FI73717C - Semi-dry formaldehyde-free method of making chipboard. - Google Patents

Description

7371 7

Semi-dry forma1dehyde-free particle board manufacturing process.

Halvtorr formaldehyde method is used in the form of a spatula.

The present invention relates to the manufacture of particle board in which water-soluble formaldehyde-containing resins are not used as the adhesive. The object of the invention is to produce a particle board made of wood fibers, which are first slightly moistened with air 11a and a dry binder is added, by heat pressing into a board of suitable thickness.

At present, particle board is made from wood fibers of various lengths, the adhesive 60% ureaforma 1 dehyde aqueous solution is sprayed into a cylindrical rotating drum with a certain number of wood fibers. Press in a hot press into a plate of approx. 150 - 180 C. Other adhesives can also be used, such as amine formaldehyde, phenol formaldehyde. The latter resins are expensive and their use is limited to various moth purposes. All of these resins are well known. According to the invention, crosslinked polyethylene in the form of a powder premixed with tertiary butyl peroxide or vinyl isane is used to bind the wood fibers, from which the peroxide crosslinks the polyethylene at a temperature of 125 to 180 ° C, while the vinyl silane also needs water to bind.

Polyethylene crosslinking has two different effects when gluing wood fibers. The sizing properties are improved because the crystal structure of P E changes and at the same time the heat resistance is improved.

According to the present invention, the particle board is manufactured as follows because the binder is a dry crosslinkable polyene.en powder, it cannot be made to adhere to wood fibers except by using a mixer of the Papenmeier type at a speed of about 1000 rpm, in addition to a small amount of soy powder. , dissolved in 20% maleic acid cycloolefin ammonia-water solution to a 10% solution, or Soy powder is dissolved in water to which a small amount of ca 1 silmic acid (CalOH) has been added. Other types of s i äk n n ta rt un t a a ι ne i ta can be used. When the above-mentioned solution is mixed with the wood fibers, it forms an adhesion surface, and the PE powder is caused to adhere homogeneously to the surface of the wood fibers in a high-speed mixer. So i j a 1 i uok se 1 1 a there are also two other things that can be done when it contains water, the heat transfer in the hot pressing step 2,73717 is faster and when silane insulation is used, the necessary water for crosslinking is obtained. After the wood fibers have been mixed with the above-mentioned mixer and a small amount of soy solution and polyethylene powder have been added, the mixture is ready to be pressed, in a normal 1 press to a plate at a temperature of 160-180 ° C, time 1mm / ml.

Example 1 100 kg of wood fibers (chips) 5 to 10 kg of 10% soy solution 6 to 10 kg of polyethylene powder mixed with 0.5 to 1.0% of peroxide or silane. Polyethylene melt index 0.01 to 6.0. The wood fibers are rotated in a Papenmeier type mixer, 5-10 sec. after which add 1 soy of soy water, stirring for about 60 sec. Polyethylene powder is then added, mixing time approx. 60 sec. Although the mixing time is only a couple of minutes, the PE powder is already evenly distributed on the surface of the wood fibers and at the same time adheres to them. Follow the compression into plates at a temperature of 160 - 180 C.

The chipboard made in this way has a beautiful surface, mechanically strong, water-resistant, easy to paint.

Claims (3)

1. The method used to detect, in addition to the method used, is to add 11 to the pouch as a spatula with a pressurized spark plug with a sparkling flask at a normal temperature of 160 to 180 ° C. -powder 6 - 10% after release into the tracer, poly-ethylenets with an index value of 0.01 to 6.0, in the case of tracers and polyethylenes with a water content of less than 20%. A process for the production of particle board, in which polyethylene pulp is added to wood chips, after which the chips are thermally pressed into a board, characterized in that 6-10% of the amount of wood chips crosslinked at normal temperature (160-180 ° C) and pressure is used. su1 amis index 0.01 to 6.0, and which is adhered to the surface of the wood fibers with a water-borne Soy 1 solution 11a or the like. 2. The method of claim 1 comprises the use of peroxides or vinyl silicas, which are homogeneous and homogeneous in the form of a mixture, for which a powder of a powder is obtained. Process according to Claim 1, characterized in that peroxide or vinyl is used as the surfactant, which is homogeneously mixed with the polyethylene powder before the powder is added to the wood fibers. Process according to Claim 1 or 2, characterized in that the adhesive and the crosslinking agent-containing polyethylene powder are added to the wood fibers in a high-speed mixer to form a homogeneous mixture which can be pressed into a sheet by hot pressing. 3. A patent according to claims 1 and 2, which comprises a mixture and a mixture of fibers and a mixture of fibers. Härvid fäs en homogenb1andning som varmpressas account en skiva.