DE7404313U - Press pad in the form of a metal fiber fleece - Google Patents

Description

Th. Goldschir. idt AG, Essen

Press pad in the form of a metal fiber fleece

The invention relates to a press pad in the form of a metal fiber fleece special design.

It is known that when pressing carrier webs or curable foils impregnated with curable synthetic resins onto wood-based panels, preferably in hydraulic hot presses, press cushions are used. Pressure equalization can be used. The press pad is located between the heating plate of the press and the press plate, which impresses the surface structure of the plate to be tempered. The press pad serves to equalize pressure and temperature during the pressing process and prevents wear and tear on the high-quality press plate. Pressure differences are caused by unevenness in the heating plate, _r The press pad in the press plate and / or in the pressing material itself. Which are used in multi-tier or eiuetagigen presses, are preferably made of cotton and / or asbestos fabrics. These pads have a good pressure equalizing effect. However, their low thermal conductivity is a disadvantage.

When coating, the material to be pressed, e.g. the material to be coated, is applied Chipboard, heat dissipated, which is tracked from the heating plate via the press poister and the press sheet must become. As a result of the low thermal conductivity of the cotton asbestos fabric cushion, the temperature on the press plate drops because not as much heat can be added as is absorbed by the pressed material.

Metal mesh has also been used to equalize pressure. puts. These have better thermal conductivity, but inadequate cushioning effect.

When using cotton asbestos fabrics as a press pad, it is therefore necessary that relatively long press times or higher temperatures of the hot press must be provided in order to ensure proper curing of the synthetic resin reach. The temperature of the hot press is preferably increased in order to achieve as many pressing cycles as possible. This is true especially when pressing in one-story ;; 'short cycle i press to. However, the temperature increases are relatively limited.

The so-called short-cycle method has recently been gaining ground; iipmer greater importance. The hardening of the synthetic resin surfaces takes place in a continuously hot single-daylight press

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carried out, whereas the cooling of the pressed material outside the press takes place. Press plates and press pads are therefore firmly inntnt in the press.

To carry out the short-cycle process, wood-based panels and the synthetic resin films are placed on the loading device merged. By means of a belt tray, the material to be pressed is fed into the hot press and deposited there, whereupon the tape tray returns to its starting position. Immediately afterwards the press closes and that Synthetic resin hardens under heat and pressure. After the curing time has ended, the press is opened and the hot one Prefabricated panel moved out of the press with a transport device.

If the press plate temperatures are too high, the synthetic resin film condenses on the lower hot one when the press is loaded Press plate prematurely without pressure, so that defective surfaces arise.

From the Belgian patent specification 801 220 is a method for pressing on impregnated with curable synthetic resins Carrier sheets or curable plastic films on the surface of wood-based panels in heating presses, whereby A press pad is inserted between the press tool and press plate, known, which is characterized in that

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a compressible metal fiber fleece is used as a press pad which at least approximately approximates the original pre-poister thickness after the pressure has been relieved.

The mechanical stress on the metal fiber in the metal fiber fleece is considerable due to the constant load change. In addition, these burdens and reliefs of the Metal fiber fleece at temperatures of 120 to 190 C. This leads to the fact that individual metal fibers in places break special stress, so that the service life of such a metal fiber fleece as a press pad in a Hot press is sufficient, but limited.

From US Pat. No. 2,372,114 it is known to use metal fiber fleeces as padding for flat sheet metal shells as a press pad in high-pressure presses for the production of laminates to be used, whereby the flat sheet metal sleeves are welded together on all sides. This only achieves that the mechanical stress of the Fiber fragments or particles produced by the press pad remain in the metal fiber fleece. A destruction of the However, this does not prevent metal fiber fleece. Such an enclosing of the metal fiber fleece is also for the intended use disadvantageous, because just the The fact that the metal fiber fleece should be open on all sides and allow air to enter and exit, thereby

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is prevented. However, when the metal fiber fleece is used as a press pad in so-called short-cycle presses "On GntSCiieicLencieir Bcclc ¹ ^""!" ¹ ^ - ^ "Hf = I iifiy P.ückffidpruno di ^ s elastic metal fiber fleece after pressure relief can flow into the metal fiber fleece from the sides, it can cool down and interrupt the heat flow. Communication with the outside air is therefore of crucial importance for the purpose .

The invention is based on the object of providing a press pad on the basis of a metal fiber fleece with the aforementioned properties to develop, - which is in particular through is characterized by a longer service life, i.e. in which the susceptibility to breakage of the individual fibers is significantly reduced when changing pressure loading and unloading.

Surprisingly, it has been found that these properties a metal fiber fleece, whose individual fibers with are coated with a hardened synthetic resin.

Subject invention thus relates to a press pad in the form of an open on all sides, air inlet and outlet permitting compressible _r elastic metal non-woven fabric whose fibers are coated with a cured synthetic resin.

The press pad according to the invention can be produced in such a way that the metal fiber fleece is mixed with the solution

a curable synthetic resin soaks and the solvent
evaporates. Only such amounts of resin are allowed into the
Metal fiber fleece can be introduced so that, although the individual fibers are enveloped, the pores formed by the fibers
but remain open in the fleece. The corresponding amount of synthetic resins to be used thus essentially depends
according to the fiber diameter and the structure of the metal fibers used to produce the metal fiber webs. the
Curing can either be carried out after the evaporation of the solvent by means of heat or else
take place under operating conditions in the press.

Another type of manufacture is that one is in front of
During the formation of the fleece, the fibers or fiber strands intended for the production of the fleece are treated in the aforementioned manner and then the fleece is formed from the resin-coated fibers.

In principle, all are suitable as curable synthetic resins
Synthetic resins adhering to metals. From this it follows that primarily those synthetic resins are particularly suitable which are known from the technology of metal bonding. Phenol-formaldehyde resins, which are optionally etherified and / or, for example, with others, are particularly useful
Synthetic resins such as polyvinyl acetate may be modified
can. Epoxy resins, such as those generally used for metal bonding, are also suitable. These too

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Epoxy resins can be used together with other synthetic resins, both condensation resins of the type Phenol-formaldehyde resins as well as derivatives of polyvinyl alcohol such as polyvinyl butyral can be used.

The press pads according to the invention should preferably be in _;

Hot presses, especially so-called short-cycle presses, for j

the remuneration of the surfaces of wood-based panels by I curable synthetic resin films can be used.

A press pad according to the invention is shown in the attached Figure shown. The individual fibers forming the fleece are denoted by (1). The individual fibers are surrounded by a synthetic resin film (2), but the pores (3) between the fibers remain open to allow them to be pressed together of the fiber fleece a compression of the fleece with an outflow of air and, after the pressure has been released, a spring back of the metal fiber fleece according to the invention at the same time Allow air to flow in.

Claims (1)

Claim to protection Press pad for hot pressing in the form of an all-round open, Compressible, { elastic metal fiber fleece, the fibers of which with a