Antistatic stretch film

Abstract

The present invention relates to an antistatic stretch film, a method for making the same, and the use of certain heat-activated polyurethanes to make the film.

Description

[Technical Field]

[0001] The present invention relates to an antistatic film. [Background technology]

[0002] Antistatic films are known and are described, for example, in EP 0829520, EP 2 170 972, WO 2009 / 086249 and EP 2 058009, as well as antistatic additives to polymers, such as those outlined in US 2016 / 0260516 A1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] EP 0829520 [Patent Document 2] EP 2 170 972 [Patent Document 3] WO 2009 / 086249 [Patent Document 4] EP 2 058009 [Patent Document 5] US 2016 / 0260516 A1 Summary of the Invention [Problem to be solved by the invention]

[0004] On the other hand, the disadvantage of antistatic films on the market is that the films do not meet the mechanical requirements for stretching, or when the films are stretch films (stretched films), the electrical resistance is too high for widespread use. In other words, there is a long-standing unmet need in the market for the development of films, preferably stretched films, which have sufficient mechanical properties and at the same time good antistatic properties. [Means for solving the problem]

[0005] Surprisingly, this problem could be solved by a film according to the characteristic features of claim 1. Another aspect of the invention is the use of a thermoplastic polyurethane for the film according to claim 1, and yet another aspect is a method for producing this film. DETAILED DESCRIPTION OF THE INVENTION

[0006] In a first embodiment, the present invention provides: A film, preferably a stretchable film, comprising at least two layers, Layer A and Layer B, each layer having an inner surface in contact with the other layer and an outer surface opposite the inner surface; Layer A comprises a Polymer 1 composition; Layer B comprises a thermoplastic polyurethane composition (TPU composition), and optionally a Polymer 2 composition; The polyurethane in the TPU composition is ○Organic diisocyanates, a polyol comprising a diol A and a diol B, wherein the diol A comprises ethoxy and propoxy groups and the diol B comprises butoxy groups; chain extenders, and The present invention relates to a film in which the TPU composition comprises a salt, an ionic liquid, or is a mixture of a salt and an ionic liquid.

[0007] The advantages of the film according to the present invention are particularly its good mechanical properties. The film may be stretchable, transparent, and capable of bearing large loads. Due to the layer structure of the present invention, electrical resistance is less affected even when the film is stretched. In addition, the layer structure of the film containing salts or ionic liquids in the TPU composition shows less migration of these antistatic additives, for example, into the adhesive layer or from layer B to layer A, compared to other antistatic additives used previously.

[0008] Layer A is preferably a film. The polymer composition used in Layer A itself often has insufficient conductivity, even with the addition of a conductivity-enhancing additive. As a result, the film may become electrostatically charged and sparks may occur. On the other hand, the conductivity of Layer A is greatly enhanced by using the thermoplastic polyurethane composition (TPU composition) of Layer B. Therefore, Layer B preferably covers the entire surface of one of Layers A.

[0009] The TPU composition is preferably in the form of a film or net structure, which is preferably present directly on the inner surface of layer A.

[0010] The term "composition" indicates that the composition does not comprise only the respective polymer, but may also comprise other polymer additives, auxiliaries or mixtures thereof.

[0011] In a preferred embodiment according to this embodiment or one of its preferred embodiments, Layer B comprises a thermoplastic polyurethane composition and a polymer 2 composition. The TPU composition is preferably embedded in polymer 2 in the form of a net structure. This net structure is preferably formed by thoroughly mixing the TPU composition with the polymer 2 composition. Thus, the net structure of the TPU composition in the polymer 2 composition is irregular.

[0012] Polymer 2 is preferably a non-polar polymer. Preferably, Polymer 2 is selected to enhance adhesion or compatibility, or both, between Layer B and Layer A.

[0013] In a preferred embodiment, each composition contains an auxiliary or additive, or a mixture thereof. Exemplary preferred auxiliary agents are catalysts, surfactants, flame retardants, nucleating agents, lubricating waxes, dyes, pigments, or stabilizers, or mixtures thereof. Stabilizers are additives that protect polymers from harmful environmental influences, preferably from, for example, oxidation, hydrolysis, light, heat, or discoloration. Exemplary preferred additives are inorganic or organic fillers and reinforcing materials, or mixtures thereof.

[0014] It is important that Layer B completely covers the inner surface of Layer A. For this reason, in a preferred embodiment, Layer B is a film. In another preferred embodiment, Layer B has a net structure. The net structure may be regular or irregular. Preferably, the irregular net structure is derived from the melt spinning process or is the result of the drawing process.

[0015] In other embodiments, including all of the features of the above-described embodiment or preferred embodiments thereof, the film has an elongation at break of greater than 50%, preferably greater than 100%, more preferably greater than 150%, even more preferably greater than 200%, even more preferably greater than 250%, and most preferably greater than 300%, as measured according to DIN ISO 53504, 2017-03. In these embodiments, the maximum elongation when stretched is no more than 500%, no more than 450%, no more than 400%, no more than 350%, no more than 320%, no more than 300%, no more than 250%, no more than 200%, no more than 150%, no more than 100%, or no more than 50%. In other words, a film having these properties is stretchable, a stretchable film, or a stretchable film.

[0016] Preferably, polymer 1 and, if applicable, polymer 2 are independently selected from the group consisting of polystyrene (PS), polyoxymethylene (POM), ethylene vinyl acetate (EVA), acrylonitrile-butadiene-styrene (ABS), thermoplastic polyurethane (TPU), polyvinyl chloride (PVC), polyethylene (PE) and polypropylene (PP), or mixtures thereof.

[0017] More preferably, polymer 1, and, where applicable, polymer 2, are independently selected from the group consisting of flexible polyvinyl chloride (sPVC), thermoplastic polyurethane (TPU), polyethylene (PE), low density polyethylene (LDPE) or linear low density polyethylene (LLDPE), or mixtures thereof.

[0018] More preferably, polymer 1 and, if applicable, polymer 2 are independently selected from the group consisting of thermoplastic polyurethane (TPU), polyvinyl chloride (PVC), polyethylene (PE) and polypropylene (PP), or mixtures thereof.

[0019] In another preferred embodiment, polymer 1 and, if applicable, polymer 2 are independently selected from the group consisting of flexible polyvinyl chloride (PVC) and polyethylene (PE), or a mixture thereof.

[0020] Flexible polyvinyl chloride (sPVC) is polyvinyl chloride (PVC) to which a plasticizer has been added. The plasticizer is preferably added in an amount of more than 10% by weight, more preferably more than 20% by weight, even more preferably more than 30% by weight, more than 40% by weight, and at the same time less than 70% by weight, preferably less than 60% by weight, and more preferably less than 55% by weight, based on the total weight of the polyvinyl chloride. These plasticizers in polyvinyl chloride (PVC) are preferably selected from the group consisting of phthalates, acetyltributyl citrate (TBAC), chlorinated paraffins, adipates, and phosphates, or mixtures thereof.

[0021] In one preferred embodiment of the embodiment outlined above, the polyethylene (PE) is low density polyethylene (LDPE) or linear low density polyethylene (LLDPE). The polyethylene (PE) of polymer 1 is preferably a blend of low density polyethylene (LDPE) and linear low density polyethylene (LLDPE), and optionally polymer 2 is low density polyethylene (LDPE).

[0022] If the Polymer 2 composition comprises a thermoplastic polyurethane, in a preferred embodiment, the recipe of this thermoplastic polyurethane is different from the recipe of the thermoplastic polyurethane composition in which the salt, ionic liquid, or salt and ionic liquid are incorporated.

[0023] In another preferred embodiment, polymer 1, and, if applicable, polymer 2, are independently selected from the group consisting of polyethylene (PE) and polypropylene (PP), or a mixture thereof. Preferably, polymer 1, and, if applicable, polymer 2, are polyethylene (PE). In one preferred embodiment in Layers A and B, no other polymers are included in the film other than the polyethylene (PE) composition and the TPU composition.

[0024] More preferably, polymer 1 and optionally polymer 2 in one of the embodiments outlined above are low density polyethylene (LDPE) or linear low density polyethylene (LLDPE). Preferably, polymer 1 is a blend of low density polyethylene (LDPE) and linear low density polyethylene (LLDPE), and optionally polymer 2 is low density polyethylene (LDPE).

[0025] LDPE: Preferably, the low density polyethylene (LDPE) has a density of 0.90 g / cm, measured according to DIN EN ISO 1183-1:2019, A. 3 and 0.95 g / cm 3 a density between 0.91 g / cm 3 and 0.93 g / cm 3 and most preferably 0.92 g / cm 3 It has a density of

[0026] The melt flow index (MFI, also referred to as melt flow rate MFR) of low-density polyethylene (LDPE) is preferably between 0.5 g / 10 min and 2.0 g / 10 min, more preferably between 0.8 g / 10 min and 1.5 g / 10 min, even more preferably between 0.9 g / 10 min and 1.1 g / 10 min, and most preferably 1.0 g / 10 min, measured at 190°C under a 2.16 kg load according to DIN EN ISO 1133-1:2011.

[0027] Preferably, the Vicat temperature of the low density polyethylene (LDPE) is between 90°C and 100°C, more preferably between 92°C and 99°C, even more preferably between 94°C and 98°C, more preferably between 95°C and 97°C, and most preferably 96°C, measured according to DIN EN ISO 306:2013, A.

[0028] LLDPE: Preferably, the linear low density polyethylene (LLDPE) has a viscosity of 0.90 g / cm, measured according to DIN EN ISO 1183-1:2019, A. 3 and 0.95 g / cm 3 and more preferably 0.91 g / cm 3 and 0.93 g / cm 3 , most preferably 0.92 g / cm 3 is.

[0029] The melt flow index (MFI) of the linear low density polyethylene (LLDPE) is between 0.5 g / 10 min and 2.0 g / 10 min, more preferably between 0.8 g / 10 min and 1.5 g / 10 min, even more preferably between 0.9 g / 10 min and 1.1 g / 10 min, and most preferably 1.0 g / 10 min, at 190°C and 2.16 kg load, measured according to DIN EN ISO 1133-1:2011.

[0030] The Vicat temperature of the linear low density polyethylene (LLDPE) is preferably between 97°C and 107°C, more preferably between 99°C and 105°C, even more preferably between 100°C and 104°C, even more preferably between 101°C and 103°C, and most preferably 102°C, measured according to DIN EN ISO 306:2013, A.

[0031] In preferred embodiments of the LDPE, respectively the LLDPE, these parameters of density, melt flow index, and Vicat temperature are single preferred parameters, or in other preferred embodiments, two of these preferred parameters appear together, or three of these preferred parameters appear together in the preferred LDPE, respectively the LLDPE.

[0032] In a preferred embodiment, the film has a thickness between 1 μm and 1 cm, preferably between 0.001 mm and 1 mm, even more preferably between 0.01 μm and 0.5 mm, more preferably between 0.01 mm and 0.05 mm. In one preferred embodiment, the film is about 0.02 mm. In one preferred embodiment, the major part of the film is Layer A. Layer B and, if applicable, Layer C each preferably, and independently of each other, have a thickness of 0.001 mm to 0.5 mm, preferably between 0.001 and 0.05 mm, more preferably between 0.001 mm and 0.01 mm.

[0033] Thermoplastic polyurethane composition Thermoplastic polyurethane compositions prepared from Diol A and Diol B of the preceding embodiment are further described in US 2016 / 0260516, which is incorporated herein by reference.

[0034] Thermoplastic polyurethane compositions of the embodiments as outlined above, preferred embodiments thereof, comprise a thermoplastic polyurethane, wherein the thermoplastic polyurethane comprises: a) diisocyanates, b) a polyol comprising diol A and diol B, and c) chain extenders; and optionally with the aid of a catalyst, and optionally further comprising additives, auxiliaries, or both, wherein a salt and / or an ionic liquid, preferably an ionic liquid, is included in the composition, and wherein diol A comprises ethoxy and propoxy groups, and diol B comprises butoxy groups.

[0035] Thermoplastic polyurethanes are well known in themselves. They are (a) isocyanate-reactive and (b) are isocyanate-reactive, also known as polyols, and have a molecular weight of 0.5×10 3 g / mol ~ 300 × 10 3 g / mol, and optionally a compound having a number average molecular weight of 0.05×10 3 g / mol~0.499x10 3 g / mol) with a chain extender having a molecular weight of 1000 g / mol, optionally with the aid of a catalyst and / or additive and / or auxiliary.

[0036] Components (a) isocyanate, (b) isocyanate-reactive compound, and (c) chain extender, individually or collectively, are also referred to as building components.

[0037] The diisocyanate is preferably an organic isocyanate. More preferably, the isocyanate is selected from the group consisting of aliphatic, cycloaliphatic, araliphatic and aromatic isocyanates, or a mixture thereof. The isocyanate is preferably selected from the group consisting of tri-, tetra-, penta-, hexa-, hepta- and / or octamethylene diisocyanate, 2-methyl-pentamethylene 1,5-diisocyanate, 2-ethyl-butylene-1,4-diisocyanate, 1,5-pentamethylene diisocyanate (PDI), 1,4-butylene diisocyanate, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethyl-silane. Cyclohexane (isophorone diisocyanate, IPDI), 1,4-bis(isocyanatomethyl)cyclohexane and / or 1,3-bis(isocyanatomethyl)cyclohexane (HXDI), 2,4-paraphenylene diisocyanate (PPDI), 2,4-tetramethylene xylene diisocyanate (TMXDI), 4,4'-, 2,4'- and 2,2'-dicyclohexylmethane diisocyanate (H12 MDI), 1,6-hexamethylene diisocyanate (HDI), 1,4-cyclohexane diisocyanate, 1-methyl-2,4- and / or -2,6-cyclohexane diisocyanate, 2,2'-, 2,4'- and / or 4,4'-diphenylmethane diisocyanate (MDI), 1,5-naphthylene diisocyanate (NDI), 2,4- and / or 2,6-toluene diisocyanate (TDI), 3,3'-dimethyl-diphenyl diisocyanate, 1,2-diphenylethane diisocyanate and / or phenylene diisocyanate, or mixtures thereof.

[0038] More preferably, the isocyanate is an aliphatic diisocyanate, more preferably 4,4'-, 2,4'-, and 2,2'-dicyclohexylmethane diisocyanate (H12 MDI), 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethyl-cyclohexane (isophorone diisocyanate, IPDI), 1,6-hexamethylene diisocyanate (HDI), 1,4-cyclohexane diisocyanate, 1-methyl-2,4- and / or -2,6-cyclohexane diisocyanate, 1,4-bis(isocyanatomethyl)cyclohexane and / or 1,3-bis(isocyanatomethyl)cyclohexane (HXDI), tri-, tetra-, penta-, hexa-, hepta- and / or octamethylene diisocyanate, 2-methyl-pentamethylene 1,5-diisocyanate, 2-ethyl-butylene-1,4-diisocyanate, 1,5-pentamethylene diisocyanate (PDI), 1,4-butylene diisocyanate, or mixtures thereof. A highly preferred isocyanate is 1,6-hexamethylene diisocyanate (HDI).

[0039] As the compound (b) reactive towards isocyanates, it is preferred to use polyesterols or polyetherols, which are also categorized under the term "polyols". Polyetherols are preferred. The number average molecular weight of these polyols is 0.5 x 10 3 kg / mol to 8 × 10 3 kg / mol, preferably 0.6×10 3 g / mol to 5 × 10 3 g / mol, specifically 0.8 × 10 3 g / mol to 3 × 10 3 kg / mol. The polyol preferably has an average functionality in the range of 1.8 to 2.4, preferably 1.9 to 2.2, in particular 1.95 to 2.05. The polyol (b) preferably has only primary hydroxyl groups. Preferred polyols are diols.

[0040] According to the present invention, the polyol comprises at least two diols, diol A and diol B, where diol A comprises ethoxy and propoxy groups, and diol B comprises butoxy groups.

[0041] In a preferred embodiment, the molar percentages of ethoxy, propoxy and butoxy groups in the TPU composition are in each case at least 5 mol %, preferably at least 10 mol %, based on the molar mass of the total polyol, and more preferably at least 25 mol %, more preferably at least 40 mol %, even more preferably at least 60 mol %, and especially preferably at least 65 mol %, of the total polyol.

[0042] Very particular preference is given to a proportion of ethoxy groups in the range from 70 mol % to 75 mol %, a proportion of propoxy groups in the range from 12 mol % to 18 mol %, and a proportion of butoxy groups in the range from 12 mol % to 18 mol %, based on the total polyol.

[0043] Mole percentage determination is performed by 1H NMR according to ASTM D4875-11(2011) Standard Test Methods for Polyurethane Raw Materials: Determination of Polymerized Ethylene Oxide Content of Polyether Polyols.

[0044] More preferably, diol B in the TPU composition is a homopolymer of butoxy groups. A homopolymer is a polymer composed essentially of only one monomer group, i.e., essentially free of other monomers. "Essentially" means that at least 95 mol% of the homopolymer is composed of butoxy groups, more preferably at least 97.5 mol%, and particularly preferably at least 99 mol%. The molecular weight of diol B is preferably from 500 g / mol to 2.0 x 10 3 In another preferred embodiment, the number average molecular weight of diol B is in the range of 0.6×10 3 g / mol, 0.7 × 10 3g / mol, 0.8 × 10 3 g / mol, 0.9 × 10 3 g / mol, 1.0 × 10 3 g / mol, 1.1 × 10 3 g / mol, 1.1 × 10 3 g / mol, 1.2 × 10 3 g / mol, 1.3 × 10 3 g / mol, 1.4 × 10 3 g / mol, 1.5 × 10 3 g / mol, 1.6 × 10 3 / mol, 1.7 × 10 3 g / mol, 1.8 × 10 3 g / mol, 1.9 × 10 3 g / mol, or 2.0 × 10 3 g / mol.

[0045] In another preferred embodiment, the film according to any of the preceding embodiments, or one of the preferred embodiments thereof, is a block copolymer in which diol A is a block copolymer having a block and two termini, the block comprising ethoxy and propoxy groups, and both termini of the block copolymer comprising exclusively ethoxy groups.

[0046] In this block polymer, the proportion of ethoxy groups at both ends of the block copolymer is preferably more than 5 mol%, more preferably at least 10 mol%, particularly preferably at least 15 mol%, based on the number average molecular weight of the entire block copolymer. The ends of the block copolymer very particularly preferably contain 10 mol% to 20 mol% of ethoxy groups, based on the entire block copolymer, and the blocks of the block copolymer very particularly preferably contain 60 mol% to 70 mol% of ethoxy groups and further 15 mol% to 20 mol% of propoxy groups, based on the entire block copolymer.

[0047] Polyol A is prepared in a first step by adding the desired cyclic alkylene oxide, in this case ethylene oxide and propylene oxide, to a bifunctional starter molecule in a reactor, resulting in ring-opening and polymerization of the cyclic alkylene oxide to form a prepolymer. Preference is given to using a starter molecule having two OH groups, preferably primary OH groups. Very particularly preferred examples are 1,2-ethylene glycol (also known as monoethyl glycol (MEG)), diethylene glycol (DEG), monopropanediol (MPG), preferably 1,3-propylene glycol, and dipropanediol (DPG), preferably 4-oxa-1,7-heptanediol. The structure of the prepolymer can be determined by the addition of the alkylene oxide. When ethylene oxide and then propylene oxide are added alternately, blocks of these monomers are formed in the prepolymer as a function of the addition amount; this is also called the block operation mode. When both alkylene oxides are added simultaneously, the alkylene oxides react optionally, which is also referred to as a mixed mode of operation. The mixed mode of operation is preferred. Those skilled in the art can control the polyol structure and monomer molar distribution within a narrow range based on the control of the molecular weight and addition amount of alkylene oxide. In a preferred embodiment, ethylene oxide is added exclusively to the prepolymer from step 1 in step 2, resulting in diol A having terminal ethoxy groups. In a preferred embodiment, diol A is 1.5×10 3 g / mol to 3.0 × 10 3 In another preferred embodiment, diol A has a number average molecular weight of between 1.6×10 g / mol. 3 g / mol, 1.8 × 10 3 g / mol, 2.0 × 10 3 g / mol, 2.2 × 10 3 g / mol, 2.4 × 10 3 g / mol, 2.6 × 10 3 g / mol, or 2.8 x 10 3 It has a number average molecular weight of g / mol.

[0048] The ring-opening polymerization is carried out with the aid of a catalyst. Here, basic catalysts such as alkali metal or alkaline earth metal hydroxides or alkali metal or alkaline earth metal alkoxides are preferred, preferably NaOH, KOH, CsOH, or sodium methoxide and potassium methoxide. Other preferred catalysts are those containing functional amino groups; preferred examples are N,N-dimethylethanolamine (DMEOA) or imidazole. A third group of preferred catalysts is carbenes, preferably N-heterocyclic carbenes.

[0049] The product obtained in step 2 is precipitated in step 3 by a precipitating agent. The precipitating agent is usually a proton donor. Examples of preferred precipitating agents are carbonic acid (H2CO3) and phosphoric acid (H3PO4). The polymer treated in step 3 is filtered in step 4 to remove the catalyst. A binder is used as a filter aid; preferred examples of the binder (binding agent) are cellulose or silica gel. Polyol B is prepared in a similar manner, where the exclusive butylene oxide used in steps 1 and 2 is omitted.

[0050] A preferred polyol A is a polyol available from BASF Polyurethanes GmbH in October 2013 under the name Lupranol VP9243.

[0051] Chain extender In a preferred embodiment including all the features of the preceding embodiments, or preferred embodiments thereof, a chain extender is included in the thermoplastic polyurethane of the TPU composition, which is preferably aliphatic, araliphatic, aromatic, or cycloaliphatic. The molecular weight is preferably 0.05×10 3 kg / mol~0.499×10 3 The chain extender is preferably a difunctional compound, i.e., one having two groups reactive with isocyanates. The chain extender is preferably a diamine or alkanediol having 2 to 10 carbon atoms in the alkylene group, or a mixture thereof.

[0052] In a preferred embodiment, the chain extender is selected from the group consisting of 1,2-ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, dipropylene glycol, of the aforementioned alkylenes, di-, tri-, tetra-, penta-, hexa-, hepta-, octa-, nona- and / or deca-alkylene glycols, 1,4-cyclohexanediol, 1,4-dimethanolcyclohexane, neopentyl glycol and hydroquinone bis(β-hydroxyethyl) ether (HQEE), or a mixture thereof.

[0053] Preferably, the chain extender is selected from the group consisting of 1,3-propanediol, 1,4-butanediol, and 1,6-hexanediol, or a mixture thereof.

[0054] 1,6-Hexanediol is very particularly preferably used as chain extender.

[0055] Ionic liquid or salt In a preferred embodiment, the salt, ionic liquid or mixture thereof is present in the TPU composition in an amount of 0.1 to 25% by weight, preferably 1 to 10% by weight, more preferably 1.5 to 7.5% by weight, and especially preferably 2 to 5% by weight of the thermoplastic composition, where the weight percentages are based on the total amount of the thermoplastic polyurethane composition into which the salt and / or ionic liquid is incorporated.

[0056] In principle, any salt or any ionic liquid is suitable for incorporation into the thermoplastic polyurethane composition, with salts being preferred in one preferred embodiment and ionic liquids being preferred in yet another preferred embodiment.

[0057] ionic liquids Suitable ionic liquids can be found in WO2011 / 069960, which is incorporated by reference into the present patent application.

[0058] Ionic liquids are either single substances or mixtures of different substances.

[0059] The ionic liquid is preferably liquid at temperatures above 210°C, preferably above 200°C, particularly preferably above 190°C.

[0060] A preferred group of ionic liquids are those containing an imidazole ring, particularly preferred are the 1-butyl-3-methylimidazolium ion (BMIM) or the 1-ethyl-3-methylimidazolium ion (EMIM).

[0061] Another group of preferred ionic liquids comprises diazabicyclo structures, particularly preferred are the monoprotonated forms of 1,8-diazabicyclo[5.4.undec-7-ene (DBU)] or 1,5-diazabicyclo[4.3.non-5-ene].

[0062] salt Preferred salts for use in thermoplastic polyurethane compositions are salts of inorganic or low molecular weight organic protonic acids. Low molecular weight means that the molecular weight of the protonic acid is less than 0.5×10 3 kg / mol, preferably less than 0.4×10 3 g / mol, and particularly preferably less than 0.3 × 10 3 This means that the value is less than g / mol.

[0063] The salt is preferably selected from the group consisting of alkaline earth metal salts, perchlorates or quaternary ammonium salts, or a mixture thereof. Preferably, the salt is selected from the group consisting of LiClO4, LiCF3SO3, NaClO4, LiBF4, NaBF4, KBF4, NaCF3SO3, KClO4, KPF6, KCF3SO3, KC4F9SO3, Ca(ClO4), Ca(PF6), Mg(ClO4), Mg(CF3SO3), Zn(ClO4), Zn(PF6), Ca(CF3SO3), quaternary ammonium ethosulfate, mixtures of fatty acid polyol esters and sodium perchlorate, partial fatty acid esters, alkali metal salts of quaternary ammonium compounds in combination with sodium dicyanamide, the Na salt of dodecylbenzenesulfonic acid and 1-hydroxy-tallow-1-trimethylammonium chloride, or a mixture thereof. Preference is given to salts selected from the group consisting of LiClO4, LiCF3SO3, NaClO4, LiBF4 or mixtures thereof, very particularly preferred is LiCF3SO3.

[0064] In one preferred embodiment, a single salt is used in the thermoplastic polyurethane composition. In a further preferred embodiment, at least two salts are used. In a further preferred embodiment, at least one salt and an ionic liquid are included in the thermoplastic polyurethane composition.

[0065] Polymer 2 is particularly preferably selected from the group consisting of polyethylene, polypropylene and polystyrene. Polymer 2 is preferably polyethylene, more preferably low density polyethylene (LDPE), and even more preferably linear low density polyethylene (LLDPE).

[0066] Preferably, the thermoplastic polyurethane of the TPU composition is present in the film in an amount between 0.01% and 10% by weight, preferably between 0.1% and 5% by weight, more preferably between 0.5% and 3% by weight, and even more preferably between 0.5% and 3% by weight, based on the total weight of the film.

[0067] catalyst The catalyst (d) particularly promotes the reaction between the NCO groups of the diisocyanate (a) and the isocyanate-reactive hydroxyl groups of the compound (also called polyol) and the chain extender (c), and in a preferred embodiment is a tertiary amine, in particular triethylamine, dimethylcyclohexylamine, N-methylmorpholine, N,N'-dimethyl-piperazine, 2-(dimethylaminoethoxy)ethanol, or diazabicyclo[2.2 octane]. In another preferred embodiment, the catalyst is selected from the group consisting of organometallic compounds, preferably titanate esters, iron compounds, tin compounds, or bismuth salts. A preferred iron compound is iron(III) acetylacetonate. A preferred tin compound is tin diacetate, tin dioctate, tin dilaurate, or a dialkyltin salt of an aliphatic carboxylic acid, preferably tin dioctate, tetrabutyl ester, or orthotitanate. In preferred bismuth salts, bismuth is present in oxidation state 2 or 3, especially 3, and are preferably salts of carboxylic acids, the carboxylic acids preferably having 6 to 14 carbon atoms, especially preferably 8 to 12 carbon atoms. Highly preferred bismuth salts are bismuth(III) neodecanoate, bismuth 2-ethylhexanoate or bismuth octanoate, or mixtures thereof.

[0068] Preference is given to using tin catalysts, especially tin dioctoate.

[0069] The catalyst (d) is preferably used in an amount of 0.0001 to 0.1 part by mass per 100 parts by mass of the compound reactive with isocyanate, also known as polyol, and the chain extender.

[0070] Auxiliaries / Additives In addition to the catalyst, auxiliary and / or additive agents can also be added to the composition. Examples include surfactants, fillers, flame retardants, nucleating agents, oxidation stabilizers, lubricants and mold release agents, dyes and pigments, and optionally stabilizers, such as stabilizers against hydrolysis, light, heat, or discoloration, inorganic and / or organic fillers, reinforcing agents, and plasticizers. Oligomeric and / or polymeric aliphatic or aromatic carbodiimides are preferably used as hydrolysis inhibitors. To stabilize the TPU of the present invention against aging, stabilizers are preferably added to the TPU. For the purposes of this invention, stabilizers are additives that protect plastics or plastic mixtures from harmful environmental influences. Examples are primary and secondary antioxidants, hindered amine light stabilizers, UV absorbers, hydrolysis inhibitors, quenchers, and flame retardants. Examples of commercially available stabilizers can be found in Plastics Additive Handbook, 5th Edition, edited by H. Zweifel, Hanser Publishers, Munich, 2001 ([), pp. 98-136).

[0071] In a preferred embodiment, the UV absorber is 0.3×10 3 Number average molecular weights exceeding 0.39 × 10 g / mol, especially 3 Furthermore, the UV absorbers preferably used have a number average molecular weight of more than 5×10 g / mol. 3 Molecular weight not exceeding 2×10 g / mol, particularly preferably 2×10 3 It should have a molecular weight not exceeding g / mol.

[0072] Particularly suitable UV absorbers are benzotriazoles. Examples of particularly suitable benzotriazoles are Tinuvin® 213, Tinuvin® 234, Tinuvin® 571 and Tinuvin® 384, as well as Eversorb® 82. The UV absorbers are usually added in an amount of 0.01 to 5% by weight, preferably 0.1 to 2.0% by weight, in particular 0.2 to 0.5% by weight, based on the total weight of the TPU.

[0073] The above-mentioned UV stabilization based on antioxidants and UV absorbers is often still not sufficient to ensure good stability of the film against the harmful effects of UV rays. In this case, hindered amine light stabilizers (HALS) can be added to the film in addition to antioxidants and UV absorbers. HALS are very efficient UV stabilizers for most polymers.

[0074] HALS compounds are generally known and commercially available. Examples of commercially available HALS can be found in Plastics Additive Handbook, 5th Edition, H. Zweifel, Hanser Publishers, Munich, 2001, pp. 123-136.

[0075] It is preferred to use a hindered amine light stabilizer having a number average molecular weight of more than 500 g / mol.Furthermore, the molecular weight of the preferred HALS compounds should not exceed 10,000 g / mol, particularly preferably not exceed 5,000 g / mol.

[0076] Particularly preferred hindered amine light stabilizers are bis(1,2,2,6,6-pentamethylpiperidyl) sebacate (Tinuvin® 765, Ciba Spezialitaetenchemie AG) and the condensation product of 1-hydroxyethyl-2,2,6,6-tetramethyl-4-hydroxypiperidine with succinic acid (Tinuvin® 622). The condensation product of 1-hydroxyethyl-2,2,6,6-tetramethyl-4-hydroxypiperidine with succinic acid (Tinuvin® 622) is particularly preferred when the titanium content of the product is <150 ppm, preferably <50 ppm, and especially <10 ppm. The HALS compound is preferably used in a concentration of 0.01 to 5% by weight, particularly preferably 0.1 to 1% by weight, and especially 0.15 to 0.3% by weight, based on the total weight of the film.

[0077] A particularly preferred UV stabilizing system comprises a mixture of a phenolic stabilizer, a benzotriazole, and a HALS compound in the preferred amounts described above.

[0078] In one preferred embodiment of the film, a hydrolysis inhibitor is included as an adjuvant in the TPU composition, where oligomeric and / or polymeric aliphatic or aromatic carbodiimides are preferred.

[0079] Further details regarding the abovementioned auxiliaries and additives can be found in the specialist literature, for example in Plastics Additive Handbook, 5th edition, edited by H. Zweifel, Hanser Publishers, Munich, 2001.

[0080] Preparation of TPU composition Thermoplastic polyurethanes are prepared by known methods, batchwise or continuously, preferably by the one-shot or prepolymer method, using a reactive extruder or belt process. In this process, the components to be reacted, i.e., isocyanate, polyol, and optionally chain extender and / or catalyst and / or additive and / or auxiliary, can be mixed together successively (one after the other) or simultaneously, and the reaction begins immediately. In the extrusion process, the components, i.e., isocyanate, polyol, and optionally chain extender and / or additive and / or auxiliary, are introduced individually or as a mixture into an extruder and reacted at a temperature of preferably 100°C to 280°C, more preferably 140°C to 250°C, and the resulting polyurethane is extruded, cooled, and pelletized.

[0081] Twin screw extruders are preferred because they operate with positive conveying and therefore allow for more precise setting of temperatures and output rates on the extruder.

[0082] Thermoplastic polyurethanes having a Shore A hardness of less than 95 are preferred, more preferably between 95 Shore A and 75 Shore A, and even more preferably between 95 Shore A and 80 Shore A. Certain preferred thermoplastic polyurethane compositions include a thermoplastic polyurethane having a Shore A hardness of about 85 Shore A. Polyol and chain extender can advantageously be used in a molar ratio of 1:1 to 1:15, preferably 1:2.5 to 1:10. These soft thermoplastic polyurethanes are suitable for use in stretched films. To prepare harder TPUs having hardnesses greater than 98 Shore A, preferably between 55 Shore D and 75 Shore D, the molar ratio of polyol to chain extender is in the range of 1:10 to 1:20, preferably 1:12 to 1:15.

[0083] To prepare the thermoplastic polyurethane, the forming components diisocyanate and polyol and, optionally, catalyst are reacted, optionally in the presence of auxiliaries and / or additives, in amounts such that the equivalent ratio of NCO groups of diisocyanate (a) to the sum of hydroxyl groups of the polyol and chain extender is 0.95 to 1.10:1, preferably 0.98 to 1.08:1, and in particular about 1.0 to 1.05:1.

[0084] The TPU composition is produced by preparing a thermoplastic polyurethane as described above in step 1 and mixing this thermoplastic polyurethane with a salt or an ionic liquid, preferably an ionic liquid, in step 2. In a preferred embodiment, additives and / or auxiliaries are added in step 1, step 2 and / or a separate step 3. These steps may be performed together or one after the other regardless of the numbers given to the steps. Preferably, step 2 follows step 1.

[0085] Preferably, Layer B is made by preparing the thermoplastic polyurethane composition described above. In a preferred embodiment comprising a Polymer 2 composition in Layer B, the TPU composition is mixed with the Polymer 2 composition in Step 4. The resulting product, also referred to as a blend, comprises the thermoplastic polyurethane composition as a network in the Polymer 2 composition.

[0086] adhesive layer A film according to any of the present embodiments, or preferred embodiments thereof, having at least two layers, Layer A and Layer B, each layer having an inner surface in contact with the respective other layer and an outer surface opposite the inner surface, preferably further comprises an adhesive on one of its outer surfaces, with the adhesive (pressure-sensitive adhesive) preferably being on the outer surface of Layer 1.

[0087] The adhesive used in the film can be any adhesive compatible with the Polymer 1 composition, the thermoplastic polyurethane composition, or the Polymer 2 composition. The adhesive is Layer C, which can be in the form of spots, any kind of net structure, regular or irregular, or a film.

[0088] The adhesive may be a non-reactive adhesive or a reactive adhesive, with a non-reactive adhesive being preferred.

[0089] Preferred examples of non-reactive adhesives are selected from the group consisting of polymer dispersion adhesives, preferably based on polyvinyl acetate (PVAc), pressure sensitive adhesives (PSA), preferably based on acrylate polymers, contact adhesives, preferably based on natural rubber or polychloroprene, hot melt adhesives, preferably based on ethylene-vinyl acetate or polyethylene (PE), multi-component adhesives, preferably those linked to acrylic, urethane or epoxy, and one-part adhesives.

[0090] Preferred combinations of multi-component adhesives are polyester-polyurethane resin, polyol-polyurethane resin, and acrylic polymer-polyurethane resin. Multi-component resins may be either solvent-based or solventless.

[0091] One-part adhesives cure via chemical reaction with an external energy source such as radiation, heat, and moisture. Ultraviolet (UV) light-curable adhesives, also known as light-curable materials (LCMs), are preferably acrylic-based. Heat-curable adhesives consist of a pre-formed mixture of two or more components. When heat is applied, the components react and crosslink. These adhesives preferably include thermosetting epoxies, urethanes, and polyimides. Moisture-curable adhesives cure upon reaction with moisture present on the substrate surface or in the air. These adhesives include cyanoacrylates and urethanes.

[0092] Preferably the adhesive is a thermoplastic or thermosetting material, preferably a thermoplastic, more preferably a polyethylene.

[0093] ULDPE: In a preferred embodiment including all of the features of the preceding embodiment or one of the preferred embodiments thereof, the adhesive comprises ultra-low density polyethylene (ULDPE). Preferably, the adhesive is ultra-low density polyethylene (ULDPE).

[0094] Preferably, the ultra-low density polyethylene (ULDPE) has a density of 0.85 g / cm, measured according to DIN EN ISO 1183-1:2019, A. 3 and 0.95 g / cm 3 and more preferably 0.89 g / cm 3 and 0.91 g / cm 3 and most preferably 0.90 g / cm 3 is.

[0095] The melt flow index (MFI, also referred to as melt flow rate MFR) of the ultra low density polyethylene (ULDPE) is preferably between 1.0 g / 10 min and 5.0 g / 10 min, more preferably between 2.0 g / 10 min and 4.0 g / 10 min, even more preferably between 2.5 g / 10 min and 3.5 g / 10 min, and most preferably 3.0 g / 10 min, at 190°C and a load of 2.16 kg, measured according to DIN EN ISO 1133-1:2011.

[0096] The Vicat temperature of the ultra low density polyethylene (ULDPE) is preferably between 85°C and 95°C, more preferably between 87°C and 93°C, even more preferably between 88°C and 92°C, even more preferably between 89°C and 91°C, and most preferably 90°C, measured according to DIN EN ISO 306:2013, A.

[0097] In preferred embodiments of the ULDPE, the parameters of density, melt flow index, and Vicat temperature are a single preferred parameter, or in other preferred embodiments, two of these preferred parameters appear together in the ULDPE, or three of these preferred parameters appear together.

[0098] In another preferred embodiment, the film according to any of the above-mentioned embodiments or one of the preferred embodiments thereof has a film thickness of 10 12 It has an electrical resistance of less than an ohm.

[0099] In another preferred embodiment, a film according to any of the above-mentioned embodiments, or one of the preferred embodiments thereof, Layer B comprises a Polymer 2 composition comprising a thermoplastic polyurethane composition, as outlined above.

[0100] In another preferred embodiment, in a film according to any of the above-described embodiments, or one of the preferred embodiments thereof, the Polymer 2 composition comprises LDPE as the only polymer. In another preferred embodiment, the Polymer 2 composition is LDPE.

[0101] Use of thermoplastic polyurethane composition in film Another aspect of the present invention is a method of using a thermoplastic polyurethane composition in a film, preferably a stretch film according to any of the above-described embodiments or preferred embodiments thereof, comprising the steps of: Here, in a first embodiment, the film comprises at least two layers, Layer A and Layer B, each layer having an inner surface in contact with the respective other layer, and an outer surface opposite the inner surface, wherein: Layer A comprises a Polymer 1 composition, preferably a Polymer 1 composition, layer B comprises a thermoplastic polyurethane composition (TPU composition) and optionally a polymer 2 composition, preferably consisting of a TPU composition or a TPU composition and a polymer 2 composition, The polyurethane of said TPU composition is preferably ○Organic diisocyanates, a polyol comprising a diol A and a diol B, wherein the diol A comprises ethoxy and propoxy groups and the diol B comprises butoxy groups; chain extenders, prepared from, and The TPU composition includes a salt and / or an ionic liquid.

[0102] Film manufacturing Another aspect of the present invention is a method for producing a film according to the above-described embodiment, or a film according to a preferred embodiment thereof, comprising at least three steps: Step 1: producing the layer A described above; Step 2: producing the layer B described above; Step 3: combining at least Layer A and Layer B to form a film; Finally, step 4: adding adhesive to the outside of at least one of layer A or layer B; The method includes:

[0103] In one preferred embodiment, steps 1 and 2 are carried out independently, followed by steps 3 and 4. In another preferred embodiment, steps 1, 2 and 3, and more preferably also step 4, are carried out simultaneously. In a highly preferred embodiment, the process is carried out by a multilayer blown film extrusion process.

[0104] Use of film In a preferred embodiment, a film of the above-described embodiment, or according to a preferred embodiment thereof, is used to package materials or devices that are adversely affected by electrostatic charging or that are used in environments where electrostatic charging must be avoided.

[0105] In the above, the word "comprises" used in the preferred embodiment may be read as "is", which is a preferred embodiment of the embodiment using "comprises". [Example]

[0106] Example (EEE) Example 1 - Materials Used LLDPE: 0.92 g cm -3 (measured according to DIN EN ISO 1183-1:2019, A), an MFR (measured according to DIN EN ISO 1133-1:2011) of 1.0 g / (10 min) at 190°C and 2.16 kg, and a Vicat temperature (measured according to DIN EN ISO 306:2013, A) of 102°C.

[0107] ULDPE: 0.90 g cm -3(measured according to DIN EN ISO 1183-1:2019, A), an MFR at 190°C and 2.16 kg of 3.0 g / (10 min) (measured according to DIN EN ISO 1133-1:2011), and a Vicat temperature of 90°C (measured according to DIN EN ISO 306:2013, A).

[0108] LDPE: 0.92 g cm -3 (measured according to DIN EN ISO 1183-1:2019, A), an MFR of 1.0 g / (10 min) at 190°C and 2.16 kg (measured according to DIN EN ISO 1133-1:2011), and a Vicat temperature of 96°C (measured according to DIN EN ISO 306:2013, A).

[0109] Additive: a polyol mixture containing a thermoplastic polyurethane based on HDI, polytetramethylene glycol (PTMG) with a molecular weight in the range of 500 g / mol to 2000 g / mol, a polyol with a molecular weight in the range of 1500 g / mol to 3000 g / mol and containing ethoxy and propoxy groups, and 1,6-hexane-diol, with about 3% by weight of 1-ethyl-3-methylimidazolium ion (EMIM).

[0110] Example 2 - Preparation of a two-layer film with ULDPE and LLDPE (Comparative) To produce the bilayer film, the required polymers, ULDPE (Layer C in Table 1) and LLDPE (Layer A in Table 1), were fed into separate single-screw extruders and melted at temperatures between 180 and 210°C. The melts were then separately dispensed into two concentric nozzles, and air was blown into them to maintain the tubular shape. These were then laminated together to form a tubular film with an inner layer of approximately 0.003 mm of ULDPE (Layer C) and an outer layer of approximately 0.017 mm of LLDPE (Layer A). The tubular film was then cut along its axis to form films, which were then stored for 3 days before being used for the following measurements.

[0111] Example 3 - 3-layer film To produce the antistatic three-layer film, in a first step, 85% by weight of LDPE and 15% by weight of additives were mixed in a twin-screw extruder at a temperature ranging from 180°C to 200°C to obtain the blend that was further used.

[0112] In the second step, ULDPE (Layer C in Table 1), LLDPE (Layer A in Table 1), and the blend produced in the first step (Layer B in Table 1) were fed into separate melting devices, such as a single-screw extruder, and melted at temperatures between 180°C and 210°C. The melts of each of the three layers were separately dispensed into concentric ring nozzles. Air was then blown through these concentric nozzles to maintain the tubular shape, and the layers were laminated together to form a tubular film with an inner ULDPE layer (Layer C) of approximately 0.003 mm, a central LLDPE layer (Layer A) of approximately 0.017 mm, and an outer blend layer (Layer B) of approximately 0.003 mm. This tubular film was cut along its axis to form films, which were then stored for 3 days and then used for the following measurements.

[0113] Example 4 - Measurements The surface resistivity of the antistatic stretched films according to Examples 2 and 3 was measured in the unstretched state (at 0% elongation) and in the stretched state (at 200% elongation) in accordance with DIN 62631-3-2:2018-09.

[0114] [Table 1]

Claims

1. A stretchable film comprising at least two layers, Layer A and Layer B, each layer having an inner surface in contact with the other layer and an outer surface opposite the inner surface; Layer A comprises the Polymer 1 composition; Layer B comprises a thermoplastic polyurethane composition, and optionally a Polymer 2 composition; The polyurethane in the thermoplastic polyurethane composition is ○Organic diisocyanates, a polyol comprising a diol A and a diol B, wherein the diol A comprises ethoxy and propoxy groups and the diol B comprises butoxy groups; chain extenders, and The thermoplastic polyurethane composition comprises a salt, an ionic liquid, or a salt and an ionic liquid, and the film has an elongation at break of more than 50%, measured according to DIN ISO 53504, 2017-03, and an electrical resistivity of less than 10 Ω, measured according to DIN EN 62631-3-2:2018-09.

2. 2. The film of claim 1, wherein the elongation at break, measured in accordance with DIN ISO 53504, 2017-03, is greater than 100%.

3. A film as described in claim 1, characterized in that the elongation at break is greater than 150%, measured in accordance with DIN ISO 53504, 2017-03.

4. A film as described in claim 1, characterized in that the elongation at break is greater than 200%, measured in accordance with DIN ISO 53504, 2017-03.

5. A film as described in claim 1, characterized in that the elongation at break is greater than 250%, measured in accordance with DIN ISO 53504, 2017-03.

6. A film as described in claim 1, characterized in that the elongation at break is greater than 300%, measured in accordance with DIN ISO 53504, 2017-03.

7. 7. The film according to claim 1, wherein the polymer of the polymer 1 composition is selected from polystyrene (PS), polyoxymethylene (POM), ethylene vinyl acetate (EVA), acrylonitrile-butadiene-styrene (ABS), thermoplastic polyurethane (TPU), polyvinyl chloride (PVC), polyethylene (PE), and polypropylene (PP), or a mixture thereof.

8. 8. The film according to claim 1, wherein the polymer 1 is a low density polyethylene (LDPE) or a linear low density polyethylene (LLDPE), or a mixture thereof.

9. The film of claim 8, wherein polymer 1 is a mixture of low density polyethylene (LDPE) and linear low density polyethylene (LLDPE).

10. 10. The film of any one of claims 1 to 9, further comprising an adhesive on one of its outer surfaces.

11. A film as described in claim 10, characterized in that the adhesive is on the outer surface of polymer 1.

12. 12. The film of claim 10 or 11, wherein the adhesive comprises ultra-low density polyethylene (ULDPE).

13. The film according to any one of claims 1 to 12, wherein Layer B comprises Polymer 2 comprising a thermoplastic polyurethane composition different from the thermoplastic polyurethane composition comprising a salt, an ionic liquid, or a salt and an ionic liquid.

14. The film according to any one of claims 1 to 13, wherein the diol A is a block copolymer having a block and two terminal ends, and the block contains an ethoxy group and a propoxy group, and the two terminal ends of the block copolymer are ethoxy groups.

15. The film according to any one of claims 1 to 14, wherein the ionic liquid contains an imidazole ring.

16. At least three steps: Step 1: Producing Layer A; Step 2: Producing Layer B; Step 3: combining at least Layer A and Layer B to form a film; Finally, step 4: adding layer C containing adhesive to the outside of at least one of layer A or layer B; 16. A method for producing a film according to any one of claims 1 to 15, comprising:

17. A method for producing a film according to claim 16, further comprising step 4 of applying to the outside of layer A a layer C comprising an adhesive.

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