DE1229284B - Process for the production of wood chips with reduced water absorption and swelling capacity - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. C ...

B29j

German class: 39 a7- 5/00

Number: 1229 284

File number: B 733881 c / 39 a7

Filing date: September 5, 1963

Opening day: November 24, 1966

Attempts have already been made to determine the water absorption and swelling capacity of wood chip workpieces, in particular Chipboard, by adding water repellants such as hard and soft waxes suppress. In these known processes, about 0.25 to 1.5% of the water repellent is generally used, based on the dry weight of the wood chips in the manufacture of the panels. However, the effect achieved is only moderate. Are you giving larger amounts of water repellent, for example 5%, the water absorption and swelling capacity can be further reduced, however this process could not establish itself in technology.

It has also been proposed to use wood chip workpieces, such as chipboard, by extending them the pressing times and to make water-resistant by increasing the pressing temperatures. These methods However, they have serious disadvantages because not only higher energies are consumed, but because the wood chips in the upper layers of the panels are partially due to the greater stress hydrolytically decomposed ("keratinized") and discolored. The technological characteristics of the this kind of preserved chipboard is not good.

It is also known to reduce the water absorption and swelling capacity of chipboard by that after removal from the press, the chipboard is subjected to a thermal aftertreatment undergoes special heating chambers. Here are the plates, either immediately or after previous Heating to about 140 ° C, exposed to a 160 to 220 ° C gas stream. Even with these procedures In most cases, keratinization of the plate surface cannot be avoided. In addition, there is the risk of the plates igniting if no oxygen-free gas flows are used, which in turn requires considerable technical effort.

In the case of the processes described, the effects of high temperatures result in the good technological properties of wood e.g. B. the ■ flexural strength changed in an undesirable manner. In addition, temperatures above 140 ° C. have an adverse effect on the properties of the binders used.

It has now surprisingly been found that, without the disadvantages described above, wood chip workpieces, such as chipboard, based on reduced water absorption and swelling capacity of wood chips and, if necessary, others suitable for the production of wood chip workpieces Comminution products of vegetable raw materials.

Process for the production of
Wood chip workpieces with reduced
Water absorption and swelling capacity

Applicant:
Aniline & Soda Factory in Baden

Aktiengesellschaft, Ludwigshafen / Rhein

Named as inventor:

Dipl.-Ing. Dr. Werner Helmut Clad,
Helmut Henkel, Ludwigshafen / Rhine

binding agents and water repellants by mixing or spraying the chips with the Binding agents and waterproofing agents, forming a raw package and pressing in the heat in itself well-known Wej & § can be produced by using the Wood chip workpieces after pressing a thermal aftertreatment at one temperature above the melting point of the water repellent up to a temperature about 60 ° C higher subject.

The hard or soft wood chips, fiber bundles, Use flax shives, coconut fibers or similar material. It can also be synthetic high molecular weight Comminution products such as expanded polystyrene can also be used.

The natural or synthetic glues commonly used in the wood industry, such as Urea-formaldehyde, melamine-formaldehyde or phenol-formaldehyde resins, e.g. B. Hydroxybenzene formaldehyde or R ^ sprcinformaldehyde resins, sulphite waste liquor or mixtures of such binders, for example Mixtures of urea-formaldehyde resins with a high proportion of formaldehyde, together with Melamine, in question. The binders are, if necessary, the usual hardeners, in the case of formaldehyde z. B. ammonium chloride added.

In the context of the invention, water repellants are natural or synthetic hard and soft waxes such as paraffin, ozokerite, montan

609 728/318

3 4

wax, polyethylene and polypropylene, preferably The plate produced according to the invention has the following

with a melting point of at least 40 ° C, other properties shown in Table I:

stood. The water repellants are labeled with _T

With the help of the input table I

directions as a melt or, as a dispersion to the flexural strength of 280 kg / cm ²

Hok shavings sprayed on. . . . Transverse tensile strength .... 8 kg / cm ²

The inventive method Is for ^ö
wise carried out in such a way that one can detect the swelling of the thickness
The press coming, still, hot chipboard with 2 hours of water in an insulating layer, which, for example, from storage 0.5% of the thickness in

Foam polystyrene is made, surrounds or that one has the dry state Bringing plate into climatic rooms. As climate rooms can

air conditioning ducts are used in the continuous process. For comparison, one was used as described above. If necessary, especially when the board is produced, which does not take several days of thermal treatment after the thermal treatment, but rather takes up to room temperature after pressing, the required amount of heat will be cooled. Their properties are based on a stream of hot air. The wooden from Table II emerges,
Chip workpieces are, for example, a few days after pressing, in the case of urea formal- Table II
dehydrating resins at about 60 to 8O ⁰ C, in the case of 20

Phenol-formaldehyde resins at about 70 to 100 ° C. Flexural strength 250 kg / cm ²

stores. After the thermal treatment, the “ _ft ·, · ,. ",,,
Wood chip workpieces are air-conditioned as usual. In many transverse tensile strength .... 8 kg / cm ²
In cases it is not necessary to swell in thickness after pressing
To add heat, it is sufficient if the 25 2-hour water-hot wood chipboard workpieces are stored at 7.2% of their thickness in order to prevent them from cooling down

well insulated and left lying in the pile. dry condition

The main advantages of the process according to the invention over the known processes are in Example 2
in that in this way water absorption and 30 3800 parts of softwood chips (laboratory test chips) who-swelling capacity of the wood chip workpieces suppresses the with 45 parts of paraffin (melting point 52 ° C) can be without the other Eigen- no ° C under a pressure of 110 atmospheres which are used for the manufacture of these products in the best possible division and distribution. The deten raw materials changed disadvantageously. Chips are then made with 750 parts of a 40% strength

The swelling in thickness of the 35 aqueous solution of a phenol-formaldehyde condensate

MAESSEN method chipboard pieces obtained _sa ts in a mixing device at room temperature

lies z. B. 40 to 95% lower than the thickness nozzle. The chip mixture becomes a raw plate

swelling of the ling produced by known processes. The cake is baked at 175 ° C for 8.5 minutes

Wood chip workpieces. The thickness swelling is in ° / o th long under a specific pressure of

the thickness of the swelling test body according to DIN (52360, 40 25 kg / cm ² pressed to a 19 mm thick plate.

52361, 52364, 52365, 68761) measured. To reduce heat dissipation, the

The parts mentioned in the following examples plate with a shell made of expanded polystyrene

and percentages are given unless otherwise stated. The required amount of heat is provided by

Weight units. Hot air heating supplied, in such a way that on

Example 1 "J-TJj ^

3000 parts softwood chips (lab test chips) advertising ³ · ^Ta g 90 ° C

the one with 20 parts paraffin (melting point 52 ° C) at the 4th day 85 ° C

110 ° C under a pressure of 110 atü under 50 5th day 70 ° C

best possible division and distribution. Which are sustained.
Chips are then made with 500 parts of a 50% strength

aqueous solution of a urea-formaldehyde condensate ¹ ^ plate produced according to the invention has M-

sats (molar ratio of urea to formaldehyde 1: 1.8) S ^ende > properties shown in ^{Table 1,}

and an aqueous solution of 4 parts of ammonium

chloride and 5 parts of a 25% aqueous am- _. , ... _ ",,

monia solution in a mixing device with room flexural strength ....... 270 kg / cm ²

temperature under a pressure of 3 to 5 atmospheres transverse tensile strength .... 7.15 kg / cm ²

showered. The chip mixture becomes a raw plate thickness swelling after

ling shaped. The cake is at 165 ° C for 7 minutes ₂ So _Stu ^ _the ^^

long under a specific pressure of j _{o? o / o der Dic} none

25 kg / cm ² pressed into a 19 mm thick plate. 00>

T ^ - τ «u -jj it, t» .iv_ c ™, · ™ n π dry state

The plate is heated to 60 to 80 ° C by ventilation

chilled. This temperature is then held for 4 days. For comparison, as described above, one

upright for a long time by making the plate against cooling.

treatment is through a jacket made of expanded polystyrene, but after pressing to room temperature

protects and the required amount of heat has been cooled by temperature. Your properties are running out

Hot air heating supplies. Table II.

Table II

Flexural strength 270 kg / cm ²

Transverse tensile strength 7.25 kg / cm ²

Thickness swelling after 2 hours of immersion in water 6.35% of the thickness in

dry condition

Claims (1)

Claim: Process for the production of wood chip workpieces with reduced water absorption and swelling capacity on the basis of wood chips and, if necessary, other comminution products suitable for the production of wood chip workpieces of vegetable raw materials, binders and water repellants by mixing or jetting the chips with the binders and water repellants, forming a blank and pressing in the heat in a known manner, characterized in that the chipboard pieces after compression to a heat treatment up to about 6O ⁰ C higher temperature are subjected to a temperature above the melting point of the hydrophobicizing agent. Considered publications:
German Auslegeschrift K 17286 IV a / 38 h (published on October 27, 1955). Legacy Patents Considered:
German Patent No. 1154 928. 609 728/318 11.66 © Bundesdruckerei Berlin