胶原肠衣是用家畜的皮、腱等为原料制成肠衣。1925年前，国内外都使用天然肠衣加工香肠。天然肠衣是由羊或猪的小肠加工制成的，前者称为羊肠衣，后者称为猪肠衣。这种肠衣具有透气性，不但可以食用，而且能蒸煮，在受热时可与肉类保持收缩一致。然而，天然肠衣的产量受到许多因素的限制，随着肠制品市场需求的扩大，对肠衣的需求量相应地增加，逐渐地出现了肠衣供不应求的矛盾。
Collagen casings are made of skin and tendon of livestock. Before 1925, sausage was processed with natural casings at home and abroad. The natural casings are made from the small intestine of sheep or pigs. The former is called sheep casings, and the latter is called Pig casings. This kind of casing has air permeability, can not only be eaten, but also be boiled, and can keep the same shrinkage with meat when heated. However, the output of natural casings is limited by many factors. With the expansion of the market demand for intestinal products, the demand for casings increases correspondingly, and the contradiction between the supply and demand of casings gradually appears.
同时随着肠制品品种的发展，天然肠衣也暴露出一些缺点，如：完全靠手工操作，劳动力成本高，造成严重的环境污染，并且天然肠衣粗细不规范，不适应机械化生产肠制品，产品质量不易控制。因此，1925年之后出现了人造肠衣。
At the same time, with the development of intestinal products, the natural casings also exposed some shortcomings, such as: completely manual operation, high labor cost, resulting in serious environmental pollution, and the thickness of the natural casings is not standardized, not suitable for mechanized production of intestinal products, product quality is not easy to control. As a result, artificial casings emerged after 1925.