ES2314800T3 - PRESSURE COMPENSATION FABRIC FOR HOT PRESSED HYDRAULIC FACILITIES. - Google Patents

Abstract

Woven pressure padding for hydraulic hot presses comprises metal threads with heat-resistant elastomer threads incorporated in such a way as to form the first contact points on the surface, thus reducing heat flow from the heating plate to the pressure plate until they are compressed under increasing pressure, enabling rapid heat transfer via metal contact points. Pressure-compensating woven fabric (6), especially pressure padding for use in hydraulic hot-press systems, comprising high temperature-resistant elastomer threads (3) (with or without stabilising metallic or non-metallic core threads (4)) and metal threads (1). In this fabric, the elastomer weft threads (3) or warp threads are threaded through the metal warp threads (1) or weft threads and the alternating metal weft threads (1) or warp threads in such a way that the upper points of contact on the padding are formed by elastomer threads, resulting in a reduced heat flow from the heating plate to the pressure plate when used in a press; the elastomer threads (3) are only compressed when the applied pressure is increased, so that the metal threads (1) then form the thermal contact and heat is rapidly transferred from the heating plate to the pressure plate.

Description

Pressure compensation fabric for hydraulic hot pressing installations.

The present invention relates to a fabric of pressure compensation, in particular, a compression padding, suitable for use in hydraulic pressing installations in hot, comprising some metallic threads, both in the form of warp threads as in the form of weft threads of the padding of compression, and high resistant elastomeric threads temperatures, the latter preferably with soul threads stabilizers, the elastomeric threads being arranged in shape of warp threads or in the form of weft threads alternating with The metallic threads.

Compression mattresses are used in different types of pressing installations such as, for For example, the so-called short-plane single plane presses for lining chip plates, medium density fiber plates (MDF) or high density fiber (HDF) plates with resins Duroplastics, such as melamine resins, mixed resins of melamine urea or phenol resins, but also in high and low pressure multi-plane presses for manufacture of high pressure laminated plates, compact plates and Plywood plates. In principle, the mattresses of Compression can be used in all pressing installations. Compression mattresses of this type are formed, so general, in the form of fabric, the materials being resistant to high temperatures, since the operating temperatures in Pressing facilities are partly higher than 200ºC. In addition, they should present, if possible, a great capacity for replacement in case of an intermittent compression load and They should have rapid thermal conductivity.

When forming surfaces in plate materials previously indicated, duroplastic resins are very sensitive to pressure tolerances. In this way, defects can form superficial by an irregular distribution of pressure. Is known that in coating installations there are tolerances of considerable thicknesses, which add up between the pressing system, pressure plates and the product that is going to be pressed, respectively. Compression mattresses have, therefore, the goal of balancing these tolerances of thicknesses and transmit the pressing force on a regular basis and on the entire surface to the product to be pressed, intended achieve a fast and regular heat transmission at the same time of the hot plate temperature of the pressing system to the product to be pressed.

For example, compression mattresses are known generic by DE 90 17 587 U1. Quilting fabric flexible is formed by a thread of aromatic polyamide, which is optionally mixed with other thread materials. The tissue Textile contains some metallic threads, the proportion between 0 and 70% by weight to adjust correspondingly the required thermal conductivity.

EP 0 713 762 A2 discloses a compression padding for high and low pressure presses different materials

In EP 0 735 949 B1 it is also described a compression padding known for the state of the technique, presenting the warp and / or weft threads a silicone elastomer and a thread being contained in the fabric metallic in the form of solid threads or threads provided with a silicone coating

In addition, document DE 200 08 249 and the EP 1 136 248 B1 discloses a compression padding formed by a tissue that has a significant percentage of a mixed elastomer, which has been manufactured by crosslinking a silicone rubber and a fluorinated rubber or a silicone rubber and a fluorinated silicone rubber. The percentage of fluorinated rubber or of fluorinated silicone rubber should be at least 4% in weight, preferably 10% by weight. The warp and / or threads of Weft contain metallic threads.

In addition, EP 0 978 528 A1 gives know a compression padding that is used for the manufacture of printed circuit boards. The padding already known can present a tissue, a paper, a film or a leaf-like structure, which is combined respectively as layer with at least one other layer of a fluorinated elastomer. He Fluorinated elastomer should preferably have a component of fluorinated rubber of the polyol vulcanization system, an agent of vulcanization, a vulcanization accelerator, as well as an acceptor of acid.

Another compression padding is described in the EP 1 300 235 B1. In this case, it is a fabric metallic, formed by warp threads with lining stainless steel and twisted copper wires with aramid core, being provided the metallic fabric of a rubber lining of silicone. To ensure heat transmission, the threads of Copper protrude from the surface of silicone rubber.

It is also worth mentioning document DE 297 21 495 U1, for which a compression padding is known for its use in rolling presses with a fabric that has two groups of threads that extend in parallel, respectively, crossing the threads of the first and second group. The threads of first group are made from metal or present at minus a part of metal, and the threads of the second group are made from an elastic material, such as rubber or They have at least a part of it. To create a padding Compression with better thermal conductivity, the density of the threads of the second group is so large that the threads of the first group only go through the threads of the second group in state compressed. Since, due to the reduced distance between threads of the second group, the threads of the first group are forced to pass very inclined between these threads, occur short paths between the two padding surfaces of compression, so that the heating of the product that is going to Pressing is done faster.

In EP 1 386 723 A2, it is described a compression padding according to the preamble of the claim 1, whose types of threads contain a polymer material, respectively, having to present the types of elastic threads different, respectively, in the transverse direction with respect to its axis In a preferred embodiment, the types of threads they must present a soul of metallic threads to guarantee the resistance of polymer threads in the longitudinal direction.

Finally, document DE 200 11 030 U1 gives know a compression padding in your thread system It has heating wires for active heating of the compression padding, these wires being integrated into Fabric technique matter in the quilting structure of compression.

For modern coating technology, as it currently takes place, for example, in single-plane presses of short cycles, the indicated compression mattresses have deficiencies in their physical structure.

In particular, in the plating of Highly sensitive fiber (High Density Fiberboard) with a superimposed layer of a melamine resin and filled with Al 2 O 3 and a decorative film of melamine resin for the manufacture of floor covering plates requires about extremely strict compression padding requirements of so that, in case of a heat transmission not adapted from the hot plate to the pressure plate defects occur surface in condensed melamine resins. Since currently they are intended to achieve more pressing times reduced, the flow of the resin must be controlled, despite this, such that the formaldehyde and water vapor that forms in the condensation of the resin can diffuse with sufficient speed in the paper strip and the plate surface.

During the coating on the press, the melamine resins are, first of all, fuses with low viscosity and fluidity, subsequently crosslinking to form insoluble, hard and infusible, abrasion resistant plastics as well as resistant to high temperatures. In this case, we talk about the so-called polycondensation in which water is formed and formaldehyde. Water and formaldehyde that forms during Condensation reaction cannot be released in the form of steam, since the press force existing in the press is by above the water vapor pressure, introducing the two gaseous products also under pressure in the film layer or in the support plate The flow time and melting viscosity of the resin is determined substantially by the degree of condensation, reaction capacity and temperature and should be adapted so that the vapor bubbles can come out before solidifying the resin melt and forming the surface. If these vapor bubbles cannot spread sufficiently on the support plate, surfaces are formed that They can be between cloudy and milky. This cloudiness is caused by the different indexes of refraction of the materials predominant In pressing installations, temperatures existing are relatively constant, so you can't influence the fluidity of the resin by varying the temperature, not naturally wishing to vary the times of default pressing. Since the heat flow in all Compression mattresses have different speeds, being not However, regular, positive influence cannot be achieved in the viscosity of the resin or the fluidity of the resin by this parameter.

objective

The objective of the present invention is to propose a compression padding with the help of which a better diffusion of vapor bubbles getting, so Both a transparent and closed melamine resin surface, in particular, the liquid phase of the resin must be prolonged. Another object of the present invention is a process for pressing a product to be pressed with the one that can achieve the objectives indicated above.

Solution

The goal is achieved because the threads elastomers in the warp or weft of the compensation fabric of pressure and the metallic threads in the weft and in the warp of the compression padding of pressure compensation fabric are angled, the elastomeric threads having a diameter greater than the metallic threads and presenting the metallic threads also in the crests of its waves a distance from a plane formed by the wave crests of elastomeric threads, so that the thickness in the uncompressed state of the compression padding is determined by elastomeric threads.

In compression padding according to invention, a controlled heat flux is advantageous by way of heat flow as a function of pressure.

The parts of the pressing installation in hot coming into contact with the product to be pressed, in particular the pressure plates, caused by the temperature existing at the beginning of the pressing process a fusion of the melamine resin, which means at the same time a reduction of the viscosity of the resin. The heat flow is done during this time substantially only through the elastomeric threads, since the metal wires do not yet come into contact with the hot plate and pressure plate. Since the viscosity or the degree of crosslinking of the resin depends on the temperature, the Liquid phase of the resin is prolonged until the metallic threads of the compression padding come into contact with the hot plate heat conveyor and pressure plate due to increased The pressing force. Precisely at the moment when all acts The pressure of the hot pressing installation is when generates a greater heat flow (it is now when the metallic threads they come into contact with both the hot plate and the plate pressure, so the thermal conductivity of the padded). Therefore, there is an increase in viscosity of the resin or the degree of crosslinking of the resin. In consecuense, a transparent and closed surface is formed, unlike the known compression mattresses. Even in case of structures deep stamping and relatively total pressing times short, thanks to the optimal pressure distribution form impeccable surfaces. The compression padding according to the invention thus allows a delayed increase in time of the existing temperature on the surface of the padding of compression to provide more time for resin fluidity thanks to an extension of the "temperature phase low".

The compression padding according to the invention It presents some metallic threads both in the form of warp threads as in the form of weft threads, so the padding of Compression has great shape stability.

According to the invention, elastomeric threads high temperature resistant are arranged in the form of threads of warp or weft threads alternating with metallic threads. In this sense, they may be willing to alternate respectively an elastomeric thread and a metallic thread or respectively an elastomeric thread and two or three metallic threads or vice versa, the invention should not be limited to the variants previously indicated.

It is advantageous if the diameter of the threads elastomers is at least twice, preferably three times, larger than the diameter of the metallic wires. As increases the ratio of the diameters of the elastomeric threads to the of the metallic threads increases the duration of the liquid phase of the resin and, therefore, the period of time in which the vapors can be spread on the paper band during the process of pressing. However, excessive wire diameters elastomers go against the need to get times of short pressing.

Due to the high temperatures that act on a compression padding it is advantageous to make the threads elastomers of high temperature resistant elastomers such as, for example, silicone rubber, fluorinated silicone rubber, rubber fluorinated or a copolymer of the rubber types above mentioned.

The stabilizing core threads may be made from individual filaments, being in turn advantageous for high-resistant soul threads temperatures such as, for example, polyaramides, such as filaments Kevlar or Normex.

In addition, for reasons of stability, it is especially favorable that the elastomeric threads are provided with metallic core threads of individual threads or threads braided metal such as, for example, braided wires of copper, brass braided wires, steel braided wires (fine), etc.

To further improve the properties of thermal conductivity of compression mattresses, threads elastomers may contain in the elastomeric coating thermoconductive materials, such as metal powders.

According to DIN 7724, elastomers are materials polymers that in the temperature range of use they have an elastic entropy (elasticity like rubber). The elastomers, which in German are also called rubber (with the exception of hard rubber) or vulcanized materials, are formed by a wide mesh crosslinking according to the main valences of rubbers or by crosslinking copolymerization of products of low molecular weight heading. Elastomers cannot substantially deform neither by heat action nor by moderate pressure Its residual tensile strain is lower at 2%.

As for the procedure, the objective mentioned at the beginning is done by a procedure for the pressing a product to be pressed in an installation Hydraulic hot pressing with a hot plate, a sheet pressure and a pressure compensation fabric arranged between these, in particular, one of the compression mattresses previously described, in which, in a first stage, set a moderate pressure, so that the contact points of compression padding with hot plate and sheet metal pressure are formed by elastomeric threads of the fabric of pressure compensation being carried out in a second stage an increase of the pressure to a total pressing force, compressing the elastomeric wires such that other contact points are formed by the metallic threads of the pressure compensation fabric.

Example of embodiment

Next, the invention will be explained more in detail from an exemplary embodiment of a compression padding that is represented in the drawings, in the that:

Figure 1 shows a twisted wire of threads brass,

Figure 2 shows an elastomeric thread with thread soul,

Figure 3 shows a quilting fabric of compression according to the invention in a top plan view, and

Figure 4 shows a section through the compression padding fabric according to figure 3.

Figure 1 shows a metallic braided thread of braided individual brass 2 strands, using this metallic thread 1 both in the form of warp thread and in the form of weft thread of a pressure compensation fabric 6.

In figure 2 a thread is represented elastomer 3, which is made from a core thread 4 and a elastomeric coating 5, for example of a silicone copolymer fluoridated / silicone rubber. The soul thread 4 is made to from braided copper wires. In the present example, the thread elastomer 3 is used in the form of weft yarn of the fabric of pressure compensation 6.

In the top floor view represented in Figure 3 of the pressure compensation fabric 6 according to the invention can be seen the elastomeric threads 3 bent upwards in the weft or the metallic threads 1 bent in the weft and in the Compression padding fabric warp. The threads elastomers 3 have a diameter clearly larger than the threads metallic 1, the diameter of the elastomeric threads 3 being in shape advantageous at least twice that of metal wires one.

Figure 4 shows a section through the compression padding according to the invention according to the figure 3, which is arranged in a pressing installation between a plate hot 7 and a pressure plate 8. Having established a moderate pressure, the contact points of the compression padding they are formed first only by elastomeric threads 3. All metallic threads 1 also present at their end points ("wave crests") a distance from the plane formed by the end points "wave crests") of the elastomeric threads 3, So the thermal conductivity is first lower. When subsequently the pressure is increased to the total force of Pressed, braided brass wires 2 form other points of contact 9, so that more heat flow is achieved Quick.

List of reference signs

one

Metallic thread

2

Brass thread

3

Elastomeric thread

4

Soul thread

5

Elastomer coating

6

Pressure compensation fabric

7

Hot plate

8

Pressure plate

9

Contact point

Claims (15)

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1. Pressure compensation fabric (6), in particular a compression padding, suitable for use in hydraulic hot pressing installations, comprising

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some metallic threads (1), both in the form of warp threads and in shape of compression padding weft threads, and

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some high temperature resistant elastomeric threads (3), preferably with core threads (4) stabilizers, which are arranged in the form of warp threads or in the form of threads of weft alternating with the metallic threads (1),

characterized in that the elastomeric threads (3) in the warp or in the weft of the pressure compensation fabric (6) and the metallic threads (1) in the weft and in the warp of the compression padding of the pressure compensation fabric (6 ) are layered, the elastomeric threads (3) having a diameter greater than the metallic threads (1) and also the metallic threads (1) presenting at their wave crests a distance of a plane formed by the crest of the wave of the threads elastomers (3), such that the thickness in the uncompressed state of the compression padding is determined by the elastomeric threads (3). 2. Pressure compensation fabric (6) according to claim 1, characterized in that the diameter of the elastomeric threads (3) is at least twice the diameter of the metallic threads (1). 3. Pressure compensation fabric (6) according to claim 1 or 2, characterized in that the diameter of the elastomeric threads (3) is at least three times larger than the diameter of the metallic threads (1). 4. Pressure compensation fabric (6) according to one of the preceding claims, characterized in that the elastomeric threads (3) are made from silicone rubber. 5. Pressure compensation fabric (6) according to one of the preceding claims, characterized in that the elastomeric threads (3) are made from a fluorinated silicone rubber. 6. Pressure compensation fabric (6) according to one of the preceding claims, characterized in that the elastomeric threads (3) are made from a fluorinated rubber. 7. Pressure compensation fabric (6) according to one of the preceding claims, characterized in that the elastomeric threads (3) are made from a copolymer formed by a part of fluorinated silicone rubber and silicone rubber. 8. Pressure compensation fabric (6) according to one of the preceding claims, characterized in that the core threads (4) are made from individual filaments. 9. Pressure compensation fabric (6) according to one of the preceding claims, characterized in that the core threads (4) are resistant to high temperatures. 10. Pressure compensation fabric (6) according to one of the preceding claims, characterized in that the core threads (4) are made from metallic threads. 11. Pressure compensation fabric (6) according to one of the preceding claims, characterized in that the metallic threads are braided. 12. Pressure compensation fabric (6) according to one of claims 1 to 10, characterized in that the metallic threads (1) consist of individual threads. 13. Pressure compensation fabric (6) according to one of the preceding claims, characterized in that the elastomeric threads (3) contain thermoconductive materials in the elastomeric coating. 14. Pressure compensation fabric (6) according to one of the preceding claims, characterized in that a non-metallic, high temperature resistant yarn material has been mixed with the warp or weft metallic threads to control heat. 15. Procedure for pressing a product to be pressed in a hot-press hydraulic installation with a hot plate (7), a pressure plate (8) and a pressure compensation fabric (6) disposed between them , in particular, a compression pad, according to one of claims 1 to 14, characterized in that, at a first stage, a moderate pressure is established, such that the contact points of the compression pad with the hot plate (7 ) and the pressure plate (8) are formed by elastomeric threads (3) of the pressure compression fabric (6), a pressure increase to a total pressing force being carried out in a second stage, the elastomeric threads being compressed ( 3) in such a way that other contact points (9) are formed by the metallic wires (1) of the pressure compensation fabric (6).