Study on Ultraviolet Fixing Crosslinking Adhesives

Decorative ribbon fabrics (known as lace fabrics) are woven fabrics made from a variety of fibers such as polyester, viscose, and polyamide. Based on the different types of fibers, the ribbons are pre-treated, dyed with different types of dyes, sized, and further processed. In particular, dyeing and rinsing require a large amount of energy and generate a large amount of waste water. The continuous dyeing of Langers thin cloths also requires adding a large space (about 30 cubic meters). For this reason, people have been studying whether the ribbon fabric can be dyed with ultraviolet curing technology. This technology was previously successfully used in the printing, packaging and furniture industries. This technology has the advantages of low energy input, no waste water, small space, and short curing time (about 2 to 4 seconds).

Fundamental Principles Liquid reactive adhesives can be rapidly cured by high energy UV light (polymerization). The research system contains acrylate components, diluents, and photoinitiators. Dyes (disperse dyes or pigments) are added to this system. Ultraviolet light is used to generate active species (radicals) from photoinitiators.

Active species start free radical polymerization. The use of UV-curable adhesives and dyes for dyeing fabric backings is rarely used in practice. Therefore, an in-depth study of the adhesive formulation is required in advance. After curing, the system was analyzed based on flexibility and yellowness. Apply a liquid binder to the fabric backing with a pad or spray prescription.

In addition to the artificial spray, the belt fabric can also be automatically dyed, cured and rolled up using the test device developed in this study. The device requires only about 1 cubic meter of space. Calendering can be done selectively after curing.

Laboratory results The experiments done on the binder/pigment system and the dyed ribbon fabric in the German laboratory yielded the following results:

It is technically feasible to use a new type of UV curing method to dye polyester and CV non-woven polyamide braided tape fabrics. An adhesive system is suitable for all kinds of fibers.

The wetting ability of the pigment strongly influences the rubbing fastness of the dyed ribbon fabric. In order to evaluate the wetting ability of the pigment, the contact angle was measured. According to the value of the contact angle, wetting can be divided into the following three cases: complete wetting; no wetting or incomplete wetting. After testing, the rubbing fastness of the dyed ribbon-like fabric was consistent with DIN54021. Combining all the results with the contact angles described above, it can be concluded that the best rubbing fastness can be obtained when the pigment is completely wetted by the adhesive aid system.

UV-cured ribbon fabrics have a softer handle than conventionally dyed ribbon fabrics. According to the cantilever test DIN 53362, the flexural strength was tested to quantitatively evaluate the feel of the ribbon fabric. The test gives the flexural strength values ​​of polyester fabrics dyed by different methods. The flexural hardness value (feeling hard) of the fabric dyed by the UV technology was significantly higher than that of the conventional polyester fabric dyed (feel soft). However, the flexural strength values ​​of UV-cured ribbon fabrics can be improved by subsequent calendering so that the ribbon fabrics become more flexible.

In order to find out the reasons for the differences in hand feel before and after calendering, the researchers used a scanning electron microscope to test the cross-linked parts of the tape-like fabrics. The cross-linked parts of the polyester tape-like fabrics dyed by the conventional method and the ultraviolet method showed the following situations: The warp yarns of the dyed ribbon fabric were loose; the weft yarns of the UV-dyed dyed fabric were almost completely coated and fixed. Due to the coating, the flexibility of the filaments is greatly suppressed and the feel is hardened. Due to the force applied during the calender finishing, the coated part cracked, resulting in a better feel.

Problems that exist Different application methods and calendering methods affect the color depth of light indentations. Spraying produces deeper colors. However, calendering can reduce the depth of color. During calendering, the pigment-containing coating is embedded in the textile fiber structure resulting in a reduced depth of color. It is clear that the concentration of the pigment is related to a decrease in the color depth of the surface, which results in light-colored indentations.

The test results show that it is possible to dye fabrics, especially UV-cured curing technology, for dyeing decorative fabrics. The interrelationship between different parameters not involved in this work provides the basis for further research. Taking into account the increasingly harsh environmental constraints and the overall efficiency of the production process, people should pay more attention to the role of UV-fixing technology in fabric finishing.

Reprinted from: International Textile Review