DE1653245A1 - Particle board and process for its manufacture - Google Patents

Description

P ΑΓ ENTANWALI

DR. QUARDER STUTTGART

Rfchard-Wograr-SfraB 16 Telephone 244446

. .- September 9 , 1966

company
KUNZ & CO.

7162 Gschwend

Patent and utility model applications; Germany

Password; "Chipboard"

A 10 488
Dr. Qu / Sk

Particle board and process for its manufacture

The following properties are expected from a newly developed three- or multi-layer chipboard:

1.) High strength values according to DIN regulations with low spec. Weight;

2.) Outer layers with a closed surface and a homogeneous one Swelling behavior;

3.). Uniform layer thickness of the outer layers.

In the previous multilayer panels of this type, in particular complained about the following defects:

The different swelling of the top layer chips under the influence of water and / or solvent causes a more or less uneven surface in previously known panels, 009812/110

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especially when gluing thin veneers, weak laminate panels, PVC foils and the like.

The restless, partially not closed top layer of the surface occurs - as has been shown - especially when the Wood particles used for the top layers are of different thicknesses and the average thickness exceeds 2/10 mm.

Because of this lack in particular, there has been no shortage of attempts Manufacture three-layer panels that have a flawless. Ensure application of film-shaped coatings.

So are z. B. wood-based panels, in particular chipboard made of wood particles and / or woody plant particles and binders with a single or multilayer core and a leveling layer applied to one or both sides of the same known, in which the initial top layer of glued chipboard sanding dust, ie with cured glue or synthetic resin contaminated wood sanding dust (cf. DBP 1 097 656) ^X ^.

However, these wood-based panels do not have the required quality achieved. The application of the cover layers in a uniform thickness is not possible and consequently the plate tends to warp. Due to the low stamina, the plates for processing z. B. unsuitable in the furniture industry.

Furthermore, in the. a chipboard with last years fine-structured surface and high inherent strength, patent pending. This chipboard has one or more layers of coarser wood chips and, if necessary, different degrees of fineness Similar comminution products of vegetable raw materials that are commonly used for chipboard production, one or both sides with a Cover layer are provided, which originate from a mixture of binder-containing chipboard panels that have already cured from grinding Sanding dust with wood fibers and binding agents obtained in the dry process

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- 3 x) omit in print

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funds (see DAS 1 183 240) **.

Finally, the inventor of the aforementioned patent has published a system for the production of wood-based panels, which in particular consist of wood chips or similar particles contaminated with binding agents and with a layer on one or both sides made of wood fibers containing binders or those made of material containing lignocellulose. This system has an in known way, continuously operating fiber fleece generator with air-permeable fleece carrier and downstream pre-compressor in a chip web production line of known type switched on, wherein behind the switch-on point for simultaneous pressing of the chip fleece and the fiber cover layer applied to at least one outer side

x) a common heating press device is arranged (cf. DAS 1 206 147) '.

The wood-based panels described in the two last-mentioned publications cause considerable production Trivities, so that so far they have not yet received any appreciable input have found in practice.

All attempts to use homogeneous top layers Binder-like grinding dust has failed so far because it was simply not possible to achieve exact layer thicknesses. This means that panels produced in this way show a different planking effect and therefore tend to warp and warp.

Another shortcoming of these previously known facing panels is the fact that the sanding dust is much too "short", the individual dust particles can only be glued together butt. The strength of using grinding dust The top layers produced is therefore so small that the relatively loosely bound particles can be separated from one another with little stress.

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x) weighed in the print

The attempt finally, by adding fibers to the

Sanding dust is to compensate for the disadvantages of the dust cover layer.

so far not got beyond laboratory tests. -.

The inventor of the present application has < Set the task of laminated particle board with closed, in appearance and in behavior to produce a homogeneous surface against moisture without the disadvantages of lower strength, increased risk of warping α and possibly having to accept increased binder consumption. ·

Up to now it has been customary to use “homogeneous top layers made of flax chips about 0.2 mm thick, about 10-22 mm long and about 1-5 mm wide. In the case of such a chip mixture, in particular the chip material deviating in thickness is undesirable, especially since thicker chips are only imperfectly separated by sieving and sifting processes can.

If these coarser chips get into the other chips, which fluctuate more or less strongly around the average chip thickness Cover layers, then they solve in the pressed board when moistened by glue or the like. A different local swelling and thus the surface looks uneven.

Due to his extensive experiments, the inventor has gained the knowledge that it is necessary to solve the problem at hand What matters is to find a substance that is as little as possible around a given one Thickness value fluctuates. It is therefore important to produce chips that are as slender as possible with a fiber-like structure, their Slenderness, i.e. the ratio of diameter to length, is on the order of 1 in 50 to 1 in 200. This means, /

that the chip diameter is less than 0.1 mm and its length in the Around 5 mm. This for the production of the top layers Material used according to the invention largely resembles a chip in terms of its length and in terms of its round-elongated shape Cross-section largely of a fiber.

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QfHGtNAL INSPECTED

After the good usability of such fiber chips for the top layers to be produced had been identified, it was important to use this starting product for the top layers as simple as possible Manufacture shredding device.

In order to produce such fiber chips, one proceeds according to the invention from a flat chip of normal thickness (approx. 0.2 to 0.4 mm) produced with a conventional chipper. These flat chips are made by means of a shredding machine commonly used in the paper and pulp industry, a so-called refiner, whose working organs are shredded however, have undergone various changes. This well-known shredder a technically related production area had to be equipped with special shredding segments that If possible, shred the material only in terms of its thickness and width, while the length of the fiber chips produced in this way is about 5 mm on average.

The transport of the chips to the shredding segments within the machine caused further difficulties. For this was found a certain form of the so-called substance maturer, which also ensures a smooth and blockage-free flow through the machine in the event of short-term intermittent loading of the machine.

In the course of the experiments it was also found that it is advisable to use the starting material for the further comminution process to add 30% water (based on absolutely dry wood), whereby it - apart from the appropriately performed shredding - succeeds in dissipating the frictional heat that occurs during shredding. Forest freshness or even very damp wood does not need such an addition of water.

With the help of this shredding machine reminiscent of a so-called "refiner" the wood fibers required according to the invention for the outer layers are obtained, which are dried and sieved with a certain mesh size or by wind sifting of possibly entrained

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Coarse particles and unwanted dust particles are freed. Coarse parts can run through the shredder again. This fiber » Chips have a noticeably uniform structure.

This material can be bunkered and glued without matting or lump formation; its mechanical behavior corresponds to im essentially that of the wood chips. The material can be spread in known spreading machines. As a result of the uniform structure of the Fiber chips need not be feared of segregation.

Its own weight, which is higher in relation to the fiber, gives the material enough sinking speed to keep it at normal Fluctuating basis weight distribution with a uniform layer thickness on a base. When spreading, the Chip fibers in a well felted state on top of each other. On the other hand, since there is a low volume weight, it becomes equivalent Layer thickness on both sides of the panel core, i.e. the cover layers, achieved without difficulty. Own the panels so produced an extremely low susceptibility to delay.

Due to the length of the chip fibers, sufficient lifting and transverse tensile strength is achieved even with the normal addition of synthetic resin. The flexural strength of the panel has been significantly increased thanks to the good interlocking of the material of the cover layers. A middle one The flexural strength of the chipboard according to the invention can already achieve the values required in the DIN regulations with a lower gross weight reach. The surface achieved by using wood fibers swells considerably less when exposed to water and solvents, due to the lower thickness of the material, and more homogeneous, due due to the uniform fiber thickness. The closed surface allows you to use the glue you need when gluing with veneers, foils, etc. To reduce the amount of glue, which also destroys the swelling influence.

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Claims (3)

A'10 48g - 7 - Γΐ. η One or both sides provided with a top layer made of wood fibers Chipboard, characterized in that the wood fibers used for the cover layer have an average fiber length of about 5 mm and a diameter below 0.1 mm. 2.) Particle board according to claim 1, characterized in that the Wood fibers used to produce the outer layers have a degree of slenderness (ratio of diameter to length) from 1 in 50 to 1 in 200. 3.) A method for producing chipboard according to claim 1 and / or 2, characterized in that the chip fibers on a modified refiners of known design are produced. 009812/1070