SE501927C2 - Heat expandable compsn. - contains alkali metal silicate, softener and expansion medium - Google Patents

Abstract

The compsn. is expandable under heating, and contains alkali metal silicate, a softener, and an expansion medium.

Description

5Û1 927 l0 15 20 25 30 35 'be difficult 2 latex dispersions or mixtures thereof. However, it will be apparent to one skilled in the art that many other alkali metal silicate miscible plasticizers can be used. The plasticizer should be monoethylene glycol. be included in such a large amount that it is flexible enough to expand at least 2, preferably times its own volume while retaining the content, however, should be so large that the adhesive capacity of the composition deteriorates to an unacceptable level. In general, it is preferred that it contain from about 5% to about 30% by weight, in particular from about 10% to about 20% by weight of plasticizer. the composition is to be able to from about 4 to about 6 insulating ability. The expanding agent should be at least by a factor of 5, a factor of from about 8 to about 80 on heating, preferably at a temperature of about 80 to about 200 ° C, preferably about 80 to about 120 ° C. The expanding agent can be, for example, expandable graphite or increase its volume significantly, preferably with microspheres. It is especially preferred that the expansion agent comprises heat-expandable microspheres with a thermoplastic shell enclosing a functioning volatile liquid. When heated, the polymer shell softens at the same time as the liquid sphere expands and increases its diameter by a factor of about 2 to about 5. The thermoplastic consists of as a blowing agent evaporating whereby the micro shell can be polymers or copolymers polymerized from monomers such as vinyl chloride , acrylic or styrene, or mixtures of 5 to the microsphere and may include, for example, freons thereof. The blowing agent preferably constitutes from about% by weight of such as trichlorofluoromethane, hydrocarbons such as n-pentane, i-pentane, about neopentane, butane, i-butane, or other blowing agents conventionally used in microspheres of the type indicated herein. Expanded microspheres should have a diameter not greater than about 500 microns, preferably not greater than about 100 microns, especially about 80 microns. It is advantageous - it is not larger than appropriate to use as small spheres as possible, but it is possible to obtain microspheres with a diameter of less than about 1 μm at a reasonable cost. Examples of suitable, lower limit except in cases where the filler contains 501 927 3 commercially available microsphere product have a thermoplastic nitrile copolymer and should contain can be Expancel (R), which shell of a vinylidene chloride / acrylic isobutane as a blowing agent. The composition suffices with the volume of from about 4 to about 6, at the expanding agent expanding agent to increase a factor of at least 2, preferably the above temperatures. If it consists essentially of microspheres as above, the composition preferably contains from about 2% to about 40% by weight, especially from about 10% to about 30% by weight of expanding agent.

The mechanical properties of the composition are improved if it also contains one or the risk of gelation during prolonged storage, often up to 6 or more fillers. To reduce 12 months, the fillers used should be substantially stable in alkali metal silicate solutions, which fillers containing larger amounts increase the molar ratio SiO 2: M 2 O, soluble calcium which forms sparingly soluble calcium silicate, soluble sulphate which forms sodium sulphate. unlike, for example, in cement production, not A large for example excludes soluble silicon or Thus, sand containing large amounts of quartz should be used. however, the number of fillers commonly used in binders can be used, alone or in admixture. Several of these contain silicon and / or calcium which, however, are so tightly bound that they are essentially inert in alkali metal silicate solutions. Examples of useful fillers are kaolin, fatspat, periite, cenospheres (ex fiiiiteßl), titanium dioxide, various iron oxides, aluminum trihydrate, muscovite, diatomite, talc or dolomite. Regarding dolomite, it should not be present in too high levels as it contains calcium which to some extent can go into solution. Some fillers, such as titanium dioxide, also act as color pigments. If the filler particles are too large, the risk of sedimentation during storage increases. about 100 μm, especially less than about 80 μm. There is no critical whereby a desired color can be obtained.

It is preferred that the diameter of the particles be less than one or more components which slowly dissolve in the silicate, it being preferred that the particle diameter exceed about 1 μm. Otherwise, for example if kaolin is used, particles with a diameter down to about 0.1 μm or less can be used without problems. The amount of filler added depends on the desired consistency of the binder, which in turn is governed by how it is intended to be applied. In general, a content of from about 20% to about 120% by weight, preferably from about 30% to about 100% by weight of filler based on the amount of dry alkali metal silicate, is preferred.

The invention also relates to a method of preparing an expandable composition as above by adding an aqueous solution containing alkali metal silicate with a plasticizer and an expanding agent which expands on heating. Optionally, one or more fillers can also be mixed in. The additions can be made in any order at a temperature from 0 to about 50 ° C, preferably from about 15 to about 35 ° C. If an acid-stable filler is used, its dispersion can be facilitated by first treating it with an acid in a slurry, preferably by slurrying the filler in an aqueous solution with the silicate solution. soluble in the acid, after which the slurry is mixed Preferably a hydro-organic acid is used, for example formic acid, acetic acid, propionic acid, valeric acid, malonic acid, succinic acid, adipic acid, maleic acid, fumaric acid, glutaric acid, lactic acid, citric acid, malic acid, tartaric acid, tartaric acid , diglycolic acid, or salicylic acid. For preferred amounts and other characteristics of the constituent components, reference is made to the description of the composition above.

Finally, the invention relates to the use of the composition described above as a fire-protecting insulating material. Until use, it is stored suitably airtight and then applied by spraying, filling or in another suitable way. It solidifies and can itself in one or a couple of days, depending on the thickness of the applied layer, when water is allowed which possibly Depending on evaporation, which heating can be accelerated with moderate heat treatment. expansion agent included, it expands at a temperature of about 80 to 200 ° C with a temperature of about 50 to 200 ° C. In the expanded state it can withstand 850 ° C without collapsing volume factor of about 2 the temperatures _at at least or otherwise broken down.

However, the composition according to the invention also has other uses. Thanks to the excellent adhesive properties, it can be used, for example, as a heat expander - to obtain tight adhesive joints in hard-to-reach spaces and adhesive joints that penetrate bare glue, whereby it is possible in porous materials.

The invention is illustrated in the following exemplary embodiment, which, however, is not intended to limit the same.

Unless otherwise stated, all levels are by weight.

EXAMPLE 1: 400 grams of sodium water glass with a SiO 2: Na 2 O molar ratio of 2.8 and a dry matter content of 45% were mixed with 100 grams of glycerol. Then cell 461 (R> (microspheres with a diameter of 5 to 30 μm containing isobutane was added which through two 45 grams of expanding agent and expands at 120 ° C) and the mixture was stirred for about 30 minutes was obtained. Finally, 300 grams of kaolin was added and 100 grams of cenospheres, after which the mixture until a smooth putty was obtained.The temperature was always about 25 ° C. About 10 grams of the product was allowed to dry for 90 days.When heated to 200 ° C, its volume increased 5 times.

EXAMPLE 2: 300 grams of sodium water glass with a molar ratio of SiO2: Na2O of 3.3 and a dry content of 37% and 100 a molar ratio of SiO2: K2O of 3.4 and a dry content of 35% were mixed with 100 grams of acrylate dispersion Bayer so9 (R) (35% dry matter, 700% Then added 50 grams of Expancell 82O (R) (microspheres with a diameter from until a homogeneous mixture was stirred for about 1 hour grams of potassium water glass with elongation). 5 to 30 μm containing isobutane as blowing agent and expands at 80 ° C) for about 30 minutes until obtained. Finally, 250 dolomite and 100 were added and the mixture was stirred with a homogeneous mixture of grams of kaolin, 100 grams of cenospheres, after which the mixture was left for an hour to about 24 hours. stirring approx. 1 smooth putty 25 ° C. Approx. 10 grams When heated to obtained. The temperature was the whole of the product was allowed to dry at 90 501 927 6 200 ° C, its volume increased 5 times.

Claims (9)

10 15 20 25 30 35 501 927 7 PATENT CLAIMS 1. Heat-expandable composition, characterized in that it contains alkali metal silicate in aqueous solution, an alkali metal silicate-miscible softener, and an expansion agent which expands on heating. 2. A composition according to claim 1, characterized in that the plasticizer is selected from glycerol, acrylate dispersions, monoethylene glycol, latex dispersions or mixtures thereof. 2, k ä n n e- A composition according to claim 1 or the cartoon plasticizer is included in such a large enough flexible to be able to expand its own volume therefrom, that the amount of the composition is at least 2 times to maintain the insulating ability, while the content is not so great that the adhesive ability of the composition deteriorates to an unacceptable level. of claims 1-3, characterized in that the expanding agent comprises in a thermoplastic shell enclosing a volatile liquid acting as a blowing agent. 4. Composition according to any heat expandable microspheres with 5. A composition according to claim 4, characterized in that the unexpanded microspheres have a diameter not greater than about 500 μm. Composition according to any one of claims 1-5, characterized in that it contains sufficient expanding agent to be able to increase the volume by a factor n e t e c k n a d of at least 2 when heated to a temperature of about 80 to about 200 ° C. 7. Composition n e t e c k n a d in that it comprises a filler. 8. A composition according to any one of 1-7, characterized in that the alkali metal silicate has a molar ratio of SiO 2: M 2 O from about 2 to about 4, where sodium, potassium or mixtures thereof. 9. A process according to any one of claims 1-6, characterized in that M is a heat-expandable composition preceding claim, characterized in that an aqueous solution containing the addition of alkali metal silicate is added. with at least one plasticizer and an expanding agent that expands upon heating. Section 10 Use of a heat-expandable composition according to any one of claims 1-8 as fire-protective insulation.