SE439795B - VERMEISOLERINGSFORFARANDE - Google Patents

Description

7807826-8 significant amount of beads have passed therethrough.

One of the most important applications of cavity insulation is in the insulation of buildings due to the significant savings in energy consumption that can be achieved. In such applications it is important not only to achieve improved thermal insulation but also to provide satisfactory flame retardant properties, and although expanded polystyrene beads are commercially available which contain a flame retardant additive, the use of such beads with a synthetic polymeric latex binder does not always provide - sufficiently high level of flame protection. We have now developed a method in which a flame retardant can be introduced with the synthetic polymeric latex binder into the cavity, thereby providing good flame retardant properties in the cavity filling composition. The present invention thus relates to a method for providing particles of expanded polymer as thermal insulation between separated surfaces in existing dwellings and other building structures with an air-filled cavity therebetween, the method being characterized in that in the cavity between said surfaces, which are existing inner wall surfaces, in front of an expanded polymer, which contains a synthetic polymer latex binder and an organic bromine-containing compound as flame retardant.

Expanded polystyrene beads are particularly suitable for use as cellular polymer particles in the process of the invention, but other types of cellular, expanded polymers may also be used. As is well known, polystyrene foam particles are conveniently prepared from expandable particles which are produced in the form of beads by suspension or emulsion polymerization techniques, a blowing agent such as pentane being incorporated therein during or after the polymerization. Upon heating of the expandable beads, "pre-expansion" occurs, yielding the polystyrene foam particles suitable for use in the process of the invention. Pre-expansion, which is a well-known step in the polystyrene foam technology, involves steam-treating the expandable beads to achieve an expansion of about 20-30 times their original volume, f. .__ i e- i- _ Is fl í '”nu 7807826 -3 and during cooling, air is allowed to enter the separate cells to raise the internal pressure to atmospheric pressure. These expanded polystyrene foam particles have a spherical shape, an apparent compressed density of e.g. 6-100 g / liter and free-flowing properties. For filling wall cavities, the particle size of the beads should suitably be in the range of 1-10 mm, and for this purpose it is desirable to use self-extinguishing grades of polystyrene beads. A number of additives are known for this purpose, such as brominated or chlorinated organic compounds.

The synthetic polymer latex used as a binder in the process of the invention may be any aqueous, colloidal suspension of particles of a polymer obtained by polyaddition. In general, the colloidal suspension is stabilized by the presence of a suitable surfactant, and most suitable polymers are those obtained by free radical emulsion polymerization. Suitable latexes thus include those based on, for example, styrene / butadiene copolymers, acrylic copolymers, butadiene / acrylonitrile polymers, vinylidene chloride copolymers, butyl rubber, isoprene or preferably polymers or copolymers of vinyl alkanoates or vinyl propylate. A preferred class of latexes is based on vinyl acetate copolymers, in particular on copolymers of vinyl acetate with higher vinyl esters, such as vinyl caproate, vinyl laurate and vinyl <1, od dimethyl octanoate.

It has been found that particularly satisfactory results are obtained if the latex is based on a copolymer of vinyl acetate and a vinyl ester of a carboxylic acid having 6-16, in particular 8-12, carbon atoms per molecule. Such copolymers are commercially available under the trade name "VeoVa". In the latter type of copolymers, the weight ratio of vinyl acetate to higher vinyl ester is from 10:90 to 85:15, preferably from 60:40 to 80:20. The latex may, if desired, contain other additives, such as silica fillers, thickeners, corrosion inhibitors, pigments and water-soluble dyes. _ .__ -._..., ...._._..._.._.._...____.: ........

The organic bromine-containing compound used as a flame retardant component in the process of the invention may be any of the compounds of this type commonly incorporated with polystyrene beads, for example bromophenylalkenyl ethers such as pentabromophenyl allylates, brominated cycloalkanes such as hexabromocyclododecane or organic phosphates such as tris- (2,3-dibromopropyl) phosphate. If the flame retardant is a solid, it can be conveniently and efficiently introduced into the cavity in the form of a flowable suspension concentrate, which as such constitutes a further feature of the present invention and comprises 10-85% by weight of the solid flame retardant, 0.5-15% by weight dispersants, 0.1-10% by weight of suspending agents such as protective colloids and thixotropic agents, 0-10% by weight of additional additives such as flame retardants, eg antimony oxide, antifoams, corrosion inhibitors, stabilizers, penetrants, bacteriostatic agents and tackifiers and as carriers water or an organic liquid, wherein the flame retardant is substantially insoluble; certain organic solids or inorganic salts may be dissolved in the carrier for the purpose of preventing sedimentation or as antifreeze for water, for example ethylene glycols.

The dispersant may be nonionic, such as an ethylene oxide / propylene oxide copolymer, an ethoxylated alkylphenol or a long chain ethoxylated alcohol, or may be of an anionic nature, such as a metal salt, preferably a sodium or calcium salt, of lignin sulfonic acid, methacrylic acid or other polyelectroic acid. . The suspending agent may be a water-soluble polymer, such as a polysaccharide or hydroxyethylcellulose, or may be a finely divided inorganic solid such as bentonite, montmorillonite or other clay powders. The particle size of the flame retardant should suitably be as small as practicable, preferably with a volume median diameter below 10 μm and preferably between 1 and 5 μm. The exact nature and proportions of the components incorporated in such a suspension concentrate are, of course, dependent on the physicochemical properties of the selected flame retardant component, and _ -: Vi ou »i år ä» a -n I. _. Those skilled in the art will appreciate that not every potential dispersant is necessarily sufficiently compatible with every suspending agent and every flame retardant. In the case of pentabromophenyl allyl ethers, good results have been obtained using an aqueous suspension concentrate which contains a naturally occurring polysaccharide and an ethylene oxide / propylene oxide copolymer.

According to a further feature of the present invention, the cellular particles of expanded polymer are advantageously introduced into the cavity by means of a spray gun, in which flows of particles, latex binder and flame retardant are combined in the desired ratio and the resulting mixture is fed into the cavity by the pistol nozzle. Such a spray gun suitably comprises a tube or similar device, arranged to be connected to a particle container, such as a hopper, and with a main nozzle inserted therein, through which air or other gaseous fluid under pressure can be introduced for the purpose of feeding particles. through the tube or the like from the container, and also one or more additional nozzles, through which the binder latex and the flame retardant component are introduced.

For filling wall cavities, the amount of latex is suitably such as to provide 5-10% by weight, preferably 6-8% by weight of solid latex material, based on the weight of the polymer particles. The solids content of the latex itself can be 10-20% by weight, while the total weight ratio of polymer particles to the latex is usually in the range of 10: 1 to 10:10 for these applications. The flame retardant content normally amounts to 0.1-10% by weight, based on the weight of the polymer particles.

Although the latex binder and the flame retardant component, if desired, can be fed separately to the spray gun (or even separately to the cavity), it has been found that in practical use the cavity filling process is substantially simplified if the flame retardant, preferably in the form of a suspension concentrate, is premixed with polymeric binder. coated kg __-._-_._._. t_t_ ___.___ ,. 7807826-8 6 with the resulting mixture, preferably in the spray gun. This method not only simplifies the construction of the spray gun by reducing the number of separate intakes and extra nozzles, but also makes it possible to prepare the mixture of latex and flame retardant centrally and transport this mixture to the various places where cavity filling is to take place.

This procedure thus reduces the number of separate preparation components required at the place where the filling is to be carried out, thereby reducing the need for logistical organization and storage space and also eliminating the need for measures for independent measurement of the amount of flame retardant by the operator. It will be appreciated, however, that such a centralized formulation of the mixture of latex and flame retardant is possible only if the resulting mixture has sufficient storage stability, and its attainment is largely dependent on the use of an appropriate formulation of flame retardant. component. We have found that the use of a suspension concentrate of the flame retardant component generally provides satisfactory storage stability when the component is mixed with the latex binder.

After the cavity has been filled by means of the method according to the invention, the resulting filling is allowed to dry and harden. When sufficient water has evaporated, the latex polymer will coalesce on the polystyrene foam particles and serve as a permanent binder. After wetting the polystyrene particles with the latex but before curing, the free-flowing ability of the particles is reduced somewhat, which prevents unnecessary spillage of bead.

The curing time of the composition - usually 1/2 to 3 hours - depends on several factors, such as ambient temperature and relative humidity, the ability of air to pass and the composition and amount of latex used. In general, the curing temperatures are in the range of 15-40 ° C. The minimum film formation temperature can, if desired, be reduced to as low as 5 ° C by the addition of small amounts of high molecular weight alcohols, for example 1-5% by weight based on the latex. Suitable alcohols for this purpose are polyethylene glycols, polypropylene glycols and ester alcohols.

It will be appreciated that, although the method of the invention is particularly suitable for the insulation of cavities in existing buildings containing cavity wall structures, the method is in no way limited to this application. Thus, blocks or panels used in building structures are often designed with cavities to reduce their weight, and the method of the invention can be used to fill these cavities and improve the thermal insulation properties of the product. other applications, which include many outside the building construction area, are obvious to those skilled in the art.

The invention is further illustrated according to the following exemplary embodiments, in which the temperature indications refer to degrees Celsius.

Example 1 Pentabromophenyl allyl ether (PBPAE) was prepared as a suspension concentrate (SK) containing 65 parts by weight of PBPAE, 1.25 parts by weight of ethylene oxide / propylene oxide copolymer, available under the tradename "Pluronic" P.105, and 0.3 parts by weight of that nature Xantan rubber available under the trade name "Kelzan" XC. This suspension concentrate was mixed in various quantities (listed in Table 1 below) with a latex of a vinyl acetate copolymer with "VeoVa" 10, which is the trade name of a vinyl ester of zz, OC-dimethyloctanoic acid in a monomer weight ratio of 70:30, containing 3% by weight of an anionic emulsifier and having a solids content of 17% by weight and a pH of 4-4.5. a spray gun with polystyrene foam balls with a diameter of 3-5 mm, an actual density of 20 g / liter and containing 0.6% by weight of PBPAE as flame retardant, the mixing ratio being about 60 parts by weight of PBPAE / latex mixture per 500 parts by weight are polystyrene particles. This mixture was then injected at 25 ° into a cavity. bzfgoz: QUÅHTX. After 1 hour, the mixture had hardened in the cavity to an apparent bulk density of 10 g / liter (based on polystyrene), and the flame safety of the filling was evaluated partly by determining the flame extinction time (using the flammability test BS 3837) and partly by "oxygen index" determination, as this method is described in Modern Plastics, March 1970, p. 124-130 (also ASTM D 2863). The exact composition of the various mixtures tested and the results of the flame retardancy tests are given in Table 1 below.

TABLE 1 Composition (parts by weight) Flame safety Polystyrene-I Latex PBPAE-SK Flammability -BS Oxygen index; cellular plastic (input 3837 (time in sec. ASTM D2863 beads with latex) for the flame to go out (% oxygen)) ¿100 12 - i - '18' 100 12 0.5 ll - 100 12 1.0 14 22 100 1.5 1.5 - 100 l2 2.0 2 24.5 Example 2 The vinyl acetate / "VeoVa" latex described in Example 1 was mixed with various amounts (listed in Table 2 below) of the liquid flame retardant tris- (2 , 3-dibromopropyl) phosphate (T23P) and 1% by weight (based on T23P) of gumaryl monostearate, and the resulting mixture was diluted with 2 volumes of water. The diluted latex mixture was injected together with polystyrene foam beads into a cavity by the method described in Example 1; the procedure was performed with both PBPAE-containing beads ("F" beads) and similar beads, with which no flame retardant had been incorporated ("R" beads). Flammability tests were then performed on the cavity filling composition and results in table 2 below caWWTYJ 7807826-8 9 TABLE 2 Flammability, sec for the flame to go out (BS 3837)% T23P (calculated on beads) "F" beads "R" beads 1.5 over 20 over 20 2 , 0 over 20 _ over 20 2.5 2-3 2-3, 0 0 0 LPooR ommff

Claims (8)

7807826-8 'o Patent claim 1. A method for providing particles of expanded polymer as thermal insulation between separated surfaces in existing dwellings and other building structures with an air-filled cavity therebetween, characterized in that in the cavity between said surfaces, which is existing inner wall surfaces, in front of an expanded polymer, which contains a synthetic polymer latex binder and an organic bromine-containing compound as flame retardant. 2. A method according to claim 1, characterized in that the expanded polymer is expanded polystyrene. 3. A process according to claim 1 or 2, characterized in that the latex binder is based on a vinyl acetate copolymer, which constitutes a copolymer of vinyl acetate and a vinyl ester of a carboxylic acid having 6-16 carbon atoms per molecule. 4. A process according to any one of the preceding claims, characterized in that the organic bromine-containing compound is a solid which is introduced into the cavity as a flowable suspension concentrate comprising 10-85% by weight of the solid flame retardant. , 5-15% by weight of dispersant, 0.1-10% by weight of suspending agent and as carrier water or an organic liquid, wherein the flame retardant is substantially insoluble. 5. A process according to claim 4, characterized in that the dispersant is an ethylene oxide / propylene oxide copolymer, that the suspending agent is a polysaccharide and that the flame retardant has a particle size with a volume median diameter below 10 μm. Process according to any one of the preceding claims, characterized in that the organic bromine-containing compound is pentabromophenyl allyl ether. 7807826-8 H Process according to any one of the preceding claims, characterized in that the amount of latex and flame retardant introduced is such as to provide, based on the weight of the polymer particles, 5-10% by weight of solid latex material and 0.1-10% by weight of flame retardant. . 8. A method according to any one of the preceding claims, characterized in that the particles of expanded polymer are introduced into the cavity by means of a spray gun, in which flows of polymer particles, latex binder and flame retardant are combined in the desired ratio, and that it the resulting mixture is discharged to the cavity via the gun nozzle.