Compression pretreatment technology for wood drying and impregnation

I. Technical Overview

Compression pretreatment of logs and sawn timber with high moisture content significantly reduces the moisture content of the wood in a short period of time, decreasing the likelihood of blue staining during long-term air drying and shortening the drying cycle. Furthermore, compression drying pretreatment squeezes out moisture while maintaining a liquid state, saving considerable vaporization energy and effectively releasing growth stress within the wood. This opens up moisture channels, playing a positive role in reducing drying defects and accelerating the drying process in subsequent steps.

By pre-treating logs and sawn timber with compression, the pressure difference between the inside and outside of the wood caused by the rapid rebound of the logs or sawn timber after compression and decompression allows various functional modifiers to continuously penetrate into the wood. In addition, compression pre-treatment disrupts the microstructure of the wood, creating additional penetration channels, thereby further increasing the impregnation rate, impregnation volume, and impregnation depth.

II. Technical Features

By utilizing compression pretreatment techniques involving drying and impregnation, the dimensional retention rate of treated wood can reach over 90%, protecting precious wood resources while its mechanical properties are almost unaffected or even slightly increased.

This achievement not only includes the compression pretreatment technology for wood drying and impregnation in industrial production, but also researches and prepares related equipment according to the requirements of the technology. This equipment serves as a carrier for the industrial production of this technology, providing comprehensive support for its industrial-scale promotion. Due to its rational design, the equipment significantly reduces the precision requirements and the number of parts, thus saving costs while ensuring performance.

This technology is applicable not only to sawn timber but also to logs.

III. Market Prospects

This achievement is suitable for transformation and demonstration in the field of wood drying and impregnation modification. It can significantly reduce the moisture content of high-moisture-content wood in a very short time, solving problems such as long drying cycles and susceptibility to blue stain associated with traditional wood drying methods. Subsequent drying of pretreated wood benefits from two main advantages: firstly, the pit membrane does not shift, providing excellent moisture transfer channels, thus accelerating the drying process; secondly, the compression pretreatment effectively releases the growth stress in the wood, reducing drying defects and improving the quality of dried wood. Therefore, it has promising applications in the field of wood drying. The economic benefits of this technology in solving the blue stain problem, shortening the drying cycle, reducing drying energy consumption, and improving drying quality are immeasurable.

Simultaneously, the liquid impregnation volume of wood treated by this system can be increased at least several times. Therefore, it has promising applications in the industrial production of wood modification and processing, such as dimensional stability treatment, wood strengthening treatment, wood fireproofing treatment, and wood corrosion resistance treatment. The resulting economic benefits from improved fire resistance and corrosion resistance of wood products are also substantial.

With increasing awareness of fire safety in wood products and higher requirements for the durability of wood for outdoor use, especially with the increasing national requirements for fire resistance and outdoor corrosion resistance of wood products, wood compression pretreatment is bound to have a promising application prospect.