WO2002094522A1

WO2002094522A1 - Method for the continuous production of fiber plates

Info

Publication number: WO2002094522A1
Application number: PCT/EP2002/005220
Authority: WO
Inventors: Peter Beck
Original assignee: Metso Paper, Inc.
Priority date: 2001-05-21
Filing date: 2002-05-13
Publication date: 2002-11-28
Also published as: DE10124929B4; DE10124929A1

Abstract

The invention relates to a method for the continuos production of fiber plates consisting of plate materials comprising fibers stuck together by a binding agent and hardened under pressure and heat in a double-band press (100), wherein the fibers provided with the binding agent are dispersed in an inlet (60) of the double-band press on a horizontal trunk of a conveyor belt to form a bulk material (4') and are hardened under pressure and heat in a pressing path (3) located between the upper trunk (2') and the lower trunk (1') synchronously running in the same direction of advancement (16) of the double-band press (100) so as to form a web (4) from the plate material. Method parameters such as fiber mat humidity, fiber mat temperature, type of adhesive used and/or gluing factors are set, controlled or regulated in the inlet (60) depending on the method parameters of the pressing process such as press speed, heating temperature, cooling temperature, etc. with the purpose of achieving a target production speed and residual humidity in the plate material after it has left the pressing path (3).

Description

Process for the continuous production of fiberboard

The invention relates to a method according to the preamble of claim 1.

Such a method is known for example from DE 198 10 304 C1.

In the production of fiberboard materials, which are known depending on their density under the abbreviations HDF (high density fiberboard), MDF (medium density fiberboard), LDF (light fiberboard) and SLDF (super light fiberboard), there must be a significant increase in the first zone of the press section. before heat is introduced into the material of the bed in order to carry out the hardening reaction of the binder. The moisture contained in the bed serves to transport the heat into the bed and plasticize the bed. In a rear, i.e. Subsequent, towards the end of the pressing section, the heat supply no longer has to be as great, but it is mainly about maintaining the pressure, so that initiated bonds within the smooth material are not torn open by premature relief from complete hardening and so on destroy the board materials.

In the method known from DE 198 10 304 C1 or in the known double belt press, a recooling zone is therefore provided in a rear section of the press section, within which heat is removed from the web being formed, but the pressure is at least essentially maintained. In order to increase the production speed, as far as possible cooling in the rear section of the pressing section is desirable, since this means that cooling devices downstream of the pressing section can be dispensed with and fluctuations in the bed (e.g. moisture, temperature) influence the product quality far less.

The invention is therefore based on the object of developing a generic method in such a way that the production rate of fiberboard which can be achieved with the double belt press is increased while at the same time maintaining the desired panel properties.

This object is achieved in a first aspect by the method set out in claim 1 and in a second aspect by the method set out in claim 2.

Surprisingly, it has been found that the production rate can be achieved while maintaining or improving the sheet properties if the bed of the material to be pressed is preheated before the inlet. Heat is particularly preferred, which heats the bed (or also fiber mat) up to a maximum of 100 ° C. The heating can be carried out in any way, for example by water or steam spraying or also by microwave heating.

The problem on which the invention is based is also solved according to the invention if one or more of the process parameters which can be varied at the press inlet - such as fiber mat moisture, fiber mat temperature,

Amount of water spraying on both sides of the fiber mat, choice of glue type, gluing factors - as well as the process parameters in the press section - such as heating temperature, cooling temperature, press speed, specific press pressures, press factors (ie press time / plate thickness) - depending on the desired press plate properties when exiting the press section - such as Bulk density and residual moisture of the press plate - adjusted, controlled or regulated. It also falls within the scope of the invention to combine the methods according to claims 1 and 2 with one another. The preferred ranges of variation of the parameters to be changed are specified in the subclaims.

The drawing shows an embodiment of a double belt press suitable for carrying out the method according to the invention in longitudinal section.

The double belt press, designated as a whole by 100, is used to produce fiberboard, which consist of fibers bound by means of a binder which cures under pressure and heat. It comprises an upper forming belt 1 made of sheet steel of approximately 2 to 3 mm in thickness and an equally lower forming belt 2. Between the forming belts 1, 2, a web 4 is compressed in the pressing section 3 from a bed which is fed to the pressing section at the inlet 60 , which consists of the fiber material provided with the binder, which after pressing results in one of the aforementioned materials.

The upper forming belt 1 runs around rollers or drums 5,6 arranged transversely to the web and can be hydraulically tensioned between these drums 5,6. Correspondingly, the forming belt 2 runs over drums 11, 12 arranged transversely to the web 4, which also achieve hydraulic tensioning of the forming belt 2. The shaping belts 1, 2 are driven via the drums.

The forming strips 1, 2 run through the device in the sense indicated by the arrows 16. In the pressing section 3, the lower run 1 'of the upper forming belt 1 and the upper run 2' of the lower forming belt 2 move closely one above the other. The bed 4 'applied to a conveyor belt (not shown) on the left in the drawing is drawn into the pressing section 3 and compressed between the runs 1', 2 '. The bed 4 'passes from the conveyor belt to a rolling tray 7 which places the bed onto the lower forming belt 2 shortly before the upper one Top of the drum 11 passes. The outgoing, finished pressed and hardened web 4 of the plate material is divided on the right side according to the drawing by suitable devices, not shown, and conveyed away.

In the pressing section 3, an upper support structure 17 is provided in the inner region of the forming belt 1 above its lower run 1 ', which cooperates with a lower support structure 18 provided in the inner region of the lower forming belt 2 below its upper run 2'. The support structures 17, 18 support the areas of the shaping tapes 1, 2 facing the web 4 against the web 4 and press them against one another with great force.

The support structures 17, 18 each consist of individual supports 19, 20, which are arranged in pairs one above the other above and below the forming strips 1, 2 and the web 4. Each pair of supports 19, 20 is clamped together by strong spindles, not shown, located laterally outside the press section 3, so that individual pressure members are formed which are self-contained in terms of force.

There are strong ones between the carriers 19, 20 and the fornibands 1, 2

Support plates 26, 27, which transmit the force exerted by the individual supports 19, 20 evenly to the forming belts 1, 2 and thus to the web 4. The support plates 26, 27 have channels which run transversely to the web 4 and run through their width and through which a heat transfer medium can be passed. The channels follow each other closely in the direction of travel 16 and are connected to one another at the ends by pipe bends, so that groups of channels are flowed through in a meandering manner by a common heat transfer medium.

Between the mutually facing sides of the support plates 26, 27 and

Form bands 1, 2 are arranged roller chains 30, on which form bands 1, 2 roll on support plates 26, 27 and which circulate endlessly in a vertical longitudinal plane around support plates 26, 27 within form bands 1, 2. fen. The rollers of the roller chains 30 transmit both the pressure and the heat of the support plates 26, 27 to the forming belts 1, 2 and thus the web 4 that is being formed. The forming belts 1, 2 are thus subjected to a purely rolling support in the pressing section 3.

The press section 3 is divided into two sections 3 'and 3 "which follow one another in the running direction 16 of the web 4. In the first section 3', the heat is supplied by the heating of the heat transfer medium, which causes a certain formation of steam in the compressed bed 4 'and the hardening of the binder contained therein. The heat transfer medium, for example a

Thermal oil is heated and circulated in a heat exchanger 40, so that the heat medium which has just been heated is fed in the direction of arrow 41 at the beginning of the first section 3 ′ and in the direction of arrow 42 at the end of the first section again from the channels of the support plates 26, 27 removed and returned to the heat exchanger 40 in a closed circuit. As shown, the heat exchanger can in turn be acted upon by a further heat transfer medium heated in a heating unit 43 with heating registers 44, or it can itself contain the heating.

In the rear, i.e. in the running direction 16 of the web 4, section 3 "of the pressing section 3, the pressure must be maintained until the binder has hardened and the vapor pressure has been reduced sufficiently, otherwise the bond just formed in the binder will tear again. Through the support plates 26", 27 " this section, a heat transfer medium is also circulated such that it is supplied at the beginning of section 3 "in the direction of arrow 51 and is removed again at the end of section 3" in the direction of arrow 52.

Here, too, the heat transfer medium flows through a heat exchanger 50, in which, however, no heat is supplied to it, but on the contrary, part of the heat supplied in the first section 3 ′, which is caused by the movement of the

Form tapes 1, 2, the roller chains 30 and the web 4 in the rear section 3 "has been reached, is withdrawn again. The extracted heat relaxes the steam and thus reduces the steam pressure.

The heat extracted in the heat exchanger 50 is used in an aggregate 53, which is only symbolically indicated in the drawing, be it for heating purposes or be it at a point upstream of the process sequence for heating the particles on the left side of the drawing Drying the particles to be used for heating water and / or thermal oil or for similar purposes. In this way, the heat balance of the overall system is improved and also a contribution to environmental protection is made, insofar as the leakage of substances such as formaldehyde and the like is reduced.

The channels formed transversely to the track 4 in the support plates can be connected differently to groups in succession in the running direction 16. The passage of a further heat transfer medium, which is not heated, through the second section 3 ″ can also take place if the support plates 26, 27 and the roller chains 30 are designed to be continuous over the entire length of the pressing section 3.

In the exemplary embodiment shown, however, the sections 3 ', 3 "are separated not only from one another with regard to their loading with heat transfer medium, but also mechanically. In the first section 3', separate support plates 26 ', 27' are located opposite one another above and below the web 4 which extend from the inlet to a point 28 at the end of the first section 3 'and are encircled by associated endless roller chains 30'. At point 28 separate support plates 26 ", 27" begin therefrom which extend to the end of the pressing section 3 or of the rear section 3 "and are encircled by separate roller chains 30". The separating point 28, at which the shaping tapes 1, 2 pass from the first section 3 'into the rear section 3 ", is made as short as is structurally possible is. Because of the required deflection of the roller chains 30 ', 30 "over a radius, the supported tongue-free section at point 28 about 150 mm, which is irrelevant for the failure of the plate material.

Due to the subdivision at point 28, the front roller chains 30 'remain completely in the first section 3' and cannot heat in the rear

Section 3 "transferred.

The heat that nevertheless arrives in the rear section due to the shaping belts 1, 2 and the web 4 is withdrawn in part in the heat exchanger 50 from the heat transfer medium flowing through the support plates 26 ″, 27 ″ and used.

When carrying out the method according to the invention - as described at the beginning - the variable process parameters of both the material to be pressed at the inlet 60 and the process parameters in the press section are set, controlled or controlled with regard to the production speeds and properties of the plate material to be achieved after leaving the press section regulated, in the last two cases the double belt press is still equipped with devices (not shown in the drawing) for detecting and influencing the process parameters to be varied.

Claims

PATENT CLAIMS

1. A process for the continuous production of fiberboard from a material held together by a fiber that is cured under pressure and heat, in a double belt press (100), in which the fibers provided with the binder at an inlet (60) of the double belt press (100) onto a horizontal The strand of a conveyor belt is sprinkled into a bed (4 ') and in a pressing section (3) between the upper strand (2') of a metal endlessly rotating lower forming belt (2) and the lower strand running in the forward direction (16) of the double belt press (100) (1 ') of a metallic upper shaping belt (1) under pressure and heat to form a sheet which results in the plate material

(4) are cured, the working pressure and the heat necessary to bring about the binding in the press section (3) being transferred from the support structure (26, 27) to the shaping belts (1, 2) and by these into the bed (4 ') are, wherein in a rear section (3 ") of the press section (3) of the web (100) heat is withdrawn, characterized in that the bed (4 ') is preheated so that the fiber mat temperature at the inlet (60) increases is.

2. A process for the continuous production of fiberboard from a material held together by a fiber held together under pressure and heat in a binder, in a double belt press (100), in which the fibers provided with the binder at an inlet (60) of the double belt press (100) onto a horizontal Run of a conveyor belt sprinkled into a bed (4 ') and in a pressing section (3) between the upper run (2') of a metal endlessly rotating lower forming belt (2) and the lower run running in the forward direction (16) of the double belt press (100) (1 ') of a metallic upper shaping belt (1) under pressure and heat to form a sheet which results in the plate material (4) are cured, the working pressure and the heat necessary to bring about the binding in the press section (3) being transferred from the support structure (26, 27) to the shaping belts (1, 2) and by these into the bed (4 ') are removed, in a rear section (3 ") of the press section (3) of the web (100), characterized in that the process parameters fiber mat moisture and / or fiber mat temperature and / or types of glue and / or gluing factors at the inlet (60 ) depending on the process parameters heating temperature and / or cooling temperature and / or press speed and / or specific press pressures and / or press factors with regard to a production speed and residual moisture to be achieved in the plate material after leaving the press section (3) can be set, controlled or regulated.

3. The method according to claim 1 or 2, characterized in that the fiber mat moisture at the inlet (60) is 6 to 18%.

4. The method according to claim 1 or 3, characterized in that the fiber mat temperature at the inlet (60) is 15 to 45 ° C.

5. The method according to any one of claims 1 to 4, characterized in that the fiber mat temperature at the inlet (60) is a maximum of 100 ° C.

6. The method according to any one of the preceding claims, characterized in that at the inlet (60) there is preferably water spraying of the fiber mat on both sides and / or steam spraying with separating agents of 5 to 50 g / m ² per fiber mat width.

7. The method according to any one of the preceding claims, characterized in that urea formaldehyde and / or melamine as glue types

Urea-formaldehyde and / or isocyanate and / or phenol can be used.

8. The method according to any one of the preceding claims, characterized in that the gluing factor is 6 to 28 kg of glue / 100 kg of fibers.

9. The method according to any one of the preceding claims, characterized in that the temperature in the first region of the pressing section is 100 to 280 ° C.

10. The method according to any one of the preceding claims, characterized in that the temperature in the rear section (3 ") of the pressing section

150 to 20 ° C.

11. The method according to any one of the preceding claims, characterized in that the forward speed of the web (4) in the press section 0, 3 to 120 m / min. is.

12. The method according to any one of the preceding claims, characterized in that the specific pressure is 1 to 7N / mm ² .

13. The method according to any one of the preceding claims, characterized in that the pressing factor is 3 to 18 sec / mm plate thickness.

14. The method according to any one of the preceding claims, characterized in that the residual moisture of the press plate behind the press section is 3 to 15%.