Classifications

• • E—FIXED CONSTRUCTIONS
  • E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
  • E01C—CONSTRUCTION OF, OR SURFACES FOR, ROADS, SPORTS GROUNDS, OR THE LIKE; MACHINES OR AUXILIARY TOOLS FOR CONSTRUCTION OR REPAIR
  • E01C23/00—Auxiliary devices or arrangements for constructing, repairing, reconditioning, or taking-up road or like surfaces
  • E01C23/16—Devices for marking-out, applying, or forming traffic or like markings on finished paving; Protecting fresh markings
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
  • C09D5/004—Reflecting paints; Signal paints

Definitions

• This invention relates to a method of producing traffic markings which readily adheres to various substrates associated with roads and highways. More particularly, the method of the present invention is useful as a traffic paint which readily adheres to roadbeds that have an oily surface.
• White and yellow traffic markings used for demarcating traffic lanes are a common sight on almost all roads. These markings provide the necessary guidance to ensure safe driving conditions under varying weather conditions.
• the term “roads” is more expansive than merely streets and highways. “Roads” is used herein as a generic term and it includes any indoor or outdoor solid surface that is or may be exposed to pedestrians, moving vehicles, tractors or aircraft, either continuously, continually or intermittently. Some examples or “roads” include highways, streets, driveways, sidewalks, runways, taxiing areas, tarmac, parking lots and indoor floors (such as factory floors or floors inside shopping malls).
• roads may be masonry, asphalt, resins, concrete, cement, stone, stucco, tiles, wood, polymeric materials and any combinations thereof. Also, as used herein, “roads” embraces any surface of any substrate associated with roads, including, for example, signs, barricades, medial strips and traffic signal devices.
• One source of oil on road surfaces are “patches” which are used to cover holes or cracks in older roadbeds.
• Another source of oil are materials known as “sealers” which are used to resurface an entire roadbed.
• An example of such a material is commonly known as “chip seal”, which consists of stone, rocks or sand mixed in or applied over a layer of asphalt or asphalt based emulsion products.
• the stone chips are washed in kerosene or such similar solvent prior to application onto the roadbed. Residual amounts of these solvents on the stone chips will result in an even reduced potential for adhesion.
• the present invention solves the problem of making traffic paint adhere to an oily roadbed by providing a composition consisting of a polymer having a low Tg that is generated from a mixture of monomers, wherein from 10% to 99.9% of these monomers are hydrophobic.
• U.S. Pat. No. 6,228,901 B1 discloses polymers having a higher Tg that are produced from a variety of monomers, at least some of which are hydrophobic, which impart improved wear resistance to traffic paint formulations.
• this patent does not address the issue of providing a traffic paint formulation which may be successfully applied to road surfaces which are covered with an oily film.
• a method for improving the adhesion of traffic paint on oily road surfaces by applying onto the road surface a layer of an aqueous traffic paint which contains a low molecular weight polymer having a Tg of from ⁇ 25° C. to +25° C. that is polymerized from a monomer mixture containing from 10% to 99.9%, by weight, based on the total weight of the polymer solids, of at least one hydrophobic monomer, wherein the relationship between the Tg of the polymer and the hydrophobic monomer content of the polymer is such that when the Tg of the polymer is between ⁇ 25° C.
• the hydrophobic monomer content may be as low as 10%, up to a maximum of 99.9%.
• the hydrophobic monomer content of the polymer must be at least 20% up to the maximum of 99.9%.
• one or more vinyl aromatic monomers may represent all or a portion of the hydrophobic monomer content.
• the preferred amount of vinyl aromatic monomers is from 0.1 to 50%, based on the total weight of the polymer. If, however, only a low percentage of vinyl aromatic monomer is used, such as, for example, 5%, then other hydrophobic monomers must be present in an amount of at least 5% so that the minimum total percentage of hydrophobic monomer content is at least 10%.
• Polymer means a dispersed, solubilized or a sequential polymer, as defined below.
• Dispersed polymer means particles of polymer colloidally dispersed and stabilized in an aqueous medium.
• Solubilized polymer includes “water soluble polymer”, “water reducible polymer” or a mixture thereof.
• Water soluble polymer means a polymer dissolved in an aqueous medium.
• Water reducible polymer means a polymer dissolved in water and a water miscible organic solvent, such as, methanol, ethanol and glycol ethers.
• Solubilized polymer describes a polymer solution characterized by having the self-crowding constant (K) of the Mooney equation equal to zero. By contrast, a dispersed polymer has K equal to 1.9.
• “Sequential polymer” means a polymer which includes particles containing two or more polymeric phases, such as, for example, an inner phase, and an outer phase, wherein the outer phase is the predominant phase in contact with the aqueous medium in which the particle is dispersed.
• Some particles containing two or more polymeric phases include core/shell particles, core/shell particles with shell phases incompletely encapsulating the core or core/shell particles with a multiplicity of cores or interpenetrating network particles.
• Sequential polymers may be prepared by conventional emulsion polymerization processes, preferably by well-known multi-stage emulsion polymerization, in which at least two stages differing in composition are formed in a sequential fashion. Such a process usually results in the creation of at least two mutually incompatible polymer compositions, thereby resulting in the formation of at least two phases.
• Each stage of the sequential polymer particles may contain chain transfer agents and surfactants, as well as other additives necessary to perform the polymerization reaction.
• U.S. Pat. No. 4,814,373 may be consulted for further general and preferred details used for preparing sequential polymers by emulsion polymerization techniques.
• Tg is the “glass transition temperature” of a polymer.
• the glass transition temperature is the temperature at which a polymer transitions from a rigid, glassy state at temperatures below its Tg to a fluid or rubbery state at temperatures above the Tg.
• the Tg of a polymer is typically measured by differential scanning calorimetry (DSC) using the mid-point in the heat flow versus temperature transition as the Tg value. A typical heating rate for the DSC measurement is 20° C./minute.
• DSC differential scanning calorimetry
• a typical heating rate for the DSC measurement is 20° C./minute.
• the Tg of various homopolymers may be found, for example, in The Polymer Handbook, edited by J. Brandrup and E. H. Immergut, Interscience Publishers.
• the Tg of a polymer is calculated by using the Fox equation (T. G. Fox, Bull. Am. Physics Soc., Vol. 1, issue no. 3, page 123, 1956).
• (meth)acrylate refers to either acrylate or methacrylate.
• “Molecular weight” may be defined in several different ways. Synthetic polymers are almost always a mixture of many different molecular weights, i.e., there is a “molecular weight distribution”, or “MWD”. For a homopolymer, members of the distribution differ in the number of monomer units which they contain. This idea also extends to copolymers. Given that there is a distribution of molecular weights, the most complete characterization of the molecular weight of a given sample is the determination of the entire molecular weight distribution. This characterization is obtained by separating the members of the distribution and then quantitating the amount of each that is present. Once this distribution is at hand, there are several summary statistics, or moments, which can be generated from it to characterize the molecular weight of the polymer.
• Mw weight average molecular weight
• Mn number average molecular weight
• Mi molar mass of the ith component of distribution
• Wi weight of the ith component of distribution
• Ni number of chains of the ith component
• Mw and Mn are typically computed from the MWD as measured by Gel Permeation Chromatography (“GPC”).
• Hydrophobic monomer as used herein, means a monomer having a Hansch ⁇ value of at least 3.5.
• hydrophobic monomers suitable for use in the present invention are monomers having a Hansch ⁇ value of at least 3.5.
• hydrophobic monomers include 2-ethylhexyl acrylate, butyl methacrylate, stearyl methacrylate, cetyliscosyl methacrylate and lauryl methacrylate.
• the vinyl aromatic monomers which may be utilized are preferably selected from styrene and various substituted styrenes.
• exemplary substituent groups include 2-bromo, o-bromo, p-chloro, o-methoxy, p-methoxy and methyl.
• Many conventional traffic paints omit styrene monomers from their formulations because of styrene's known tendency to degrade when exposed to the UV radiation to which traffic paints are typically subjected.
• these monomers may be successfully employed to enhance the adhesive properties of the present invention on oily road surfaces.
• the remainder of the monomer mixture may include at least one or more of the following hydrophilic monomers having a Hansch ⁇ value of less than 3.5.
• hydrophilic monomers include:
• copolymerizable ethylenically-unsaturated acid monomers in the range of from 0.1% to 10%, by weight, based on the total weight of the polymer solids, of a acrylic acid, maleic acid, monomethyl itaconate, monomethyl fumarate, monobutyl fumarate, maleic anhydride, 2-acrylamido-2-methyl-1-propanesulfonic acid, sodium vinyl sulfonate, phosphoethyl methacrylate, and combinations thereof may be used.
• the polymers used in the inventive composition have a Tg in the range of from ⁇ 25° C. to 25° C., preferably in the range of ⁇ 10 20 C. to 10° C. Most preferred are polymers having a Tg of from ⁇ 5° C. to 5° C.
• the polymers used in the present invention have a low molecular weight.
• the term “low” identifies polymers having a weight average molecular weight (“Mw”), as measured by conventional GPC techniques, in the range of from 1000 to 200,000, most preferably in the range of 1000 to 100,000.
• the polymer of the inventive composition may be a dispersed polymer having polymer particles dispersed in an aqueous evaporable carrier or it may be either a water soluble polymer, a water reducible polymer, a mixture of the water soluble and water reducible polymers in the aqueous evaporable carrier, or a mixture of the dispersed, water reducible and water soluble polymers in the aqueous evaporable carrier.
• the polymerization techniques which may be used for preparing the polymers of the present invention are well known in the art.
• the polymers may be prepared by aqueous solution polymerization or by emulsion polymerization. Emulsion polymerization is preferred. Either the thermal or redox initiation processes may be used.
• Polymers of alpha-beta ethylenically unsaturated monomers and their esters, especially the acrylic and methacrylic esters, are preferably prepared by processes described in “Emulsion Polymerization of Acrylic Monomers: May 1966”, a publication of the Rohm and Haas Co., Phila. Pa.
• the polymerization process is typically initiated by conventional free radical initiators, such as, for example, hydrogen peroxide, benzoyl peroxide, t-butyl hydroperoxide, t-butyl peroctoate, ammonium and alkali persulfates, typically at a level of 0.05 to 3.0 percent by weight, based on the total weight of the monomer.
• free radical initiators such as, for example, hydrogen peroxide, benzoyl peroxide, t-butyl hydroperoxide, t-butyl peroctoate, ammonium and alkali persulfates
• Redox systems using the same initiators coupled with a suitable reductant such as, for example, sodium bisulfite may be used at similar levels.
• Suitable chain transfer agents include halo-organic compounds, such as carbon tetrabromide and dibromodichloromethane; sulfur containing compounds such as alkylthiols including ethanethiol, butanethiol, tert-butyl and ethyl mercaptoacetate, as well as aromatic thiols; or various other organic compounds having hydrogen atoms which are readily abstracted by free radicals during polymerization.
• Additional chain transfer agents include, but are not limited to, butyl mercaptopropionate, isooctyl mercaptopropionic acid, bromoform, carbon tetrachloride and alkyl mercaptans, such as, 1-dodecanthiol, t-dodecyl mercaptan and n-dodecyl mercaptan (“nDDM”). Mercaptans are preferred with nDDM being the most preferred.
• a water reducible or water soluble polymer may be prepared directly in water if the monomer mix is water soluble.
• a water miscible solvent may be used, in which case water may be included in the polymerization mixture or is added after the polymerization process is complete. Water soluble or water reducible polymers produced this way may be blended together with dispersed polymers if so desired.
• the drying time of the newly applied traffic paint may be accelerated in many ways.
• the paint may contain a polyfunctional amine together with an anionically stabilitzed latex and a volatile base.
• polyfunctional polyamines include p(OXEMA), p(vinylamine) and polyethyleneimine.
• latexes containing pendant amine functionality derived from a number of methods, including copolymerizing amine functional monomer into the latex polymer or subsequently reacting a latex polymer to yield amine groups attached to the latex polymer may be used to accelerate the drying of a traffic paint.
• a polyfunctional amine When a polyfunctional amine is used it may be present in the paint or it may be added as a separate component before, during or after the paint is applied.
• U.S. Pat. No. 5,804,627 provides additional information on the use of polyfunctional polyamines in traffic paint.
• U.S. Pat. No. 5,922,398 provides additional information on the use of latex polymers containing pendant
• Absorbers may be used to accelerate the drying of traffic markings.
• the absorbers should be able to absorb and/or adsorb small molecules like water, ammonia, C1-C6 alkylamines, C1-C6 alcohols, and mixtures thereof.
• Examples of absorbers include, but are not limited to, ion exchange resins, hollow sphere polymers, molecular sieves, organic super absorbing polymers, inorganic absorbents, porous and non-porous carbonaceous materials and mixtures thereof.
• U.S. Pat. No. 5,947,632 provides additional information on the use of absorbers in traffic paint.
• Drying of traffic paint may also be accelerated by contacting the paint with an acid during application of the paint.
• the acid may be in the form of an acid solution, an acid containing powder or glass beads coated with an acid.
• the acid may be applied to the paint or sprayed into a spray mist of the paint during the application of the paint.
• U.S. Pat. No. 5,544,972 should be consulted for further details on this method. Any of the previously identified methods used to accelerate the drying of traffic paint may be combined as required by the application.
• additional components may be added to the composition.
• additional components include, but are not limited to, thickeners; rheology modifiers; dyes; sequestering agents; biocides; dispersants; pigments, such as, for example, calcium carbonate, talc, clays, silicas and silicates; fillers, such as, for example, glass or polymeric microspheres, quartz and sand; anti-freeze agents; plasticizers; adhesion promoters; coalescing agents; wetting agents; waxes; surfactants; slip additives; defoamers; preservatives; corrosion inhibitors and anti-flocculants.
• a layer of aqueous traffic paint is applied to the surface of an oily roadbed.
• the traffic paint may be applied using application techniques known in the art, such as, for example, by spraying onto the road surface by means such as truck mounted spray guns where the traffic paint is forced through a spray nozzle(s) from an air pressurized tank or by means of an airless pump. If desired, the traffic paint may be hand applied by means of a paint brush or paint roller.
• the wet thickness of the layer of aqueous traffic paint generally varies from 100 ⁇ m to 3000 ⁇ m, and is preferably from 350 ⁇ m to 1000 ⁇ m.
• the method of the present invention may include dropping glass beads on the newly applied traffic paint before it is completely dry.
• the glass beads which adhere to the top of the traffic paint act as light reflectors. If glass beads are not used, the traffic markings would be difficult to see under night and wet weather conditions. As a result, nearly all traffic markings today contain some amount of glass beads, usually in the range of 0.72 to 2.9 kilograms per liter of paint.
• the application of glass beads may be by any conventional method, such as by dropping them at a selected rate out of a hopper which is positioned in close proximity to the traffic paint applicator. The glass beads are dropped onto the freshly applied traffic paint while the paint is still wet tacky. This allows the glass beads to adhere to the top surface of the traffic paint as it dries.
• p(OXEMA) is poly(oxazolidinoehtylmethacrylate). It may be prepared according to the procedure shown in EP 0950763A1.
• Monomer mixture 3 in grams (g) DI water 800 Surfactant * 31.5 2-ethylhexyl acrylate 1066 Methylmethacrylate 908 methacrylic acid 26 n-dodecylmercaptan 20.0
• Monomer mixture 4 in grams (g) DI water 800 Surfactant * 31.5 2-ethylhexyl acrylate 694 Methylmethacrylate 680 Styrene 200 methacrylic acid 26 n-dodecylmercaptan 20.0
• Monomer mixture 5 in grams (g) DI water 800 Surfactant * 31.5 2-ethylhexyl acrylate 1000 Methylmethacrylate 774 Styrene 200 methacrylic acid 26 n-dodecylmercaptan 20.0
• Monomer mixture 7 in grams (g) DI water 750 Sodium lauryl sulfate (28%) 31.5 2-ethylhexyl acrylate 950 Methylmethacrylate 1024 methacrylic acid 26 n-dodecylmercaptan 20.0
• Monomer mixture 8 in grams (g) DI water 800 Surfactant * 31.5 2-ethylhexyl acrylate 1000 Methylmethacrylate 674 Styrene 300 methacrylic acid 26 n-dodecylmercaptan 20.0
• Rhoplex Fastrack® 2706 commercially available from Rohm and Haas Company, Philadelphia, Pa., U.S.A..
• Rhoplex Fastrack® 3427 commercially available from Rohm and Haas Company, Philadelphia, Pa., U.S.A.
• Traffic Paints 1 through 8 and Comparative Traffic Paints C 1 through C 6 were prepared according to the following formulations. The ingredients were added in the given order. The ingredients of Part I (A through I) were added sequentially under high shear agitation and then mixed for 15 minutes. Part II ingredients (J through O) were then added sequentially, at an agitation speed necessary to maintain a deep vortex. Once all ingredients were added, the formulation was mixed for 15 minutes at a viscosity of 80 to 85 KU (Krebs Units).
• H means TiPure ® R-900 titanium dioxide supplied by E. I. duPont de Nemours & Co., Wilmington, DE.
• I means Omyacarb ® 5, ground natural calcium carbonate, supplied by Omya, Inc., Proctor, VT. J means methanol.
• K means Texanol ®, an ester alcohol supplied by Eastman Chemicals, Kingsport, TN.
• L means benzophenone (30% in methanol).
• M means Acrysol ® SCT-275, a rheology modifier supplied by Rohm and Haas Co., Phila., PA.
• N means Natrasol ® 250 HR supplied by Aqualon, Inc., Wilmington, DE.
• O means water.
• Oil Patch Adhesion Using a standard commercial grade automotive motor oil, a 6“ ⁇ 12” oil patch is brushed onto the surface of a test section of a concrete based road surface. After waiting for approximately 1 hour, the traffic paint to be tested is applied by spraying it as a line positioned transverse to the direction of traffic flow. The test lane is then opened up for traffic approximately 1 hour after paint application. At selected time intervals (typically from 1 to 6 weeks), the paints are evaluated for adhesion loss by being rated on a scale of from 0 to 10, with 10 representing no loss of adhesion, 0 representing total loss of adhesion and the values in between used to indicate varying degrees of adhesion loss.
• Cross-Hatch Adhesion 6“ ⁇ 12” ⁇ 1 concrete blocks are formed by curing Portland Type I cement in polypropylene molds. The blocks are allowed to cure for a minimum of 1 month. Onto the smooth facing of each test block is applied approximately 3 grams of a standard commercial grade automotive motor oil, then rubbing evenly to apply a uniform film. After 24 hours, the test paint to be evaluated is applied onto the oily surface by using a 10 mil drawdown bar, thus forming a 7 mil wet film. After the paint is allowed to dry for 24 hours, a razor is used to scribe a grid pattern of 100 squares, each of which approximately 2 mm by 2 mm in size.

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• Chemical & Material Sciences (AREA)
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• Materials Engineering (AREA)
• Wood Science & Technology (AREA)
• Organic Chemistry (AREA)
• Architecture (AREA)
• Civil Engineering (AREA)
• Structural Engineering (AREA)
• Paints Or Removers (AREA)
• Road Signs Or Road Markings (AREA)
• Application Of Or Painting With Fluid Materials (AREA)

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• 2003
  • 2003-03-31 DE DE60319763T patent/DE60319763T2/de not_active Expired - Lifetime
  • 2003-03-31 AT AT03252014T patent/ATE389699T1/de not_active IP Right Cessation
  • 2003-03-31 ES ES03252014T patent/ES2302899T3/es not_active Expired - Lifetime
  • 2003-03-31 EP EP03252014A patent/EP1352931B1/en not_active Expired - Lifetime
  • 2003-04-01 US US10/404,483 patent/US20030194486A1/en not_active Abandoned
  • 2003-04-03 MX MXPA03002951A patent/MXPA03002951A/es active IP Right Grant
  • 2003-04-07 CA CA002424640A patent/CA2424640C/en not_active Expired - Fee Related
  • 2003-04-08 JP JP2003104438A patent/JP4181911B2/ja not_active Expired - Fee Related
  • 2003-04-10 KR KR1020030022673A patent/KR100985547B1/ko active IP Right Grant

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