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(11) | EP 0 172 028 A2 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Fibre reinforced inorganic body |
| (57) To manufacture a fibre-reinforced inorganic body, a fibre body (7) comprising a plurality
of threads (13) is impregnated with a bonding agent (11) and is then embedded in an
inorganic composite (5). The inorganic composite (5) containing the fibre body (7)
is extruded, and the inorganic composite (5) and the bonding agent (11) of the resulting
extruded body are then hardened. |
[0002] Hitherto, there is known a process for manufacturing a fibre-reinforced inorganic body, as disclosed in Japanese Unexamined Patent Application Publication No. Sho 55-85480, in which a fibre body composed of threads is impregnated with an inorganic composite mainly composed of cement, that is the same in kind of material as an inorganic composite to be moulded by extrusion. The fibre body is then embedded in the inorganic composite to be moulded by extrusion, thereafter the inorganic composite including the fibre body is extruded, and thereafter the resulting extruded body is subjected to a hardening treatment.
[0003] The foregoing conventional process is, however inconvenient in that the bending strength of the fibre-reinforced inorganic body obtained thereby is not substantially improved as compared with that of a moulded inorganic body not reinforced with the fibre body.
[0004] This invention has for its purpose to provide a process which produces a fibre-reinforced inorganic body which is free from the foregoing inconvenience caused by the foregoing conventional process and which is improved in its bending strength. According to this invention, the process for manufacturing a fibre-reinforced inorganic body is characterized in that at least one fibre body comprising a plurality of threads is impregnated with a bonding agent and is embedded in an inorganic composite, the inorganic composite including the fibre body is extruded to be moulded, and the inorganic composite and the bonding agent of the resulting extruded body are hardened.
[0005] The present invention also provides a fibre-reinforced inorganic body comprising a moulded inorganic composite, at least one fibre body comprising a plurality of threads embedded in the moulded inorganic composite, and a hardened bonding agent included in the fibre body and forming a bond between the moulded inorganic composite and the fibre body.
[0006] Preferably, the inorganic composite is composed of cement, sand, and water and, if desired, may contain any other kind of inorganic material such as plaster. As for the cement there is preferably used Portland cement, aluminium cement, Portland blast-furnace cement, silica cement, flyash cement, etc. In the inorganic composite there may be optionally present any desired additive such as milling aids, retarders, accelerators, water reducing agents, coagulants, thickness, builders such as an air entraining agent, etc., and aggregate of a suitable size. Also in the inorganic composite, there may be mixed uniformly short fibres for improving the toughness of the fibre-reinforced inorganic body to be produced.
[0007] As for the short fibre, there may be used one or more of inorganic fibres such as carbon fibre, glass fibre, ceramic fibre, etc.; organic fibres such as aromatic polyamide fibre such as of straight coordinated aromatic polyamide, aromatic polyether amide, aromatic polysulphide amide, aromatic polysulphone amide, aromatic polymethylene amide, aromatic polyketone amide, aromatic polyamine amide and copolymers thereof, polyester fibre, polyolefin fibre, polyvinyl alcohol fibre, etc.; and metallic fibres such as cold drawn steel wire, steel wire for prestress, or the like. Such short fibres are in general several microns to several tens of microns in diameter and 5 to 15 mm in length. These are preferably mixed in the inorganic composite in an amount of up to 2% by volume relative to the inorganic composite.
[0008] The thread can be not only any type of yarn (preferably selected from roving, multifilaments, strand and sliver) but also a monofilament. Thus, more generally, the "thread" is an elongated flexible member.
[0009] The material of the thread is in general the same as that of the short fibre, but may be different therefrom.
[0010] The fibre body comprising the plurality of threads. (of the same kind or of two or more different kinds) is formed into a rod, sheet, tube or body of other desired shape.
[0011] The fibre body is formed by collecting the plurality of threads into a body of parallelly arranged, twisted or untwisted, threads. Alternatively, the fibre body is formed by interweaving the plurality of threads into a net, cloth or braid. The braided fibre body may be a cord which is round or square in section, a flat body or a body of other desired shape, for instance, so that the combined integrality of the individual threads thereof can be heightened. In this case, if the thread has protrusions in the longitudinal direction thereof, the frictional resistance between the threads of the braid becomes large, and consequently it becomes easy to transmit to the fibre body a stress applied to the threads, and at the same time the close contact between the fibre body and the inorganic composite is improved.
[0012] In general, there may be used the thread which is several microns to several tens of microns, and the amount of these threads in the inorganic composite is preferably up to 5% by volume relative to the inorganic composite.
[0013] In the inorganic composite, there may be embedded at least one fibre body, and in the case of the use of a plurality of fibre bodies it is preferable that they are so embedded therein as to be distributed uniformly.
[0014] As for the bonding agent, there may be used a coldsetting or thermosetting resin such as of epoxy type, polyester type, vinylester type, phenolic type, polyimide type, etc.; a coldsetting or thermosetting inorganic bonding agent such as of alkali metal silicate type, colloidal silica type, or phosphate type; or a mixture of a coldsetting or thermosetting organic resin and an inorganic bonding agent.
[0015] Embodiments of this invention will now be described with reference to the accompanying drawings in which:
Figure 1 is a diagram illustrating one embodiment of a process for manufacturing a fibre-reinforced inorganic body according to this invention;
Figure 2 is a perspective view of part of the body obtained by the embodiment of Figure 1;
Figure 3 is a diagram illustrating a second embodiment of a process for manufacturing a fibre-reinforced inorganic body according to this invention;
Figure 4 is an enlarged plan view of one embodiment of a braided fibre body used in the embodiment of Figure 3; and
Figure 5 is a perspective view of part of a fibre-reinforced inorganic body obtained by the embodiment of Figure 3.
Figure 1 is a diagram explaining one embodiment of a process for manufacturing a fibre-reinforced inorganic body according to this invention.
[0016] Referring to the drawing, there is shown a vacuum extruder 1 having an upper screw cylinder 3 and a lower screw cylinder 4 in communication with each other via a vacuum chamber 2. There is provided at one end portion of the upper screw cylinder 3 a hopper 6 for supplying an inorganic composite 5. One end of the lower screw cylinder 4 is in communication with a die 10 having a die opening 9 of a predetermined shape, via an adapter 8 for introducing a fibre body 7. The fibre body 7 is in the form of a rod, for instance, formed by collecting a plurality of roving type threads 13 of carbon fibre together in parallel and by then passing them through a dipping tank 12 containing a bonding agent 11.
[0017] In Figure 1, a single fibre body 7 only is shown for the sake of simplification, but actually in this case a plurality thereof is introduced into the adapter 8. Ahead of the die 10, there is provided a conveyer 14 for conveying extruded body 15. The body 15 is cut by a cutter 16 to pieces of a predetermined length, and the body 15 is transferred to the surface of a pallet 17. Referring to the drawing, numeral 18 denotes screws of each of the screw cylinder 3 and the screw cylinder 4. Numeral 19 denotes a supply source of the foregoing roving threads, and numeral 20 denotes a pair of driving rolls.
[0018] Now, one embodiment of the manufacture of a fibre-reinforced inorganic body, using the foregoing vacuum extruder 1, will be described. In the first place, an inorganic composite 5 composed of Portland cement, sand and water, for instance, is supplied to the hopper 6. The inorganic composite 5 thus supplied is introduced into the upper screw cylinder 3 and is moved forwards while being kneaded, and is then conveyed to the vacuum chamber 2 by the screw 18 of the upper screw cylinder 3, and is subjected, in that vacuum chamber 2, to a degassing treatment. Thereafter, the kneaded and degassed inorganic composite is moved forwards by the screw 18 of the lower screw cylinder 4 and introduced into the adapter 8. In the meanwhile, a plurality of the foregoing fibre bodies 7, impregnated with the bonding agent 11 of thermosetting resin by being passed through the dipping tank 13, are introduced into the adapter 8 and are embedded into the foregoing inorganic composite 5 so as to be disposed at predetermined positions therein.
[0019] Thus, the inorganic composite 5 having embedded therein the disposed fibre bodies is extruded through the opening 9 of the die 10 so as to be moulded into a desired shape, for instance, a hollow square shape as illustrated in Figure 2. The resulting extruded body 15 is then moved forwards by the conveyer 14 and is cut by the cutter 16 to pieces of a predetermined length in sequence. The body 15 is placed on the pallet 17 ahead of the conveyer 14, and is introduced into an autoclave (not shown). The extruded body 15 is heated in the autoclave so that the inorganic composite 5 and the bonding agent 11 inside and outside each of the fibre bodies 7 are both cured, and thus there is obtained a fibre-reinforced inorganic body.
[0020] Figure 3 is a diagram explaining another embodiment of a process for manufacturing a fibre-reinforced inorganic body according to this invention. This embodiment is different from the foregoing embodiment in that short fibres 21 are mixed in the inorganic composite 5 and that there is used as the fibre body a braided fibre body 7' formed by interweaving a plurality of strand-like threads 22 of total aromatic polyamide fibre and a plurality of braided fibre bodies, each supplied from a corresponding supply source 23.
[0021] In more detail, in the first place, an inorganic composite 5 composed of Portland cement, sand and water, mixed with the short fibres 21 of total aromatic polyamide, is supplied to the hopper 6. The supplied inorganic composite 5 is moved forwards, while being kneaded, in the upper screw cylinder 3 and is conveyed to the vacuum chamber 2. After being degassed in that chamber 2, it is moved forwards in the lower screw cylinder 4 and is then introduced into the adapter 8.
[0022] In the meanwhile, a plurality of the braided fibre bodies 7', each formed by interweaving the plurality of strands 22 of total aromatic polyamide, are passed through the dipping tank 12 containing a bonding agent 11 of thermosetting epoxy resin so as to be impregnated therewith, and are then introduced into the adapter 8 so as to be embedded at their predetermined disposed positions in the foregoing inorganic composite 5. Thereafter, the inorganic composite 5, which has the short fibres 21 dispersed therein and the disposed fibre bodies 7' embedded therein, is extruded through the opening 9 of the die 10, so as to be moulded into a desired shape, for instance, a hollow square shape as shown in Figure 5. The resulting extruded body 15 is moved forwards and is cut by the cutter 16 to pieces of a predetermined length in sequence. The bodies 15 thus cut are placed on the pallet 17 ahead of the conveyer 14 and are introduced into an autoclave (not shown). the bodies 15 are heated in the autoclave so that the inorganic composite 5 including the fibre bodies 7' and the bonding agent 11 existing inside and outside each of the fibre bodies 7' are both cured, and thus there is obtained a fibre-reinforced inorganic body.
[0023] In the foregoing two embodiments, the curing is carried out in the autoclave, but any other curing means such as steaming curing may be used. The bonding agent is not limited to a thermosetting one, since a coldsetting bonding agent may also be used.
Example 1
[0025] 36 strands, each made of total aromatic polyamide fibre ("Kevlar 49") of 1420 denier, were collected together in parallel to form a fibre body of about 3 mm in diameter, and the fibre body thus formed was impregnated with a bonding agent composed of 100 parts by weight of bisphenol A/epichlorohydrin type epoxy resin ("DER 332, Dow Chemical") and 14 parts by weight of triethylenetetramine in an impregnating ratio of 40 parts thereof to 100 parts of the foregoing fibre body. Eight fibre bodies, each thus impregnated with the bonding agent, were embedded in an inorganic composite comprising a mixture of 911 kg/m3 of Portland cement, 310 kg/m3 of water 1002 kg/m3 of sand and 13.67 kg/m3 of thickener, such that two lines of the four fibre bodies thereof were disposed above and below in the inorganic composite. The inorganic composite including such disposed fibre bodies was extruded under a vacuum of 75 mm Hg, under an extrusion pressure of 10 kg/cm2, and at an extruding speed of 1.5 m/minute, so that there was obtained an extruded body having a rectangular sectional shape of 50 mm by 100 mm. Thereafter the extruded body was cured for 14 days at 200C to produce a fibre-reinforced inorganic body. The bonding strength thereof was 176 kg/cm2.
Example 2.
[0026] A sectionally-round braided fibre body of about 3mm in diameter, formed by interweaving 36 strands each made of total aromatic polyamide fibre ("Kevlar 49") of 1420 denier, was impregnated with the same bonding agent as used in the foregoing Example 1 in the same impregnating ratio as used in the foregoing Example 1. Eight braided fibre bodies, each thus impregnated with the bonding agent, were embedded in an inorganic composite composed of a mixture of 911 mg/m3 of Portland cement, 310 kg/m3 of water, 962 kg/m3 of sand and 13.67 kg/m3 of thickener, and mixed with 1.5% by volume of short fibres ("Kevlar 49") each 1420 denier in diameter and 15 mm in length, such that two lines of the four fibre bodies thereof were disposed above and below in the inorganic composite. The inorganic composite including such disposed fibre bodies was extruded into a rod having a rectangular sectional form of 50 mm by 100 mm. Thereafter the extruded body was cured under the same conditions as those in Example 1 to produce a fibre-reinforced inorganic body. The bending strength of the body thus obtained was 215 kg/cm2.
Example 3
[0027] By using as an inorganic bonding agent lithium silicate in place of the organic bonding agent used in Example 1, a fibre-reinforced inorganic body was obtained in the same manner as in Example 1. The bending strength thereof was 90 kg/cm2.
[0028] For comparison, a fibre-reinforced inorganic body was obtained by using the same inorganic composite and the same fibre bodies embedded therein but without using a bonding agent in almost the same manner as in
Example 3.
[0029] For further comparison, a fibre-reinforced inorganic body comprising the same inorganic composite and the same fibre bodies embedded therein as those of the body of Example 3, but including no bonding agent, was obtained in almost the same manner as in Example 1.
[0031] Thus, according to this invention, after a fibre body comprising a plurality fo threads is impregnated with a bonding agent, the same is embedded in an inorganic composite, and the inorganic composite including the fibre body is extruded and the inorganic composite and the bonding agent of the resulting extruded mould are hardened, so that the inorganic composite and the fibre body are strongly bonded together through the bonding agent, and consequently there can be obtained easily a fibre body reinforced inorganic body which is improved in its bending strength.
1. A process for manufacturing a fibre-refin- forced inorganic body, characterized
in that at least one fibre body (7) comprising a plurality of threads (13) is impregnated
with a bonding agent (11) and is embedded in an inorganic composite (5), the inorganic
composite (5) including the fibre body (7) is extruded so as to be moulded, and the
inorganic composite (5) and the bonding agent (11) of the resulting extruded body
are hardened.
2. A process as claimed in claim 1, wherein the fibre body (7) is a braided body formed
by interweaving a plurality of threads (which are preferably large in tensile strength).
3. A process as claimed in claim 1 or 2, wherein the inorganic composite (5) contains
short fibres.
4. A fibre-reinforced inorganic body comprising a moulded inorganic composite (5),
at least one fibre body (7) comprising a plurality of threads (13) embedded in the
moulded inorganic composite (5), and a hardened bonding agent (11) included in the
fibre body (7) and forming a bond between the moulded inorganic composite (5) and
the fibre body (7).
5. A body as claimed in claim 4, wherein the fibre body (7) is a braided body formed
by interweaving a plurality of the threads.
6. A body as claimed in claim 4 or 5, wherein the moulded inorganic composite (5)
has short fibres dispersed therein.