Resin finishing

As a 1.7 dtex (1.5 den) fiber, it can be spun into yams with a better strength conversion factor than other ceUulosics, aUowing rotor-spun Tencel to outperform ring-spun cotton or modal viscose. Fabrics can be made at high efficiency, and prove to have the anticipated tear and tensUe advantages over other ceUulosics. Direct, reactive, or vat dyes can be used, and easy care properties can be achieved with less resin finish than normal. Tencel could therefore be positioned as a new premium quaUty apparel ceUulosic and not simply as a long-term replacement for viscose. 

Eyrol 51 is a water-soluble Hquid containing about 21% phosphoms. It is made by a multistep process from dimethyl methylphosphonate, phosphoms pentoxide, and ethylene oxide. The end groups are principally primary hydroxyl and the compound can thus be incorporated chemically into aminoplasts, phenoHc resins, and polyurethanes. Eyrol 51, or 58 if diluted with a small amount of isopropanol, is used along with amino resins to produce a flame-retardant resin finish on paper used for automotive air filters, or for backcoating of upholstery fabric to pass the British or California flammabiHty standards. 

The rate of stripping or the stripabiUty on cataly2ed urethane and epoxy resin finishes can be increased by adding formic acid, acetic acid, and phenol. Sodium hydroxide, potassium hydroxide, and trisodium phosphate [10101-89-0] may be added to the formula to increase the stripabiUty on enamel and latex paints. Other activators include oleic acid [112-80-17, trichloroacetic acid [76-85-9], ammonia, triethanolamine [102-71-6], and monoethyl amine. Methylene chloride-type removers are unique in their abiUty to accept cosolvents and activators that allow the solution to be neutral, alkaline, or acidic. This abihty gready expands the number of coatings that can be removed with methylene chloride removers. 

Aftertreatments include resin finishes, which improve fastness properties, and dye-fixing agents of the epichlorhydrin—organic amine type. These agents react with the dye to give condensation products that are not water soluble and hence more difficult to remove. 

The sulfur dyes are widely used in piece dyeing of traditionally woven cotton goods such as drill and corduroy fabrics (see Textiles). The ceUulosic portion of polyester—cotton and polyester—viscose blends is dyed with sulfur dyes. Their fastness matches that of the disperse dyes on the polyester portion, especiaUy when it is taken into account that these fabrics are generaUy given a resin finish. 

Although in the early days of resin finishing there was continued debate over the mechanism by which these agents achieved smooth-dry performance, by the 1950s most textile chemists beHeved that cross-linking was primarily responsible for achieving smooth-dry performance. 

Early Gross-Linking Agents. Eormaldehyde, urea—formaldehyde, and melamine—formaldehyde were among the eadiest agents utilized for resin finishes. Concerns about the safety of formaldehyde, the need for lower formaldehyde release values, and the safety of exposure to melamine have reduced the use of these early cross-linking agents by industry substantially. 

The ease with which acrylic monomers may polymerise with each other and with other monomers has led to a host of compositions, frequently of undisclosed nature, being offered for use as moulding materials, casting resins, coating resins, finishing agents and in other applications. 

It has been shown that xanthan gum is an effective migration inhibitor for the application of water-soluble chemicals, leading to uniform distribution and more reproducible fixation [379]. Although this work was specifically concerned with the application of a soluble flame retardant to polyester, suitability for the application of reactive dyes or resin finishes is also claimed. 

Early soil-release agents, applied particularly to resin-finished cellulosic goods, were water-soluble polymers, many being related to thickeners (section 10.8) such as starch, hydroxypropyl starch, sodium carboxymethylcellulose, methylcellulose, hydroxyethyl-cellulose, alginates, poly(vinyl alcohol) and poly(vinylpyrrolidone). These functioned essentially as temporary barriers and preferential reservoirs for soil, which was thus easily removed along with the finish in subsequent washing, when they then helped to minimise... 

Substituted triazinyl derivatives of DAS are usually chosen for pad-dry-bake application to cotton in conjunction with an easy-care or durable-press finish. In these mildly acidic conditions (pH about 4) the FBA must show appreciable resistance towards the catalyst (usually magnesium chloride) necessary to cure the resin. The less substantive products in the upper half of Table 11.1 are important in this respect, as are compounds of type 11.9 where R = OCH3 or CH3NCH2CH2OH. It is likely that the hydroxyethylamino groups present in many of these compounds participate in condensation reactions with N-methylol groups in the cellulose-reactant resin. The performance of an FBA applied in conjunction with a resin finish can be modified and improved by careful formulation of the pad liquor but this lies beyond the scope of the present chapter. Alternatively, FBA and resin can be applied in two separate steps most DAST-type brighteners would be suitable if applied in this way. 

A more soluble derivative of compound 11.17, the tetrasulphonated analogue 11.18, has been recommended for application to cotton in combination with a resin finish. Unlike DAST-type FBAs under these conditions, compound 11.18 is compatible with resin formulations containing zinc nitrate as latent acid catalyst. The brightness achieved is not high, however. 

If a padding process is used to brighten a polyester/cotton blend, both the disperse and anionic brighteners may be applied from the same pad bath, even when a resin finish is applied simultaneously to the cellulosic component of the blend. Similarly, both types of... 

Calcobond dyes was that the colour fastness to light was adversely affected. The fastness to acid treatment was no better than that of the resin finish, i.e. the dyeings could be stripped by boiling at a pH below 5. 

Before concluding this section, the rather special technique of autoradiography must be mentioned. This makes use of the fact that ionising radiations will blacken a photographic plate. The technique has been used most elegantly by Park (47—49) to study the distribution of a tritium labelled urea-formaldehyde resin finish in textile fibres. 

Stability of the Dye-Fiber Bond. Because of the large variety of reactive dyes, generalizations about colorfastness are difficult. While wetfastness is determined mainly by the anchor system used, most other fastness properties depend on the dye as a whole or the chromophore present. Most reactive dyes are azo or anthra-quinone derivatives whose standard of fastness varies greatly. Phthalocyanine, formazan, and triphenodioxazine derivatives are also very important. In addition, application conditions and finishing processes of the dyed goods can affect fastness properties. Thus, with some resin-finished textiles (dimethylolpropyleneurea finish) a decrease in lightfastness is observed. 

A related methylphosphate/phosphonate oligomer has primary alcohol end groups, and can coreact with amino resins to form a water-resistant flame retardant resin finish on paper or on textile substrates. The application of this oligomer with a coreactant methylolmelamine on cotton upholstery fabric can enable furniture covered with this fabric to pass the Consumer Product Safety Commission s proposed cigarette ignition test. 

Improved chemical efficiency in resin finishing has been reported by several sources (4, 12, 13, 14), while the relation of water content to dye migration tendency during the drying step of continuous dyeing has been recognized (15, 16). For a current review of prior art low add-on methods, see Leah (16a). 

Foam stability Is less critical for resin finishing or hand modification. However, It must not collapse prior to application on the fabric otherwise the composition will act like a conventional finish and result In high wet pick-ups. 

Dimethyldichlorosilane. Because dimethyldichlorosilane has been polymerized to a silicone polymer on cotton fabrics to impart stain and water resistance and can be applied as a vapor, this agent was examined as a possible consolidant. This treatment also improves fabric hand, resistance to chemicals and weathering, resistance to abrasion (by reducing friction), and reduces the tensile strength loss when resin finishes are applied all factors that should make the material a desirable and effective consolidant. The reactions involved are as follows ... 

Petersen, N., Crosslinking chemicals and the chemical principles of the resin finishing of cotton, in... 

Lund G, Formaldehyde odour problems in resin-finished materials , Shirley Institute Bulletin, 1975,48, 17-21. 

Softener and processing aid for synthetic and natural fibres. Used as a spin finish on acrylic fibres and as a softener on both natural and synthetic fibres. It is particularly effective on acrylics but gives a pleasing soft silky handle on nylon. It is recommended as the softener for chlorine/resin finished wool to overcome the harsher handle resulting from such processes, to aid processing and give a lofty hand. 

Afterfixing agent for improving the wet fastness properties of direct and reactive dyes on cellulosic fibres. Can be applied with easy care resin finishes. 

Catalyst for resin finishing of woven and knitted fabrics of cellulosic fibers and blends. CASSURIT Catalyst AM is an acid donor for crosslinking resins giving a high rate of cure to low formaldehyde glyoxal based reactants. CASSURIT Catalyst AM was developed to provide excellent shade and whiteness retention. 

Besides good heat resistance, FIBRAMOLL CN Liquid has a very good compatability with dye fixatives, resins, and optical bleaching agents and is suited for resin finishing. 

FIBRAMOLL NI is an economical nonionic softener and lubricant for application on synthetics, cotton and cotton/synthetic blends. FIBRAMOLL NI is recommended for resin finishing where excellent whites are needed. Treated fabrics are non-yellowing and chlorine resistant. 

The KAURIT types are either free or etherified N-methylol compounds of urea or of melamine. They are used mainly for the resin finishing of regenerated cellulose fibres, alone and in blends with synthetics. The term "self-crosslinking agents" characterizes their mode of reaction. 

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