DE1256407B - Process for the production of wood fiber boards of great hardness - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

PATENT LETTERING

Int. Cl .:

C08d

B 27 k

German Cl .: 39 b-4/01
38h-2/01

Number: 1256407

File number: B 75759IV d / 39 b

Filing date: March 6, 1964

Open date: December 14, 1967

Issue date: June 27, 1968

The patent specification corresponds to the patent specification

There are already known processes for the production of wood fiber boards, in which boards with hard and smooth surface. The known plates have high strength and resistance against moisture. In one of these processes, the still moist wood fiber boards are removed from the Presses treated with natural oils such as linseed oil or tall oil. However, this method has the disadvantage on that the wood fiber boards do not separate properly from the press plates used in the pressing leave. In another known method, alginic acid or cellulose derivatives are therefore added (German Auslegeschrift 1156 233), which prevents sticking to the press plates. The after However, fibreboard obtained by this method is poor in strength.

Another known process for the production of wood fiber boards, in which the surfaces of the finished dry boards are impregnated with linseed oil, is also unsatisfactory. A disadvantage of this process is seen in the relatively long drying times of about 6 hours at temperatures of 160 to 17O ⁰ C, under which suffer profitability.

Furthermore, from the German patent specification 926 810, a method for the production of synthetic resins is carried out thermal copolymerization of aromatic polymerizable Coke oven light oil containing monomers with cyclopentadiene and unsaturated fatty acids and their derivatives are known. Resins of this type can also be used, among other things, for impregnating wood. As a result of the relatively high proportion of polar groups, wood coatings produced with them exhibit however, has insufficient water resistance for practical use.

The disadvantages outlined are intended to be avoided with the aid of the claimed method.

The invention relates to a method for producing wood fiber boards of great hardness Impregnation of the fibreboard with oils and then Heating, which is characterized in that, for the impregnation, hardenable, oily butadiene homo- or Butadiene-StyroUMischpolymerisate used.

The oily polymers used have molecular weights from about 500 to 20,000, preferably from 1,000 to 10,000.

By treating with the crfmdiings according to the polymers using the wood fiber boards' for example flexural strengths, -50 to 200 "/ ,, are larger than with iiiibeliamlelteii plates. 'Other- I igensclial'k'ii are also considerably better procedures to manufacture

of fibreboard of great hardness

Patented for:

Aniline & Soda Factory in Baden
Aktiengesellschaft, Ludwigshafen / Rhein

Named as inventor:

Dr. Herbert Müller, Frankenthal;

Dr. Hubertus Seibt, Ludwigshafen / Rhine;

Dr. Erich Kühn, Ziegelhausen;

Otto Wittmann, Ludwigshafen / Rhine

sert, e.g. B. the swelling behavior, the water resistance, the weather resistance and the resistance to bacteria and mold growth as well as paint adhesion.

A particular advantage of the method according to the invention over the previously known method consists in the relatively short curing times at low temperatures. In the method, is obtained already with impregnations of about 50 g / m ² and about 1 to 2 hours of heating at 120 to 13O ⁰ C fibreboard, their bending strength is improved compared to untreated panels by 70 to 100%.

Suitable oily butadienes are those which are at least 60, in particular at least 85, mol percent 1,4-linkage and at least about 30, in particular at least 60 mol percent cis-1,4-configuration.

But also oily butadiene polymers, which contain the butadiene predominantly in 1,2-linkage, are suitable e.g. B. oily butadiene polymers produced by means of sodium with a K value of 32, or oily Copolymers of butadiene with styrene or (X-methylstyrene, which, for example, using anionic Polymerization catalysts have been obtained.

Oily butadiene polymers, which have been prepared using boron trifluoride or complex compounds of boron trifluoride, such as BF ₃ · 2 H ₂ O, BF ₃ · 2 CH ₃ OCH ₃ and BF ₃ · 2 CH ₃ OH, as a catalyst, are also very suitable .

Oily, drying butadiene polymers, which are chemically inodified, are particularly suitable for the process. z. B. at elevated temperature (100 to 200 ° C) have been isomerized. Such polymers are particularly reactive and dry quickly. As a catalyst

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Gates for the isomerization are preferably small amounts of transition metals of VI. to VIII. Group of the Periodic Table of the Elements and / or compounds in which these metals are in zero-valued state can be used. Examples of suitable isomerization catalysts are iron pentacarbonyl, iron carbonyl hydrogen, iron tetracarbonyl, di-iron acarbonyl, nickel (o) -bis-cyclooctadiene- (l, 5) and cobalt tetracarbonyl. The oily isomerized butadiene polymers harden particularly quickly in the air. The curing times are about five to fifteen times shorter than for non-isomerized ones Polymers.

The oily, reactive polymers used in the process can also contain up to 50 percent by weight other polymers that cannot be further polymerized, such as polystyrene, polycyclopentadiene or polyacrylonitrile, included mixed in. In addition, the butadiene polymers can be polymerizable monomers Compounds such as styrene, acrylonitrile or acrylic acid and their esters, maleic acid and their derivatives, as well as cyclopentadiene or dimeric cyclopentadiene, may be added.

The butadiene polymers can also be mixed with drying natural oils such as linseed oil, soybean oil, and / or drying oils with conjugated double bonds, such as wood oil, tall oil, oiticica oil, or isomerized.m linseed oil, mixed or modified in deficit.

For better drying properties, the oily butadiene polymers can be treated with air or pure oxygen, optionally in the presence of a diluent or solvent, has been oxidized being. The oxidation can, for example, optionally be carried out by blowing air or oxygen into the polymer in the presence of oxygen-transferring agents such as organic salts of cobalt, Iron, lead or manganese. Naphthenates, caprylates and oleates of these are particularly suitable Metals used in amounts from 0.01 to 3%.

A substantial acceleration of drying, e.g. B. about two to ten times, can also be achieved are made by using oily butadiene polymers, which are produced by the addition of v-ethylenic unsaturated mono- or dicarboxylic acids and / or their derivatives, for example of maleic acid, Maleic anhydride, chloromaleic anhydride, fumaric anhydride, Acrylic acid and acrylic esters. This is maleic anhydride preferred for its great responsiveness.

In the claimed process, the curable oily butadiene polymers can contain from 1 to 50, preferably 3 to 20 percent by weight of ethylenically unsaturated groups which act as crosslinkers Connections mixed up. As crosslinkers for the oily polybutadienes with 1,4-linkage come for example polybutadiene with predominantly 1,2-linkages and copolymers of butadiene with styrene or a-methylstyrene, octadiene (1,7), octatriene (l, 3,6), 3-methylheptatriene (l, 4,6), cyclopentadiene and dimeric cyclopentadiene, in which the predominant Amount of butadiene incorporated under 1,2-Additiort is in question. Such high molecular weight crosslinkers generally have molecular weights from 500 to 10,000.

The drying time, which is greatly reduced by the use of particularly reactive oily butadiene polymers, can can still be reduced by adding radical-forming compounds such as peroxides and azo-bis-carboxylic acids or their derivatives, such as azo-bis-butyric acid nitrile, or heavy metal compounds, optionally together with peroxides, added.

The usual siccatives, such as salts of cobalt, iron, lead and manganese, e.g. B. the naphthenates, Caprylate and oleates have an accelerating effect. They are expediently in amounts of 0.01 to 5 percent by weight, preferably from 0.1 to 3 percent by weight.

The modifications and additions described can be made before or during the manufacture of the wood fiber boards respectively.

The curable oily butadiene polymers are either in the diluted state or together with Suitable solvents or thinners are used to impregnate the wood fiber boards. As a solution or diluents are straight-chain or branched aliphatic hydrocarbons, especially with more than 5 carbon atoms, cycloaliphatic, araliphatic or aromatic Hydrocarbons, such as gasoline fractions, cyclohexane, benzene, toluene, xylene, isopropylbenzene, also aliphatic or aromatic halogenated hydrocarbons, such as tetrachloroethane, trichlorethylene and chlorobenzene. The amount of solvent is not critical and can be e.g. B. up to 1000 percent by weight, based on the butadiene polymer used amount.

The oily butadiene polymers can also be used in the form of aqueous emulsions. the Any siccatives or peroxides to be used can already be added to the butadiene polymer added to the preparation of the emulsion, but it is also possible to add water-soluble siccatives only after Mix in preparation of the emulsion. The concentration of the butadiene polymer in the emulsion can be varied within wide limits. In general, emulsions are used whose content of Polymer between 10 and 70 percent by weight, preferably between about 20 and 50 percent by weight, located.

The treatment of the wood fiber boards with oily butadiene polymers is expediently carried out by applying them to already dry and pre-pressed wood fiber boards. The fiberboards can be impregnated in a known manner by spraying, dipping or rolling the oily butadiene polymers or their solutions or aqueous emulsions. The curing of the polymers can take place by drying the plates at room temperature in the air. However, suitably the plates are at higher temperatures, for example ⁰ to 200 C, preferably at 80, heated to 15O ⁰ C, whereby the curing process accelerates significantly. In general, curing times of about 30 minutes to 3 hours are then sufficient. However, even shorter curing times lead to wood fiber boards with improved properties.

By storing the plates treated according to the invention for several hours at an elevated temperature, their properties, e.g. flexural strength, swelling behavior, water resistance and surface hardness, can be further improved.

A modification of the claimed process consists in the treatment of not yet pressed, predried Fibreboard with oily butadiene polymers, whereby in a similar way to the above

pressed fiberboard. After the oily polymers have been applied, an optional one follows inserted pre-drying the actual hardening at elevated temperature that occurs with the pressing process carried out together and, if necessary, after the pressing by prolonged heating is terminated.

In addition, the oily polymers can also be impregnated in the form of aqueous emulsions can be applied to the wet wood fiber webs. Drying, pressing and heating of the treated Fiber webs can optionally be done in one operation, which is also followed by an additional Post-curing follows.

For the following examples, 4 mm thick wood fiber boards with a flexural strength of 330 kg / cm ² measured in accordance with DIN 52352 were used. The parts given in the examples are parts by weight.

B e i s ρ i e 1 1

Dust-free wood fiber boards were treated with an oily butadiene-styrene copolymer composed of 20 parts of styrene and 80 parts of butadiene with a K value of 23, to which 2 parts of cobalt naphthenate were admixed per 100 parts. The panels were impregnated using a roller glue application machine without rubber profiling. To achieve uniform impregnation, the polymer was warmed to 60 to 70 ⁰ C. The necessary heat was supplied through the heatable rollers of the machine or by pumping over a heat exchanger. By regulating the distance between the rollers, an application rate of about 60 g / m ^{2 was achieved} on the smooth sides of the fiberboard; Somewhat higher application quantities on the sieve sides of the fibreboard could not be avoided under these conditions.

The treated plates were then ^{cured at 150 °} C. for 2 hours. The hardened, dark brown plates had a flexural strength of 530 kg / cm ² .

B e i s ρ i e 1 2

Wood fiber boards were treated by briefly immersing them in a bath which had the following composition: 58 parts of butadiene-styrene copolymer (as in Example 1), 1 part of cobalt naphthenate and 40 parts of trichlorethylene. After briefly draining, the plates were ^{hardened in a drying tunnel for 2 1} ₂ hours at 125 to 130 ° C. The plates then had a flexural strength of 515 kg / cm ² .

Example 3

Wood fiber boards were on a continuously running belt with a polymer solution of the im Example 2 mentioned composition sprayed. Both with EinöfTdüsen only with pressure and it is also possible to work with two-fluid nozzles with compressed air. The nozzles were about six to eight inches from the Plate surface removed. When using a compressed air nozzle, a working pressure of approx 3 atü as cheap.

60 to 100 g of polymer solution were used per square meter applied. The plates treated in this way were placed in a drying chamber at 130 ° C. for 2 hours heated. They then had a flexural strength of 527 kg / m *.

B e i s ρ ie I 4

Wood fiber boards were impregnated by applying 100 g / m ^{2 of} a mixture of 60 parts of an isomerized oily copolymer and 40 parts of xylene on a commercially available film casting machine. Subsequent curing for 2 hours at 130 ° C. gave dark brown wood fiber boards. obtained with a smooth surface, which had the flexural strength -496 kg / cm ² .

The isomerized oily copolymer was obtained by heating a mixture for six hours

a) 99 parts of a copolymer of 20 parts of styrene and 80 parts of butadiene with a K value of 23 and

b) 1 part of iron pentacarbonyl at 170 ° C. has been obtained.

Claims (3)

Patent claims: L Method of manufacturing fibreboard of great hardness by impregnating the fibreboard with oils and subsequent heating, characterized in that one curable, oily butadiene homo or butadiene styrene copolymers are used for impregnation. 2. The method according to claim 1, characterized in that that such Butadienpolynicrisate are used, which by isomerization under Use of small amounts of transfer metals the VI. to VIII. group of the periodic table of the elements and / or of compounds fertilize, in which these metals are present in the neutral state, after heating to temperatures between 100 and 250 ° C have been obtained, 3. Process according to Claims 1 and 2, characterized in that such butadiene polymers which contain siccatives are used. Considered publications:
German patent specification No. 926 810.