DE884274C - Process for the production of wood fiber boards - Google Patents

Description

Process for the production of wood fiber boards The invention relates to a process for the production of wood fiber boards from lignocellulose-containing fibrous Fabrics. These substances, e.g. B. wood fibers are heated as a wet sheet between Press plates pressed. A certain amount of moisture is necessary for the sheet to be able to bind of the fibers during the dull pressing process. Although one has tried completely to press dried fiber sheets. However, no favorable result is obtained here, because the fibers are very stiff when dry and have no binding capacity have more. The panels produced are too loose and therefore unusable. Man could by using extraordinarily high pressures and temperatures, too compress the dry, stiff fibers together so that they have the desired final shape maintained. But this would become a very cumbersome and uneconomical one Conduct proceedings.

For this reason, extremely wet sheets have hitherto been pressed. Usually this does not mean any disadvantages. It can, however do not produce press plates that are smooth on both sides directly in the press. While During the pressing process, the water previously present in the arch must escape by evaporation. If both press plates are completely smooth, the water can initially emerge to the sides, but as the compression progresses The water can no longer find a way to the outside of the plate, so that it is inside the Plate remains and the plate produced is therefore unusable. It must therefore be on a sieve cloth can be attached to one side of the plate to be pressed. In In this case, the water can be distributed over the entire surface of the plate in the sieve cloth penetrate and, if necessary, escape laterally through the cloth. The sieve presses due to the high pressures in the plate -ein, so that the finished plate on one side has a plastic impression of the fabric of the screen cloth.

It is now very desirable for many purposes to make panels that are flat and smooth on both sides. This applies e.g. B. for door panels, etc. The invention is based on the knowledge that this object can be achieved by replacing the water otherwise contained in the fiberboard with an 01. This oil, which is added in the order of 15, preferably 3 to 10 parts by weight, must. the. Have the property that it is at the usual plate pressing temperatures, for. B. at 130 to 23o ° ,. is practically non-volatile and can also, when pressed, effect the elasticity and the binding capacity of the practically dry fibers. With the carried out. The following oils were found to be suitable for tests: Chinese wood oil, linseed oil (expediently blown), oiticica oil.

It is known per se to work with oils, resins, etc. in the production of panels of the most varied types. It is Z. B. a wood fiber resin mixture with at least 430/0 and preferably 100% resin has been used. Such an addition of resin is extremely high, so that the economic viability of the process must be complained about. In the context of the present invention, resin does not seem to be applicable, because it has been found that, for. B. 1 5 0/0 resin as a binder are not sufficient to achieve a favorable result.

Very large amounts of additives are also added in other processes. So was z. B. applied an impregnating agent in such amounts that the resulting porous, dried molded fibrous material is impregnated through and through. The impregnation agent should in this case round: 7.5% of the molding, so that it is only about 25 Contains 0/0 fibers.

In other cases attempts have been made to put completely dry plates in to bring in the press, emphasizing that the fiberboard before the Bring in must have a temperature that is equal to or higher than that of the Pressing tools is. So the suggestion is not made here as a plasticizing agent to add an oil. In other processes, drying oils are used. But In these cases, too, these drying oils should not use up the otherwise existing water replace in the sense of a plasticizer.

In another case, certain chemicals were added which are in Ingredients found in cellulose fibers, such as hemi-cellulose, pectin, wood gum and Protein, attack and trigger. Whether this creates a better bond between the Fibers obtained must be doubted. In any case, this procedure should the water as a plasticizer cannot be replaced, because it was expressly stated indicated that the fiber sheet pressed in the moist state from an aqueous wood pulp should be.

In another method, textile products, e.g. B. insulating sleeves for heat conduction pipes, pads for linoleum carpets, etc. .. The fiber material -were binders, plastic materials, protective materials or the like. Added. Then the mass was still with a liquid or a Solution soaked. After squeezing off the excess liquid, the mass was molded and exposed to heat or vulcanized. This method also does not convey the knowledge when pressing hardboard to replace the water with 0l as a plasticizer.

Another procedure should be done so that, ß water provided only in a small amount, referred to as the normal amount of moisture in the fiber should be. Even this amount of moisture is too high for steam to form during to prevent hot pressing. Therefore, in this case, it had to be a time-consuming one Operating mode of refuge can be taken. Before the pressing pressure on the finished pressed Fiberboard stopped, the press plates had to be at a temperature below 100 ° be cooled down.

In other cases were. hardenable synthetic resins and drying oils for Painting or impregnation of a fibrous product used.

In the manufacture of insulators, it is also known to use an impregnation to be carried out under vacuum and increased heat. This removes the moisture from removed from the fibers, and if the impregnating agent (paraffin) is then added, the impregnation of the fibers occurs.

In addition, it has already been proposed to glue several cardboard layers to connect with each other and then to paint the product with oil. Included the cardboard could also be treated in an oil bath under pressure. Then one followed Air drying and finally gluing the individual together. Panel. Here is a treatment of finished panels is provided while the invention is based on the addition Obtains oil as a plasticizer before pressing.

When compressing cellulose fibers, it has also become known Add urea or thiourea .. This should only allow the pull and Breaking strength can be increased.

Furthermore, 01 has been added in the production of Plattext to give the surface a linoleum-like texture so that the board z. B. can be used as a floor covering. It cannot be inferred from this either that the water used as a plasticizer can be replaced by an oil.

Finally, one has in the production of moldings, in particular thin-walled products, a felted, fibrous wet sheet soaked with alcohol, treated with a binder, such as a synthetic resin, the product impregnated in this way dried and hot pressed under high pressure.

When producing pulp moldings, you have the floodwater in whole or in part organic solvents, in particular aliphatic hydrocarbons, for the plastics added to the pulp, z. B. synthetic resins replaced.

In contrast to all these proposals, the present inventive concept can be seen in the fact that the replacement of the water in the pulp consists of an oil which, at the usual Plattenpreßeinperaturen, z. B. at 130 to a30 °, is practically non-volatile and has the property of maintaining the elasticity and the binding capacity of the practically dry fibers when pressed.

The additive according to the invention, which can be used on its own or in combination with other additives, can be added to the pulp before dewatering and mixed with it, or added to the already formed fiber sheet before or after complete drying. It is only important that a 0 o e ichmäßige distribution is obtained of the additive used so that he has opportunity to interact with all the fibers. In general, the additive can be added at any time prior to pressing.

According to one embodiment of the invention, one can use a slurry of the fibrous, lignocellulosic material in water, the or those in question add standing substances, then drain the fiber mass and, if necessary, z. B. in a roller dryer, and dry them afterwards the linwirlcung of heat and apply pressure.

Another method is to make a water slurry prepares a fibrous, lignocellulosic material, forms it into sheets, drains, dries, adds one or more of the substances in question and exposes the arch to heat and pressure.

The hot pressing is advantageously carried out in a multi-layer press in which each sheet of mass is surrounded on both sides by flat pressing surfaces. The pressing temperature is usually 130 to 230 °, for example 170 to 20 °, and the pressing pressure 40 to 150 kg / cm =, preferably 85 kg / cm * -.

An advantage is often achieved by using one of the specified Oils, e.g. B. with Chinese wood oil, glued and dried in a roller dryer plate is subjected to further heating prior to pressing. to a partial To achieve polymerization or oxidation of the added oil before pressing. This heating is expedient in the presence of an oxygen-containing agent, z. B. air executed. The air can e.g. B. sucked or blown through the plate will.

You can continue the hardening of the oil even after the pressing is finished, by the plates for some time exposure to a heated gas, for example Air, to be subjected. This gives a further improvement in quality the plate.

In order to achieve the best possible quality of the panels, the finished pressed, expediently on both sides flat or smooth plates in a bath of one or several of the above oils, e.g. B. Chinese wood oil, dipped or with it be painted, which increases the oil content of the plate. After one of those Supplementary Gberzug with the relevant means should affect the panels exposed to an agent which has the ability to treat the surface layers thus obtained to harden, e.g. B. by polymerization or oxidation, this means from hot Air can exist.

The amount of oil added in this way should be 5 to 15% of the weight of the plate so that the plate has sufficient strength and water resistance receives. Example i A slurry of lignocellulosic pulp in 1 to 15%, preferably 5%, of Chinese wood oil are added to water. The fiber is dewatered in a bakännter way on a Fourdrinier wire and the wet fiberboard formed dried in a roller dryer to complete dryness. While the Plates are still warm, they are put into a press and cooked for 10 minutes at a temperature of from 14o to 20 °, preferably at 1.95 °, and a pressure of .to up to i 50 kg / cm ° - pressed. Example 2 A fibrous, lignocellulose-containing pulp suspension is dewatered in the usual way and completely dried in a roller dryer. Chinese wood oil is concentrated on the dry and poor plates or diluted form and in amounts from 1 to 15, preferably 5% of the dry fiber weight applied. The plates are pressed in the manner indicated in Example i.

The invention also includes the products made according to it. It also includes embodiments in which when pressing on one side or a sieve cloth is used on both sides of the sheet to be pressed. In this Trap, the panels can be planed or polished afterwards.

The product made according to the invention generally has a specific gravity of about i, which in certain cases depends on the added Substances can be up to 1.5.

It goes without saying that one can also use the oils mentioned per se instead Use other oils that are described under the existing working conditions in oils Type pass or result in such substances with other substances.

Furthermore, is the one occurring in the description and in the claims Expression "an oil that can be used at normal platen press temperatures, e.g. B. at 13o to 23o °, is not volatile or not volatile to a significant extent and has the property, to preserve the elasticity and the binding capacity of the fibers during pressing «so to understand that it includes all oils now known or discovered in the future, which is a pressing of the plates in the described type in the absence of water and regardless of the pressing temperature, without the plates are charred during pressing. The pressure at pressear can fluctuate in any way or be kept unchanged.

Claims (7)

PATENT CLAIMS: i. Process for the production of wood fiber boards made of fibrous materials containing lignocellulose, characterized in that the practically anhydrous starting fiber material under the action of heat and a pressure of at least 40 kg / cm2 with a maximum of 15, preferably 3 to 10 parts by weight of one Oil is pressed, which at the usual plate pressing temperatures, for. B. at 13o to 23o °, practical. is not volatile and has the property when pressed To preserve the elasticity and the binding capacity of the practically dry fibers, z. B. with one or more of the following. Oils: Chinese wood oil, linseed oil (useful blown), oiticica oil. 2. The method according to claim i, characterized in that da.ß a water slurry of finely divided lignocellulosic pulp at most 15%, expediently 3 to 10%, based on the dry weight of the lignocellulose-containing Substance, adding one or more of the oils specified in claim i, the mixture forms into arcs, the water practically completely removed and,; the arcs between heated. Pressing organs. 3. The method according to claim i or 2, characterized in that that a water slurry of lignocellulosic pulp is prepared, forms them into sheets, dehydrates, optionally dries one or more of the adding the oils concerned and then subjecting them to the action of heat and pressure. 4. The method according to claim i to 3, characterized in that. that the pressing temperature 13o to 23o °, for example from 170 to 21o °, preferably from 180 to 20 °. 5. The method according to claim i to 4, characterized in that the pressing pressure is 4o to 150 lcg / cm2, for example 7o to roo kg / cm2, preferably 85 kg / cm2. 6. The method according to claim i to 5, characterized in that the or the relevant oils are applied to the formed fiber sheet before it is completely dry, whereupon the drying and pressing is carried out. 7. The method according to claim i to 6, characterized in that the one or more oils concerned, for. B. with Chinese wood oil, glued sheets after dewatering, but is subjected to further heating before pressing, expediently in the presence of an oxygen-containing agent, e.g. B. air, preferably by sucking or blowing air through. The like. For the purpose of obtaining a prepolymerization, pre-oxidation or other preparatory curing reaction of the substance in question before pressing. B. The method according to claim i to 7, characterized in that the wood fiber board after completed hot pressing the action of a heated oxygen-containing gas, for. B. air, for a suitable time to continue the hardening of the oil. G. A method according to claim i to 8, characterized in that the finished pressed plates are immersed or coated with a bath of one or more of the oils specified in claim i and then subjected to the action of an agent, e.g. B. hot air, which has the ability to harden the surface layers thus obtained, for example by polymerization or oxidation. Cited pamphlets: Brandenburger, Production and Processing of Kunstharzpreßmassen, Volume IV (1937), Appendix pp. 165 to 185; German Patent Nos. 2o 592, 388449, 418304, 456593, 500355, 5o6 60o, 607978, 618 369, 631 342, 653 994; French Patent Nos. 676 072, 751 973, 783 474; Swiss Patent No. 163 562; British Patent Nos. 164 620, 329: 273, 354 001; U.S. Patents Nos. 256 872, 1 131 86o, 1268034 1465544 1680408, 1705 090, 1809316, 1856946, 188o930, 1901930, 1941536, 2028738,: 203o6.25,: 2044213, 2.2o689: 26, 2134 659, 2143 831 ,: 2: 2 15 244.