EP1116810A1 - Process for making an insulation mold part and insulation mold part for low temperature insulation - Google Patents

Abstract

The invention relates to a method for producing an insulating body part and an insulating body part for low-temperature insulation, in which a pre-fleece (5) is formed from glass fibers, in particular glass staple fibers, and a plurality of pre-fleece layers are stacked to form a stack (8) and pressed together at elevated temperature. Here one would like to be able to implement cold insulation at low cost with good effectiveness. For this purpose, textile glass fibers with an average diameter of at least 6 µm are used as glass fibers and the pre-fleece layers (5) are needled mechanically before being pressed together. <IMAGE>

Description

The invention relates to a method for manufacturing a molded part for low-temperature insulation, in which a nonwoven fabric made of glass fibers, in particular Glass staple fibers, formed and several pre-fleece layers too stacked on top of each other and at elevated temperature be pressed together. The invention further relates to an insulating body molding for low-temperature insulation, with a large number of non-woven fabrics Glass fibers, in which the glass fibers are essentially in lie on a level, is built that presses together are.

The invention is based on a plate as Example of a molded part described. On appropriate However, molded parts can also be produced which have a slightly different shape, for example half shells for the insulation of pipes or L-pieces.

DE 39 29 867 A1 shows high-temperature super insulation and a process for their production in which amorphous Tempered glass fibers are processed into nonwovens and this fleece during a defined time one Exposed to pressure and heat treatment. For this the nonwovens are layered in a container in which a platen can dip.

US 5 330 816 describes an insulation material for the Insulation of refrigerators, freezers or water heaters, that are built with mineral fibers. For this purpose, a glass fiber plate made of glass fibers with a Diameters between 1 and 25 µm, if possible contains no binding agents, placed in a press and to a predetermined strength by spacers is determined, pressed together.

US 5,090,881 describes a method of manufacturing an insulating plate, in which glass fibers with a Diameter between 1 and 25 µm, preferably between 3 and 12 µm, mixed with amorphous silicon particles, which are arranged in the spaces between the fibers become.

US Pat. No. 5,094,899 shows an insulation molded part produced therewith, that can be used in refrigerators.

For the thermal insulation of vessels and containers would you like the heat transfer from one side of the Prevent insulation to the other side of the insulation or at least make the heat flow very small. The Heat flow is largely based on heat conduction and Heat radiation. Convection, i.e. heat transfer through matter, e.g. Gas that is in an area of heat picks it up and delivers it to another area, no longer plays a role in most isolations. The insulating plate therefore has the task of thermal radiation and heat conduction as much as possible prevent. This depends on the temperature range different material requirements and the insulation system because at high temperatures heat radiation, however, at low temperatures the heat conduction prevails. It follows that materials not generally for high temperature applications are also suitable for low temperatures.

Have insulation systems for the low temperature range diverse application possibilities. As examples here refrigerated transport car for the food industry or use in cooling units in commercial or domestic area mentioned. Due to legal The question becomes guidelines and economic constraints for an effective and inexpensive alternative to the insulation processes used so far are becoming increasingly important.

Simple insulation materials currently in use exist from foams, e.g. Polyurethane or other Fabrics with low heat conduction. Also insulation, which consist of fiber materials are, as stated above, known and used. In both cases the gases enclosed in cavities (in the Air) due to their low thermal conductivity as isolation. For higher quality insulation systems this part of the heat conduction is also necessary to reduce. This usually happens through the use of vacuum insulation systems, i.e. by removing the heat-conducting air.

This can be the case with small volumes, for example vacuum jugs or bottles without any major difficulties respectively. For large-scale structures, such as at Refrigerated containers, truck bodies or large refrigerators, is, however, a support for the boundary walls the vacuum system with the help of a filler, to the forces caused by the external air pressure act on the walls to compensate. To be there Thermal bridges that can lead to heat conduction, to prevent or reduce their conductivity, special insulation materials must be used, which in addition to low heat conduction is also sufficient have mechanical stability against pressure, without worsening the vacuum due to outgassing processes.

For such large-area vacuum insulation already microfibers (fiber diameter <3 µm) made of glass used. Microfibers have due to their geometry a good insulation effect. The making of this However, microfibers require considerable effort. Corresponding insulation systems are currently used with good insulation effect in the overall view (Manufacturing costs, maintenance, disposal) relatively expensive or costly.

The invention has for its object an insulation inexpensive to design with good effectiveness.

This task is carried out in a method of the type mentioned at the beginning Art solved in that as a glass fiber textile Glass fibers with a diameter of at least 6 µm are used and the pre-fleece layers before pressing be mechanically needled.

With this procedure you get before Pressing together the pre-fleece layers, handling units, that simplify the production considerably. The The choice of the diameter of the glass fibers has two Benefits. On the one hand, the glass fibers are at least 6 µm diameter not respirable, i.e. health harmless. On the other hand, the glass fibers have sufficient mechanical stability for this diameter, around the individual layers of pre-fleece after needling to hold together so that such a stack out Fleece layers can be handled in one piece, without the risk that the layers will change again seperate. It is therefore possible to lay the pre-fleece layers in a continuous or at least quasi-continuous Process to generate the compression of the Nonwoven layers should then be carried out in batches. Though then arise in the finished product due to the Needling changed alignment of individual glass fibers Areas that could be called a thermal bridge. It has surprisingly turned out that these thermal bridges are not that critical. Possibly this is because the alignment the glass fibers when pressing the Nonwoven layers are basically retained, the but glass fibers lying in the press direction are compressed, be kinked or broken so that their thermal conductivity decreases again. As glass fibers are preferred textile glass staple fibers are used, i.e. fibers of limited length.

Preferably by needling at less than 10% of the fibers cause a change in fiber orientation. Needling is therefore limited to relative few fibers, so the risk of thermal bridges continues is reduced. With such a low degree of needling is mechanical cohesion only weak. But it is enough for the manufacturing process out. The later mechanical stability of the end product is achieved by pressing.

Preferably several needles are needled, that are not needled together, pressed together. This approach has two advantages. On the one hand arise in the contact areas of neighboring Stack, hereinafter also referred to as the "parting plane" become, higher thermal resistances. The heat conduction is reduced. The other is handling simplified. By pressing together you get one considerable reduction in thickness. For example a stack of pre-fleece layers with a height of 20 cm reduced to about 1 cm. A pre-fleece layer stack of 20 cm is still easy to handle. A corresponding one Double-height stacks would be much more difficult to handle. To an insulating plate with the thickness of To get 4 cm, you would even need a stack of 80 cm can handle. Through the described procedure but you can put four partial stacks together in the Insert the press and then press together.

The stack is preferably produced by cross-laying of the preliminary fleece. This allows a continuous Realize process. By coordinating the feed speed of the stacker to the feed speed a recording tape can be accordingly produce thick fleeces.

A soft glass is preferably used. This Soft glass, preferably C glass, is used of temperature and pressure for a certain time Subjected to annealing process. The pressing time is dependent of the desired bulk density and thickness of the material as well as the desired compressibility. These glasses need a slightly smaller one for the tempering process Temperature. Secondly, it is inexpensive. For the third it has excellent thermal insulation properties.

Preferably, the stack or stacks after the Needling cut to predetermined delivery dimensions. After needling is, as I said, the pre-nonwoven layer stack manageable. If you look at him at this stage to the desired dimension, then the Cutting process relatively easy because the plate is still has not reached its final strength. By the pressing results in slight changes in shape, that are still within the tolerance range.

The diameter of the glass fiber is preferably in the range from 8 to 15 µm, especially in the range of 10 up to 12 µm. Surprisingly, it turned out that such thick fibers have excellent thermal Provide insulation. Added to this is the advantage that the Stacks after needling relatively thick fibers are durable in construction.

The task is carried out by an insulating molded part solved type in that the glass fibers have a diameter of more than 6 µm and a maximum of 10% of the glass fibers at least over a part their length have an orientation that is perpendicular to the plane.

The insulating body molded part is therefore as described above Process manufactured. Amazingly arise despite the changed orientation Some of the fibers have relatively good thermal insulation properties.

The proportion is preferably perpendicular to the planes standing glass fibers between 2 and 8%. The smaller the proportion of these fibers, the better the insulation.

There is preferably at least one parting plane, which is not penetrated by vertical glass fibers is. In this parting plane, which is formed by that you have several needles stacked one inside the other are not needled, stacked and pressed, there may be an interruption existing thermal bridge that the insulation effect further improved.

The vertical glass fibers preferably have a variety of changes of direction. This change of direction result from the pressing of the pre-fleece layer stacks. During this pressing, the glass fibers are by needling perpendicular to the planes have been deflected in the direction of the press. When pressing they can only be compressed to a very limited extent. Rather, they are squeezed and fold thereby several times, so that again a relatively long Route arises, which is only a very weak thermal conductivity Has.

The diameter of the glass fibers is preferably in Range of 8 to 15 µm, especially in the range of 10 up to 12 µm. This results in excellent thermal Insulation effects at low manufacturing costs.

Fig. 1

eine schematische Draufsicht auf eine Vorrichtung zum Herstellen einer Isolierplatte,

Fig. 2

einen Vorvlieslagenstapel in einer Presse und

Fig. 3

eine Isolierplatte.

The invention is described below with reference to preferred embodiments in conjunction with the drawing. Show here:

Fig. 1

1 shows a schematic top view of a device for producing an insulating plate,

Fig. 2

a pre-fleece layer stack in a press and

Fig. 3

an insulating plate.

1 shows a device 1 for producing insulating plates 2 made of glass fibers. The glass fibers become one Card 3 fed from a storage vessel 4 and leave the card in the form of a thin fleece 5 on a conveyor belt 6. Here you can get a first look assume that all fibers of the fleece 5 parallel lie on a plane. There are smaller inclinations unavoidable, but don't matter. Important is, however, that practically only a negligible Proportion of fibers protrudes perpendicular to the conveyor belt 6. This quasi one-layer training is described below referred to as "pre-fleece". The nonwoven 5 is one Feeder 7 fed in a manner known per se generates a nonwoven layer stack 8 from the preliminary nonwoven 5, the height of this stack 8 being determined by the Speed at which the belt 6 feeds the preliminary web 5 and the speed at which a tape 9 den Fleece layer stack 8 leads away. The achievable Dikke the pile of nonwoven layers is relatively large, in the end but limited.

The nonwoven layer stack is continuously a needling device 10 fed. There is the pile of nonwovens 8 by a not shown, but known needle arrangement perpendicular to the tape 9 stands, pierce. Doing so will be schematic is shown in Fig. 2, individual fibers 11 deflected and are then practically perpendicular to the plane, in which the fibers of the preliminary fleece 5 lie. Here the needle density is selected so that a maximum of 10% of the Fibers get a different orientation. In many cases even a much smaller percentage will suffice for example 5%.

A needle fleece is placed behind the needling device 10 Decreased 12, not even excessive is heavily compressed. It is almost the same Thickness as the nonwoven layer stack 8, but holds together better and can therefore easily be seen as a unit handle. The needle fleece 12 becomes a cutting device 13 fed by a knife 14 from separates 12 individual blocks 15 from the needle felt. This Blocks have a length that is the dimensions of a predetermined one Insulating plate corresponds. Possibly you can also in the cutting device 13 Trim edges. The blocks 15 become a press 16 supplied, which is shown schematically in Fig. 2 is. The press has two heated pressure plates 17, 18 on. The pressure plates 17, 18 can in the direction of Arrows 19, 20 are moved towards each other, so that after a certain time a plate 21 is formed, as in Fig. 3 is shown.

The glass fibers that form the preliminary fleece 5 have one average diameter from 10 to 12 µm. You should be on in any case be thicker than 6 µm. A glass is a C glass, so a relatively soft glass is used.

In the needling device 10, the pre-nonwoven layer stacks are intended only be loosely assembled. The cohesion must only be so large that the individual Blocks 15 handled and inserted into the press 16 can be. By compressing in the press then the mechanical cohesion of the plate 21 is generated. In the press, the plate 21 is used for compaction heated to a temperature that resulted in a minor Changes in the glass fibers leads. The pressing time is usually more than 10 min. By pressing also set the target thickness of the plate 21. By the If the glass fibers soften, they can become the specified ones Adjust shape. In addition, may still be existing volatiles removed from the plate. This tempering process results in a solidified one and mechanically stable glass fiber plate with excellent mechanical and thermal properties.

As stated above, it is technically relatively difficult the nonwoven layer stack 8 over a certain thickness to manufacture. Because in the press 16 under certain circumstances compression in a ratio of 10: 1 or even 20: 1 can, one would have to have a relatively thick stack of nonwovens 8 have to a desired final thickness of a finished To produce plate 21. To work around this problem one can arrange several blocks 15 in the press 16. In addition to bypassing a pile of nonwoven layers that is too thick 8 the advantage that separation planes 22 are formed are still recognizable in the finished plate 21 are. These parting planes 22 are not made with fibers 11 interspersed perpendicular to the plane of the nonwoven 5 stand. Accordingly, a at the parting planes 22 thermal bridge formed by these fibers 11 is interrupted.

As can be seen schematically from FIG. 3, the Fibers 11 with a different orientation pressed together during pressing. It is shown that these fibers Bend, break or kink several times. You can achieve that the thermal bridge established by such fibers 11 becomes relatively long, so that the thermal conductivity through these fibers 11 even with thicker glass fibers with a diameter> 6 µm not noticeably increased becomes.

Such plates 21 can advantageously be used in vacuum systems be used for cold insulation. Here takes over the insulating plate 21 next to the thermal insulation also the mechanical support of a double wall Vacuum system. Because no binders or the like Additives can be used in the manufacture also no components of the glass fiber plate 21 in Degas vacuum.

Claims (13)

Method for producing an insulating body molded part for low temperature insulation, where a Pre-fleece made of glass fibers, in particular glass staple fibers, formed and several layers of pre-fleece into one Stacked on top of each other and at elevated temperature are pressed together, characterized in that that as glass fiber textile glass fibers with a Diameters of at least 6 µm can be used and the pre-fleece layers mechanically before being pressed together needled. A method according to claim 1, characterized in that by needling less than 10% of the Fibers causes a change in fiber orientation becomes. A method according to claim 1 or 2, characterized in that that several needles stacked together, that are not needled together, pressed together become. Method according to one of claims 1 to 3, characterized characterized in that the stack by cross-laying of the preliminary fleece. Method according to one of claims 1 to 4, characterized characterized in that the pre-fleece with the help of a Cardboard produced as a carding fleece. Method according to one of claims 1 to 5, characterized characterized in that a soft glass is used. Method according to one of claims 1 to 6, characterized characterized in that the stack or stacks after the Needling cut to predetermined delivery dimensions become. Method according to one of claims 1 to 7, characterized characterized in that the diameter of the glass fiber in the range of 8 to 15 µm, especially in the range is from 10 to 12 µm. Insulated body part for low temperature insulation, with a large number of non-woven fabrics made of glass fibers, especially glass staple fibers in which the Glass fibers lie essentially in one plane, is built up, which are pressed together, thereby characterized in that the glass fibers have a Have a diameter of more than 6 µm and maximum 10% of the glass fibers (11) at least over a part their length have an orientation that is perpendicular to level (6). Insulating molded part according to claim 9, characterized in that the proportion of perpendicular to the Levels (6) standing glass fibers (11) between 2 and 8% lies. Insulating molded part according to claim 9 or 10, characterized characterized in that at least one parting line (22) is present that is not vertical Glass fibers (11) is interspersed. Insulating molded part according to one of claims 9 to 11, characterized in that the vertical standing glass fibers (11) a variety of changes of direction exhibit. Insulating molded part according to one of claims 9 to 12, characterized in that the diameter the glass fibers in the range of 8 to 15 microns, in particular is in the range of 10 to 12 µm.

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