DE19960694B4 - Process for producing an insulating body molding and Isolierkörperformteil for cryogenic insulation - Google Patents

Abstract

method for producing an insulating body molding for low-temperature insulation, in which a pre-fleece made of glass fibers, in particular glass staple fibers, formed and several Vorvlieslagen to a stack on top of each other placed and elevated Temperature compressed Be, characterized in that as glass fiber textile glass fibers with a diameter of at least 6 microns are used and the Vorvlieslagen ago The compression are mechanically needled and several in itself needled needles, which are not needled together, are pressed together.

Description

The The invention relates to a method for producing an insulating body molding for low-temperature insulation, in which a fleece of glass fibers, in particular Glass staple fibers formed and several Vorvlieslagen to a stack on top of each other placed and elevated Temperature are compressed. Furthermore, the invention relates to an insulating body part for cryogenic insulation, that with a variety of Vorvliesen of glass fibers, in which the Glass fibers lie essentially in one plane, is constructed, which pressed together are.

The Invention will be described below with reference to a plate as an example of a molded part described. In a similar way but can also moldings produce, which have a slightly different shape, such as half-shells for insulating pipes or L-pieces.

DE 39 29 867 A1 shows a high-temperature super insulation and a method for their production, are processed in the amorphous fibers of hard glass to nonwovens and these nonwovens for a defined time of a pressure and heat treatment are exposed. For this purpose, the fleeces are stacked in a container into which a press plate can dip.

DE 23 20 372 A describes a mat for insulation and filtration purposes, which is also designed for higher temperatures. In the introduction it is stated that the aim is a temperature range above 150 ° C. To fulfill this task, the nonwovens are designed as needled nonwovens, d, h. These are nonwovens that have been mechanically needled.

US 5,330,816 A describes an insulating material for the insulation of refrigerators, freezers or water heaters constructed with mineral fibers. For this purpose, a glass fiber plate made of glass fibers with a diameter between 1 and 25 microns, which contains as possible no binder, inserted into a press and compressed to a predetermined thickness, which is determined by spacers.

US 5 090 981 A describes a method for making an insulating board in which glass fibers having a diameter between 1 and 25 microns, preferably between 3 and 12 microns, are mixed with amorphous silicon particles, which are arranged in the interstices between the fibers.

US 5 094 899 A shows an insulating molding produced therewith, which can be used in refrigerators.

at The thermal insulation of vessels and containers you want the heat transport from one side of the insulation to the other side of the insulation prevent or at least the heat flow very much make small. The heat flow for the most part on heat conduction and heat radiation. A Convection, ie a heat transfer by matter, e.g. Gas that absorbs heat in one area and turns it into one does not play in most isolations Role more. The insulating plate therefore have the task of heat radiation and the heat conduction as good as possible prevention. This results in different depending on the temperature range Requirements for the material and the insulation system, because heat radiation at high temperatures, At low temperatures, on the other hand, heat conduction predominates. It follows that materials for high temperature applications not in principle also for low temperatures are suitable.

Isoliersysteme for the Low temperature range have a variety of applications. As examples, here are refrigerated trucks for the Food industry or use in refrigeration units in the commercial or domestic Area mentioned. Due to legal requirements and economic constraints becomes the question of an effective and cheap alternative to the previously used insulation process more important.

to Time-employed, simple insulating materials consist of foams, e.g. Polyurethane or other materials with low heat conduction. Also isolations, which consist of fiber materials are, as stated above, known and are used. In both cases, the trapped in cavities act Gases (usually air) due to their low thermal conductivity as Isolation. For higher Isolation systems it is necessary also this portion of the heat conduction to reduce. This usually happens through the use of vacuum insulation systems, i. by removal the heat-conducting Air.

This can be done with little volume, such as jugs or bottles still without much difficulty. In large-scale structures, such as in refrigerated containers, truck bodies or large refrigerators, however, a support of the boundary walls of the vacuum system with the aid of a filler is required to compensate for the forces acting on the walls by the external air pressure. In order to prevent thermal bridges, which can lead to heat conduction, or to reduce their conductivity, special insulating materials must be used, in addition to a low heat conduction also have sufficient mechanical stability against the pressure, without deteriorating the vacuum by Ausgasungsprozesse.

For such large-area vacuum insulation were already microfibers (fiber diameter <3 microns) made of glass. Microfibers indicate their geometry a good insulation effect. The production of these microfibers However, it requires a considerable effort. Accordingly are currently used insulation systems with good insulation in the overall view (production costs, care, disposal) relative expensive or costly.

Of the Invention is based on the object, an isolation with good Efficiency inexpensive too shape.

These Task is characterized by a method of the type mentioned by solved, that as fiberglass textile glass fibers with a diameter of at least 6 microns used be, the pre-batt layers before mechanical compression needled and several self-needled stacks, one below the other not needled, be squeezed together.

With This procedure is already available before pressing The Vorvlieslagen handhabere units that make the production quite essential simplify. The choice of the diameter of the glass fibers has this two advantages. On the one hand, the glass fibers are at least 6 μm in diameter not respirable, i.e. no risk to health. For another, the glass fibers at this diameter sufficient mechanical stability to after the needlepunching the individual Vorvlieslagen hold together so that such a stack from Vorvlieslagen quasi one piece can be handled without the There is a danger that to separate the layers again. It is therefore possible to use the pre-fleece layers in to produce a continuous or at least quasi-continuous process, However, the compression of Vorvlieslagen then make batchwise. Although then arise in the finished product due to the needling amended Alignment of individual glass fibers Areas that could be called a thermal bridge. It But surprisingly proved that this Thermal bridges even not so critical. possibly This is due to the fact that the alignment Although the glass fibers obtained in principle during compression of Vorvlieslagen remains, but the compressed in the press direction optical fibers, kinked or broken, so that their thermal conductivity decreases again. When Glass fibers are preferably used textile glass staple fibers, So fibers with limited length. This use of multiple stacks has two advantages. On the one hand arise in the contact surfaces adjacent stacks, which are also referred to below as "parting line", higher thermal resistance. The heat conduction is thus reduced. On the other hand, the handling is simplified. By compressing receives you get a significant reduction in thickness. For example, a Stack of Vorvlieslagen with a height of 20 cm to about 1 cm reduced. A Vorvlieslagenstapel of 20 cm can still handle well. A corresponding stack of twice the height would be far more difficult to handle. To an insulating plate with the strength of 4 cm, you would have to even handle a stack of 80 cm. By the described You can proceed but four sub-stacks together in the press insert and then press together.

Preferably Needling changes to less than 10% of the fibers the fiber orientation causes. Needling is limited so on relatively few fibers, so that the risk of thermal bridges on is reduced. With such a low needling grade although the mechanical cohesion is only weak. He is enough for the Production process off. The subsequent mechanical stability of the final product is achieved by the pressing.

Preferably one creates the stack by crosslapping the Vorvlieses. This can be to realize a continuous process. By adjusting the feed rate of the cross stacker on the feed rate of a recording tape can be adjusted accordingly produce thick fleeces.

preferably, a soft glass is used. This soft glass, preferably C glass, becomes using temperature and pressure for a certain time Subjected to annealing process. The press time depends on the desired density and thickness of the material as well as the desired compressibility. These glasses need something for the tempering process lower temperature. On the other hand, it is cheap. Third, it has excellent Thermal insulation properties.

Preferably, the stack or stacks are cut after the needling to predetermined delivery dimensions. After needling, as already mentioned, the pre-batt pile is manageable. If you bring it to the desired dimension at this stage, then the cutting process is relatively easy because the plate has not yet reached its final strength. By pressing erge At most, there are minor changes in shape which are still within the tolerance range.

Preferably The diameter of the glass fiber is in the range of 8 to 15 microns, especially in Range of 10 to 12 μm. Surprisingly it turned out that such Thick fibers provide excellent thermal insulation. in addition comes the advantage that the Stack after needling relatively thick in fibers Construction are.

The Task is by a Isolierkörperformteil of the type mentioned solved in that the glass fibers have a diameter of more than 6 μm and at most 10% of the glass fibers at least over one Part of their length have an orientation that is perpendicular to the plane, and at least a dividing plane is present that is not perpendicular Glass fibers interspersed.

The Isolierkörperformteil is thus produced by the method described above. Amazingly, arise despite the changed Alignment of a portion of the fibers relatively good thermal insulation properties. In the dividing plane, which is formed by the fact that you have several needles Piles that are not needled together, dealing and squeezes, there is an interruption of a possibly existing thermal bridge, the the insulation effect further improved.

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

Preferably have the vertical glass fibers on a variety of directional changes. These changes of direction result during the pressing of the pre-fleece layer stacks. In this pressing are the glass fibers, by needling are deflected perpendicular to the planes, in the press direction. When pressed, they can be compressed only very limited. They are rather compressed and fold thereby several times, so that again a relatively long Range arises, which has a very low thermal conductivity.

Preferably the diameter of the glass fibers is in the range of 8 to 15 microns, in particular in Range of 10 to 12 μm. This results in excellent thermal insulation effects at cheap Production costs.

The Invention will be described below with reference to preferred embodiments described in more detail in connection with the drawing. Herein show:

1 a schematic plan view of an apparatus for producing an insulating plate,

2 a pre-fleece layer stack in a press and

3 an insulating plate.

1 shows a device 1 for making insulating panels 2 made of glass fibers. The glass fibers become a clutter 3 from a storage vessel 4 fed and leave the clutter in the form of a thin fleece 5 on a conveyor belt 6 , In this case, it can be assumed in the first approximation that all the fibers of the fleece 5 lie parallel to a plane. Smaller tendencies are unavoidable but do not matter. But it is important that practically only a negligible proportion of fibers perpendicular to the conveyor belt 6 projects. This quasi-single-layered training is referred to below as "Vorvlies". The fleece 5 becomes a stevedore 7 supplied, in a conventional manner from the pre-fleece 5 a fleece layer stack 8th generated, the height of this stack 8th is determined by the speed with which the tape 6 the fleece 5 feeds and the speed with which a tape 9 the fleece layer stack 8th dissipates. The case achievable Dic ke of the nonwoven layer stack is indeed relatively large, but limited in the end.

The nonwoven layer stack is continuously a needling device 10 fed. There is the fleece layer stack 8th by a not-shown, but known per se needle assembly perpendicular to the tape 9 stands, pierced. In doing so, as shown schematically in 2 is shown, individual fibers 11 deflected and then stand practically perpendicular to the plane in which the fibers of the Vorvlieses 5 lie. Here, the needle density is selected so that a maximum of 10% of the fibers receive a different orientation. In many cases, even a significantly smaller proportion will suffice, for example 5%.

Behind the needling device 10 becomes a needle felt 12 decreased, which itself is not over-compacted. It basically has almost the same thickness as the nonwoven pile 8th but holds together better and therefore can be easily handled as a unit. The needle felt 12 becomes a cutting device 13 fed with the help of a knife 14 from the needle punched fabric 12 individual blocks 15 separates. These blocks have a length corresponding to the dimensions of a predetermined insulating plate. Optionally, you can in the cutter 13 also crop the other edges. The blocks 15 become a press 16 fed into the 2 schematically is shown. The press 16 has two heated pressure plates 17 . 18 on. The printing plates 17 . 18 can in the direction of the arrows 19 . 20 be moved toward each other, so that after a certain time a plate 21 arises, as in 3 is shown.

The glass fibers, which are the fleece 5 form, have a mean diameter of 10 to 12 microns. They should definitely be thicker than 6 μm. The glass used is a C glass, ie a relatively soft glass.

In the needling device 10 should the Vorvlieslagenstapel be joined together loosely. The cohesion need only be so great that the individual blocks 15 handled and in the press 16 can be inserted. By compacting in the press 16 then becomes the mechanical cohesion of the plate 21 generated. In the press 16 becomes the plate 21 heated to a temperature which leads to a slight change in the glass fibers. The pressing time is usually more than 10 min. By pressing, the target thickness of the plate is also 21 established. By softening the glass fibers they can adapt to the given shape. In addition, any remaining volatile components are removed from the plate. This annealing process gives a consolidated and mechanically stable glass fiber plate with excellent mechanical and thermal properties.

As stated above, it is technically relatively difficult to stack the nonwoven sheet 8th to produce beyond a certain thickness. Because in the press 16 Under certain circumstances, a compression ratio of 10: 1 or even 20: 1 can be done, you would have a relatively thick layer of nonwoven layers 8th have to a desired final thickness of a finished plate 21 to create. To work around this problem, you can in the press 16 several blocks 15 Arrange. This has in addition to bypassing a too thick pile of nonwoven layers 8th the advantage that parting planes 22 are formed, which also in the finished plate 21 still recognizable. These dividing planes 22 are not with fibers 11 interspersed, perpendicular to the plane of the Vorvlieses 5 stand. Accordingly, at the parting planes 22 one through these fibers 11 formed thermal bridge interrupted.

How out 3 can be seen schematically, the fibers 11 compressed with changed orientation during pressing. It is shown that these fibers multiply bend, break or buckle. One achieves that by such fibers 11 reasoned thermal bridge becomes relatively long, so that the thermal conductivity through these fibers 11 even with thicker glass fibers with a diameter> 6 microns is not significantly increased.

Such plates 21 can be advantageously used in vacuum systems for cold insulation. This is done by the insulating plate 21 In addition to the thermal insulation and the mechanical support of a double-walled vacuum system. Since no binders or similar additives are used in the production, no components of the glass fiber plate can 21 outgas in a vacuum.

Claims (11)

Process for producing an insulating body molding for low-temperature insulation, in which a pre-fleece made of glass fibers, in particular glass staple fibers, formed and several Vorvlieslagen to a stack on top of each other placed and elevated Temperature compressed Be, characterized in that as glass fiber textile glass fibers be used with a diameter of at least 6 microns and the Vorvlieslagen are mechanically needled prior to compression and several in needled piles that are not needled together, compressed become. Method according to claim 1, characterized in that that by needling changes less than 10% of the fibers the fiber orientation is effected. Method according to claim 1 or 2, characterized that he creates the stack by crosslapping the Vorvlieses. Method according to one of claims 1 to 3, characterized that he produced the fleece with the help of a card as a carded fleece. Method according to one of claims 1 to 4, characterized the existence Soft glass is used. Method according to one of claims 1 to 5, characterized that the or the stacks after needling to predetermined delivery dimensions get cut. Method according to one of claims 1 to 6, characterized that the Diameter of the glass fiber in the range of 8 to 15 microns, especially in Range of 10 to 12 μm lies. An insulating body molding for cryogenic insulation, which is constructed with a plurality of Vorvliesen glass fibers, in particular glass staple fibers in which the glass fibers lie substantially in a plane, which are pressed together, characterized in that the glass fibers have a diameter of more than 6 microns and maximum 10% of the glass fibers ( 11 ) at least a part have an orientation perpendicular to the plane ( 6 ), and at least one parting plane ( 22 ) is present, not from vertical glass fibers ( 11 ) is interspersed. Insulating body part according to claim 8, characterized in that the proportion of perpendicular to the planes ( 6 ) standing glass fibers ( 11 ) is between 2 and 8%. Insulating body molding according to claim 8 or 9, characterized in that the vertical glass fibers ( 11 ) have a plurality of changes of direction. Insulating body molding according to one of claims 8 to 10, characterized in that the diameter ( 1 ) of the glass fibers in the range of 8 to 15 microns, in particular in the range of 10 to 12 microns.