"Process for processing fabrics"

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Field of the invention

The subject-matter of the present invention is a process for preparing anti-crease fabrics, in particular highly crease-resistance fabrics. The subject-matter of the present invention are also the fabrics achieved by means of said process, which are optionally subjected to further processings such as anti-stain and/or antimicrobial treatments.

Technical background Cotton is a generally poorly elastic, therefore highly creasable, fabric. This drawback is limited in those fabrics which undergo the anti-crease treatment.

The anti-crease effect is generally evaluated by empirically measuring some parameters such as the so-called "angles". To the purpose of this evaluation, an edge of the fabric under examination is folded and kept compressed for a given period of time under a preset weight, then the reopening angle is evaluated. It is understood that the more the angle approximates 180°, the better the achieved anti-crease effect.

Chemical treatments are known which allow imparting some crease resistance to fabrics, in particular, though not limited to, fabrics originating from cellulose processing, such as cotton. However, when said anti-crease treatments are excessively harsh or inadequately performed, they highly reduce the starting fabric strength.

Resins are commercially available which, by being suitably mixed with acids and other chemical components, can be used in the treatment of fabrics in order to achieve some anti-crease effect. By way of example, the BASF company sells urea-based modified resins and provides guidelines for their use in the manufacturing of fabrics with anti-crease effect, according to various steps comprising: preparing an aqueous solution of said resins with acids and other chemicals; ^l - impregnating the fabric with said aqueous solution; partially drying the fabric, until achieving some residual moisture, about

storing the fabric for a period of about 20-24 hours at 25-30°C; washing and neutralizing with sodium carbonate, and optionally carrying out a further processing with sizings. Following these guidelines, fabrics are achieved, which have improved, but not outstanding, crease resistance features as compared with the starting fabric, for example not sufficient to the crease resistance needs required for items of clothing, such as for example shirts or, again, for household fabrics for which a higher anti- crease effect is desired, such as curtains, tablecloths, etc. Processes similar to those described above are also known which provide drying the fabric to a moisture rate of 9-11% and a longer storage time, but at lower temperatures (40 hours at 20-25°C). Neither these processes provide fabrics with satisfying anti-crease features. It has been now observed that even minor variations in some fundamental parameters of the anti-crease treatment have substantial consequences on the properties of the treated fabric. In particular, it has been observed that the fabric residual moisture before storage, and the storage time itself, are extremely critical parameters, whose correlation highly influences the final anti-crease effect. Summary of the invention The subject-matter of the present invention is to provide an improved process for the anti-crease treatment of fabrics, in particular a process for preparing highly crease resistant fabrics.

Another subject-matter of the present invention is to provide a highly crease resistant fabric, suitable for making items of clothing or household linen, which optionally also has anti-stain and/or antibacterial properties. Detailed description of the invention

Thus, according to one of the aspect thereof, the invention relates to a process for preparing anti-crease fabrics, comprising the steps of:

(a) preparing an aqueous solution of suitable resins with acids and other chemicals;

(b) impregnating the fabric to be treated with said aqueous solution;

(c) partially drying said fabric to a residual moisture of about 7-7.5%;

(d) storing said fabric for a period of about 34-36 hours at room temperature;

(e) washing said fabric with water and, optionally, alkali.

Any cotton or cotton blend fabric can be subjected to the anti-crease treatment of the present invention, although it is however preferable to start from a good quality and good strength fabric, advantageously having a strength higher than 40 kg, for example about 40-45 kg. Fabrics with these features are actually more suitable to undergo the anti-crease treatment which, due to the acids used in combination with the resins, inevitably weakens the structure of said fabric. The resins for use in the step (a) of the process of the invention can be selected from those commercially available. By way of example, one or more resins of the urea-, urea/formaldehyde-, melamine/formaldehyde-based type can be used; dimethylol- dihydroxyethylene-urea is a particularly preferred resin.

Said resins must be mixed with acids, water, and optionally other chemicals in order to prepare the solution which the fabric to be treated has to be impregnated with.

Any mineral or organic acid can be employed for the preparation of said solution, provided that it is suitably strong to lower the solution pH to about 1-2. By way of example, sulfuric acid can be used, optionally in admixture with other acids.

Other components which can be added to the solution of step (a) comprise, for example, wetting, cationic, or amphoteric agents; antifoaming agents, such as surfactants; softening agents, such as polyethylene dispersions; finishing agents, such as polyurethanes; etc.

Examples of solutions for use in step (a) are provided in the experimental section of the present description. During step (b) of the inventive process, the fabric is impregnated with the solution prepared, for example by immersion in suitable tanks; then the excess liquid is removed by squeezing.

The fabric is then evenly dried, during step (c) of the process, using machines suitable to the purpose and known in the art, to a residual moisture of 7-7.5%. The thus-prepared fabric is allowed to rest, according to step (d) of the inventive process, for about 34-36 hours at room temperature, i.e. about 25-3O ⁰ C. During this

storage step, the applied resin becomes cured and permanently fixed to the fabric. As stated above, it has been noted that in order to achieve an excellent anti-crease effect it is necessary to select specific residual moisture rates and to combine them with suitable storage times, said conditions representing the main critical factor which determines the final result.

Therefore, according to an embodiment, the process of the present invention comprises drying the fabric to a residual moisture of about 7-7.5% and storing it at room temperature for about 36 hours. It has been found that it is not possible to generalize, for example by means of intervals, the residual moisture and storage time conditions; however, other specific combinations of the two parameters set forth above can provide as much valid results in terms of the anti-crease effect.

By way of example, a longer storage time must correspond to higher residual moistures. Illustrative examples of some variant embodiments of the process of the invention will be provided in the experimental section of the present description.

After the storage step (d) has been completed, the process of the invention provides a washing and optional acid neutralization step (e). This step can be carried out by simply washing with water, for example by dipping into one or, advantageously, more tanks filled with water and optionally alkali, according to the known methods. The fabric resulting from step (e) is a fabric having excellent anti-crease properties and is per se ready to be used to make items of clothing or linen, for example shirts. However, the thus-treated fabric can be subjected to other specific processings, for example to a finishing treatment in order to provide the fabric with a better final effect, for example to make it softer to the touch, which usually is carried out with sizings and a final "sanforization" treatment, that is a mechanical processing increasing the fabric stability. Both treatments are well known in the art. The inventive process, as described in steps (a) to (e), or according to the alternative embodiments set forth above, provides an anti-crease fabric which has higher angles as compared with those achievable by the prior art processes; for example, it allows achieving angles above 130°, in some cases of about 140-150°.

According to another aspect thereof, the process of the invention also comprises a

further treatment for an anti-crease fabric, for example the fabric resulting from step (e), suitable to impart anti-stain properties to the same fabric. Accordingly, the subject-matter of the invention is also a process for preparing anti- crease and anti-stain fabrics, comprising subjecting an anti-crease fabric, for example a fabric achievable through the process of the steps (a) to (e) set forth above, to an anti-stain treatment. This treatment provides dipping the fabric in a bath containing suitable resins, for example fluorocarbon resins, and optionally softeners, drying the fabric and subjecting the latter to a thermal treatment by means of which the resins are cured. Various types of fluorocarbon resins are commercially available, those of the "repellent" type and those of the "stain release" type. The resins of the first type impart to the treated fabric the feature of not being soiled and not being wetted, while the second ones facilitate soil removal in the washing step. For the anti-stain treatment according to the invention, combinations of various resins, or resins of a single type can be used, according to the result desired to be achieved.

The curing of resins having anti-stain effect is carried out by high temperature heating for some minutes, in average one minute, at a temperature for example of about 160°C, or even higher. Examples of anti-stain treatments combined with the anti-crease treatment will be described in the experimental section of the present description.

According to another aspect thereof, the process of the invention also comprises a further treatment of an anti-crease fabric, for example the fabric resulting from step (e), suitable to impart antimicrobial properties to said fabric. By "antimicrobial properties" is meant, according to the present specification, antifungal and/or antibacterial and/or bacteriostatic properties.

Accordingly, the subject-matter of the invention is also a process for the preparation of anti-crease and antimicrobial fabrics that comprises subjecting an anti-crease fabric, for example a fabric achievable through the process of the steps (a) to (e) described above, to a processing with antimicrobial agents, such as suitable antifungal, antibacterial and/or bacteriostatic agents which preserve the fabric against microbial contamination and/or inhibit the proliferation of the microbial population.

This treatment allows obtaining a durable "fresh" effect on the fabric.

The antimicrobial agents suitable for the treatment described above are known in the art and are commercially available.

The fabrics having anti-crease/anti-stain and anti-crease/antimicrobial properties are further subj ects-matter of the present invention.

The subject-matter of the present invention is also a fabric which concurrently has all the three properties described above, i.e. an anti-crease fabric which at the same time is also anti-stain and antimicrobial.

The two processings suitable to impart anti-stain and antimicrobial features can be carried out either individually or, preferably, in a one-step processing.

For the preparation of the fabric provided with the three properties, the selection of the chemical agents to be used is particularly critical. hi fact, since the anti-stain treatment comprises a high temperature processing step, exceeding 150 ⁰ C, sometimes exceeding 160°C, it is important that the antimicrobial agents selected are capable to withstand high temperatures without undergo degradations or alterations.

Antimicrobial agents intended for this particular treatment on fabrics, which remain unaffected at very high temperatures, even as high as 180 ⁰ C, are commercially available. Examples of the abovementioned treatments and the suitable agents employed will be provided in the experimental section of the present description.

According to a preferred aspect of the present invention, the anti-stain and/or antimicrobial treatments are carried out on anti-crease fabrics which have angles above 130°, even above 140°, for example of about 150°. The anti-crease and/or anti-stain and/or antimicrobial fabrics obtained by the process of the present invention can be used for making items of clothing, such as, for example, shirts, trousers, etc., as well as household linen items.

The anti-crease and anti-crease and/or anti-stain and/or antimicrobial fabrics, which are obtained by the process described above are a further subject-matter of the invention.

The items of clothing and the household linen items obtained from the anti-crease

and anti-crease and/or anti-stain and/or antimicrobial fabrics of the invention are a further subject-matter of the invention.

In particular, shirts obtained from the anti-crease and anti-crease and/or anti-stain and/or antimicrobial fabrics of the invention are a preferred item of clothing of the invention.

The following experimental section better illustrates the invention, without in any way wishing to be limitative thereof. EXPERIMENTAL SECTION EXAMPLE 1 Preparation of an anti-crease cotton fabric

An aqueous solution is prepared by mixing dimethylol-dihydroxyethylene-urea (200 mL/L), cone, sulfuric acid (22 g/L), non-ionic surfactants (1 mL/L), wetting agents (1 mL/L), polyurethane (40 mL/L), and polyethylene as a non-ionic dispersion (20 mL/L). A cotton fabric of about 40 kg strength is immersed in the thus-obtained solution, it is left immersed, squeezed and dried in a field dryer, at temperatures ranging between 70 and 100°C to a residual moisture of about 7%. The fabric is left stored for about 36 hours at a temperature of about 25-30 ⁰ C, then it is repeatedly washed with water. A sizing step is performed, followed by sanforization. An anti- crease fabric is thus obtained having angles of about 135°. EXAMPLE 2

Preparation of an anti-crease cotton fabric

An aqueous solution is prepared by mixing dimethylol-dihydroxyethylene-urea (220 mL/L), cone, sulfuric acid (25 g/L), non-ionic surfactants (3 mL/L), wetting agents (3 mL/L), and polyurethane (25 mL/L). A cotton fabric of about 45 kg strength is immersed in the thus obtained solution, it is left immersed, squeezed and dried in a field dryer, at temperatures ranging between 70 and 100 ⁰ C to a residual moisture of about 10%. The fabric is left stored for about 42 hours at a temperature of about 25- 30°C, then washings with water are carried out alternately to a sodium carbonate aqueous solution. A sizing step is performed, followed by sanforization. An anti- crease fabric is thus obtained having angles of about 140°. EXAMPLE 3

Preparation of an anti-crease and anti-stain cotton fabric

The preparation of the anti-crease fabric is carried out as in the Example 1 or 2.

Before sizing, the fabric is immersed in an anti-stain agent mixture-based bath

(selected among those commercialized under the trade mark Oleophobol®, prepared according to the manufacturer's instructions); the fabric is dried and polymerized for

1 minute at 160 ⁰ C. Then the sizing step and sanforization are carried out, thereby achieving the fabric of the title.

EXAMPLE 4

Preparation of an anti-crease, and antimicrobial cotton fabric The preparation of the anti-crease fabric is carried out as in the Example 1 or 2.

Before sizing step, fabric is immersed in a bath containing an antimicrobial agent of the Sanoitized® type, prepared according to the manufacturer's instructions. Then the sizing step and sanforization are carried out, thereby obtaining the fabric of the title. EXAMPLE 5

Preparation of an anti-crease, anti-stain, and antimicrobial cotton fabric

The preparation of the anti-crease fabric is carried out as in the Example 1 or 2.

Before sizing step, fabric is immersed in a bath comprising 100 mL/L of a mixture of anti-stain agents of the Oleophobol® type, and 10 mL/L of an antimicrobial agent Sanitized® T99.19. Fabric is dried and polymerized for 1 minute at 16O ⁰ C. Then the sizing step and sanforization are carried out, thereby obtaining the fabric of the title.