Sealing layer to prevent the leakage of infiltration resins during the impregnation of wood

Abstract

Sealing layer for application to wood treated with polymerizable infiltration resins, characterized in that, after application and drying, it forms a dense, elastic and resin-compatible barrier which prevents the resin from escaping during thermal curing without being impaired in its function or curing by components of the impregnating agent.

Description

State of the art

[0001] To improve the resistance of wood to moisture and environmental influences, wood products are frequently impregnated with polymerizable synthetic resins, particularly acrylate or methacrylate systems, under vacuum. The resin used typically consists of a resin component and a hardener component that cures at elevated temperatures. To control the reaction, the wooden parts are often wrapped in aluminum foil. However, the heat generated by the reaction causes the resin component to expand, leading to resin seepage. This seepage results in defects, material loss, and costly rework. Until now, no effective method for preventing this seepage has been known. Description of the invention

[0002] The invention relates to a novel sealing layer that is applied to wooden surfaces previously treated with a polymerizable infiltration resin. After application and drying, the sealing layer forms a dense, elastic, and temperature-stable protective layer that prevents the resin from seeping out during thermal curing and simultaneously acts as an oxygen barrier.

[0003] Previously used coatings or sealants, for example those based on waxes, varnishes, or synthetic resins, exhibit significant disadvantages. Many of these substances react with the resin component of the impregnating agent or prevent its complete curing. Others are dissolved by the impregnating agent or lose their barrier properties during temperature curing. Surprisingly, it has been found that a sealing layer based on an alcoholic solution of a suitable, resin-compatible polymer—particularly polyvinyl alcohol—avoids these problems. Such layers cure independently, are not affected by the impregnating agent, and reliably prevent resin leaching. Advantages of the invention • Prevents the leakage of infiltration resin during curing • Forms a homogeneous, smooth and transparent surface • Serves as an oxygen barrier and improves curing • Reduces rework and material waste • Easy to apply by brushing, spraying or dipping • Improves the durability and aesthetics of wood products • Does not react with the impregnating agent and remains stable during curing. Example of implementation

[0004] A piece of wood impregnated with acrylate resin is evenly coated with a 5% solution of polyvinyl alcohol in ethanol before thermal curing. After drying, a thin, closed layer forms, which completely prevents resin from seeping out during curing at 90 °C. After curing, a clear, smooth, and durable surface remains on the wood.

Claims

[1] Sealing layer for application to wood treated with polymerizable infiltration resins, characterized by that after application and drying, it forms a dense, elastic and resin-compatible barrier which prevents the resin from leaking out during its thermal curing, without being impaired in its function or curing by components of the impregnating agent. [2] Sealing layer according to claim 1, characterized by that it is a layer of polyvinyl alcohol (PVA) applied from an alcoholic solution, preferably in ethanol or isopropanol. [3] Sealing layer according to any of the preceding claims, characterized by that the polyvinyl alcohol solution contains 1-10 wt% PVA. [4] Sealing layer according to any of the preceding claims, characterized by, that it forms an oxygen barrier and enables uniform polymerization of the infiltration resin up to the surface. [5] Use of the sealing layer according to any one of claims 1-4 for the production of wood-finished products with a fully impregnated and sealed core, in particular gunstocks, knife handles or decorative wooden objects.