DD146172A5 - VERMICULITE COMPOSITIONS - Google Patents

Abstract

The invention relates to a vermiculite composition for use preferably in the construction industry for the production of walls, ceilings, Fuszboeden and many other components. The aim of the invention is to provide a storable, well-transportable vermiculite composition. According to the invention, the composition is a good-flow, substantially dry powder composition containing vermiculite particles in the form of lamellae, preferably less than 50 microns. The composition further contains an additive consisting of particles of a metal oxide or hydroxide, preferably of magnesium or calcium. The water solubility of the additive should not be more than 10 g / l, possibly less than 3 g / l, and have a size order of 1 to 20 * m. The composition of the invention may contain from 5 to 90% of additives and mineral constituents. Preferably, the proportion of vermiculised lamellae is 20%. For easier transport, the compositions according to the invention can be compressed into blocks, tables or pellets.

Description

21 ζ & Λ i % fi% J> H ^s

Vermiculite compositions

Berlin, August 8, 1980 AP C 04 B / 215 643 GZ 56 076 18

Field of application of the invention

The invention relates to compositions comprising vermiculite and particularly well-flowing dry powder compositions in vermiculite-cleaved form »

The compositions according to the invention are used in particular in the construction industry, for example for walls, ceilings or floors, temporary living quarters, office partitions, furniture, fire doors, brick lining of furnaces and fire chambers, insulating coverings for electrical equipment »

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It is known that the coated silicate mineral vermiculites can be increased by the action of hydrous salts. Thereafter, the structure can be cleaved by mechanical shear reforming of the resulting aqueous suspension to yield thin slabs called "vermiculite lamellae".

Other coated silicate minerals, for example hydrobiotites and chlorite vermiculites, also contain a significant proportion of vermiculite layers. These may also be enlarged and split in the same or a similar way to give thin lamellae "and it must be understood that all such minerals are included in this term which are included by this specification."

The term "vermiculite lamellae" refers to particles

1 ι rrn

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of cleaved vermiculites which are plates less than one tenth of a micrometer (10 ") thick, usually less than one hundredth of a micron (10") thick.

Moreover, it is known, for example, from GB-PS Nos. 1,016,385 and 1,119,305, US-PS No. 4,130,687 and DE-OS No. 27 41 857, that aqueous solutions of vermiculite lamellae can be used. to be able to form molded solid articles composed of vermiculite lamellae, for example fire-resistant thin sheets and foams * The solid articles are made by removing water from the aqueous vermiculite suspensions, the vermiculite lamellae attracting each other by their own mutual forces of attraction »The aqueous suspension can be poured into molds on frames; for example, rigid foams are produced by gasification of the suspension of vermiculite lamellae before they are shaped and the water is removed. "

In the known processes for the production of solid products from vermiculite, the products are prepared directly from an aqueous suspension of vermiculite lamellae. "Aqueous solutions are not storage-stable and cause certain transport difficulties"

Aim of the invention

The aim of the invention is the provision of transportable and storage-stable vermiculite compositions for the production of foams and films »

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Explanation of the essence of the invention

The invention has for its object to provide a vermiculite composition in dry, well-flowing powdered form available «

According to the invention, the well-flowing, substantially dry powder composition contains vermiculite particles in lamellar form.

According to the present invention vermiculiter slats are major advantages in a well-flowing, dry powder prior to forming shaped solid articles in vermiculite lamellae by the conversion aer aqueous suspension. For example, we have generally observed that foaming products made from dry powder, especially spray-dried powders, surprisingly have a lower density than foams prepared directly from an undried aqueous suspension without a visible loss of compressive strength; an improvement in density above 20 % was achieved without a significant drop in compressive strength. A further advantage arises in terms of the stability and storage characteristics of the dried powder as compared to the aqueous suspension, especially when the composition contains additional materials, for example additives designed to increase one or more properties of the products derived from the composition ,

According to the present invention, there is obtained a well-flowing, substantially dry powder composition of vermiculite lamellae,

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Preferably, the composition is the product of spray drying an aqueous suspension containing vermiculite lamellae. Other forms of drying may be used as well. For example, a slurry of vermiculite lamellae can be dried with the quick drying technique. "Any commercial atomization drying equipment can be used." The atomizing apparatus can be a rotary disk. be a nozzle or a spray head «*

As stated above, one of the main advantages of the dry powder composition compared to the aqueous suspension, stability and storage ability when added with an additive intended to have one or more properties such as density, compressive strength or resistance to decomposition by water ( Water resistance) of solid products, especially foams made from this composition. "According to the invention, there are obtained stable, well-flowing, dried powder compositions containing an intimate mixture of vermiculite lamellae and one or more additives intended therefor. Properties of solid products made from vermiculite compounds "

Particularly preferred are compositions wherein the additives are in particulate form »

Particularly advantageous is the addition of particulate metal oxides, which give a basic reaction in water, especially magnesium oxide and calcium oxide "

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They provide a significant improvement in the compressive strength and water resistance of low density foams made from compositions of the invention. An example of a specific composition of the invention is therefore a stable, free-flowing dry powder composition comprising an intimate mixture of vermiculite lamellae and particles of a metal oxide or hydroxides which gives a basic reaction in water, especially magnesium or calcium oxide ·

The compositions of the invention are usually prepared by drying, especially atomization drying, an aqueous suspension of vermiculite lamellae. In the case where the composition contains a filler, ζ, Β _{β is} a particulate metal oxide, this filler may be added before, during or after the suspension is dried. For convenience and to ensure intimate mixing of the ingredients, the additives (provided that they do not interfere with the drying of the suspension) may be added to the suspension prior to the drying process; in such a case, the additives are added to the suspension prior to, during, or after enlargement or shear shaping. The additive is generally added just prior to drying, especially in those cases where the additives give a suspension of limited stability. For example, the additive may be measured in the suspension as a powder or slurry adjoining the spray head of the atomization drying apparatus. "

The dry powder compositions of the invention may, if desired, under pressure in pellets, tablets or

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Blocks are deformed for easier handling and easier transportation »

In using the compositions of the invention for forming shaped solid products such as sheets or foam, the composition is suspended in an aqueous medium to form a suspension or a slurry, to form for conversion by drying and, if appropriate, by pressing or pouring and gasification (if a foam is desired) to transform into the desired product «

It has been observed that when a composition according to the invention containing an additive floats in water, a slow reaction between the vermiculite fins and the additive can take place, for example, when the additives react as an inorganic base in water. While this reaction may be desirable for improving the physical properties of the products, it may be disadvantageous, for example, in terms of bubble size and density of foaming products. "

Accordingly, problems may arise in the treatment of the aqueous suspensions derived from the compositions of this invention, especially where rigid low density foams are desired as final products. Mindful of the natural nature of the additive material, mindful of the end product to be formed.

The additives in compositions of vermiculite lamellae contain inorganic materials which. Containing oxygen

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They often contain only one element and oxygen, for example, powdered oxides such as magnesia, calcia, fused or solidified oxides in particulate form, glass in a final divided form containing powdered and fibrous glass.

Other oxygen-containing useful materials are oxycidal salts, for example, carbonates, sulfates, boron silicates, and phosphates. Many general filler materials involving minerals may be suitably and advantageously used, for example, those containing carbonate fillings, especially calcium or magnesium carbonates, silicate fillings, especially kaolin, powdered shale and mica portland cement, and various forms of silica, for example sand , The oxides that are suitable include silica, titania, and zinc oxide, while the preferred oxides are boron oxides, calcium oxide, aluminum oxide, and magnesium oxide.

The additives may also be naturally occurring materials (such as clay, bentonite, fuller's earth and diatomaceous earth), synthetically prepared, existing forms of individual parts (z _e as lozenges or fibers molten material such as glass) or synthetic minerals (e.g., B * aluminum silicates ), and the surface of each of these materials can be advantageously treated to provide greater adhesion to the lamellae of the vermiculites when a suspension of the composition is dried in water to form a solid product.

Powdered organic materials, for example dextrin

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and polysaccharides may be included in the compositions. Preferred are inorganic particles which have a density substantially less than the intrinsic density of the material of which they are composed, for example, particles which are cellular, hollow or otherwise empty, without being porous on the outside "A particularly suitable series of particles are hollow microspheres, z" B ", those selected from aer " fly ash ", or micro gas flasks made synthetically from glass or silicate. Low density particles are particularly useful in the present invention because solid products formed by the compositions have a significantly lower density than is normally found with inorganic or mineral products. This is especially true when the solid product has a cellular or foam form and the added inorganic particles (even preferably of low density) are dispersed in a vermiculite cell mass ₆

Inorganic, light blocks were prepared using hollow glass microspheres as inorganic particles by forming an aqueous suspension of a mixture of spheres and vermiculite lamellae. The mixture is then aerated or gassed and then dried between flat plates to form a low density, non-combustible foam Achieves "Typical inorganic foam blocks, even those filled with microspheres, have much higher densities than those produced from the compositions of this invention *

Foam blocks made from the compositions of the invention and inorganic particles consisting of particles

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include de materials, a much higher compressive strength have (z * as three times larger) than other inorganic foams, and they can also compressive strengths of typical or common inorganic cellular blocks having much higher densities (eg "B, higher ctor by F _a 2 or 3), adjust «

The mixing ratio of vermiculite lamellae and other particles can vary over a wide range from as low as 5 % of the weight of non-vermiculite particles to compositions containing by weight 90 % of other materials and only 10 % vermiculites Containing 20 % vermiculite lamellae To achieve properties that are significantly different from vermiculite lather, at least 5 % of other particles are preferably used by weight. The vermiculite lamellae promote better adhesion to the other particles when the lamellae are present at at least 20 % of the total weight of the composition.

Products prepared from the compositions of the invention are generally rigid materials, but do not exhibit the brittleness which have many inorganic compositions, for example, ceramic or glass _e "They are suitable for production of sheets, boards, bricks or blocks used in various industries, especially in the construction industry «

The use of the products may be decorative or exclusively functional in areas where some or all of the advantages of low density, non-flammability, pressure

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- 10 -

strength and heat or sound insulation properties are required, such as walls, ceilings or floors, temporary living space, office partitions or furniture, fire doors or walls, masonry of furnaces or fire chambers and protective coverings for electrical equipment where discharges may occur.

The products can be easily coated with other materials, preferably but not exclusively non-flammable, to produce elements with different surface designs or surface properties. "One example is the use of vermiculite sheets to produce easy-to-use building panels with good appearance and wear resistance To produce surface

As indicated above, the preferred additives for incorporation into the compositions of the invention are solid, particulate inorganic materials. "A class of these materials that provide a good combination of improving the properties of vermiculite articles with ease of handling are basic oxides, have a limited solubility in water, for example, a solubility in water not greater than 10 g / l and preferably not greater than 3 g / l _e oxides whose solubility is greater than 10 g / l tend to very strong flocculation of aqueous vermiculite suspensions. Such suspensions are difficult to treat because they can not be processed into final products sufficiently quickly because flocculation prevents the formation of acceptably strong articles. Preferred are solid, particulate materials which are oxides or hydroxides of alkaline earth metals, preferably oxides

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or Hydroxides of Calcium or Magnesium "A particularly preferred material is magnesium oxide because this material has a particularly desirable combination of properties for improving vermiculite compositions. Magnesium oxide gives foam products made from vermiculite lamellae, both water resistance and compressive strength, and allows low density foams to be made solely from vermiculite lamellae.

According to one aspect of the invention, there is provided a free-flowing dry powder composition containing vermiculite lamellae and magnesium oxide particles.

The particles of magnesia are preferred within the size range of 1, by up to 20 μm. It has been found that samples of magnesia in the lower half of this series give foams that are firm and of low density. "

The behavior of the particulate material added to the vermiculites when the suspension floats in water, for example the rate of solubility of the particulate material in water, and hence the ratio at which ions are formed, can be determined by surface treatment of the particles , z, B, overstretching of the particles with water-soluble films or heat treatment of the particles to partially melt the surface layer of each particle.

The solid particulate material, especially the oxides or hydroxides of alkaline earth metals, is

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preferably in the composition in concentrations of 1 % to 40 % " particularly advantageously from 5 % to 15 % of the weight of the vermiculites, present"

Magnesium oxide is most advantageously greater than 3 % w / vv (weight to weight concentration) and less than 15 % w / w present. Higher concentrations can be used without significant benefits *,

For the formation of any dry powder composition described herein, we prefer vermiculite lamellae which have already been classified. For example, all vermiculite particles larger than 50 will be eliminated »

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The invention is illustrated but in no way limited by the following examples, in which all parts and percentages are by weight unless otherwise indicated.

Example 1;

A 20 kg mixture of South African vermiculite (Mandoval micron grade) was bubbled through for 25 minutes 25 1 of a saturated salt solution in a 50 1 reflux kettle; after this time, it was thoroughly washed in deionized water, filtered and then returned to the 50 liter kettle. The vermiculite was then passed through for 25 minutes 25 l of an 1 N-butylammonium chloride solution. After thorough washing in the

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The aqueous suspension of swollen vermiculites is adjusted to 20 % massive concentration and then 30 minutes in a Hobart vertical slicer (Model VCM 40) at one speed Milled from 3000 revolutions per minute «The larger particles are removed from the suspension by passing the suspension through a vibrating sieve (dilution to 15 %) having an opening size of 50 μm. The resulting classified suspension containing vermiculite lamellae of particle size less than 50 in order to contain, in a Niro "Production Minor" -Zerstäubungstrocknungsapparat spray dried "Using a temperature of 330 ⁰ C at the spray head and 110 ⁰ C at the bottom of the collecting chamber a Yield of 3 kg / h. of a spray dried powder with the density of 220 kg / rn reached.

The vermiculite powder is then dry blended with 10 % of its weight of "light magnesium oxide" in a Kenwood chef shaker. Water is added to the mixture to obtain a 20% vermiculite slurry, from which foam is formed by 4 minutes of continuous vigorous beating. The foam is poured on a plate with the dimensions "6 χ 6" and dried on a heated tray at 70 ⁰ C.

The properties of the dried foam are shown in Table 1 following Example 8.

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- 14 Example 2

A spray-dried powder of vermiculite lamellae having a particle size of <50 μm is prepared as described in Example 1. A 20% suspension in water is shaken in a Kenwood chef shaker and 17 % by weight of magnesium hydroxide powder vermiculite, is added and mixed with the foam for 1.5 minutes. The wet foam is placed in a mold and treated as in Example 1. The properties of the dried foam are shown in Table 1.

Example 3

The procedure of Example 2 is repeated except that 9 % of a calcium hydroxide powder is used instead of magnesium hydroxide. "The properties of the dried foam are shown in Table 1,

Example 4

Vermiculite ores are swollen and ground as described in Example 1, and the suspension is spray dried without spaying as in Example 1. The spun dried powder has a bulk density of 320 kg / m. The powder was mixed with water to give a 20 10 % of "light" magnesia based on the weight of the vermiculites were added and a dried sheet of foam was prepared in Example 1. The properties of the dried foam are shown in Table 1.

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A wet foam of a 20% vermiculite slurry is prepared as described in Example 2 and 7.4 % of dextrin based on vermiculite is added. The properties of the dried foam sheet are shown in Table.

Example 6

A spray-dried vermiculite powder made from a slurry of particle size <50 μm was placed in the hopper of a continuous foam-making machine used in the food industry (an "Oakes" type 4M mixer) was metered at the bottom of the hopper to produce a 20% slurry of vermiculite. This porridge was foamed and poured continuously onto a conveyor belt. After aeration and drying, the foam had the properties shown in Table 1,

Example 7

Sputter dried vermiculite powder was made from a slurry having a particle size less than 50 % and mixed with 10 % "light" magnesium oxide. Then, the dry blend was passed through a hopper of an "Oakes" blender (Type 4M). Water was continuously metered at the bottom of the hopper to obtain a 20% suspension. "The foam was poured, and after ventilation and drying, the foam sheet had the properties shown in Table 1,

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Example 8

Vermiculites powder prepared from a slurry containing fins less than 50 μm in volume was mixed in water to obtain a suspension containing 20 % vermiculite. The suspension was foamed in a Kenwood Chef mixer. No additive was used. The properties of the foam are shown in Table 1:

additive table 1 You foam 160 pressure resistance ³ ) _p (MN / nr) Ex MgO % Addition mix 140 0.62 No. Mg (OH) ₂ (on micromini) Time 140 0 * 41 1 Ca (OH) ₂ 10 4 130 12:30 2 MgO 17 1.5 110 0.29 3 dextrin 9 1.5 62 12:20 4 no 10 1.5 97 12:01 5 MgO 7.4 2 95 12:40 6 no - - 12:04 7 Examples 9 10 Annex 1 8th - - · until 12

Sputter dried vermiculite powder was produced as described in Example 1. The powder was blended in a Kenwood chef blender equipped with a shaker,

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mixed with water to obtain a 20% slurry. "Boric acid powder was added to the suspension, which was then thoroughly mixed and foamed." The foam was poured onto a plate and dried on a tray at 70 ^° C. The properties of the dry foam become The above procedure is repeated three times (Examples 10, 11 and 12) except that boric oxide powder was used instead of boric acid. Foaming properties are shown in Table II:

additive Table II Density (kg / m3) Compressive strength (MN / m ² ) Boric acid boric oxide boric oxide boric oxide 107 172 277 112 0.184 0.333 0.362 0.111 Ex no. Example 13 % Addition (on Vermicu lite) 9 10 11 12 10.64 16 · 67 15 · 16 .16,67

A 5% suspension (classified to 50 μm) of vermiculite was prepared as described in Example 1 and sputter dried in a Niro Mobile Minor sputtering dryer. The suspension was passed through a peristaltic pump to a turbine which drives a spray atomizer head (24,000 revolutions per minute). The foam flows through a drying chamber through a

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Bunsen burner is heated with gas. Initially, the hot gases move opposite to the foam (or "spray" Α "de Ü _e), and lower in the chamber a counter flow of gases causes the dry particles · The dried powder and the gas counter-current to pass from the bottom of the drying chamber a washing cyclone, and the separated dried powder is collected in a preheated glass cylinder to prevent condensation when it is cooled «

The feed rate of the slurry was 750 to 800 cm h "at such a speed steady state conditions were at an inlet temperature in the drying chamber of 180 ⁰ C and an outlet temperature of 100 ⁰ C is reached ·

The product was a free-flowing, dried powder containing vermiculite lamellae as demonstrated by analysis using a transmission electron microscope clearly showing the plate-like structure for the powder. The diameters of the particles were mainly in the range of 0 _e 5 bis 0.2 "It was observed that shaking the powder in air resulted in a 2.5-fold increase in the volume of the powder due to the entrainment of air. Outward air blew off the surface as bubbles, and the volume returned to five times the original value. Slight movement of the powder resulted in an almost complete return to a solid powder.

The dry, free-flowing powder was then mixed with water to give a 5% slurry, and various plates were prepared by pouring the slurry into films and depositing

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2 ΐ 56-43 - is- '

taking the water from the films «The tensile strength of the various plates was measured in each case

-? and it became a tensile strength in the range of 16,000 kNm

_2

found out to 20,000 kNm.

For comparative purposes, plates were used in the same manner from a 5% suspension as in the feed to the spray dryer, that is, "without drying the suspension." The tensile strength of these plates was generally lower than that of the spray dried powder

- 2

a maximum of over 16,000 kNm has been recorded.

Example 14

Vermiculite ores were passed through a saline solution, washed, then re-circulated through an n-butylammonium chloride solution as described in Example 1. The resulting suspension (13.5 % solids) of swollen but uncomminuted vermiculites was fed directly into the atomizer of a spray dryer as described in Example 13 and dried there as a powder. The feed

3 - 1

approach speed was 800 cm h at an inlet temperature of 180 ⁰ C and an outlet temperature of 100 C "

The product was a free-flowing dry powder. The investigations of the powder under an optical stereomicroscope showed that the particles had a plate-like composition.

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Vermiculite sheets made by casting or molding an aqueous paste or slurry of vermiculite compositions as described herein, whether with or without gasification, may be used as a fire-resistant coating or layers, for example in the production of foam laminates, and especially isocyanate based foams, such as polyurethane and polyisocyanurate foams.

For example, the vermiculite sheet may be continuously formed by extruding an aqueous paste or slurry of vermiculite compositions onto a carrier tape which may be a porous mesh, further drying the sheet with hot air and an isocyanate-based foam mixture on this sheet applied. It is processed by a commercially available press described as "A newly developed continuous urethane foam continuous coating machine" published in "Gumm and Plast Age" 1966, Iss. 47, No. 1, page 57, or the Sheet metal is supplied as a floor covering to a coating process, as described in UK Pat. No. 1,053,192 or as a center core in a coating process, as described in UK Pat. No. 1,136,046. In all cases, the isocyanate-based foam may contain glass fibers or other reinforcements to improve the stiffness and fire performance of the laminates.

Claims (9)

8. 2 * 1980 AP C 04 Β / 215 643 GZ 56 076 18 - 21 - 1. Good-flowing, substantially dry Pulverzusammen-,. containing vermiculite particles, characterized in that the vermiculite particles are vermiculite lamellae " 2. A good-flowing powder composition according to item 1, characterized in that it is the product of spray-drying an aqueous suspension containing vermiculite lamellae, Powder composition according to item 1 or 2, characterized in that it contains one or more additives intended to improve one or more properties of the solid products made from the composition. 4 «Powder composition according to item 1, 2 or 3, characterized in that it contains an additive which is a compressive strength improver. 5 «powder composition according to point 1 to 4, characterized in that it contains an additive which is better water resistance. 6 »powder composition according to item 3, 4 or 5, characterized in that the additive is a particulate material which shows a basic reaction in water. 8. 2. 1930 AP C 04 B / 215 643 GZ 56 076 18 - 22 - 7 "powder composition according to item 6, characterized in that the particulate material is a metal oxide or hydroxide, 8, powder composition according to item 7, characterized in that the metal is magnesium » 9 'Powder composition according to item 7, characterized in that the metal is calcium « Pulver »Powder composition according to item 3, characterized in that it contains at least 20 Gevv, ~% vermiculite lamellae. He powder composition according to item 10, characterized in that it contains at least 5 % additives « 12. A powder composition according to item 6, characterized in that the additive is a particulate material having a water solubility not higher than
10 g / l has. 13 »Powder composition according to item 12, characterized
in that the water solubility of particles
existing material is less than 3 g / l » 14 «Powder composition according to item 8, characterized in that the particulate material is magnesium oxide whose particle size is 1 to 20 microns» 8. 2 "1980 AP C 04 B / 215 643 GZ 56 076 18 - 23 - 15. Powder composition according to any one of the preceding claims, characterized in that the vermiculite particles are smaller than 50 microns « 16 «Process for the preparation of a well-flowing dry powder composition, characterized in that the drying of an aqueous suspension of vermiculite lamellae takes place under conditions in which the vermiculites remain essentially as lamellae« 17 «Method according to item 16, characterized in that the drying is a spray-drying or a levitation-drying process« Method according to item 16 for the preparation of a composition according to any one of items 3 to 15, characterized in that the additive is incorporated in a suspension of vermiculite lamellae and the mixture is dried by a rapid drying process. 19 «Method according to item 18, characterized in that the additive is a particulate material which is stored as a powder or slurry in the suspension and the mixture is immediately spray-dried« 20 «Process according to point 16 to 19, characterized in that the compositions are pressed after drying under pressure for easier transport» 21 «Process for the preparation of solid, shaped articles of vermiculite, characterized in that it contains the 8. 2. 1980 AP C 04 Β / 215 643 GZ 56 076 18 - 24 - Distribution of a powder composition in an aqueous
Medium, according to items 1 to 6, to form a slurry and the drying of the slurry takes place during the formation of the solid article. 22 «Method according to item 21, characterized in that the porridge is foamed before forming and drying the solid article _e 23. vermiculite article, characterized in that it is produced by a process according to point 21 or 22, 24 »dry powder composition according to item 1, characterized in that it contains an inorganic oxide or an oxysauric salt to a greater extent. Dry powder composition according to item 1, characterized in that it is more commonly used
Filling material includes » 26 "Powder composition according to item 1, characterized in that it contains to a greater degree a naturally occurring mineral" 27. Dry powder composition according to item 1, characterized in that it is a powdery to a greater extent
contains organic material, 28 «dry powder composition according to item 1, characterized in that it contains to a greater degree particles which are hollow microspheres« _8β 2. 1980 AP C 04 Β / 215 643 GZ 56 076 18 - 25 - 29 »Aqueous composition, characterized in that it is prepared by the addition of water to a composition according to items 1 to 15 and 24 to 28. 30 'A molded article containing vermiculite lamellae, characterized in that the article is made by removing water from a shaped aqueous composition according to point 29'