The present invention relates to a structure as defined in the preamble of claim 1. A further object of the invention is a procedure as defined in the pre¬ amble of claim 19.

Previously known are e.g. laminated and layered structures, so-called reinforced plastic struc- tures, which are produced by saturating with organic resins such as polyester, epoxide etc. Such structures are not fire resistant but, on the contrary, combusti¬ ble.

The object of the present invention is to produce a completely new type of structure which can be used in a manner and in applications corresponding to organic resins, e.g. in reinforced structures with a fibrous framework, but which new structure has a fire resistance of an order totally different from reinfor- ced plastic structures and is also cheap to manufactu¬ re, strong, durable and light.

A specific object of the invention is to pro¬ duce a fire resistant coat, a hard or an elastic wall, a laminated board and/or laminated structure with or without thermal and/or sound insulation, which can be used e.g. in mechanical engineering, building, boat, vehicle, aeroplane and shipbuilding industries.

The structure of the invention is character¬ ized by what is presented in claim 1. The procedure of the invention is characterized by what is presented in claim 19.

According to the invention, the structure comprises a layer of inorganic silicate-oxychloridic cement and/or inorganic silicate-oxysulphatic cement. In addition to its most important property, fire resistance, such cement is light, hard, strong and water resistant. When wet, it adheres well to any other

structure, so it can be used as a coating and in dif¬ ferent laminated structures to join the laminae togeth¬ er without the need to use any other adhesive materi¬ als. It has been found in fire tests that when the material is heated on a flame to high temperatures, e.g. to a temperature of 900 °C, an endothermic reac¬ tion and a cooling of the thermal wave occur in the material, with the effect that the temperature in the material cannot rise to a critical level. Furthermore, the cement does not develop any detrimental gases. Though it is fire resistant, the material contains no asbestos, unlike certain previously known fire resis¬ tant structures. The presence of sodium silicate in the material protects it against dissolution in water and enhances its endothermic feature in the combustion process. Moreover, the material has a very low coeffi¬ cient of thermal expansion, which means that it pre¬ serves its shape and is not deformed in fire. As the structure is a reinforced laminate, it can be manufac¬ tured in open or closed tools under minimum pressure because it adapts to the given shape, allowing large boards to be manufactured in one piece. As compared with a corresponding reinforced plastic structure, the structure of the invention weighs only half as much. For instance, conventional reinforced plastic laminate of a thickness of 6 mm weighs 11 - 12 kg/m ² , whereas corresponding reinforced laminate produced according to the invention weighs about 8 - 9 kg/m ² . In an embodiment of the structure, the sili- cate-oxysulphatic cement is composed of water (H,0) , magnesium sulphate (MgSO , magnesium oxide (MgO) and sodium silicate (waterglass) . Instead of magnesium sulphate, ;Lt. is possible to use magnesium chloride (MgCl,) , in which case the resulting material is sili- cate-oxychloridic cement.

In an embodiment of the structure, the cement

contains about 10 - 20 w-% of water (H ₂ 0) , about 40 - 60 w-% of magnesium oxide (MgO) and ≤ 10 w-% of sodium silicate. In this case the cement contains about 30 - 40 w-% of magnesium sulphate (MgSO or alternatively magnesium chloride (MgCl,) .

In an embodiment of the structure, the layer is a coating formed from said silicate-oxychloridic cement and/or slicate-oxysulphatic cement, which is applied directly onto the surface of the base material to be protected. The coating can be applied by spraying e.g. onto the metal surface of the bulkhead of a ship. In an embodiment of the structure, the struc¬ ture consists of a fibre-reinforced laminate comprising a fibrous reinforcement which is impregnated with a layer of bonding agent consisting of silicate-oxychl¬ oridic cement and/or silicate-oxysulphatic cement as mentioned above. In such laminates, the fibrous rein¬ forcement used may consist of a non-alkaline glass fibre mat, felt and/or textile placed in one or more layers on top of each other. The laminate can be pro¬ vided with a top layer consisting of organic resin. The fibrous reinforcement is preferably at least partially bonded together with the organic resin of the top layer and, on the other hand, preferably to a depth about half its thickness, with the layer of inorganic bonding agent, so that the organic and inorganic layers are joined together.

In an embodiment of the structure, the organic resin of the top layer is a polyester gelcoat rendered hard and more fire resistant by means of aluminium hydroxide (Al(OH) ₃ ). Polyester gelcoat is used as in reinforced plastic structures as a top layer to produce a smooth and glossy surface with an esthetic appear¬ ance, e.g. in the form of a film of a thickness of about 1 mm.

In an embodiment of the structure, the struc¬ ture comprises a thin metal sheet, such as a metal

foil, which is bonded by means of a bonding cement onto the surface of the structure to form a coat on it. The metal foil adheres well to the surface of a wet cement layer. The coat used may be any suitable metal film which gives the desired esthetic appearance e.g. to a wall element.

In an embodiment of the structure, the struc¬ ture comprises a layer of insulating material consist¬ ing of foamed resin and bonded together with the struc- ture by a cement as mentioned above. The insulating layer of foamed resin may consist e.g. of foamed pheno¬ lic resin, polyurethane or styrol. Foamed organic resin as such has a low fire resistance, but when provided with a cement layer as mentioned above, its fire resis- tance is substantially improved.

In an embodiment of the structure, the struc¬ ture comprises a layer of fibrous insulating material consisting of inorganic fibre and bonded together with the structure by said cement. The layer of insulating material may consist of fibre glass, mineral wool, rock wool or the like. Preferably the layer of insulating material consists of so-called laminated wool, in which the fibre direction is essentially the same as the direction of the board. An uninflammable laminate made from a fibre glass fabric impregnated with a bonding cement together with a layer of insulating material attached to it with a bonding agent forms an uninflam¬ mable sound- and heat-insulating rigid laminated board which can be used as a planar or curved wall element in a wide range of applications.

In an embodiment of the structure, the struc¬ ture is a three-layer structure which has a platelike middle layer of insulating material and two laminates reinforced with a fibrous reinforcement and impregnated with said bonding cement, the two laminates being lami¬ nated onto opposite sides of the middle layer.

Correspondingly, in the procedure of the in-

vention for the manufacture of a laminated structure with improved fire resistance, a layer of inorganic silicate-oxychloridic cement and/or inorganic silica- te-oxysulphatic cement is formed in the structure. The hardening of the cement can be accelerated by subject¬ ing the structure to a heightened temperature of the order of about 40 - 80 C° . The laminates and laminated structures are manufactured layer by layer in a manner similar to the manufacture of reinforced plastics, i.e. on the wet-on-wet principle, which means that the manu¬ facture can be implemented using a continuous industri¬ al production process.

A special advantage of the invention is that it makes it possible to produce structures resembling reinforced plastic structures but which structures, e.g. wall, shell and laminated structures, are incom¬ bustible in accordance with the IMO Resolution norm and DIN norm 4102. These structures can be used e.g. in buildings and ships e.g. as wall, ceiling and panel elements etc. The structure of the invention can be used to form e.g. an entire cabin module of a so-called sanitary cubicle type, complete with WC and shower equipment. The norms applying to ships stipulate that the structures should be uninflammable in accordance with the IMO-Res. B15 norm, in other words, that they should withstand a temperature of 900 C° for 15 minutes without catching fire. Reinforced plastic structures do not meet this norm, which is why it has not been possi¬ ble to use prefabricated reinforced plastic modules in ships, whereas according to the invention the struc¬ tures can be made such that they even meet the demands of the IMO-Res. B30 norm, which is more stringent than the B15 norm, in other words, the structures endure fire at 900 C° for 30 minutes and even longer. The structure of the invention, containing a layer of hardened silicate-oxychloridic or silicate- oxysulphatic cement, thus solves the problem of manu-

facturing fire- and waterproof impregnated structural materials subject to physical influences. It is suf¬ ficiently hard and light, and together with an unin¬ flammable insulating material (heat or sound insula- tion) it can be used in the form of planar or curved boards, as laminated walls usable in containers, cab¬ ins, kiosks, doors, partitions, etc. When attached directly to the panel or steel structure of a ship's bulkhead, the laminated structures provide an excellent insulation and fireproofing. The structures of the invention are also usable in cooling systems.

Other features of the procedure are presented in the claims and in the following detailed description of the invention. In the following, the invention is described in detail by referring to the attached drawings, in which

Fig. 1 presents in diagrammatic form a cross-section of a first embodiment of the structure of the invention, the structure being a coating,

Fig. 2 presents in diagrammatic form a cross-section of another embodiment of the structure of the invention, in which the structure is a reinforced laminated board provided with a decorative top layer, Fig. 3 presents in diagrammatic form a cross-section of a third embodiment of the structure of the invention, in which the structure is a reinforced laminated board provided with a decorative metal foil coating, Fig. 4 presents in diagrammatic form a cross-section of a fourth embodiment of the structure of the invention, in which the structure is a panel of laminated structure with a layer of insulating materi¬ al, Fig. 5 presents a fifth embodiment of the structure of the invention, in which the structure is a panel of laminated structure with a layer of insulating

material,

Fig. 6 illustrates the change in the temper¬ ature in an oven used to apply a thermal load to a laminated panel tested in test example 3, as a function of time during the test,

Fig. 7 illustrates the change in the temper¬ atures measured at measuring points on the external surface of a laminated panel as tested in test example 3, as a function of time during the test, Fig. 8 illustrates the change in the temper¬ ature in an oven used to apply a thermal load to a door panel tested in test example 4, as a function of time during the test, and

Fig. 9 illustrates the change in the temper- atures measured at measuring points on the external surface of the door panel tested in test example 4, as a function of time during the test.

Fig. 1 shows a fire resistant protective structure implemented in the form of a coat l applied in a thin layer onto a base material e.g. by spraying and hardened on the surface of the base material 2. The base material 2 may consist of any object to be pro¬ tected, such as the body or bulkhead of a ship, a wall of a building or the like. The fire resisting property is achieved by the coating layer, which may consist of inorganic silicate-oxychloridic cement and/or inorganic silicate-oxysulphatic cement. The silicate-oxysulphatic cement is composed of water (H ₂ 0) , magnesium sulphate (MgSO , magnesium chloride (MgCl , magnesium oxide (MgO) and sodium silicate (waterglass) .

The consistency of the cement is preferably such that it contains 10 - 20 w-% of water, about 40 - 60 w-% of magnesium oxide, and at most 10 w-% of sodium silicate. In addition to these, the mixture also con- tains about 30 - 40 w-% of magnesium sulphate or alter¬ natively magnesium chloride, depending on whether it is to form silicate-oxychloridic cement or silicate-oxy-

sulphatic cement.

Fig. 2 shows a rigid laminated board formed by reinforcing the bonding agent 1, which consists of silicate-oxychloridic cement or silicate-oxysulphatic cement corresponding to the coat in the example in fig. 1, with fibrous reinforcements 3. These consist of non-alkaline, in this example two fibre glass mats. The fibre glass mat 3 is sunk in the cement, i.e. impreg¬ nated with it. On the surface of the board there is a top layer 4 consisting of organic polyester resin. This layer is preferably formed by using a polyester gelcoat modified with aluminium hydroxide (Al(OH) ₃ ) . The topmost fibre glass mat 3 is partially, i.e. through one half of its thickness, bonded together with the organic resin of the top layer 4 and, on the other hand, it is also bonded together with the layer of inorganic bond¬ ing agent 1 through about one half of its thickness, thus joining the organic and inorganic layers to each other so that they constitute a continuous structure. The structure is formed on the wet-on-wet principle.

Fig. 3 shows a reinforced laminated board in which a fibre glass mat 3 is sunk in bonding cement 1 as described under fig. 1. A metal foil is laid on top of the bonding agent layer 1 to give the structure an esthetically pleasing appearance. A metal foil or any kind of sheet adheres well to the bonding cement 1 of the invention without the use of any other coupling agent.

Fig. 4 shows a laminated sandwich board com- prising a layer of insulating material 6; 7 bonded together with a rigid sheetlike surface layer by means of bonding cement 1 e.g. as described in connection with fig. 2. The insulating layer may be an insulation layer 6 consisting of foamed resin or a fibrous insula- tion layer 7 consisting of inorganic fibre and it is bonded together with the surface sheet structure by the cement 1. The insulation layer may consist e.g. of

phenolic resin, polyurethane or styrol. The fireproof fibrous insulation layer 7 again may consist of fibre glass, mineral wool, rock wool or the like. Preferably this insulation layer 7 contains so-called laminated wool, in which the fibre direction is essentially the same as the direction of the board.

Fig. 5 shows a three-layer structure compris¬ ing a platelike middle layer 6; 7 of insulating materi¬ al and two laminates reinforced with a fibrous rein- forcement 3 and impregnated with said bonding cement 1, laminated onto opposite sides of the middle layer so that the middle layer 6, 7 is contained between the two laminates 3. The laminates 3 may be reinforced with a non-alkaline glass framework and they can be provided with a gel-coat top layer 4 or a metal foil 5 as de¬ scribed in connection with the applications of fig. 2 or 3. The layer of insulating material 6, ^• 7 may consist of a fibrous or foamed insulating material as in the previous example. Such a laminated structure provides excellent insulation against fire, moisture, heat and noise.

In each of the examples described, the fire resistance of the structure can be adjusted simply by varying the thickness of the cement layer, e.g. by adding more cement layers.

EXAMPLE

To produce a laminated board having an area or 1 m ² and a thickness of 6 mm and either a flat or a curved shape (e.g. prefabricated cabin with WC and shower) and covered with a protecting top layer made of polyester, the following materials are needed:

(a) 3 non-alkaline glass mats, each weighing 450 g/m ² and measuring 1000x1000 mm. (b) 2 non-alkaline fibre glass felts 40-60 g/m ² , lOOOx- 1000 mm

(c) water, 1 kg

(d) magnesium chloride (MgCl ₂ ) 47 %, 2.5 kg,- or

(e) magnesium sulphate (MgSO 49 %, 2.5 kg

(f) magnesium oxide - alkali (MgO) 5 kg

(g) sodium silicate (waterglass) «45 Bo, 0.5 kg (h) modified polyester (aluminium hydroxide 0.3 kg + polyester Chromos S020 0.8 kg) , contact and accelera¬ tor.

The product is manufactured as follows: (a) magnesium chloride is mixed in cold water, or magnesium sulphate is mixed in warm water (-60 C°),

(b) saline solution prepared in advance is poured grad¬ ually into a container together with sodium silicate, stirring, until it has dissolved completely, and then both liquids are poured into a mixer (this is the con¬ tact liquid) ,

(c) the magnesium oxide is poured into the contact liquid while stirring slowly, stirring is continued until the mass of bonding agent becomes completely compact,

(d) the surface of a mold beforehand covered with a layer of release wax is first covered with modified polyester by means of a roller, whereupon a non-alka¬ line glass felt is pressed onto the wet surface, (e) a thin layer of modified polyester is sprayed onto the glass fibre mat and the mat is pressed onto the wet side of the mold,- after a gel has been formed (this takes about 15 min) , the bonding cement is applied using a roller, (f) the glass fibre mat layers are impregnated with the bonding cement. Using a polyethylene film placed on the surface, the air is then forced out from the top sur¬ face and the surface is smoothed. After the polyethyl¬ ene film has been removed, the wet panels are pressed against the wet surface of the mold, the air is forced out and the required shape is achieved. The film may be left in place until the product has been hardened,

whereupon it can be removed.

(g) if the product is manufactured using silicate oxy- chloride, complete hardening takes 12 - 14 hours at a temperature of 18 - 30 C° . A product containing sili- cate oxysulphate can be treated in a hot press or cham¬ ber at 60 - 80 C°, which will accelerate the hardening process to 10 - 15 min. In a heat chamber (approx. 40 - 50 C°) the hardening would take somewhat longer (2 - 6 hours) . After the laminate has been removed from the mold, it is ready for processing (by cutting, grinding or polishing) , although the product will only reach its full degree of hardness in 20 days. A 6 mm thick Vazomat laminate weighs about 8 - 9 kg/m ² .

If a laminated-board panel were to be made from sheets both sides of which are provided with rein¬ forced laminates formed with a bonding cement and which have a 20 mm thick heat insulation of 50 - 80 kg/m ³ mineral wool or fibre glass, then instead of a 450 g/m ² non-alkaline fibre glass mat, four 300 g/m ² mat sheets would be used and the procedure would be repeated for each side of the product. A laminated panel of a thick¬ ness of 25 mm would have a mass of about 10 kg/m ² and it would reach a fire resistance according to the DIN 4102 and IMO Resolution B30 and F300 standards, which require an endurance of over 30 minutes.

Below are brief descriptions of fire resis¬ tance tests performed on structures produced according to the invention.

TEST EXAMPLE 1

A VAZOMAT laminated board as provided by the invention was subjected to a combustibility test ac¬ cording to the IMO Resolution norm A.472 (XII) (Test report DN 5/530-649/94-A) . The material was a 10 mm thick sheet made of non-alkaline fibre glass mat, inor¬ ganic bonding agent based on oxysulphatic cement and about 10% aluminate bonding agen . According to the

test report, the material was found to be non-combusti¬ ble in accordance with IMO Res. A.472.

TEST EXAMPLE 2 An IRSOPAN laminate product as provided by the invention was subjected to a surface spread of flame test according to norm BS 476: Part 7: 1971. (Test report number 5/530-649/94-B ZMRK-Institute for Research and Quality Control; Ljubljana, Slovenia) . The product under testing was a panel consisting of polyes¬ ter resin, fibre glass mat and bonding agent. The com¬ position of the panel was as follows:

- polyester gelcoat Chromoplast S-202 Vazomat 0.5 kg/m ²

- non-alkaline glass fabric 60 g/m ² - polyester bonding agent Chromoplast S-202 Vazomat 0.5 kg/m ²

- two layers of non-alkaline fibre glass mat 450 kg/m ²

- oxysulphatic bonding agent Vazomat 1 kg/m ²

- aluminate bonding agent Vazomat 1 kg/m ² . The limit values for the best class according to the norm, class 1, are: flame propagation 165 mm in 1.5 min and final propagation in 10 min.

The test results for six samples were.- flame propagation 25 - 40 min in 1.5 min and final propaga- tion 25 - 40 mm in 10 min.

Thus, the test yielded a result according to which the product meets the limit values of the best "Class 1" according to norm BS 476:Part 7: 1971.

TEST EXAMPLE 3

A laminated board "IRSOPAN Mineral Sandwich for "B15" Class Bulkhead" was subjected to a fire re¬ sistance test according to norm IMO Res. A 754(18) for class "B" bulkhead classification. (Test report no. 5/530-649/94-C, ZMRK-Institute for Research and Quality Control; Ljubljana, Slovenia) .

The test specimen consisted of three panels of

which two had a width of 950 mm and one 465 mm. The thickness of the panel was 50 mm. The panels were made of Novoterm TIP/L glass wool with polyester gelcoat, fibre glass mat, polyester resin, oxysulphatic bonding agent and aluminate bonding agent. In detail, the mate¬ rials were as follows: Insulation: manufacturer: Novoterm, Novo Mesto, Slovenia commercial designation: NOVOTERM TIP/L glass fibre, containing a small amount of organic bond¬ ing agent reaction to fire: non-combustible according to norm IMO Res. A.472 (XII) nominal thickness-. 43 mm nominal density: 58 kg/m ³ ; measured 55.4 kg/m ³ specific heat: 840 J/kgK thermal conductivity: 0.035 W/mK bonding agent content: 6.83 w-% Reinforcing material manufacturer: IRS GmbH, Mannheim, Germany commercial designation: VAZOMAT reaction to fire: non-combustible according to norm IMO Res. A.472 (XII) (test report no. 5/530-649/94) Surface material manufacturer: IRS GmbH, Mannheim, Germany commercial designation: IRSOPAN reaction to fire: low spread of flame - Class 1 accord¬ ing to spread of flame test B.S 476, Part 7 (Test re- port no. 5/530-649/94-B) .

The test was performed according to norm IMO Res. A.754 (18) . The panel specimens for the test were placed in an upright position in an oil-heated oven so that they formed one wall of the oven interior, the heat being thus applied to one side of the panel. The temperature was measured at seven measuring points on the opposite side of the panel and the temperature

change was recorded as a function of time. Correspond¬ ing measurements were taken of the temperature inside the oven. The total duration of the test was 41 min. In Fig. 6 and 7, the temperature is shown in Kelvin de- grees on the vertical axis and the time in minutes on the horizontal axis. Fig. 6 shows the development of the oven temperature during the test, and, correspond¬ ingly, Fig. 7 depicts simultaneous development of the temperature at different measuring points on the outer surface of the panel during the test. Fig. 7 shows clearly that a cooling effect takes place in the struc¬ ture of the invention, keeping the temperature at a steady low level although the temperature in the oven rises all the time. It was established in the test that after 15 min from the start of the test, the average temperature rise on the outer surface of the test specimen was 59 °K. After 30 min, the average temperature rise on the outer surface of the test specimen was 66 °K, while the maximum increase was 85 °K at one point. The test showed that the specimen remained largely undamaged. The amount of distortion of the specimen away form the fire at 30 min was about 34 mm. In accordance with the test, the specimen was classified as "Class B-30 bulkhead" .

TEST EXAMPLE 4

A door assembly according to the invention, "IRSOPAN Door Class B15" was subjected to a fire resis- tance test according to norm IMO Res. A.754 (18) for class "B" door classification. (Test report no. 5/530-649/94-D, ZMRK-Institute for Research and Quality Control; Ljubljana, Slovenia) .

The door assembly, which measured 776x1976 mm, was fitted in the middle of a previously tested bulk¬ head "B-15". The door panel was made of rock wool sheet coated with polyester gelcoat, fibre glass mat, polyes-

ter resin, oxysulphatic bonding agent and aluminate bonding agent. The test was performed using an oven as in the preceding examples.

The sample material consisted of the following: Insulation: manufacturer: Termica, Novi Marof, Croatia commercial designation: TERVOL BSI 15 rock wool, containing a small amount of organic bonding agent reaction of fire: non-combustible according to norm IMO Res. A.472 (XII) nominal thickness: 33 mm nominal density: 150 kg/m ³ ; measured 159.9 kg/m ³ specific heat: 840 J/kgK thermal conductivity: 0.04 W/mK measured bonding agent content: 1.27 w-% Reinforcing material manufacturer: IRS GmbH, Mannheim, Germany commercial designation: VAZOMAT reaction to fire: non-combustible according to norm IMO Res. A.472 (XII) Surface material manufacturer: IRS GmbH, Mannheim, Germany commercial designation: IRSOPAN reaction to fire: Class 1 according to flame propaga¬ tion test B.S 476, Part 7 (Test report no. 5/530-649/94-B) .

The test was performed according to norm IMO Res. A.754 (18) . The total duration of the test was 33 min. In Fig. 8 and 9, the temperature is shown in Kel¬ vin degrees on the vertical axis and the time in min¬ utes on the horizontal axis. Fig. 8 shows the develop¬ ment of the oven temperature during the test, and, correspondingly, Fig. 9 depicts simultaneous develop- ment of the temperature at different measuring points on the outer surface of the door panel during the test . Fig. 9 shows clearly that a cooling effect takes place

in the structure of the invention, keeping the tempera¬ ture at a steady low level although the temperature in the oven rises all the time.

It was established in the test that after 15 min from the start of the test, the average temperature rise on the outer surface of the test specimen was 48 °K while the maximum increase was 166 °K at the door frame. After 30 min, the average temperature rise on the outer surface of the test specimen was 58 °K, while the maximum increase was 280 °K at the door frame. The test showed that the specimen remained largely undam¬ aged. At 25 min and 29 min, a piece of cotton was placed against the outer surface of the panel. The cotton did not catch fire. Maximum distortion of the door away from the fire was only 3 mm. In accordance with the test, the door was classified as "Class B-30 door" .

The invention is not restricted to the appli¬ cation examples presented above; instead, many modifi- cations are possible within the scope of the inventive idea as defined by the claims.