WO1994021960A1

WO1994021960A1 - Polyester road-marking paint compositions

Info

Publication number: WO1994021960A1
Application number: PCT/US1994/002761
Authority: WO
Inventors: Charles G. Ruggeri
Original assignee: Ruggeri Charles G
Priority date: 1993-03-15
Filing date: 1994-03-15
Publication date: 1994-09-29
Also published as: AU6365394A

Abstract

A polyester traffic paint composition is provided comprising an unsaturated polyester, a cross-linking agent, at least one pigment, a suspension agent, a wetting agent, vitreous beads and a catalyst. The catalyst comprises an aqueous dispersion of benzoyl peroxide encapsulated in an ionic region produced by a compound selected from the groups consisting of finely divided fumed silica, a sodium salt of a polymerized carboxylic acid and is fixed to the surface of the vitreous beads. In a further embodiment, a polyester traffic paint composition is provided, the formulation of which comprises a resin syrup containing an orthophthalic unsaturated polyester dissolved in a cross-linking agent, an isophthalic unsaturated polyester dissolved in a cross-linking agent, at least one pigment, a suspension agent, and a wetting agent, vitreous beads and the above-described catalyst. A method for road-marking utilizing said traffic paint compositions and a resin syrup for use in such compositions are also provided.

Description

POLYESTER ROAD-MARKING PAINT COMPOSITIONS

BACKGROUND OF THE INVENTION

This invention relates to road-marking paint compositions, and more particularly, to such compositions containing unsaturated polyester resins.

Polyester road-marking paints currently being utilized for roads and highways are two-component compositions consisting of a polyester resin and a catalyst, applied with specialized striping equipment. For enhanced visibility, reflective glass beads are dropped into the paint while it is still wet. Reflective polyester traffic paints are growing in popularity due to their low cost, handling and safety features, high reflectivity and the absence of any significant emission of volatile organic compounds during their application. However, polyester road-marking paints currently in use suffer from several drawbacks. Such polyester traffic paints are somewhat brittle, which reduces their adhesion to road surfaces and results in cracking and peeling of the paints because of their limited ability to expand and contract upon exposure to fluctuations in temperature and changing weather conditions. Additionally, the appli¬ cation of presently available polyester paints requires the use of special two-component dispensing equipment, since the catalyst must be kept separate from the polyester resin until roadway application. Further, wet or humid weather conditions hamper the application of polyester paints because of the moisture-sensitivity of the catalysts. Typically, polyester paints also exhibit a dry time of up to about 20 minutes from their appli¬ cation. This is a concern because, when the dry time exceeds one or two minutes, traffic must be cordoned off while the paint dries in order to prevent tracking of the paint. Traffic cordoning results in inconvenience to the public and creates potential hazards for the road crews. Laroche British Patent GB 2,208,078A discloses road-marking paints in which a fixing agent is used to adsorb a peroxide catalyst onto the surface of glass beads which are then incorporated into a polyester resin. Such a catalyst delivery system could potentially eliminate the need for two-component dispensing equipment since, theoretically, the catalyst can be added by dropping the catalyst-coated glass beads onto the resin. However, peroxide catalysts such as benzoyl peroxide and methylethyl ketone peroxide are highly volatile, flammable and potentially explosive. These highly toxic chemicals also tend to flake and chip from the glass beads after application. These characteristics combine to pose serious handling and performance problems which have effectively prevented commercial use of a polyester paint composition employing catalyst-coated beads according to the Laroche method.

Thus, the development of a reflective polyester traffic paint exhibiting enhanced flexibility, adhesion and durability, and which can be applied with minimal dry time and without the use of two-component dispensing equipment is highly desirable. Moreover, the discovery of a traffic paint exhibiting one or more of these advantages has been the object of considerable interest in the industry.

SUMMARY OF THE INVENTION

Among the several objects of the invention, therefore, may be noted the provision of a reflective polyester traffic paint with improved characteristics of flexibility, adhesion, and durability; the provision of such a paint composition which may be applied in wide-ranging climates and under dry, wet or humid conditions, and which may be applied without using specialised, two-component striping equipment and with a minimum of dry time; and the provision of a method for road-marking utilizing the aforementioned reflective polyester paint composition.

Briefly, therefore, the present invention is directed to a novel polyester traffic paint composition. The composition comprises an unsaturated polyester, a cross-linking agent, at least one pigment, a suspension agent, a wetting agent, vitreous beads and a catalyst comprising an aqueous dispersion of benzoyl peroxide encapsulated in an ionic region produced by a compound selected from the group consisting of finely divided fumed silica, a sodium salt of a condensed naphthalene sulfonic acid and a sodium salt of a polymerized carboxylic acid. The above-described catalyst is coated on the surface of the vitreous beads. The present invention is further directed to a polyester traffic paint composition the formulation of which comprises a resin syrup comprising an orthophthalic unsaturated polyester dissolved in a cross-linking agent, an isophthalic unsaturated polyester dissolved in a cross-linking agent, at least one pigment, a suspension agent, and a wetting agent, vitreous beads and a catalyst. The catalyst includes an aqueous dispersion of benzoyl peroxide encapsulated in an ionic region produced by a compound selected from the group consisting of finely divided fumed silica, a sodium salt of a condensed naphthalene sulfonic acid and a sodium salt of a polymerized carboxylic acid.

The invention also includes a method for road-marking. The method comprises the steps of coating reflective vitreous beads with an aqueous dispersion of benzoyl peroxide encapsulated in an ionic region produced by a compound selected from the group consisting of finely divided fumed silica, a sodium salt of a condensed naphthalene sulfonic acid and a sodium salt of a polymerized carboxylic acid and applying the coated vitreous beads to a resin syrup comprising an orthophthalic unsaturated polyester, an isophthalic unsaturated polyester, a cross-linking agent, at least one pigment, a suspension agent, and a wetting agent substantially simultaneously with application of the resin syrup to a roadway surface. The application of the coated beads to the resin syrup cures the resin syrup to form a road-marking on the roadway surface.

The invention is further directed to a curable resin syrup adapted for use in formulating a polyester traffic paint composition comprising an orthophthalic unsaturated polyester, an isophthalic unsaturated polyester, a cross- linking agent, at least one pigment, a suspension agent and a wetting agent.

Other objects and features will be in part apparent and in part pointed out hereinafter.

DESCRIPTION OF THE PREFERRED EMBODIMENT

In accordance with the present invention, a novel flexible, durable, reflective polyester traffic paint composition has been produced. The paint may be applied to roadways using either two-component or one-component striping equipment and may be applied under a wide range of weather conditions with a dry time of under one minute. The composition is formulated by preparing a resin combining an orthophthalic unsaturated polyester with an isophthalic unsaturated polyester. The polyester resin is then cured using a catalyst comprising a stabilized aqueous dispersion of benzoyl peroxide. The catalyst may either be directly combined with the resin during application of the resin to the roadway, or it may be coated onto glass beads which are then added to the resin. Surprisingly, incorporation of the benzoyl peroxide into such an aqueous dispersion does not adversely effect the cure rate of the polyester paint, and provides the advantage of permitting the peroxide to be coated onto glass beads without significant risk of releasing the volatile compound into the air due to flaking or chipping of the catalyst from the beads.

Unsaturated polyesters suitable for traffic paints are made by polyesterification of carboxylic acids or anhydrides with polyols, principally glycols, using techniques well understood in the art. Linear unsaturated polyester resins are fabricated from dicarboxylic unsaturated compounds such as maleic anhydride or fumaric acid, to which a saturated carboxylic acid or anhydride is added, in a ratio to produce approximately 3 to 10% unsaturation in the resulting polymer. These acid/anhydride compounds are then reacted with a glycol to form linear polyester chains. Typical glycols used include ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, diethylene glycol, dipropylene glycol, polyethylene glycol, and polypropylene glycol. A slight stoichio- metric excess of glycol over the acid/anhydride is preferably employed in preparing the unsaturated polyester.

Unsaturated polyester resins are prepared by combining the linear unsaturated polyesters discussed above with copolymerizable, cross-linking monomers such as styrene, p-methyl styrene, o-chlorostyrene, vinyl toluene, or methacrylic acid. Styrene or p-methyl styrene are preferred cross-linking agents for road- marking paints. This copolymerizable monomer is provided in an amount to constitute from about 20 to A5 percent by weight of the unsaturated polyester resin syrup. The unsaturated polyesters are dissolved in the free monomer together with inhibitors such as hydroquinone or p-tert- butyl catechol to prevent premature cross-linking. The resins also include promoters or accelerators, such as the organic salts of cobalt, e.g., cobalt naphthenate and cobalt octoate, or dimethyl aniline, which speed up the

.-activity of peroxide catalysts during curing of the polyeste It has been discovered in accordance with the invention that by combining an isophthalic unsaturated polyester with an orthophthalic unsaturated polyester, a polyester resin is produced which cures to form a traffic paint with superior flexibility, durability and adhesive characteristics. An improved traffic paint in accordance with the invention may be produced using a ratio of isophthalic to orthophthalic unsaturated polyester of about 90-10 to about 40-60. However, a ratio of about 70-30 isophthalic to orthophthalic is preferred for areas with temperatures ranging from 20°F to 120°F. In a particularly preferred embodiment of the present invention, a product such as Product No. 83-8320, a prepromoted isophthalic unsaturated polyester dissolved in 42% styrene, sold by Cargill Chemical Products of

Carpenterville, Illinois, is combined with a product such as Cargill Chemical Products' Product No. 83-8319, a prepromoted orthophthalic unsaturated polyester dissolved in 27% styrene. Pigments, suspension agents and other additives are incorporated into the polyester resin syrup to provide the base formulation for the polyester traffic paint. These components comprise 55 to 60% by weight of the base formulation. To produce a white paint, a prime pigment such as rutile titanium dioxide (TI0₂) is used, while a yellow pigment is used if a yellow traffic paint is being produced. Extender pigments are also added to provide body and reflectivity to the paint. Extender pigments include calcium carbonates, talcs, silicas, hydrated alumina and antimony oxide.

A suspension agent is used to maintain the pigments in a suspended state in the syrup. MP 200, a bentonite clay sold by United Catalyst, is a preferred suspension agent for use with the polyester traffic paints of the present invention. Preferably, the traffic paint also includes an ultra violet (UV) stabilizer to minimize discoloration and prolong the useful life of the paint, and a wetting agent to improve the bonding ability of the paint. Benzophenones and benzotriazoles are examples of useful UV stabilizers. A preferred UV stabilizer is Cyasorb UV- 5411, a 2-2-hydroxy-5-t-octylρhenyl benzotriazole, sold by Cyanamid V, used at 0.5% based on pigment by weight. Silanes such as Dow Chemical product No. Z-6020, are preferred as the wetting agent. Additionally, various resin modifiers, e.g., aromatic hydrocarbons and other components well known in this art, may be included in the resin syrup described above to promote adhesive strength or to enhance other specific properties to accommodate particular types of road surfaces, geographic climates, or other factors relevant to roadway marking.

It has been discovered that by using a benzoyl peroxide encapsulated in an aqueous dispersion in conjunction with the resin components discussed above, a paint is produced which has a dry time under one minute, which may be applied in wet or humid, in addition to dry, conditions, and which may be applied using one-component striping equipment without fear of releasing significant levels of toxic and volatile peroxide compounds into the air. This result is surprising since it was believed that incorporation of benzoyl peroxide into such an aqueous dispersion would significantly increase the necessary dry time for a polyester paint.

In general, the catalyst used in the preparation of the polyester paint of the instant invention comprises an aqueous dispersion of benzoyl peroxide encapsulated in an ionic region produced by a compound selected from the group consisting of finely divided fumed silica, a sodium salt of a condensed naphthalene sulfonic acid and a sodium salt of a polymerized carboxylic acid. A detailed description of organic peroxide compositions which fulfill the requirements of a catalyst for use in the subject invention is set forth in U.S. Patent No. 4,917,816, which is incorporated herein in full by reference. Preferred catalysts for use in the present invention are Abcure S-40-25 and Abcat 40 Type BPO Paste, sold by Abco Industries, Inc. of Roebuck, S.C. S-40-25 comprises a low viscosity, aqueous dispersion containing 40% benzoyl peroxide and 38% water. The balance of the catalyst composition includes — 1 to 7% of a compound that produces an ionic region about the peroxide particles in the dispersion, selected from fumed silica (e.g., Cab-o-sil brand silica, manufactured by Cabot Corp. of Boston, Mass.), a sodium salt of a condensed naphthalene sulfonic acid and a sodium salt of polymerized carboxylic acid; a defoamer such as DG-B, a silicone based defoamer manufactured by Dow Corning of Midland, Mich.; and 14-18% of an acidic inorganic salt. While the monosodium phosphate recommended in the '816 patent is acceptable for this purpose, preferably, a water soluble rehydrated salt or a water insoluble hydrated inorganic salt such as calcium sulfate dihydrate (gypsum) or aluminum trihydrate is used in order to adapt the catalyst for use in more humid conditions as well as to increase the useful storage life of the catalyst. Abcat 40 replaces the monosodium phosphate of S-40-25 with gypsum.

Vitreous beads such as reflective glass beads sold under the trademark of Hi-Vis™ beads by Potters Industries, Inc. are added to the polyester paint while the paint is still wet to make the paint highly reflective. To provide for proper admixture of the beads and resin and for optimum reflectivity of the roadway paint, the beads are preferably 20-80 U.S. mesh (150-850 microns). The beads are preferably used at a 10 lb. per gal. ratio if uncoated, and at a 24 lb. per gal. ratio if precoated with catalyst as discussed below. In one method for preparing the polyester paint of the present invention, the prepromoted isophthalic unsaturated polyester dissolved in cross-linking agent is mixed with the suspension agent. Prime and extender pigments, the wetting agent, and, optionally, other additives such as a UV stabilizer are ground into the resin mixture. Finally, a prepromoted orthophthalic unsaturated polyester dissolved in cross-linking agent is stirred into the resin mixture to complete the base formulation for the polyester paint.

In the course of the discovery of the invention it has been determined that unsaturated polyester resin blends of from 90/10 to 10/90 isophthalic polyester resin to orthophthalic polyester resin show adequate properties necessary for use as traffic paints. The dry times or cure rates of these paints range from 45 seconds to 210 seconds, with an optimum dry time of 60 seconds falling between the 70/30 and 60/40 ratios of iso/orthophthalic blends. Adhesion testing using an Elcometer Adhesion Tester Model No. 106 yielded a maximum adhesion for a 70/30 iso/orthophthalic blend of 420 lb/sq. in., at a recommended level of catalysts of 3-4% of the resin blend, although other levels also provide a suitable cure rate. However, increasing or decreasing the ratio of catalyst to resin resulted in a marked decrease in adhesion to a cement substrate.

For maximum adhesion with a low dry time a 70/30 ratio of iso/orthophthalic resin with 3% catalyst is preferred. Testing indicates that such a blend produces cured film within 60 seconds of application with excellent adhesion. In a preferred embodiment of the resin syrup, the isophthalic unsaturated polyester resin comprises about 25% by weight, the orthophthalic unsaturated polyester resin comprises about 16% by weight, and the balance of the ingredients make up about 59% of the weight of the resin syrup.

The aqueous dispersion of benzoyl peroxide may be applied to the base formulation as a spray in a two-component system with the catalyst applied at a ratio so that the catalyst comprises 2% to 4% by weight of the total composition of the paint, with 3% preferred. The exact proportions may be adjusted to take temperature and weather conditions into account. In a two-component system, the catalyst is sprayed into the base formulation immediately before the paint contacts the roadway surface to create the road marking.

Preferably, however, the catalyst (most preferably, Abcat 40 Type BPO paste) is applied as part of a one-component system by coating the catalyst onto the vitreous beads which are dropped into the polyester paint substantially simultaneously with application of the paint to roadway surfaces. The catalyst adhered to the beads thus contacts the polyester resin syrup and causes the resin to cure. For use in this manner, a 5 to 1 ratio of water to catalyst is employed. The bulk of the water is then subsequently removed after coating by heating the treated beads at temperatures ranging from 130-140°C for approximately 24-48 hours. In general, about 140 gallons of catalyst solution is used to coat 40,000 pounds of glass beads.

The beads are coated with the catalyst solution using either a batch or continuous process. For batch coating, a batch mixer is used together with a ribbon blender. A bulk of beads, e.g., 2000 lbs., is placed in the ribbon blender and heated to room temperature. The catalyst solution is coated onto the beads by slowly adding the catalyst to the ribbon blender and raising the temperature in the ribbon blender to approximately 140^βF. Its temperature is held at about 140°F for a time sufficient to ensure that all excess water has evaporated and that there is a uniform distribution of the catalyst coating on the beads.

The beads are coated in a continuous process by, for example, using a screw coater. In such a continuous process, the beads are placed in the screw coater and a steady flow of the catalyst solution is applied to the beads in the screw coater. The coated beads travel through the screw coater under heat so that any excess water will evaporate, and exit the screw coater after their catalyst coating has dried.

During roadway applications, uncoated glass beads are applied to the resin syrup at a rate of approximately 4 to 15 lbs. of beads per gallon of syrup and preferably 10 lbs. of beads per gallon of syrup. Catalyst coated beads are applied at a rate of approximately 20 to 28 lbs. of beads per gallon of syrup, and preferably, 24 lbs. per gallon.

The coated beads are dropped onto the resin syrup substantially simultaneously with application of the resin syrup to the roadway surface. Applied either as a one- or two-component paint composition, preferred embodiments of the paint of the present invention will dry to a no-tracking condition in one minute or less when applied at a temperature of 70 to 75°F, using a wet film thickness of 15 mil. At temperatures below 70°F, the paint should be heated or the amount of catalyst increased to maintain a no-tracking dry time of less than one minute. For example, a one minute dry time was maintained when the paint of the present invention was applied at an air temperature of 35°F by heating the resin syrup to 110 °F just before application.

The following examples illustrate the invention. EXAMPLE 1

Preparation of a Polyester Road-Marking Resin Syrup 42 gal. (382 lbs) of isophthalic unsaturated polyester resin dissolved in styrene and pre-promoted with an organic salt of cobalt as a cure accelerator (# 83-8320, Cargill Chemical Products, Carpenterville, IL.) were combined with 5 lbs. of a suspension agent (EZ 100 Tixogel), and mixed until fully dissolved. Pigments were then added in the following amounts - 6.53 gal. (225 lbs.) TI0₂ Kemira OR580, 14.62 gal. (330 lbs.) G-White

Hubercarb Q-6, and 16.06 gal. (350 lbs.) Silica Minex 4, and ground to a Hegman 4 minimum. A UV stabilizer (Cyabsorb UV-5411), silane, (Dow No. Z-6020), and bentonite clay (MP 200) were also incorporated into the resin syrup according to manufacturers' recommended instructions. Finally, 27 gal. (255 lbs.) of orthophthalic unsaturated polyester resin dissolved in styrene and pre-promoted with an organic salt of cobalt as a cure accelerator (#83-8319, Cargill Chemical Products, Carpenterville, IL) was stirred into the batch to produce a polyester road marking resin syrup.

EXAMPLE 2

One-Component Application of a Polyester Road-Marking Paint A polyester resin syrup was prepared as set forth in Example 1. 140 gal. of Abcat 40 were used to coat 40,000 lbs. of HI-VIS™ 20-80 U.S. mesh glass beads.

Using conventional one-component striper equipment (Kelly Creswell Co., Zenia, OH), the resin syrup and catalyst coated beads were loaded into the respective resin and bead tanks of the striper equipment and rated to apply a 15 mil thickness of paint and 24 lbs. of beads per gal. of resin. The resin syrup and catalyst coated beads were simultaneously applied to a concrete roadway at ambient temperatures and under clear skies. The resulting paint dried to a no-tracking condition within 55 seconds after application.

EXAMPLE 3

Performance Evaluation of Varying Ratios of Iso/Ortho Polyester Resins

The resin syrup of Example 1 was prepared as described therein, except that the ratio of isophthalic polyester resin (Cargill No. 8320) to orthophthalic polyester resin (Cargill No. 8319) was varied as reported in Table 1 in order to evaluate such resin performance characteristics as adhesive strength, dry time and paint flexibility.

Traffic paints containing the reported resin mixtures were tested for adhesive strength with and without the incorporation of glass beads (10-50 U.S. mesh glass beads applied at 10 lbs./gal.). Paints were allowed to dry on concrete surfaces at ambient tempera¬ tures and were tested using an Elcometer Adhesion Tester Model No. 106. The results are reported in Table 1. Also reported in Table 1 are the seconds required for the beaded resin mixtures to dry to a no-tracking condition.

As a final evaluation, the flexibility of the various mixtures was tested at a paint thickness of 15 mils (wet) by bending around mandrels of gradually decreasing diameter. Set forth in Table 1 are the maximum diameters at which each of the resin mixtures tested were found to bend without cracking.

TABLE 1

Adhesion (With & Without Glass Beads),

Dry Times and Bending Flexibility cif Resin Mixtures

Ratio of

Isophthalic/ Adhesion (In./lbs.)

Orthophthalic Bending

Polyester Without With Dry Flexibility

Resins Beads Beads Time (of 15 mils wet)

90/10 300 - 45 sec. Pass 2 1/2"

80/20 240 180 50 sec. Pass 2 1/2"

70/30 420 150 55 sec. Pass 1 5/8"

60/40 270 150 60 sec. Pass 1 1/2"

50/50 75 75 75 sec. Pass 1 1/2"

40/60 180 60 90 sec. Pass 5/8"

30/70 120 90 120 sec. Pass 5/8"

20/80 110 60 150 sec. Pass 1/4"

10/90 40 70 210 sec. Pass 1/8"

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained. As various changes could be made in the above methods and compositions without departing from the scope of the invention, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.

Claims

WHAT IS CLAIMED IS:

1. A polyester traffic paint composition comprising an unsaturated polyester, a cross-linking agent, at least one pigment, a suspension agent, a wetting agent, vitreous beads and a catalyst comprising an aqueous dispersion of benzoyl peroxide encapsulated in an ionic region produced by a compound selected from the group consisting of finely divided fumed silica, a sodium salt of a condensed naphthalene sulfonic acid and a sodium salt of a polymerized carboxylic acid, wherein the catalyst is fixed to the surface of the vitreous beads.

2. A polyester traffic paint composition as set forth in claim 1 wherein the unsaturated polyester comprises a mixture of an orthophthalic unsaturated polyester and an isophthalic unsaturated polyester.

3. A polyester traffic paint composition as set forth in claim 1 wherein the ratio of the isophthalic unsaturated polyester to the orthophthalic unsaturated polyester is about 70/30 by weight.

4. A polyester traffic paint composition as set forth in claim 1 wherein the catalyst comprises about 35 to about 45% benzoyl peroxide by weight.

5. A polyester traffic paint composition the formulation of which comprises a resin syrup comprising an orthophthalic unsaturated polyester dissolved in a cross-linking agent, an isophthalic unsaturated polyester dissolved in a cross-linking agent, at least one pigment, a suspension agent, and a wetting agent, vitreous beads and a catalyst comprising an aqueous dispersion of benzoyl peroxide encapsulated in an ionic region produced by a compound selected from the group consisting of finely divided fumed silica, a sodium salt of a condensed naphthalene sulfonic acid and a sodium salt of a polymerized carboxylic acid.

6. A polyester traffic paint composition as set forth in claim 5 wherein the ratio of the isophthalic unsaturated polyester to the orthophthalic unsaturated polyester is about 70/30 by weight.

7. A polyester traffic paint composition as set forth in claim 5 wherein the catalyst comprises about 35 to about 45% benzoyl peroxide by weight.

8. A method for road-marking comprising the steps of coating reflective vitreous beads with an aqueous dispersion of benzoyl peroxide encapsulated in an ionic region produced by a compound selected from the group consisting of finely divided fumed silica, a sodium salt of a condensed naphthalene sulfonic acid and a sodium salt of a polymerized carboxylic acid and applying the coated vitreous beads to a resin syrup comprising an orthophthalic unsaturated polyester, an isophthalic unsaturated polyester, a cross-linking agent, at least one pigment, a suspension agent, and a wetting agent substantially simultaneously with application of the resin syrup to a roadway surface and curing the resin syrup to form a road-marking on the roadway surface.

9. A method for road-marking as set forth in claim 8 wherein the ratio of the isophthalic unsaturated polyester to the orthophthalic unsaturated polyester contained in the resin syrup is about 70/30 by weight.

10. A method for road-marking as set forth in claim 16 wherein the catalyst comprises about 35 to about 45% benzoyl peroxide by weight.

11. A curable resin syrup adapted for use in formulating a polyester traffic paint composition comprising an orthophthalic unsaturated polyester, an isophthalic unsaturated polyester, a cross-linking agent, at least one pigment, a suspension agent and a wetting agent.

12. A curable resin syrup as set forth in claim 11 wherein the ratio of the isophthalic unsaturated polyester to the orthophthalic unsaturated polyester is about 70/30 by weight.