DE29521460U1 - Fire-proof, transparent pane element - Google Patents

Description

Degussa Aktiengesellschaft .1 .**j ."*..**· ;*9*5*0*Q%7 PO / GM 60311 Frankfurt I *"!· II ·* * '";

Fireproof, transparent pane element

The invention relates to transparent pane elements based on plastic panes that can be used as noise protection elements. In particular, the invention relates to improving the fire properties of transparent pane elements with a transparent plastic pane with embedded monofilament plastic threads that are suitable for preventing or reducing the formation and falling of loose fragments in the event of the plastic pane breaking.

Noise barriers made of plastic are known, for example, from EP 0 407 852 A2 (= US-A 5,040,352). The plastic panels of this known type fulfil their task of preventing the formation and falling of loose fragments in an excellent manner. Stripes, ornaments or figures can also be embedded in the plastic panels described to protect birds.

A translucent building board is known from Austrian patent specification 263 298, which contains a partially metallized fabric cast into it. The fabric is a reinforcement of the building board, but cannot prevent the formation of individual fragments in the event of a break, since in the event of a break, a fabric breaks together with the building board due to the high strength of the plastic material. In addition, the fine light openings in the fabric prevent the building board from being transparent, so that they can only be used as light elements, not as panes. In addition, metallization of the fabric can cause reflexions or reflections, which are on the one hand disturbing and on the other hand

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on one side can create the illusion of transparency that does not exist.

DE-U-84 35 283 discloses transparent building panels in which individual parts that could be created in the event of breakage are secured by external safety ropes. The intended fragments are relatively large and can break into further, still relatively large free fragments. These known panels can be added with strips (or similar) for the purpose of bird protection, for example.

From "Swiss Engineer and Architect", No. 13, 1988 , pages 3, 79 and 380, soundproof panes are known which break into loose fragments. For the purpose of bird protection, 5 mm wide vertical stripes can be etched onto these panes. This additional effort is expensive, increases the risk of soiling the pane and is not very aesthetically pleasing.

DE 43 26 232 A1 discloses plastic composites made of incompatible plastics, whereby at least two mutually incompatible plastics are coextruded with good adhesion between the layers of the multilayer plastic composite. Apart from the continuous production, the composite body presented does not differ in any way from the elements known from, for example, EP-PS 0 407 852. In each case, without an additional bonding agent between the two plastics, a reinforced plastic element is obtained either discontinuously in the casting process or continuously by coextrusion, which, in the event of the matrix (preferably acrylic glass) breaking, is characterized by the property of the second plastic material to hold the resulting fragments together. This splinter bond is based on the ability of the embedded plastic threads to

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stretch without tearing. This holds fragments of the matrix together.

Due to the aforementioned properties, the use of transparent noise protection elements made of acrylic glass is often preferred over other materials when constructing noise barriers on public roads.

Although the risk of such a noise protection element breaking and fragments falling onto the road is significantly reduced when a vehicle collides with it, all plastic elements known to date and mentioned here still have various, in some cases serious, disadvantages.

When a vehicle crashes, there is a serious risk that the plastic elements, whose matrix consists of highly flammable plastics, will ignite. The danger posed by burning noise protection elements is almost more serious than flying splinters. On the other hand, making the plastic matrix flame-resistant is either relatively expensive or comes at the expense of other properties, such as transparency. There is therefore an urgent need for noise protection panels with increased fire safety.

In addition, the surfaces of known acrylic glass noise protection elements are often scratched when cleaned, as they get dirty relatively easily, which in turn has a negative impact on the durability of the panels. If the noise protection elements are not cleaned, their suitability as transparent elements is called into question in the long term. If the panels are coated to be scratch-resistant, they can be cleaned with brushes, etc., but the scratch-resistant coating is relatively expensive. An easy-to-clean, inexpensive noise protection element is therefore very desirable.

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Finally, the known noise protection elements also often suffer from relatively low bending stiffness. This means that with known elements relatively small distances between fastening posts or that with so-called free-standing systems the upper edge of the panel bends dangerously far. This can lead to the entire element breaking. Otherwise the dimensions of the elements are unnecessarily restricted.

The object of the present invention is therefore a pane element based on transparent plastic panes of the type described above, which, without giving up the positive properties of the known noise protection elements, simultaneously improves their fire behavior. Furthermore, the improved plastic pane should be easy to clean, in particular with mechanical devices such as rotating brushes etc., without having to worry about scratching the sensitive surfaces, and it should allow greater post spacing than before when designing the walls due to its higher bending stiffness.

These and other objects not listed in detail are achieved in a transparent pane element of the type mentioned at the outset by the features of the characterizing part of claim 1.

Advantageous embodiments are the subject of the dependent claims.

Because the pane element is designed as a composite pane with a plastic pane as the core, which is arranged between two panes of inorganic glass, it is possible to provide a composite material that has all the advantages of the known elements, in particular the advantage of splinter binding in the event of breakage, and which, in addition, under the conditions of use

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is practically non-flammable, has a higher rigidity, especially bending stiffness, compared to noise protection elements of the same thickness made only from plastic and thanks to the surfaces with increased scratch resistance, is easy and inexpensive to clean even by machine.

The plastic panes embedded between two panes of inorganic glass are known per se. The plastic that serves as a "matrix" for the thread-like elements is a thermoplastic, which is preferably amorphous and furthermore preferably has a coefficient of thermal expansion that is approximately the same or lower than the plastic of the internal plastic threads, bands, grids or nets, which can be amorphous, partially crystalline or crystalline.

Preferably, the inner plastic (thread-like elements) has a higher elongation at break, a higher shear stability and a higher viscosity than the matrix plastic.

Examples of amorphous plastics A or B are: polyvinyl esters, polyvinyl ethers, amorphous polyvinyl halides, polystyrenes, polyphenylene oxides, polyphenylene sulfides, polycarbonates, polysulfones, amorphous polyamides, polyether ketones, polyether ether ketones, polyether sulfones, polyimides, polyetherimides, polyfluoroalkenes, polyester carbonates, amorphous polyolefins and very particularly preferably poly(meth)acrylates. Examples of the crystalline or partially crystalline plastics B are polymers in which the crystallinity is determined by a uniform tacticity or sufficiently small 0 substituents so that a crystal lattice can form at least partially. Examples include polyesters, crystalline polyolefins, crystalline polyvinyl halides, liquid crystalline polymers with mesogenic groups in the main and/or side chain, or particularly preferably crystalline polyamides. For the production

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and characterization of plastics A and B, see for example Kirk-Othmer, Encyclopedia of Chemical Technology, 3rd Ed. Vol. 18, pages 720 to 755, Wiley Interscience, 1982.

The production of such plastic sheets can be done in any way familiar to the expert.

In a preferred embodiment, the plastic disc as the core of the composite disc is obtained by a discontinuous casting process.

One way to do this is to form a chamber using two prefabricated cast plastic plates, e.g. acrylic glass plates (2000 mm x 1220 mm x 8 mm) with the help of a 4 mm thick circumferential seal. Monofilament plastic threads, ζ. β. polyamide threads, with a diameter of 0.9 mm are then clamped into this chamber approximately in the middle at a distance of 30 mm parallel to each other. A low-viscosity, cold-curing methacrylate resin containing an external plasticizer based on a citric acid ester and a redox initiator system 0 is then filled into the chamber.

Once the intermediate layer has completely hardened, a plastic pane is obtained that is suitable as the core of the composite pane.

Alternatively, it is also particularly advantageous to produce the plastic pane as the core of the composite pane according to the invention by continuous coextrusion of two incompatible thermoplastics.

Preferably, the plastic is fed into a coextrusion nozzle at the feed points and then distributed to the desired product width in two 0 separate distribution channels. Between the distribution channels for the plastic, the plastic to be embedded is fed into a transverse distribution bore at the feed point.

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The plastic to be embedded leaves the cross-distribution bore through a larger number of holes, which corresponds to the number of segments of this material in the matrix.

Where the plastic to be embedded emerges from the holes, the two layers of the matrix plastic are brought together and thus enclose the strands of the plastic to be embedded.

The cross-sectional shape of the plastics to be embedded in the matrix depends essentially on the design of the holes in the outlet area and the ratio of the viscosities of the matrix plastic and the plastic to be embedded. If the viscosity of the plastic to be embedded is greater than the viscosity of the matrix, the segments will be more round in cross-section, while if the viscosity ratio is reversed, they will be more flat.

After leaving the nozzle, the composite can be calibrated in a conventional polishing unit. Since the plastic to be embedded is enclosed in the matrix plastic, it can only cool down relatively slowly. With a semi-crystalline or crystalline plastic to be embedded, significantly higher degrees of crystallinity are achieved than with conventional extrusion of the strands of the material to be embedded.

If a periodic change in the cross-section of the segments of the material to be embedded is desired over the length, this can be achieved in a simple way by periodically changing the mass flow fed in at that point. Since the plastic to be embedded has a higher thermal expansion than the matrix plastic, in conjunction with the form fit between the two plastics, a pre-stress of the segments of the plastic to be embedded is achieved (comparable to

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reinforced concrete). This allows a further increase in the mechanical properties of the composite.

The plastic threads embedded inside the plastic disc of the composite can be arranged so that they run parallel to each other in only one direction, or so that they run parallel to each other in two directions. In the latter case, the two directions can form an angle of 90° or an angle other than 90°. If plastic strips are embedded, they are expediently arranged so that they run parallel to each other in only one direction.

In a special design, the internal plastic threads are high-contrast and therefore have a bird protection effect.

High-contrast plastic threads are those with a transmission level of the plastic used for production between 0 and 65% (measured according to DIN 5033 color measurement and 5036 radiation-physical and light-technical properties of materials). The material or the plastic thread itself preferably has a transmission level of 0 to 30%, especially 0 to 10%. A transmission level of around 0% is particularly good. Dark-colored threads, especially black threads, are advantageous. Thanks to their high-contrast threads, flying birds can recognize such a transparent wall as an obstacle from a few meters away and can fly around the plastic wall accordingly.

0 Designs in which the plastic threads are 1 mm to 5 mm thick are particularly advantageous. In particular, the thickness range of 1.8 mm to 3.0 mm, preferably 2.0 mm to 2.5 mm, has proven to be the most suitable in terms of the required properties, easy insertion into the

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Plastic pane, sufficient strength in the event of breakage, sufficient bird protection effect and no significant impairment of the overall transparency of the pane have proven to be particularly advantageous.

The threads in the plastic disc usually run horizontally, as the discs are clamped laterally; the cohesion in the event of a break is then particularly good. The threads are usually laid parallel to each other. If desired or necessary, two layers of threads can be inserted into the disc, which then preferably run in two directions, with an angle of 90° between threads in different layers being particularly advantageous. Such a design looks like a mesh fabric when viewed from the outside.

As a rule, a maximum distance of 100 mm between adjacent threads is chosen; above this, the effectiveness of bird protection or securing fragments is significantly reduced. A thread distance of up to 50 mm is preferably chosen, especially if the threads run horizontally, as birds are presumably less able to detect horizontal obstacles than vertical ones.

The surface density of the high-contrast threads, i.e. the percentage of the area covered by the threads in the entire plastic pane, usually ranges from 2.5 to 25%. Preferably, especially with horizontal threads, the surface density is at least 5%, with 6 to 10% being particularly advantageous. With vertically laid threads, a slightly lower surface density is sufficient, so that the advantageous range here is 5 to 8%. Below this surface density, the bird protection effect is quickly lost; above these values, the threads remain visible even at a greater distance and have a correspondingly unaesthetic effect, i.e. the advantageous effect of the transparency of the plastic pane 5 is largely lost.

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Typical disk thicknesses are 5 to 40 ram, with 12 to 25 mm being preferred. The disks are usually manufactured in sizes from 1.5 m x 1 m to 2 m x 3 m, and larger or smaller versions are also possible for special applications.

The panes are usually largely transparent, preferably colorless or slightly tinted, e.g. smoky brown. The colorless, crystal-clear plastic panes usually have a transmittance of at least 70%, with a transmission of 90 to 95% being advantageous. Tinted versions usually have a transmittance of 45 to 75%, usually between 50 and 60%. The absorption of the threads and the tinted pane is added together, so that the threads can still be recognized as high-contrast elements.

The essential characteristic of the invention is that the plastic pane described is arranged as the core of the composite pane between two panes of inorganic glass.

Although the inorganic glass material itself is not subject to any particular restrictions, those embodiments are preferred in which sufficient and high adhesion can be achieved between the glass panes and the plastic pane core.

What was particularly surprising was that it was possible to design the bond between preferably inorganic float glass or even single-pane safety glass on the one hand and a plastic pane core on the other in such a way that the splinter-binding effect of the core in the event of breakage is also extended to the glass components of the composite. In other words, if the entire structure breaks, this prevents glass components of the panes made of inorganic glass from flying around.

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This also prevents any splinter releases from the plastic disc core.

A whole range of glasses are regularly considered as composite partners for the composite panes according to the invention with a plastic pane core. The inorganic glasses that can be used include float glass and mirror glass, both preferably hardened as single-pane safety glass.

Of the aforementioned types of glass, float glass is preferred as toughened safety glass.

All methods familiar to the person skilled in the art can be used to produce the structures according to the invention. On the one hand, it is possible to laminate the panes of inorganic glass onto prefabricated plastic pane elements. This is then preferably done with adhesion promoters, which are also used, for example, in the process known to the person skilled in the art for producing laminated safety glass made of inorganic glass. The preferred procedure is to first clean the glass panes thoroughly. The same applies to the plastic pane core. One or more plastic intermediate layers (e.g. film made of polyvinyl butyrol) are then placed between the plastic core and the glass pane. The structure is then pressed together in a rolling process to connect it.

The pressed combination is then placed in an autoclave, where the glass and intermediate layers as well as the plastic core disc are firmly bonded together using heat and pressure. The resulting disc element is very strong and has a clear, undistorted view.

On the other hand, sufficient adhesion can also be achieved during the casting process, for example, by polymerizing the inner plastic pane between the glass panes and in contact with them.

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If necessary, suitable substances are added to the mixture to be polymerized to increase adhesion, e.g. organosilanes.

Alternatively, it is also possible to place corresponding glass panes while they are still warm on the plastic core panes produced by coextrusion, which have not yet completely cooled down, whereby sufficient adhesion can be achieved even without the addition of an adhesion promoter.

Overall, both symmetrical and asymmetrical structures are conceivable according to the invention. This means that in a symmetrical structure, two identical panes of inorganic glass contain a plastic pane core. If the structure is asymmetrical, this means that two panes of inorganic glass, the two panes of inorganic glass being made of different materials, together with a plastic pane core form a composite according to the invention. This makes it possible, for example, to adapt the design of the composite according to the invention to specific requirements. For example, a single-pane safety glass panel can be provided on the side of the noise barrier facing the road or rail due to the required stone chip resistance, while cheaper glazing with, for example, float glass can be considered on the back.

The composite panes according to the invention are used in particular for fireproof, rigid noise barriers with a scratch-resistant surface. In this case, it is also particularly preferred to design the inner plastic core in such a way that the composite according to the invention can also serve as a bird protection element.

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In the following, the invention is explained in more detail using embodiments with reference to the attached figures.

In the figures show

Figure 1 is a perspective, partially cut-away view of a first embodiment of the inventive pane element, with concealed details partially indicated by dashed lines;

Figure 2 is a perspective, partially cut-away view of a second embodiment of the pane element according to the invention, with hidden details partially indicated by dashed lines;

Figure 3 is a perspective, partially cut-away view of a third embodiment of the pane element according to the invention, with hidden details partially indicated by dashed lines;

0 Figure 4 is a perspective, partially cut-away view of a fourth embodiment of the inventive pane element, with concealed details partially indicated by dashed lines; and

Figure 5 is a perspective, partially cut-away view of a fifth embodiment of the pane element according to the invention, with hidden details partially indicated by dashed lines.

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In Figures 1 to 5, 1 designates a fire-safe, transparent pane element according to the invention. As can be seen in all figures, it has a plastic pane 5 as its core, which is embedded between two glass panes 3 and 4 and forms a composite pane 1 with them. The glass panes 3 and 4 can be made of different or the same material. Threadlike or flat plastic structures 2 are embedded in the plastic core element 5.

Figure 1 shows filamentary plastic layers 2 obtained by coextrusion, which are arranged in the plastic disc core 5 during the production of the latter. In Figure 5, plastic strips 2 are embedded in the core 5 by a casting process. Figure 2 shows the design of the inserted elements 2 as threads that extend parallel to one another, while Figure 3 illustrates a case in which the threads 2 cross to form a grid, with the longitudinal threads being essentially parallel to one another, as is the case for the threads 2 running transversely to them at an angle of approximately 90°. The threads 2 can be arranged in two planes, so that the longitudinal threads run above or below the transverse threads. However, the longitudinal threads can also alternatively be arranged above and below the threads running transversely to them.

Finally, Figure 4 shows the use of a net-like structure 6 as thread element 2.

Disc elements according to the invention can be manufactured, for example, as follows:

Two panes measuring 3000 x 2000 x 8 mm made of ESG (single-pane safety glass) are spaced apart using a circumferential seal so that a gap of 4 mm is created between the panes. In this cavity, black, 2 mm thick polyamide threads are inserted at a distance of

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3 0 mm parallel in the longitudinal direction (edge length 3000 mm). The threads were fixed to the surrounding seal for precise positioning before the two glass plates were joined together.

The cavity between the panes is now filled through an opening in the seal with a low-viscosity, colorless composite resin based on MMA and various acrylate and methacrylate comonomers, e.g. Degalan SSSS or S700. The polymerization of the cold-curing composite resin was started shortly beforehand by adding hardeners and accelerators based on organic peroxides and organosilane compounds as adhesion promoters.

The discs were placed at a slight angle for filling. Polymerization, which is completed after about 1.5 hours, takes place with the plates arranged horizontally.

Claims (11)

Degussa Aktiengesellschaft .1 #"« ;**;·": ;*%5*0&rgr;%7 PO / GM 60311 Frankfurt : '"I * \ I .' * *'*· ' 16 1. Fireproof, transparent pane element with a plastic pane with internal plastic threads, bands, grids or plastic nets, which largely hold together any fragments that arise in the event of breakage, characterized in that the pane element (1) is designed as a composite pane with a plastic pane (5) as the core, which is arranged between two panes (3, 4) made of inorganic glass. 2. Disc element according to claim 1, characterized in that the plastic disc (5) as the core of the composite disc (1) is obtainable by a discontinuous casting process. 3. Disc element according to claim 1, characterized in that the plastic disc (5) as the core of the composite disc (1) is obtainable by continuous coextrusion of two incompatible thermoplastics. 4. Disc element according to one or more of the preceding claims, characterized in that internal plastic threads (2) have a diameter of between 1 and 5 mm and that the distance between the threads is at most 100 mm and the surface density of the threads is between 2.5 and 25%. Degussa Aktiengesellschaft ·· ·**· ;* J · ; ; 350J767 PO / GM 60311 Frankfurt 5 "·:*::.'· *'* \ 5. Disc element according to claim 4, characterized in that the thickness of the inner plastic disc (5) is in the range 4 to 40 mm. 6. Disc element according to one of the preceding claims, characterized in that the plastic threads (2) are monofilament threads made of polyamide or polypropylene. 7. Disc element according to one of the preceding claims, characterized in that the threads (2, 6) are high-contrast and have a transmittance of the plastic used for the production of the threads of 0 - 65%. 8. Disc element according to one of the preceding claims, characterized in that the material of the plastic pane (5) is acrylic glass with embedded polyamide threads (2). 9. Disc element according to one or more of the preceding claims, characterized in that the core (5) is arranged between two panes (3, 4) made of the same inorganic glass. 10. Pane element according to claim 9, characterized in that the inorganic glass is float glass or single-pane safety glass. Degussa Aktiengesellschaft ,1 ."* ·"··"*· :*9£0*Q67 PO / GM 60311 Frankfurt \ "·*· *· I .··"·· 11. Disc element according to one or more of claims 1 to 8, characterized in that the core (5) is arranged between two discs (3, 4) made of different materials.