Bleaching and dyeing; fluid treatment and chemical modification – Diffusion transfer dyeing process – transfer sheet and product
Reexamination Certificate
2000-04-25
2002-07-30
Gupta, Yogendra N. (Department: 1751)
Bleaching and dyeing; fluid treatment and chemical modification
Diffusion transfer dyeing process, transfer sheet and product
C428S195100, C428S327000, C427S148000, C427S151000
Reexamination Certificate
active
06425927
ABSTRACT:
BACKGROUND OF THE INVENTION
a) Field of the Invention
The invention is directed to an aqueous composition for finishing fibrous material for a thermal transfer printing process, the use of the composition therefor, and a thermal transfer printing process.
b) Description of the Related Art
It is generally known to dye synthetic fibers, e.g., polyester fibers, with disperse dyes. However, disperse dyes are only poorly soluble in water. For dyeing, the ground disperse dyes are dispersed in water. They penetrate into the synthetic fibers by diffusion and form a “fixed solution” which provides colored fibers with excellent resistance to laundering in water because of the poor solubility.
In a thermal transfer printing process, the disperse dye is applied first to a carrier, e.g., paper with a special coating, by means of a printing paste. By pressing together with the textile material to be imprinted and by heating, the disperse dye on the carrier is sublimated off the carrier and applied to the textile material. The high temperature used in this process promotes diffusion of the dye into the fibers of the textile material. This transfer of dye to the textile material is usually carried out at a temperature between 200 and 250° C. within a few seconds.
It is a prerequisite of thermal transfer printing that the disperse dye can diffuse into the fibers. However, this is not the case with natural fibers such as cotton or wool or with regenerated cellulose fibers. These fibers must first be suitably finished.
For this reason, there have been numerous attempts to provide suitable finishes for fibers which overcome the above-mentioned disadvantage.
For example, the German Patent 41 26 096 discloses a process for printing on substrates by means of transfer printing methods in which a resin-free transparent varnish or lacquer is applied to and dried on the natural fibers to be imprinted, wherein this lacquer can absorb and fix the sublimable dyestuffs in the subsequent thermal transfer printing process. As defined in Rompp Chemie-Lexikon, 1990, page 2424, lacquers are substances in liquid or powder form which are applied in thin coats to objects and which, as a result of chemical reaction and/or physical change, form a solid film which adheres to the objects. However, formation of films results in an unwanted reduction in air permeability and impaired breathing properties as well as in a relatively hard feel of the textile material.
Further, it is known to generate a duroplast in natural fiber materials by treating them with synthetic resins, wherein this duroplast is fixed so as to be wash-resistant and can absorb the disperse dyes. For example, the Swiss Patent 564 637 describes a process for simultaneously generating wash-fast fixed dyeing or printing based on the sublimation transfer method and high-grade finishing on textile fabrics formed entirely or partially of cellulose fibers, in which process the textile material is first treated with an aqueous solution of a crosslinking agent for the cellulose and, after pre-drying, is dyed or imprinted according to the transfer printing method. In so doing, the cellulose fibers are crosslinked during and/or after the transfer printing in the presence of a catalyst by application of heat and the dyes are accordingly fixed in the fibers so as to be wash-fast. While this treatment achieves the goal of dye affinity or power to absorb dye, it leads to an unwanted stiffening and harder feel of the textile material when a sufficient amount of crosslinking agent is applied for the transfer printing.
OBJECT AND SUMMARY OF THE INVENTION
Therefore, it is the primary object of the present invention to provide a composition for finishing fibrous material for a thermal transfer printing process which does not reduce air permeability or breathing of the fibrous material in an unwanted manner after printing and which provides the fibrous material with a pleasant, soft feel.
According to the invention, this is achieved by an aqueous composition for finishing fibrous material for a thermal transfer printing process comprising
a) 0.5 to 2.5 percent by weight of a synthetic resin precondensate,
b) 10 to 30 percent by weight of a thermoplastic plastic with reactive groups,
c) 0.1 to 1.0 percent by weight of an inorganic salt with an acidic reaction,
d) 0.2 to 2.0 percent by weight of a softening agent, and
e) 0.05 to 0.5 percent by weight of an emulsifier,
wherein the indicated amounts are in relation to the composition.
DETAILED DESCRIPTION OF THE INVENTION AND EXAMPLES THEREOF
By the expression “aqueous composition” is meant that it contains, in addition to the aforementioned components a) to e) and possibly other conventional components, water for making up to 100 percent by weight, i.e., the remainder is water. These components can be present in an amount of up to 5 percent by weight in relation to the composition.
The composition according to the invention has, as component a), a synthetic resin precondensate in the above-indicated amount. The treatment of cellulose fibers with synthetic resin precondensates (crosslinkers) is a process which is generally known in the textiles field and is extensively described in technical literature pertaining to textiles; for example, reference is had to H. Tovey, Textile Research Journal 31, pages 185 to 237 (1961), H. Rath. Zeitschrift für die gesamte Textilindustrie 69, pages 542 to 548 and pages 631 to 635 (1967), and the Swiss patent cited above.
The synthetic resin precondensates can be monomeric compounds which can contain two or more reactive groups which can react, on the one hand, with cellulose, especially the OH groups of cellulose, and on the other hand with the reactive groups of other synthetic resin precondensate molecules accompanied by formation of a covalent bond. Accordingly, the molecules of the synthetic resin precondensate can react with each other and be crosslinked with the cellulose. Examples of reactive groups are carbonyl, carboxyl and methylol groups.
Examples of synthetic resin precondensates are acetals, e.g., reaction products of formaldehyde and diethylene glycol, dimethylol monocarbamates, e.g., dimethylol methyl carbamate, dimethylol urea, dihydroxyethylene urea, propylene urea and derivatives thereof, triazones such as dimethylol-5-methoxyethyl-1,3,5-triazinon-2, methylol melamine compounds such as tetramethylol melamine or water-soluble etherified methylol melamine compounds, hexamethylene diethylene urea and glyoxal and derivatives thereof.
The synthetic resin precondensate can also have reactive groups which are different from each other.
The synthetic resin precondensate is preferably a compound containing at least two methylol groups (—CH
2
—OH) which are advantageously bonded to N-atoms, wherein the N-atoms can be different or can be the same N-atom. In this connection, it is advantageous when the N-atom neighbors on a carbonyl group. Examples of such N-methylol compounds are dimethylol ethylene urea and compounds derived therefrom. The H-atom of the OH group of the methylol group can be substituted by an alkyl radical, e.g., a C
1
-C
4
alkyl radical. If desired, the H-atoms of all or only of some of the OH groups of the methylol groups can be replaced by alkyl radicals.
Examples of compounds derived from dimethylol ethylene urea are those having the following formula:
where R′ and R″ are identical or different and stand for H and OH, and R
1
and R
2
are identical or different and stand for H and C
1
-C
4
alkyl. An example of a compound having the above formula which is derived from dimethylolethylene urea is dimethyloldihydroxyethylene urea.
These compounds have the advantage that only a very slight formaldehyde emission was determined when they were applied to the fibrous material and during the subsequent reaction of the synthetic resin precondensate molecules with one another, with the thermoplastic plastic and with cellulose. This is advantageous in view of the toxicologic disadvantages of formaldehyde. Further, the compounds having one of the alkyl radicals m
Haupt-Stephan Renate
Linder Renate
Dr. Th. Boehme KG Chem. Fabrik GmbH & Co.
Gupta Yogendra N.
Hamlin Derrick G.
Reed Smith LLP
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