DE2716152A1 - INORGANIC FOAM - Google Patents

Description

Imperial Chemical Industries Limited, London, Great Britain

Inorganic foam

The invention relates to inorganic foams and, more particularly, to rigid mineral foams.

The invention is a rigid foam with an inorganic cellular structure composed of lamellae of vermiculite.

Vermiculite is a phyllitic silicate mineral, ie a mineral with a layered structure. It can be swollen by allowing aqueous salts to act, after which the structure can be mechanically exfoliated, ie delaminated , into extremely thin lamellae. Other phy lite Si Likat minerals, for example hydrobiotite or chlorite vermiculite, also contain a considerable proportion of vermiculite layers, and their layer structure can also be exfoliated in the same or a similar manner . These vermiculite-containing minerals also produce thin lamellae and are encompassed by the invention. Preferably, however, the blades of vermiculite themselves are used for the manufacture of the foam according to the invention.

709843/0875

Dresdner [Ii κ (Munich)

(M.inchon) loo. 6 / 0-43 804

Z 7 16 1

The preferred rigid foam according to the invention has a cell structure, the cell walls of which overlap one another individual vermiculite lamellae, which are held together by mutual forces of attraction.

The cell structure extends continuously and practically evenly in all dimensions through the volume of what is formed Foam. The overlapping lamellae represent the boundary walls of each cell of the structure, so that in the structure as a whole, the individual slats are present in all possible orientations to a given reference plane. The foam according to the invention thus differs from the vermiculite granules peeled off by heat, which were produced earlier became. In these granules obtained by heating, the mineral has a low density. Within each granule (the one before the peeling due to heat was its own particle) become during Upon heating, the layers of the mineral separate from one another, but remain practically parallel to one another. In addition, there is such a structure only within each granule and does not extend to a continuous structure between granules. This known form of low density vermiculite is not the subject of the invention.

The above-mentioned individual lamellae, which can also be called platelets or flakes, have, for example, a smallest dimension below 0.5 Wn, preferably below 0.05 ^ m and in particular below 0.005 mm> and have approximately the same length or width dimensions of at least that 100 times, preferably at least 1000 times the small dimension.

The density of the foams according to the invention is in the range below 0.5 g / ml, usually below 0.15 g / ml and can be used for

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particularly "light" foams are, for example, down to 0.01 g / ml.

The density can be varied in various ways, for example by introducing different amounts of gas into the suspension or by changing the solids content of the suspension. For a foam of low density, the solids content is expediently 5 to 20% by weight , while for a foam of higher density the solids content can be increased to 30% w / w or more.

The invention also relates to a method of production a rigid vermiculite foam, which is characterized in that a suspension of vermiculite lamellae in a liquid medium, preferably an aqueous liquid medium, introduces gas into the suspension to a To form foam, and the liquid medium evaporates from the foam.

The swelling and exfoliation of vermiculite to form aqueous dispersions of vermiculite flakes are various Publications, for example GB-PS 1 016 385, 1,076,786 and 1,119,305 and by Baumeister and Hahn "Micron", J_, 247 (1976). The ones in these publications described methods can be used in carrying out the method according to the invention. However, it is in the foaming according to the invention preferably a surfactant or foaming agent is present in the suspension before the gas in the suspension is introduced to form the foam, the term "foam" being an expanded form of the entire suspension understand is.

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It is advantageous to choose a surface-active agent or foaming agent that is able to penetrate into the structure of the mineral and thereby cause the mineral to swell and flake. The use of a cationic organic salt which is capable of ion exchange with the cations present in the vermiculite layers is particularly preferred. Particularly preferred cationic surfactants are the hydrocarbon-substituted ammonium compounds known as surfactants. For example, 1 to k hydrogen atoms of the ammonium cation can be substituted by alkyl, aryl, alicyclic or heterocyclic groups.

Examples of preferred cationic salts are n-butylammonium chloride

Isobutylammonium chloride

Isoamylammonium chloride

Cetyl pyridinium bromide

Cetyltrimethylammonium bromide

2-ethylhexylammonium chloride

Dodecylammonium chloride

Lysine monohydrochloride

Ornithine monohydrochloride

and polypeptides in cationic form. Other types of foaming agents or foam-generating surfactants can also be used as additives to the suspension of vermiculite lamellas, used as auxiliaries for other swelling agents, for example alkali chlorides, or in combination with the above-mentioned cationic salts, for example long-chain aliphatic alcohols (for example Cetyl alcohol), alkyl sulfate salts (e.g. sodium lauryl sulfate), N-acyl sarcosinates and long chain aliphatic amine oxides (e.g. oleyldimethylamine N-oxide).

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An alternative class of foaming agents that are advantageously used as additives to the suspension of vermiculite flakes are the proteins known as foaming agents, for example water-soluble proteins (such as albumin or gelatin) or water-solubilized protein derivatives such as hydrolyzed soybeans and hydrolyzed blood or hydrolyzed feathers.

The liquid medium can, if it is an aqueous medium, organic liquids miscible with water, for example the lower alcohols or acetone. Alternatively, the foam can be modified in a non-aqueous medium using Vermiculites as described in GB-PS 1,076,786 are produced.

For foaming, gas or steam can be given off in the suspension of vermiculite lamellae. The gas is preferably the aqueous suspension inert to. For example, air, nitrogen, argon, carbon dioxide, a hydrocarbon, Chlorocarbon, fluorocarbon, or chlorofluorocarbon. It is particularly advantageous to move the gas mechanically through rapid movement, for example by rapidly stirring or beating the suspension to be introduced into it. Alternatively, the suspension rapidly heated and the foam is formed by the formation of gas either in the form of steam, which is formed by the evaporation of water v is, or by gas dissolved in the sample, which is set free.

A two-phase dispersion is supposed to be under a rigid foam to be understood by gas in solid, wherein the solid phase is an essentially continuous inorganic cell structure. Small amounts of organic materials, which are either intentionally added or unintentionally present

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to

are to be present. However, the presence of such an organic material is not essential for the cohesion of the cell structure necessary. However, it can make its properties more valuable Modify way. By removing water from one aqueous dispersion of vermiculite lamellae come the lamellae together and form a coherent film. The cell walls therefore retain the cell structure of the foam according to the invention their mechanical strength largely or entirely due to the fact that the flakes stick together by themselves when the water is removed will. The structure formed is a non-brittle foam. I.e. under stress the structure can be deformed, without crumbling.

The cellular vermiculite is a valuable heat-resistant and heat-insulating material that can be used to fill cavities or as a coating on the outside of materials such as wood or steel parts, in both cases the vermiculite foam acts as a fire protection layer. The vermiculite foam can be produced in the form of panels for subsequent processing or the production of laminates. The vermiculite foam can be used, for example, as the inner layer of a sandwich structure with outer layers made of, for example, wood veneer, paper, asbestos, mica or plastic or vermiculite foil, and such sandwich structures can be used as decorative panels. The vermiculite foam can also be used as an inner layer between plasterboards or foils made of thermosetting resin, for example melamine resin. Such laminates can be used in the construction industry as fire-resistant and / or sound-insulating panels which can be kept ^{at temperatures of approximately 1000 ° C. without disintegrating.} Layers of vermiculite foam can be used as top surfaces by conventional lamination techniques

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Can be applied to polyurethane foam sheets to ensure fire resistance to improve the polyurethane foam core. The foam, i.e. the gas-containing suspensions before drying, can expediently be used to make previously formed vermiculite objects, for example foils or sheets from already dried foam to bind together, so that several foils are glued together and processed into larger objects will. In the same way, the vermiculite granules peeled off by heat can be glued together with the same foam so that a composite structure of the foam according to the invention as a continuous binder between Granules formed from heat exfoliated vermiculite.

For some purposes it may be necessary to make the vermiculite foam waterproof, for example by he is subjected to a treatment with ammonia, as in the brit, Patent application 14 551/77 described.

The following examples illustrate the invention.

example 1

1 kg of vermiculite ore from South Africa, known as "Mandoval micron grade "was in 5» 1 saturated sodium chloride solution for 30 minutes on Refluxed. Excess saline was decanted off and the vermiculite was washed in 5 liters of distilled water. Thereafter the solid was washed five times with 1 liter of distilled water each time on a Buchner filter funnel. The wet vermiculite cake was returned to the reflux vessel and made up for 2 hours with 1.25 moles of butylammonium chloride, made up with distilled Water boiled to a volume of 5 1 * under reflux. After this

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ORIGINAL INSPECTED

By refluxing the solid again as described above washed, with a rapid expansion of the vermiculite to about 6 times its original volume. After standing overnight, the supernatant liquid was decanted off and the 6 liters of swollen vermiculite ore were divided into 2 parts divided by about 3 liters each, and each portion was made up to 4 liters in a large beaker with distilled water.

Then each suspension was mixed for 1 hour with a paddle mixer immersed in the beaker and rotating at 6500 rpm. touched. The suspension was kept near ambient temperature by spraying cold water on the outside of the beaker. With this stirring, air got into the suspension of the lamellae and a appeared on the surface of each suspension Foam. The depth of the foam increased when the suspension was allowed to stand for 30 minutes and about 600 ml of foam was removed from each Suspension removed.

The foam was placed in a mold and dried ^{at 60 ° C. in a well-ventilated oven.} Then a hard vermiculite foam having a density of 0.08 g / ml was taken out of the mold. The foam had conformed to the shape and formed a thin film of vermiculite on its surface.

The suspension of lamellas was beaten again for 60 minutes at high speed and left to stand for a further 30 minutes, after which a fresh amount of foam had appeared. The procedure was repeated a few times using different approaches of Foam obtained from the same suspension. These were combined with one another and converted into a form and in the Oven dried, forming a solid foam with a density of 0.08 g / ml and a mean cell diameter of 0.7 mm became.

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Example 2

A sample of ground vermiculite ore from North America (Zonolite No. A) Was 30 minutes in a saturated sodium chloride solution refluxed and washed thoroughly a few times with distilled water. Then the particles were in for 2 hours an aqueous solution of n-butylammonium chloride is refluxed and then washed again thoroughly with distilled water. During the second wash (conveniently between a few minutes and a few hours) there was a strong swelling of the particles to about 6 times their original size Wet volume. This was then a sample of expanded vermiculite.

Water was filtered off from the aqueous suspension of swollen vermiculite until the weight ratio was about M)% vermiculite solids to 90% liquid water. The suspension was placed in a high-shear mixer (manufactured by Greaves Limited) having a paddle capable of rotating at 6500 rpm, and the suspension was mechanically agitated or macerated for 10 minutes. Air was whipped into the suspension and after the paddle was turned off and the suspension allowed to stand for 5 minutes, a foam several inches deep was above the suspension. The foam was removed with a knife and spread on a dish. The shell containing the foam was placed in a well-ventilated oven at 60 ^° C., and the water was separated off by evaporation, possibly assisted by a fan or a hood in the oven. The dry foam could be removed from the tray as a solid cellular vermiculite foam with a density below 0.1 g / ml and a mean cell diameter of 0 / mm.

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Example 3

A sample of vermiculite (Zonolite No. 4) was treated as described in Example 2, but the suspension was in 60 minutes stirred in the mixer. The density of the foam obtained was 0.035 μ / ml and the mean cell diameter was 0.5 mm.

Example 4

Vermiculite from South Africa was expanded as described in the first section of Example 1. After the solids content of the suspension of swollen vermiculite was adjusted to 2056 w / w, the suspension was stirred until it was homogeneous and passed once through a "rotor-in-stator" mill rotating at a speed of 20,000 rpm . Before the suspension was fed into the shear zone of the mill, air was metered into it at a rate of 10 l / min. The entire suspension was converted into a thick foam which, upon standing overnight, separated into a lower liquid layer containing some of the larger vermiculite particles and another layer of wet vermiculite foam. The foam (which was found to be stable for a few weeks when wet) was removed and ^{dried in a wire mesh form in a well-ventilated oven at 80 °} C. A foam area of 30.5 x 30.5 x 5.1 was obtained cm (12 "χ 12" χ 2 ") having the following characteristics:

Density 0.22 g / ml

Compression P

strength 0.11 MNm "

Thermal conduction _{1 1}

ability 0.000 Wm "K ~

% closed

Cells $ 12

Mean cell diameter 1.5 now

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^ 71615 *

-M-

Example 5

3 kg of American vermiculite was found as in the first section of Example 2 described expanded.

The swollen vermiculite was then divided into 9 parts, each of which was mixed for 45 minutes in a Greaves Mill to make suspensions of defoliated vermiculite. The 9 batches were then combined and the larger vermiculite particles were separated by passing the suspension through a 50 µm sieve. The "classified" suspension thus obtained, which contained about 5% by weight of pests, was evaporated on a large heated counter to increase its solids content to 20J (> The volume increased about 2-fold and the whole suspension became a wet foam with a small bubble size. The foam was spread on a heated dish and dried overnight, with a plate 1 & \ 5 χ 122 χ 0.64 cm (6 ^f χ 4 'χ 1/4 ") was obtained the dried foam had the following properties.:

Density 0.12 g / ml

Compression ₂

strength 0.30 MNm "

Thermal conduction _{1 1}

fMhiglceit O, o6o Wm κ

% closed

Cells 41 #

Average cell diameter 0.2 mm

Example 6

3 kg of South African vermiculite was made as in the first section of Example 1 described expanded. After the expansion

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11 1 b IS

sion, the supernatant water was decanted off, and the swollen vermiculite was mixed in portions of 750 ml for 10 minutes in a household liquefier. The thick, but pourable suspension containing 20 wt -.% Solids. It was foamed as described in Example 5 using a household blender. The foam was then dried overnight in an oven at 90 ^° C., resulting in panels 61.0 x 30.5 χ 0.64 cm (24 "12" χ 1/4 "). Several panels were used of wet foam was layered on top of one another and a 12 "by 12" by 1 1/2 "(30.5 by 30.5 by 3.8 cm) panel was formed and dried in an oven. The physical properties of the thicker plate were:

Density 0.07 g / ml

Compression 2

strength 0.05 MNm "

Thermal conduction _{1 1}

ability 0.048 Wm ' K

% closed

Cells 6%

Average cell diameter 0.5 mm

Example 7

A non-foamed suspension of vermiculite American (20 wt -.% Peststoffe) was prepared as described in Example 5. In this case, the suspension was not aerated, but kept in an oven at 140 ° C. for 3 hours, a dry foam with a density of 0.10 g / ml being obtained by the rapid development of water vapor.

When i never 1 8

17 ' ¹ i <, a suspension of South African vermiculite, which was prepared as described in Example 5, and its solid

7 (; d I Ü 8 7 B ORIGINAL INSPECTED

ci 1 b 1 ht -

Substance content was set to 13 wt .- ^, were in a "Aerosol" container that could be pressurized was introduced. A mixture of 18 g of dichlorodifluoromethane and 12 g of dichlorotetrafluoroethane was placed under pressure in the aerosol container and mixed with the vermiculite paste. By activating A wet foam was applied to a tray of the container's ejection nozzle and air dried for 24 hours. The rigid vermiculite foam thus formed was very fine Pore size (mean diameter of the bubbles = 350 μτη) and one Density of 0.05 g / ml.

Example 9

South African vermiculite (Mandoval "micron" grade) (1 kg.) Was refluxed for 10 hours with a mixture of 4 l of water, 130 g of manganese dichloride tetrahydrate and 0.25 ml of concentrated hydrochloric acid. The product was washed with water and then made up to a total volume of 20 l with water. Then, 75 ml of ¹ N hydrochloric acid and 2 1 30 ^ hydrogen peroxide was added, and the mixture was heated with stirring for 2 hours at 6o ° C, with the vermiculite expanded by absorbing almost all of the liquid present. The mixture was then cooled, filtered, washed with water and made up to 10 with added fresh water. The suspension thus obtained was divided into 4 equal parts and each part was mixed in a 5 liter container with a Greaves H5 series mixer (Mark III) for 1 hour at 65ΟΟ rpm. The combined suspensions were then diluted with water to 16 1 and classified by means of a sieve having sieve openings of 50 min, with a vermiculite suspension with 2.9 wt -% solids was obtained (all of the water added was distilled.)..

By applying heat, so much water was evaporated that the concentration of the suspension was increased to 20 wt .- ^. then

709343/0875

the mixture was cooled and a protein surfactant known commercially as "Nicerol" was added at a concentration of 10 $ v / w of the solid niculite. The mixture was whipped into a foam in a kitchen mixer. After drying in a well ventilated oven at 90 ^° C., the foam had a density of 0.1 g / ml.

Example 10

1 kg of South African vermiculite was refluxed for 2 hours in an aqueous solution of 20% by weight of lithine chloride. After thorough washing η in a Büchner funnel, the original volume of the ore had increased eight times. The mixture of expanded ore and water (10 wt .- # ore) was milled for 1 hour. The larger particles of vermiculite were filtered with a 50 μπι sieve, and the concentration of the suspension was removed by evaporation to 20 wt -% set.. A protein surfactant known as "Nicerol" was added in an amount of 10% by volume, based on the weight of the vermiculite, and the mixture was whipped into a foam in individual parts in a kitchen. After drying in a well-ventilated oven at 90 ^° C., the foam had a density of 0.1 g / ml.

Example 11

As described in Example 4, it was made from North American Vermiculite is a dried foam with an average pore size of 3> 00 mm and a density of 0.01 g / ml.

Example 12

A sample of wet foam prepared as described in Example 6 was mixed with heat expanded vermiculite, so that the mixture becomes 3 ^ voluin- ^ from the wet foam

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^ 716152

and 66 # consisted of the granules. The mixture was in
an oven dried at 9O ⁰ C. The foam thus obtained
had a density of 0.22 g / ml and a compressive strength of 0.12 MNm " ² .

Example 13

From the foam obtained according to Example 5 a plate 62 of χ χ 4 135 mm was cut. It had a density of 0.12 g / ml. This plate was kept in an oven at 1000 ^° C. for 10 minutes. After removal from the oven it was found that the plate was not visibly warped by the intensive heat treatment, ie the dimensions were 61 _× 134 × 4 _{m, the} density dropped to 0.09 g / ml * and the compressive strength was 0.22 Mnm ~.

This shows that the foams of the invention are very heat resistant and therefore according used as fireproofing material who can, as it good dimensional stability with minimal loss of
Have compressive strength.

709843/0875

Claims (1)

P a t e η t a η s j) r ü c h e 1. Rigid foam with an inorganic cell structure, consisting of vermiculite lamellas. 2. Rigid foam having a cell structure, the cell walls are formed by overlapping individual vermiculite lamellae adhering by mutual attraction forces on each other. j5. Rigid foam according to Claim 1 or 2, characterized in that the lamellae have a smallest dimension of not more than 0.5 µm. 4. Rigid foam according to claim 5, characterized in that the lamellae have a smallest dimension of not more than 0.05 MW. [). Rigid foam according to Claim 5 or 4, characterized in that the length or width dimension of the lamellae is at least 100 times the smallest dimension. 6. Rigid foam according to claim 5 »characterized in that the length or width dimension is at least 1000-I'a ■ · ■. :(. ·· where the smallest dimension is. Y. Rigid foam according to one of the preceding claims, characterized in that it is shaped into a coherent and practically uniform film or plate. 70 ^ 343/0875 ORIGINAL INSPECTED Z i 1 6 1 b 8. Foam according to one of the preceding claims, characterized characterized as having a density not exceeding 0.5 g / ml Has. [). Foam according to claim d, characterized in that it has a density of not more than 0.15 g / ml. 10. Process for the production of a rigid vermiculite foam fabric, characterized in that a suspension of vermiculite lamellae is produced in a liquid medium, the suspension gassed to form a foam and the liquid medium evaporates from the foam. 11. The method according to claim 10, characterized in that the liquid medium is an aqueous medium. 12. The method according to claim 10 or 11, characterized in that the gassing is carried out in such a way that one by rapid stirring Carries gas into the suspension. 13. The method according to claim 12, characterized in that the gassing is carried out in such a way that the entire suspension is converted into a foam by whipping. 14. The method according to claim 10 or 11, characterized in that that the fumigation by thorough mixing of the suspension with a vaporizable liquid and evaporation of the liquid in the suspension takes place. 15. Verfanren according to claim 10 or 11, characterized in that that the gassing takes place by rapid heating of the suspension. 7 0.3 / 0875
ORIGINAL INSPECTED 1b. Method according to one of Claims 10 to 15, characterized in that that the suspension is classified before the gassing by separating off coarser particles of Verrniculite. 17. The method according to any one of claims 10 to 16, characterized in that that a surfactant or foaming agent is present in the suspension of vermiculite flakes. 18. The method according to claim 17, characterized in that the surfactant or foaming agent is a cationic organic salt. 19 · The method according to any one of claims 10 to 13, characterized in that that the foaming agent or surfactant is added to the suspension of vermiculite lamellae before fumigation. 20. The method according to any one of claims 10 to 19 *, characterized in that that during the evaporation of the foam with previously formed veriniculite structures, preferably in the form of rigid foam or exfoliated granules, in order to connect these solid vermiculite structures to one another. 21. Shaped body consisting of a foam according to one of claims 1 to 9 · 22. Shaped body according to claim 21, consisting of a sheet of foam with a vermiculite skin over a considerable Part of the surface of the plate. 2j>. Shaped body according to claim 21, characterized in that 7 0 r ü 3/0 8 7 5 I Π 6 1 b it is a laminated body in the form of a foil or plate, which consists of a plate of vermiculite display fabric, which is placed on a Foil or plate made of an organic polymer or plastic is coated on top. 24. Shaped body according to claim 23, consisting of a laminate made of polyurethane foam and vermiculite foam. 25. Polyurethane foam sheet which is covered on at least one side with a cover made of a foam according to one of claims 1 to 9. 26. Shaped body according to claim 21, characterized in that it consists of a vermiculite foam layer between two cover layers consists of panels as they are conventionally used in the construction industry. 27. A method to make objects fireproof, characterized in that the outer surface of the object with a Cover made of a vermiculite foam according to one of the claims 1 to 9 plated. 7 (· ■ · :: / tJ.'J7