**Conflict of interest**

There is no conflict of interest in this field.

*Applications of Tannin Resin Adhesives in the Wood Industry DOI: http://dx.doi.org/10.5772/intechopen.86424*

*Tannins - Structural Properties, Biological Properties and Current Knowledge*

and water resistance [63].

manufacturing field is necessary.

& Young Academic and Technical Leaders.

There is no conflict of interest in this field.

**Acknowledgements**

**Conflict of interest**

**6. Conclusions**

weather resistance. Acacia tree tannin has been widely used to prepare lowtemperature curing resin adhesives for finger joint and laminated veneer lumbers [60]. Acacia tannin resin adhesive has a low curing temperature and excellent bonding performance. Additionally, the cost of acacia tannin is lower than that of phenol resorcinol formaldehyde resin. The performance and cost of tanninresorcinol-formaldehyde resin adhesives must be balanced. The tannin content of such adhesives could reach up to 95% after optimization. The polymerization of resorcinol units is replaced by that of a large number of flavonoid tannin natural phenol units. Resin adhesives with high tannin contents can be cured at room temperature, can exhibit good performances, and can be used to produce veneer and finger joint lumbers and glulam [61, 62]. Other nonvolatile or nontoxic aldehydes, such as glyoxal and glutaraldehyde, are also used to synthesize coldset tannin resin adhesives to effectively reduce the problem of formaldehyde release. Although only a small amount of paraformaldehyde is used to cure tannin resin adhesives, the prepared wooden products demonstrate good mechanical strength

Tannin has significant application prospects as a promising natural phenolic polymer. However, this raw material continues to exhibit limitations, such as reactivity, high viscosity, short pot life, and poor weather resistance, among others. Future works must address these problems. Research on tannin resin adhesives should focus not only on wood panels but also on other advanced wooden composites. In addition, the industrialization of tannin resin adhesives in the field of wood

This work is supported by the following grants and programs: 1. National Natural Science Foundation of China (NSFC 31760187); 2. Yunnan Provincial Applied and Basic Research Grants (2017FB060); 3. "Ten-thousand Program" youth talent support program; and 4. Yunnan Provincial Reserve Talents for Middle

**110**
