SOFT PVC FILMS WITH LOW COFFEE STAINING

Description

[0001] The invention relates to a soft PVC film or a multilayer composite with at least one layer made of the soft PVC film and to processes for producing the soft PVC film or the multilayer composite and to their use.

[0002] Soft PVC films are widely used in artificial leather, for example, in automotive and home applications. The color palette of these products has trended toward increasingly lighter variants in recent years.

[0003] One challenge here is the soiling behavior of these films or multilayer composite systems. To evaluate the soiling behavior of such systems, a number of soiling tests are available that test the soiling behavior against specific soiling media.

[0004] Generally, there are common soiling media, such as coffee, which in a soiling test must remain on the surface as a stain for over 24 hours and then be removed with a wet cloth. A second example of a common soiling test is based on a textile substrate soiled with soot and oil, the standard fabric EMPA 128. Both tests stress both water-swellable and water-permeable, as well as oil-swellable and oil-permeable layers, and they tend to absorb dyes with corresponding soiling. Thus, in the past, it was only possible to prioritize one soiling test, with the second test sometimes revealing drastic soiling.

[0005] Artificial leather based on soft PVC consists of several layers, which include a top coat, which is usually dyed as a coloring layer, an intermediate coat, which is usually present as a foamed layer to improve the feel, and a lamination coat, which allows the bond to a textile carrier.

[0006] PVC films are usually provided with fillers such as calcium carbonate, stabilizers such as calcium, barium or zinc soaps and perchlorates.

[0007] Coffee consists of roasted coffee beans. The roasting process leads to the oxidation of the coffee bean and the increased formation of carboxyl groups on the surface, as well as migratory, usually brown-colored molecules containing carboxyl groups, such as coffee oils. These are readily soluble in water, especially at elevated temperatures above 60 °C.

[0008] The soiling behavior of conventional soft PVC films and common multi-layer composite systems such as artificial leather, as determined by soiling tests, has proven unsatisfactory. For example, the soiling behavior studies of conventional PVC films described below have shown that coffee stains are visually detectable and that this discoloration is impossible to reverse.

[0009] The object of the invention was, in particular, to provide a soft PVC film or a multilayer composite with at least one layer made of the soft PVC film, wherein the soft PVC film or the multilayer composite, in particular artificial leather, exhibits improved soiling resistance, particularly against coffee stains. Furthermore, improved soiling resistance should be possible both against hydrophilic soils, such as coffee, and against hydrophobic soils, such as oils.

[0010] The inventors have discovered that soiling behavior can be improved based on an understanding of the molecular relationships involved in soil formation, particularly in the case of coffee. Coffee contains carboxyl-containing, migration-capable, usually brown-colored molecules like coffee oils. In particular, it was discovered that the carboxyl groups contained in coffee form complexes with divalent cations present in conventional PVC films, causing the coffee molecules to bind to the solids in the soft PVC matrix, making a coffee stain visually recognizable. Due to the complex formation, this discoloration is impossible to reverse. The soiling behavior is thus triggered by multivalent, particularly divalent, ions, especially calcium ions, in the polymer matrix.

[0011] Accordingly, a soft PVC film or a multilayer composite with at least one layer of the soft PVC film was designed in which the uptake of freely available divalent metal cations can be avoided or at least reduced.

[0012] The invention thus relates to a soft PVC film or a multi-layer composite with at least one layer of the soft PVC film, wherein the soft PVC film contains PVC and at least one plasticizer and further comprises at least one component selected from: i) a fatty acid salt of a monovalent metal cation as a stabilizer; ii) a perchlorate salt of a monovalent metal cation as a stabilizer, wherein the perchlorate salt is supported on a carrier made of a plastic or an inorganic material, wherein the carrier does not contain any divalent metal cations; iii) core-shell particles as a colorant, wherein the core is formed from a pigment and the shell encapsulates the pigment and does not contain any divalent metal cations, wherein the soft PVC film contains a colorant selected from component iii) and / or a colorant different therefrom, and wherein the proportion of divalent metal cations not encapsulated by a shell material in the soft PVC film is less than 0.1% by weight.

[0013] Through the targeted use of monovalent ions such as potassium and sodium, for example by employing a corresponding fatty acid salt and / or perchlorate salt, the soiling behavior of the PVC film or of the PVC film contained in a multilayer composite, e.g., as a cover film, could be improved. Alternatively or additionally, the carrier, in particular powder carrier, of the perchlorate stabilizer was converted to a polymer base, such as PVC, or an inorganic material that does not contain divalent metal cations. When pigments are used, depending on the pigment, encapsulation of the pigment in the form of core-shell particles can also improve soiling behavior. The result was a soft PVC film or a multilayer composite containing this film, in particular artificial leather, which exhibited significantly better soiling behavior.

[0014] Within the scope of the invention, it was also discovered that due to the low soiling tendency of the inventive soft PVC film, e.g., as a cover film in a multi-layer composite such as synthetic leather, with aqueous systems such as coffee, an oil-repellent aqueous coating could be used in combination with the PVC film. This combination proved to be very helpful, as an improvement in soiling behavior could be achieved in both coffee and soot-oil soiling and cleaning tests.

[0015] The soiling behavior of the soft PVC films according to the invention and multilayer composite systems containing this film, in particular artificial leather, was also evaluated in long-term tests, with no deterioration observed over time.

[0016] The invention is explained in detail below.

[0017] The invention relates to a soft PVC film according to the invention and a multilayer composite containing at least one layer of the soft PVC film according to the invention. The following information on the soft PVC film according to the invention naturally applies equally to the at least one soft PVC film contained in the multilayer composite according to the invention, in particular synthetic leather.

[0018] The soft PVC film according to the invention contains polyvinyl chloride, referred to here as usual by the abbreviation PVC. It may contain one or more types of PVC. Commercially available PVC types or mixtures thereof can be used. The PVC can be, for example, at least one emulsion PVC (E-PVC), e.g., with a K value of 65 to 90, preferably 70 to 80, at least one suspension PVC (S-PVC), including microsuspension PVCs, or mixtures of the aforementioned PVC types. The PVC is preferably or comprises E-PVC.

[0019] The proportion of PVC in the soft PVC film can vary widely and can be, for example, in the range of 20 to 80 wt.%, preferably 20 to 60 wt.%, based on the total weight of the soft PVC film.

[0020] The plasticized PVC film according to the invention further contains at least one plasticizer. It may contain one plasticizer or a mixture of two or more plasticizers. Plasticizers commonly used in the field and known to those skilled in the art can be used.

[0021] Examples of suitable plasticizers are phthalic acid esters, such as dioctyl terephthalate, linear undecyl phthalate, diisodecyl phthalate (DIUP) and diethylhexyl phthalate (DEHP), esters of aliphatic dicarboxylic acids or higher carboxylic acids, such as adipates, sebacates, citrates and 1,2-cyclohexanedicarboxylic acid diisononyl ester (DINCH), epoxidized oils, e.g. epoxidized soybean oil, trimellitates, polyesters, phosphoric acid esters, fatty acid esters, terephthalic acid esters, plasticizers based on glycol, oligoglycol or polyethylene glycol, castor oil-based plasticizers, chlorinated or brominated plasticizers, sulfate-based plasticizers, polymeric plasticizers, ionic liquids and mixtures of two or more of these plasticizers.

[0022] The total content of plasticizer in the soft PVC film can, for example, be in the range of 40 to 150 parts by weight, preferably 60 to 120 parts by weight, per 100 parts by weight of PVC.

[0023] It was shown that the type of plasticizer, such as phthalates, trimellitates, or polymeric plasticizers, as well as the PVC types used, such as E-PVC types, had only a minor influence on soiling behavior. Nevertheless, the following correlation was observed: When using a trimellitate as a plasticizer, improved soiling behavior was observed compared to using a phthalate as a plasticizer.

[0024] The soft PVC film according to the invention further comprises at least one component selected from: i) a fatty acid salt of a monovalent metal cation as a stabilizer; ii) a perchlorate salt of a monovalent metal cation as a stabilizer, wherein the perchlorate salt is supported on a carrier made of a plastic or an inorganic material, wherein the carrier does not contain any divalent metal cations; iii) core-shell particles as a coloring agent, wherein the core is formed from a pigment and the shell encapsulates the pigment and does not contain any divalent metal cations and agents, and wherein in the soft PVC film the proportion of divalent metal cations that are not encapsulated by a shell material is less than 0.1% by weight.

[0025] The optional component i) is a fatty acid salt of a monovalent metal cation, which can serve as a stabilizer in the soft PVC film. One or more fatty acid salts of a monovalent metal cation can be used as the fatty acid salt of a monovalent metal cation.

[0026] In conventional soft PVC films, metal soaps, i.e., fatty acid salts of polyvalent, especially divalent, metal cations, especially calcium or zinc ions, are typically used as stabilizers. The fatty acid salt of a monovalent metal cation used in the invention does not contain any polyvalent cations. Therefore, the soft PVC film preferably does not contain fatty acid salts containing polyvalent, especially divalent, metal cations (metal soaps).

[0027] The monovalent metal cation of the fatty acid salt of a monovalent metal cation is preferably sodium and / or potassium.

[0028] The fatty acid of the fatty acid salt can, for example, contain at least 6 carbon atoms, preferably 6 to 21 carbon atoms, particularly preferably 12 to 18 carbon atoms. Examples of suitable fatty acid salts are laurates and stearates, e.g., sodium laurate, potassium laurate, sodium stearate, potassium stearate, or combinations thereof.

[0029] The proportion of fatty acid salt of a monovalent metal cation in the soft PVC film, if present, can be, for example, in the range of 0.1 to 10 parts by weight, preferably 0.2 to 6 parts by weight, more preferably 0.4 to 4 parts by weight, per 100 parts by weight of PVC. The proportion refers to the total content of fatty acid salt of a monovalent metal cation in the soft PVC film.

[0030] The optional component ii) is a perchlorate salt of a monovalent metal cation as a stabilizer, wherein the perchlorate salt is supported on a carrier made of a plastic or an inorganic material, wherein the carrier does not contain divalent metal cations.

[0031] Contrary to expectations, supported and unsupported perchlorate-based stabilizers proved unsuitable bleaching agents for coffee stains in general and thus had no effect on reducing the discoloration caused by the perchlorate itself as an oxidizing agent. However, it has been shown that supported perchlorate-based stabilizers containing monovalent metal cations, provided the carrier does not contain divalent metal cations, can reduce existing discoloration. Unsupported perchlorates are usually dissolved in polyethylene oxides or polyethylene glycols (PEGs) at a concentration of up to 15%. PEGs usually reduce the thermal properties of PVC and are prone to surface migration; for these reasons, they are not used in the formulation.

[0032] As an optional perchlorate system, a perchlorate salt of a monovalent metal cation supported on a carrier was used according to the invention. The monovalent metal cation of the perchlorate salt is preferably sodium and / or potassium. Thus, the perchlorate salt used is preferably sodium perchlorate and / or potassium perchlorate.

[0033] The perchlorate salt is supported on a carrier made of a plastic or an inorganic material, the carrier not containing any divalent metal cations. PVC is the preferred plastic for the carrier. Examples of suitable inorganic materials as carriers include silicon dioxide or zeolite. As mentioned, the carrier does not contain any divalent metal cations.

[0034] In a particularly preferred embodiment, the optional component ii) is a perchlorate salt of a monovalent metal cation as a stabilizer, wherein the perchlorate salt is supported on a PVC carrier. This PVC can be identical to or different from the PVC of the film. In tests, microsuspension and suspension types have proven particularly advantageous because they do not have an open-pore structure like E-PVC types and thus enable a better stabilizing effect as well as a bubble-free film. A perchlorate stabilizer supported on a PVC carrier proved to be ideal. Even after soiling tests carried out, in particular with coffee stains, e.g. based on the standard soiling DIN EN 15973:2011-05, almost no discoloration was detectable, with Delta E values ​​below 1 being determined. The PVC of the PVC carrier can be, for example, E-PVC, but is preferably suspension PVC or microsuspension PVC.

[0035] The coffee test, based on the standard soiling standard DIN EN 15973:2011-05, is carried out as follows: 2.5 g of instant coffee is added to 240 g of demineralized water. The water has a temperature of 60-80°C before mixing. The solution is applied to the soft PVC film or multi-layer composite (e.g., substrate, film, or artificial leather) using a 2 ml pipette. After a contact time of 24 hours at room temperature (approx. 23°C), half of the soiled area is cleaned with a cotton cloth and a soap solution (0.05% Texapon N70). The Delta E value (color difference, measured in the Lab color space) of the treated area is then determined using a colorimeter in comparison to an unsoiled area of ​​the film.

[0036] The proportion of perchlorate salt (due to legal hazard classes, the maximum available concentration is 20 wt.% in solid medium) of a monovalent metal cation in the carrier as described above can be, for example, 0.2 to 20 parts by weight, preferably 1 to 10 parts by weight, per 100 parts by weight of carrier, wherein the carrier is, for example, PVC, such as emulsion PVC, suspension PVC, microsuspension PVC, or silicon dioxide. It is understood that the weight of the carrier refers to the carrier without the perchlorate salt. The carrier supported with the perchlorate salt of a monovalent metal cation as described above can then be added, for example, in an amount of 0.1 to 20 parts by weight per 100 parts by weight of PVC to the mixture from which the soft PVC film is formed.

[0037] The proportion of perchlorate salt of a monovalent metal cation (without taking into account the carrier), if present, in the soft PVC film can be, for example, 0.001 to 5 parts by weight of perchlorate salt (without corresponding carrier), preferably 0.01 to 3 parts by weight, per 100 parts by weight of PVC.

[0038] In a particularly preferred embodiment, the soft PVC film according to the invention contains perchlorate salt of a monovalent metal cation as a stabilizer, wherein the perchlorate salt is supported on a carrier made of a plastic or an inorganic material, wherein the carrier does not contain any divalent metal cations (component ii).

[0039] Heat stabilization of the soft PVC film by a perchlorate stabilizer was found to be sufficient. Additional stabilization, e.g., by the stabilizers according to component i), is therefore not absolutely necessary. Additional stabilization of multilayer composite systems according to the invention, such as artificial leather, can be ensured, for example, by incorporating calcium and zinc soaps, as well as corresponding additives, such as beta-diketones, sterically hindered and unhindered phenols, e.g., the Irganox types, or epoxides, in layers adjacent to the soft PVC film, such as an intermediate layer formed as a foam layer. A combination of the stabilizers according to component i) and component ii) in the soft PVC film is, of course, also possible.

[0040] The optional component iii) consists of core-shell particles as the coloring agent, with the core consisting of a pigment and the shell encapsulating the pigment and containing no divalent metal cations. One type of core-shell particle or mixtures of two or more different types of core-shell particles can be used.

[0041] The pigment forming the core is a coloring agent and serves to color the soft PVC film. It can be a conventional pigment used in the field for coloring. The pigment is preferably an inorganic pigment, preferably containing a polyvalent metal ion, e.g., a divalent and / or trivalent metal ion. Examples of suitable pigments are iron oxide, e.g., Fe 2 O 3 , FeO(OH), BaCrO 4 , and / or BiVO 4 . It can generally be a standard pigment protected by a shell system.

[0042] The core-shell particle further contains a shell that does not contain any divalent metal cations. Preferably, it also contains no trivalent metal cations. The shell surrounds the core or pigment, thereby encapsulating the pigment. Encapsulation means that the shell prevents the metal ions contained in the pigment from escaping and migrating into the soft PVC matrix. The shell is preferably transparent or at least translucent.

[0043] The shell of the core-shell particles can be formed from an inorganic material, preferably silicon dioxide or aluminum oxide, or an organic polymer, preferably a polyolefin.

[0044] The soft PVC film according to the invention may contain only one of the three components i), ii) or iii), or a combination of two or all three components: Component i) and component ii); component i) and component iii); component ii) and component iii); or component i) and component ii) and component iii).

[0045] As stated, the use of component i) alone or in combination with component ii) and / or component iii) is preferred.

[0046] The proportion of core-shell particles as described above, if present, may be, for example, 0.01 to 25 parts by weight, preferably 0.01 to 10 parts by weight, per 100 parts by weight of PVC.

[0047] The soft PVC film contains a colorant. This can be the optional core-shell particles according to component iii) and / or at least one other colorant.

[0048] It is preferred that all pigment particles in the soft PVC film are coated and thus present as core-shell particles.

[0049] Examples of coloring agents other than the core-shell particles according to component iii) may be, for example, inorganic pigments which do not contain polyvalent metal cations, such as carbon black, inorganic dyes which do not contain free uncomplexed polyvalent metal cations, such as copper phthalocyanine, organic dyes such as quinacridone or diketopyrrolopyrrole, and organic pigments such as ß-naphthol pigments or azo pigments.

[0050] The plasticized PVC film according to the invention may optionally further contain one or more other additives that are customary in the field. Examples of suitable further additives are matting agents, quantum dots, fillers, flow control agents, defoamers, lubricants, rheology aids, thickeners, crosslinkers, light stabilizers, surface modifiers, stabilizers, reinforcing agents such as fibers, flame retardants, blowing agents (both chemical and physical), surfactants, and / or biocides. The skilled person can select suitable further additives depending on the intended use.

[0051] It is preferred that the additives used are additives that do not contain divalent metal cations. Optionally, additives containing divalent metal ions can also be used if they are encapsulated by a shell material, e.g., in the form of core-shell particles, with the additive in question forming the core and the shell forming the shell material.

[0052] For example, the soft PVC film preferably does not contain any fillers containing a divalent metal cation, in particular Ca 2+< or Zn 2+< , such as calcium carbonate or zinc oxide. Suitable fillers include cellulose or silicon dioxide. However, the soft PVC film can also be free of fillers. Suitable flame retardants include various phosphates, such as ammonium phosphate, or expandable graphite. Suitable stabilizers that differ from the stabilizers according to component i) and component ii) include sterically hindered and unhindered phenols (e.g., Irganox types), UV stabilizers, in particular HALS, β-diketones, epoxy-based stabilizers, and / or amine-based stabilizers.

[0053] The soft PVC film according to the invention contains less than 0.1 wt.% of freely available divalent metal cations or preferably no freely available divalent metal cations, in particular only low concentrations of freely available Ca 2+< ions, Mg 2+< ions and / or Zn 2+< ions or in particular no freely available Ca 2+< ions, Mg 2+< ions and / or Zn 2+< ions.

[0054] Freely available divalent metal cations are understood to be divalent metal cations that are components of compounds, salts, or other materials contained in the soft PVC film, unless the compound, salt, or other material containing divalent metal cations is encapsulated by a coating material. Encapsulation with the coating material means that migration of the divalent metal cation from the compound, salt, or other material into the matrix of the soft PVC film is prevented by the coating material.

[0055] An example of an encapsulating shell material is the shell of the core-shell particles described above. Suitable materials for the shell material are the materials mentioned above for this shell, so reference is made to them. It is understood that, like the shell, the shell material does not contain any divalent metal cations.

[0056] In the soft PVC film according to the invention, the proportion of divalent metal cations which are not encapsulated by a shell material is less than 0.1 wt.%, preferably less than 0.01 wt.%, particularly preferably less than 0.001 wt.%, based on the total weight of the soft PVC film, wherein the soft PVC film is more preferably free of divalent metal cations which are not encapsulated by a shell material.

[0057] In a further preferred embodiment, the total proportion of Ca 2+< ions, Mg 2+< ions and / or Zn 2+< ions in the soft PVC film that are not encapsulated by a shell material is less than 0.1 wt.%, preferably less than 0.01 wt.%, particularly preferably less than 0.001 wt.%, based on the total weight of the soft PVC film, wherein the soft PVC film is more preferably free of Ca 2+< ions, Mg 2+< ions and / or Zn 2+< ions that are not encapsulated by a shell material.

[0058] The soft PVC film according to the invention can be a compact or foamed soft PVC film, with a compact or non-foamed soft PVC film generally being preferred.

[0059] The soft PVC film according to the invention can, for example, have a basis weight in the range from 5 to 1200 g / m 2< , preferably 50 to 500 g / m 2< , in particular when it is contained as a layer or cover layer in a multi-layer composite, such as, for example, artificial leather.

[0060] The soft PVC film according to the invention can be used as a stand-alone film, e.g., in the form of a sheet or covering, e.g., a floor covering or a wall covering, or as a component of a multilayer composite, e.g., as artificial leather, in which the film is combined with other layers. The multilayer composite can contain one or more soft PVC films according to the invention.

[0061] The soft PVC film according to the invention and the multilayer composite according to the invention, in particular artificial leather, are suitable, for example, for indoor and outdoor applications, for furniture and applications in the field of vehicles, in particular automobiles, or generally in industry, such as furniture films, floor coverings, wall coverings, automotive headliners, automotive interiors and / or seating materials, including automotive seats, as well as for corresponding articles in the mobility or contract sector, such as hotel chains, cinemas, home applications, aircraft, buses and trains, cruise ships (nautical application).

[0062] In a preferred embodiment, the multilayer composite according to the invention is a synthetic leather. The soft PVC film is preferably provided in the synthetic leather as a cover layer, in particular as a color-imparting cover layer. The soft PVC film can be present as a foamed layer or, preferably, as a solid layer.

[0063] Synthetic leather is a multi-layer composite comprising, in this order, a top layer, which is usually dyed as a coloring layer; an intermediate layer, which is usually a foamed layer to improve the feel; a backing layer; and a textile carrier. The backing layer serves to bond the textile carrier. Additional layers may be included. The top layer, intermediate layer, and backing layer are often referred to as the top coat, intermediate coat, and backing coat, respectively. In use, the synthetic leather is usually applied to a substrate with the textile carrier side facing the visible side.

[0064] The multi-layer composite material used as artificial leather is usually given a leather grain, textile grain, or technical finish using a conventional graining process. Common graining processes can be used, such as steel stamping, vacuum stamping, or silicone stamping.

[0065] In a preferred embodiment, the soft PVC film or the multilayer composite, in particular the artificial leather, is provided with one or more lacquer layers, which in the case of the multilayer composite, in particular the artificial leather, are arranged above the cover layer. One lacquer layer is preferably an oil-repellent lacquer layer. Other lacquer layers can serve, for example, to adjust the feel, appearance, e.g., gloss, and / or abrasion resistance. In general, the lacquer layers are also suitable for protecting the soft PVC film or the multilayer composite. The lacquer layers can be, for example, transparent, translucent, colored, or matte.

[0066] For coating with an oil-repellent coating layer, an aqueous oil-repellent coating is preferred. The oil-repellent coating layer can be based on acrylates, polyurethanes, polyvinylidene fluoride (PVDF), and / or silicones, for example.

[0067] Since the soiling behavior of the multi-layer composite, particularly synthetic leather, can be significantly improved by using the soft PVC film according to the invention, especially as a top layer, compared to aqueous systems such as coffee, it is possible to use an oil-repellent lacquer layer in combination with the soft PVC film. This enables improved soiling behavior in soiling and cleaning tests, such as tests with coffee stains based on DIN EN 15973:2011-05 as described above and / or the standard fabric EMPA 128 based on ISO 26082-1, both for hydrophilic soils, e.g., coffee, and hydrophobic soils, e.g., oil.

[0068] Overall, a soft PVC film or multilayer composite with improved soiling behavior is obtained, particularly with regard to coffee stains. Measurement with a colorimeter showed that the color difference, measured in the Lab color space ΔE, can be reduced. For example, with the soft PVC films or multilayer composite systems according to the invention, values ​​of ΔE < 1, preferably ΔE < 0.5, were obtained in the coffee test based on the standard soiling DIN EN 15973:2011-05 as described above. The value ΔE (delta E) refers to an unsoiled film surface as a reference, i.e. the ΔE value is the difference between the unsoiled surface and the soiled and cleaned surface according to the coffee test.

[0069] The soft PVC film or multilayer composite according to the invention as described above is preferably obtainable according to the process according to the invention described below.

[0070] The invention further relates to a process for producing a soft PVC film according to the invention or a multilayer composite according to the invention as described above, comprising a) mixing the components of the PVC film, comprising PVC and at least one plasticizer and at least one component selected from: i) a fatty acid salt of a monovalent metal cation as a stabilizer; ii) a perchlorate salt of a monovalent metal cation as a stabilizer, wherein the perchlorate salt is supported on a carrier made of a plastic or an inorganic material, wherein the carrier does not contain divalent metal cations;iii) core-shell particles as coloring agent, wherein the core is formed from a pigment and the shell encapsulates the pigment and does not contain any divalent metal cations, to form a mixture, wherein the mixture contains a coloring agent as a component which is selected from component iii) and / or a coloring agent different therefrom, b) applying the formed mixture to a substrate or shaping the formed mixture and c) optionally drying and / or gelling the applied or shaped mixture to form the soft PVC film. ;

[0071] All the above statements regarding the inventive soft PVC film or multilayer composite with at least one layer of the soft PVC film, such as examples and preferred embodiments, naturally apply correspondingly to the inventive process, in particular with regard to the components, i.e., PVC, plasticizer, components i), ii), iii), the optional additional additives, and the described embodiments of the soft PVC film and the multilayer composite. Reference is therefore made to these statements.

[0072] According to step a) of the process according to the invention, a mixture is formed by mixing the components of the soft PVC film. The components comprise at least PVC and at least one plasticizer, and at least one component selected from components i), ii), and iii) as described above. The mixture may further optionally contain, as further components, one or more further additives as described above.

[0073] The mixture may be free of solvents or may contain one or more solvents, e.g., water and / or an organic solvent. The mixture preferably contains one or more solvents, preferably water and optionally one or more solvents, whereby the resulting mixture may be in the form of a pasty mass.

[0074] The components can be mixed in standard mixing equipment. Mixing can take place at ambient temperature or with heating. The order of addition of the components is arbitrary. It is often convenient to first add the plasticizer to the mixing equipment and then add the other components.

[0075] According to step b) of the process according to the invention, the mixture formed is applied to a substrate or brought into the desired shape by a molding process.

[0076] For film production by molding the resulting mixture, the mixture can be formed into the desired shape using a calender or extruder, for example, to obtain the soft PVC film. These are common molding processes for thermoplastics. Solvent-free mixtures, for example, are suitable for this purpose.

[0077] Common methods can be used to apply the mixture to a substrate, such as brushing, knife coating, spraying, printing, or pouring. Mixtures containing water and / or at least one organic solvent, for example, in the form of a paste, are preferred for this purpose.

[0078] In an optional step c), which is carried out particularly when applying the mixture to a substrate, the mixture is dried and / or gelled, usually dried and gelled. The drying and / or gelling of the applied mixture usually takes place at an elevated temperature, e.g., at a temperature in the range of 100 to 250 °C. Gelling means that the mixture gels, i.e., the PVC grain is swollen in the plasticizer, so that the chains intercalate and a gel forms.

[0079] For the production of a multilayer composite based on the obtained soft PVC film on the substrate, a direct coating process or a reversal process can be used, for example.

[0080] In the direct coating process, the formed soft PVC remains on the substrate, with the substrate forming the remainder of the multilayer composite. In the reversal process, the remaining layers of the multilayer composite are applied to the formed soft PVC film in the usual way, and the substrate is then removed from the formed composite. In the reversal process, a grain tape or release paper, for example, can be used as the substrate. If the soft PVC film forms another layer rather than the top layer, it is naturally applied at a different location within the composite.

[0081] The resulting multi-layer composite can be coated with one or more layers of lacquer on the top layer. As mentioned, coating with an oil-repellent lacquer is a preferred embodiment.

[0082] If the multi-layer composite is synthetic leather, the synthetic leather is generally given a leather grain, textile grain, or technical finish using a conventional graining process. Common graining processes can be used, such as steel stamping, vacuum stamping, or silicone stamping.

[0083] In a preferred embodiment of the process according to the invention, the mixture prepared in step a) comprises water and / or an organic solvent, preferably water, in step b) the mixture is applied to a substrate and in step c) the applied mixture is dried and / or gelled at an elevated temperature, preferably at a temperature in the range of 100 to 250 °C, to form the PVC film.

[0084] The invention also relates to the use of the inventive soft PVC film or multilayer composite as described above as an anti-soiling surface, particularly against coffee stains, wherein the multilayer composite is preferably a synthetic leather. This is made possible by the improved soiling behavior of the inventive soft PVC films and multilayer composite systems.

[0085] The invention will now be further explained based on test results. Examples

[0086] Extensive measurements have shown that carboxyl groups contained in coffee can form complexes, particularly with divalent ions such as calcium, barium, or zinc ions. This leads to the binding of the colored coffee molecules to the solids in the soft PVC matrix, making a coffee stain visually detectable. Due to the complex formation, this discoloration is impossible to reverse.

[0087] All quantities given are by weight unless otherwise stated. Reference example 1

[0088] For example, in a formulation with an E-PVC, a plasticizer content of 80 parts of a common phthalate and a calcium-based stabilizer, a dependence of the color intensity on the content of additional calcium carbonate filler was demonstrated: The following formulation was used for the cover film: 100 parts E-PVC 80 parts plasticizer (DIUP = diisodecyl phthalate) 4 parts perchlorate-based stabilizer on calcium-based carrier 10 parts pigment preparation (carbon black and titanium dioxide) 0-10 parts filler (calcium carbonate)

[0089] The paste is mixed in a conventional dissolver at a peripheral speed of 10-24 m / s until homogeneous. The viscosity is in the range of 1000-10000 mPas. The paste is then applied to a substrate surface, such as coated paper, using a knife blade at a thickness of 200 g / m² and gelled at a temperature of 180 °C for 40 seconds. A foam layer is then applied.

[0090] As the proportion of calcium ions in the matrix increases, the discoloration in the coffee test increases.

[0091] The coffee test, based on the standard soiling standard DIN EN 15973:2011-05, is carried out as follows: 2.5 g of instant coffee is added to 240 g of demineralized water. The water has a temperature of 60-80°C before mixing. The solution is applied to the soft PVC film or multi-layer composite (e.g., substrate, film, or artificial leather) using a 2 ml pipette. After a contact time of 24 hours at room temperature, half of the soiled area is cleaned with a cotton cloth and a soap solution (0.05% Texapon). The Delta E value (color difference, measured in the Lab color space) of the treated area compared to a non-soiled area as a reference is then determined using a colorimeter. Reference example 2

[0092] A soft PVC film was produced according to Reference Example 1, using the following formulation for the cover film: 100 parts E-PVC 100 parts plasticizer (Jayflex L11P = linear undecyl phthalate) 2 parts ASM 711 (stabilizer system from Baerlocher, which is based on calcium hydroxide and calcium oxide with appropriate amounts of perchlorate) 10 parts pigment preparation (carbon black and titanium dioxide) 0-8 parts Omya3 (calcium carbonate) according to the table below

[0093] The formulation was mixed into a homogeneous paste in a conventional dissolver at a peripheral speed of 10-24 m / s. The paste was then applied to a substrate surface, such as coated paper, using a knife blade at a thickness of 500 µm and gelled at a temperature of 200 °C.

[0094] The resulting soft PVC film was subjected to a coffee test as in Example 1, resulting in discoloration. The color values ​​were then determined in the Delta L, A, B color space. The reference in each case was the unsoiled film surface, i.e., the delta E is the difference between the unsoiled surface and the soiled and cleaned surface according to the coffee test. plasticizers stabilizer filler parts filler DL* There* Db* DG DE* Jayflex L11P ASM 711 - 0 -3,46 0 5,79 -1,1 6,74 Jayflex L11P ASM 711 Omya3 2 -4,17 -0,06 6,89 -0,9 8,05 Jayflex L11P ASM 711 Omya3 4 -4,53 -0,04 7,35 -1 8,63 Jayflex L11P ASM 711 Omya3 8 -5,28 0,03 8,49 -1 9,99

[0095] In the previously shown study, a calcium-based stabilizer system was used, which resulted in a film without filler showing high discoloration despite all expectations.

Claims

1. Soft-PVC film or multilayer composite having at least one layer of the soft-PVC film, where the soft-PVC film contains PVC and at least one plasticizer and further comprises at least one component selected from: i) a fatty acid salt of a monovalent metal cation as stabilizer; ii) a perchlorate salt of a monovalent metal cation as stabilizer, where the perchlorate salt is supported on a support made of a plastic or an inorganic material, where the support does not contain any divalent metal cations; iii) core-shell particles as colouring agent, where the core is formed from a pigment and the shell encapsulates the pigment and does not contain any divalent metal cations, where the soft-PVC film contains a colouring agent which is selected from component iii) and / or a colouring agent different therefrom and where the proportion of divalent metal cations not encapsulated by a casing material in the soft-PVC film is less than 0.1% by weight.

2. Soft-PVC film or multilayer composite according to Claim 1, where the proportion of divalent metal cations not encapsulated by a casing material in the soft-PVC film is less than 0.01% by weight, preferably less than 0.001% by weight, where the soft-PVC film is more preferably free of divalent metal cations not encapsulated by a casing material, and / or where the total proportion of Ca2+ ions, Mg2+ ions and / or Zn2+ ions not encapsulated by a casing material in the soft-PVC film is less than 0.1% by weight, preferably less than 0.01% by weight, more preferably less than 0.001% by weight, where the soft-PVC film is more preferably free of Ca2+ ions, Mg2+ ions and / or Zn2+ ions not encapsulated by a casing material.

3. Soft-PVC film or multilayer composite according to either of the preceding claims, where - the monovalent metal cation of the fatty acid salt is sodium and / or potassium and / or - the monovalent metal cation of the perchlorate salt is sodium and / or potassium and / or - the shell of the core-shell particles is formed from an inorganic material, preferably silicon dioxide or aluminium oxide, or an organic polymer, preferably a polyolefin.

4. Soft-PVC film or multilayer composite according to any of the preceding claims, where component ii) is present in the soft-PVC film.

5. Soft-PVC film or multilayer composite according to any of the preceding claims, where the support on which the perchlorate salt of a monovalent metal cation is supported is formed from a plastic selected from PVC or an inorganic material selected from silicon dioxide or zeolite, where a PVC support is preferred, where the PVC of the support is particularly preferably a suspension PVC or a microsuspension PVC.

6. Soft-PVC film or multilayer composite according to any of the preceding claims, where the proportion of perchlorate salt of a monovalent metal cation in the support is 0.2 to 20 parts by weight, preferably 1 to 10 parts by weight, per 100 parts by weight of support, where the support is preferably a PVC support.

7. Soft-PVC film or multilayer composite according to any of the preceding claims, where - the proportion of fatty acid salt of a monovalent metal cation, if present, is 0.1 to 10 parts by weight, preferably 0.2 to 6 parts by weight, more preferably 0.4 to 4 parts by weight, per 100 parts by weight of PVC, and / or - the proportion of perchlorate salt of a monovalent metal cation, if present, is 0.001 to 5 parts by weight, preferably 0.01 to 3 parts by weight, per 100 parts by weight of PVC, and / or - the proportion of core-shell particles, if present, is 0.01 to 25 parts by weight, preferably 0.01 to 10 parts by weight, per 100 parts by weight of PVC.

8. Soft-PVC film or multilayer composite according to any of the preceding claims, where the multilayer composite is an artificial leather, where the soft-PVC film is preferably provided as a colour-imparting top layer.

9. Soft-PVC film or multilayer composite according to any of the preceding claims, where the soft-PVC film or the multilayer composite, in particular artificial leather, is coated with one or more coating layers, where a coating layer is preferably an oil-repellent coating layer.

10. Soft-PVC film or multilayer composite according to any of the preceding claims having improved soiling behaviour, particularly in relation to coffee stains.

11. Soft-PVC film or multilayer composite according to any of the preceding claims, obtainable by a process according to Claim 12 or 13.

12. Process for producing a soft-PVC film or a multilayer composite according to any of Claims 1 to 10, comprising a) mixing the components of the PVC film, comprising PVC and at least one plasticizer and at least one component selected from: i) a fatty acid salt of a monovalent metal cation as stabilizer; ii) a perchlorate salt of a monovalent metal cation as stabilizer, where the perchlorate salt is supported on a support made of a plastic or an inorganic material, where the support does not contain any divalent metal cations; iii) core-shell particles as colouring agent, where the core is formed from a pigment and the shell encapsulates the pigment and does not contain any divalent metal cations, to form a mixture, where the mixture contains a colouring agent as a component which is selected from component iii) and / or a colouring agent different therefrom, b) applying the formed mixture to a substrate or shaping the formed mixture and c) optionally drying and / or gelling the applied or shaped mixture to form the soft-PVC film.

13. Process according to Claim 12, where the mixture produced in step a) comprises water and / or an organic solvent, preferably water, in step b) the mixture is applied to a substrate and in step c) the applied mixture is dried and / or gelled at an elevated temperature, preferably at a temperature in the range of 100°C to 250°C, in order to form the PVC film.

14. Use of a soft-PVC film or a multilayer composite according to any of Claims 1 to 11 as an anti-dirt surface, particularly in relation to coffee stains, where the multilayer composite is preferably an artificial leather.