Method for producing a breathable film

Abstract

A method for producing a breathable film based on polyvinyl chloride (PVC), including the following steps. Preparing a paste-like compound including a first fraction composed of PVC, a second fraction composed of a foreign material, and a third fraction composed of adjuvants and/or additives that that are mixed together to form the paste-like compound, applying the paste-like compound to a base, and drying and gelling the paste-like compound, which has been applied to the base, through the addition of heat, thus forming the film in which pores extending from the one surface of the film to the other are formed, which give the film breathability.

Claims

1. A method for producing a breathable film based on polyvinyl chloride (PVC), including the steps of: preparing a paste-like compound including a first fraction of PVC, a second fraction of a foreign material including a dispersion based on polyether polyurethanes, polyester polyurethanes, polycarbonate polyurethanes or mixtures thereof and water, and a third fraction of adjuvants and additives mixed together to form the paste-like compound, wherein the paste-like compound is produced from the fractions without addition of an organic solvent other than water; applying the paste-like compound to a base; and drying and gelling the paste-like compound applied to the base, through addition of heat, to form the film in which the foreign material causes pores extending from the one surface of the film to an other surface of the film, wherein the pores have an average pore diameter of 1 μm to 1 mm to provide the film breathability with a gas permeability of 0.1 to 200 l dm.sup.−2 min.sup.−1 and a water vapor permeability of 0.1 to 200 mg cm.sup.−2 h.sup.−1.

2. The method according to claim 1, wherein the first fraction includes an emulsion PVC with a K value of 65 to 80 or suspension PVC or mixtures thereof.

3. The method according to claim 1, wherein the second fraction includes a mixture of water and an emulsifier.

4. The method according to claim 3, wherein the emulsifier includes a polyethylene-, sulfate-, phosphate-, or amine-based soap.

5. The method according to claim 3, wherein the second fraction in relation to 100 wt. % of the first fraction, contains 2 to 50 wt. % water and 0.2 to 10 wt. % of the emulsifier.

6. The method according to claim 1, wherein the paste-like compound contains 2 to 60 wt. % of the second fraction and 98 to 40 wt. % of the first fraction, with a sum of the first fraction and the second fraction equaling 100 wt. %.

7. The method according to claim 1, wherein the adjuvants and the additives include fillers, softeners, cross-linking agents, stabilizers, kickers, silicones, flame retardants, additives and/or pigments.

8. The method according to claim 7, wherein fillers are provided in the form of calcium carbonate, cellulose, calcium sulfate, barium sulfate, silicon dioxide, aluminum dioxide, zinc oxide, and/or zinc bromide.

9. The method according to claim 7, wherein softeners are provided in the form of phtalates, adipates, sebacates, citrates, 1,2-cyclohexane dicarboxylic acid diisononyl ester, dioctyl terephthalate, epoxy softeners, glycol-, oligoglycol-, or polyethylene glycol-based softeners, castor oil-based softeners, polymer softeners, phosphate softeners, cyclic nonaromatic softeners, chlorinated and brominated softeners, sulfate softeners, and/or ionic liquids.

10. The method according to claim 7, wherein cross-linking agents are provided in the form of isocyanates, acridines, carbodiimides, melamines, and/or peroxides.

11. The method according to claim 7, wherein the stabilizers and/or the kickers provided are based on barium, calcium, cadmium, tin, lead, mercury, antimony, arsenic, thiols or mercaptans, phosphites or phosphates, OBS, zinc, magnesium and/or aluminum, phenols, HALS, nano-titanium oxides, β-diketones, epoxy-based stabilizers, perchlorate-based stabilizers, and/or amine-based stabilizers.

12. The method according to claim 7, wherein flame retardants are provided in the form of antimony oxide, aluminum oxide, hydrotalcite, magnesium hydroxide, magnesium carbonate, calcium carbonate, zinc borate and/or phosphates, expanded graphites, and brominated or chlorinated softeners.

13. The method according to claim 7, wherein additives are provided in the form of emulsifiers, soaps, antifoaming agents, rheological additives, nanotubes, quantum dots, and/or blowing agents.

14. The method according to claim 1, wherein the drying and gelling of the paste-like compound for producing the porous film take place with an addition of heat at temperatures of between 100° C. and 220° C.

15. The method according to claim 1, wherein the paste-like compound applied to the base travels through a drying oven with a length of 1 to 80 m and a speed of 2 to 80 m/min and the drying and gelling of the paste-like compound produce the porous film.

16. The method according to claim 1, wherein the breathable film obtained has a water impermeability of 0.1 to 60 m.sup.2 pa.sup.−1 w.sup.−1.

17. The method according to claim 1, wherein the breathable film obtained has a mass per unit area of 50 to 2000 g/m.sup.2.

18. The method according to claim 1, wherein the paste-like compound is applied to the base by a reverse coater or a roll coater, by doctor blades, spraying, or printing.

19. The method according to claim 1, wherein the base is removed from the film after the film forms or is composed of a substrate that remains attached to the film after the film forms.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) This invention is explained in greater detail in view of exemplary embodiments shown in the drawings, wherein:

(2) FIG. 1 shows an enlarged section taken through an imitation leather that has been produced using the method according to this invention; and

(3) FIG. 2 shows a section taken through a second embodiment of an imitation leather that has been produced using the method according to this invention.

DETAILED DESCRIPTION OF THE INVENTION

(4) FIG. 1 shows a structure of a multi-layered composite serving as an imitation leather, for example of the kind that can be used as a covering material for seats, such as in automotive interiors.

(5) Starting from a top surface that constitutes or forms the visible side, the individual layers are successively labeled with the reference numerals 1 through 8.

(6) The top layer 1 is composed of, includes or comprises a lacquer layer that determines the feel and sheen and is, for example, based on polyurethane or acrylate, based on PVC or PVDF, or based on aniline-, epoxy- or polyamide polyester, while the layer 2 under this is likewise composed of, includes or comprises a lacquer layer that is, for example, based on acrylate or one of the above-mentioned alternatives and which gives the composite wear resistance.

(7) The layer 3 under this once again a lacquer layer that gives the composite the desired coloring and is therefore usually embodied in the form of a printed layer through the use of suitable pigments.

(8) The next layer 4 is an adhesive layer that can be constructed, for example, on the basis of a lacquer layer containing polyurethane or acrylate. This produces the adhesion of the overlying layers 1 through 3 to the underlying layer 5.

(9) The layer 5 is composed of, includes or comprises a breathable PVC-based film and a foreign material, for example, a foreign polymer based on a polyurethane produced according to the above-explained method and can, for example, have a mass per unit area of 10 to 1000 g/m.sup.2, preferably 120 to 500 g/m.sup.2.

(10) Underneath this is an intermediate layer 6 likewise based on a breathable film that has been produced using the method according to this invention. This intermediate layer can be embodied in the form of a foam, expanding polymer spheres such as Expancell, or can be foamed through the addition of blowing agents, while the layer 5 on top of it and also the adhesive layer 7 underneath it, which will be explained in greater detail below, are embodied in a compact form. The mass per unit area of the foamed intermediate layer 6 lies in a range of approximately 10 to 1000 g/m.sup.2.

(11) Beneath the foamed intermediate layer 6, there is an adhesive layer 7 with a mass per unit area of 50 to 250 g/m.sup.2 that can likewise be composed of, include or comprise a breathable film, produced using the method according to this invention. This layer 7 produces the adhesion to the bottom support layer that is labeled with the reference numeral 8, which can in a known fashion be composed of, include or comprise a textile, a polymer, or a foamed support material. This can be a woven support material, a nonwoven, a screen based on organic or inorganic materials such as mineral wool, glass and carbon fibers, and so forth, possibly also with the addition of electrically conductive fibers in order to counteract an electrostatic charging.

(12) The imitation leather according to FIG. 1 is produced, for example, using the so-called reversal process in which first, the intermediate layer 5 is cured on a substrate, such as an embossed or non-embossed paper web, plastic web, or metal web, heated, and coated with a sequence of an intermediate layer 6, and 7, and the support material 8 and heated, then removed from the substrate, and subsequently coated with the layers 1-4, for example, by rasterizing, doctoring, or spraying.

(13) Through the use of suitable methods such as steel embossing, vacuum embossing, silicone sheet roller embossing, and the like, the imitation leather can also have an applied surface embossing in the form of a leather grain structure in the region of or near its visible side, for example in the region of or near the upper breathable layer 5 and the lacquer layers 1 through 4 on top of it.

(14) FIG. 2 shows an exemplary embodiment, which builds on the exemplary embodiment in FIG. 1 and in which the layer structure from the top, visible side to the layer 8 corresponds to the structure shown in FIG. 1 and will not be explained again separately here in order to avoid repetitions.

(15) Underneath the textile support 8, the exemplary embodiment shown in FIG. 2 is thus bonded by a breathable adhesive layer 9 which can, for example, be printed and includes a suitable pressure-sensitive adhesive containing polyurethane, acrylate, PVC, or PVDF or a pressure-sensitive adhesive based on aniline-, epoxy- or polyester-polyamide—to a subsequently laminated padding layer 10, which can be composed of, include or comprise, for example, a polyurethane foam, a polyolefin foam, or the like and can optionally also be produced using the method according to this invention. Such an additional subsequently laminated padding layer 10 gives such an imitation leather a particularly elastic flexibility of the kind that is desirable, for example, in applications for sun shades, armrests, and the like.

(16) Underneath the padding layer 10, there is an additional textile backing layer 11, which can be composed of, include or comprise, for example, a woven or nonwoven.

(17) These imitation leathers produced using up to 11 layers of films produced using the method according to this invention have outstanding breathability with gas permeabilities in the range from 1 to 200 dm.sup.−2 min.sup.−1, water vapor permeabilities between 0.1 to 200 mg cm.sup.−1 h.sup.−1, water impermeabilities between 2 to 60 m.sup.2 pa.sup.−1 w.sup.−1 with a higher resistance to heat and light as well as wear resistance and are particularly suitable for the production of imitation leathers for automotive interior applications in which the breathability is perceived as particularly comfortable.

(18) The breathability also opens up the possibility of producing wall and ceiling coverings composed of, including or comprising films produced using the method according to this invention, which are extremely rugged, but allow any structural moisture behind the wall or ceiling covering to easily diffuse through the covering, thus effectively preventing structural damage due to the formation of mold and the like.

(19) German Patent Application No. DE 10 2014 103 201.2, filed 11 Mar. 2014 and German Patent Application No. DE 10 2014 110 813.2, filed 30 Jul. 2014 the priority documents corresponding to this invention, to which a foreign priority benefit is claimed under Title 35, United States Code, Section 119, and its entire teachings are incorporated, by reference, into this specification.