DE2455818A1 - PROCESS FOR MANUFACTURING FIBER BOARDS BY THE WET PROCESS IN A HOT PRESS - Google Patents

Description

Dr.-lng, WALTER STARK

PATENT ADVERTISER / 455818

D-4150 Krefeld 1 Moerser Straße 140 Telephone (02151) 28222 and 20469.

Date November 25, 1974

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_M en sign 2 TDO 74 275

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Becker & van Hüllen Niederrheinische Maschinenfabrik :, 415 Krefeld., Untergath 100

Process for the production of Paser plates in the wet process in a hot press

The invention relates to a method of manufacturing of fiberboard "in the wet process in a hot press.

In the wet process, the partially already dewatered but still wet fiber fleece lying on a sieve is first mechanically dewatered by closing the hot press under increasing pressure. The temperature of the hot press is around 180 to 225 ° C. . The pressure is then released to approximately 5 to 10 kp / cm ² within 5 to 10 seconds. During a period of about 3 minutes, the

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Moisture remaining in the pressed material up to a value of · u = 5 to 8 percent evaporated. The moisture content u be is correct according to the following equation:

u = ^m u " ^m o

In this equation mean

u Moisture content of the Paser plate

m ₀ mass of the Paser plate in absolutely dry

State
m _u Mass of the fibreboard when wet.

After the aforementioned evaporation phase, there is another one

Pressure build-up to about the maximum pressure of 50 to 60 kp / cm, which is held for about 30 seconds to 2 minutes. In this so-called post-curing stage also takes place further attenuation the residual moisture in the pressed material takes place, up to values around or below 1 percent.

! Those pressed into shape in this way. Fiberboard .. will. Then

after opening the press taken out of this.

Following this known pressing process, it is necessary to air-condition the fiberboard; ¹ because after leaving the press, the fibreboards take moisture out of the hygroscopic equilibrium according to the principles of the establishment of the hygroscopic equilibrium. surrounding air until a value of u = 6 to 8 percent is reached. However, this process must be controlled in such a way that no deterioration in the quality of the

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Paser plates occurs. One therefore leads a controlled one Air conditioning in here for specially designed air conditioning ducts by. No further explanation is required that such a Air conditioning is quite expensive.

The invention is therefore essentially to the task reasons, a process for the production of Paser plates in Develop a wet process that does not compromise quality Paser plates with a residual moisture content between about 6 to 8 percent can be finished pressed, so that air conditioning can be omitted. Furthermore, the pressing time should be shortened as a whole, if possible.

To solve this problem, the invention is based on the known Pressing process, in which the still wet nonwoven is mechanically placed in the press under increasing pressure drained and after reaching the maximum pressure to the next Compression held briefly at maximum pressure and then further moisture is evaporated while relieving the pressure. However this evaporation phase takes place according to the invention not with strong pressure relief but only with lowering of the pressure to about 50 percent of the maximum pressure. This phase is carried out until there is residual moisture of u = approximately 8 to 10 percent is reached. Then the , Print while maintaining the same density and thickness of the .gepreßten plate down to 0 with a residual moisture of 6 to Percent degraded relatively slowly.! When aem according to the invention

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In the process, the evaporation level is between 30 and 120 Seconds, while the metered pressure reduction down to 0 takes about 20 to 60 seconds.

If the production of the Paser plates in multi-daylight presses takes place, ^ what is common, must according to the invention with a precisely working simultaneous locking device worked ' will. Such presses with simultaneous closing devices are has long been known in the relevant technology.

The method according to the invention can also be further improved, especially with regard to the pressing time, if, according to a proposal according to patent application P 24 53 517.9, which is not yet part of the state of the art, the wet fiber fleece is dewatered with the addition of wetting agents. This enables significantly better moisture contents to be achieved when feeding the fiber fleece into the press. Without wetting agents, the feeding values are u = 200 percent, while when using wetting agents, values of u = 90 percent are achieved.

In the drawing, the pressing process is explained in more detail using various diagrams. Each figure points from below Above the print program, the course of the fiber fleece mat or board ceiling as well as the humidity, expressed in percent absolutely dry (atro) fiber. In detail represent '.., ..'

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"Pig."! 1 the normal pressing method;

Pig. Figure 2 shows the pressing method according to the invention;

Fig. 3 like Pig. 2 but using wetting agents.

In all Piguren are those shown in the print program Letters'dar

A-B-C the drainage phase

D-E the evaporation or evaporation phase

It can be seen that in all three palls the drainage phase basically the same. At relatively fast

If the pressure rises up to 55 kp / cm, most of the water, which can still be removed mechanically, is squeezed out and, while maintaining the maximum pressure, the material to be pressed is up to the desired finished thickness of 3.2 mm _; i compacted to a bulk density of at least 1.0 g / cm.

In the subsequent evaporation phase, the previous Process the pressure is reduced very strongly to 8 kp / cm and further water evaporates from the pressed material over a relatively long period of time. From the humidity diagram at the end of this phase can be a rate of u = 5 percent remove. In contrast, in the inventive

Process the pressure only reduced to 26 kp / cm and over a shorter period of time up to a residual moisture content of 10 percent evaporates ". '

According to Pig. 1 the further pressing process takes place, the so-called post-curing stage F-G-H »in the previous process with another pressure increase up to 55 kp / cm and with further evaporation of residual moisture. The finished Plates leave the press with a residual moisture of about 1 percent. The pressure reduction G-H until the Press then takes place very quickly.

In contrast, in the method according to the invention after the end of the evaporation phase, the pressure is metered and, above all, very slowly at the end, as can be seen from the curve E-P. The residual moisture at removal from the press is 6 percent.

The diagrams according to Pig. 3 differ from those according to Pig. 2 essentially in that the fiber fleece is fed into the press with a much lower moisture content of around 95 percent, which naturally in the evaporation phase D-E results in a shorter time and thus an overall shorter pressing time. the Feed moisture in the press programs according to Pig. 1 and are at u = 200 percent.

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Claims (3)

Expectations 1.! Process for the production of fibreboard using the Hass process in a hot press, in which the still wet fiber fleece is initially under increasing pressure in the press mechanically drained and after reaching the maximum pressure for further compression is briefly held at maximum pressure, then under pressure relief further moisture is evaporated, characterized in that that for evaporation the pressure is reduced to about 50 percent of the maximum pressure and at this pressure down to one Residual moisture of u «8 to .10 percent is evaporated, then the pressure while maintaining the same density and thickness of the pressed plate up to 0 with residual moisture from u ss 6 to 8 percent is degraded relatively slowly. 2. The method for the production of Paser plates according to claim 1, characterized by the use of a multi-daylight press -with simultaneous locking device. 3. A method for the production of Paser plates according to claim 1 and / or 2, characterized by the use of wetting agents for better drainage of the fiber fleece. 609823/0066 Le e rs ei \ e