GB2073613A - Binder-coated textiles - Google Patents

Abstract

A textile sheet carrying, on at least one face thereof, a discontinuous coating comprising a binder and metal powder, in which the coating comprises individual areas having an average cross-section of from 0.5 to 2 mm and which cover from 5 to 40% of the surface area of the coated fabric.

Description

SPECIFICATION Binder-coated textiles This invention relates to textile sheets which can have good heat retention, and which comprise a non-woven, woven or knitted fabric carrying a discontinuous coating of a binder and metal powder on one face.

German Offenlegungschrift 11 08 174 discloses a process fortreating a woven fabric, in order to improve its insulating capacity without impairing its porosity, textile handle or flexibility. The process comprises applying a coating comprising a binder and fine metal lamellae to one face of the fabric. The metal lamellae may be distributed in the binder or-on its surface, and they are preferably bonded only to the projecting fibres. The coated woven fabric is very suitable as an interlining for articles of clothing. It has therefore been attenl4ted to apply the process to non-woven fabrics but undesirable stiffening and impairment of porosity are qbserved.

The heat retention properties of a textile sheet, and also its resistance to the passage of moisture, increase with increasing thickness of the sheet. The result of ncreased moisture passage-resistance means that, while a thick textile may feel warm, it may also cause undesirable perspiration after a short period of wear. The thickness of the sheet is usually therefore so chosen -that, -at a given tempera- ture, the properties of heat retention and moisture release are balanced. This compromise -makes for difficulty when the temperature, in use, is distinctly different from the "given temperature" described above.The starting point is generally to achieve a feeling of comfort when the average skin temperature does not exceed 320C,jsolated instances of 32 + 4"C being allowed in certain regions. Further, the degree of perspiration allowed must be less than 30% of the surface area of the skin for a feeling of comfort.

British Patent Publication No. 2,046,775A discloses and claims a textile sheet carrying, on at least one face thereof, a cross-linked binder including from 5 to 50% by weight, based on the weight of the binder solids, of a metal powder having an average particle size of from 3 to 90ju. It is disclosed that such a product can be prepared by applying a binder dispersion having a solids content of not more than 50% by weight and containing from 10 to 50% by weight, based on the solids content, of the metal powder, to at least one face of the sheet, and cross-linking the binder.

According to the present invention, a textile sheet carries, on at least one face thereof, a discontinuous coating comprising a binder and metal powder, in which the coating comprises individual areas having an average cross-section of from 0.5 to 2 mm and which cover from 5 to 40% of the surface area of the coated face.

By ensuring that the individual coated areas are mutually separated, it appears that the porosity/breathing and draping properties of the fabric need not be substantially impaired with respect to the uncoated sheet. This desirable effect can be observed whether the sheet is a woven, knitted or non-woven fabric, and irrespective of whether the sheet has been produced from multi-filament yarns or monofilaments.

Certain mono-filament fabrics, for example spun or staple fibre- non-wovens, have, in addition to a very fine filament structure, a very small, uniform thickness. When such a fabric is coated with a binder suspension or dispersion, it is often difficult or impossible to avoid at least part of the suspension or dispersion penetrating into the interstices of the filaments and/or to prevent the formation of bridges between the filaments and the solids, after crosslinking. This causes undesirable stiffening, in particular when the solids are in the form of flakes or lamellae which cover a plurality of filaments/interstices. This disadvantage can be avoided in the products of the present invention.

Interlining fabrics often contain hydrophilic fibres, e.g. cotton or regenerated cellulose fibres. Such fabrics have a low resistance to the transfer of moisture, but this desirable property may be impaired by the application of a hydrophobic binder if this is unsatisfactorily distributed, e.g. in the form of a discontinuous or continuous film. This disadvantage can be avoided in the products of the invention where from 60 to 95% of the surface area of the coated face of the sheet remains uncoated.

In a product of the invention, the individual areas of coating may be of any desired shape, e.g. elon -gated or circular. Their maximum cross-section will generally be from 0.5 to 1.8 mm. Each area should cover only a minimum part of the individual fibres of the sheet, which preferably are from 12 to 60 mm long. It seems that the observance of these criteria can ensure that a coated product of the invention can have a resistance to the passage of moisture which is of only insignificant difference from the uncoated sheet.

Preferably, the individual areas cover from 10 to 20% of the surface area of the coated face of the textile sheet. It is believed that further advantages can be obtained by the individual areas being arranged in a certain manner. For example, they may be arranged in a regular pattern with a standard mutual separation. In this case, a directional stiffening effect can be observed; for example, the coated sheet may have a better draping capacity in a direction parallel to the rows of individual coating areas than in the mutually orthogonal direction.

Alternatively, the individual areas of coating may be distributed irregularly. For example, the mutual separation oftheareas may vary about a mean value in accordance with a normal random distribution. In achieving such a distribution, it is not possible to avoid the separation of adjacent areas being substantially greater than the average interval in certain portions of the sheet, while certain areas may be close together or even touching. Any disadvantages arising from such a distribution can be simply avoided by arranging the individual areas in a pattern in which the mutual separation varies uniformly about a mean value in accordance with a rectangular distribution. This may be achieved by suitable use of a printing arrangement.

Other distribution patterns may also be produced employing a printing arrangement, and indeed the design of a suitable printing stencil may be simpler than for a rectangular distribution. Further, a suitably random distribution of the areas can be achieved by spreading or spraying.

In general, a textile sheet of the invention may be produced by applying a binder dispersion compris ing fine metal particles to at least one face of a textile sheet. Preferably, the dispersion has a maximum solids content of 50% by weight. It is also preferred that it should not comprise more than 10 to 50% by weight, based on the weight of the solids, of a metal powder having an average grain size of between 3 and 90 ,a (DIN 4190).

Application should be as clean and neat as possible. Accordingly, the viscosity of the dispersion should be adjusted with regard to the chosen application technique. The nature ofthe metal powder should be taken into consideration. While it is preferred that aluminium or an aluminium alloy powder should be used, it is also possible to use a powder of a heavier metal such as brass or copper but the viscosity ofthe binder dispersion should then be somewhat higher, in order to avoid sedimentation during or after application of the dispersion. The appropriate criteria will be readily determined by an expert in the field. It is of course desirablethatthe resultant areas of coating should be of sharp definition.

All known dispersible binders, for example acrylic acid ester polymers, butadiene-acrylonitrile polymers, butadiene-styrene polymers, polysiloxanes and formaldehyde condensation products, and mixtures thereof, are basically suitable for use in the invention. In order not to impairthe pore structure ofthe film which is formed, it has proved to be advantageous to employ, when possible, those binders which can be coagulated at low temperatures. Such an effect can be achieved by adding a heat-sensitising agent or by employing a photo-polymerisable binder. Cross-linking of the applied dispersion is advantageously affected immediately after application to the textile, and only then is the carrier liquid removed, suitably in conventional manner, and for example by drawing off by suction andlor drying with hot air.

The products of the invention are very suitable for use as interlinings and as lining fabrics for articles of clothing. They may also be used as outer fabrics for articles of clothing, in which case the coated face will be on the inside of the article. Ifthe distribution of the individual areas of coating is random, the coated sheet will have a flexibility independent of direction, and this is frequently desirable for a lining or outer fabric. If the textile has a preferred folding direction, as described above for regular patterns of coating, this may be particularly suitable for use in interlinings.

A textile sheet of the invention may be sewn or otherwise bonded to another sheet structure. When bonded, working methods analogous to those used in backing with setting interlinings may be used.

If desired, the binder used in the invention may be coloured. This may be of importance in the manufacture of fashion products and is particularly suitable in preparing lining fabrics.

A product of the invention can have the advantage that it does not transmit incident heat within the plane of the sheet structure. Human skin has different temperatures in different zones. The different degrees of radiated heat from these zones is reflected by a sheet of the invention and this allows the maintenance of the existing temperature differences. This can provide satisfactory comfort in wear and is a feature of great importance.

The following Example illustrates the invention.

All parts are by weight.

Example A soft random fibre non-woven consisting of 15 parts of heterofilamentfibres (core polyamide 66, sheath polyamide 6) dtex 3.3/40, semi-matt 35 parts of polyamide 66 fibres dtex 3.3/60, matt 30 parts of polyamide 66 fibres dtex 3.3/51, matt 20 parts of polyestef fibres dtex 3.3/60, matt with a weight of about 40 g/m2, was preconsolidated by heat in a manner knownperse and then printed with a printing paste having a solids content of 30% and consisting of Parts Al powder (average particle size 25 t 100 Polyacrylate dispersion 150 Polybutadiene dispersion 150 Melamine resin 60 Polyvinyl alcohol 30 Diethylene glycol 50 Diammonium phosphate 1.5 Antifoam agent dispersion 30 Water 630.7 1194.2 Printing was effected using a 25 mesh printing film, hole IZI 0.5 mm, thickness 0.22 mm. A 40 glum2 coating was applied and then dried.

The coated non-woven fabric was sewn into the right-hand half of the chest portion of a windproof jacket, below the outer fabric. A non-woven fabric which had been treated with the same binder dispersion minus the metal powder, was sewn into the same jacket in the left-hand half of the chest portion, + in the same way. The lined jacket was then donned by a subject who stayed at rest in a room at a temp- erature of 20"C. After 10 minutes, a photograph of the chest portion was made with an infra-red thermo-camera (Thermograficlmager, Model 800).

It was possible to demonstrate with the aid of this photograph that the average surface temperature of that half of the chest portion which was provided with the interlining fabric according to the invention was 1.5 to 2C degrees above that of the opposite side. Consequently, for the same resistance to the passage of moisture, a substantially improved heat insulating effect was obtained.

In order to exclude any influences of the subject, the test was repeated with the fabrics sewn into the jacket in mirror image fashion. The infra-red photograph revealed the same effect as before.

Claims (11)

1. Atextile sheet carrying, on at least one face thereof, a discontinuous coating comprising a binder and metal powder, in which the coating comprises individual areas having an average cross-section of from 0.5 to 2 mm and which cover from 5 to 40% of the surface area of the coated fabric.

2. A sheet according to claim 1 in which the areas are arranged in a regular pattern, at equal intervals.

3. A sheet according to claim 1 in which the areas are arranged such that the separation of adjacent areas varies randomly about a mean.

4. A sheet according to claim 1 in which the areas are arranged such that the separation of adjacent areas varies, with a rectangular distribution, about a mean.

5. A sheet according to any preceding claim in which th e a reas cover from 10 to 20% of the surface area of the coated face.

6. A sheet according to any preceding claim in which the metal powder has an average grain size of between 3 and 90 cm.

7. A sheet according to any preceding claim in which the material of the coating comprises open or closed pores.

8. A sheet according to claim 1 substantially as described in the Example.

9. A process for producing a sheet according to any preceding claim which comprises applying to the at least one face of the uncoated sheet a binder dispersion having a solids content of not more than 50% by weight and which contains from 10 to 50% by weight, based on the solids content, of the metal powder.

10. A process according to claim 9 in which the binder is coagulated immediately after application and the liquid phase is then removed.

11. A process according to claim 9 substantially as described in the Example.