JPH02178002A - How to make particleboard or medium density fiberboard - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for manufacturing particle board or medium density fiberboard.

[Prior art] Conventionally, when manufacturing particle board or medium density fiberboard (MDF) (hereinafter referred to as particle board, etc.), a forming mat was conveyed in a rolling machine during the pressing process, and as soon as all stages were full, a hot press was applied. The board was formed under pressure. However, when the adhesive is applied to the chip dried in the dryer, the chip temperature is 5.
If a highly reactive adhesive such as incyanate is applied at a temperature of 0 to 60°C, the adhesive will precure before being hot-press molded, resulting in only a board with low strength and especially poor surface properties. I couldn't get it.

In particular, when manufacturing the above-mentioned particle boards, etc., it takes time for the forming mat to be compressed to the specified board thickness, so the adhesive on the surface layer close to the surface of the mat that comes into contact with the hot press plate is pre-cured. was waking up.

In order to solve this problem, a suitable amount of water that acts as a plasticizer has been sprinkled onto the heating plate, but this has resulted in problems such as adhesives and adhesive-coated chips adhering to the heating plate. occurred, and its practical value was low.

[Object of the Invention] An object of the present invention is to eliminate such drawbacks and to provide a method for producing a hard particle board or the like having excellent surface properties and having no or very few precure layers.

[Disclosure of invention] The present invention will be described in more detail as follows.

The present invention is characterized in that an adhesive containing a superabsorbent polymer compound is applied to and mixed with wood chips or wood fibers, followed by forming and then hot-press molding to form a board of a desired thickness.

The shape and size of the wood chips or wood fibers used here are not particularly limited, but various shapes such as powder, needle, strand, or wafer are used. Regarding the size, the length is 0.5 to 50 mm.
, a width of 0.5 to 50+u+, and a thickness of 0.5 to 1 layer, but it is not limited to these numerical ranges.

The adhesive used in the present invention is, for example, a urea resin adhesive or a urethane resin adhesive to which a polyacrylic superabsorbent polymer compound is added.

Examples include, but are not limited to, urea-melamine cocondensation resin adhesives to which a carboxymethylcellulose (CMC) superabsorbent polymer compound is added.

In addition, in the above various adhesives, the amount of water contained in the super absorbent polymer compound added is 400 times or less, preferably 10 to 300 times the weight of the super absorbent polymer compound; Needless to say, it is arbitrary within the range of normal use.

As explained above, if an adhesive containing a highly water-absorbing polymer compound that absorbs water and swells is applied to and mixed with wood chips or wood fibers, all the water in the adhesive will be removed from the wood chips. or the moisture is scattered on the wood chip or wood fiber surface without being absorbed by the wood fibers, thus preventing the adhesive from pre-curing,
A board with a hard surface can be replaced.

[Example] Next, examples of the present invention will be shown.

Example 1 Fine wood chips for the surface layer (temperature 55°C) and coarse wood chips for the inner layer (temperature 60°C) from the dryer
35% of a highly water-absorbent polymer compound (trade name: Aqualic C5: Nippon Shokubai Chemical Industry Department) made by absorbing 300 times as much water as 100 parts by weight of Yurya-melamine cocondensation resin with a resin solid content of 85%. When applying adhesives with parts by weight added, 12% by weight of the wood chips for the surface layer and 8% by weight of the wood chips for the inner layer. After forming the applied wood chips in the order of surface layer wood chips, inner layer wood chips, and surface layer wood chips, the temperature is 160℃ and the pressure is 25kg.
A desired particle board having a thickness of 15+sm was obtained by hot pressing at f/cm2 for 5 minutes. This particle board did not have a precure layer, had a glossy surface, and had a hard surface.

Example 2 Liquid nitrogen was sprayed onto the fine surface layer wood chip fibers (temperature 55°C) and inner layer wood chip fibers (temperature BO°C) that came out of the dryer to adjust the temperature of the surface layer wood chip fibers. The temperature of the wood chips and fibers for the inner layer was lowered to 35°C to 40°C, and as an adhesive, a super absorbent polymer compound (trade name Nigelfin:
Adhesive to which 30 parts of Daicel Chemical Industry Co., Ltd. (made by absorbing and swelling 30 times more water) was added, 12% based on the weight of the chips and fibers for the surface layer, and 8% based on the weight of the chips and fibers for the inner layer. % respectively applied and mixed, then forming, temperature 130℃, pressure 28kgf/cm
2. A desired medium density fiberboard having a thickness of 12 mm was obtained by hot pressing for 10 minutes. Similar to Example 1, this medium density fiberboard had almost no precure layer and was a medium density fiberboard with excellent glossy surface performance.

Example 3 A highly water-absorbent polymer compound made by absorbing 300 times as much water as 100 parts by weight of a Yurya-melamine cocondensation resin with a resin solid content of 65% on fine surface wood chips (temperature 55°C) that came out of a dryer. (Product name: Aquaric C3: manufactured by Nippon Shokubai Chemical Industry Co., Ltd.) An adhesive containing 35 parts by weight of adhesive was applied at 12% based on the weight of the wood chips, and the resin solid content was 65% for the rough inner layer wood chips (temperature 60°C). A Yurya melamine cocondensation resin of 8% based on the weight of the wood chips was applied.Next, the wood chips coated with these adhesives were formed into wood chips for the surface layer, wood chips for the inner layer, and wood chips for the surface layer in this order. After that, temperature 180℃ pressure 25kgf/c
A desired particle board having a thickness of 15a+i+ was obtained by hot-pressing molding at m2 for 5 minutes. This particle board did not have a precure layer, had a glossy surface, and had a hard surface.

[Effects of the Invention] Since the present invention has the above-described configuration, it has the following effects. That is, a particle board or medium-density fiberboard with no or very few precure layers can be obtained, and a hard particleboard or medium-density fiberboard with excellent surface properties can be obtained.

Claims (1)

[Claims] In a method of manufacturing particle board or medium density fiberboard by applying adhesive to chips or fibers and hot-pressing molding, an adhesive is added to the above adhesive with a super absorbent polymer compound that absorbs water and swells. A method for producing particle board or medium density fiberboard, characterized in that it is used.