WO1998001237A1

WO1998001237A1 - Method of applying a road marking composition

Info

Publication number: WO1998001237A1
Application number: PCT/US1997/009474
Authority: WO
Inventors: Bradley J. Helmer; Roger W. Bergman
Original assignee: The Dow Chemical Company
Priority date: 1996-07-08
Filing date: 1997-06-02
Publication date: 1998-01-15
Also published as: ID17941A

Abstract

A road marking composition is applied by applying (1) an aqueous dispersion of a film-forming binder and (2) a polyamine. The process of the invention provides rapid drying, and the dried composition is not prone to smearing.

Description

METHOD OF APPLYING A ROAD MARKING COMPOSITION

The invention relates to a method of applying a road marking composition. Environmental considerations make the use of solvent-based paints increasingly less desirable. Water-based paints are the main alternative to solvent-based paints. However, conventional aqueous compositions have the disadvantage that in actual practice the drying time is both uncontrollable and unacceptably long, depending on the weather conditions and the state of the road surface. A short drying time is essential in that after application of the road marking composition, the road must be reopened to traffic as quickly as possible.

It would be desirable to have a method by which water-based paints, or road markings, are hard and nontracking within a very short time, for instance within about 15 minutes after application. It would also be desirable to have a road painting method such that the road marking composition could be successfully applied to a wet road surface, such as when there is some light rain or snow. As a result, the progress and scheduling of this kind of road work could be better controlled.

The invention is such a desired method, characterized in that an aqueous road paint composition based on a dispersion of a film-forming binder having a minimum film-forming temperature of 0°-60°C and 30-80 percent by volume of filler, calculated on the total volume of solids in the paint composition, is applied to the road surface and contacted with a polyamine.

The process of the invention employs a paint and a polyamine. The paint employed comprises a filler, which includes a pigment, and a dispersion of a film-forming binder.

For the marking composition, or paint, use may generally be made of any suitable dispersion of a film- forming binder of the desired minimum film- forming temperature, for instance aqueous dispersions of polyvinyl acetate, styrene-butadiene polymer, styrene-acrylate polymer or poly (meth) acrylate . These dispersions may include polymers which contain 0-30 percent by weight of a different copolymerized monomer such as acrylic acid, methacrylic acid, aleic acid, acryla ide or hydroxyethyl acrylate. The minimum film-forming temperature of the aqueous dispersion is preferably 0°-30°C. The dispersions are commercially available from, for example, any of several latex suppliers.

The polyamine can be a nonpolymeric , oligomeric or polymeric polyamine in cationic form or in a form which becomes cationic when in contact with the paint employed. Preferably, the polyamine is a polycationic polyamine having at least 3 amino groups, more preferably at least 4 and most preferably at least 5 amino groups. Preferred polyamines have at least 2 mer units, and preferably have at least 5 mer units. Preferably, the polyamine is sprayable, and more preferably is soluble in water so it can be applied as an aqueous solution. The polyamine is employed in an amount which is sufficient to harden the substrate paint. Preferably, the amount is such that the paint has a no track time {ASTM D711-84) of less than or equal to about 10 minutes after the polyamine is contacted with the paint. More preferably, the amount is such that the no track time is not more than about 5 minutes. Most preferably, the amount is such that the no track time is not more than about 3 minutes. Typically, the amount of polyamine employed is from 0.1 to 2 weight percent, and preferably is from 0.2 to 1 weight percent, based on the weight of the paint . The polyamine is preferably applied in the form of a solution of the polyamine in a solvent, which solvent preferably is water. The concentration of the polyamine in the solution may vary widely, but typically is from 10 to 30 weight percent, and preferably is 15 to 25 weight percent.

Examples of suitable polyamines include: polyimines in their base form or in their partially or fully neutralized (protonated) form; polymeric amines having pendant amine functionality as described in U.S. Patent 4,119,600 at column 4, line 67 through column 7, line 39, including amino functional (meth) acrylates such as dimethylaminoethyl methacrylate (DMAEM),and these polymeric amines in their partially or fully protonated form; and polyamines and polyquaternary ammonium salts such as described in the Encycl opedia of Polymer Science and Engineering, Vol. 11, pages 489-507 (1985), including those based on polyacrylamide and those based on epichlorohydrin. The teachings of the references cited in this paragraph are incorporated herein by reference.

Suitable polyimines for use in this invention include, for example, polyethyleneimines and polypropylenimines , desirably with a molecular weight of at least about 150, preferably with a molecular weight of at least about 400, and more preferably with a molecular weight of at least about 700. The molecular weight of the polyimine suitably is no greater than about 1,000,000; desirably, no greater than about 200,000; more desirably no greater than about 50,000; preferably no greater than 10,000; and more preferably no greater than about 2,000. When higher molecular weight polyimines are employed, the viscosity increases and the compositions are more difficult to use. Preferred polyimines include polyethyleneimine (PEI) that is made up of about 35 ethylenimine (El) units, with the result that it has a molecular weight of about 2000. The material is available from BASF as POLYMIN™ G- 35, CAS No. 9002-98-6, and is supplied as a 50 percent solution in water. Other commercially available PEI ' s are those with an average of 12 El units, POLYMIN¹¹¹ FG, and 20 El units, POLYMIN™ G-20. The molecular weights of these PEI ' s have been determined by standard gel permeation chromatographic (GPC) characterization based on narrow distribution polyethylene glycol and polyethylene oxide calibration standards, which yields a number average molecular weight . The molecular weights of the PEI ' s have also been determined by light scattering techniques, which yield weight averages in close agreement with the GPC result. This indicates that there is a high degree of monodispersity and a narrow Gaussian molecular weight distribution for these PEI ' s . The polyamines referred to above are known to the man skilled in the art and need not be further described here.

According to the invention the paint composition to be applied also contains 30-80, preferably 45-65 percent by volume of filler, calculated on the total volume of solids in the paint composition. Examples of suitable fillers include pigments such as titanium dioxide, chrome yellow, chrome orange, phthalocyanine blue, chromium oxide and iron oxide, and extenders such as solid polymeric additives, silicates, silicon dioxide, talc, barium sulfate, calcium carbonate, silicon carbide and corundum, and mixtures of the above fillers. Organic pigments may also be employed in the filler. The marking composition may optionally contain still other additives, such as anti-foaming agents, wetting agents, emulsion stabilizers, liquid polymer additives and organic solvents. The marking composition generally has a viscosity of 40-140, preferably 60-100 Krebs units.

The method of the invention may be carried out in any convenient manner, for instance by first applying the marking composition to the road surface, preferably by spraying, and subsequently scattering the polyamine, for example, in solid form, onto it or applying a solution, preferably aqueous, of the polyamine to the wet marking composition, for instance by spraying. The aqueous marking composition may optionally be mixed with an aqueous solution of the polyamine, for instance with the aid of a 2-component mixing head, immediately before the marking composition is applied to the road surface. See, for example, WO 94/29391. After the marking composition has been applied to the road surface, the road marking may optionally be provided with the usual reflective spheres and anti-skid agents. These last-mentioned components may be provided before, during or after contacting the marking composition with the polyamine.

The process according to the invention may be applied to any type of road surface, such as concrete, asphalt, bitumen, bricks, cobblestones, tiles and steel plates. The marking composition is usually applied in a conventional layer thickness of about 100-1200 microns, preferably 200-600 microns (after drying) .

The invention is further described in the following examples, which are not to be construed as limiting the invention. All parts and percentages are by weight unless otherwise indicated. Latex Preparation

Into a glass lined stainless steel jacketed reactor was charged a mixture of 2139 g (70.6 parts active/100 parts monomer) of deionized water, 21.0 g (0.21 part) of 29.8 percent active polystyrene seed having an average diameter of approximately 280 angstroms, and 121 g (0.04 part) of a 1 percent solution of a chelating agent, VERSENOL^™' 120, in water. VERSENOL™ 120 is the trisodium salt of hydroxyethylenediaminetriacetate and is available from The Dow Chemical Company, Midland, Michigan 48640, United States of America. The reactor was purged with nitrogen and heated under agitation to 90°C. A mixture of 1575 g (52 parts) of methylmethacrylate, 30.3 g (1 part) of methacrylic acid, and 1423 g (47 parts) of butyl acrylate was added to the reactor over 200 minutes. 757 g (25 parts) of deionized water, 33.6 g (0.5 part) of a 45 percent solution of DOWFAX™ 2EP in water, 13.6 g (0.45 part) ammonium persulfate and 18.4g (0.17 part) of ammonium hydroxide was added to the reactor over 240 minutes. DOWFAX™ 2EP is the sodium salt of dodecylated sulfonated phenyl ether and is available from The Dow Chemical Company. The reactor was maintained at 90°C for the duration of the additions and for an additional 30 minutes. The resulting latex was a butyl acrylate/methyl methacrylate/acrylic acid (47/52/1) copolymer with a glass transition temperature of 20°C and a particle size of 2150 angstroms .

EXAMPLE 1

Paint was made according to the Wyoming White formulation using the latex prepared above. WYOMING WHITE

Initial Components Quant ty (σ)

Latex (50% Solids) 453.5 DOWICIL™ 75 0.5 DREW™ L-493 2.0 TAMOL™ 901 7.2 SURFYNOL™ CT-136 2.6 Ti-PURE™ R-900 100 0 NATRASOL™ 250 HBR 0.12 Water 24 0

Grind Components

OMYACARB™ 5 760 0

Letdown Components

DREW™ L-493 1.75 Methanol 30.0 DREW™ L-493 1.75 TEXANOL™ 23.0

Table 1 presents information related to various materials used in the Wyoming White formulation.

Table 1

Paint Preparation

The ingredients listed as initial components were added under mild agitation. After all of the initial components were added, the paint was mixed at low speed for 3 minutes . The speed of agitation was then increased and the ingredients listed as grind components were added. After all the grind components were added, the paint was ground at high speed for 4 minutes. The agitation was reduced and the ingredients listed as letdown components were added. After all the letdown components were added, the paint was mixed at moderate speed for 3 minutes .

The paint was cast as a 15 mil (375 microns) wet film, was sprayed with a fine mist of polyamine, and was then evaluated using the ASTM D711-84 No Track test. The values reported are an average of two determinations .

Samples 3,5,6 and 1? employ 0.5 equivalents concentrated HCl to partially protonate the polyamines before application. * *Comparatιve experiment - not an embodiment of the invention. The poly (dimethylaminoethylmethacrylate) (DMAEMA) used in Example 12 was produced as per Example C of U.S. Patent 4,119,600, using as the initiator system 4.19 g of tertiary- butyl hydroperoxide and 6.0 g of sodium formaldehyde sulfoxylate 2H_?0.

In the absence of any agglomerating spray, the paint required 24 minutes to pass the no track test. The use of a 20% solution of POLYMIN™ G-20 as a polyamine spray reduced the no track time to 4 minutes. This time was further reduced by using partially protonated POLYMIN™ G-20. Lower molecular weight PEI (E-100) performed similarly. However, partially protonated ethylenediamine did not reduce the no track time significantly. Other cationic polyamines gave no track times of 1-7 minutes.

No Track

This test was run as per ASTM D711-84. This test was run at 22°C and about 50 percent relative humidity (RH) . The time at which no paint adhered to the roller was recorded.

Shorter times indicate a faster drying paint and are preferred.

For the aqueous coating compositions of this invention, it is desirable that a pigment-containing formulation prepared from the composition have a no track time according to ASTM D711-84 of 10 minutes or less, while a preferred no track time is about

5 minutes or less, and even more preferred is a time of about 3 minutes or less .

Claims

1. A method of applying a road marking composition comprising (a) applying a road marking paint to a road surface, and (b) contacting the paint with a polyamine immediately prior to, during, or after applying the paint to the road surface.

2. The method of Claim 1 wherein the paint comprises a dispersion of a film-forming binder having a minimum film- forming temperature of 0°-60°C, and 30-80 percent by volume of filler calculated on the total volume of solids in the paint composition.

3. The method of Claim 2, wherein the dispersion of the film-forming binder has a minimum film-forming temperature of 0°-30°C.

4. The method of any of the preceding claims, wherein the polyamine has at least 3 amino groups.

5. The method of any of the preceding claims, wherein the polyamine is a polyethyleneimine .

6. The method of Claim 1, wherein the polyamine is a cationic polyamine, a cationic polyacrylamide, a cationic polyamine based on epichlorohydrin, a polyquaternary amine chloride, or a partially protonated poly(DMAEM).

7. The process of Claim 1 wherein the amine is a polyquaternary amine salt.

8. The method of any of the preceding claims, wherein the polyamine is in the form of an aqueous solution and the polyamine and the aqueous composition are mixed immediately prior to the application to the road surface.

9. The method of any of Claims 1-7, wherein the polyamine is on the surface of a bead which is applied to the road surface with the paint or before the paint is dried.

10. A method of applying a road marking paint composition comprising applying to a road surface an aqueous composition comprising a dispersion of a film-forming binder having a minimum film-forming temperature of 0°C to 60°C, and contacting the aqueous composition with from about 0.1 to 2.0 weight percent, based on the weight of the paint, of a polycationic polyamine having at least 5 amino groups and a molecular weight of at least about 150 in a manner such that the paint after being contacted with the polyamine has a no track time of not more than 3 minutes.