Laminated wood

Boards or small square timber are laminated and glued together parallel to the direction of the fibers. Laminated lumber made from sawn boards or thick boards is called laminated lumber, and laminated veneer lumber (LVL) is called laminated veneer lumber. Improved wood made by impregnating veneer with phenolic resin and bonding and compressing it at a high pressure of more than 100 kilograms per square centimeter is called hardened laminated lumber or reinforced wood, and has been used in places where high strength, high electrical insulation, and durability are required. Laminated lumber impregnated with synthetic resin to improve water resistance, dimensional stability, and abrasion resistance is also used for special parts such as floors and handles, and for tableware. WPC (wood plastic combination) is often included in this category of laminated lumber. Laminated veneer lumber is generally made by stacking rotary veneers in parallel and gluing them together. It is also called parallel plywood and is used to make flat boards, but it is also used for square timber applications such as framing and crosspieces. The word "laminated" means to overlap or glue, so in a broad sense it can include plywood, lumber core plywood, and also laminated boards or blocks such as flooring. The effect of lamination is to increase uniformity and strength properties in laminated lumber and laminated veneer lumber, and to obtain dimensions and shapes that are difficult to obtain with wood. Also, lamination by impregnation with synthetic resin makes use of the properties of wood and synthetic resin, imparting strength to wood and water resistance and dimensional stability to synthetic resin.

[Arima Takashi]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

板または小角材などを繊維方向に平行にして積層接着したもの。ひき板、厚板の積層材を集成材、単板を積層したものを単板積層材（LVL＝laminated veneer lumber）とよぶ。単板などにフェノール樹脂を含浸させ、1平方センチメートル当り100キログラム以上の高圧力で接着圧縮した改良木材を硬化積層材または強化木(きょうかぼく)とよび、高い強度と高い電気絶縁性、耐久性を要求されるところにかつて使用されたことがある。合成樹脂を含浸させて耐水性、寸度安定性、耐摩耗性を高めた積層材も、床や取っ手のような特殊な箇所あるいは食器などにも用いられる。WPC（wood plastic combination）もこの積層材に含まれることが多い。単板積層材は一般にロータリー単板を平行に重ね合わせ接着したもので、平行合板ともよばれて平板をつくるが、角材的な用途たとえば枠材、桟木(さんぎ)などにも用いられている。積層ということばには重ね合わせ、接着する意味があるので、広義には合板、ランバーコア合板のほかに、フローリングのように板やブロックを重ね合わせたものなども含まれることがある。積層の効果は、集成材や単板積層材では均一性を増し、強度特性を高め、木材では得がたい寸法形状を得られる。また、合成樹脂の含浸による積層は、木材と合成樹脂の特性を生かしており、木材で強度を、合成樹脂で耐水性、寸度安定性を付与している。

［有馬孝］

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