Brominated epoxy polymers as wood coating flame retardant formulations

Abstract

The present invention discloses novel flame retardant aqueous formulations comprising micronized particles of brominated epoxy polymers having a predetermined molecular weight, their use as flame retardant coating of wood-based substrates, their preparation and flame-retarded wood-based substrates prepared by using them.

Claims

1. A flame retarded wood-based substrate having a homogeneous flame retardant film thereon, said film comprising micronized particles of brominated epoxy polymer according to Formula I, ##STR00002## wherein n indicates the degree of polymerization having a molecular weight ranging from 1,000 to 5,000 grams/mol; attached to the surface of said wood-based substrate, wherein: said micronized particles have a size distribution of d50<5 micron, d90<10 micron and d99<30 micron; said homogenous flame retardant film comprises a binding agent in an amount of at least 35% by weight; and said homogenous flame retardant film optionally further comprises at least one additive selected from the group consisting of a flame retardant synergist, a smoldering suppressant agent, a surface active agent, an antifoaming agent, a preservative, a stabilizing agent, a thickening agent, a dispersing agent, a wetting agent, a suspending agent, a pH buffer, a hardener, a curing agent, a sequestering agent, a detergent, a dye, a pigment and any mixture thereof.

2. The flame retarded wood-based substrate of claim 1, wherein said film is transparent.

3. The flame retarded wood-based substrate of claim 1, wherein said wood-based substrate displays its original color.

4. The flame retarded wood-based substrate of claim 1, having an “after flame” time ranging from 0 seconds to 10 seconds.

5. The flame retarded wood-based substrate of claim 1, wherein said flammable wood-based substrate is a natural wood substrate or an engineered wood and any combination thereof.

Description

FIGURES

(1) The following figures depict the results of flammability tests carried out in a cone calorimeter as described in Example 4.

(2) FIG. 1: depicts the heat emission of samples 1 to 6.

(3) FIG. 2: depicts the smoke emission of samples 1 to 6.

(4) FIG. 3: presents calculated calorimetric parameters of samples 1 to 6.

EXAMPLES

(5) Materials and Methods

(6) Brominated Flame Retardant Polymer

(7) TexFRon®4002 (2,2′-[(1-Methylethylidene)bis[(2,6-dibromo-4, l-phenylene)-oxymethylene]]-bisoxirane polymer with 2,2′,6,6′-tetrabromo-4,4′-isopropylidenediphenol and 2,4,6-tribromophenol. CAS #135229-48-0).

(8) FR1410 used for comparative Example 6 Decabromodiphenyl ethane, CAS 84852-53-9.

(9) Resins

(10) Acrylic based resins: Alberdingk® AC 2523 (47-49% solids, Minimum Film Formation Temperature (MFFT) 0° C.), Alberdingk® AC 2019 (45-47% solids, MFFT 17° C.), Primal™ IW-3311 (41% solids. MFFT 42° C.), polyurethane based resin: Alberdingk® U9600 VP (34-36% solids, MFFT 0° C.);

(11) Auxiliary Additives

(12) BYK-093: defoamer reagent, contains a mixture of foam-destroying polysiloxanes and hydrophobic solids in polyglycol, was obtained from BYK-Chemie GmbH.

(13) BYK-346: wetting agent, a solution of a polyether-modified polysiloxane was obtained from BYK-Chemie GmbH.

(14) BYK-420: thickening agent and anti-settling agent, a solution of a modified urea obtained from BYK-Chemie GmbH.

(15) BYK-2010: wetting and dispersing agent, structured acrylate copolymer with pigment affinic groups obtained from BYK-Chemie GmbH.

(16) Tafigel® PUR 45: thickening agent, non-ionic polyurethane in butyl triglycol/water was obtained from Munzing Chemie GmbH.

(17) PG—propylene glycol coalescing agent obtained from Gadot Chemicals.

(18) Rheolate® 212: thickening agent promoting improved flow of water-based systems, polyether polyurethane based resin in water was obtained from Elementis specialties.

(19) Antimony pentoxide (APO)—flame retardant synergist was obtained from Nyacol Nano Technologies, Inc.

(20) Flammability Tests:

(21) The cone calorimeter and the NFPA 701 vertical burn tests were used for quantitative flammability analysis of the formulations set forth above. Cone calorimeter analysis was conducted in order to evaluate the flammability of the compositions prepared. Data was collected by the cone calorimeter under a heat flux of 50 kW/m.sup.2, and specimen separation of 25 mm. The parameters which were investigated were the ignition time, heat release rate (HRR), total heat release (THR) and the HRR peak.

(22) NFPA 701: a method for assessing the propagation of flame in various textiles and films under specified fire test conditions. In this test, a hanging substrate under testing, (plywood was used) was exposed to a 10 cm flame for 45 seconds. After said 45 seconds, the flame was automatically put out, while the flame which was caught by the tested substrate was monitored until it was auto-extinguished, and the duration of said auto-extinguishing was reported in seconds. In the measurements carried out for the present invention, a sample that did not demonstrate auto-extinguishing properties (burned completely) under the test conditions as described above, was reported as “fail”.

(23) Cone calorimetry: a fire testing tool based on the principle that the amount of heat released from a burning sample is directly related to the amount of oxygen consumed during the combustion. Briefly, in the cone calorimeter, a radiant heat is projected onto a sample before ignition and during burning of the sample, and several parameters, such as time to ignition and the heat release profile of the tested sample are measured. The amount of heat a material generates is directly correlated with the severity of a fire, such as fire growth rate. The cone gathers data regarding the ignition time, mass loss, combustion products, heat release rate and other parameters associated with its burning properties.

Example 1—Preparation of Micronized Particles

(24) Preparation of micronized end-capped brominated epoxy TexFRon® 4002 (2,2′-[(1-Methylethylidene)bis[(2,6-dibromo-4,1-phenylene)oxymethylene]]bisoxirane polymer with 2,2′,6,6′-tetrabromo-4,4′-isopropylidenediphenol and 2,4,6-tribromophenol, CAS #135229-48-0). TexFRon® 4002 was micronized by a Micronizer Jet Mill (dry milling). The particle size distribution before and after the milling was measured using Malvern Mastersizer 2000 in water (3 minutes ultrasonic treatment, 500 psi, 1250 rpm).

Example 2—Preparation of TexFRon® 4002 Aqueous Dispersions—Premix 4002

(25) TexFRon 4002 (66 grams) having a size distribution of d.sub.50<5 microns, d.sub.90<10 microns, d.sub.99<30 microns, was added to a mixed solution containing deionized water (84.8 grams), Disperbyk-2010 (5 grams), BYK-093 (1 g) and propylene glycol (42 g) using a dissolver stirrer (R 1303 Dissolver stirrer IKA with EUROSTAR power control-visc motor, IKA) at a rate of 600 RPM. The dispersion was allowed to mix for 10 minutes. Following said mixing, BYK 420 (1.2 g) was added slowly to the mixture and was left to stir for another 30 minutes, producing 200 gr TexFRon 4002 remix. Table 1 describes the premix composition in terms of percent by weight:

(26) TABLE-US-00001 TABLE 1 Ingredient wt % Water 42.4 PG 21 BYK-2010 2.5 BYK-093 0.5 Flame retardant (TexFRon 4002) 33 BYK-420 0.6

(27) The viscosity of TexFRon 4002 premix was measured in Brookfield DVII viscometer, equipped with spindle S63, and gave rise to the following values: 2499 cp at 0.3 rpm, 177 cp at 60 rpm, and 158 cp at 100 rpm; this pseudoplastic behavior is highly desirable for paint applications.

Example 3

(28) A. The preparation of different wood coating formulations comprising TexFRon® 4002 was carried out in two consecutive steps, including the preparation of the water dispersion TexFRon 4002 premix following the procedure described above in Example 2, and mixing said premix with the following ingredients as follows:

(29) For the preparation of formulation comprising 15 wt % TexFRon 4002, Alberdingk 2523 AC (102.4 g), BYK 093 (1.6 g), BYK 346 (0.6 g) and DisperBYK-2010 (2 g) were added during stirring in a dissolver stirrer (R 1303 Dissolver stirrer IKA with EUROSTAR power control-vise motor, IKA) at a rate of 400 RPM. After 10 minutes of mixing, TexFRon 4002 premix (92.4 g) was added during stirring with increased stirring rate of 600 rpm, followed by the addition of Rheolate-212 to form 200 gr of stable acrylic fire retardant coating.

(30) For formulations comprising Antimony Pentoxide dispersion, the latter was slowly added after Rheolate-212 in the last stage followed by additional 10 minutes stirring.

(31) Several coating formulations were prepared as detailed in Table 2, utilizing the preparation procedure as described above, and varying in TexFRon 4002 premix and resin (Alberdingk AC-2523) content as described in Table 2 herein below in terms of percent by weight.

(32) B. Sample preparation: the formulations obtained as described in step A were applied onto plywood boards (30*15*0.3 cm) and pine wood samples (10*10*1 cm) utilizing paint brush (3 layers, with intervals of at least 4 hours to allow drying) on both sides of the board at room temperature. The resultant coatings appeared to have a mat finishing and the original color of the wood samples was observed. The plywood samples were used for the NFPA testing and the pine samples were used for the cone calorimeter testing.

(33) The solids fraction (% solids) in the formulations which appeared in Table 2 was measured by Loss On Drying (LOD) HR-Halogen (Mettler Toledo). The sample was applied on aluminum plate and was heated to 120′C. The weight loss was measured after getting stable weight, the solid fraction was calculated according to the following: 100%−LOD=% solids in formulation

(34) The coated plywood substrates were examined under NFPA 701 testing conditions as described above and the auto-extinguishing time was recorded per each coating formulation as summarized in Table 2:

(35) TABLE-US-00002 TABLE 2 Sample number 1 2 3 4 5 6 Sample name 15 wt % 15 wt % 10 wt % 10 wt % 5 wt % 2.5 wt % TexFRon TexFRon TexFRon TexFRon TexFRon TexFRon 4200 4200 + APO 4200 4200 + APO 4200 + APO 4200 + APO Alberdingk 51.2 39.59 67.4 59.86 78.63 88.02 AC 2523 (wt %) APO (wt %) — 11.61 — 7.54 3.77 1.88 BYK-093 (wt %) 0.8 0.8 0.8 0.8 0.8 0.8 BYK-346 (wt %) 0.3 0.3 0.3 0.3 0.3 0.3 BYK-2010 (wt %) 1 1 1 1 1 1 Premix-4002 (wt %) 46.2 46.2 30 30 15 7.5 Rheolate-212 (wt %) 0.5 0.5 0.5 0.5 0.5 0.5 NFPA 701 (sec) 9.03 3.23 55.4 2.27 fail fail % solids (measured) 40.8 40.7 46.5 43.5 44.4 47.1

(36) According to Table 2, it can be seen that samples comprising less than 10 wt % TexFRon 4002 in their coating formulation failed in the burning test—and were totally burned. Additionally, sample number 3, having 10 wt % TexFRon 4002 which was APO-free, took a long time to auto-extinguish (55.4 seconds) while a similar sample having 10 wt % TexFRon 4002 and containing APO demonstrated a much shorter auto-extinguishing time (2.27 seconds). This later effect of APO presence was consistent also in the samples comprising 15 wt % TexFRon 4002 (samples 1 and 2), where APO appeared to shorten the time needed in order to achieve an auto-extinguished sample.

Example 4

(37) Flammability measurements according to ASTM E1354 standard were carried out utilizing cone calorimeter Stanton Redcroft. The heat release of coated 100 mm×100 mm×10 mm plywood samples were measured, using heat flux of 50 kW/m.sup.2 and Specimen Separation of 25 mm.

(38) Calculated values: 1) Smoke parameter: Peak heat release*SEA*10.sup.−3 (SEA is specific extinction area m.sup.2 kg.sup.−1). 2) Fire performance index: Time of ignition/peak heat release rate

(39) Heat emission measurement of the samples prepared according to Table 2 are depicted in FIG. 1. According to FIG. 1, APO containing samples 2 and 4 having 15 and 10 wt % TexFRon 4002, respectively, demonstrated a lower peak heat release rate than corresponding samples 3 and 5, which were APO-free. According to FIG. 2, similar samples in terms of brominated epoxy flame retardant content demonstrated similar smoke release values with and without APO. According to FIG. 3, the overall fire performance index demonstrated a higher flame performance index for APO-containing samples 2 and 4, having 15 and 10 wt % TexFRon 4002, respectively, in comparison to corresponding samples 3 and 5, which were APO-free. Additionally, it was noted that an increase in the flame retardant content within the sample appears to result mostly in an increase in the fire performance index.

Example 5

(40) APO-free wood coating formulations comprising 15% TexFRon 4200 and varying resins were prepared as described in Example 3, by replacing Alberdingk AC-2523 with the desired resin in each formulation as indicated in Table 3 herein below. The obtained formulations were applied onto plywood boards as described hereinabove. The different APO-free coating formulations and their corresponding NFPA testing results are summarized in Table 3:

(41) TABLE-US-00003 TABLE 3 DOW Alberdingk Alberdingk Alberdingk Primal AC 2523 AC 2019 U9600 VP IW-3311 Resin (wt %) 51.2 51.2 53.2 53.2 BYK-093 0.8 0.8 — — (wt %) BYK-346 0.3 0.3  0.3  0.3 (wt %) BYK-2010 1 1 — — (wt %) Premix-4002 46.2 46.2 46.2 46.2 (wt %) Rheolate-212 0.5 0.5 — — (wt %) Tafigel PUR 45 — —  0.3  0.3 (wt %) NFPA 701 (sec) 9.03 33.4 22.8  9.55 % solids 40 39 34   37   (calculated)

(42) According to Table 3, Alberdingk AC-2523 acrylic resin yielded the best results in terms of shortest time to achieve an auto-extinguished sample.

Example 6

(43) A comparative example between the wood coating formulations of the invention which are based on TexFRon 4002 flame retardant and wood coating formulations based on the known flame retardant FR-1410 (reference samples) was carried out in the following manner: two coating formulations having 15 wt % flame retardant material and two coating formulations having 10 wt % flame retardant material where prepared for each flame retardant (TexFRon 4002 and FR-1410) as described in Example 3. One of each coating formulation was APO-free and the other had APO additive therein according to Table 4:

(44) TABLE-US-00004 TABLE 4 15% TexFRon 15% TexFRon 15% FR- 15% FR- 10% TexFRon 10% TexFRon 10% FR- 10% FR- 4200 4200 + APO 1410 1410 + APO 4200 4200 + APO 1410 1410 + APO Alberdingk 51.2 39.59 51.5 34.2 67.4 59.86 67.4 56.4 AC 2523 (wt %) APO (wt %) — 11.61 — 17 — 7.54 — 11 BYK-093 (wt %) 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 BYK-346 (wt %) 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 BYK-2010 (wt %) 1 1 1 1 1 1 1 1 ***FR Premix 46.2 46.2 45.9 46.2 30 30 30 30 (wt %) Rheolate-212 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 (wt %) NFPA 701 (sec) 9.03 3.23 8.91 3.95 55.4 2.27 fail 2.7 ***The premix composition used for FR-1410 was prepared according to the procedure described in Example 2, only utilizing FR-1410 instead of TexFRon 4002 as the main flame retardant. ***The premix composition used for FR-1410 was prepared according to the procedure described in Example 2, only utilizing FR-1410 instead of TexFRon 4002 as the main flame retardant.

(45) The wood boards coated with formulations based on FR-1410 appeared white in comparison to the wood boards coated with TexFRon 4002 based formulations, which appeared to maintain the original wood color as a result of the transparent coating which was formed.

(46) According to Table 4 it can be seen that for both flame retardants (FR-1410 and TexFRon 4002) the presence of APO within the coating improved the auto-extinguishing time of the samples. Additionally, it was demonstrated, that in the presence of APO, TexFRon 4002 formulations were shown to be superior to FR-1410 formulations in terms of auto-extinguishing time of the corresponding samples. An additional parameter that was demonstrated is the wood appearance after the coating. The wooden sample coated with FR-1410 appeared to be white in comparison to the wooden sample coated with TexFRon 4002. This advantage of the flame retardant coating of the invention is achieved even though the particle size distribution of the FR-1410 is similar to the particle size distribution of TexFRon 4002. It should be noted that the solid wt % was similar for both FR-1410 and TexFRon 4002 formulations.

Example 7

(47) Paint formulation was applied on glass using an applicator (byko-drive by BYK) with 10 cm Film Casting Knife (BYK) forming a 300 micron wet film. After 24 h the dry film was pulled-off from the glass and was analyzed for transparency using DATACOLOR 650 (by DATACOLOR). The transparency properties of the flame retardant coating of the invention are detailed in Table 5:

(48) TABLE-US-00005 TABLE 5 Sample Transparency (%) 99.45% Alberdingk acrylic resin (AC 2523) + 99.38 0.25% Byk 346 + 0.3% Tafigel 45 68.8% Alberdingk acrylic resin (AC 2523) + 46.5 30.2% TexFRon 4002 premix + 0.66% Byk 346 + 0.34% Tafigel 45

(49) As can be seen from the transparency measurement, the original color of the wooden sample was visible, the coating which included the flame retardant therein appeared to be translucent, giving rise to a mat finishing of the wooden sample.