CA1109084A - Process for manufacturing inorganic heat insulating material - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A process for manufacturing inorganic heat insulating material by mixing a water-soluble alkali silicate, preferably a water soluble alkali metal silicate, alumina cement, a metal base foaming agent and a foam stabilizing agent into pasty state in the presence of water. The heat insulating material manufactured by this process is of the class useful for heat insulating walls of buildings and for heat insulating plates incorporated in machinery.

Description

11~)9CP84 lrhis invention relates to a ~rocess for manufacturing an inorganic hea-t insulating material~ more particularly to a useful process for stably yielding! in a short period of time, an inorganic heat insulating material containing uniform foams, which foams and hardens simply by mixing up the ingredients into pasty state, even without any heating operation.
There have been various proposals for obtaining inorganic foam materials based upon aqueous solution of alkali silicates. Among such processes there are, for example, a process for foaming the solution by directly heating same, a process of first mixing with the solution a foaming agent which will generate a gas upon heatina and then gelling the mixture followed ultimately by foamin~ up the ael by heating same, and a process of first mixing with the solution a hardening agent, such for instance as silicofluoride followed by heating the mixture thus formed to hardening and foamlng same. All such processes essentially require heating (normally in the range of 200 - 900C) to obtain the foamed material. Namely, the alkali silicates and the foaming agents never cause a foaming reaction at normal temperaturesj and heating is indispensable for the foaming. It is also to be noted that the foamed product obtained by such processes contains water~soluble alkali components which will easily dissolve out upon contact with water thus markedly impairins the structural strength of the foamed product, which has, therefore a ver~ narrow scope of use as a heat insulating material, because of such low resistance to natural water.
In the fields of concrete and mortar, inorganic lightweight materials highly resistant to water and with high mechanical strength are known, for instance as lightweight concrete and lightweight mortar, but most of them are made simply by incorporating suitable lighweight aggregate such as perlite, and vermiculite. It is also known to mix metallic aluminium and water with cement, to knc~d the mixtllre and to submit the mixture under heat and pressure in an autoclave~ thus causing an exo-thermic hydraulic reaction with simultaneous foaming by hydrogen gas generation. This process, however, requires troublesome operations as curing in the autoclave, and the time required for the foaming and hardening is very long, particuarly the hardening normally requiring as long as one week or so. It should further be noted that -the various processes as mentioned above can not produce a foamed product of sufficiently lightweight, the best lighweight product having a density of more than 0.5.
The present invention provides a process for manufacturing a useful inorganic heat insulating foamed material which eliminates all the drawbacks of the conventional processes for manufacturing such material.
According to the present lnven~ion there is provided a process for manufacturing the inorganic heat insulating material which comprises mixing into a pasty state, in presence of water, the ingredients comprising: (A) water-soluble alkali silicate (hereinafter referred to as ingredient A); (B) alumina cement (hereinafter referred to as ingredient B); (C) metal base foaming agent (hereinafter referred to as ingredient C); and (D) foam stabilizing agent (hereinafter referred to as ingredient D).
One of the most important features of this invention is to readily yield the desired heat insulating material at normal temperature and normal pressure simply by mixing the said ingredients A - D into a pasty state, without the necessity of heating subsequent to the mixing. The foaming reaction of the mixture requires only short period of time, normally in t'ne range of 5 - 60 minutes, which is defined ~lmost definitely by the composition of the mixture, and subsequent hardening proceeds also rapidly, normally to complete within 24 hours. Furthermore, use of the mixture in pasty state allows the use of a casing mould or frarne o~ a]rnost any complicated shape without causing difficulties, thus readily allowing the formation of the desired product in any design. The foaming pressure of the paste is relatively low, which permits the use of even corrugated paper board for the casting wall, thus reauiring no specific casting frame of substantial strength, and the paste can be poured into the desired place to be hea-t insulated, simply with proper confine- -ment walls. The pastv mixture according to this invention is further characterized by the excellent stability of the foaming reaction which is little influenced by the ambient conditions such as the climate. It provides the possibility of regulating the foaming reaction time, by properly regulating in the composition the ratio of the said ingredients A D, which may thus be set and then kept almost uniform and constant to the desired value within the said possible range, and also of easily regulating the foaming overrun ratio and thus the bulk density of the product. With respect to the bulk density, in particular, an extremely low density can thus be provided, such as in the range of about 0.1 - 0.3 g/cm3 which has never been possible with the conventional autoclaved lightweight concrete, generally called ALC and known to have excellent mechanical stren~th. The product of such low density still having sufficient mechanical strength for practical use as the heat insulating material There is no difficulty in manufacturing the product with similar bulk density and similar mechanical strength just as the said ALC, and such product may now be half the low heat conductivity coefficient as compared with the ALC.
The inorganic heat insulating material provided by the process of this invention has the foams of substantially uniform diameters~ in the range of 0.5 - lO mm as the case may be, and the foam structure is very robust. This material thus has excellent heat insulation, noncombustibility, resistance to heat, and 9~4 interception of fire flame, Especially, the heat resistance is excellent as is proved by the test of keeping the samples in a 700C furnace for 24 hours, causing no appreciable deformation of the samples. Still more, this material according to this invention has a very excellent resistance -to water, acid and alkali, as well as mechanical strength, as are not achieved by the conventional foamed alkali silicate material.
The reason why the inorganic heat-insulating material with the properties as mentioned above can be manufactured according to the process of this invention simply by mixing the said ingredients A - D is not very clear as at this time, but it may perhaps be as follows: Upon mixing into the paste, most of the ingredient B, namely the alumina cement (or the same together withportlandcement), reacts with water to gradually be hardened as a hydraulic reaction, while a part of the ingredient A, namely the water-soluble alkali silicate, as well as part of the said ingredient B, undergoes hydrolysis in the paste to give rise alkaline agents, such as alkali metal hydroxides, and the groups, such as SiO3 and AlO2 . Said alkaline agents then coact with the ingredient C, namely metal base foaming agent, to promote the foaming action for generating the minute foams within the paste or the hardening ingredient B, and said groups, such as SiO32 , gradually undergoing gellation in parallel with said foaming reaction, so as to be intimately packed in the mass of the hardened ingredient B. This results according to this assumption, in improved mechanical strength, of the solid foamed product. As for the ingredient D, namely the foam stabilizing agent, it is assumed that while the hydraulic reaction of the ingredient B and the foaming reaction between the ingredients A/C and B/C proceed, it keeps the dispersion of the ingredient C uniform within the entire bulk in spite of an inclination to do otherwise, thus ensuring its function for ~9G11~4 stabilizing the foaming ~eac~;.on and preventing locali.zation as well as serial continuation of the minute foams as generated.
In any case, the process of the present invention readily enables the stable manufacture of the inorganic heat insulating material with excellent characteristics, simply by uniformly mixing the ingredients at normal temperature and normal pressure, which is of great industrial value.
In the process of this invention, it is essential to use a water-soluble alkali silicate as the ingredient A, preferably an alkali metal silicate, thus yielding the inorganic heat insulating material as expected. Such heat insulating material can not be made from insoluble or sparingly or difficulty water~soluble alkali silicate, such as the common anhydride liuid glass cullet As alkali metal to constitute this ingredient A, various examples may be mentioned such as Li, Na, K and Rb. Na and I~ are preferable since such are available quite economically and yet greatly promote the foaming function.
So long as it is water-soluble, the ingredient A puts no specific limitation as to the composition and the mol ratio between the metal oxide (represented as RI2O) and the SiO2. :
A preferable range-of the mol ratio Sio2/RI2o lies generally from 1.5 - 4.0, with the most preferable range being from 1.8 -3.0, Such ranges will yield a heat insulating material especially good both in resistance to water and in mechanical strength. One ingredient A or two or more ingredients A may advantageously be used either in the form of powder or in the form of aqueous solution, but in view of convenience in preparing the paste, it is preferable to use same in the form of aqueous solution with a solids concentration of 20% or more, and usually in the range of about 20 60%. Thus, when the ingredient A is used in the form of aqueous solution of the concentration in such a range, the paste with proper flowability ~1~9~4 can then be easily prepared si~ply by admixing same with the other ingredients B , D, and the shrinkage coefficient for the hardening can be comparatively moderate.
The ingredient B is, as already mentioned, alumina cement which is a hydraulic cement containing CaO and A12O3 as the main components thereof, and any commercially available alumina cement with various composition ratios may be used as ingredient B in the present invention The calcium aluminate component of the alumina cement may take the various forms such for instance as tri calcium aluminate (3CaO.A12O3), calcium aluminate (CaO.A12O3), calcium di-aluminate (CaO.2A12O3) and calcium hexa-aluminate (CaO.6~12O3), and any one of them as shown in such composition can advantageously be used in this invention for achieving the effect desired, which can however not be attained with cement material other than alumina cement.
A particularly preferable composition for the alumina cement is in the range of CaO in 36 ~ 59% and A12O3 in 39 ~ 53~, with possibility of some harmless lmpurities as Fe2O3 in the range 1 ~ 16% and SiO2 in the range 3 ~ 9%. Any one of the alumina cements may be used alone or two or more may also be used.
It is preferable to use same in a powdery form normally of a size under 100 microns mesh. In this invention, it is also possible to add a certain amount of portland cement to the said alumina cement, as the ingredient B. By portland cement it is meant the normal type of cement containing calcium silicate as the main hydraulic component, and in the trade there are classifications of those commercially available such for instance as normal portland cement, rapid hardening portland cement, ultra rapid hardening portland cement and moderate heat portland cement, with some differences in the composition therebetween, and any portland cement may be used in this invention. The use of such portland cement, of one or two or more types, in a powdery form ~r 6 ~39~4 under about 100 microns in si7.e~ in combination with -the said alumina cement, has the effect of shortening the time required for hardening the paste of this invention. However, too much will make the hardening too short and is apt to cause difficulty in obtaining good foaming. It is therefore preferahle to use the portland cement in a solids weight ratio of under 30 parts to 100 parts of alumina cement. A most preferable range is under 20 parts, since such will yield the heat insulating material having especially good resistance to water.
As the ingredient C of this invention, it is possible to use various metal elements and metal alloys or intermetallic compounds. As the metal element, any member belonging to groups I B, II A, II B, III A, III B, I'V A, I~l B, ~1 A, ~I B, VII B and VIII in the Periodic Table may be used, of which the elements belonging to the 3rd to 5th groups are preferable. Suitable metal elements may be mentioned by way of example include Mg, Ca, Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Ga, Sn, and Sb, of which the most preferable are Al, Mg, Fe, Ni, and Zn, because of easy availability and good reactivity. In the process of this invention, semi-metallic elements such as B and Si may also be used just like the metallic elements mentioned above. Furthermore, alloys of the said metals or intermetallic compounds (i.e.
compounds with chemical bonds in between metals or between metal and nonmetal) may also be used in this invention just as the said metals. By way of example, typical alloys or the intermetallic compounds may include Al-Si, Al-Ti, Al Mn, Al-Cu-Si, Al~CU, Zn-S, Zn Sn, Sn-Fe, Cu-Sn, Su-Si, Cu-Pb, Cu-Ni, Fe-Ni, Fe-Mn, ~e~Cr, Fe-Si, Mn-P, Si~Ni, Co-Sb and Mn-Ag. It is preferable to use the ingredient C, either of one or two or more types, normally in a powdery form, especially of under 150 micron size.
As the ingredient D of this invention, namely the foam i9~34 stabilizing agent, it is possible to use an inorganic substance selected from silica gel, zeolite, artificial zeolite, carbon black, active carbon, alumina gel, talc and mica, or an organic substance such as animal protein which is conventionally known as a foaming agent for cement bulk, dimethyl silicone derivati~es and the like. The ingredient D has the function of keeping the dispersion of the inyredient C uniform within the entire bulk and stabilizing the foamina reaction, and is -thus effective for generating minute, uniform foams. If the ingredient D is an inorganic substance, it is preferable to use same in a powdery form normally of a size under 200 microns mesh. The composition ratios of the ingredients A - D
may vary in accordance with what kind of substances compose each of the ingredients, concentration of the ingredient A when in particular the same is used in form of the a~ueous solution, bulk density and strength of the product as desired, and casting conditions for forming the desired product. Generally, however, taking the solid portion of the ingredient A as the basis, thus to 100 parts in weight thereof, the ingredient B may have the solid portion in the range of about 100 - 700 parts by weight, preferably 140 - 500 parts by weight, and the ingredient C may be in the range of about 0.5 ~ 35 parts by weight. As for the ingredient D, it may have the solid portion in the range of about 5 - 50 parts by weight if it is an inorganic substance, or about 0.1 - 3 parts b~v weight if organic. Generally speaking, presence of an excess of the ingredient A tends to cause unstability of the foaming and of the bulk density, thus to yield the product heat insulating material with uneven foam dispersion and low resistance to water. Too much of the ingredient B tends to cause a too high paste viscosity in the paste preparation, thus lowering its workability. As for the ingredient C, too small an amount thereof will cause insufficient foaming thus to result in a heavy bulk density (about 1,0 specific gravity or more)~ while too great an amount thereof will cause excessive foa~ing in large bubbles within the product which is thus difficult to have the strength as desired As for the ingredient D, assuming first the same is an inorganic substance, too small an amount thereof will cause uneven foaming, while too great an amount thereof will make paste preparation difficult. When it is an organic substance, too much of such will cause serially continuous foams thus resulting in a low heat insulating effect.
In the process of the present invention, the ingredients A ~ D are mixed in the presence of water into a pasty state, as mentioned already. No particular limitation is put to the method of the mixing, and it ls possible to simply mix the ingredients A - D together with proper amount of water all at once, It is advantageous, for ease of operation, to first mix in the predetermined ratios the ingredients B - D each being in a solid powdery state, and thereafter to admix such mixture with the in~redient A which is in the form of aqueous solution. As the ingredients B and C will start hardening and foaming reactions in a very short period of time after the mixing, these two ingredients are preferably added simultaneously to form the paste. In the preparation of the paste by mixing the ingredients A - D, it is preferable to use the amount of water as will ultimately result in that the ingredient A and total water in the paste is that which would make an a~ueous solution of the ingredient A having a concentration within the range of 20 - 60%, preferably 20 - 50~, based on such total solution weight, should these two have been mixed alone. It is also preferable to make up the paste normally with agitation or the like so as to have the solid particles dispersed unlformly.
At all events, it is essential in this invention to mix the ingredients A - D into pasty state in the presence of water, _g_ ~9~4 since no su~ficient foamed and hardened material will be obtained without such a pasty state. It is to be understood that "paste" as so far referred to means a soft, viscous dispersion of solid particles, with the viscosity of the paste in the process of the invention being normally in the range of about 0.5 - 300 P at 25C.
To the paste as prepared as above, it is possible to add, when needed, lightweight aggregate powder usually kilned at a temperature over 1000C, such as foam silica, perlite, vermiculite, SHIRASU-balloon (i.e. volcanic soil mainly in Kyushu, southern ]sland of Japan, Kilned to form balloon-like particles), for further lowering the bulk denslty of the product. Further, it is also possible to add, for the purpose of filling and increasing the volume and/or of reinforcement, various conventional fillers such as gypsum, fused quartz, sintered cristobalite, silica powder, fly ash and alumina powder. Care must however then be paid as to the type and volume of such fillers so that proper reaction of the said essential ingredients A - D should not be affected. Further if gypsum is chosen, it has the function for stabilizing the foaming reaction in addition to filling and increasing effects.
According to this invention, both the hardening and foaming reactions concurrently start immediately after the paste is prepared by mixing the ingredients A - D and, when needed, the lightweight aggregate powder or the like as well. Such concurrent reactions of hardening and foaming proceed quite well at normal temperatures and normal pressures even without any external heating, normally over about 5 - 60 minutes, and the hardening reaction will be completed within 24 hours. The avoidance of the need of heating and pressure in the process of this invention as mentioned above is from an industrial view point quite advantageous It should however be noted that the 9~

foaming and harden;ny reactions proceed at -the tempcrature in the range of about 5 - 90C. It is possible to effect heating up to about 90DC, where promotion of the reaction is desired. For usual applications, a temperature range from the ambient temperature to about 50C is preferred.
In such manner, an inorganic heat insulating material is obtained according to -this invention, which contains uniform foams, of a size usually in the range of 0 5 - 10 mm diameter and which is of low specific gravity and of high strength and is excellent with respect to water absorption coefficient, freezing and thawing stability, resistance to water, resistance to chemicals, heat insulation, heat resistance and resistance to flames.
As the inorganic heat insulating material according to this invention has the various characteristics as mentioned heretofore, it may induce further advantages according to what the use may be. Some special examples of use are as follows:
Central heating systems have been widely spreading in recent years as heating means for the residential houses, hotels, and hospitals. There~ the heat source is hot water and duct pipes for the hot water are installed within the floors and walls and occasionally in the ceilings as well. Conventionally a thermal conductor plate such as aluminium foil is put on the inner room side surface of such wall containing the hot water pipe and an exterior metal plate is put on the outer side of the building, with hard polyurethane foam poured therebetween as packing and heat insulating material. However, the polyurethane foam, being an organic substance, it not resistant to overheating and high temperature steam, and has in addition the vital defect of flashing up or scorching in smoke when attacked by flames in case of fire. It is also the drawback that curing or aging in irregular deformation ~s a~t to develop internally at the boundaries with the said thermal conductor plate and the ~9~84 ex~erior metal plate, thus often causing to dew water to collect there.
Using the inor~anic heat insulating material according to this invention instead of such conventional hard polyurethane foam, its excellent resistance to fire, heat and flame will reduce the fire hazard, should such occur, and the heat insulation effect itself is higher than with the polyurethane foam.
Furthermore, it has good bonding characteristic to the thermal conductor plate and the metal plate, thus providing good absorption to shock, and high working efficiency is attained bv the simple operation of pouring the paste.
As is evident, similar advantages are likewise present in the use of the heat insulating material of the present invention for heat insulating walls not included in such central heating system. Walls of the buildings in general, with exception of the use of concrete structure, often contain hollow spaces in their structure, as is quite common in view both of reducing the costs for the reinforcement steel skeletons as well as pre-fabricated structures and PC wires, and of enhancing the heat insulation. ~t is now possible to form up heat insulating walls by pouring the paste, forming the heat insulating material according to this invention, into the said hollow space. The inventors have performed various experiments with this respect, and have got there quite unexpected findings. In such experiments a pneumatic feed pouring system is used as means of supplying the heat insulating material of this invention to the wall structure, thus pouring same into the hollow space within the wall throug~ an aperture of proper size. This results in a uni-form foam mass even when poured lnto a hollow space with a slit of about 50 mm wide, with a quite excellent l'rising-up property", i,e.~ the property of the oaming heat insulating material to heap up vertically w~th increasing bulk volume during the foaming step, ~ 9~ ~ 4 which bulk volume ovcrrun ratio and ~he risin~ up ratio bein~
thus desired to be identical especially when the bottom area is conEined to remain constant, and which reveals that such excellent risina up property is more prominent as the paste is poured more promptly after being mixed. Generally speaking, the width of the slit in the hollow space in the building walls ranges from about 30 mm when narrow, to 200 or 300 mm when wide and usually in the range of abou-t 50 - 100 mm. The height when modularized, is under 5 m at the most in view of the structural restriction, while width of the hollow space is less than 2 m. Assuming now a hollow wall with sl;t width 100 mm, hollow space width 1 m and height 3 m, such is just an example of "casting plates with hollow space therebetween".
It has so far been considered to be quite difficult in the prior art to attain the 3 m rising up by pouring the conventional plastic foam, and the foaming reaction then results in f~ams lacking uniformity, thus with a poor heat insulating effect.
In such instance, however, pouring the paste of this invention by means of a pneumatic supply system immediately after mixing thereof has given adequate results in view both of the rising up property and uniformity of the foams. It is possible, therefore, to easily form walls having excellent heat insulation, shock absorption and resistance to water, not only in the buildings under construction but also ln the existing buildings, simply by pouring the paste of this invention through an aperture as may be drilled in the top portion of the part in question. Such building structure with hollow spaces may be of various materials such as concrete, mortar, asbestos cement board, and wooden fiber cement board, and in the possihle case of metal plate or plastics plate~ i.e " the material with poor bonding propert~ there will eyen then be no serious hinderance against the formation of a heat insulating wall according to this invention, 93~4 when paper is pre-applied on the working surface.
Amon~ the various adv~nta~es over the foam ~lastics conventionally used for heat insulating walls, the yood bonding property should not be i~nored. Mak~n~ use of the good bonding action, it is possible to simply and easily perform tiling work.
It is conventional to form heat insulating tile walls by affixing tiles onto foa~ plastics surface thus to make use of the heat insulatina function of the foam plastics. I-lowever, the foam plastics have rather poor bonding properties themselves, and thus require a good amount of adhesives. If the heat insulating material of this invention is used instead of such foam plastics for bonding tiles thereon, the working efficiency will then be improved without the use of adhesives, and also the additional effect of attaining excellent resistance to fire and shock, as can never be expected with the foam plastics, may simultaneously be achieved.
The present inventiQn will be further illustrated by way of the following Examples, in which the ingredients A-D
are selected from those as listed in Tables 1 - 4:

Table 1: Ingredient A
No. Sul)stance Mol ratio ~ncentra- ~emarks _ SiO2/R120 tion (%) _ A- 1 aqueol-s solution 2, 0 20 Made by Osaka of sodium solution Keisan ~oda A-2 aqueol~.q solution 3.0 30 di.to of potassium ,sol A-3 aqueou~ solution of 2.2 50 Reagent lit~ium silicate ___ A-4 ~owder natrium 3.2 80 A-l dried and 3 0 silicate Icr~ me sh .

~ 14 Tal>le 2: Ingredicnt B
~o . Articie M ol ratio ~ e ~h ~e1narks 12 3/ 1 2 (mlcron) B-1 *DENKA l~lgh 1.57 5 - 100 Made by Alumina Cement The Electoro-Chcmical , Industrial Co., Ltd.
B-2 DENKA High 0.85 5 - 100 ditto ~lumina Cernent 11 .
_ _ _ .
B-3 *ASAHI Alumina o.78 5 - 100 Made by Cement I Asahi Glass Company, Ltd.
* trademarks Table 3 ~ Ingredlent C
No. ~1ctal (s) Mesh Remarka (micron) C-l Sl 1 - 50 Reagent Extrcl Grade C - 2 1 - 100 ditto . . . .._ C-3 Al 1 - 50 Powder for Paint, m&de by Toyo Alumlnium K . K .
C-4 Al-Cu 5 - 100 Rea~ent Extra Grade C-5 Fe-Sl 5- 100 ditto .

, Table 4: Ingredlent D

.. .
No. Substance Mesh . Remark.
( Arffcle ) (micr~) D-l active carbon 5 - 50 Made by Taihei Chemical Industrial Corporation, Ltd.
D- 2 zeolite 10 - 100 Mined in N orth - Eastern region , . of Japan . ._.
D-3 talc 10 -150 Mined in Tajima re~
Hyogo-~refecture, Japan D-4 mica 20 - 200 Mined in North- Eastern region of Japan . . . _ . .
D-5 *"Glufoam" ________ Animal protein for cement foamino, made by Sun-Orient Chemical Co. , _ Ltd .

* trademark 1~09(~4 The properties of the inor~anic heat insulating materials obtained by the experiments were tested and measured in accordance with the methods as follows, with the ambient testing condition uniformly maintained in 20+ 2~C and 65 + 10%
relative humidity;
a) Bulk density: in accordance with JI5 (Japanese Industrial Standard) A-1161 b) Water absorption coefficient; Shown in ~ weight ratio, in accordance with JIS A-1161 c) Compression strength Shown in Kg/cm2, in accordance with JIS A-1161 d) Resistance to water: Judging outer appearance of the samples after soaking in water for 10 days, marked "-~' if no change and 11+~1 if any e) Resistance to acid: Judging outer appearance of the samples after soaking in l N HCl for 2 days, marked 11_~ if no change and ~1+~1 if any f) Resistance to alkali: Judaed as to any change or not in outer appearance after soaking in saturated Ca(OH)2 solution for 2 days g) Thermal conductivity: Shown in kcal/m.hr.~C, in accordance with JIS R-2616 h) Foam size: Shown in mm diameter, as measured with the foams appearing on cut surfaces of the samples i) Resistance to heat; 3udging deformation of the samples after keepin~ in 650~C furnace for 24 hours, marked 11~1~ if any deformation and 1l_ll if no and ~ j) Resistance to flame: 3udging deformation of the samples~ after directly exposing to flame for 10 seconds~ marked 1~+1~ any deformation and ~ 1 if no.

~o~ 4 Example 1 As the ingredient A, 100 grams of the aaueous solution A-l were put in a polyethylene container (1.5 liter). A mixed powder was prepared by mixing 100 grams of B-l, 5 grams of C-l and 7 grams of D-l, as the ingredients B, C and D, respectively.
A uniform paste was then made by adding -the mixed powder to the polyethylene container having the ingredient A and admixing same by agitation at ambient temperature. The paste, subsequently in the container, gradually started foaming and the foaming was complete in about 50 minutes. Foaming occurred to an extent to overflow the brim of the polyethylene container. The inorganic heat insulating material 1 according to this invention was obtained by letting same stand thereafter for one entire day thus completing the hardening. Shown in Table 5 are the results of the time (in minutes) required for the foaming for thusly obtaining the heat insulating material and of the properties thereof as measured.
Examples 2 and 3 Inorganic heat insulating materials 2 and 3 were made similarly as in Example l, with the only exception of changing the ingredient A from A-l to A=2 and A-3, respectively. Shown also in Table 5 are the foaming time and the properties of the respective heat insulating materials as so provided~ ;~
Example 4 A mixed powder was provided by putting 50 grams of powder A-4 as the ingredient A, lO0 grams of B-l as the ingredient B, 5 arams of C-l as the ingredient C and 7 grams of D-l as the ingredient D, into a polyethylene container and admixing same.
~ To the mixed powder 50 grams of water were then added and made Into unifor~ paste by admixing with agitation at ambient temperature, The paste, subsequently maintained in the container, ~radually started foaming and the foaming was complete in about 15 minutes after mixi,ng and agitation with water. Foaming occurred to extent to overflow t,he brim of the polyethylene container.
Inorganic heat insulating material 4 according to this invention was obtained by letting same stand thereafter for one entire day thus completing the hardeninat Shown also in Table 5 are the foaming time and the properties of the heat insulating material as so provided.

Table 5 ' 10 Example (heatinsulatin8 mat~rial) No.
Fo~ing time (minutes) 50 45 5 48 (a) 0. 32 0 . 29 0 . 35 0 . 31 (b) 0.2 0.3 0.3 0.2 ~c) ¦ 5-0 ¦ S- ~ ~ 5.1 ¦ 5 .
P roperti~s (f) : (g) 0.07 0.07 0.08 0.07 :~ ~ 12-4 Examples 5 to 8 Inorganic heat insulating materials 5 and 6 were provided similarly as in Example 1, with the only exception of changing the ingredient B from B-l to B-2 and B-3, respectively.
Likewise, inorganic heat insulating materials 7 and 8 were provided again similarly as in Example 1, with the only exception of modi~ying the ingredient B by adding, to the said amount of B~l, 5 grams and 10 grams, respectively, of portland ~ -:
. .

9~ 34 cement as con-~ercially availahle (rnade by Nihon Cement Co., Ltd., in the ranye of 30 - 75 micron mesh). Shown hereunde~ in Table 6 are the properties and the foamin~ time of the respective heat insulating materials as so provided.

T~ble 6 Example Cheat insulating . 6 material) No.
Fo~ming time (m nutes) 35 30 15 10 (a) 0.30`0.25 0.27 0.24 Cb~ 0.2 0.3 0.2 0.3 (c) 4.8 5.0 4.8 5.1 (e) _ _ ' _ _ _ P ropertie s _ (B~0.06 0.07 0.06 o.o8 ~ 1_3 ~ 2 Examples~ 9 to 12 Inorganic heat insulating materials 9 through 12 were provided again similarly as in Example 1, with the only exception of changing the ingredient C from C-l to 5 grams of C 2 through C=5, respectively. Shown hereunder in Table 7 are the properties and the foaming time of the respective heat insulating materials as so provided.

~L639~B~34 T.ll-le 7 Exarnplc (heat insulnting _ 10 11 12 Material) No.
_ .
Foamin~ time (minutes) 48 51 45 47 _ (a) O. 24~ 0.30 0. 29 0. 25 _ _ _ (b) 0 . 3 0 . 4 0 . 2 0 . 3 _ . (c) 5.3 5.7 5.6 5.5 (d) _ _ Ge) _ _ P ropertie g (f) _ (~g) 0.07 0.06 0.05 0.07 L ~ ~ - 3 Examples 13 to 16 Inor~anic heat insulatiny materials 13 through 16 were provided again similarly as in Example 1, with the only exception of changing the ingredient D from D-l to 7 grams of D-2 through D=5, respectively. Shown hereunder in Table 8 are the results of the properties and the foaming time, as measured, of the respective heat insulating materials as so provided.

~ ~ -20-~9q~4 r~lbl~ 8 mclterinl) No. 13 _ 15 _ ._ Fo~m~n~ tlme (minutes) 49 47 50 51 (a) 0.31 ~ 0.33 ~ 0.29 0.28 _ . -- . _ _ ~
~b) 0.3 0.4 _ 0.2 0.3 (c) 5.5 4.9 4.9 5.0 . (~ _ = = __ P roperties (f) _ - _ . _ (g) 0,0~ 0.~)7 0.05 _ 0.07 L ~) 1:3 1 2 Examples 17 to 19 ~ norganic heat insulating materials 17 to 19 were provided again similarly as in Example 1, but with further incorporation, as fillers, of 2 grams of fused quartz, sintered ~ -cristobalite and gypsum, respectively, in addition to the inaredients A-D as originally used. Shown hereunder in Table 9 are the results of the properties and the foaming time, as measured, of the respective heat insulating materials as so provided.

_ _ E:x~ le Chcnt insulQting 17 18 _ m~terl~l) No.
~ _. . . _ . .
l~iller f u~ed slntered __ _ qunrtz cris~ob~llte :Ypsum . ~o~mln~ tlme (minute~) 45 45 45 . _ ..
(n) 0.29 0,25 ~ ~
Cb) 0.2 . 0.3 0.2 . _ _ _, (c) 6.2 _ 6-3 6.3 (d) ._ ~ _ _ ~
~e) ~ -Properties _ . ~ ~ _ (8) 0.06 0.07 0.06 . . ___ . .
(h) 2-4 1 -3 2-4 .
_ _ (i) _ _ _

Claims (9)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for manufacturing inorganic heat insulating material, characterized by mixing, into a pasty state in the presence of water, ingredients A, B, C and D, namely:
A. a water-soluble alkali silicate B. alumina cement C. a metal base foaming agent and D. a foam stabilizing agent.

2. A process as claimed in claim 1, in which ingredient A is a water soluble alkali metal silicate.

3. The process of claim 1 or 2, wherein portland cement is added to the ingredient B.

4. The process of claim 1 or 2, wherein mol ratio SiO2/RI2O, with RI representing alkali metal, of the ingredient A is in the range of 1.5 - 4Ø

5. The process of claim 1 or 2, wherein the mixture in pasty state contains water in the amount as would make aqueous solution of the alkali silicate content, in a concentration in the range of 20 60%.

6. The process of claim 1 or 2, wherein the ingredient A is used in a form of aqueous solution in a concentration in the range of 20 - 60%.

7. The process of claim 1 or 2, wherein the ingredients are admixed, taking 100 weight parts of the water-soluble alkali silicate as the basis, of the solids portion of the alumina cement in the range of 100 - 700 weight parts, of the metal base foaming agent in the range of 0.5 - 35 weight parts and of the foam stabilizing agent in the range of 0.1 - 50 weight parts.

8. The process of claim 1 or 2, wherein portland cement is added to ingredient B in an amount of 20 weight parts to 100 weight parts of alumina cement in solid portion ratio.

9. The process of claim 1 or 2, wherein the ingredients are admixed, taking 100 weight parts of the water-soluble alkali silicate as the basis, of the mixture of the alumina cement and the portland cement in the range of 100 - 700 weight parts in solid portion ratio, of the metal base foaming agent in the range of 0.5 - 35 weight parts and of the foam stabilizing agent in the range of 0.1 - 50 weight parts.