GB2101644A - Production of low-flammability heat-insulating layer - Google Patents

Abstract

Low-flammability heat-insulating layers are produced in cavities of masonry or hollow building blocks by introducing foam particles of expanded plastic, preferably expanded polystyrene, and inorganic binder into the cavities. A preferred inorganic binder is an alkali metal silicate in the form of an aqueous solution or suspension. In a preferred embodiment the binder is an aqueous sodium silicate solution having a solids content of 25 to 55% by weight and containing the following additives: a) 2 to 10% by weight of precipitated silica, b1) 5 to 50% by weight of sodium silicate powder or b2) 1 to 30% by weight of slaked lime, and c) 0.05 to 0.5% by weight of a surfactant.

Description

SPECIFICATION Production of low-flammability heat-insulating layers The present invention relates to the heat insulation of masonry and hollow building blocks by introducing foam plastic particles plus a binder into the cavity in the masonry or into the cavities in hollow building blocks.

For heat insulation of cavity walls, insulating materials, for example foam polystyrene particles, are introduced into the cavity. According to a process described in German Laid-Open Application DOS 2,830,914, the foam particles are held together by a binder which is intended to prevent particles from running out of orifices and flaws in the masonry. In this process, a synthetic polymer latex is used as the binder. This latex increases the flammability of the heat insulating layer, consequently necessitating the addition of relatively large amounts of bromine-containing flameproofing agents.

It is an object of the present invention to provide a simpler method of producing lowflammability heat insulating layers in the cavities of masonry.

We have found that this object is achieved, according to the invention, if the foam particles of expanded plastic are held together by an inorganic binder.

Suitable insulating materials are all conventional foam particles of expanded plastic, for example particles of aminoplast or phenoplast foams or of polyurethane foams. The preferred particles are foam polystyrene beads obtained by foaming particulate expandable polystyrene. Their diameter is preferably from 1 to 10 mm, and their bulk density from 5 to 100 g/l.

Suitable binders are the conventional inorganic binders, for example based on cement, lime or gypsum. The preferred binder is an aqueous solution or suspension of an alkali metal silicate, especially sodium water-glass, having a solids content of 25~55% by weight.

The weight ratio of foam particles to binder is preferablyfrom 1:1 to 1:5,especiallyfrom 1:1.5 to 1:3.

The inorganic binder preferably contains 2 10% by weight of precipitated silica as a thickener, 5~50% by weight of sodium silicate powder or 1~30% by weight of slaked lime as a hardening accelerator, and 0.05-0.5% by weight of a surfactant as a foaming agent.

In some cases it can be advantageous to add yet further additives to the foam particles or the binder, for example anti-sedimentation agents or antifreezes, for instance ethylene glycol.

The foam particles and binder are preferably injected separately from one another, by means of a mixing gun, under pressure, into the masonry cavity. There they mix, and the binder gradually sets through evaporation of water and/or through chemical reaction, and thereby ensures cohesion of the foam particles. The setting time is from 10 minutes to 2 hours depending on the water content of the binder, the ambient temperature, the relative humidity and the nature and amount of the hardening accelerator.

The process according to the invention is in particular useful for heat insulation of cavity walls, but can also be used for heat insulation of other cavities of sections of buildings, or heat insulation of hollow building blocks.

Example A binder mixture was prepared from 30 kg of sodium waterglass solution of 50% by weight solids content, 1 kg of precipitated silica, 1 kg of slaked lime and 0.03 kg of foaming agent.

This mixture and, separately therefrom, 16 kg of foam polystyrene beads (diameter 3-6 mm, bulk density 15 kg.m#3) were fed to a spray gun and mixed in a mixing nozzle in the spray head.

The mixture was injected through several holes in the outer shell of a cavity wall. During hardening, the mixture proved sufficiently noncreeping, and its volume remained sufficiently constant. After a setting time of 20 minutes, the mixture was hardened completely. The head insulating layer thus produced had a density of 50 kg.m-3 and a heat conductivity of 0.045 w.m-l.a K#1.

Claims

1. A process for the production of a lowflammability heat-insulating layer in cavities in masonry or in hollow building blocks, comprising introducing foam particles of expanded plastics material plus a binder into the cavities, wherein an inorganic binder is used.

2. A process as claimed in claim 1, wherein the binder is an alkali metal silicate in the form of an aqueous solution or suspension.

3. A process as claimed in claim 1 or 2, wherein the foam particles consist of expanded polystyrene.

4. A process as claimed in any of claims 1 to 3, wherein the weight ratio of foam particles to binder is from 1:5 to 1:1.

5. A process as claimed in any of claims 1 to 4, wherein the binder is an aqueous sodium silicate solution of 25~55% by weight solids content and contains the following additives: a) 2 to 10% by weight of precipitated silica, b,) 5 to 10% by weight of sodium silicate powder or b2) 1 to 30% by weight of slaked lime, and c) 0.05 to 0.5% by weight of a surfactant.

6. A process for the production of a lowflammability heat-insulating layer in masonry and hollow building block cavities carried out substantially as described in the foregoing Example.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (6)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Production of low-flammability heat-insulating layers The present invention relates to the heat insulation of masonry and hollow building blocks by introducing foam plastic particles plus a binder into the cavity in the masonry or into the cavities in hollow building blocks. For heat insulation of cavity walls, insulating materials, for example foam polystyrene particles, are introduced into the cavity. According to a process described in German Laid-Open Application DOS 2,830,914, the foam particles are held together by a binder which is intended to prevent particles from running out of orifices and flaws in the masonry. In this process, a synthetic polymer latex is used as the binder. This latex increases the flammability of the heat insulating layer, consequently necessitating the addition of relatively large amounts of bromine-containing flameproofing agents. It is an object of the present invention to provide a simpler method of producing lowflammability heat insulating layers in the cavities of masonry. We have found that this object is achieved, according to the invention, if the foam particles of expanded plastic are held together by an inorganic binder. Suitable insulating materials are all conventional foam particles of expanded plastic, for example particles of aminoplast or phenoplast foams or of polyurethane foams. The preferred particles are foam polystyrene beads obtained by foaming particulate expandable polystyrene. Their diameter is preferably from 1 to 10 mm, and their bulk density from 5 to 100 g/l. Suitable binders are the conventional inorganic binders, for example based on cement, lime or gypsum. The preferred binder is an aqueous solution or suspension of an alkali metal silicate, especially sodium water-glass, having a solids content of 25~55% by weight. The weight ratio of foam particles to binder is preferablyfrom 1:1 to 1:5,especiallyfrom 1:1.5 to 1:3. The inorganic binder preferably contains 2 10% by weight of precipitated silica as a thickener, 5~50% by weight of sodium silicate powder or 1~30% by weight of slaked lime as a hardening accelerator, and 0.05-0.5% by weight of a surfactant as a foaming agent. In some cases it can be advantageous to add yet further additives to the foam particles or the binder, for example anti-sedimentation agents or antifreezes, for instance ethylene glycol. The foam particles and binder are preferably injected separately from one another, by means of a mixing gun, under pressure, into the masonry cavity. There they mix, and the binder gradually sets through evaporation of water and/or through chemical reaction, and thereby ensures cohesion of the foam particles. The setting time is from 10 minutes to 2 hours depending on the water content of the binder, the ambient temperature, the relative humidity and the nature and amount of the hardening accelerator. The process according to the invention is in particular useful for heat insulation of cavity walls, but can also be used for heat insulation of other cavities of sections of buildings, or heat insulation of hollow building blocks. Example A binder mixture was prepared from 30 kg of sodium waterglass solution of 50% by weight solids content, 1 kg of precipitated silica, 1 kg of slaked lime and 0.03 kg of foaming agent. This mixture and, separately therefrom, 16 kg of foam polystyrene beads (diameter 3-6 mm, bulk density 15 kg.m#3) were fed to a spray gun and mixed in a mixing nozzle in the spray head. The mixture was injected through several holes in the outer shell of a cavity wall. During hardening, the mixture proved sufficiently noncreeping, and its volume remained sufficiently constant. After a setting time of 20 minutes, the mixture was hardened completely. The head insulating layer thus produced had a density of 50 kg.m-3 and a heat conductivity of 0.045 w.m-l.a K#1. Claims

1. A process for the production of a lowflammability heat-insulating layer in cavities in masonry or in hollow building blocks, comprising introducing foam particles of expanded plastics material plus a binder into the cavities, wherein an inorganic binder is used.

2. A process as claimed in claim 1, wherein the binder is an alkali metal silicate in the form of an aqueous solution or suspension.

3. A process as claimed in claim 1 or 2, wherein the foam particles consist of expanded polystyrene.

4. A process as claimed in any of claims 1 to 3, wherein the weight ratio of foam particles to binder is from 1:5 to 1:1.

5. A process as claimed in any of claims 1 to 4, wherein the binder is an aqueous sodium silicate solution of 25~55% by weight solids content and contains the following additives: a) 2 to 10% by weight of precipitated silica, b,) 5 to 10% by weight of sodium silicate powder or b2) 1 to 30% by weight of slaked lime, and c) 0.05 to 0.5% by weight of a surfactant.

6. A process for the production of a lowflammability heat-insulating layer in masonry and hollow building block cavities carried out substantially as described in the foregoing Example.