GB2155402A - Fire resistant in organically bonded laminates - Google Patents

Abstract

Laminates constructed using layers of reinforcing and/or non-reinforcing materials bonded by at least one layer of a composition of a metal oxide, calcium siliate and phosphoric acid that provides water-resistant phosphate ceramic materials. The products are fire-resistant and intumescent when exposed to heat or direct flame, and produce little or no smoke, while being tough, durable and capable of a decorative and pleasing appearance.

Description

SPECIFICATION Laminates The present invention relates to laminates and more particularly to laminated composites, which are useful as partitions, walls, decorative surfaces, and the like, and processes for their manufacture.

The construction of laminated sheet materials has received extensive study in industry. In particular, materials have been sought which are light in weight, have good appearance, are rugged and durable, and are fireproof or fire-resistant. The latter attributes, in particular, have received special attention. Interior surfaces in buildings, aircraft, automobiles, and the like, are often made of organic materials. When such materials are exposed to heat or fire, toxic fumes are given off and, in many instances, these fumes lead to asphyxiation or result in severe lung damage to those exposed to the fumes. Accordingly, industry has spent a substantial amount of time and effort in attempting to develop products which will have all of the aforementioned desirable attributes, yet which will give off no toxic fumes when subjected to fire.

A number of prior proposals have been made for fire-resistant products. For example, U.S. Patent No.

2,744,589 discloses wall panel units which comprise an insulated panel in which the core is doubly insulated.

The insulating materials are indicated to be rock-wool materials and gypsum sheet. Similarly, U.S. Patent No. 3,466,222 discloses a combination of materials which by themselves would be unsuitable for use as fire retardants; however, in combination, they are capable of forming laminated materials which are stated to be fire-resistant.

Recently, U.S. Patent No. 4,375,516 disclosed rigid, water-resistant phosphate ceramic materials and processes for preparing them. Both foamed and unfoamed materials may be produced according to the procedures set forth in this patent, and the products which have been produced are highly suitable for use as wall boards, ceiling boards, and the like. Further, these products are fire-resistant because they may be produced from totally or primarily inorganic compositions. Nevertheless, the products produced in accordance with the proposal are not suitable for all purposes because they are rigid in nature. Rather than bending under stress the boards tend to break.

Accordingly, one objective of the present invention is to provide inorganic boards which may be flexible yet which are strong and durable.

Another objective of the present invention is to provide fire-resistant boards which are intumescent when subjected to heat or fire, and which produce little or no smoke and fumes.

The present invention is based on the observation that inorganic laminates may be produced which are flexible even though they are constructed using materials that have been previously proposed as suitable to provide rigid products only.

The present invention provides a laminate constructed using one or more layers of a reinforcing and/or non-reinforcing material in combination with one or more layers of a composition that is capable of providing a water-resistant phosphate material. Such material has been described as ceramic. In a preferred embodiment, the product is fire-resistant and intumescent when exposed to heat or direct flame, and produces little or no smoke. Nevertheless, the product is tough, durable and capable of providing a decorative and pleasing appearance.

In one embodiment, the present invention provides a bonded composite structure comprising at least one layer of at least one type of layer material, each said layer of layer material being bonded to a contiguous layer or layers of layer material by a water-resistant phosphate bonding material obtainable by, advantageously obtained from, the reaction of a composition comprising a metal oxide, calcium silicate and phosphoric acid.

In a second embodiment, the present invention provides a fire-resistant bonded composite comprising a plurality of layers of at least one type of layer material, and a plurality of layers of a water-resistant phosphate bonding material obtainable by, advantageously obtained from, the reaction of a composition comprising a metal oxide, calcium silicate and phosphoric acid, each said layer of layer material being bonded to contiguous layers of layer material by said bonding material, said bonded composite being capable of exhibiting intumescent properties when exposed to flame and/or heat.

In a further aspect, the present invention provides a process for forming a bonded composite structure, said process comprising the steps of preparing a layered composition comprising at least one layer of a phosphate bonding composition comprising a metal oxide, calcium silicate and phosphoric acid, said composition being capable of providing a water-resistant phosphate bonding material, and at least one layer of at least one type of material, said composite being arranged such that contiguous layers of said layer material are in contact with intervening layers of said bonding composition, and curing said layered composition, optionally by subjecting it to heat and/or pressure.

Other embodiments and aspects of the invention will be described below.

The unique characteristics of the products which may be produced according to the present invention are attributable in significant part to the use of a phosphate bonding composition which is suitable to provide a water-resistant phosphate ceramic material. Certain such materials have been previously described as being suitable to provide rigid foamed and unfoamed phosphate ceramic products. Surprisingly, however, it has been discovered that, when such compositions are applied as relatively thin bonding layers, they are useful to provide laminated structures which are highly flexible. Examples of compositions which are suitable to achieve this result include those disclosed in U.S.Patent No.4,375,516. That patent discloses that compositions comprising calcium silicate, phosphoric acid and a metal oxide selected from aluminium oxide, magnesium oxide, calcium oxide and zinc oxide, and the hydrates thereof, would react to provide water-resistant phosphate materials; however, it has now been discovered that other metal oxides can also provide water-resistant phosphate materials. Accordingly, there may be used in making the laminates of the present invention any composition comprising a metal oxide, calcium silicate and phosphoric acid, provided that it reacts to provide a water-resistant material, and it will be understood that the term "metal oxide" includes a hydrated metal oxide.

These compositions are coated, preferably in relatively thin layers on the order of ca 1-20 mils (ca 0.025 to 0.5 mm) thick, onto the surface of a layer material which may be a reinforcing or a non-reinforcing material.

The compositions may be applied at normal consistency, or they may be applied as mechanically frothed foams. Where very thin coatings are desired or where lighter-weight laminates are desired, the latter technique is preferred because the foam may be applied at a thickness of ca 1 mil (0.025 mm), after which the thickness is reduced to a thinner dimension as the foam collapses. Further, the bonding composition may be applied, for example in a discontinuous manner, to a portion or portions only of the layer material.

Accordingly, the term "layer" of bonding material is intended to encompass applications in which this material is deposited either in a uniform or in a non-uniform manner, and in a continuous or discontinuous manner.

After applying the bonding composition, the coated material may then be allowed to cure, or it may be covered with a second layer of the same or a different layer material and then allowed to cure. Curing may be achieved under ambient conditions; however, where more dense products are desired, curing may be effected under pressure. In addition, heat may also be applied during curing to accelerate the curing process.

A variety of materials may be used to provide the laminates according to the invention. For example, kraft paper, paper towel, cheese cloth, woven, non-woven, and chopped glass mats, woven non-woven and chopped synthetic materials, for example, polyester or nylon, chopped fibers or various materials, mineral wool, wire mesh and other well-known materials may be used alone or in combination as layer materials. In addition to reinforcing materials, non-reinforcing materials, for example, cementitious materials, may also be used although, in most instances, products which are more rigid in character result.

Particularly effective reinforcing materials for use in combination with the phosphate bonding materials disclosed herein are materials which are disclosed in copending U.S. Application Serial No. 588,576 (European Patent Application No. , Serial No. ), and also in U.S. Patent No. 4,239,519 and patents related thereto, the contents of which are incorporated herein by reference. These references, when considered collectively, disclose a class of material which is referred to herein as "synthetic mica" materials.

In essence, they are asbestos-free papers or sheets which are derived from silicate gels by cation exchange reactions. Materials of this type are known to be relatively unaffected by high temperatures, yet they tend to have good flexibility.

Laminated structures comprising layers of the phosphate bonding materials and synthetic mica sheets have shown remarkable characteristics. For example, when such composites were exposed to direct flame, they not only proved to be fire-resistant and relatively smoke-free, but they also dernonstrated intumescent properties. That is, the exposure of one surface of the structure to direct flame was observed to cause an apparent internal delamination of the structure, resulting in the production of air spaces. Such air spaces are insulative in nature, and dramatic heat differentials have been noted between two sides of a structure tested in this manner.For example, although one side of a relatively thin structure on the order of 0.06 in. (1.5 mm) in thickness was exposed to direct flame at a temperature of about 2050"F (1120 C) for 1 minute, internal swelling occurred and the temperature on the opposite side of the structure was less than 600cm (31 5"C).

This phenomenon is not restricted to laminates constructed using synthetic mica materials. For example, laminates comprising kraft paper also exhibit intumescent properties, and large temperature differentials have been noted for these laminates when tested as described above. The reason why delamination occurs is not clearly understood, although it is believed to be associated at least in part with water contained within the structure.

In addition to intumescent laminates, heat conducting laminates may also be produced by including wire screen as one of the layers. Laminates of this type are effective in conducting heat away from the point of application; thus, these materials are useful for example as heat-conducting gaskets.

The thickness of the laminates produced according to the present invention may vary widely. At the desire of the artisan, structure thickness may be varied from very thin (e.g. 0.03 in. or 0.076 mm) to very thick (e.g., 0.5 in. (12.5 mm) or more). Laminated structures have been produced comprising as few as one layer of one reinforcing material and one layer of phosphate bonding material, or as many as 37 layers of reinforcing layers and 36 layers of phosphate bonding material. This illustration, however, is not intended to limit the number of layers which could be included in a laminate. Furthermore, there is no necessity to restrict the reinforcing materials used in making the laminated structure to a single type, and combinations of reinforcing materials may be used to advantage.

The following Examples illustrate the invention: Example 1 A phosphate bonding material was prepared from the following ingredients: Components Weighf (grams) A1203.3H20 15.0 MgO 8.0 Talc 16.0 75% H3P04 (53.0% P205) 105.0 H3B03 4.0 CaSiOs 100.0 H20 18.0 A phosphate bonding material was produced by preparing a reaction solution comprising the phosphoric acid, the aluminum oxide, and the water. After a clear solution was obtained, and while the solution was still hot, the boric acid was added and the mixture was stirred until it again became clear. The reaction solution was cooled to 4"C and a mixture of the dry components was added.

Each of five two-ply layers of Reichhold Modiglass 2.5X-SM scrim measuring 3 in. x 12 in. (73 x 300 mm) was rapidly provided with 3-mil (0.016 mm) draw downs of the above formula. The five layers were immediately stacked and pressed together for 25 seconds under 556 psi (3.83 MPa) pressure in a press heated to 2500F (327"C). The resulting sheet was strong and water resistant, yet flexible.

The modulus of rupture (MOR) of the laminate, measured essentially according to ASTM D-1037, was 2,100 psi (11.5 MPa); the modulus of elasticity (MOE) value was calculated to be 621 ksi (4.28 GPa); and the NBS fire rating was 0 for smoldering and 2 for flaming, measured essentially according to ASTM E-662-79.

Example 2 The process as set forth in Example 1 was repeated, except that the press was equipped on one face with an embossing plate. The resulting sample picked up the very fine details of the embossing plate.

Example 3 A 1 -mil (0.025 mm) draw down of a phosphate bonding material having the formula set forth in Example 1 was made onto each often separate sheets of kraft paper having dimensions of 12 in. x 12 in. x 0.012 in.

(300 x 300 x 0.3 mm). The ten sheets were immediately stacked together and pressed for 1 minute under 560 psi (3.78 MPa) pressure in a press heated at 200"F (93"C). The resulting sample was strong and flexible, although it was not as flexible as the glass reinforced structure set forth in Example 1. Its MOR value, measured as described in Example 1, was 4,500 psi (31 MPa).

The bonded composite structure was cut into 4 in. x 4 in. (100 x 100 mm) pieces and two of the piece were selected at random for testing. Each piece was placed horizontally on a ring stand and a thermocouple was placed at a location on the bottom surface where the point of a blue propane flame was to be applied. A second thermocouple was placed on the top surface of the laminate directly above the first thermocouple.

When the flame was applied, the temperatures at both thermocouples were recorded with time. Sample 3A increased in thickness from 0.085 in. to 0.199 in. (2.16 to 5.05 mm) when heated for 7 minutes. At the end of that time period, the thermocouple on the flame side of the face recorded a temperature of 1893"F (1034"C) whereas the temperature on the top side was recorded as 622.5"F (328"C). Sample 3B was heated for 6 minutes and showed an increase in thickness from 0.085 in. to 0.166 in. (2.16 to 4.22 mm), and temperatures of 1844"F and 713"F (1007"C and 378"C) on the flame side and top side, respectively, were recorded.

Example 4 A phosphate bonding material as set forth in Example 1 was prepared, except that it comprised 50% by weight of colored No. 17 silica granules of Ottawa Silica Company. This was achieved by mixing the granules with the dry components and then preparing the phosphate bonding material. The filled bonding material was drawn down in a 3-mil (0.076 mm) layer onto one sheet of Johns-Manville glass paper and, at the same time, 3-mil (0.076 mm) draw downs were also prepared on three separate 3-ply sheets of the Modiglass scrim described in Example 1. The three Modiglass layers were stacked on top of one another and the Johns-Manville glass paper was placed on the top of the stack with the granule-filled bonding material facing up.The stacked material was then pressed under 556 psi (3.83 MPa) pressure at 220"F (104"C) for two minutes to give a flexible sheet with good scratch resistance.

Example 5 The procedure as set forth in Example 4 was repeated except that the press was equipped on one face with an embossing plate. The resulting product exhibited fine detail from the embossing plate.

Example 6 A phosphate bonding material was prepared comprising the following components: Components Weight (grams) Al203.3H2O 18.0 MgO 8.0 Talc 16.0 75% H3PO4 (53.0% P205) 108.0 H3BO3 4.0 CaSiO3 100.0 H2O 18.0 The reaction solution was prepared by mixing the phosphoric acid, the water, and the alumina trihydrate and stirring until a clear solution was obtained. The boric acid was added to the resulting warm solution and stirred. After this solution has become clear, the reaction solution was chilled to about 35-39"F (2 to 40C).

To the 148 grams of cold liquid was added, with vigorous stirring, the 124 grams of remaining dry components which had been mixed to provide a uniform material. The resulting mixture was stirred until it had become homogeneous, and it was then placed in an ice bath to prolong the liquid consistency; i.e., to delay the interaction of the components. The pot life of this material could be varied from about 30 seconds to about 7 minutes, depending on the capability of controlling the exothermic reaction temperature in the ice bath.

A synthetic mica sheet was prepared from the following components essentially as described in the aforementioned copending application: Component Weight (grams) Magnesium fluorhectorite 100.0 Bleached redwood cellulose 10.0 fl8" (3 mm) DE glass fibers 5.0 Polymin Pflocculating agent 0.075 Hydraid 777 flocculating agent 0.037 Water The bleached redwood cellulose was dispersed in water by means of a hydropulper and was refined in a Jordan Refiner until a consistency of 500 (Canadian Freeness) was obtained. The refined pulp was transferred to a large, open-head tank and was slurried with the glass fibers. After charging the required amount of water into the tank to get a content of 1.3% solids, the magnesium fluorhectorite floc was added and the mixture was stirred until it was homogeneous.The Polymin P and Hydraid 777 were then added and the composition was immediately flowed onto the forming screen of a Fourdrinier machine. After removing most of the water, the mat was subjected to vacuum in a series of vacuum presses. Residual water was then removed by passing the synthetic mica mat over a heated drum.

A thin coating of the above phosphate bonding material (I) was brushed at a thickness of approximately 10 mils (0.25 mm) onto the surface of a synthetic mica sheet (S). A piece of microlith glass sheet (G), designated SH20/l from Glaswerk Schuller GmbH, was immediately placed in the bonding material and saturated, and the second synthetic mica sheet was placed on top of the glass layer. The assembled materials were placed in a press between glass surfaces and pressed under 250 psi (1.72 MPa) pressure for five minutes at 170"F (77"C). After pressing was complete, the pressed composite was conditioned at 1700F (77 C) for several additional minutes to remove water, giving a product which was strong and flexible.

It was noted that, because of the porous nature of the glass sheet, the bonding material did not have to be applied on both sides of the glass sheet. The bonding material was capable of passing through (saturating) the glass layer under pressure such that both contiguous layers of synthetic mica could be bonded to the glass through a single application of bonding material. In this and the following examples the saturation is indicated by (GI) or (IG). Accordingly, the structure of this example had the laminate order S(IG)S.

Example 7 A process similar to that of Example 6 was repeated except that glass sheets constituted the exterior layers and the composite material had the structure (Gl)S(IG). The glass sheets were bonded with the phosphate bonding material to the single internal layer of synthetic mica sheet by placing the composite in a press that was equipped with shallowly patterned embossing plates. The plates provided a fine texture in a desired design to the surface of the laminate.

Example 8 The procedure of Example 7 was repeated, except that the composite material was placed between a foamed silicone rubber pad and male or female metal molds bearing a design. This resulted in the production of molded products with deeply embossed images.

Example 9 A series of laminates was prepared essentially as described in Example 6, each sample containing synthetic mica, phosphate bonding material, and, optionally, glass sheet. As in Example 6, the phosphate binder saturated the glass sheet such that, when included internally in a laminated structure, the binder served to bond contiguous layers of synthetic mica even though the binder may have been applied to only one face of the glass sheet, or to only one of the contiguous synthetic mica sheets.

MOR values were determined according to ASTM D-1037 whereas MOE values were calculated by standard mathematical means from the MOR values. The structures of each laminate are indicated, top to bottom. Unless otherwise indicated, the bonding material was applied in 8-mil (0.2 mm) draw downs, and SH 20/l glass sheet was used.

Sample Structure MOR (psi) MOE (ksi) 9A SISISIS 1448 164 9B S(IG)S(IG)S(IG)S 1568 175 9C* S(IG)S(IG)S(IG)S 1682 211 9D (Gl)S(IG)S(IG)S(IG)S(IG) 3449 576 * = I applied as a 12 mil (0.3 mm) draw down.

The metric equivalents of the above results are as follows: Sample MOR (MPa) MOE (GPa) 9A 9.98 1.13 9B 10.81 1.21 9C 11.60 1.45 9D 23.78 3.97 The results for these samples show a marked increase in strength when the laminate is faced with the glass sheet.

Sample Structure MOR (psi) MOE (ksi) 9E (Gl)SISISIS(IG) 3214 558 9F* (Gl)SISISIS(IG) 3906 568 9G (GI)SISIS(IG) 3247 610 9H (Gl)SIS(IG) 3500 582 ** = SH 50/l glass sheet used in place of SH 20/l glass sheet.

The metric equivalents of the above results are as follows: Sample MOR (MPa) MOE (GPa) 9E 22.16 4.05 9F 26.93 3.92 9G 22.39 4.21 9H 24.13 4.01 These results, when compared to the values obtained for sample 9D, suggest that the facing scrim sheets contribute substantially more to the strength of the laminate than do the internal glass sheets.

The following structures were also prepared: Sample Structure MOR (psi) MOE (ksi) 91 SISIS 1713 323 9J S(IG)S(IG)S 2320 385 9K IS(IG)S(IG)SI 2355 471 The metric equivalents of the above results are as follows: Sample MOR (MPa) MOE (GPa) 91 11.81 2.23 9J 15.60 2.65 9K 16.24 3.25 Example 10 This example will illustrate the results when various samples were heated with a propane torch as described in Example 3. The results are indicated below for laminates having various components and structural arrangements.

Heating caused noticeable changes to the laminates, and these changes became more pronounced as the number of layers increased. For example, when heat was applied to a single synthetic mica sheet, only a small expansion of the sheet was seen. However, when two or more synthetic mica and phosphate bonding layers (with or without glass reinforcing) were utilized, blistering became more pronounced. The effect with the thicker samples, as shown below, was to provide good insulative effects. The table indicates the increase in thickness which was induced in each sample by the heating.

Samples were constructed of layers of SH 20/l glass sheet and/or synthetic mica bonded together with phosphate bonding material substantially as described in Example 9. The resulting laminates were unembossed. They were designated as Samples 10Athrough 10H and the "Structure" column lists the laminar sequence from top to bottom.

Thickness Change (inch) Sample Structure Initial Final Increase 10A S 0.027 0.038 0.011 10B ISI 0.034 0.125 0.091 lOC (GI)S(IG) 0.037 0.130 0.093 10D ISISI 0.055 0.150 0.095 10E (GI)S(GI)S(IG) 0.063 0.173 0.110 10F ISISISI 0.073 0.194 0.121 10G (Gl)S(Gl)SIS(IG) 0.085 0.210 0.125 10H (GI)S(GI)S(GI)S 0.084 0.250 0.166 The metric equivalents of the above results are as follows:: Thickness Change (mum) Sample Initial Final Increase 1 OA 0.69 0.97 0.28 10B 0.86 3.17 2.31 10C 0.94 3.30 2.36 1 OD 1.40 3.81 2.41 10E 1.60 4.39 2.79 10F 1.86 4.93 3.07 10G 2.16 5.33 3.17 10H 2.13 6.35 4.22 Temperature differentials were as follows, measured at the indicated time intervals. Measurements were made by subtracting the temperature at the top-side thermocouple (Ts) from the flame-side thermocouple (Fs) to obtain the differential (D).

Temperatures f F) as Indicated Time Intervals (seconds) Sample Location 15 30 60 120 180 10A Fs 2163 2180 2196 - Ts 1017 1090 1107 - D 1146 1090 1089 - lOB Fs 2195 2222 2239 - Ts 855 1032 1024 - D 1340 1190 1215 - 10C Fs 2275 2329 2314 2291 2304 Ts 454 1064 1064 1074 1068 D 1821 1254 1254 1217 1236 10D Fs 1862 1997 2016 2038 2059 Ts 183 344 794 866 869 D 1679 1653 1222 1172 1190 10E Fs 1897 2042 2043 2072 2079 Ts 160 237 552 736 756 D 1737 1805 1491 1336 1323 10F Fs 2060 2106 2162 2192 2175 Ts 179 199 365 714 726 D 1881 1907 1797 1478 1449 10G Fs 2182 2219 2216 2253 2262 Ts 169 182 281 658 687 D 2013 2037 1935 1595 1575 10H Fs 2051 2029 2073 2149 2166 Ts 158 176 221 584 622 D 1893 1853 1852 1565 1504 The temperatures in "C for the above results are as follows:: Temperatures pF) as Indicated Time Intervals (seconds) Sample 15 30 60 120 180 10A 1184 1193 1202 - 547 588 597 - 637 605 605 - 10B 1202 1217 1226 - 457 556 551 - 745 661 675 - 10C 1246 1276 1268 1255 1262 234 573 573 579 576 1012 703 695 676 686 10D 1016 1092 1102 1114 1126 84 173 423 463 465 932 919 679 651 661 10E 1036 1117 1117 1133 1137 71 114 289 391 402 965 1003 828 742 735 10F 1127 1152 1183 1200 1191 82 93 185 379 386 1045 1059 998 821 805 10G 1194 1215 1213 1234 1239 76 82 138 348 364 1118 1132 1075 886 875 10H 1122 1109 1134 1176 1186 70 80 105 307 328 1052 1029 1029 869 858 These results illustrate that heating causes the laminates to swell, thereby exhibiting intumescent properties.

Example 11 The procedure as set forth in Example 6 was repeated using synthetic mica, Schuller 20/l glass scrim, Burlington No. 1653 Lenoweave (16 x 8) glass scrim (abbreviated "B") and/or galvanized iron wire window screen (W) having 14 strands v. 17 strands per square inch (5.5 x 6.7 per sq. cm). The following samples were prepared: Sample Structure 11A SIS 11B ISI 11C S(IG)S 11D (GI)S(IG) 11E S(IB)S 11F S(IW)S The products were tested for tensile strength and also for flexibility. Tensile strengths were determined essentially according to ASTM F-152 using Type 1 specimen sizes on an Instron tensile tester at 1 in./min (25.4 mm/min) crosshead speed and a chart speed of 1 in/min; however, the samples were not preconditioned. The samples were cut in a 1/2-inch (12.7 mm) dumbbell shape, with the exception of sample 1 which was cut in a 1-in. (25.4 mm) dumbbell shape.

The following results were obtained: Sample Results Lbs. at break psi 11A 24.7 (1.5) 1030 (106) 11B 11.6 (2.4) 777 (282) 11C 30.0 (3.7) 1280 (240) 11D 24.5 (1.8) 1210 (180) 11E 45.1 (2.3) 1880 (180) 11F 146 (11) 5830 (170) The metric equivalents of the above results are as follows: Sample Results Kg at break MPa 11A 11.20 (0.68) 7.10 (0.73) llB 5.26 (1.09) 5.36 (1.94) 11C 13.61 (1.68) 8.83 (1.65) 11D 11.11 (0.82) 8.34 (1.24) 11E 20.45 (1.04) 12.96 (1.24) 11F 66.2 (4.99) 40.20 (1.17) The values reported are an average of three measurements, with the numbers in parentheses being the difference between the highest and lowest numbers recorded for each set.

Flexibility was determined essentially according to ASTM F-147, commonly referred to as a "mandrel bend test." Samples 1 lA-lID failed the test using a 1-in. (25.4 mm) mandrel; sample 11 F passed using a 1-in.

mandrel; and sample 1 lE passed using a 7/8-in. (22.23 mm) mandrel. None of the samples was preconditioned.

Example 12 This example will illustrate the heat conductivity which results on including a metal screen in a laminate.

Laminate C, having the structure (Gl)S(Wl)S, was prepared in the usual manner, except that thermocouples were incorporated into the structure by placing them on the upper surface of the upper synthetic mica sheet.

They were then cured in place by applying the upper (GI) layers. The thermocouples were located at measured distances from the point of flame application either in the wire direction (WD) or diagonally across the mesh (oblique), as follows: Distance Thermocouple Location ins. mm (approx.) TC 1 flame application point - TC2 oblique 2 50 TC3 oblique 4 100 TC 4 oblique 5 125 TC 5 oblique 6 150 TC 6 WD 4 100 Laminate C was prepared using galvanized iron wire as described in Example 11 whereas Laminate B was prepared to contain comparable copper wire. Laminate A, which contained no wire, was prepared as a control. The following temperatures were recorded.

Temperatures Recorded Time TIC 1 TC2 TC3 (min A B C A B C A B C 0 80 80 78 81 80 78 81 81 79 3 1989 1892 1911 166 191 210 99 101 96 10 1920 1865 1919 161 219 255 100 108 108 15 1861 1877 1871 200 237 261 102 110 111 TC4 TC5 TC6 A B C A B.C A B C 0 81 81 79 81 81 79 81 80 78 3 94 95 89 90 92 86 116 156 144 10 95 99 96 91 94 91 116 163 168 15 96 100 98 92 95 93 121 172 169 The temperatures in C for the above results are as follows: Time TIC 1 TC2 TC3 (mid) A B C A B C A B C 0 27 27 26 27 27 26 27 27 26 3 1087 1033 1044 74 88 99 37 38 36 10 1049 1018 1049 72 104 124 38 42 42 15 1016 1025 1022 93 114 127 39 43 44 Time TC4 TC5 TC6 (mix) A B C A B C A B C 0 27 27 26 27 27 26 27 27 26 3 34 35 32 32 33 30 47 69 62 10 35 37 36 33 34 33 47 73 76 15 36 38 37 33 35 34 49 78 76 These results indicate that a laminated screen will assist in dissipating the heat from the point of application, and that copper wire will dissipate the heat more efficiently than will galvanized iron wire.In addition, by comparing the results for TC5 and TC6, it is seen that heat is more efficiently conducted in a wire direction as opposed to an oblique direction.

Example 13 This example will illustrate the preparation of a sample which is not cured under heat and pressure. A 6-mil coating of the bonding composition described in Example 1 (about 125 g) was appled to a 12 in. x 12 in.

(approx 300 x 300 mm) piece of 2.5X-SM Modiglass scrim, and a second piece of scrim was placed on top of the coating. The layered material was briefly compressed to drive the bonding composition into the respective scrim layers and the composite was allowed to cure under ambient conditions. Curing was effected in about 5 minutes.

Example 14 This example will illustrate the application of a foamed bonding composition to a layer of scrim. The bonding composition was prepared as described in Example 1 and mixed for about 25 seconds. To the mixed material (268 g) was added 10.1 g (3.8%) of Millifoam surfactant from Onyx Chemical Co. and the foam was produced by mechanically mixing with an air stirrer for 40 seconds. A 3-mil (0.076 mm) coating was applied to both surfaces of a 12 in. x 12 in. (about 300mm square) piece of 7.5X-SM Modiglass scrim, the total application by weight being about 829. The coated scrim was pressed for 25 seconds at 180"F (82"C) to give a cured sheet.

Claims (38)

1. A bonded composite structure comprising at least one layer of at least one type of layer material, each said layer of layer material being bonded to contiguous layers of layer material by a water-resistant phosphate bonding material obtained from the reaction of a composition comprising a metal oxide, calcium silicate and phosphoric acid.

2. Afire-resistant bonded composite comprising: a plurality of layers of at least one type of layer material, and a plurality of layers of a water-resistant phosphate bonding material obtained from the reaction of a composition comprising a metal oxide, calcium silicate and phosphoric acid, each said layer of layer material being bonded to contiguous layers of layer material by said bonding material, said bonded composite being capable of exhibiting intumescent properties when exposed to flame and/or heat.

3. The invention as claimed in claim 1 or claim 2 hereof wherein said metal oxide is selected from aluminum oxide, magnesium oxide, calcium oxide and zinc oxide, and the hydrates of said oxides.

4. The invention as claimed in claim 1 or claim 2 hereof wherein said metal oxide is aluminum oxide trihydrate.

5. The invention as claimed in claim 1 or claim 2 hereof wherein said metal oxide is magnesium oxide.

6. The invention as claimed in any one of claims 1 to 5 hereof wherein said bonding material is in the form of a substantially uniform layer.

7. The invention as claimed in any one of claims 1 to 5 hereof wherein said bonding material is in the form of a substantially discontinuous layer.

8. The invention as claimed in any one of claims 1 to 7 hereof wherein said bonded composite comprises a synthetic mica layer material.

9. The invention as claimed in any one of claims 1 to 8 hereof wherein said bonded composite comprises a woven, a non-woven or a chopped glass layer material.

10. The invention as claimed in any one of claims 1 to 9 hereof wherein said bonded composite comprises a woven, a non-woven or a chopped synthetic layer material.

11. The invention as claimed in any one of claims 1 to 10 hereof wherein said bonded composite comprises a kraft paper layer material.

12. The invention as claimed in any one of claims 1 to 11 hereof wherein said bonded composite comprises a wire mesh layer material.

13. A structure as claimed in claim 1, substantially as described in any one of the numbered samples herein.

14. A process for forming a bonded composite structure, said process comprising the steps of preparing a layered composite comprising (a) at least one layer of a phosphate bonding composition comprising a metal oxide, calcium silicate and phosphoric acid, said composition being suitable to provide a water-resistant phosphate bonding material, and (b) at least one layer of at least one type of layer material, said composite being arranged such that contiguous layers of said layer material are in contact with intervening layers of said bonding composition, and (c) curing said layered composition, optionally by subjecting it to heat and/or pressure.

15. The invention as claimed in claim 14 hereof wherein said metal oxide is selected from aluminum oxide, magnesium oxide, calcium oxide and zinc oxide, and the hydrates of said oxides.

16. The invention as claimed in claim 14 hereof wherein said bonding composition comprises aluminum oxide trihydrate.

17. The invention as claimed in claim 14 hereof wherein said bonding composition comprises magnesium oxide.

18. The invention as claimed in any one of claims 14 to 17 hereof wherein said bonding composition is applied at a thickness of from 1 to 20 mils (0.025 to 0.5 mm).

19. The invention as claimed in any one of claims 14to 18 hereof wherein said bonding composition is applied as a mechanically frothed foam.

20. The invention as claimed in any one of claims 14to 19 hereof wherein said bonding composition is applied as a substantially continuous layer of material.

21. The invention as claimed in any one of claims 14to 19 hereof wherein said bonding composition is applied as a substantially discontinuous layer of material.

22. The invention as claimed in any one of claims 14to 21 hereof wherein at least one of said layer materials is a synthetic mica layer material.

23. The invention as claimed in any one of claims 14to 22 hereof wherein at least one of said layer materials is a woven, a non-woven or a chopped glass layer material.

24. The invention as claimed in any one of claims 14to 23 hereof wherein at least one of said layer materials is a woven, non-woven or a chopped synthetic layer material.

25. The invention as claimed in any one of claims 14 to 24 hereof wherein at least one of said layer materials is a kraft paper layer material.

26. The invention as claimed in any one of claims 14 to 25 hereof wherein at least one of said layer materials is a wire mesh layer material.

27. A process as claimed in claim 14, carried out substantially as described in any one of the numbered samples herein.

28. A laminate comprising at least one first layer bonded to at least one second layer by a water-resistant phosphate bonding material obtainable by the reaction of a composition comprising a metal oxide, calcium silicate and phosphoric acid.

29. A laminate as claimed in claim 28, wherein the bonding material is obtained by the reaction of the specified composition.

30. A laminate as claimed in claim 28 or claim 29, which also comprises a layer that is permeated by the phosphate bonding material.

31. A laminate as claimed in claim 30, wherein the peremeated layer is a glass fibre layer.

32. A laminate as claimed in any one of claims 28 to 31, wherein said first and second layers are of the same material.

33. A laminate as claimed in claim 32, which contains several such layers.

34. A laminate as claimed in claim 33, wherein said layers are of a synthetic mica.

35. A laminate as claimed in any one of claims 28 to 31, wherein the material of at least one first layer differs from that-of at least one second layer.

36. A laminate as claimed in claim 35, which comprises several such layers.

37. A laminate as claimed in claim 36, wherein the layers are of at least three different materials.

38. Any new feature or combination of features hereinbefore described.