20、纺织英语---包芯纱

Lesson Twenty：Core – Spun Yarns

Core-spun yarns have a central core with a second layer or sheath of fibers wrapped around

it . Both core and wrapping may be of the same fiber type, or two different fiber types(or more)

may be used. Further, one part may be of filament fibers while the other is of staple fibers; or both

parts may be of either filament or staple – length fibers. The outer sheath may completely cover

the core. When the outer sheath does not hide the center completely, the two components create

interesting appearance effects.

One of the most common types of core – spun yarns is that involving a core of a stretch

filament such as spandex with a covering of staple fibers. It may be also used for a variety of other

fiber types and end uses.

Stretch core – spun yarns can be made using the corespun system. These can be made

economically and exhibit uniformity, good aesthetic appearance, excellent strength, good dyeing

and heat – setting performance.

A relatively new process for making a special type of yarn is called coverspun. It can use any

type of staple fibers, but it is especially desirable for wool, and it uses any type of filament fibers.

Coverspun is described as a bicomponent yarn made of a center or core of staple fibers that are

wrapped with filament fibers that serve as the binder. The process uses a conventional roving as

the supply source for the staple fiber core.

A modification of the process involves three components, a center core of filament fibers

encircled by staple fibers then wrapped by filament fibers.

An important factor of this process is that the staple fibers are not twisted, but rather are

bundled together. This means yarns can be made rapidly. Coverspun yarns have the following

properties:

They are generally stronger than ring – spun yarns. This is due to the filament wrapping and

to a high interfiber friction. They are more even than ring – spun yarns. They have an elongation

equal to ring – spun yarns. They can be used equally well in knitted or woven fabrics.

Fabrics made of these yarns do not look as filaments have been used. Covering power of the

yarns is good. Pilling of yarns in fabrics is reduced. Fabrics are soft and supple and can be light in

weight and thin with little bulk. Yarns have an attractive appearance.

第20课：包芯纱

包芯纱有一纱芯，表面包覆有由纤维构成的表层或皮层。纱芯和表层可以使用相同的纤维，也可以采用两种或两种以上不同的纤维。而且芯部和表层一个可以使用长丝，另一个可以使用短纤维。二者也可以都是长丝或短纤维。表层可以完全包覆芯部，在表层不能完全将芯部纤维包覆时，芯部和表层会呈现一种新奇的外观效果。

最常用的包芯纱之一是芯部采用弹力丝（例如氨纶），表层使用短纤维。包芯纱可以使用多种纤维，并有着多种用途。

利用包芯纱纺纱系统可以生产弹性包芯纱，加工成本较低；纱线条干均匀，外观好，强度高，染性能和热定型性能均较佳。

一种相对比较新的纺纱方法称为包缠纺纱。这种纺纱方法可以使用各种短纤维，最理想的短纤维是毛纤维；此外也可以使用各种长丝纱。包缠纺纱线可以描述为：由短纤维构成的纱芯被长丝包缠的一种双组分纱线，长纤维起捆扎作用。纺纱过程中将常规短纤维粗纱作为芯部原料。

包缠纺纱的一种改进型包括三种组分，芯部采用长丝，长丝外由短纤维包缠，最外面的一层由长丝包缠而成。

包缠纺纱的一个重要特点是，在纱体中短纤维没有加捻，而是被捆扎在一起。这就意味着纺纱速度可以很高。包缠纱具有下述的特点：

一般比环锭纱强度要高，其原因是长丝的包缠作用和纤维间存在较大的摩擦；条干比环锭纱要均匀；伸长率与环锭纱相同；在针织物、机织物的生产中，包缠纱的使用效果都很好；利用这种纱生产的织物，在外观上看不到长丝的存在；纱的覆盖系数较高；织物起球现象减少，比较柔软，蓬松度低且比较轻薄。包缠纱具有赏心悦目的外观。