1. Introduction

If synthetic fiber, such as polyester, has more hydrophilic properties, especially water/perspiration absorbency with wash-fast resistance, its use will further broaden.

Meanwhile, cases of cellulosic fiber, which originally possesses great water absorption, turning water-repellent have become frequent recently, resulting from the use of complex finishing composites (e.g. fixing agents, resins, softening agents etc) inhibiting the hydrophilic properties of fiber.

Superior hydrophilic properties (water/perspiration absorbency) will allow varieties of fiber materials, knits, wovens and industrial materials a broader scope of use. Gingham shirting, bedding, knits, toweling, sportswear, casual wear, upholstery, sheeting and table linens are some examples.

Here, the use of a 'durable, water-absorbent & quick-dry SR finishing agent', i.e. a fiber finishing auxiliary capable of a) inhibiting degradation of hydrophilic properties due to repeated home laundering, b) repelling oil and c) soil release (SR) during laundering, will result in the creation of products of high practicality with a broader scope of use.

While the traditional rendering of oil/water-repellent 'SR', for which fluorocarbon polymer is mainly used, stood for the effect of inhibiting oil adhesion, the practical meaning is rather soil-repellent, soil-proofing, soil-guard or soil-resistance.

Originally, the idea of SR finishing was to impart some hydrophilic properties to highly-hydrophobic polyester in order to prevent soil adhesion, especially oil stains, and to produce a fiber surface with oil-release properties.

When hydrophobicity is high, the charging tendency becomes strong, soil adhesion more likely and, ultimately, a stain-darkened material will result. Oil stains also adhere heavily, which makes their removal and washing off difficult.

Taking the above points into consideration, the surface treatment with sufficient hydrophilic properties will bring out the following advantages:

- Water/perspiration absorbency
- Easy oil removal, improved SR and OR (oil-release) properties
- Improved anti-static properties

The use of polymers and chemical compounds other than fluorine-based polymer can also be considered for water absorbent SR. In addition, since the kind of oil staining and the oil concentration often vary, oil-releasing results will differ.

Thus, the application of many different types of hydrophilic stain-resistant agent should be taken into consideration.

This article will deal with two unique products, developed by Kotani Chemical Industry with a view to the multiple purposes mentioned above.

Queenstat NW-E
Water-absorbent, quick-dry, wash-fast anti-staining SR (OR) and softener for polyester

Queenset PSO-5500
Durable water-absorbent anti-static SR, hydrophilic improver for all kinds of fiber, including cotton and polyester

The features of the two products are compared in Table 1.

Textile-finishing polymers are mainly concerned with the development of such products, however, it is also important to know from what chemical substances we need to select an oil-repellent component and an oil-releasing component. The use of a hydrophilic type as the main chain and the selection of copolymerizing, bond-reacting groups from hydrophilic groups will be called into account, as well as the addition of a water-absorbent and a cross-linking groups. A functional group (polymer) formed in this manner needs to be predetermined to act as a stronger cross-link with or a strengthener of adhesion to the fiber materials.

Based on the standpoint above, a short account of some proposals is given in the next chapter.