂The following control composition was performed:<ul><li>Acrylic binder in aqueous phase: 35%</li><li>TiO₂ rutile: 17.98%</li><li>Charges: 39%</li><li>Water: 2.5%</li><li>Cosolvent: 4.2%</li><li>Additives: 1.32%</li></ul>

p0082Then, the compositions 1-4 were carried out by varying the proportions of anatase titanium, rutile titanium dioxide and filler. The viscosity was measured using a Brookfield viscometer (spindle No. 4, speed 10 rpm, product temperature 21 ° C, 1 day after manufacture).

p0083The resins are prepared by mixing the various constituents in the following order:<ul><li>addition of the resin,</li><li>then if the following compounds are used addition of the defoamer and surfactant, then the dispersant,</li><li>adding pigments,</li><li>adding fillers,</li><li>then optionally the solvent and finally coalescing.</li></ul>

p0084These road aqueous paints are intended to be sprayed without air (airless) on machine.

p0085Table 1 lists the various compositions prepared and the viscosity obtained for each composition.<tables id="tabl0001" num="0001"><table frame="all"><title>Table 1: Variation of viscosity in function of the proportions of TiO₂ anatase</title><tgroup cols="6"><colspec colnum="1" colname="col1" colwidth="35mm" /><colspec colnum="2" colname="col2" colwidth="34mm" /><colspec colnum="3" colname="col3" colwidth="25mm" /><colspec colnum="4" colname="col4" colwidth="25mm" /><colspec colnum="5" colname="col5" colwidth="25mm" /><colspec colnum="6" colname="col6" colwidth="25mm" /><thead><row><entry align="center" valign="middle">Formula</entry><entry align="center" valign="middle">control composition</entry><entry align="center" valign="middle">composition 1</entry><entry align="center" valign="middle">composition 2</entry><entry align="center" valign="middle">composition 3</entry><entry align="center" valign="middle">composition 4</entry></row></thead><tbody><row><entry align="center" valign="middle">% TiO₂ rutile</entry><entry align="center" valign="middle">17.98</entry><entry align="center" valign="middle">13.49</entry><entry align="center" valign="middle">8.99</entry><entry align="center" valign="middle">4.50</entry><entry align="center" valign="middle">0</entry></row><row><entry align="center" valign="middle">% TiO₂ anatase</entry><entry align="center" valign="middle">0</entry><entry align="center" valign="middle">2.46</entry><entry align="center" valign="middle">4.93</entry><entry align="center" valign="middle">7.39</entry><entry align="center" valign="middle">9.85</entry></row><row><entry align="center" valign="middle">load rate</entry><entry align="center" valign="middle">57.01</entry><entry align="center" valign="middle">55.82</entry><entry align="center" valign="middle">54.62</entry><entry align="center" valign="middle">53.43</entry><entry align="center" valign="middle">52.24</entry></row><row><entry align="center" valign="middle">Brookfield Viscosity (cps)</entry><entry align="center" valign="middle">2300</entry><entry align="center" valign="middle">2630</entry><entry align="center" valign="middle">4000</entry><entry align="center" valign="middle">4600</entry><entry align="center" valign="middle">> 14000</entry></row></tbody></tgroup></table></tables>

p0086Table 1 and the <figref idrefs="f0002">2</figref> which represent the change in viscosity as a function of titanium dioxide content in the anatase form, show that the road marking composition has a viscosity optimum for proportions of TiO₂ anatase less than 6% by weight relative to the total weight of the composition, most preferably less than 5% by weight relative to the total weight of the composition, corresponding to a 35% content by weight of anatase titanium based on the total weight of pigment.

p0087The change in viscosity was also measured using a flow chart. The rheogram measuring the evolution of the viscosity (in mPa.s) as a function of shear rate (in s^-1) On a rheometer with a mobile cone / plane constraint imposed such Rheostress 600 from Thermo Electron. The gradient ranged from 10^-4 10³ s^-1This allows estimating the behavior of painting during his lifetime: the storage, during transport, mixing, spraying her and stretched once placed on the ground.

p0088The measured flow chart shown <figref idrefs="f0002">3</figref> confirms the general trend of viscosity whatever the shear rate. It is found that a mixture comprising 2.5% by weight of TiO₂ anatase relative to the total weight of the composition has a rheogram identical to a composition comprising only rutile titanium dioxide. This corresponds to a composition comprising 15% by weight of anatase titanium based on the total weight of pigment.

III. Influence of the proportions of TiO₂ anatase on coverage

A. Measurement of the coverage map on Leneta Form 24B

p0089This is consistent with the standard NFT 30075. The Leneta card 24B has straps with a gradient from white (score of 0) to black (note 6). The measure is to apply different thicknesses controlled paint and then measure from which band (rated from 1 to 6) are distinguished contrast. 6 is a perfect hiding power, arbitrarily 3 is considered as the minimum to be used as paint.<tables id="tabl0002" num="0002"><table frame="all"><title>Table 2: Influence of the proportions of TiO₂ anatase on coverage</title><tgroup cols="6"><colspec colnum="1" colname="col1" colwidth="34mm" /><colspec colnum="2" colname="col2" colwidth="34mm" /><colspec colnum="3" colname="col3" colwidth="25mm" /><colspec colnum="4" colname="col4" colwidth="25mm" /><colspec colnum="5" colname="col5" colwidth="25mm" /><colspec colnum="6" colname="col6" colwidth="25mm" /><thead><row><entry align="center" valign="top">fresh Thickness (microns)</entry><entry align="center" valign="top">control composition</entry><entry align="center" valign="top">composition 1</entry><entry align="center" valign="top">composition 2</entry><entry align="center" valign="top">composition 3</entry><entry align="center" valign="top">composition 4</entry></row></thead><tbody><row><entry align="center">225</entry><entry align="center">5</entry><entry align="center">4</entry><entry align="center">3</entry><entry align="center">2</entry><entry align="center">1</entry></row><row><entry align="center">250</entry><entry align="center">5</entry><entry align="center">4</entry><entry align="center">3</entry><entry align="center">2</entry><entry align="center">1</entry></row><row><entry align="center">275</entry><entry align="center">5</entry><entry align="center">5</entry><entry align="center">3</entry><entry align="center">2</entry><entry align="center">1</entry></row><row><entry align="center">300</entry><entry align="center">5</entry><entry align="center">5</entry><entry align="center">4</entry><entry align="center">3</entry><entry align="center">1</entry></row><row><entry align="center">350</entry><entry align="center">6</entry><entry align="center">5</entry><entry align="center">4</entry><entry align="center">3</entry><entry align="center">1</entry></row><row><entry align="center">400</entry><entry align="center">6</entry><entry align="center">6</entry><entry align="center">5</entry><entry align="center">3</entry><entry align="center">1</entry></row></tbody></tgroup></table></tables>

p0090Titanium dioxide in anatase form is used having a nanometric granulometry which may affect the covering power and the same on the retroreflection. The influence of nanoscale TiO₂ anatase is really about the ability extender TiO₂ rutile because it will tend towards the spacing of particles of TiO₂ rutile, which will allow to provide a better dispersion thereof in the matrix. By its nanoscale, TiO₂ anatase has a low hiding power: it is translucent to light. This is why we can not use it without the presence of TiO₂ rutile, which is bigger and has a high refractive index.

p0091The above table clearly shows that the composition has a good coverage even in a thin layer to the proportions of TiO₂ less than or equal to 5% anatase.

p0092From 5% titanium dioxide in the anatase form and therefore a filler content of 54.62%, the hiding power of the composition is insufficient in thin (300 microns or about 500 g / m²). The composition comprises only 4 TiO₂ anatase does not have excellent coverage.

B. Measurement of power covering a Leneta card 2A

p0093Measuring the luminance ratio (Y) on a white background (YB) to black (YN). The higher the ratio is greater than or equal to 1 and the covering is more important.

p0094This measurement is performed in accordance with EN 1436. The principle is the same as that described above, except that the measurement is between a black background and white background for a given thickness and that the measure is with a spectrophotometer by measuring the tristimulus parameters Y and x and y.<tables id="tabl0003" num="0003"><table frame="all"><title>Table 3: Influence of the proportions of TiO₂ anatase on coverage</title><tgroup cols="6"><colspec colnum="1" colname="col1" colwidth="35mm" /><colspec colnum="2" colname="col2" colwidth="34mm" /><colspec colnum="3" colname="col3" colwidth="25mm" /><colspec colnum="4" colname="col4" colwidth="25mm" /><colspec colnum="5" colname="col5" colwidth="25mm" /><colspec colnum="6" colname="col6" colwidth="25mm" /><thead><row><entry align="center" valign="top">Covering 250 microns fees</entry><entry align="center" valign="top">control composition</entry><entry align="center" valign="top">composition 1</entry><entry align="center" valign="top">composition 2</entry><entry align="center" valign="top">composition 3</entry><entry align="center" valign="top">composition 4</entry></row></thead><tbody><row><entry align="center">YB</entry><entry align="center">88.37</entry><entry align="center">88.28</entry><entry align="center">86,14</entry><entry align="center">86.08</entry><entry align="center">80.58</entry></row><row><entry align="center">YN</entry><entry align="center">88.41</entry><entry align="center">87.17</entry><entry align="center">87,05</entry><entry align="center">82.27</entry><entry align="center">71.97</entry></row><row><entry align="center">YN / YB</entry><entry align="center">1,005</entry><entry align="center">0.987</entry><entry align="center">1011</entry><entry align="center">0.956</entry><entry align="center">0.893</entry></row></tbody></tgroup></table></tables>

p0095Thus, it is found that the covering power is greatly reduced for compositions comprising more than 5% of titanium dioxide in anatase form in thin layer (250 .mu.m).

IV. Influence on the hardness of the film

p0096Measuring the hardness Persoz is to measure the damping time of a pendulum resting, by means of two steel balls on the film to be studied. The hardness is expressed in seconds, which corresponds to the number of oscillations of the pendulum when it is inclined by 12 ° relative to the normal to the origin and 4 ° which corresponds to the end of the test (standard NFT 30- 016).

p0097The tests were carried out on films of 400 microns. The measurements were performed 1 day and 6 days after drying at room temperature in the lab, and after aging WOM (Weather-O-Meter).

p0098WOM is an accelerated aging test according to standard NFT 30-049, with a Xenon lamp and integrating a series of cycles including rain, moist heat, dry heat, freeze / thaw, sunshine. 5-day cycles represents 1.5 years of natural aging on location in Paris.<tables id="tabl0004" num="0004"><table frame="all"><title>Table 4: Influence of the proportions of TiO₂ anatase on hardness</title><tgroup cols="6"><colspec colnum="1" colname="col1" colwidth="35mm" /><colspec colnum="2" colname="col2" colwidth="34mm" /><colspec colnum="3" colname="col3" colwidth="25mm" /><colspec colnum="4" colname="col4" colwidth="25mm" /><colspec colnum="5" colname="col5" colwidth="25mm" /><colspec colnum="6" colname="col6" colwidth="25mm" /><thead><row><entry align="center" valign="top">Persoz Hardness (s) 400 microns fees</entry><entry align="center" valign="top">control composition</entry><entry align="center" valign="top">composition 1</entry><entry align="center" valign="top">composition 2</entry><entry align="center" valign="top">composition 3</entry><entry align="center" valign="top">composition 4</entry></row></thead><tbody><row><entry align="center">D + 1</entry><entry align="center">26</entry><entry align="center">29</entry><entry align="center">33</entry><entry align="center">39</entry><entry align="center">42</entry></row><row><entry align="center">D + 6</entry><entry align="center">28</entry><entry align="center">31</entry><entry align="center">34</entry><entry align="center">40</entry><entry align="center">43</entry></row><row><entry align="center">After 5d WOM</entry><entry align="center">41</entry><entry align="center">49</entry><entry align="center">68</entry><entry align="center">77</entry><entry align="center">97</entry></row></tbody></tgroup></table></tables>

p0099There is a significant variation in the Persoz hardness of the films based on titanium dioxide anatase proportions especially after accelerated aging. Increasing proportions of TiO₂ anatase in the compositions tends to increase the hardness of the films even when the filler content decreases. As observed in previous steps, the addition to a composition of 2.5% titanium dioxide in anatase form does not cause significant changes of this property. The hardness increases from +10 to + 20% maximum.

p0100Despite significant film hardness, it is not observed "cracking" after accelerated aging (WOM) including the formula comprising 100% titanium dioxide in the anatase form.

V. Influence shine

p0101The gloss was measured according to ISO standard 7668 using a gloss BRAIVE LMG064.<tables id="tabl0005" num="0005"><table frame="all"><title>Table 5: Influence of the proportions of TiO₂ anatase on the brightness</title><tgroup cols="6"><colspec colnum="1" colname="col1" colwidth="35mm" /><colspec colnum="2" colname="col2" colwidth="34mm" /><colspec colnum="3" colname="col3" colwidth="25mm" /><colspec colnum="4" colname="col4" colwidth="25mm" /><colspec colnum="5" colname="col5" colwidth="25mm" /><colspec colnum="6" colname="col6" colwidth="25mm" /><thead><row><entry align="center" valign="top">Brightness 250 microns L2B</entry><entry align="center" valign="top">control composition</entry><entry align="center" valign="top">composition 1</entry><entry align="center" valign="top">composition 2</entry><entry align="center" valign="top">composition 3</entry><entry align="center" valign="top">composition 4</entry></row></thead><tbody><row><entry align="center">20 °</entry><entry align="center">1.9</entry><entry align="center">1.7</entry><entry align="center">1.7</entry><entry align="center">1.7</entry><entry align="center">1.6</entry></row><row><entry align="center">60 °</entry><entry align="center">3.2</entry><entry align="center">3.0</entry><entry align="center">3.0</entry><entry align="center">2.7</entry><entry align="center">2.6</entry></row><row><entry align="center">85 °</entry><entry align="center">3.5</entry><entry align="center">3.2</entry><entry align="center">2.7</entry><entry align="center">2.1</entry><entry align="center">1.4</entry></row></tbody></tgroup></table></tables>

p0102the most discriminating angle is the most boring (85 °). Replacement of rutile titanium dioxide with titanium dioxide in the anatase form causes loss of gloss characteristic of a relatively more porous surface. However, this property is sought to present a greater contact area between the TiO₂ anatase and UV radiation.

VI. photocatalytic degradation of paints

p0103To highlight the desired phenomenon, a method for quantifying the chalking phenomenon was developed. When paint is too exposed to the air and to external attacks, the binder is damaged and a kind of powder forms on the surface. Such a phenomenon is called "chalking". This method has the advantage of the formulations according differentiate their photodegradation before / after accelerated aging in the WOM.

p0104A scotch (GPI) precise surface (5x5 cm) is weighed on precision balance and then is brought into intimate contact with the surface of the paint film for 1 minute. At the end of this period, it is removed and weighed again. The gradient binder will adhere directly to the tape film.

p0105The table below brings together against climate measures after accelerated aging in WOM (5d according to the conventional cycle).<tables id="tabl0006" num="0006"><table frame="all"><title>Table 6: Influence of the proportions of TiO₂ anatase on photodegradation</title><tgroup cols="6"><colspec colnum="1" colname="col1" colwidth="35mm" /><colspec colnum="2" colname="col2" colwidth="34mm" /><colspec colnum="3" colname="col3" colwidth="25mm" /><colspec colnum="4" colname="col4" colwidth="25mm" /><colspec colnum="5" colname="col5" colwidth="25mm" /><colspec colnum="6" colname="col6" colwidth="25mm" /><thead><row><entry align="center" valign="top">Chalking after 5d WOM</entry><entry align="center" valign="top">control composition</entry><entry align="center" valign="top">composition 1</entry><entry align="center" valign="top">composition 2</entry><entry align="center" valign="top">composition 3</entry><entry align="center" valign="top">composition 4</entry></row></thead><tbody><row><entry align="center">Scotch mass (g)</entry><entry align="center">0.0007</entry><entry align="center">0.0011 1</entry><entry align="center">0.0016</entry><entry align="center">0.0024</entry><entry align="center">0.0044</entry></row><row><entry align="center">% Relative to the control composition</entry><entry align="center">0</entry><entry align="center">+ 60%</entry><entry align="center">+ 130%</entry><entry align="center">+ 250%</entry><entry align="center">+ 500%</entry></row></tbody></tgroup></table></tables>

p0106Photodegradation of binding is observed for a composition comprising 2.5% of titanium dioxide in the anatase form. The<figref idrefs="f0003">4</figref> represents the percentage of binder gradient relative to the control composition based on titanium dioxide ratio in the anatase form. The phenomenon varies according to a substantially exponential distribution with the amount of TiO₂ anatase.

p0107Another test was conducted in the WOM, but in a cycle with only the radiation from the lamp without rain or wet heat. No differences were observed between the different formulations. This demonstrates that the photocatalysis phenomenon requires not only TiO₂ anatase and UV radiation, but also the presence of water and O₂ in direct contact with the catalyst.

VII. Impact on the surface tension

p0108To quantify the super-hydrophilic phenomenon of a film obtained from the composition, the measurement of the angle of the contact drop was adapted. The test involved applying a drop of blood pressure using "Mobile Drop" of the Company Kruss, then measuring the contact angle between the droplet and the substrate using the dedicated software of DSA2 Kruss the company before and after accelerated weathering WOM. Before aging, the angle of droplets is identical and equal to 72 °.<tables id="tabl0007" num="0007"><table frame="all"><title>Table 7: Influence of the proportions of TiO₂ on the hydrophilicity</title><tgroup cols="6"><colspec colnum="1" colname="col1" colwidth="32mm" /><colspec colnum="2" colname="col2" colwidth="35mm" /><colspec colnum="3" colname="col3" colwidth="25mm" /><colspec colnum="4" colname="col4" colwidth="25mm" /><colspec colnum="5" colname="col5" colwidth="25mm" /><colspec colnum="6" colname="col6" colwidth="25mm" /><thead><row><entry align="center" valign="top">After 5d WOM</entry><entry align="center" valign="top">control composition 0</entry><entry align="center" valign="top">composition 1</entry><entry align="center" valign="top">composition 2</entry><entry align="center" valign="top">composition 3</entry><entry align="center" valign="top">composition 4</entry></row></thead><tbody><row><entry align="center">Contact angle (°)</entry><entry align="center">69.1</entry><entry align="center">31.4</entry><entry align="center">29.6</entry><entry align="center">0</entry><entry align="center">0</entry></row></tbody></tgroup></table></tables>

p0109The <figref idrefs="f0003">5</figref> shows photographs of different media including film compositions 0-4 after weathering accelerated WOM.

p0110We clearly see the status change of the film surface. The more the angle of the droplet decreases, water (very high surface tension: 72 mN / m) tends to wet the support. The surface tension of the water does not vary, it is mandatory that of the support increases. The film surface tends to least slow the spread of the drop.

VIII. Conclusion

p0111Tests have shown that the road marking composition has a viscosity optimum for proportions of TiO₂ anatase by weight relative to the total weight of the composition, less than 6%, most preferably less than 5%. These tests have also shown that the composition has good covering power even in thin layer for proportions of TiO₂ anatase lower or equal to 5% and an excellent covering for proportions of TiO₂ anatase 2.5%. Finally, the photodegradation phenomenon of the binder and hyperhydrophilie is observed for a composition comprising 2.5% of titanium dioxide in the anatase form.

p0112A compromise between these different properties leads to the following formula:<tables id="tabl0008" num="0008"><table frame="none"><tgroup cols="4" colsep="0" rowsep="0"><colspec colnum="1" colname="col1" colwidth="27mm" /><colspec colnum="2" colname="col2" colwidth="17mm" /><colspec colnum="3" colname="col3" colwidth="25mm" /><colspec colnum="4" colname="col4" colwidth="15mm" /><tbody><row><entry>acrylic binder:</entry><entry>35.16%</entry><entry>Thickening:</entry><entry>0.02%</entry></row><row><entry>TiO₂ anatase:</entry><entry>3.94%</entry><entry>surfactant:</entry><entry>0.12%</entry></row><row><entry>TiO₂ rutile:</entry><entry>10.79%</entry><entry>dispersant:</entry><entry>0.52%</entry></row><row><entry>charges:</entry><entry>40.37%</entry><entry>water:</entry><entry>2.53%</entry></row><row><entry>coalescing:</entry><entry>2.08%</entry><entry>Ethanol:</entry><entry>4.16%</entry></row><row><entry>defoamers:</entry><entry>0.31%</entry></row></tbody></tgroup></table></tables>