PROCESS FOR THE PREPARATION OF HEATABLE FABRICS AND FABRICS OBTAINED THEREBY

Abstract

 The present invention is directed to a process for preparing a fabric roll comprising lines of conductive polymer, in which the conductive polymer comprises a base polymer selected from polyurethane, polyester, polyamide and polytetrahydrofuran and a conductive material selected from graphite, graphene, carbon nanotubes, the process comprising the following steps: preparing a conductive polymer composition comprising a polymer, a conductive material and a solvent; depositing conductive polymer lines on a release support by passing the conductive polymer through a grooved blade; drying the product of step b) in an oven; coupling the release support to a fabric; removing the backing from the fabric.
The invention is also directed to a roll of fabric comprising lines of conductive polymer, wherein the conductive polymer comprises a base polymer selected from polyurethane, polyester, polyamide and polytetrahydrofuran and a conductive material selected from graphite, graphene, carbon nanotubes, wherein the lines have a width comprised between 1 mm and 10 mm, and a thickness comprised between 0.1 mm and 2.0 mm.

Description

Field of invention

[0001] The present invention is directed to fabrics that can be heated by polymeric conductive lines coupled to a fabric, to the production of such conductive lines and to the process of making heated fabrics for the clothing sector or for industrial sectors.

Background of the invention

[0002] In the last 20 years or so we have seen the development of clothing suitable for extreme weather conditions, which guarantees the well-being of the wearer not only thanks to good thermal insulation, but also thanks to the presence of a small generator and conductive paths inside the article, which conductive paths ensure the heating of the inside of the article thanks to the dissipation phenomena. These lines were initially made through the use of electrical cables placed inside the garment and connected with a small power generator, for example a battery. However, the use of electrical cables makes the article rigid.

[0003] There are also fabrics with polymeric conductive films that have the function of dissipating the electrostatic charge and promoting thermal comfort. These films, however, are unsuitable to conduct electricity in a controlled way and therefore unsuitable to heat a fabric.

[0004] US 2021/392963 discloses a heatable garment comprising a heatable panel placed inside the garment, which panel includes graphene particles dispersed in a polymer matrix. However, the system is limited to a heating element located in a defined position, and does not offer the possibility of homogeneous heating of the garment. The panels are also made of PVC material that is not suitable for use in clothing due to the problems related to the toxicity of chemicals used to produce it or that are released with use.

[0005] There is therefore a need for a fabric heating system, which allows a homogeneous heating of the product without losing the flexibility characteristics of the product not provided with a heating system.

Brief summary of the invention

[0006] The present invention is directed to a process for preparing a fabric roll comprising lines of conductive polymer, in which the conductive polymer comprises a base polymer selected from polyurethane, polyester, polyamide and polytetrahydrofuran and a conductive material selected from graphite, graphene, carbon nanotubes, the process comprising the following steps: preparing a conductive polymer composition comprising a polymer, a conductive material and a solvent; depositing conductive polymer lines on a release support by passing the conductive polymer through a grooved blade; drying the product of step b) in an oven; coupling the release support to a fabric; removing the backing from the fabric.

[0007] The invention is also directed to a roll of fabric comprising lines of conductive polymer, wherein the conductive polymer comprises a base polymer selected from polyurethane, polyester, polyamide and polytetrahydrofuran and a conductive material selected from graphite, graphene, carbon nanotubes, wherein the lines have a width comprised between 1 mm and 10 mm, and a thickness comprised between 0.1 mm and 2.0 mm.

Brief description of the figures

[0008] 

Figure 1 shows a scheme for the production of a release support on which conductive lines are deposited.

Figure 2 shows a top view of a release support section after depositing the conductive lines.

Figure 3 shows the rifled blade used for depositing the conductive lines on the release support.

Figure 4 shows an example of groove size in the rifled blade.

Detailed description of the invention

[0009] Figure 1 shows the process of preparing the release support on which the conductive lines have been deposited. A release support roll mounted on cylinder 101 is unwinded, held in tension thanks to cylinders 102 and comes into contact with rifled blade 104 that distributes lines of conductive material contained in tray 103 on the support. Immediately after the deposition of the conductive material, the support enters furnace 105 for drying the solvent present in the deposition material of the conductive lines, and at the exit of the furnace, the support is wound to form a roll on cylinder 106. The release support can be made of paper, cardboard, PET or other material that has one or two sides with release coating.

[0010] Figure 2 shows a top view of a release support section, where you can see the conductive lines regularly arranged along the surface of the support.

[0011] Figure 3 shows a rifled blade used in the invention. The blade distributes the conductive material on the release support and, thanks to the movement of the support, forms lines of conductive material on the support.

[0012] Figure 4 shows an example of groove sizes in the rifled blade, where the width of the groove is 3 mm, with a distance between one groove and the other of 2 mm and a groove height of 0.7 mm. However, other line sizes and distance between lines are possible. Preferably, the width of each line is between 1 mm and 10 mm, preferably between 2 mm and 3 mm, while the distance between adjacent lines is between 1 mm and 10 mm, preferably between 1.5 mm and 2.5 mm, even more preferably the distance is between 2 mm and 3 mm. The thickness of the line is also variable and preferably is between 0.4 mm and 0.8 mm.

[0013] The conductive polymer is composed of a resin based on a polymer chosen from polyurethane, polyester, polyamide and polytetrahydrofuran in organic solvent or aqueous additive of a conductive component that can be based on graphite, graphene, carbon nanotubes, other carbon-based materials, metals, for example copper, aluminium, gold, silver, iron or alloys such as steel.

[0014] The use of metals gives good conductivity properties but only if the concentrations are very high ( >15%), this causes the polyurethane to stiffen, and the line becomes very hard.

[0015] The use of graphite works better than metals and is cheaper, but even here very high percentages of graphite are needed to have a good conductivity.

[0016] The preferred materials are carbon black and graphene with the latter as the most preferred. In fact, graphene allows to have a very low starting resistivity and a low specific gravity. You can then turn on the configurations of graphene to get what works best in relation to the price. Various tests have been made of the dispersion of graphene, also in function of the serrations of the blade, and it has been tried to have a polymer that was the least concentrated possible in order not to alter the characteristics of elasticity and flexibility, but also sufficiently concentrated to ensure the passage of electricity. It has been seen that the percolation limit is around 10% so in the final composition there will be 10 parts of graphene per 100 parts of polymer. As graphene increases it improves the resistivity (conductivity) of the line but decreases the mechanical resistance. We have estimated that the best concentration is in the range from 8% to 15% (parts of graphene per 100 parts of polymer).

[0017] The process for the preparation of the fabric with the conductive lines begins with the preparation of the conductive polymer, for example, polyurethane additivated with graphene. An empty container is taken, polyurethane dissolved in an organic or aqueous solvent is added and then, under mixing, the various additives useful for the deposition of polyurethane (antifoam, disaligning, cross-linking, etc.) and graphene are added. The addition of graphene must be done with calm and constancy, preferably it should then be mixed for at least 30 minutes in order to properly disperse the suspension. Everything is then filtered to eliminate possible impurities.

[0018] The conductive polymer is then used to form the conductive lines through a grooved blade and a release support. In particular, the resin is placed inside a "tray" where one side is composed of the striped blade (a wall) and one side is composed of the release support (the bottom). The latter is generally a paper coil with a silicone side, this silicone allows easy detachment of the products that are deposited on it. By operating the production plant, the release support flows carrying the conductive polymer that is forced to pass through the rifled blade that in turn is in contact with the paper.

[0019] The polymer is then forced to pass only through the holes of the rifled blade and what you get are polyurethane wires slightly attached to the release support. Everything then flows through a drying oven where the solvent is extracted from the polymer and what remains is only the polymer with the conductive material.

[0020] The release media and lines are rolled together to protect the lines and keep them in place. The paper also allows not to tension the lines and thus preserve their elasticity and mechanical properties in general.

[0021] After making a roll of release paper with lines on top, you can proceed with the coupling to a fabric. Coupling can be done in several ways: dots, full field, heat-adhesive film, heat-adhesive spray, web, flame or other similar methods. But it is preferred to use dots as it preserves perspiration and elasticity of the finished article. In particular, stitching consists of a system that is able to join two layers (tissues, membranes, rubber or other materials in general) through glue arranged in dots. It is then proceeded by putting the glue on a roll of fabric, adding the release paper with the lines and pressing everything through a calender so that the glue penetrates into the fabric and make a good adhesion with the lines.

[0022] After a few days, the glue will be crosslinked and then will be able to hold the two materials together and withstand washing. Since there is now a good hook between the fabric and the lines, it is easy to remove the release backing which instead was only slightly sticky. What you get is a two-layer article with a fabric on one side and the conductive lines on the other.

[0023] Once you have obtained the roll of fabric with the lines you can proceed to cut it in order to obtain the shapes that will then serve to create the finished article, or generic patches that can be inserted where desired. The lines do not compromise the cut of the fabric which then can be done in the classic ways. After obtaining the desired shape, the circuit is completed.

[0024] What we need to do is to connect the lines in order to create a circuit with resistors that can be heated once the electric current has been applied.

[0025] Connections can be made in different ways: conductive tapes, metal wires, plates, smears, etc.. The choice of mode depends on the type of item you want, cost and performance.

[0026] The definition of the size of the lines in the sense of width, thickness and spacing, and the content of conductive material in the line will define the electrical resistance of each line and thus the amount of current and heat generated by each line. Then, depending on the intended use, or the type of customer, it will be possible, by varying the characteristics of the lines, to produce an article with more or less high heating. It will also be possible, inside the same building, to have areas with more heating and areas where heating is more moderate through careful management of electrical connections.

[0027] Once a cut of fabric of the right size is obtained and connection is made, it is possible to proceed to the realization of the finished article. There are two possible uses of the fabric with the lines, either the fabric is for outside and then the lines are in contact with the body, or that the fabric is for inside and then the stripes are facing outwards. In the first case it is necessary to add a light fabric lining type to not have the lines in direct contact with the body. In the second case, however, it is necessary to add a heavier fabric suitable for stresses with the outside world. In both cases what is obtained is that the lines are "encapsulated" between two tissues, and this allows for less mechanical stress and therefore a longer duration. It is possible that in this stratification technical layers are also added to give the finished garment a waterproof or water repellent performance. During packaging, the battery must also be connected to the circuit.

[0028] The heating of the article takes place through a battery, usually lithium with a voltage lower than 11 V, which by passing the current through the conductive lines heats the fabric through the Joule effect. Depending on the characteristics of the battery and the realization of the electrical circuit, different heating performances will occur. It is then possible to combine the "active" heating strategies for "passive" insulation and then through the addition of insulating layers reduce heat loss and then the use of electricity.

[0029] The invention allows a particular versatility of the processes that allows to vary the heating performance of the finished article through the adjustment of the following parameters: conductive material concentration, coating line design, choice of polymer matrix, choice of type of bonding, choice of support fabric.

[0030] Heating for industrial environments can always be done by batteries with higher voltage/amperage or even directly through other current generators such as, for example, the normal power line of home or factory.

Claims

1. A process for preparing a fabric roll comprising lines of conductive polymer, in which the conductive polymer comprises a base polymer selected from polyurethane, polyester, polyamide and polytetrahydrofuran and a conductive material selected from graphite, graphene, carbon nanotubes, the process comprising the following steps:

a. preparing a conductive polymer composition comprising a polymer, a conductive material and a solvent;

b. depositing conductive polymer lines on a release support by passing the conductive polymer through a grooved blade;

c. drying the product of step b) in an oven;

d. coupling the release support to a fabric;

e. removing the backing from the fabric.

2. The process according to claim 1, wherein the lines in step b) have a width comprised between 1 mm and 10 mm, and a thickness comprised between 0.1 mm and 2.0 mm.

3. The process according to claim 1 or 2, wherein the fabric is made from natural or synthetic fibers or mixtures thereof.

4. The process according to any of claims 1-3, wherein the conductive polymer is polyurethane, and the conductive material is graphene.

5. The process according to any of claims 1-4, wherein the distance between adjacent lines is comprised between 1 mm and 10 mm.

6. The process according to any of claims 4-5, wherein concentration of graphene in the conductive polymer is comprised between 8 parts to 15 parts by weight based on 100 parts by weight of polymer.

7. A roll of fabric comprising lines of conductive polymer, wherein the conductive polymer comprises a base polymer selected from polyurethane, polyester, polyamide and polytetrahydrofuran and a conductive material selected from graphite, graphene, carbon nanotubes, wherein the lines have a width comprised between 1 mm and 10 mm, and a thickness comprised between 0.1 mm and 2.0 mm.

8. The roll according to claim 7, in which the fabric is made from natural or synthetic fibers or their mixtures.

9. The roll according to any of claim 7 or 8, wherein the conductive polymer is polyurethane, and the conductive material is graphene.

10. The roll according to any of claims 7-9, wherein the distance between adjacent lines is between 1 mm and 10 mm.

11. The roll according to any of claims 9-10, wherein concentration of graphene in the conductive polymer is comprised between 8 parts to 15 parts by weight based on 100 parts of polymer.

12. A heatable artifact obtainable by using the fabric roll of any of claims 7-11.

Drawing