FLAME RETARDANT FORMULATIONS FOR WOOD COATING

Abstract

Flame retardant coating formulation in the form of an aqueous dispersion comprising a binder, particles of a brominated polymeric flame retardant; and particles of at least one of magnesium hydroxide and aluminum trihydrate, wherein the aqueous dispersion is substantially free of antimony oxide. A process for preparing the formulation and a method of reducing the flammability of wood and wood products by coating them with the formulation are also provided.

Claims

1. Flame retardant coating formulation in the form of an aqueous dispersion comprising a binder, particles of a brominated polymeric flame retardant (BFR); and particles of at least one of magnesium hydroxide and aluminum trihydrate, wherein the aqueous dispersion is substantially free of antimony oxide.

2. A flame retardant coating formulation according to claim 1, wherein the brominated polymeric flame retardant is tribromophenol end-capped brominated epoxy polymer of the formula Ia: ##STR00011## wherein m is the degree of polymerization.

3. A flame retardant coating formulation according to claim 1,wherein the brominated, polymeric flame retardant is brominated poly [styrene-co-butadiene].

4. A flame retardant coating formulation according to claim 1, wherein the brominated polymeric flame retardant is brominated polystyrene.

5. A flame retardant coating formulation according to claim 1, wherein the binder is an acrylate resin or a polyurethane resin.

6. A flame retardant coating formulation according to claim 1, comprising magnesium hydroxide.

7. A Flame retardant coating formulation according to claim 6, comprising : from 10 to 50 % by weight of water; from 10 to 35 % by weight of acrylate resin; from 5 to 25 % by weight of tribromophenol end-capped brominated epoxy polymer of the formula Ia; and from 2 to 10 % by weight of Mg(OH).sub.2.

8. A flame retardant coating formulation according to claim 6, comprising : from 10 to 50 % by weight of water; from 10 to 35 % by weight of acrylate resin; from 5 to 25 % by weight of brominated poly [styrene-co-butadiene]; and from 2 to 10 % by weight of Mg(OH).sub.2.

9. A flame retardant coating formulation according to claim 6, comprising : from 10 to 50 % by weight of water, from 10 to 35 % by weight of acrylate resin; from 5 to 25 % by weight of brominated polystyrene; and from 2 to 10 % by weight of Mg(OH).sub.2.

10. A flame retardant coating formulation according to claim 1, further comprising one or more of additives selected from dispersants, wetting agents, coalescing agents, defoamers, substrate wetting agents and rheology modifiers.

11. A flame retardant coating formulation according to claim 10, comprising a combination of nonionic dispersant and an anionic dispersant.

12. A flame retardant coating formulation according to claim 11, wherein the anionic dispersant is polyacrylate or polyphosphate salt.

13. A flame retardant coating formulation according to claim 12, wherein the anionic dispersant is polyacrylate sodium salt.

14. A flame retardant coating formulation according to claim 5, wherein the acrylic resin is self-crosslinking acrylic resin.

15. A flame retardant coating formulation according to claim 1, wherein the polyurethane resin is an aliphatic polyester polyurethane.

16. A flame retardant coating formulation according to claim 1, which is free of antimony oxide.

17. A process for preparing a flame retardant coating formulation for wood, comprising incorporating magnesium hydroxide or alumina trihydrate powder, and brominated polymeric flame retardant powder, into a water-based binder dispersion, wherein the coating formulation is substantially free of metal oxide synergist.

18. A process according to claim 17, wherein the binder is an acrylate resin or a polyurethane resin.

19. A process for preparing flame retardant coating formulation according to claim 17, comprising the steps of: 1a) adding magnesium hydroxide powder to water in the presence of a dispersant and optionally a wetting agent under high shear, to form Mg(OH).sub.2 aqueous dispersion: 1b) adding BFR powder to the Mg(OH).sub.2 aqueous dispersion, to form BFR/Mg(OH).sub.2 aqueous dispersion; 2) combining the BFR/Mg(OH).sub.2 aqueous dispersion with water-based acrylic resin to form the flame retardant coating formulation; wherein the process further comprises incorporating one or more of dispersants, wetting agents, coalescing agents, defoamers, substrate wetting agents and rheology modifiers into the Mg(OH).sub.2 aqueous dispersion, the BFR/Mg(OH).sub.2 aqueous dispersion, the water-based acrylic resin and/or the flame retardant coating formulation.

20. A process according to claim 17, wherein the magnesium hydroxide powder possesses particle size distribution of d.sub.50≤3 .Math.m and d.sub.90≤ 6 .Math.m; and the BFR powder possesses particle size distribution of d.sub.50<5 .Math.m and d.sub.90< 10, measured by laser diffraction.

21. A process according to claim 19, comprising adding nonionic dispersant to the water in step 1a and/or to the water based acrylic resin in step 2, and anionic dispersant to the water- based acrylic resin in step 2.

22. A method of reducing the flammability of wood and wood products, comprising applying the flame retardant aqueous dispersion of claim 1 to the surface of the wood or the wood product, to form a coating thereon.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0072] FIG. 1 is a bar chart showing the performance of coating formulations in the SBI test (FIGRA results).

[0073] FIG. 2 is a bar chart showing the performance of coating formulations in the SBI test (SMOGRA results).

[0074] FIG. 3 is graph showing heat release rates versus time curves recorded in a cone calorimeter while testing the burning properties of pine wood samples coated with BER/Mg(OH).sub.2-containing acrylic coatings and comparative coatings.

[0075] FIG. 4 is a graph showing heat release rates versus time curves recorded in a cone calorimeter while testing the burning properties of MDF samples coated with BER/Mg(OH).sub.2-containing polyurethane coatings and comparative coatings.

[0076] FIG. 5 is a graph showing heat release rates versus time curves recorded in a cone calorimeter while testing the burning properties of MDF samples coated with FR 122P/Mg(OH).sub.2-containing polyurethane coatings and comparative coatings.

EXAMPLES

[0077] Materials used for preparing the coating formulations are tabulated in Table 1 (FR means flame retardant):

TABLE-US-00002 Component GENERAL DESCRIPTION FUNCTION TexFRon® 4002 (ICL-IP) tribromophenol end-capped brominated epoxy polymer; MW= 1500-2500; PSD: d50<5 .Math.m; d90< 10 .Math.m; d99< 30 .Math.m brominated polymeric FR FR 122-P (ICL-IP) polystyrene-block-brominated polybutadiene-block-polystyrene brominated polymeric FR FR 803P (ICL-IP) brominated polystyrene brominated polymeric FR FR 1410 (ICL-IP) Decabromodiphenyl Ethane brominated FR FR 245 (ICL-IP) Tris(2,4,6-tribromophenoxy)-s-triazine brominated FR FR-20-100-S10 (ICL-IP) Mg(OH).sub.2; PSD: 1.1 .Math.m ≤d50 ≤ 1.4 .Math.m; 2 .Math.m ≤ d90 ≤ 4 .Math.m; BET: 8.5-11 m2/gr. PSD was determined by adding 0.15 grams of the powder in a dry 50 ml beaker, about 20 ml of isopropanol as a dispersion medium was added, the mixture was stirred using a magnetic stirrer for about 10-15 seconds and then dispersed in a 30 ultrasonic homogenizer (Elmasonic P) for 3 minutes, and the particle size distribution was measured by a laser diffraction scattering type particle size distribution measuring apparatus (Malvern Mastersizer 2000). FR ATH (SB-432, HUBER) Alumina trihydrate FR AC 2523 (Alberdingk Boley) Acrylic based copolymer dispersion Solid content: 47-49%; pH: 7.5-8.5; Viscosity: 500-4000 cps (Iso 1652) binder PU 9600VP (Alberdingk Boley) Aliphatic polyester polyurethane dispersion Solid content: 34-36%; pH: 7.5-8.5 Viscosity: 500-1500 cps (Iso 1652) binder Disperbyk®-2010 (BYK-Chemie GmbH) Aqueous emulsion of a structured acrylate copolymer with pigment-affinic groups dispersing, wetting agent LOPON® 800 ICL Polyacrylate, sodium salt Anionic dispersant Calgon® N ICL Polyphosphate, sodium salt Anionic dispersant BYK® 346 (BYK-Chemie GmbH) a solution of a polyether-modified polysiloxane Substrate wetting agent BYK® 093 (BYK-Chemie GmbH) a mixture of polysiloxanes and hydrophobic solids in polyglycol Defoamer BYK® 420 (BYK-Chemie GmbH) a solution of a modified urea Thickening, anti-settling agent PG (Gadot Chemicals) Propylene glycol coalescing agent NYACOL® A1550 Nyacol Nano Technologies 48% by weight aqueous dispersion of nano-sized antimony pentoxide FR synergist Supragil® WP (Solvay) Sodium Isopropyl Naphthalene Sulfonate wetting agent

Preparation 1 (Comparative)

Aqueous Dispersion of BER

[0078] Water (1313.5 g) was added to a mixing vessel, followed by addition of propylene glycol (869.5 g) and DISPERBYK 2010 (107 g) under stirring at a rate of 500 rpm (using R 1303 dissolver stirrer IKA with EUROSTAR power control-visc motor, IKA). BYK 093 (18.5 g) was slowly added. Next, TexFRon® 4002 (1369 g) was added slowly to the mixture, which was maintained under stirring to form homogeneous suspension. Lastly, BYK 420 (22.5 g) was added. Stirring was continued for an additional 30 minutes.

Preparation 2 (of the Invention)

Aqueous Dispersion of BER and Mg(OH).SUB.2

[0079] Water (1180.3 g) was added to a mixing vessel, followed by addition of propylene glycol (777.0 g), DISPERBYK 2010 (96.2 g) and BYK 093 (18.5 g) under stirring at a rate of 500 rpm (using R 1303 dissolver stirrer IKA with EUROSTAR power control-visc motor, IKA). Next, magnesium hydroxide (407.0 g of FR-20-100-S10 grade from ICL-IP) was introduced to the vessel under high shear rate at 10000 rpm. After the total amount of the magnesium hydroxide was added, the rate was increased to 20000 rpm for five minutes, to obtain a homogeneous suspension (high shear disperser was T 25 digital ULTRA-TURRAX instrument, equipped with S 25 KV - 25F dispersing tool, from IKA).

[0080] Lastly, TexFRon® 4002 (1221 g) was added slowly to the suspension, which was maintained under stirring (with the dissolver stirrer at 1000 rpm for twenty minutes) to afford the final suspension.

Example 1 (Reference)

Water-Based Acrylic Coating Formulation

[0081] Alberdingk 2523 (3116.80 g) was added to a mixing vessel, followed by the addition of DISPERBYK 2010 (32 g), BYK 346 (9.60 g) and BYK 093 (25.60) under stirring at a rate of 500 rpm (using R 1300 dissolver stirrer IKA with EUROSTAR power control-visc motor, IKA). After ten minutes, BYK 420 (16 g) was added. The mixture was maintained under stirring for 30 minutes.

Example 2 (Comparative)

BER-containing Acrylic Coating Formulation

[0082] Alberdingk 2523 (1644.8 g) was added to a mixing vessel, followed by the addition of DISPERBYK 2010 (32.0 g), BYK 346 (9.6 g) and BYK 093 (25.60) under stirring at a rate of 500 rpm (using R 1300 dissolver stirrer IKA with EUROSTAR power control-visc motor, IKA).

[0083] After ten minutes, the aqueous suspension of BER of Preparation 1 (1472 g) was added. The mixture was maintained under stirring to form a homogeneous formulation. Lastly, BYK 420 (16 g) was added. The mixture was maintained under stirring for 30 minutes.

Example 3 (Comparative; Based on US 10,626,289)

BER/APO-Containing Acrylic Coating Formulation

[0084] Alberdingk 2523 (1446.4 g) was added to a mixing vessel, followed by the addition of DISPERBYK 2010 (32.0 g), BYK 346 (9.6 g) and BYK 093 (25.6) under stirring at a rate of 500 rpm (using R 1300 dissolver stirrer IKA with EUROSTAR power control-visc motor, IKA).

[0085] After ten minutes, the aqueous suspension of BER of Preparation 1 (1472 g) was added. The mixture was maintained under stirring to form a homogeneous formulation. Next, a water-based dispersion of antimony pentoxide (APO; 198.4 g of 48% by weight aqueous dispersion of nano-sized Sb.sub.2O.sub.5; NYACOL A1550) was introduced to the vessel and stirred for five minutes. Lastly, BYK 420 (16 g) was added. The mixture was stirred for an additional 30 minutes.

Example 4 (Comparative)

BER/APO/Mg(OH).SUB.2.-Containing Acrylic Coating Formulation

[0086] Alberdingk 2523 (1280.0 g) was added to a mixing vessel, followed by the addition of DISPERBYK 2010 (32.0 g), BYK 346 (9.6 g) and BYK 093 (25.60) under stirring at a rate of 500 rpm (using R 1300 dissolver stirrer IKA with EUROSTAR power control-visc motor, IKA).

[0087] After ten minutes, the aqueous suspension of BER/Mg(OH).sub.2 of Preparation 2 (1638 g) was added. The mixture was maintained under stirring (starting at 1300 rpm, later switching to 700 rpm) to form a homogeneous formulation. Next, a water-based dispersion of antimony pentoxide (APO; 198.4 g of 48% by weight aqueous dispersion of nano-sized Sb.sub.2O.sub.5; NYACOL A1550) was introduced to the vessel and stirred for five minutes. Lastly, BYK 420 (16 g) was added. The mixture was maintained under stirring for 30 minutes.

Example 5 (of the Invention)

BER/ Mg(OH).SUB.2.-Containing Acrylic Coating Formulation

[0088] Alberdingk 2523 (1468.8 g) was added to a mixing vessel, followed by the addition of DISPERBYK 2010 (32.0 g), BYK 346 (9.6 g), BYK 093 (25.60) and Lopon 800 (16 g) under stirring at a rate of 500 rpm (using R 1300 dissolver stirrer IKA with EUROSTAR power control-visc motor, IKA). After ten minutes, the aqueous suspension of BER/Mg(OH).sub.2 of Preparation 2 (1638.4 g) was added. The mixture was maintained under stirring to form a homogeneous formulation. Lastly, BYK 420 (16 g) was added. The mixture was maintained under stirring for 30 min.

Example 6

Flammability Test of Coated Flame Retarded MDF Samples (SBI Test To Evaluate BER/Mg(OH).SUB.2.-Containing Acrylic Coatings)

[0089] The coating formulations of Examples 1 to 5 were evaluated according to the EN 13823 Single Burning Item (SBI) Test.

Preparation of the Test Specimen

[0090] A coating formulation was applied to an assembly consisting of two vertically positioned rectangular fire-retarded MDF plates (1500 mm x 1000 mm x 18 mm, and 1500 mm x 500 mm x 18 mm, produced by QINGDAO EONCRED WOOD CO., LTD), joined along their equal side to create a 90° corner. The coating was applied by a brush. Three coats were formed; each coat was dried at room temperature for at least four hours before the application of the next coat. Then the wood assembly was dried for sixteen hours prior to testing.

Test Procedure

[0091] Details of the SBI test can be found, for example, in http://virtual.vtt.fi/virtual/innofirewood/stateoftheart/datab ase/euroclass/euroclass.html. Briefly, the test was carried out in a small room (1=3 m × w=3 m × h=2.4 m), in which two vertical non-combustible boards served to hold the test specimen (the specimen holder consists of wings of sizes 1.0 m × 1.5 m and 0.5 m × 1.5 m positioned in a right-angled corner configuration, i.e., corresponding in shape and size to the test specimen). A propane gas burner was placed at the bottom of the 90° C. corner of the test specimen to produce heat output of 30 kW. Combustion gases generated during a test were collected by a hood and drawn to an exhaust duct equipped with sensors to measure the temperature, light attenuation, O.sub.2 and CO.sub.2 mole fractions and flow-induced pressure difference in the duct. The performance of the specimen was evaluated for an exposure period of 20 minutes. During the test, the heat release rate was measured by using oxygen consumption calorimetry. The smoke production rate was measured in the exhaust duct based on the attenuation of light. Falling of flaming droplets or particles was visually observed during the first 600 seconds of the heat exposure on the specimen.

Results

[0092] The compositions of the five coating formulations that were tested are tabulated in Table 2 below, together with the results of the SBI test:

TABLE-US-00003 Ex 1 Ex 2 Ex 3 Ex 4 Ex 5 Composition (% by weight) Water-based acrylic resin (Alberdingk 2523 AC; ~ 47-49 % solids) 97.4 51.4 45.2 40.0 45.90 Aqueous suspension of BER (Preparation 1: 37% BER) - 46.0 (17% BER) 46.0 (17% BER) - - Aqueous suspension of BER/MgOH.sub.2 (Preparation 2: 33.0 % BER, 11% Mg(OH).sub.2) - - - 51.2 (17% BER + 5.6% Mg (OH).sub.2) 51.2 (17% BER + 5.6% Mg (OH).sub.2) Water-based Sb2O5 dispersion (NYACOL A1550; 48.0 % APO) - - 6.2 (3% APO) 6.2 (3% APO) - Dispersing and wetting agent (DISPERBYK 2010) 1.0 1.0 1.0 1.0 1.0 Substrate wetting agent (BYK 346) 0.3 0.3 0.3 0.3 0.3 Defoamer (BYK 093) 0.8 0.8 0.8 0.8 0.8 Rheology additive (BYK 420) 0.5 0.5 0.5 0.5 0.3 Dispersing agent (Lopon 800) 0.5 SBI test Fire growth rate index 0.2MJ (FIGRA), [W/s] 0.4MJ 370.74 370.74 377.71 377.71 254.67 254.67 229.7 229.7 189.53 189.53 Total heat release (THR.sub.600s), [MJ] 12.65 15.31 9.75 10.54 8.84 Smoke growth rate index (SMOGRA), [m2/s2] 13.1 26.71 47.40 28.17 21.58 Total smoke production (TSP.sub.600s) [m2] 61.77 71.87 109.31 85.42 78.83

[0093] To better illustrate trends observed in the study, the results of two test variables (Fire Growth Rate Index, FIGRA; and Smoke Growth Rate Index; SMOGRA) are presented graphically in the form of bar diagrams in FIGS. 1 and 2, respectively. In both FIGS. 1 and 2, the bars, from left to right, correspond to Examples 1 to 5, respectively (FR-free coating, BER-added coating, BER/APO-added coating, BER/APO/Mg(OH).sub.2 added-coating and antimony free, BER/Mg(OH).sub.2-added coating, respectively; all are comparative with the exception of Example 5).

[0094] In FIG. 1 is seen that the FIGRA measured for the reference formulation (Example 1) and the BER-added formulation (Example 2) were comparable. As expected, addition of an antimony oxide synergist led to improvement (Example 3), confirming the conventional wisdom that the action of brominated flame retardants leans heavily on the presence of antimony oxide synergist. Addition of another type of flame retardant to the coating - magnesium hydroxide - resulted in a further decrease of FIGRA (Example 4). However, the antimony oxide-free coating of Example 5 - keeping the same levels of BER and magnesium hydroxide as in Example 4 - achieved the best result, i.e., lower FIGRA compared to the BER/APO/Mg(OH).sub.2 - added coating. It is of note that both BER/APO/Mg(OH).sub.2 - added coating and BER/Mg(OH).sub.2-added coating met the requirements of the C classification of the EN 13823 SBI test (FIGRA.sub.0.4.sub.MJ ≤ 250 W/s), but the formulation of the invention demonstrated better performance.

[0095] In FIG. 2 it is seen that addition of flame retardants to a coating/paint applied to a wood, increases the production of smoke during fire. However, lower levels of smoke production were measured for the coating formulation of the invention (Example 5), compared to other flame-retardant coating formulations that were tested.

Example 7

Coating Evaluation: Optical Properties of BER/Mg(OH).SUB.2.-Containing Acrylic Coatings

[0096] To investigate the effect of magnesium hydroxide on the optical properties of the coatings, the formulations of Example 1 (reference; FR-free formulation), Example 2 (comparative; BER-added formulation), and Example 5 (of the invention; BER/Mg (OH).sub.2-added formulation) were applied on a glass surface using an applicator (byko-drive - BYK Gardner GmbH). The tested coating formulation was poured into a rectangular shallow receptable (Film Applicator with 4 Gaps, frame-style by BYK), which moved along the surface; the bottom and top bases of the receptable were open, such that the formulation was spread on the surface when the receptable moved, creating a wet film). After 24 h the dry film was removed from the glass. Haze and transparency were determined using DATACOLOR 650. Results are tabulated below.

TABLE-US-00004 Ex 1 Reference Ex 2 BER Ex 5 BER + MDH Composition (% by weight) Water-based acrylic resin (Alberdingk 2523 AC; ~ 47-49 % solids) 97.4 51.4 45.90 Aqueous suspension of BER (Preparation 1: 37% BER) - 46.0 (17% BER) - Aqueous suspension of BER/MgOH.sub.2 (Preparation 2: 33.0 % BER, 11% Mg(OH).sub.2) - - 51.2 (17% BER + 5.6% Mg(OH).sub.2)) Dispersing and wetting agent (DISPERBYK 2010) 1.0 1.0 1.0 Substrate wetting agent (BYK 346) 0.3 0.3 0.3 Defoamer (BYK 093) 0.8 0.8 0.8 Rheology additive (BYK 420) 0.5 0.5 0.3 Dispersing agent (Lopon 800) 0.5 Optical properties Transparency [%] 92.17 76.54 76.34 Haze [%] 3.3 80.0 78.4 Thickness [micron] 43-45 36-42 42-48

[0097] It is seen that addition of magnesium hydroxide (MDH) to the coating, to aid the brominated flame retardant, does not impair the optical properties of the coating.

Example 8

Cone Calorimeter Test to Evaluate BER/Mg(OH).SUB.2.-Containing Acrylic Coatings on Pine Wood Samples

[0098] The coating formulations of Examples 2, 4 and 5 were applied om pine wood samples and evaluated in a cone calorimeter.

Preparation of the Test Specimen

[0099] 10 mm thick, square shaped pine wood samples (100 mm x 100 mm) were coated by the formulations of Examples 2, 4 and 5. The coatings were applied by a brush - three coats (of the same formulation) were formed; each coat was dried at room temperature for at least four hours before the application of the next coat. Then the samples were dried for at least a week prior to testing.

Test Procedure

[0100] Data was collected by a cone calorimeter [FTT iCone Classic Calorimeter manufactured by Fire Testing Technology, West Sussex, UK] under a heat flux of 50 kW/m.sup.2 over 240 seconds. The specimens were tested without an edged frame sample holder exposing a surface area of 100 cm.sup.2. The FR treated samples were tested in the horizontal orientation 25 mm from the heat source. The samples were wrapped in aluminum foil to prevent edge burning effects.

Results

[0101] The compositions of the coating formulations that were tested are tabulated in Table 4 below, together with the results of the cone calorimeter test.

[0102] Parameters related to the heat release rate (HRR) were given the main consideration. An effective flame-retardant system should show low values of peak and average HRR and a low MARHE (Maximum Average Rate of Heat Emission). HRR curves versus time are shown in FIG. 3.

TABLE-US-00005 Ex 2 BER Ex 4 BER + APO + MDH Ex 5 BER + MDH Composition (% by weight) Water-based acrylic resin (Alberdingk 2523 AC; ~ 47-49 % solids) 51.4 40.0 45.90 Aqueous suspension of BER (Preparation 1: 37% BER) 46.0 (17% BER) - - Aqueous suspension of BER/MgOH.sub.2 (Preparation 2: 33.0 % BER, 11% Mg(OH).sub.2) - 51.2 (17% BER + 5.6% Mg(OH).sub.2) 51.2 (17% BER + 5.6% Mg(OH).sub.2) Water-based Sb2O5 dispersion (NYACOL A1550; 48.0 % APO) - 6.2 (3% APO) - Dispersing and wetting agent (DISPERBYK 2010) 1.0 1.0 1.0 Substrate wetting agent (BYK 346) 0.3 0.3 0.3 Defoamer (BYK 093) 0.8 0.8 0.8 Rheology additive (BYK 420) 0.5 0.5 0.3 Dispersing agent (Lopon 800) 0.5 Cone calorimeter test Peak heat release rate (kW/m.sup.2) 219.2 204.3 192.3 Average heat release rate (kW/m.sup.2) 118.2 115.6 107.2 Maximum average heat release rate (kw/m.sup.2) 126.0 133.3 123.7

[0103] The results obtained for coated pine wood samples by the cone calorimeter test confirm the trend observed in the SBI test for MDF samples (reported in Example 6). That is, the antimony oxide-free coating of Example 5, based on BER/Mg(OH).sub.2, showed the best performance, i.e., better than the coating which was flame retarded by the ternary, antimony oxide containing combination BER/APO/Mg(OH).sub.2.

Example 9

Effect of Dispersants on Long-Term Storage Stability

[0104] The goal of the study was to evaluate the efficiency of different dispersing agents in maintaining the stability of the coating formulations at accelerated storage conditions. Three formulations were made by adding an aqueous suspension consisting of: 31.9 % water; 21 % propylene glycol; 2.6% BYK 2010; 0.5 % BYK 093; 33 % TexFRon® 4002 and 11% Mg(OH).sub.2 (prepared by the Procedure of Preparation 2), to the acrylic resin in the manner described in Example 5, using the same formulation aids, but testing three types of dispersing agents: [0105] Example 9A: nonionic dispersing agent (extra 0.5 % by weight of DISPERBYK 2010, an acrylate copolymer); [0106] Example 9B: anionic dispersing agent; (0.5% by weight of Calgon N, a sodium polyphosphate salt of medium chain length); and [0107] Example 9C: anionic dispersing agent (0.5% by weight of LOPON 800, a sodium polyacrylate salt).

TABLE-US-00006 Ex 9A Ex 9B Ex 9C Composition (% by weight) Water-based acrylic resin (Alberdingk 2523 AC; ~ 47-49 % solids) 45.9 45.9 45.9 Aqueous suspension of BER/MgOH.sub.2 (33 % BER, 11% Mg(OH).sub.2) 51.2 51.2 51.2 Dispersing/wetting agent (DISPERBYK 2010) 1.5 1.0 1.0 Substrate wetting agent BYK 346 0.3 0.3 0.3 Defoamer (BYK 093) 0.8 0.8 0.8 Rheology additive (BYK 420) 0.3 0.3 0.3 Dispersing agent (Calgon N) 0.5 Dispersing agent (Lopon 800) 0.5 Properties Appearance after storage at 40° C. over 4 weeks Non-fluid mass was formed Little separation on surface; after shaking, easily flowable Little separation on surface; after shaking, easily flowable Appearance after storage at 40° C. over 8 weeks Non-fluid mass was formed Little separation on surface; after shaking, easily flowable

[0108] Usually accelerated testing of paints/coating formulations is carried out at elevated temperature for a period of a few weeks and then the formulation is visually examined. The results tabulated in Table 5 indicate that long-term storage stability of the brominated flame retardant/Mg(OH).sub.2 formulation was achieved owing to a combination of a nonionic dispersing agent and an anionic dispersing agent, e.g., one that is based on polyphosphate or polyacrylate, in the form of their sodium salts. In the absence of the anionic surfactant, the formulation transformed into a non-fluid mass (gel or solid). In the presence of an anionic surfactant, little separation was observed at the end of the test (the four and eight weeks of test periods correspond to one and two years of storage under normal conditions, respectively), but the formulation was re-dispersed easily to restore its flowability and functionality.

[0109] As seen in Table 5, a suspension exhibiting especially prolonged stability is achieved with the aid of anionic dispersant based on polyacrylate. This has been further confirmed by ~ one-year test under normal (room temperature) conditions.

Preparation 3 (of the Invention)

Aqueous Dispersion of BER and Al(OH).SUB.3

[0110] An illustrative procedure for preparing 100 g of the BER/Al(OH).sub.3 aqueous dispersion is as follows.

[0111] Water (31.3 g) was added to a mixing vessel, followed by addition of propylene glycol (21.0 g), DISPERBYK 2010 (2.6 g) and BYK 093 (0.5 g) under stirring at a rate of 500 rpm (using R 1303 dissolver stirrer IKA with EUROSTAR power control-visc motor, IKA). Next, alumina trihydrate (11 g of SB-432 from HUBER) was introduced to the vessel under high shear rate at 14000 rpm. After the total amount of the alumina trihydrate was added, TexFRon® 4002 (33 g) was added slowly to the suspension, which was maintained under stirring with the dissolver stirrer until homogeneous suspension was formed. Stirring continued for an additional 30 minutes to afford the final suspension.

Example 10

BER/ Al(OH).SUB.3.-Containing Acrylic Coating Formulation

[0112] An illustrative procedure for preparing 250 g of the BER/Al(OH).sub.3 -containing acrylic coating formulation is as follows.

[0113] Alberdingk 2523 (114.75 g) was added to a 5L plastic jar, followed by the addition of DISPERBYK 2010 (2.5 g), BYK 346 (0.75 g), BYK 093 (2 g) and Lopon 800 (1.25 g) under stirring at a rate of 500 rpm (using R 1303 dissolver stirrer IKA with EUROSTAR power control-visc motor, IKA). After ten minutes, the aqueous suspension of BER/Al(OH).sub.3 of Preparation 3 (128 g) was added. The mixture was maintained under stirring to form a homogeneous formulation. Lastly, BYK 420 (0.75 g) was added. The mixture was maintained under stirring at 500 rpm for 30 min.

Example 11

Cone Calorimeter Test to Evaluate BER/Al(OH).SUB.3.-Containing Acrylic Coatings on Flame Retarded MDF Samples

[0114] The coating formulations of Examples 1, 5 and 10 were applied on MDF samples and evaluated in a cone calorimeter.

Preparation of the Test Specimen

[0115] 18 mm thick, square shaped MDF samples (100 mm × 100 mm) were coated by the formulation of Examples 1, 5 and 10. The coatings were applied by a brush - three coats were formed; [0116] each coat was dried at room temperature for at least four hours before the application of the next coat. Then the samples were dried for at least a week prior to testing.

Test Procedure

[0117] Data was collected by a cone calorimeter [FTT iCone Classic Calorimeter manufactured by Fire Testing Technology, West Sussex, UK]] under a heat flux of 50 kW/m.sup.2 over 240 seconds. The specimens were tested without an edged frame sample holder exposing a surface area of 100 cm.sup.2. The FR treated samples were tested in the horizontal orientation 25 mm from the heat source. The samples were wrapped in aluminum foil to prevent edge burning effects.

Results

[0118] The compositions of the coating formulations that were tested are tabulated in Table 6 below, together with the results of the cone calorimeter test.

TABLE-US-00007 Ex 1 Reference Ex 5 BER + MDH Ex 10 BER + ATH Composition (% by weight) Water-based acrylic resin (Alberdingk 2523 AC; ~ 47-49 % solids) 97.4 45.9 45.9 Aqueous suspension of BER/Mg(OH).sub.2 (Preparation 2: 33.0% BER + 11% Mg(OH).sub.2) - 51.2 (17% BER + 5.6% Mg (OH).sub.2) - Aqueous suspension of BER/Al(OH).sub.2 (Preparation 3: 33.0% BER + 11% Al(OH).sub.3) - - 51.2 (17% BER + 5.6% Al (OH).sub.3) Dispersing, wetting agent(DISPERBYK 2010) 1.0 1.0 1.0 Substrate wetting agent (BYK 346) 0.3 0.3 0.3 Defoamer (BYK 093) 0.8 0.8 0.8 Rheology additive (BYK 420) 0.5 0.5 0.3 Dispersing agent (Lopon 800) 0.5 0.5 Cone calorimeter test Peak heat release rate (kW/m.sup.2) 308.5 247.3 280.6 Average heat release rate (kW/m.sup.2) 118.3 110 113.1 Maximum average rate of heat emission (kw/m.sup.2) 135.3 120.3 124.9

[0119] The results show that coatings based on BER/MDH and BER/ATH show nearly comparable average HRR and MARHE, with an advantage of the former type of coating in relation to the peak HRR.

Example 12 (Reference)

Water-Based Polyurethane Coating Formulation

[0120] For 200 g formulation: Alberdingk PU 9600VP (194.8 g) was added to a mixing vessel, followed by the addition of DISPERBYK 2010 (2 g), BYK 346 (0.6 g) and BYK 093 (1.6 g) under stirring at a rate of 500 rpm (using R 1303 dissolver stirrer IKA with EUROSTAR power control-visc motor, IKA). After ten minutes, BYK 420 (1 g) was added. The mixture was maintained under stirring for 30 minutes.

Example 13 (Comparative)

BER-Containing Polyurethane Coating Formulation

[0121] For 200 g formulation: Alberdingk PU 9600VP (102.8 g) was added to a mixing vessel, followed by the addition of DISPERBYK 2010 (2 g), BYK 346 (0.6 g) and BYK 093 (1.6) under stirring at a rate of 500 rpm (using R 1303 dissolver stirrer IKA with EUROSTAR power control-visc motor, IKA).

[0122] After ten minutes, the aqueous suspension of BER of Preparation 1 (92 g) was added. The mixture was maintained under stirring to form a homogeneous formulation. Lastly, BYK 420 (1 g) was added. The mixture was maintained under stirring for 30 minutes.

Example 14 (Comparative)

BER/APO-Containing Polyurethane Coating Formulation

[0123] For 200 g formulation: Alberdingk PU 9600VP (90.4 g) was added to a mixing vessel, followed by the addition of DISPERBYK 2010 (2 g), BYK 346 (0.6 g) and BYK 093 (1.6 g) under stirring at a rate of 500 rpm (using R 1303 dissolver stirrer IKA with EUROSTAR power control-visc motor, IKA).

[0124] After ten minutes, the aqueous suspension of BER of Preparation 1 (92 g) was added. The mixture was maintained under stirring to form a homogeneous formulation. Next, a water-based dispersion of antimony pentoxide (APO; 12.4 g of 48% by weight aqueous dispersion of nano-sized Sb.sub.2O.sub.5; NYACOL A1550) was introduced to the vessel and stirred for five minutes. Lastly, BYK 420 (1 g) was added. The mixture was stirred for an additional 30 minutes.

Example 15 (of the Invention)

BER/ Mg(OH).SUB.2.-Containing Polyurethane Coating Formulation

[0125] For 200 g formulation: Alberdingk PU 9600VP (91.8 g) was added to a mixing vessel, followed by the addition of DISPERBYK 2010 (2 g), BYK 346 (0.6 g), BYK 093 (1.6 g) and Lopon 800 (1 g) under stirring at a rate of 500 rpm (using R 1303 dissolver stirrer IKA with EUROSTAR power control-visc motor, IKA). After ten minutes, the aqueous suspension of BER/Mg(OH).sub.2 of Preparation 2 (102.4 g) was added. The mixture was maintained under stirring to form a homogeneous formulation. Lastly, BYK 420 (0.6 g) was added. The mixture was maintained under stirring for 30 min.

Example 16

Cone Calorimeter Test to Evaluate BER/Mg(OH).SUB.2.-Containing Polyurethane Coatings on Flame Retarded MDF Samples

[0126] The coating formulations of Examples 12, 13, 14 and 15 were applied on MDF samples and evaluated in a cone calorimeter.

Preparation of the Test Specimen

[0127] 18 mm thick, square shaped MDF samples (100 mm × 100 mm) were coated by the formulation of Examples 12, 13, 14 and 15. The coatings were applied by a brush - three coats (of the same formulation) were formed; each coat was dried at room temperature for at least four hours before the application of the next coat. Then the samples were dried for at least a week prior to testing.

Test Procedure

[0128] Data was collected by a cone calorimeter [FTT iCone Classic Calorimeter manufactured by Fire Testing Technology, West Sussex, UK]] under a heat flux of 50 kW/m.sup.2 over 240 seconds. The specimens were tested without an edged frame sample holder exposing a surface area of 100 cm.sup.2. The FR treated samples were tested in the horizontal orientation 25 mm from the heat source. The samples were wrapped in aluminum foil to prevent edge burning effects.

Results

[0129] The compositions of the coating formulations that were tested are tabulated in Table 7 below, together with the results of the cone calorimeter test. HRR curves versus time are shown in FIG. 4.

TABLE-US-00008 Ex 12 Reference Ex 13 BER Ex 14 BER + APO Ex 15 BER + MDH Composition (% by weight) Water-based polyurethane resin (Alberdingk PU 9600VP; ~ 34-36 % solids) 97.4 51.4 45.2 45.90 Aqueous suspension of BER (Preparation 1: 37% BER) 46.0 (17% BER) 46.0 (17% BER) - Aqueous suspension of BER/MgOH.sub.2 (Preparation 2: 33.0 % BER, 11% Mg(OH).sub.2) - - - 51.2 (17% BER + 5.6% Mg(OH).sub.2) Water-based Sb2O5 dispersion (NYACOL A1550; 48.0 % APO) - - 6.2 (3% APO) - Dispersing and wetting agent (DISPERBYK 2010) 1.0 1.0 1.0 1.0 Substrate wetting agent (BYK 346) 0.3 0.3 0.3 0.3 Defoamer (BYK 093) 0.8 0.8 0.8 0.8 Rheology additive (BYK 420) 0.5 0.5 0.5 0.3 Dispersing agent (Lopon 800) 0.5 Cone calorimeter test Peak heat release rate (kW/m.sup.2) 339 315 252 221 Average heat release rate (kW/m.sup.2) 143 138 130.8 122.6 Maximum average heat release rate (kw/m.sup.2) 150 141.7 125.3 123.7

[0130] The results indicate that polyurethane coatings could benefit from the combination of the invention, BER/Mg(OH).sub.2, which performed very well in retarding the flammability of coated MDF samples, exhibiting lower HRR parameters compared to the conventional BER/antimony oxide combination.

Preparation 4 (Comparative)

Aqueous Dispersion of Brominated Poly[Styrene-Co-Butadiene]

[0131] An illustrative procedure for preparing 400 g of the FR-122P aqueous dispersion is as follows.

[0132] Water (168.9 g) was added to a mixing vessel, followed by addition of propylene glycol (111.8 g), DISPERBYK 2010 (8.4 g), BYK 093 (1.6 g) and Supragil WP (2 g) under stirring at a rate of 400-900 rpm (using R 1303 dissolver stirrer IKA with EUROSTAR power control-visc motor, IKA). Next, FR-122P (106.2 g) was added slowly to the mixture, which was maintained under stirring to form homogeneous suspension. Lastly, BYK 420 (1.2 g) was added slowly. Stirring was continued for additional 30 minutes at 500 ppm.

Preparation 5 (of the Invention)

Aqueous Dispersion of Brominated Poly[Styrene-Co-Butadiene] and Mg(OH).SUB.2

[0133] An illustrative procedure for preparing 400 g of the FR-122P/Mg(OH).sub.2 aqueous dispersion is as follows.

[0134] Water (153.5 g) was added to a mixing vessel, followed by addition of propylene glycol (101.2 g), DISPERBYK 2010 (10.8 g) and BYK 093 (1.6 g) and Supragil WP (2.0 g) under stirring at a rate of 400-900 rpm (using R 1303 dissolver stirrer IKA with EUROSTAR power control-visc motor, IKA). Next, magnesium hydroxide (44 g of FR-20-100-S10 grade from ICL-IP) was introduced to the vessel under high shear rate at 14000 rpm. (high shear disperser was T 25 digital ULTRA-TURRAX instrument, equipped with S 25 KV - 25F dispersing tool, from IKA).

[0135] Lastly, FR-122P (86.9 g) was added slowly to the suspension, which was maintained under stirring (with the dissolver stirrer at 500 rpm) until homogeneous suspension was formed. Stirring continued for additional thirty minutes.

Example 17 (Comparative)

Brominated Poly[Styrene-Co-Butadiene]-Containing Acrylic Coating Formulation

[0136] An illustrative procedure for preparing 200 g of the FR-122P-containing acrylic coating formulation is as follows.

[0137] Alberdingk 2523 (111.1 g) was added to a mixing vessel, followed by the addition of BYK 093 (1.6 g), BYK 346 (0.6 g) and DISPERBYK 2010 (1.4 g), under stirring at a rate of 400 rpm (using R 1303 dissolver stirrer IKA with EUROSTAR power control-visc motor, IKA).

[0138] The rotational speed was increased to 600 rpm and the aqueous suspension of FR-122P of Preparation 4 (84.4 g) was added. The mixture was maintained under stirring to form a homogeneous formulation. Lastly, BYK 420 (1.0 g) was added. The mixture was maintained under stirring for 30 minutes at 500 rpm.

Example 18 (Comparative)

Brominated Poly[Styrene-Co-Butadiene]/APO-Containing Acrylic Coating Formulation

[0139] An illustrative procedure for preparing 200 g of the FR-122P/APO-containing acrylic coating formulation is as follows.

[0140] Alberdingk 2523 (98.7 g) was added to a mixing vessel, followed by the addition of BYK 093 (1.6 g), BYK 346 (0.6 g) and DISPERBYK 2010 (1.4 g) under stirring at a rate of 400 rpm (using R 1303 dissolver stirrer IKA with EUROSTAR power control-visc motor, IKA).

[0141] The rotational speed was increased to 600 rpm and the aqueous suspension of FR-122P of Preparation 4 (84.4 g) was added. The mixture was maintained under stirring to form a homogeneous formulation. Next, a water-based dispersion of antimony pentoxide (APO; 12.4 g of 48% by weight aqueous dispersion of nano-sized Sb.sub.2O.sub.5; NYACOL A1550) was introduced to the vessel under stirring. Lastly, BYK 420 (1.0 g) was added. The mixture was stirred for additional 30 minutes at 500 rpm.

Example 19 (of the Invention)

Brominated Poly[Styrene-Co-Butadiene]/ Mg(OH).SUB.2.-Containing Acrylic Coating Formulation

[0142] An illustrative procedure for preparing 200 g of the FR-122P/Mg(OH).sub.2 containing acrylic coating formulation is as follows.

[0143] Alberdingk 2523 (98.2 g) was added to a mixing vessel, followed by the addition of BYK 093 (1.6 g), BYK 346 (0.6 g), DISPERBYK 2010 (2.0 g) and Lopon 800 (1.0 g) under stirring at a rate of 400 rpm (using R 1303 dissolver stirrer IKA with EUROSTAR power control-visc motor, IKA).

[0144] The rotational speed was increased to 600 rpm and the aqueous suspension of FR-122P/Mg(OH).sub.2 of Preparation 5 (96 g) was added. The mixture was maintained under stirring to form a homogeneous formulation. Lastly, BYK 420 (0.6 g) was added. The mixture was stirred for additional 30 minutes at 500 rpm.

Example 20

Cone Calorimeter Test to Evaluate Brominated Poly[Styrene-Co-Butadiene]/Mg(OH).SUB.2.-Containing Acrylic Coatings on MDF Samples

[0145] The coating formulations of Examples 17, 18 and 19 were applied on MDF samples and evaluated in a cone calorimeter.

Preparation of the Test Specimen

[0146] 18 mm thick, square shaped MDF samples (100 mm × 100 mm) were coated by the formulation of Examples 17, 18 and 19. The coatings were applied by a brush - three coats (of the same formulation) were formed; each coat was dried at room temperature for at least four hours before the application of the next coat. Then the samples were dried for at least a week prior to testing.

Test Procedure

[0147] Data was collected by a cone calorimeter [FTT iCone Classic Calorimeter manufactured by Fire Testing Technology, West Sussex, UK]] under a heat flux of 50 kW/m.sup.2 over 240 seconds. The specimens were tested without an edged frame sample holder exposing a surface area of 100 cm.sup.2. The FR treated plaques were tested in the horizontal orientation 25 mm from the heat source. The samples were wrapped in aluminum foil to prevent edge burning effects.

Results

[0148] The compositions of the coating formulations that were tested are tabulated in Table 8 below, together with the results of the cone calorimeter test. HRR curves versus time are shown in FIG. 5.

TABLE-US-00009 Ex 17 FR-122P Ex 18 FR-122P + APO Ex 19 FR122P + MDH Composition (% by weight) Water-based acrylic resin (Alberdingk 2523 AC; ~ 47-49 % solids) 55.5 49.3 49.1 Aqueous suspension of FR-122P (Preparation 4: 26.6 % FR-122P) 42.2 (11.2% FR-122P) 42.2 (11.2% FR-122P) - Aqueous suspension of FR-122P/Mg (OH).sub.2 (Preparation 5: 21.7% FR-122P + 11% Mg (OH).sub.2) - - 48 (10.4% FR-122P +5.3 % Mg (OH) 2) Water-based Sb2O5 dispersion (NYACOL A1550; 48.0 % APO) 6.2 (3% APO) Dispersing and wetting agent (DISPERBYK 2010) 0.7 0.7 1.0 Substrate wetting agent (BYK 346) 0.3 0.3 0.3 Defoamer (BYK 093) 0.8 0.8 0.8 Rheology additive (BYK 420) 0.5 0.5 0.3 Dispersing agent (Lopon 800) 0.5 Cone calorimeter test Peak heat release rate (kW/m.sup.2) 281.1 256.6 230.3 Average heat release rate (kW/m.sup.2) 114.6 109.3 112.4 Maximum average rate of heat emission (kw/m.sup.2 ) 127.0 174.7 121.0

[0149] The results indicate that in coatings which are flame retarded by brominated poly[styrene-co-butadiene], Mg(OH).sub.2 could serve as a replacement for antimony oxide, generating antimony oxide-free coatings which show acceptable burning properties.

Preparation 6 (Comparative)

Aqueous Dispersion of Brominated Polystyrene

[0150] Water (126.7 g) was added to a mixing vessel, followed by addition of propylene glycol (83.8 g), DISPERBYK 2010 (6.3 g), BYK 093 (1.2 g) and Supragil WP (1.5 g) under stirring at a rate of 500 rpm (using R 1303 dissolver stirrer IKA with EUROSTAR power control-visc motor, IKA). Next, FR-803P (79.7 g) was added slowly to the mixture, which was maintained under stirring to form homogeneous suspension. Lastly, BYK 420 (0.9 g) was added slowly. Stirring was continued for additional 30 minutes at 500 ppm, to give 300 g of an aqueous dispersion of brominated polystyrene.

Preparation 7 (of the Invention)

Aqueous Dispersion of Brominated Polystyrene and Mg(OH).SUB.2

[0151] Water (114.5 g) was added to a mixing vessel, followed by addition of propylene glycol (75.9 g), DISPERBYK 2010 (8.1 g) and BYK 093 (1.2 g) and Supragil WP (1.5 g) under stirring at a rate of 500 rpm (using R 1303 dissolver stirrer IKA with EUROSTAR power control-visc motor, IKA). Next, magnesium hydroxide (33 g of FR-20-100-S10 grade from ICL-IP) was introduced to the vessel under high shear rate at 14000 rpm. (high shear disperser was T 25 digital ULTRA-TURRAX instrument, equipped with S 25 KV - 25F dispersing tool, from IKA).

[0152] FR-803P (65.2 g) was added slowly to the suspension, which was maintained under stirring (with the dissolver stirrer at 500 rpm) until homogeneous suspension was formed. Lastly, BYK 420 (0.6 g) was added. Stirring continued for additional thirty minutes, to give 300 g of the formulation.

Example 21 (Comparative)

Brominated Polystyrene-Containing Acrylic Coating Formulation

[0153] An illustrative procedure for preparing 200 g of the FR-803P containing acrylic coating formulation is as follows.

[0154] Alberdingk 2523 (111.1 g) was added to a mixing vessel, followed by the addition of BYK 093 (1.6 g), BYK 346 (0.6 g) and DISPERBYK 2010 (1.4 g) under stirring at a rate of 500 rpm (using R 1303 dissolver stirrer IKA with EUROSTAR power control-visc motor, IKA).

[0155] The rotational speed was increased to 600 rpm and the aqueous suspension of FR-803P of Preparation 6 (84.4 g) was added. The mixture was maintained under stirring to form a homogeneous formulation. Then BYK 420 (1 g) was added. The mixture was maintained under stirring for 30 minutes at 500 rpm.

Example 22 (Comparative)

Brominated Polystyrene/APO/Mg(OH).SUB.2.-Containing Acrylic Coating Formulation

[0156] An illustrative procedure for preparing 200 g of the FR-803P/APO-containing acrylic coating formulation is as follows.

[0157] Alberdingk 2523 (85.8 g) was added to a mixing vessel, followed by the addition of BYK 093 (1.6 g), BYK 346 (0.6 g), DISPERBYK 2010 (2.0 g) and Lopon 800 (1.0 g) under stirring at a rate of 500 rpm (using R 1303 dissolver stirrer IKA with EUROSTAR power control-visc motor, IKA).

[0158] The rotational speed was increased to 600 rpm and the aqueous suspension of FR-803P/Mg(OH).sub.2 of Preparation 7 (96 g) was added. The mixture was maintained under stirring to form a homogeneous formulation. Next, a water-based dispersion of antimony pentoxide (APO; 12.4 g of 48% by weight aqueous dispersion of nano-sized Sb.sub.2O.sub.5; NYACOL A1550) was introduced to the vessel under stirring. Lastly, BYK 420 (0.6 g) was added. The mixture was stirred for additional 30 minutes at 500 rpm.

Example 23 (of the Invention)

Brominated Polystyrene/Mg(OH).SUB.2.-Containing Acrylic Coating Formulation

[0159] An illustrative procedure for preparing 200 g of the FR-803P/Mg(OH).sub.2 containing acrylic coating formulation is as follows.

[0160] Alberdingk 2523 (98.2 g) was added to a mixing vessel, followed by the addition of BYK 093 (1.6 g), BYK 346 (0.6 g), DISPERBYK 2010 (2.0 g) and Lopon 800 (1.0 g) under stirring at a rate of 500 rpm (using R 1303 dissolver stirrer IKA with EUROSTAR power control-visc motor, IKA).

[0161] The rotational speed was increased to 600 rpm and the aqueous suspension of FR-803P/Mg(OH).sub.2 of Preparation 7 (96 g) was added. The mixture was maintained under stirring to form a homogeneous formulation. Lastly, BYK 420 (0.6 g) was added. The mixture was stirred for additional 30 minutes at 500 rpm.

Example 24

Cone Calorimeter Test to Evaluate Brominated Polystyrene/Mg(OH).SUB.2.-Containing Acrylic Coatings on Flame Retarded MDF Wood Samples

[0162] The coating formulations of Examples 21, 22 and 23 were applied om MDF wood samples and evaluated in a cone calorimeter.

Preparation of the Test Specimen

[0163] 18 mm thick, square shaped MDF samples (100 mm x 100 mm) were coated by the formulation of Examples 21, 22 and 23. The coatings were applied by a brush - three coats were formed; each coat was dried at room temperature for at least four hours before the application of the next coat. Then the samples were dried for at least a week prior to testing.

Test Procedure

[0164] Data was collected by a cone calorimeter [FTT iCone Classic Calorimeter manufactured by Fire Testing Technology, West Sussex, UK] under a heat flux of 50 kW/m.sup.2 over 240 seconds. The specimens were tested without an edged frame sample holder exposing a surface area of 100 cm.sup.2. The FR treated samples were tested in the horizontal orientation 25 mm from the heat source. The samples were wrapped in aluminum foil to prevent edge burning effects.

Results

[0165] The compositions of the coating formulations that were tested are tabulated in Table 9 below, together with the results of the cone calorimeter test.

TABLE-US-00010 Ex 21 FR-803P Ex 22 FR-803P + APO + MDH Ex 23 FR-803P + MDH Composition (% by weight) Water-based acrylic resin (Alberdingk 2523 AC; ~ 47-49 % solids) 55.6 42.9 49.1 Aqueous suspension of FR-803P (Preparation 6: 26% FR-803P) 42.2 (11 % FR-803P) - - Aqueous suspension of FR-803P/MgOH.sub.2 (Preparation 7: 21.7% FR-803P, 11% Mg(OH).sub.2) - 48.0 (10.4% FR-803P + 5.3% Mg (OH).sub.2) 48.0 (10.4% FR-803P + 5.3% Mg (OH).sub.2) Water-based Sb2O5 dispersion (NYACOL A1550; 48.0 % APO) - 6.2 (3% APO) - Dispersing and wetting agent (DISPERBYK 2010) 0.7 1.0 1.0 Substrate wetting agent (BYK 346) 0.3 0.3 0.3 Defoamer (BYK 093) 0.8 0.8 0.8 Rheology additive (BYK 420) 0.5 0.3 0.3 Dispersing agent (Lopon 800) 0.5 0.5 Cone calorimeter test Peak heat release rate (kW/m.sup.2) 323.2 257.7 266.6 Average heat release rate (kW/m.sup.2) 122.0 123.2 119.4 Maximum average heat release rate (kw/m.sup.2) 140.2 131.6 127.7

[0166] The results indicate that the antimony oxide-free coating of Example 23, based on brominated polystyrene/Mg(OH).sub.2, was comparable to the coating which was flame retarded by the ternary, antimony oxide containing combination consisting of brominated polystyrene/APO/Mg(OH).sub.2 (Example 22).

Preparation 8 (Comparative)

Aqueous Dispersion of FR-245

[0167] Water (168.8 g) was added to a mixing vessel, followed by addition of propylene glycol (111.8 g), DISPERBYK 2010 (8.4 g), BYK 093 (1.6 g) and Supragil WP (2.0 g) under stirring at a rate of 500 rpm (using R 1303 dissolver stirrer IKA with EUROSTAR power control-visc motor, IKA). Next, FR-245 (106.3 g) was added slowly to the mixture, which was maintained under stirring to form homogeneous suspension. Lastly, BYK 420 (1.2 g) was added slowly. Stirring was continued for additional 30 minutes at 500 ppm, to give 400 g of an aqueous dispersion of FR-245.

Preparation 9 (of the Invention)

Aqueous Dispersion of FR-245 and Mg(OH).SUB.2

[0168] Water (152.7 g) was added to a mixing vessel, followed by addition of propylene glycol (101.2 g), DISPERBYK 2010 (10.8 g) and BYK 093 (1.6 g) and Supragil WP (2.0 g) under stirring at a rate of 500 rpm (using R 1303 dissolver stirrer IKA with EUROSTAR power control-visc motor, IKA). Next, magnesium hydroxide (44 g of FR-20-100-S10 grade from ICL-IP) was introduced to the vessel under high shear rate at 14000 rpm. (high shear disperser was T 25 digital ULTRA-TURRAX instrument, equipped with S 25 KV - 25F dispersing tool, from IKA) .

[0169] FR-245 (86.9 g) was added slowly to the suspension, which was maintained under stirring (with the dissolver stirrer at 500 rpm) until homogeneous suspension was formed. Then BYK 420 (1.2 g) was added. Stirring continued for additional thirty minutes, to give 400 g of an aqueous dispersion of FR-245/Mg (OH).sub.2.

Example 25 (Comparative)

FRContaining Acrylic Coating Formulation

[0170] An illustrative procedure for preparing 200 g of the FR-245 containing acrylic coating formulation is as follows.

[0171] Alberdingk 2523 (111.1 g) was added to a mixing vessel, followed by the addition of BYK 093 (1.6 g), BYK 346 (0.6 g) and DISPERBYK 2010 (1.4 g) under stirring at a rate of 500 rpm (using R 1303 dissolver stirrer IKA with EUROSTAR power control-visc motor, IKA).

[0172] The rotational speed was increased to 600 rpm and the aqueous suspension of FR-245 of Preparation 8 (84.4 g) was added. The mixture was maintained under stirring to form a homogeneous formulation. Lastly, BYK 420 (1.0 g) was added. The mixture was maintained under stirring for 30 minutes at 500 rpm.

Example 26 (Comparative)

FR-245/APO-Containing Acrylic Coating Formulation

[0173] An illustrative procedure for preparing 200 g of the FR-245/APO-containing acrylic coating formulation is as follows.

[0174] Alberdingk 2523 (98.72 g) was added to a mixing vessel, followed by the addition of BYK 093 (1.6 g), BYK 346 (0.6 g), DISPERBYK 2010 (1.4 g) under stirring at a rate of 500 rpm (using R 1303 dissolver stirrer IKA with EUROSTAR power control-visc motor, IKA).

[0175] The rotational speed was increased to 600 rpm and the aqueous suspension of FR-245 of Preparation 8 (84.4 g) was added. The mixture was maintained under stirring to form a homogeneous formulation. Next, a water-based dispersion of antimony pentoxide (APO; 12.4 g of 48% by weight aqueous dispersion of nano-sized Sb.sub.2O.sub.5; NYACOL A1550) was introduced to the vessel under stirring. Lastly, BYK 420 (1.0 g) was added. The mixture was stirred for additional 30 minutes at 500 rpm.

Example 27 (of the Invention)

FR-245/Mg(OH).SUB.2.-Containing Acrylic Coating Formulation

[0176] An illustrative procedure for preparing 200 g of the FR-245/Mg(OH).sub.2 containing acrylic coating formulation is as follows.

[0177] Alberdingk 2523 (98.2 g) was added to a mixing vessel, followed by the addition of BYK 093 (1.6 g), BYK 346 (0.6 g), DISPERBYK 2010 (2.0 g) and Lopon 800 (1.0 g) under stirring at a rate of 500 rpm (using R 1303 dissolver stirrer IKA with EUROSTAR power control-visc motor, IKA).

[0178] The rotational speed was increased to 600 rpm and the aqueous suspension of FR-245/Mg(OH).sub.2 of Preparation 9 (96 g) was added. The mixture was maintained under stirring to form a homogeneous formulation. Lastly, BYK 420 (0.6 g) was added. The mixture was stirred for additional 30 minutes at 500 rpm.

Example 28

Cone Calorimeter Test to Evaluate FR-245/Mg(OH).SUB.2.-Containing Acrylic Coatings on Flame Retarded MDF Wood Samples

[0179] The coating formulations of Examples 25, 26 and 27 were applied om MDF wood samples and evaluated in a cone calorimeter.

Preparation of the Test Specimen

[0180] 18 mm thick, square shaped MDF samples (100 mm × 100 mm) were coated by the formulation of Examples 25, 26 and 27. The coatings were applied by a brush - three coats (of the same formulation) were formed; each coat was dried at room temperature for at least four hours before the application of the next coat. Then the samples were dried for at least a week prior to testing.

Test Procedure

[0181] Data was collected by a cone calorimeter [FTT iCone Classic Calorimeter manufactured by Fire Testing Technology, West Sussex, UK] under a heat flux of 50 kW/m.sup.2 over 240 seconds. The specimens were tested without an edged frame sample holder exposing a surface area of 100 cm.sup.2. The FR treated samples were tested in the horizontal orientation 25 mm from the heat source. The samples were wrapped in aluminum foil to prevent edge burning effects.

Results

[0182] The compositions of the coating formulations that were tested are tabulated in Table 10 below, together with the results of the cone calorimeter test.

TABLE-US-00011 Ex 25 FR-245 Ex 26 FR-245 + APO Ex 27 FR-245 + MDH Composition (% by weight) Water-based acrylic resin (Alberdingk 2523 AC; ~ 47-49 % solids) 55.6 49.36 49.1 Aqueous suspension of FR-245 (Preparation 8: 26.5% FR-245) 42.2 (11 % FR-245) 42.2 (11 % FR-245) - Aqueous suspension of FR-245/MgOH.sub.2 (Preparation 9: 21.7% FR-245, 11% Mg(OH).sub.2) - - 48.0 (10.4% FR-245 + 5.3% Mg(OH).sub.2) Water-based Sb2O5 dispersion (NYACOL A1550; 48.0 % APO) - 6.2 (3% APO) - Dispersing and wetting agent (DISPERBYK 2010) 0.7 0.7 1.0 Substrate wetting agent (BYK 346) 0.3 0.3 0.3 Defoamer (BYK 093) 0.8 0.8 0.8 Rheology additive (BYK 420) 0.5 0.5 0.3 Dispersing agent (Lopon 800) 0.5 Cone calorimeter test Peak heat release rate (kW/m.sup.2) 349.6 359.0 276.5 Average heat release rate (kW/m.sup.2) 126.8 120.0 122.4 Maximum average heat release rate (kw/m.sup.2) 140.0 139.8 135.4

[0183] The results indicate that magnesium hydroxide can replace antimony oxide in FR-245 based coatings, to provide coatings showing comparable, and perhaps even reduced, flammability.

Example 29 (Comparative)

Cone Calorimeter Test to Evaluate DPDPE/Mg(OH).SUB.2.-Containing Acrylic Coatings on MDF Samples

[0184] The goal of the study was to examine the efficiency of Mg(OH).sub.2 as a replacement for APO in acrylic coatings which are flame retarded by a brominated compound, i.e., nonpolymeric flame retardant. The brominated compound chosen for the study was decabromodiphenyl ethane (DPDPE), a strong flame retardant with an exceptionally high (~80%) bromine content:

##STR00010##

[0185] Aqueous suspensions of DPDPE and DPDPE/Mg(OH).sub.2 were prepared using the procedures set out in Preparations 4 and 5. The compositions (% by weight) are set out below.

TABLE-US-00012 Preparation 10 DPDPE in water Preparation 11 DPDPE/Mg(OH).sub.2 in water Water 42.21 38.37 Propylene glycol 27.94 25.3 Dispersing and wetting agent (DISPERBYK 2010) 2.09 2.7 Defoamer (BYK 093) 0.4 0.4 Anionic surfactant (Supragil WP) 0.5 0.5 DPDPE (FR 1410) 26.56 21.73 Rheology additive (BYK 420) 0.3 - Mg(OH).sub.2 - 11

[0186] Next, coating formulations were prepared and tested in cone calorimeter (see preparation procedures described in Examples 17-19, and test protocol in Example 20).

[0187] The compositions of the coating formulations that were tested are tabulated in Table 12 below, together with the results of the cone calorimeter test.

TABLE-US-00013 Ex 29A DPDPE Ex 29B DPDPE + APO Ex 29C DPDPE + MDH Composition (% by weight) Water-based acrylic resin (Alberdingk 2523 AC; ~ 47-49 % solids) 55.56 49.36 49.1 Aqueous suspension of DPDPE (Preparation 10: 26.6 % FR-1410) 42.2 (11.2% DPDPE) 42.2 (11.2% DPDPE) - Aqueous suspension of DPDPE/Mg(OH).sub.2 (Preparation 11: 21.7% FR-1410 + 11% Mg (OH).sub.2) - - 48 (10.4% DPDPE +5.3 % Mg (OH) 2) Water-based Sb2O5 dispersion (NYACOL A1550; 48.0 % APO) 6.2 (3% APO) Dispersing and wetting agent (DISPERBYK 2010) 0.7 0.7 1.0 Substrate wetting agent (BYK 346) 0.3 0.3 0.3 Defoamer (BYK 093) 0.8 0.8 0.8 Rheology additive (BYK 420) 0.5 0.5 0.3 Dispersing agent (Lopon 800) 0.5 Cone calorimeter test Peak heat release rate (kW/m.sup.2) 290 260 273 Average heat release rate (kW/m.sup.2) 105.8 99.2 100.5 Maximum average rate of heat emission (kw/m.sup.2 ) 125.9 119.4 121.7

[0188] APO and Mg(OH).sub.2 both improve the action of DPDPE in the coating formulations, reducing HRR parameters. However, the combination of DPDPE/APO was shown to be slightly more efficient than DPDPE/Mg(OH).sub.2.