DE1295181B - Process for the production of hardboard with curvatures - Google Patents

Description

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Has the known method for the production of mungen. This will make the application hardboard have the disadvantage that they are only available for products made from fiber mats Deliver flat or slightly curved panels. significantly enlarged, so can z. B. Kraftfahr-Es There are different methods, in three prostitutes door panels, packaging trays, air sions produce irregularly shaped hardboard panels, door panels, chair backs and other furniture, but none of these methods appear to be split, game table tops, trays and the like made to prove completely. In the usual wet process.

it is possible to give the hardboard a slight cure- The squeezing process can be carried out

venform or slight bends when using the whole mat or part of the panels suitably shaped in the hot press at the same time as the mat to be made pliable. If one wants to compress the flat fiber cakes into bodies, for example pressing them in a press with stronger curvatures or by tamping the mat,
If the fiber cake tears through the necessary pressure, the mat is preferably pressed

significant deformation. squeezed, which extends in one direction

There is therefore a method for producing angular, successive surface areas of the mat formers Developed hardboard, which is affected by the ten surface, with the help of whale fiber mat is preformed. After a warping, because this process causes the mat to bend wet pulp becomes more soft and elastic on a mold than it is deposited together, which is roughly the final shape of hard pressing the entire mat at once. When rolling fiber board, and dried on this form. To be used or the like, it is best to use the mat This method has the disadvantage that it practically first run through the rollers in one direction it is impossible to leave the preformed mat ready for processing and then in a direction that is perpendicular to transport workers. Since the mat is in particular to the first direction, a mat with Way must be preformed to achieve the desired uniform extensibility in both directions This process is costly to obtain the end product.

playful and with regard to the handling of the previous Further improved results are obtained when

formed panels problematic. According to another method of both squeezing the dry mat and method, shapes are bent by centrifugal molding so that not only the fiber bond is aimed at, according to which a pulp is partially broken by the mat, but also nip centrifugal force against one Sieve of the desired planes are created, which is mainly forced parallel to the shape, whereupon heat and pressure run on the surface of the mat. As a result, conditions are used which create a layer that is practically parallel to the white hardening process. However, this is not enough to extend the surface of the mat and to reach the gap in order to level the strength of conventional hardboard panels only so loosely that they adhere to one another. The latter process is costly, a relative sliding movement between the layers, and the product is only possible for a certain few.
Purposes. The crushing and bending treatments can

Attempts have also already been made to be carried out simultaneously by air-fil- ing, or the bending as well as a semi-dry Fourdrinier form- can follow the squeezing,
move a mat with greater elongation or displacement. However, we have not succeeded in producing a form of a good, unidirectional, flat mat that is easy to handle, but achieves the best results and, at the same time, a satisfactory stretch and the most supple mat if you can first get it shows when it is pressed in molding dies 45 in one direction and then in a transverse direction. the first direction bends. The bending should be like this

The invention has set itself the task of being carried out in such a way that the desired splitting processes of the type mentioned at the outset are created without the occurrence of cracks running in a simple and cost-saving bending direction in the mat at right angles to the fen.
Way flat mats with great extensibility and 50 If rollers or the like are used to produce the flexibility that can be squeezed in two directions in a mat or conveniently transported and bent to a flat state, the sequence of operations can result be:
send and squeeze the easily deformable in one direction, subsequently or in matrices

are. at the same time bending in that direction and then

The invention solves the problem in that a 55 squeezing in a direction transverse to the first dry mat of tied wood direction and then or at the same time bending fibers by squeezing them into a mat with increased in this transverse direction. Instead, you can Flexibility and extensibility is transferred, where- work in the following order: squeeze first with the bond between the individual fibers partly in one direction and then across it, then is wisely broken, and that this mat will then bend in one of these directions and bite on it in the usual way in one die to the opposite in the other direction. Another old wish Shape shaped and there under heat native sequence is: squeezing in one direction, effect is compressed. then bending in both directions and then

By the method of the invention, the mat is squeezed in a direction transverse to the first so pliable and elastic that it can also move in the 65 direction.

Shape of a curved die is much better The mat that can be made flexible can be made of

adapts and without the formation of cracks to a grain of a wet fibrous web be made, which through can be deformed and pressed by, the crumbling, opening up and refining of pieces of wood and

3 4

subsequent shaping and dewatering on a th partial break of the fiber bond and the formation of

Forming machine, for example a Fourdrinier cleavage plane, would prevent

machine, by conventional hardboard-making The dried mat is then a squeeze

position procedure was generated. However, it is subject to a wün process, preferably also one

worth seeing, one evenly over the entire 5 bending process.

Use fiber mass distributed binder. The drawing shows an example of a device

The amount and type of binder depends on the intention with which the process according to the invention is carried out.

formed from. Can be used as a binder, for example.

the following materials alone or in combination Fi g. 1 shows schematically in elevation a plant,

suitable: thermosetting resins, e.g. B. Phenolform- io for squeezing the mat in the invention

aldehyde and melamine formaldehyde, thermoplastic processes according to the invention is suitable, with the

Resins e.g. B. Asphalt, »Vinsol« (a thermoplastic lines of force and the resulting cleavage planes

Resin obtained from pine wood; it contains hints are;

Phenol, aldehyde and ether groups) and wood resins, Fig. 2 is an elevation similar to Fig. 1 but shows

Petroleum hydrocarbons, drying oils 15 the squeezing and bending process;

of vegetable, animal or mineral origin, F i g. 3 is a perspective view of a

z. B. linseed oil and rubber milk, e.g. B. styrene-buta hardboard that was shaped in a die

diene, as well as polyvinyl acetate. It is best to be one that is;

Use combination of ties to get good fi g. Fig. 4 is a cross section along the line IX-IX

Forming behavior and also good physical ao from FIG. 3.

To achieve properties in the finished panel. F i g. Figure 1 illustrates an apparatus for thermoplastic resins to exhibit good plasticizing performance of crimping. F i g. FIG. 1 also shows the hot molding press and enables strong pulling without tearing the mat as the main forces in the process explained. Drying is understood. The forces and bean oils that occur, thermosetting resins and most chewing stresses are, however, of a complex nature. The pre-cooked milk types generally give the best conditions in terms of strength and water resistance. The amount of driving according to the invention will vary. It should therefore be added to the binder, depending on the type of binder and expressly noted that the invention should not be ^{restricted by the intended deformation normally between 1 and 25 0} Jo, based on the weight of the 30, based on the weight of the 30.

dry mat, and preferably between 4 and In F i g. 1 guide the guide rollers 10 and 11 the

10% lie. dry mat 12 by nip rollers 13 and 14.

Outer layers of paper, fabric, plastic or the like. Guide rollers 15 and 26 carry the squeezed can be used provided this mat. Due to the pressure at the gap between the rollers Cover layers are stretchable enough to occur in the 35 13 and 14 is created in the vicinity of the mat die not to tear. Even if it is for the surface, as indicated by arrows 17, a train most Applications is preferred to have a force that is greater than in the middle of the mat, such as To use evenly distributed binder, it can be indicated by arrows 18, so that squeezed in the suffice, the binder occurs locally on the th mat 20 shear forces. These shear forces Spray on areas of the mat where a larger 40 break the natural fiber bond in the mat, Greater strength is required. The binder can be shown in FIG. 2 is on the exit side of the gap a bending roller 19 is also arranged with a brush or on other suitable rollers 13 and 14. Way to be applied. The application can This bending roller and the guide rollers 15 σ on the wet fibrous web, the dried mat and 16 a are arranged lower than the squeegee roller or the squeezed mat before hot pressing 45 13 or the guide rollers 10 and 11, so that the take place. The mat is bent and split planes

The mat to be made flexible should stand that long. The tensile force which is dried on the roller 13 until it becomes relatively rigid, so that mat occurs (cf. arrow 17a in FIG. 2), will be higher due to the squeezing and bending of the bond than in the case of the device Fig. 1. See direct the individual fibers is partly broken, 50 is the time to be smaller on the lower side of the mat by the preferably with the simultaneous formation of fission arrow b indicated motor 17 as in Fig. 1. planar. The mat should have a density of 0.19 to 0.64 g / cm ³ , preferably 0.32 g / cm ³ , due to the action of the bending roller 19. The and the guide rollers 15 c and 16 a is bent, moisture will be below 10% and a tensile force will be preferred, as indicated by the arrow 21 make up 0.1 to 2%. If one is after 55 points, on the underside of the mat near the wet process generated mat does not occur so far ge guide roller 15 a, accompanied by a has been dried that the fibers with each other compressive force on the bending roller 19, as it is through To connect the individual fibers will tend, arrow 22 is indicated. The bending of the mat is adapted to the squeezing and bending without thus creating further shear forces within the mat that are necessary for the formation of cleavage planes. The splitting effect of breaking the fiber bond takes place in the squeezed mat 20a in FIG. Furthermore, the mats tend to be marked in the press with 23 α. The nip rollers 13 and steam bubbles form when the moisture 14 can be in the in Fig. 1 g. 1 and 2 is more than 2%. If the binder has been evenly distributed in the whale pulp under a pressure of 0.7 to 1.0 kp / cm ² , 6g zenspalt should be used for a mat of preferably 0.32 g / cm ³ drying time and temperature for the damp Exercise matte density. The rollers 13, 14 and 19 can be matched to the binder used in such a way that, for example, a diameter of 150 mm does not bind too far, since otherwise it would be the desired when a dry mat of 12 mm thickness

is treated. The roller 19 is arranged so that the bending angle is sufficient to produce the nip planes to the desired extent, but without being so large that the dry mat is broken or torn in a direction perpendicular to its surface. The bending angle Θ in FIG. 2 is the angle formed by a line 24 drawn parallel to the surfaces of the dry mat and a line 25 passing midway between rollers 13 and 14 and rollers 19 and 15 respectively α ίο (the roller 15 a of the roller 19 is opposite) passes through, is included. The value of the bending angle Θ will vary, but is about 5 to 20 ° for a mat 12 mm thick. The distance between the rollers 13 and 14 should be large enough to prevent the mat from being destroyed by bending it too suddenly. If the rollers 13 and 19 are 150 mm in diameter, a suitable center distance will be about 46 cm.

Is the flexibility of the mat enough after the first Treatment in a device according to FIG. 2 not off, she can have a second treatment in one direction be subjected to the first treatment transversely to the direction. Preferably the first treatment in the longitudinal direction of the mat and the second treatment transversely to it, as in this order tearing is less likely than reversed, but either can Order can be used. Repeated rolling with increased nip pressure and enlarged Bending angles can be beneficial for some products.

In successive bending processes, the bending angle can be increased so that reinforced Cleavage planes are created without the mat tearing.

The mat is pliable in every direction after the second bending treatment and resembles a thick one Carpet. It can be stretched up to about 30 to 60% in a die press. The mat thickness is usually be about 6 to 25 mm.

The flexible, dry mat is placed in a die press and pressed, for example at temperatures of 150 to 260 ° C. and pressures of about 28 to 141 kgf / cm ² and cycle times of 15 seconds to 10 minutes. A typical press cycle for a mat containing 2% drying oil and 2% Vinsol is 232 ° C, 84.5 kgf / cm ² , 1 minute.

Another typical press cycle for a mat containing 2V2% phenolic resin and 2Va% petroleum resin is 205 ° C, 42 kgf / cm ² and 3 minutes.

At high temperatures, moisture can cause bubbles to form in the mat, and it It may be necessary to dry the mat to a lower moisture content or a flexible one Insert a sieve insert in the die so that moisture can escape from one side of the mat.

If desired, the properties of the plate can be improved in a known manner by it is post cured in a heating chamber or by hot layering.

Figures 3 and 4 illustrate molds which can be pressed according to the method of the invention, namely a hardboard 17 which is provided with an inflection 27 in a die press has been.

The method of the invention is carried out by the following Example further explained.

example

A dry mat with a density of 0.32 g / cm ³ , a thickness of 10 mm and a moisture content of about 5% is produced including 2 ^{% / o linseed oil and 2 1} % petroleum hydrocarbons. The mat is rolled in its longitudinal direction between nip rolls with a nip pressure of about 0.84 kgf / cm ² , the in FIG. 2 is used. The bending and squeezing rolls have a diameter of 150 mm, the bending angle is about 10%, and the bending roll is 46 cm away from the next squeezing rolls. The mat is then rolled across its length, avoiding the same system and with the same nip pressure. The mat is then dried under a moisture content of 1% and then at a temperature of 232 ° C and a pressure of 84.5 kp / cm ² with a pressing time of 45 seconds to form a door panel, e.g. B. a motor vehicle door panel, molded and pressed,

Claims (13)

Patent claims: 1. A method for the production of hardboard with curvatures, characterized in that that a dry mat of wood fibers bound together by being squeezed into a mat with increased flexibility and extensibility is transferred, whereby the bond between the individual fibers is partially broken is, and that this mat is then in the usual way in a die to the desired Form is formed and pressed there under the action of heat. 2. The method according to claim 1, characterized in that the mat by a pressure is squeezed on successive surface areas extending in one direction acts on the mat surface. 3. The method according to claim 1 and 2, characterized in that following the first Squeezing treatment a second squeezing treatment is carried out, during which the pressure is applied successive surface areas extending in a direction transverse to the first direction the mat surface is exercised. 4. The method according to any one of the preceding claims, characterized in that the The mat is squeezed over practically its entire surface. 5. The method according to any one of claims 1 to 3, characterized in that the mat after squeezing it is bent while avoiding cracks, being generally parallel Cleavage planes that run towards the mat surface are created. 6. The method according to claim 5, characterized in that successive parts of the The mat can be bent with these parts extending in one direction. 7. The method according to claim 6, characterized in that the mat first in a Direction and then bent across it. 8. The method according to claim 6 or 7, characterized characterized in that the mat is bent over practically its entire surface. 9. The method according to any one of the preceding claims, characterized in that a stiff mat is assumed, the density of which is between 0.19 and 0.64 g / cm ³ , preferably 0.32 g / cm ³ and which is in a known manner by forming, dewatering and drying a wet lignocellulosic fibrous sheet. 10. The method according to claim 1 to 9, characterized in that the moisture of the wood fiber mat is below 10% and preferably 0.1 to 2%. 11. The method according to any one of the preceding claims, characterized in that the Mat has a moisture content of 0.1 to 2% and one over the entire fiber mass distributed thermosetting binder in an amount of about 1 to 25%. 12. The method according to claim 11, characterized in that a combination of thermoplastic and thermosetting resins is used as a binder in a manner known per se. 13. The method according to claim 7, characterized in that the made pliable mat is about 6 to 51 mm thick. For this purpose, 1 sheet of drawings 909520 / 4Π