AU646772B2 - Thermally-expansive heat insulating seal material - Google Patents

Description

P/00!011 Regulation 3.2 6?46772

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT o r Invention Title: THERMALLY-EXPANSIVE HEAT INSULATING SEAL MATERIAL The following statement is a full description of this invention, including the best method of performing it known to us: GH&CO REF: P21424-B:DAA:RK 1366 THERMALLY-EXPANSIVE HEAT INSULATING SEAL MATERIAL BACKGROUND OF THE INVENTION FIELD OF THE INVENTION: The present invention relates to a thermally-expansive heat insulating seal material having flexibility in which expansive graphite functions as an expansive material. It further relates to such a heat insulating seal material which can prevent flames from spreading and smoke from diffusing at the same time during a fire by forming a heat insulating seal layer in the gaps of a building, for example, in the gaps between a S door and a door frame, openings in walls (cable penetrating portions or ventilation holes) and between the inner and outer sides of walls.

DESCRIPTION OF THE RELATED ART: Conventionally, thermally-expansive materials used for the purpose of preventing fires are known such as a material mainly composed of alkali silicate (water glass), materials in which an organic foaming agent is added to a flame-retarded elastomer and materials mainly composed of expansive graphite.

For example, Japanese Patent Laid-Open No. 53-139400 discloses a flame retardant composite material used as a thermally-expansive material composed of alkali silicate. Such a thermally-expansive material emits steam under the action of heat, thereby foamily expanding and forming a heat shielding material. However, although the thermally-expansive material using -1A- V604.

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0 0 0 000 S alkali silicate starts to expand at a low temperature such as 150°C, it has a low expansion ratio of between 5 6 and also absorbs carbon dioxide in the air, thus reducing expansion performance. Moreover, it is foamily expanded so that it is friable, and consequently cannot resist mechanical stress.

Also, for example, Japanese Patent Laid-Open No. 1-174744 discloses an outer wall masonry joint structure used as a flame-retarded elastomer employing an organic foaming agent. However, although the flameretarded elastomer can have a high expansion ratio at The beginning of its expansion as a resent of the amount of foaming agent added, the foaming agent cannot stabilize such a high expansion ratio for a long period. In addition, when a large amount of an inorganic filler is added for improving flame retardancy, leakage of the blowing gas occurs, and thus satisfactory foaming cannot be obtained.

Further, for example, Japanese Patent Publication No. 58-12315 discloses a thermally-expansive filler using expansive graphite for the application of a joint or a gap or the like formed such that a composition containing 100 parts by weight of expansive graphite, from 10 to 30 parts by weight of polychromate butadiene, from 1 to 40 parts by weight of alkylphenol formaldehyde resin and from 1 to 3 parts by weight of a known stabilizer is coated on a base layer formed of glass or a synthetic resin fleece or a knit fabric used as a carrier. When an expansive graphite having such a composition disclosed in the publication as stated above is utilized, -2it has a high expansion ratio such as between 10 20, and expansion performance is also relatively retained even after lapse a long periods, although it starts to expand at a high temperature such as at approximately 200°C. However, the use of an excessive amount of expansive graphite makes such a filler friable and the foregoing mixture having a composition as described above cannot easily produce a material having good flexibility.

Furthermor, in general, the expanded graphite is easily scattered, and thus it is more difficult to retain its shape after expansion than a thermallyexpansive material using alkali silicate.

SUMMARY OF THE INVENTION Therefore, an aim of the present invention is to ameliorate at least some of the problems of the prior art.

It is an advantage that the present invention may provide a thermally-expansive heat insulating seal material which has good flexibility, a high expansion ratio and good retention of shape.

In one aspect of the present invention there is provided a thermally-expansive heat insulating seal containing from 45 to 60 percent by weight of inorganic fiber, from 5 to 10 percent by weight of aramid fiber, from to 20 percent by weight of rubber and from 10 to percent by weight of expansive graphite.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. I is a graph in which a broken line designates a conventional material and a full line designates a material 2 of the present invention -3showing the results of a differential thermal analysis of the conventional material and the material 2 of the present invention; Fig. 2 is a photograph showing a sectional view of an ordinary conventional material; Fig. 3 is a photograph showing a sectional view of a thermallytreated material of conventional material; Fig. 4 is a photograph showing a sectional view of an untreated material of the material according to the present invention; and Fig. 5 is a photograph showing a sectional view of a thermallytreated material according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION In a thermally-expansive heat insulating seal material of the present invention, when heat caused by a fire or the like is transferred to an expansive material, expansive graphite starts expanding at a temperature of approximately 200 0 C, which is the initial temperature of expansion, and 0 at the same time a binder, that is rubber, starts flowing. During expansion, expansive graphite expands explosively and is scattered with the rapid rise in temperature. However, this can be prevented by adding an aramid fiber sufficiently interlocked with rubber, so that the expansive graphite can be expanded. The aramid fiber also carbonizes without burning itself up in this process and contributes to the retention of shape. As the temperature further rises, an inorganic fiber forms a heat insulating seal layer when -4the binder (that is, rubber) and the expansive graphite are burned, and thus flames can be prevented from spreading.

The thermally-expansive heat ,nsulating seal material of the present invention contains from 45 to 60 percent by weight of inorganic fiber, from 5 to 10 percent by weight of aramid fiber, from 10 to 20 percent by weight of rubber and from 10 to 25 percent by weight of expansive graphite. As an inorganic fiber, artificial fibers such as glass fiber, rock wool and ceramic fiber, or natural mineral fibers, such as sepiolite and wollastonite can be used. It is not preferable to exceed or fall short of the ranges as mentioned above. If the mixing amount of an inorganic fiber is less than 45 percent by weight, it is difficult to retain the shape of 5 the heat insulating layer after the rubber, the aramid fiber and the expansive graphite are consumed by burning. On the other hand, if the lixing amount of an inorganic fiber is more than 60 percent by weight, flexibility is impaired when the seal material is formed in the shape of a .0 sheet or a rope.

o If the mixing amount of an aramid fiber is less than 5 percent by weight, flexibility cannot be obtained when the seal material is formed in the shape of a sheet or a rope and adequate interlocking characteristics with the rubber, the expansive graphite and the inorganic fiber cannot be obtained, either. On the other hand, if the additive amount is more than percent by weight, the aramid fibers tend to be interlocked with each other so that they overly inhibit expansion, thereby losing effectiveness.

in ^P As rubber, NBR, SBR, IR, acrylic rubber, silicon rubber, or the like, can be used. Or a latex of these rubbers can also be used. Less than percent by weight of the mixing amount of rubber cannot achieve sufficient binding effect. Conversely, if the mixing amount is more than percent by weight, it is difficult to retain the shape after the rubber is consumed by burning.

As expansive graphite, a naturally occuring scaly graphite having crystallizability that is provided expansibility by oxidation can be used.

In particular, such a graphite having a 10 60 mesh granule diameter is more preferable. In more detail of the expansive graphite is that in which sulfuric acid, nitric acid or the like is poured between the layers of natural scaly graphite to open them widely from the rapid heating. The graphite granules are thereby expanded between 100 300 times and present a S: honeycomb structure. Further, the expansive graphite may be produced by f i processing natural scaly graphite with concentrated sulfuric acid or nitric acid or the like, and a strong oxidizing agent, such as perchloric acid, a> perchlorate, bichromate and hydrogen peroxide. A compound is formed between *5 the graphite layers by pouring sulfuric acid or nitric acid or the like between the layers of the graphite, followed by washing and drying to thus produce expansive graphite. In general, the larger the granule diameter of the expansive graphite, the higher its the expansion ratio. Thus, expansive graphite having larger granule diameters can achieve the expansion effect more easily when used for thermally-expansive heat insulating seal material.

-6- Less than 10 percent by weight of the mixing amount of the expansive graphite is cannot achieve sufficient expansion effect. Conversely, if the mixing amount is more than 25 percent by weight, it is difficult for the material to retain its shape after the graphite has expanded. Thus, it is not preferable to exceed or fall short of the proper range as stated above.

Moreover, on top of the above components, an aging inhibitor for rubber or a flame retardant for rubber may be added to the thermallyexpansive heat insulating seal material according to the present invention.

As an aging inhibitor for rubber, an amine and ketone aging inhibitor (TMDQ), imidazoles (MBI, ZnMBI), phenols (DAHQ, DBHQ), or the like can be used, and the mixing amount thereof is in a range of from 0.5 to 3 percent above. Also, paraffin chloride or the like can be used as a flame retardant for rubber, and the mixing amount thereof is in a range of approximately from 3 to 7 percent by weight per totsl of the mixing amounts of the i components as described above excluding the aging inhibitor for rubber.

The thermally-expansive heat insulating seal material having such o a mixture ratio of the above components can be used in the form of a sheet or a rope. Such a seal material can be produced as follows. For instance, an inorganic fiber, an aramid fiber, expansive graphite, and the like are mixed by using a wet process with rubber cement or latex in which rubber is dissolved into an organic solvent, such as toluene, acetone and MEK. The resulting clay-like mixture is extruded into the shape of a sheet or a rope -7by an extrusion molding machine. Then, the organic solvent is removed by evaporation in a furnace. As a result, a flexible seal material in the shape of a sheet or a rope can be obtained. Alternatively, the foregoing clay-like mixture is formed into the shape of a sheet by using a roll forming machine followed by substantially in the substantially same way as stated above, to obtain a sheet. Or, the clay-like mixture may be formed and dried at the same time by using a thermal forming roller, to obtain the sheet.

EXAMPLE

*.999 Fiber materials (inorganic fibers and an aramid fiber), expansive .9 graphite, rubber cement (NBR) which was prepared by being dissolved in toluene, and an aging inhibitor as shown in Table 1 were mixed and stirred by employing a kneading-type stirrer, the thereby prepare a clay-like mixture. After the resulting clay-like mixture was extruded into the shape of a sheet (2mm) by using an extrusion forming machine, a solvent in the sheet was scattered and dried in an air heating furnace. The resulting sheet was provided as a sample. Various characteristics of the materials of the 9 present invention obtained as described above, comparative materials and a conventional material are indicated in Table 1.

The conventional sheet was prepared by the following process. A mixture having substantially the equivalent weight of a mixing ratio to that of the conventional sheet in Table 1, which uses toluene as a solvent, was coated with a glass fiber fleece at 50g/M 2 as a carrier and, then dried, -8to thus form a sheet-shaped material.

Table 1 Comparative materials Material 1 2 Rock wool fiber 6 2 Sepiolite 28 11 Asbestos fiber Aramid fiber 3 NBR 16 17 Materials of the present invention 1 2 12 10 1 54 46 4 5 7 13 18 1 (wt Conventional material a.

U *909 a. a *c a a. a CR Phenol resin Aluminium hydroxide Expansive graphite 50 67 Stabilizer Paraffin chloride (outer percentage) 6 19 19 a Aging inhibitor 3 3 2 2 2 (Diazo-compound)(outer percentage) Expansion ratio 28 26 13 18 18 (350°C/5 minutes) Retention of shape X A 0 0 0 0 (350°C/5 minutes) Retention of shape X X 0 0 0 X (up to 1000°C) Flexibility A A A O 0 x Decision criteria X: Impossible to and broken.

retain shape, bent at flexibility value -9- A: Retained shape.but impossible to handle it, bent at flexibility value 10mmck and cracks occurred.

0: Good retention of shape, no cracks occurred when bent at flexibility value Very good retention of shape, no cracks occurred when bent at flexibility value 8mm Differential thermal analysis was perinrmed on 4.3mg of both the seal material 2 of the present invention and the conventional seal material obtained as stated above. The result is shown in Fig. 1.

As will be understood from the results shown in Fig. 1, an organic binder in conventional seal material is consumed by burning at a temperature of up to 480"C, whereas the aramid fiber functions as a substitute for a binder in the seal material 2 of the present invention and retains the shape of the material. Figs. 2 5 are photographs showing sectional views of ordinary materials of the material 2 according to the present invention and the conventional material and materials thereof which are heated at a temperature of 1000°C. As will be clearly seen from Fig. 5, it is confirmed 0000 that even a material which is t-eated thermally at a temperature of 1000GC in the seal material 2 of the present invention forms a firm seal layer without collapsing the expansive layer formed by the inorganic fiber.

Consequently, the present invention offers the following advantages.

The thermally-expansive heat insulating seal material of the present invention contains from 45 to 60 percent by weight of inorganic fiber, from 5 to 10 percent by weight of aramid fiber, from 10 to 20 percent by weight of rubber and from from 10 to 25 percent by weight of expansive graphite and the expansive graphite functions as an expansive material in the flexibile seal material. A heat insulating seal layer is formed in the gaps of buildings, for example, in the gaps between doors and door frames, opening in walls (cable penetrating portions or ventilation holes) and between the inner and outer sides of walls, thereby in the case of a fire, preventing at the same time fire flames from spreading and smoke from diffusing.

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Claims (5)

1. A thermally-expansive heat insulating seal material containing from 45 to 60 percent by weight of inorganic fiber, from 5 to 10 percent by weight of aramid fiber, from 10 to 20 percent by weight of rubber and from to 25 percent by weight of expansive graphite.

2. The thermally-expansive heat insulating seal material according to Claim 1, wherein said inorganic fiber is a man-made fiber and/or a natural mineral fiber.

3. The thermally-expansive heat insulating seal material according to S Claim 2, wherein said man-made fiber is one or more selected from the group consisting of glass fiber, rock wool and ceramic fiber.

4. The thermally-expansive heat insulating seal material according to

9. Claim 2, wherein said natural mineral fiber is sepiolite and/or S wollastonite. I S*9 The thermally-expansive heat insulating seal material according to Claim 1, wherein said rubber is selected from the group consisting of NBR, *a SBR, IR, acrylic rubber, silicon rubber, and a latex of ths3e rubbers. 6. The thermally-expansive heat insulating seal material according to Claim 1, wherein said expansive graphite is obtained by oxidizing crystallizable naturally-obtained scaly graphite and providing thermal expansibility for said scaly graphite. -12- S. S S5 S S S S 0* *D S 7. A thermally-expansive heat insulating seal material substantially as herein described with reference to any one of figures 1, 4 or 5 of the accompanying drawings, or Example 1, or Table 1, excluding com .rative and conventional materials. Dated this 15th day of April 1993 ASK CORPORATION By their Patent Attorney GRIFFITH HACK CO. 9 4 -13- ABSTRACT OF THE DISCLOSURE An object of the 'present invention i to provide a thermally- expansive heat insulating seal material which has good flexibility, a high expansion ratio and good shape retention. The thermally-expansive heat insulating seal of the present invention contains from 45 to 60 percent by weight of inorganic fiber, from to 10 percent by weight of aramid fiber, from 10 to 20 percent by weight of rubber and from 10 to 25 percent by weight of expansive graphite. .9 *ace S oo* se. f *4 S S