DE3147123A1 - Finished or semi-finished product of plastic having a thermotechnical or electrotechnical function and process for its production - Google Patents

Description

3147-23

Finished or semi-finished products made of plastic with a thermal or electrical function and Process for its manufacture

DESCRIPTION

The invention relates to finished or semi-finished plastic products, in particular made of high-density polyethylene (HDPE) with heat-

technical or electrotechnical function.

In thermal engineering, there is a strong, still increasing need for heat exchangers of all types. In particular shell-and-tube heat exchangers become more closed and open

Design for liquid-liquid heat exchange due to its advantages and its almost universal applicability (cf. VDI-Wärmeatlas 1953-Pa · 1) to a large extent in the chemical and pharmaceutical industries.

^ But you also need in many other industrial areas / i.e. wherever indirect cooling or heating processes take place, effective heat exchangers, especially tube bundle heat exchangers. A new area of application for the latter has arisen in the heating industry. Always need more heat pumps than heat collectors, especially in private residential construction

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Pipe systems, either as water-water, air-water! · or ground-water heat exchangers are designed.

When choosing the material for the pipes such Corrosion resistance plays a decisive role in heat exchangers. With regard to heat conduction, the materials are Copper and aluminum, while ideal, are only opposed to a limited number of media, primarily in the chemical industry for heat exchange in question, corrosion-resistant. Compared to a larger number On the other hand, chromium-nickel steels (V4A quality) are corrosion-resistant from other media, which is why they are also used for Have become the standard material for the chemical industry. However, even for extreme corrosive loads

■ J5 no longer offers these materials. In such cases come Steels alloyed with titanium are used, or glass tube bundle heat exchangers are used up to certain pressure values. When selecting the suitable pipe materials, the price is less important (chromium-nickel steels and even more so with titanium alloyed steels are very expensive materials) rather than the properties of the materials play a decisive role. In addition to corrosion resistance, it is primarily the thermal conductivity that is important, which is known to be associated with the Heat transfer coefficients decisively determine the heat transfer and thus the conductivity of the heat exchanger.

The thermal conductivity values Xt of the materials used for tube bundles of heat exchangers are, for example, as follows:

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^ -O ⁰ C Kcal / mhK

Copper (pure) 330 Aluminum (pure) 200

CrNi steel
TiCrNi steel
10 glass

Polyethylene
high density
(HDPE)

14th

10

1.15
0/44

150 ⁰ C
Kcal / mhK

λ-

0.265

300 ⁰ C Kcal / mhK

320 200 16 10 1/4 0.265

You can see that you are using glass tubes for corrosion resistance in the widest possible range and a considerably lower price for semi-finished products has an extremely low thermal conductivity.

If tubes made of high-density polyethylene (HDPE) were used for tube bundle heat exchangers, they would have The following properties compared to glass tubes:

The decisive disadvantage, as the table shows, is the even lower thermal conductivity. Advantages of. HDPE pipes are certainly the even lower pipe price due to material and production technology, the more universal usability both in terms of corrosion resistance and in terms of the working areas (HDPE pressure pipes can be produced up to 64 bar) and the better processability (HDPE pipes can be bent, with each other and in HDPE floors are welded or welded in, ie no sleeves and mechanical seals are necessary). Furthermore, HDPE pipe bundles can also be used

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Equip with HDPE lamellas by welding, what for the improvement of the heat exchange properties is beneficial is, because fins increase the heat transfer to the pipe as is well known (cf. VDI-Wärmeatlas 1963 Mb 1). HDPE pipes would therefore be an ideal starting semifinished product for tube bundle heat exchangers / if they are a considerably better one Would have thermal conductivity.

The invention is based on the object of the thermal or electrical functions of plastic, especially of HDPE.

The subject of the invention is thus a finished or semi-finished product Made of plastic, especially high-density polyethylene (HDPE) with thermal or electrical engineering Function which is characterized in that the plastic conducts heat or electricity Filler, preferably a metal powder or granulate in one to improve the thermal conductivity or the electrical conductivity contains sufficient quantity.

The finished or semi-finished product according to the invention lies in particular in the form of plate or tubular heat exchange elements / such as tubes for tube bundle or plate profiles for plate heat exchangers.

A metal with high thermal conductivity is preferably used as the filler, in particular copper and / or aluminum powder or granulate is used. Depending on the requirement the proportion (concentration) of the metal powder in the plastic is between 1 and 50% by volume.

The thermal conductivity of the finished or semi-finished product doped with the filler increases with the percentage Proportion of the filler added. However, with increasing filler concentration, the aging resistance decreases

* - SI

and certain mechanical properties of the plastic deteriorate, such as fatigue strength. However, since Even small amounts of conductive filler additives are sufficient to considerably increase the thermal conductivity / · The remaining fatigue strength properties are completely sufficient for the applications in question.

Basically any thermoplastic or thermosetting plastic can be used, provided it is lumpy or endless Can process finished products or semi-finished products with a thermal function, loaded with the thermally conductive filler or be endowed.

As already mentioned, the finished or semi-finished product according to the invention has not only a thermal, but also a, electrotechnical function. It is well known that all plastics are more or less good electrical insulating materials. The finished or semi-finished product doped with the conductive fillers according to the invention, however, also has an electrical one Conductivity, which in turn is essentially a function of the concentration of the metallic filler particles. Both thermoplastic and thermosetting · / Plastics are doped with the electrically conductive fillers.

By doping the plastic with metal powder, an electrically semiconducting material is obtained, which can be used, for example, as a outer covering layer attached to electrical cables, causes a shielding effect.

Regarding the applicable manufacturing processes and devices In principle, there is no restriction, i.e. all processes and devices for the production of thermoplastic or thermosetting plastic finished or semi-finished products are used for doping with the conductive filler powders or granules.

The subject of the invention is therefore very generally also a Process for the production of finished or semi-finished plastic products, which is characterized in that the Plastic with a material that conducts heat or electricity Filler, preferably a metal powder or granulate in one to improve the thermal conductivity or the electrical conductivity doped sufficient amount and the doped plastic to finished or Shapes semi-finished products.

-.

Particularly suitable processes for the preparation of the invention Finished or semi-finished products include screw molding (extrusion) and injection molding. The doping of the Mixtures of substances with metal powder processed according to these methods and also corresponding devices, preferably copper and / or aluminum powder or granulate, can be done in the following way:

One mixes plastic powder as the main component of the too processing ϊ mixture of substances in batches with metal powder and, if necessary, further additives to the finished product

Mixture of substances and then continuously doses it in the feed zone of an extruder or a screw conveyor of an injection molding machine. Mixing is preferred the plastic powder is carried out with the metal powder in a high-speed mixer.

But you can also use free-flowing metal powder with all of them other components of the mixture in a stationary small-component mixer above a screw feed zone meter in continuously, mix there and the mixture of substances into the feed zone an extruder or a screw conveyor of an injection molding machine support financially.

You can also use a mixture of plastic and metal powder via a metering screw as an agglomerate into the agglomeration

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zone of the main extruder or an injection molding screw continuously metering in and the agglomerated mixture there with the agglomerate of undoped and if necessary, mix plastic containing further additives (so-called double or tandem extrusion).

Claims (9)

R. SPLANEMANN. dipu-chem. dr. B. REITZNER ZUQEL. REPRESENTATIVE AT THE EPO HKPRKSKNTATIVKS BKPORK EPO ■ MANOATAIRES AQRKES PRtS L'OKB Cable and rubber plants eooo munchen a November 27, 1981 Stock company abbreviated: ™ £ _(M " _{H 6707/22} " _w Kabelwerk EUpen Telegrams: Invenliu · Münditn Manufactures de Cables τ.ι «: s2B4iein» uid Electriques et de Caoutchouc Societe Anonyme, en abrege:, «,, tu "Cäblerie d'Eupen" ^Un " ^r - ^Ak ·· '2937-1-11. B-4700 Eupen ^lhrM * - ' Patent application Finished or semi-finished products made of plastic with a thermal or electrical function and Process for its manufacture. PATENT CLAIMS Finished or semi-finished products made of plastic, in particular made of High-density polyethylene (HDPE) with a thermal or electrical function, characterized in that the plastic a heat or electricity conductive filler, preferably a metal powder or -granulate in an amount sufficient to improve the thermal conductivity or the electrical conductivity contains. 2. Finished or semi-finished product according to claim 1 in the form of plate-shaped or tubular heat exchange elements, such as Tubes, rods, ribs or plate profiles for heat ' exchangers or collectors. 3. Finished or semi-finished product according to claim 1 or 2, characterized characterized in that it contains copper and / or aluminum powder or granulate as filler. Accounts: Oautich · Bank AG. MOndwn. KofltteNr. »14 009 · *»! ». *« *. MüB «fc · - 4. Finished or semi-finished product according to claims 1 to 3, characterized in that, depending on the requirements placed on the product, the proportion of metal powder in the plastic is between 1 to 50 vol .-%.
5 5. Process for the production of finished or semi-finished products made of plastic according to one of claims 1 to 4, characterized characterized in that the plastic with a heat or electricity conductive filler, preferably a metal powder or granulate in one to improve the thermal conductivity or the electrical conductivity doped sufficient amount and formed the doped plastic into finished or semi-finished products. 6. The method according to claim 5, characterized in that the filler is copper and / or aluminum powder or -granulate adds. 7. The method according to claim 5 or 6, characterized in that plastic powder is used as the main component of the processing substance mixture in batches with metal powder and, if necessary, further additives to the finished substance mixture mixed and this is then continuously fed into the feed zone of an extruder or a screw conveyor metered into an injection molding device. 8. The method according to claim 7, characterized in that the mixing of the plastic powder with the metal powder in a large capacity high-speed mixer. 9. The method according to claim 5 or 6, characterized in that one free-flowing metal powder with all the others Components of the mixture of substances in a small-component mixer arranged stationary above a screw feed zone continuously dosed, mixed there and the mixture of substances in the feed zone of an extruder or a screw conveyor of an injection molding device promotes. -γ *. ^: -. ^: .:. 3Η7123 3 10, method according to claim 5 or 6, characterized in that a mixture of plastic and metal powder is continuously metered into the agglomerating zone of the main extruder or an injection molding device via a metering screw as an agglomerate and there it is with the agglomerate of undoped _y possibly containing further additives Plastic mixed.