MXPA97002802A

MXPA97002802A - Ac insulating body

Info

Publication number: MXPA97002802A
Application number: MXPA/A/1997/002802A
Authority: MX
Inventors: Werner Dietrich Karl; Thomas Heinz
Original assignee: Bayer Aktiengesellschaft
Priority date: 1994-11-04
Filing date: 1997-04-17
Publication date: 1997-06-01

Abstract

A heat-insulating body, composed of: a) a hard plastic foam reduced to powder and, if necessary, a porous inorganic material and b) a film that surrounds component a), where the film has been emptied on the film that surrounds the component a) and then has hermetically sealed

Description

HEAT INSULATING BODY FIELD OF THE INVENTION It is known to produce heat insulating bodies (vacuum panels) from a porous material and a gas impermeable film that wraps around it, making the vacuum in the existing "hollow space" through the porous material. The porous material may be composed of a porous material in bulk, but also a hard foam. The film is usually composed of combinations of several layers, being solved by the various different layers committed, as a diffusion barrier for various gases and mechanical strength. BACKGROUND OF THE INVENTION Most current vacuum panels on the market have a core of bulk inorganic material, usually based on silicates. In EP-B-188 806, hard foams based on polyurethane (PUR) are described as filling material for vacuum panels. The problem in this procedure is to achieve the necessary cellular opening through the correct choice of the recipe and by maintaining certain parameters of the procedure, since the hard polyurethane foams are predominantly closed cell. Another problem in the use of hard PLR foams as support material for vacuum panels is the exhaust gases of volatile components REF: 24446 as amines, blowing agents, possibly also monomers. An advantage of hard PU foams vis-à-vis porous inorganic bulk materials is, on the other hand, their exact dimensioning as a finished vacuum panel, as well as their exact stability. DESCRIPTION OF THE INVENTION Surprisingly, it has now been found that economically obtaining an outstanding support material for vacuum panels by obtaining by porous foam grinding a porous bulk material and processing it to vacuum panels, analogously to porous silicate bulk materials. For this purpose, hard foams are preferably used, such as those that occur in the recycling of valuable materials, the PUR foam, which occurs in the recycling of refrigerators, being particularly preferred. The object of the invention is, therefore, a heat insulating body, composed of: a) a hard foam of plastic reduced to powder and, if necessary, a porous inorganic material and b) a film that surrounds the component a), the vacuum having been made in the film that surrounds component a) and hermetically sealed afterwards. According to the invention, it is preferred that: - The plastic foam to be crumbled is a polyurethane foam that comes, preferably, from the process of recycling of refrigerators, The powder of the plastic foam has a particle size of 0.01 mm at 1 m, The volatile components of the plastic foam powder have been removed before coating with the film, by conditioning at temperatures of 50 to 250 ° C, preferably 120 to 200 ° C, optionally under reduced pressure, powder of the plastic foam before coating with the film, at pressures of 0.5 to 5 bar, preferably 1 to 3 bar, and as a coating film a multilayer film, preferably a polyethylene / aluminum film or a polyethylene film / polyvinyl alcohol, Porous silicates are used as porous inorganic material. For the vacuum panel obtained according to the investment, all known films are taken into consideration, for example combinations of films such as those which are also used for the production of ordinary commercial vacuum panels. Mention may be made by way of example: combinations of polyethylene films with polyvinyl alcohol films or polyethylene films with aluminum films.

As foams to be used according to the invention, basically all hard plastic foams are taken into consideration. Polyurethane foams are preferred. Although the films used for vacuum panels already have a high gas impermeability, however, they are not a barrier to gases / vapors. Penetrating water vapor, in particular, can have a negative effect on the vacuum and, therefore, on the insulating properties of the vacuum panel heat. In order to avoid this, vapor-absorbing substances, for example those based on silicates or aluminum oxide, in amounts of 10 to 90% by weight, preferably 20 to 50% by weight, can be used according to the invention. The comminution of the pure hard foam can be carried out according to the invention, for example, by grinding, abrasion or peeling.; If necessary, you can also simply crush larger pieces of foam.

The fineness of the porosity can be adjusted according to the invention, on the one hand, by the intensity of the grinding process, on the other hand by the fineness of the cellular structure of the foam to be ground. It can be advantageous according to the invention to pre-press the foam powder at pressures of 0.5 to bar, preferably 1 to 3 bar, then the pressed part is processed to vacuum panel.

As porous inorganic material to be used, if appropriate, porous silicates are preferably considered in accordance with the invention. The porous inorganic material is optionally employed in an amount of 0.1 to 80% by weight, preferably 20 to 50% by weight, based on that of the hard plastic foam reduced to powder. EXAMPLE OF PREFERENCE Prior to 2.5 bar, 1,000 g of hard foam milling of PUR obtained from an old disassembled refrigerator were pre-pressed by grinding the foam contained therein. The pressed piece thus obtained of about 2 cm thick, after a drying of 2 hours to 100 seconds, is cut with measures 40 x 40 cm and then coated with a film composed of the layers: polyethylene / polyvinyl alcohol / polyethylene. The "bag" thus obtained, filled with ground PUR is subjected to a vacuum of 0.001 bar. The edges of the film are vacuum welded. The vacuum panel thus obtained has a heat transfer coefficient? of 10 mW / SKm. It is noted that, in relation to this date, the best method known to the applicant to carry out the aforementioned invention is that which is clear from the present description of the invention. Having described the invention as above, property is claimed as contained in the following:

Claims

CLAIMS 1. Heat insulating body, characterized in that it is composed of: a) a hard foam of plastic reduced to powder and, if necessary, a porous inorganic material and b) a film that surrounds the component a), where in the film that surrounds the component a) the vacuum has been made and then sealed hermetically. Heat insulating body according to claim 1, characterized in that the plastic foam to be comminuted is a hard polyurethane foam. Heat insulating body according to claim 1 to 2, characterized in that the plastic foam powder has a particle size of 0.01 to 1 m. Heat insulating body according to claim 1 to 3, characterized in that, before being wrapped with the film, the volatile constituents of the plastic foam powder have been removed by conditioning at temperatures of 50 to 250 ° C, preferably 120 to 200 ° C, if necessary at low pressure. Heat insulating body according to claim 1 to 4, characterized in that the plastic foam powder is pressed beforehand at pressures of 0.5 to 5 bar, preferably 1 to 3 bar. Heat insulating body according to claim 1 to 5, characterized in that a multilayer film is used as the coating film, preferably a polyethylene / aluminum film or a polyethylene / polyvinyl alcohol film. Heat insulating body according to claim 1 to 6, characterized in that silicates are used as the porous inorganic material.