Reactive resin for paint

Abstract

The present invention is a composition comprising, based on the weight of the composition, a) from 15 to 98 weight percent of a monomer of Formula (1) where R1, R2, and X are defined herein; b) from 0.1 to 5 weight percent of a wax; and c) from 0.2 to 5 weight percent of an accelerator. The composition of the present invention is useful in 2K cold plastic traffic formulations.

Description

[0001] Reactive Resin for Paint Background of the Invention The present invention relates to a curable composition useful as a reactive resin in traffic road markings. Traffic road markings promote safe travel on streets and highways in a number of ways. For example, they may show which road to use, they may provide information about forthcoming road conditions, and they may indicate where passing is allowed. As roadways are rebuilt and refinished, more long-lasting markings are sought, even at a higher cost, since the cost of the marking is small relative compared to the cost of the overall job. Road markings are advantageously prepared using a two-component (2K) reactive formulation comprising one or more reactive monomers blended with an acrylic resin along with pigments and additives. A catalyst is added to the formulation just prior to road application to accelerate curing of the reactive monomers. These so-called “cold plastic” road marking formulations can be applied at a variety of film thicknesses, thereby providing significant dry film thickness flexibility. The resultant cured films readily adhere to concrete and asphalt, as well as glass beads and other retroreflective species. Coatings may be applied at even very cold temperatures and they are durable. Nevertheless, state-of-the-art 2K road marking technology suffers from the use of odoriferous, volatile, and often flammable monomers, such as methyl methacrylate and butyl acrylate, which require special care in handling and storing. Moreover, the application of these formulations in climates with relatively high temperatures causes the volatile monomers to evaporate, thereby adversely impacting the composition of the cured material. Accordingly, it would be an advantage in the art of road marking formulations to discover reactive monomers that overcome these shortcomings.

[0002] Summary of the Invention The present invention addresses a need in the art by providing a composition comprising, based on the weight of the composition, a) from 15 to 98 weight percent of a monomer of Formula 1: where R1is C1-C12-alkyl(OCH2CH2)m, benzyl, or phenyl; each R2is independently H or methyl; m is from 0 to 20; and X is either O or -O-(CH2)n-O-, where n is 2 or 3; b) from 0.1 to 5 weight percent of a wax; and c) from 0.2 to 5 weight percent of an accelerator. The composition of the present invention is useful in 2K cold plastic traffic formulations. Detailed Description of the Invention The present invention is a composition comprising, based on the weight of the composition, a) from 15 to 98 weight percent of a monomer of Formula 1: where R1is C1-C12-alkyl(OCH2CH2)m, benzyl, or phenyl; each R2is independently H or methyl; m is from 0 to 20; and X is either O or -O-(CH2)n-O-, where n is 2 or 3; b) from 0.1 to 5 weight percent of a wax; and c) from 0.2 to 5 weight percent of an accelerator. The concentration of the monomer of Formula 1 is preferably in the range of from 20 weight percent, to 90 or to 75 or to 70 weight percent, based on the weight of the composition. Preferably, the monomer of Formula 1 is represented by the following Formula 1a: where R1is C1-C6-alkyl, preferably methyl, ethyl, or isopropyl. Specific monomers of Formula 1 include the norbornyl methacrylate methyl 6-(methacryloyloxy)bicyclo[2.2.1]heptane-2- carboxylate (NBMA) and methyl 6-(acryloyloxy)bicyclo[2.2.1]heptane-2-carboxylate (NBA): methyl 6- 2-carboxylate (NBMA) methyl 6- 2-carboxylate (NBA) The monomer of Formula 1 can be prepared as illustrated in the following scheme: Dicyclopentadiene is with R1-acrylate or R1-methacrylate under thermal Diels-Alder 4 + 2 conditions to form an intermediate norbornyl alkyl ester (NBE), preferably a norbornyl methyl ester (NBME) where R1is methyl and R2is H; this intermediate is reacted with acrylic acid or methacrylic acid ( X = O) in the presence of a strong Lewis acid such as BF3-etherate and an inhibitor such as hydroquinone monomethyl ether (MEHQ) to form a mixture of products that include the monomer of Formula 1 and a norbornyl lactone byproduct, most notably hexahydro- 2H-3,5-methanocyclopenta[b]furan-2-one (NBL): O O hexahydro-2H-3,5- [b]furan-2-one (NBL) The lactone byproduct may be separated from the monomer of Formula 1 by suitable means such as column chromatography or distillation, or the blend may be used without further purification. Fortuitously, the lactone byproduct serves as a non-reactive plasticizer. The composition may further comprise one or more ancillary monoethylenically unsaturated monomers such as diethylene glycol methyl ether methacrylate, diethylene glycol methyl ether acrylate, diethylene glycol ethyl ether acrylate, polyethylene glycol alkyl ether methacrylate, n-butyl acrylate, ethyl acrylate, n-butyl methacrylate, isobutyl methacrylate, 2-octyl methacrylate, lauryl methacrylate, 2-ethylhexyl acrylate, and hydroxypropyl methacrylate. Alternatively, or additionally, the composition may further comprise a plasticizer other than the lactone byproduct such as tributyl O-acetyl citrate. Preferably, the composition further comprises one or more additional monomers or a plasticizer or both. The wax is one that creates a barrier to oxygen, thereby promoting the desired free radical polymerization. The concentration of the wax is preferably in the range of 0.2 or from 0.5 weight percent, to 3 or to 2 weight percent, based on the weight of the composition. The wax is preferably a paraffin wax, for example Hywax 5603 paraffin wax. The concentration of the accelerator is preferably in the range of from 0.3 or from 0.5 or from 0.7 weight percent, to 4 or to or to 3 or to 2 weight percent, based on the weight of the composition. Aromatic amines are an example of a suitable class of accelerators, examples of which include N,N-bis(2-hydroxypropyl)-p-toluidine, N,N-dimethyl-p-toluidine, N-(2- hydroxyethyl)-N-methyl-4-toluidine, and N-phenyldiethanolamine. A cobalt salt such as cobalt(II) 2-ethylhexanoate can also be used an accelerator. Preferably, the composition further comprises an acrylic, styrene-acrylic, or urethane-acrylic resin having a Tgas calculated by the Fox equation in the range of from 30 °C or from 40 °C, to 120 °C or to 100 °C or to 80 °C or to 60 °C. Acrylic resins are preferred. The resin, which is a solvent-free solid, is advantageously prepared by solution polymerization of one or more suitable monomers, followed by solvent removal, by any of several methods including those well known in the art. Examples of suitable monomers include styrene, acrylate, or methacrylate monomers such as methyl methacrylate, styrene, ethyl acrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, benzyl methacrylate, and isobornyl methacrylate. Commercial examples of suitable resins include PARALOID™ B-56 Acrylic Polymer, PARALOID™ B-66 Acrylic Polymer, and PARALOID™ B-99N Acrylic Polymer. (PARALOID is a trademark of The Dow Chemical Company or its Affiliates.) The concentration of the resin is preferably in the range of from 5 or from 15 or from weight percent, to 40 or to 35 weight percent, based on the weight of the composition. The composition advantageously further comprises an inhibitor such as 2,6-di-t-butyl-4- methylphenol, 2,4-dimethyl-6-t-butylphenol, or MEHQ. The composition of the present invention is a precursor to a paint formulation suitable for traffic marking. In some embodiments, the composition is a non-volatile, low-odoriferous precursor. The paint formulation comprises the composition of the present invention and an opacifying pigment such as TiO2, a rheology additive, an oxidant such as benzoyl peroxide, and a filler including CaCO3, silica, and glass beads. Surprisingly, it has been discovered that tack-free coatings from the composition can be formed in less than 30 minutes. Examples Intermediate Example 1 – Preparation of Blend of NBMA and NBL or Pure NBMA A 500-mL three-neck flask was charged with methacrylic acid (114 g), MEHQ (1.51 g), BF3·Et2O (4.10 mL) and 1,4-dioxane (60 mL). The flask was fitted with a condenser and an addition funnel containing NBME (100 g) in dioxane (60 mL). The condenser was fitted with a tube to pass air through the reactor continuously. The reaction flask was heated at 100 °C with stirring, and the NBME solution was added dropwise from the addition funnel. Once half of the NBME solution was added, another portion of BF3·Et2O (4.10 mL) was added to the reaction flask via syringe. After stirring the reaction mixture overnight at 100 °C, GCMS analysis was performed with the crude reaction mixture to monitor the reaction progress. Unconsumed NBME was converted to the desired product with addition of more BF3·OEt2. When all the NBME was consumed, the reaction flask was cooled to room temperature, and volatiles were removed in vacuo. The remaining brown solution in the flask was observed to contain at 66:34 w / w mixture of methyl 6-(methacryloyloxy)bicyclo[2.2.1]heptane-2-carboxylate (NBMA) and NBL. The crude reaction mixture was then diluted with diethyl ether and extracted with NaOH (1.0 M). The organic layer was then dried over MgSO4 and filtered. All volatiles were again removed in vacuo. The obtained mixture of NBMA and NBL was either used as is (Example 1) or NBMA was isolated as a pure compound by column chromatography using hexane / ethyl acetate (Examples 4-10) to afford the desired product, NBMA. Intermediate Example 2 – Preparation of Blend of NBA and NBL A 250-mL three-neck flask was equipped with a reflux condenser, an addition funnel, and a thermocouple was placed in a fume hood. The top of the addition funnel was equipped with a tube to pass air through the reactor continuously. The addition funnel was loaded with a solution of acrylic acid (28.5 mL), NBME (30 g), and MEHQ (45 mg). The flask was charged with 1,4-dioxane (40 mL) and heated to 90 °C with stirring. The reactor was then charged with BF3·OEt2 (2 mL) and the contents of the additional funnel were added over the course of 2 h. The internal reaction mixture was held at 86 °C for 16 h. The reaction was observed to achieve 100 % conversion to the monomer, methyl 6-(acryloyloxy)bicyclo[2.2.1]heptane-2-carboxylate (NBA, 65%), and the byproduct hexahydro-2H-3,5-methanocyclopenta[b]furan-2-one (NBL, 35 %). The reaction mixture was cooled, and volatiles were removed in vacuo. The crude reaction mixture was then diluted with diethyl ether and extracted with NaOH (1.0 M). The organic layer was then dried over MgSO4 and filtered. All volatiles were again removed in vacuo. The reaction mixture could be used without further purification (Examples 2 and 3) or further purified via silica-gel column chromatography (0-20 % ethyl acetate in hexanes) to afford the desired product, NBA. General Procedure for the Preparation of a Peroxide Cured Reactive Resin Formulation A. Reactive resins were prepared by adding triethylene glycol dimethacrylate; N,N-bis(2-hydroxypropyl)-p-toluidine; Hywax 5603 Paraffin wax; one or more monomers, including the monomer of Formula 1; plasticizer, if used, 2,6-di-t-butyl-4-methylphenol; and a stir bar to a glass vessel. Solid PARALOID B-66 or B-56 Acrylic Resin, if used, was slowly added with stirring. The vessel was loosely capped and heated to 60 °C until the mixture was completely homogenous (typically 0.5 h to 1 h). The reaction mixture was then cooled to room temperature. B. A portion of the reactive resin was added to a container, followed by addition of benzoyl peroxide (BPO). The mixture was agitated for 60 s, after which time a portion of the resin was applied as a 2-mm thick film to a substrate, and the tack-free time was recorded. General Procedure for Peroxide Cured Filled Paint Formulation Formulated pigmented paints were made in a Plastic Max 100 tall speed mixer cup using a DAC 150 Speed mixer. The reactive resin formulation of Part A was added along with Byk 410 Liquid Rheology Additive, TEGO Dispers 670 Dispersing Agent, and Bentone 27 Rheology Additive. The contents were mixed for 1 min at 2000 rpm. TiO2, calcium carbonate, and silica were added, and the contents were mixed with a wooden stir stick before being placed in speed mixer for 5 min at 1600 rpm. Paints were allowed to set overnight to observe any thickening or separation. Benzoyl peroxide (BPO) was added to the formulated pigmented paint in a vessel equipped with a temperature probe, thereby generating heat. Tack-Free Time Measurements Tack-free time is the time elapsed from the addition of the BPO to the reactive resin or filled paint formulation to formation of a tack-free film, which is a film sufficiently cured so that observable amounts of resin did not transfer to a gloved finger after application of a light touch to the coating. Tack-free times were measured for formulations prepared using the monomer of Formula 1. Table 1 illustrates the reactive resin formulations. Form1 refers to the monomer of Formula 1, NBMA refers to methyl 6-(methacryloyloxy)bicyclo[2.2.1]heptane-2-carboxylate; NBA refers to methyl 6-(acryloyloxy)bicyclo[2.2.1]heptane-2-carboxylate; 2-EHA refer to 2-ethylhexyl acrylate; HPMA refers to hydroxypropyl methacrylate; NBL refers to hexahydro-2H-3,5- methanocyclopenta[b]furan-2-one; B-56 refers to PARALOID™ B-56 Acrylic Polymer; B-66 refers to PARALOID™ B-66 Acrylic Polymer; Wax refers to Hywax 5603 Paraffin Wax; and Citrate refers to tributyl O-acetyl citrate. All reactive resin formulations further include triethylene glycol dimethacrylate (2 wt%) as a crosslinker and N,N-bis(2-hydroxypropyl)-p- toluidine (1 wt %) as an accelerator.

[0003] Table 1 – Reactive Resin Formulations Ex. Form1 (wt%) Comonomer (wt%) Plast (wt%) Resin (wt%) Wax (wt%) Ex 1 NBMA(22) 2-EHA(29) / HPMA(5) NBL(13) B-56(27) (1) Examples 1-5 and 4 wt% for Examples 6-10, based on the weight of the reactive resin), and tack free times were measured. Each reactive resin formulations exhibited tack free times < 30 min and Shore D hardnesses at 24 h in the range of from 23 to 74. A passing Shore D hardness is in the range of from 20 to 80. Paints prepared using the reactive resins of Examples 5 to 10 are considered especially suitable for higher temperature environments, since none of these reactive resins contain volatile monomers. The paints formulated with these reactive resin formulations also exhibited tack-free times of less than 30 min and Shore D hardnesses at 24 h in the range of from 40 to 50.

Claims

Claims:

1. A composition comprising, based on the weight of the composition, a) from 15 to 98 weight percent of a monomer of Formula 1:where R1is C1-C12-alkyl(OCH2CH2)m, benzyl, or phenyl; each R2is independently H or methyl; m is from 0 to 20; and X is either O or -O-(CH2)n-O-, where n is 2 or 3; b) from 0.1 to 5 weight percent of a wax; and c) from 0.2 to 5 weight percent of an accelerator.

2. The composition of Claim 1 which further comprises a diethylenically unsaturated monomer, one or more ancillary monoethylenically unsaturated monomers, and a resin which is an acrylic, styrene-acrylic, or urethane-acrylic resin having a Tgas calculated by the Fox equation in the range of from 30 °C to 120 °C; and an inhibitor.

3. The composition of Claim 2 wherein the resin is an acrylic or styrene-acrylic resin, the diethylenically unsaturated monomer is triethylene glycol dimethacrylate, and the one or more ancillary monoethylenically unsaturated monomers is one or more monomers selected from the group consisting of diethylene glycol methyl ether methacrylate, diethylene glycol ethyl ether acrylate, diethylene glycol methyl ether acrylate, polyethylene glycol alkyl ether methacrylate, n-butyl acrylate, ethyl acrylate, n-butyl methacrylate, isobutyl methacrylate, 2-octyl methacrylate, lauryl methacrylate, 2-ethylhexyl acrylate, and hydroxypropyl methacrylate.

4. The composition of Claim 3 which further comprises a plasticizer; wherein the compound of Formula 1 is represented by the compound of Formula 1a:where R1is C1-C6-alkyl or benzyl; wherein the concentration of the wax is in the range of from 0.5 to 3 weight percent, based on the weight of the composition; and the concentration of the accelerator is in the range of from 0.5 to 3 weight percent, based on the weight of the composition; wherein the inhibitor is 2,6-di-t-butyl-4-methylphenol, 2,4-dimethyl-6-t- butylphenol, or hydroquinone monomethyl ether.

5. The composition of Claim 4 wherein R1is methyl, ethyl, or isopropyl, and the concentration of the compound of Formula 1a is in the range of from 20 to 70 weight percent, based on the weight of the composition.

6. The composition of Claim 5 wherein the concentration of the accelerator is in the range of from 0.5 to 2 weight percent, based on the weight of the composition, and the concentration of the wax is in the range of from 0.5 to 3 weight percent, based on the weight of the composition.

7. The composition of Claim 6 wherein the wax is a paraffin wax, and the accelerator is an aromatic amine.

8. The composition of Claim 7 wherein the one or more ancillary monoethylenically unsaturated monomers is one or more monomers selected from the group consisting of diethylene glycol methyl ether methacrylate, diethylene glycol ethyl ether acrylate, 2-ethylhexyl acrylate, and hydroxypropyl methacrylate, and wherein the plasticizer is hexahydro-2H-3,5- methanocyclopenta[b]furan-2-one or tributyl O-acetyl citrate.

9. The composition of Claim 8 wherein the resin is an acrylic resin having a Tgin the range of from 40 °C to 80 °C.

10. The composition of Claim 1 which further comprises an opacifying pigment, a rheology modifier, an oxidant, and a filler.

11. The composition of Claim 9 wherein the opacifying pigment is TiO2, the oxidant is benzoyl peroxide, and the filler is CaCO3, silica, or glass beads.

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