Cork cork mulberry (foreign known as cork oak), difficult to adapt to high temperature climate, generally growing in the subtropical, temperate climate zone 400- 2000 meters above sea level in the mountains. Around 32 to 35 degrees north latitude, in accordance with the geographical and climatic conditions of the mountains, most of the cork resources can be seen. For example, Portugal, Spain, the southern region of France, as well as the Qinba Mountains, southwest Henan, Algeria and so on.
Portugal ranks first in the export of cork in the world, known as the "Kingdom of Cork". Because of its special Mediterranean climate, Portugal is suitable for the growth of cork raw materials. At the same time, Portugal is one of the earliest countries in the world in the development of cork resources, raw material export and deep processing of products. Algeria leads the world in cork production. [2]
The Qinba mountain area in Shaanxi Province also contains the rich cork resource, make up more than 50 % of the whole country cork resource. Therefore, Shaanxi is known as the "capital of cork" in the industry. Relying on this resource advantage, domestic large cork manufacturers are mainly concentrated here.
Cork consists of a number of flat cells arranged radiatively. The cells often contain resins and tannin compounds, and the cells are filled with air, so softwood is colored, soft, elastic, impervient to water, resistant to chemicals, and a poor conductor of electricity, heat, and sound. It consists of 14-hedral dead cells arranged radially with hexagonal prisms. Typical cells are 30 microns in diameter and 1 to 2 microns in thickness. There are tubes between the cells. The space between two adjacent cells is made up of five layers, two of which are fibrous, followed by two sequestered layers, and in the middle is a wooden layer with more than 50 million cells per cubic centimeter.