3D network structure with high resilience, soft touch feeling and good quietness and method of preparing the same

Abstract

The present invention relates to a 3D network structure comprising a thermoplastic polyurethane, wherein the thermoplastic polyurethane has a hardphase ratio ranging from 10wt% to 40wt% and wherein the thermoplastic polyurethane has a processing temperature window at which the thermoplastic polyurethane has a viscosity ranging from 103 Pa·s to 105 Pa·s. The present invention also relates to an article comprising the 3D network structure.

Description

[0001] 3D NETWORK STRUCTURE WITH HIGH RESILIENCE, SOFT TOUCH FEELING AND GOOD QUIETNESS AND METHOD OF PREPARING THE SAME

[0002] FIELD OF THE PRESENT INVENTION

[0003] The present invention relates to a three-dimensional (3D) network structure comprising a thermoplastic polyurethane, and a method of preparing the 3D network structure.

[0004] BACKGROUND OF THE PRESENT INVENTION

[0005] Three-dimensional (3D) mesh has a 3D network structure and is widely applied for example in the mattress and chair cushion. Currently, 3D mesh is mainly made of polyethylene (PE), polyolefin elastomer (POE) or thermoplastic polyether ester elastomer (TPEE). However, such 3D mesh has poor touch feeling and quietness.

[0006] Thermoplastic polyurethane (TPU) is a class of elastomer having excellent properties such as high strength, high toughness, wear resistance, oil resistance, anti-bacterial property, and good processing performance, and is widely used in many fields such as sports, medical and food. However, only few patents disclose the application of TPU in the 3D mesh.

[0007] US2015 / 0087196A1 discloses an elastic network structure including a three-dimensional random loop bonded structure made of a continuous linear structure. This patent generally mentions that the thermoplastic resin for forming the network structure is at least one thermoplastic resin selected from the group consisting of a soft polyolefin, a polystyrene thermoplastic elastomer, a polyester thermoplastic elastomer, a polyurethane thermoplastic elastomer and a polyamide thermoplastic elastomer, and gives some specific examples for preparing the network structure by using the polyester thermoplastic elastomer. However, this document does not provide any example for preparing the network structure by using a polyurethane thermoplastic elastomer.

[0008] US2016 / 0237603A1 discloses a network structure made of a three-dimensional random loop bonded structure obtained by forming random loops with curling treatment of a continuous linear structure including at least one thermoplastic elastic resin selected from the group consisting of a polyolefin-based thermoplastic elastomer, an ethylene-vinyl acetate copolymer, a polyurethane-based thermoplastic elastomer and a polyamide-based thermoplastic elastomer. This document measures repeated compression durability and repulsion characteristics of the obtained cushion. However, this document does not mention the touch feeling and quietness of the cushion.

[0009] Since high resilience, soft touch feeling and good quietness are important for the application of the 3D network structure, there is still a need to provide a 3D network structure having high resilience, soft touch feeling and good quietness. SUMMARY OF THE PRESENT INVENTION

[0010] The object of the present invention is to provide a 3D network structure having high resilience, soft touch feeling and good quietness.

[0011] Accordingly, the present invention provides a 3D network structure comprising a thermoplastic polyurethane, wherein the thermoplastic polyurethane has a hardphase ratio ranging from 10wt% to 40wt% and wherein the thermoplastic polyurethane has a processing temperature window at which the thermoplastic polyurethane has a viscosity ranging from 103Pa s to 105Pa s.

[0012] The present invention also provides an article comprising the 3D network structure.

[0013] It has been found that the 3D network structure of the present invention shows high resilience, soft touch feeling and good quietness.

[0014] DESCRIPTION OF DRAWING

[0015] Figure 1 indicates the compression force response of different 3D mesh samples measured by Dynamic mechanical analysis.

[0016] DETAILED DESCRIPTION OF THE PRESENT INVENTION

[0017] The present invention will be described in detail hereinafter. It is to be understood that the present invention can be embodied in many different ways and shall not be construed as limited to the embodiments set forth herein.

[0018] Unless defined otherwise, all technical and scientific terms used herein have the meaning commonly understood by a person skilled in the art to which the invention belongs. As used herein, the following terms have the meanings ascribed to them below, unless specified otherwise.

[0019] As used herein, the articles “a” and “an” refer to one or to more than one (i.e. , to at least one) of the grammatical object of the article or component.

[0020] As used herein, the terms “comprise”, “comprising”, etc. are used interchangeably with “contain”, “containing”, etc. and are to be interpreted in a non-limiting, open manner. That is, e.g., further components or elements can be present. The expressions “consists of” or “consists essentially of” or cognates can be embraced within “comprises” or cognates.

[0021] Unless otherwise identified, all percentages (%) are “percent by weight”.

[0022] Unless otherwise identified, the molecular weight of each component or polymer means a number average molecular weight (Mn). In the present invention, the molecular weights of each component or polymer were determined using gel permeation chromatography (GPC) according to GB / T 21863-2008.

[0023] In the present invention, the OH values of each polyol were determined according to DIN 53240.

[0024] In the present invention, the hardphase ratio (wt%) of TPU is calculated according to the following formula: fl chain extender X ( M chain extender + M isocyanate ) Hardphase ratio = -

[0025] Total mass nChain extender represents the moles of the chain extender;

[0026] M chain extender represents the molecular weight of the chain extender;

[0027] Misocyanate represents the molecular weight of the isocyanate; and

[0028] Total mass represents the mass sum of the chain extender, the isocyanate and the polyol reacted during the polymerization.

[0029] The processing temperature window is defined by a temperature range of TPU at which TPU has a viscosity range from 103Pa s to 105Pa s, wherein the viscosity of the TPU is measured by a capillary flow tester (CFT-500D from Shimazu) according to JIS K 7311 and JIS K 7210, based on a weight loading of 30 kg.

[0030] In the present invention, the functionality (Fn) of a polyol means the number of terminal hydroxyl groups per polyol molecule. The functionality is determined by the following formula:

[0031] Fn = Mn*(GHv) / 56100 wherein Mnrepresents the number-average molecular weight of the polyol and OHv represents OH value of the polyol.

[0032] In the present invention, the industrial standard fatigue test is carried out according to DIN EN ISO 2439, B.

[0033] In the present invention, the hysteresis loss is measured according to DIN EN ISO 2439, B.

[0034] In the present invention, the compression set is measured according to ISO 1856:2018- Method A, 70°C.

[0035] In the present invention, the noise level is measured using SW6004 Digital Sound Level Meter available from Dongguan Wanchuang Electronic Products Co., Ltd. by placing the meter 5mm away from the 3D mesh sample and pressing the 3D mesh sample repetitively for 20 times and recording the maximum noise level and then calculating an average value of three measurements to obtain the noise level. The lower noise level represents better quietness.

[0036] In the present invention, the ratio of the stress of 3D mesh sample at 40% of compression to the stress of 3D mesh sample at 10% of compression is defined as comfort factor which indicates the comfort level of the 3D mesh sample, wherein higher comfort factor represents better comfort level of the 3D mesh sample.

[0037] In the present invention, the soft touch feeling is measured by 10 people (5 women and 5 men, age ranging from 20 to 50) with hand, which is classified to a rating ranging from 1 to 5 and 5 represents the highest (best) soft touch feeling and 1 represents the lowest soft touch feeling.

[0038] Polyols (a)

[0039] In the present invention, the components for forming the thermoplastic polyurethane can comprise a polyol. The polyol can have a number average molecular weight (Mn) ranging from 500 to 5000, preferably from 700 to 4000, more preferably from 800 to 3000, most preferably from 900 to 1200, such as 600, 900, 1000, 1100, 1200, 1300, 1400, 1500, 2000, 2500, 3000, 3500, 4000, 4500, 5000, etc.

[0040] The polyol can be a polyol conventionally used in the thermoplastic polyurethane, such as a polyether polyol, a polyester polyol such as polycaprolactone polyol, polycarbonate polyol, and a combination thereof, preferably a polyether polyol. Preferably, the polyol can be polyether diol, a polyester diol, polycarbonate diol, and a combination thereof.

[0041] The polyol in the present invention can be produced by known processes in the art or can be commercially available.

[0042] In an embodiment, the polyol can be selected from polyether polyols derived from oxygencontaining heterocyclic compounds comprising 2 to 6 carbon atoms, such as 3, 4, 5 or 6 carbon atoms, preferably tetrahydrofuran. Preferably, the polyol is produced by polymerizing tetrahydrofuran as repeating unit, preferably capped with primary hydroxyl groups. In one preferred embodiment, the polytetrahydrofuran (PTHF) has a functionality of 2, a number average molecular weight (Mn) of 975 to 1025 g / mol, and a OH value (OHv) of 109.5 to 115.1 mg KOH / g, such as PTHF1000 from BASF.

[0043] In a preferred embodiment, the polyol is selected from a polyether polyol derived from epoxides, preferably ethylene oxide, propylene oxide or a mixture thereof.

[0044] In an embodiment, the polyol can be selected from polyester polyols include those obtained, for example, from dicarboxylic acids having 2 to 12 carbon atoms, preferably 4 to 6 carbon atoms, and polyhydric alcohols. Suitable dicarboxylic acids include, for example, the following compounds: aliphatic dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, and sebacic acid; or aromatic dicarboxylic acids such as phthalic acid, isophthalic acid and terephthalic acid. The dicarboxylic acids can be used alone or as a mixture, for example as a mixture of succinic acid, glutaric acid and adipic acid. For the preparation of the polyester polyols, it is also possible to optionally use the corresponding dicarboxylic acid derivatives, such as carboxylic acid diesters, anhydrides or acid chlorides having 1 to 4 carbon atoms in the alcohol residue instead of dicarboxylic acid. Examples of suitable polyhydric alcohols include diols having 2 to 10 carbon atoms, preferably 2 to 6 carbon atoms, such as ethylene glycol, diethylene glycol, 1 ,4-butanediol, 1 ,5-pentanediol, 1 ,6-hexanediol, 1 ,10-decanediol, 2,2-dimethyl-1,3-propanediol, 1 ,3- propanediol, or dipropylene glycol. Depending on the desired properties, the polyester polyol can be used alone or as a mixture. Preferred polyester polyols include poly (ethylene glycol adipate), poly (1 ,4-butanediol adipate), poly (ethylene glycol / 1 ,4-butanediol adipate), poly (1 ,6-hexanediol / neopentyl glycol adipate), poly (1 ,6-hexanediol / 1 ,4-butanediol adipate) and polycaprolactone, condensation product of w-hydroxy carboxylic acids such as w-hydroxy hexanoic acid or polymerization product of lactones such as optionally substituted cocaprolactone.

[0045] In an embodiment, the polyol can be selected from polycarbonate polyols derived from carbonic acid and diols, especially those diols having 4 to 6 carbon atoms such as 1 ,4- butanediol or 1 ,6-hexanediol.

[0046] The polyol is preferably used in an amount of from 45wt% to 80wt%, such as 45wt%, 50wt%, 55wt%, 60wt%, 65wt%, 70wt%, 75wt%, 80wt%, etc., based on the total weight of the thermoplastic polyurethane.

[0047] In the present invention, the components for forming the thermoplastic polyurethane can comprise an isocyanate. The isocyanate can comprise all isocyanates known for producing polyurethanes. These isocyanates comprise aliphatic, cycloaliphatic, araliphatic and / or aromatic isocyanates, such as tri-, tetra-, penta-, hexa-, hepta- and / or octamethylene diisocyanate, 2-methylpentamethylene 1 ,5-diisocyanate, 2-ethylbutylene 1 ,4-diisocyanate, pentamethylene 1 ,5-diisocyanate, butylene 1 ,4-diisocyanate, 1-isocyanato-3,3,5-trimethyl-5- isocyanatomethylcyclohexane (isophorone diisocyanate, IPDI), 1 ,4- and / or 1 ,3- bis(isocyanatomethyl)cyclohexane (HXDI), cyclohexane 1 ,4-diisocyanate, 1- methylcyclohexane 2,4- and / or 2,6-diisocyanate and / or dicyclohexylmethane 4,4’-, 2,4’- and 2,2’-diisocyanate, diphenylmethane-diisocyanate (MDI) including diphenylmethane 2,2’-, 2,4’- and / or 4,4’-diisocyanate, polymeric MDI, naphthylene 1 ,5-diisocyanate (NDI), tolylene 2,4- and / or 2,6- diisocyanate (TDI), 3,3’-dimethyl diphenyl diisocyanate, 1 ,2-diphenylethane diisocyanate and / or phenylene diisocyanate, or a mixture thereof.

[0048] Preferably, the isocyanate comprises MDI, particularly 4,4’-diphenylmethane diisocyanate. The isocyanate is preferably used in an amount of from 15wt% to 50wt%, such as 15 wt%, 20wt%, 25wt%, 30wt%, 35wt%, 40wt%, 45wt%, 50 wt%, etc., based on the total weight of the thermoplastic polyurethane.

[0049] Chain extenders (c)

[0050] In the present invention, the components for forming the thermoplastic polyurethane can comprise a chain extender.

[0051] Chain extenders that can be used are substances having a molar mass which is preferably smaller than 500 g / mol, particularly preferably in the range from 60 to 400 g / mol, wherein chain extenders have 2 or more (for example 3) hydrogen atoms reactive toward isocyanates. These chain extenders can be used individually or in the form of a mixture. It is preferable to use diols having molecular weights smaller than 500, particularly from 60 to 400, and in particular from 60 to 350. Examples of those that can be used are aliphatic, cycloaliphatic, and / or araliphatic diols having from 2 to 14, preferably from 2 to 10 carbon atoms, e.g., ethylene glycol, 1 ,3-propanediol, 1 ,4-butanediol (1 ,4-BDO), 1 ,6-hexanediol, 1 ,10-decanediol, 1 ,2-, 1 ,3-, and 1 ,4- dihydroxycyclohexane, diethylene glycol, dipropylene glycol, tripropylene glycol, diethanolamine. Preference is given to using ethylene glycol, 1 ,3- propanediol, or 1 ,4-butanediol, especially 1 ,4-butanediol.

[0052] The chain extender is preferably used in an amount of from 1wt% to 11wt%, more preferably from 3 to 8wt%, such as 1 wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10 wt%, 11wt%, etc., based on the total weight of the thermoplastic polyurethane.

[0053] Additives (d)

[0054] In the present invention, the thermoplastic polyurethane can optionally comprise additives.

[0055] Additives that can be used in the present invention comprise chain regulator, lubricant, surfactant, preservative, pigment, colorant, antioxidant, wax, anti-ultraviolet (UV) additive, stabilizer, thickener, wetting agent, filler and reinforcing agent, or a mixture thereof. In preparing the thermoplastic polyurethane, it is preferred to employ one of above additives, or a mixture thereof.

[0056] The additives are generally used in an amount of from 0 to 12wt%, such as from 0.1 to 10wt%, based on the total weight of the thermoplastic polyurethane.

[0057] According to the present invention, chain regulator, lubricant, antioxidant, and anti-ultraviolet additive are preferably used. The amount of each of them is preferably from 0.1 to 5wt%, more 0.1 to 1.5wt%, each based on the total weight of the thermoplastic polyurethane.

[0058] As chain regulator, it includes an alkyl alcohol with one hydroxyl group, for example, the carbon atom number of the alkyl alcohol can be 2-30, preferably 4-26, and more preferably 10-22. Alkyl alcohols with one hydroxyl end group having 10-20 carbon atoms, preferably 14- 18 carbon atoms, particularly 1 -tetradecanol are preferred. The amount of chain regulator, if present, based on the total weight of the thermoplastic polyurethane, is preferably from 0.1 wt% to 5wt%, more preferably from 0.1wt% to 1.0wt%, such as 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.7wt%, 0.8wt%, 0.9wt%, etc.

[0059] As antioxidant, it is possible to use all compounds which are commonly used for preparing polyurethane, such as tea polyphenols (TP), tocopherols, flavonoids, butylhydroxyanisole (BHA), dibutylhydroxytoluene (BHT), tert-butylhydroquinone (TBHQ), etc. The amount of antioxidant, if present, based on the total weight of the thermoplastic polyurethane, is preferably from 0.1 wt% to 5wt%, more preferably from 0.1 wt% to 1.5wt%, such as 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.7wt%, 0.8wt%, 0.9wt%, 1.0wt%, 1.2wt%, 1.3wt%, 1.4wt%, etc.

[0060] As lubricant, it is possible to use all compounds which are commonly used for preparing polyurethane. The amount of lubricant, if present, based on the total weight of the thermoplastic polyurethane, is preferably from 0.1 wt% to 5wt%, more preferably from 0.1 wt% to 1.0wt%, such as 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.7wt%, 0.8wt%, 0.9wt%, etc.

[0061] As anti-ultraviolet additive, it is possible to use all compounds which are suitable for preparing polyurethane, such as salicylates, phenyl ketones, benzotriazoles, substituted acrylonitriles, triazines, etc. The amount of anti-ultraviolet additive, if present, based on the total weight of the thermoplastic polyurethane, is preferably from 0.1 wt% to 5wt%, more preferably from 0.1 wt% to 1wt%, such as 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.7wt%, 0.8wt%, 0.9wt%, etc.

[0062] Catalysts (e)

[0063] In the present invention, the components for forming the thermoplastic polyurethane can optionally comprise a catalyst (e).

[0064] As catalysts, it is possible to use all compounds which can accelerate the reaction between isocyanates and polyols. Such compounds are known and are described, for example, in “Kunststoffhandbuch, volume 7, Polyurethane”, Carl Hanser Verlag, 3rd edition 1993, chapter 3.4.1. These catalysts comprise amine-based catalysts and catalysts based on organic metal compounds, or a mixture thereof.

[0065] As amine-based catalysts, it is possible to use, for example, strongly basic amines such as N,N,N-triethylaminoethoxyethanol, bis(N,N-dimethylaminoethyl)ether, dimethyl cyclohexylamine, trimethyl hydroxyethyl ethylenediamine, dimethylbenzylamine, triethylamine, triethylenediamine, pentamethyldipropylenetriamine, dimethylethanolamine, N- methylimidazole, N-ethylimidazole, tetramethylhexamethylenediamine, tris(dimethylaminopropyl)hexahydrotriazine, dimethylaminopropylamine, N-ethylmorpholine, diazabicycloundecene, diazabicyclononene. diazabicyclooctane, preferably triethylenediamine or bis(N,N-dimethylaminoethyl)ether.

[0066] As catalysts based on organic metal compounds, it is possible to use, for example, organic tin compounds such as tin(ll) salts of organic carboxylic acids, e.g., tin(ll) acetate, tin(ll) octoate, tin(ll) ethylhexanoate and tin(ll) laurate, and the dialkyltin(IV) salts of organic carboxylic acids, e.g., dibutyltin diacetate, dibutyltin dilaurate, dibutyltin maleate and dioctyltin diacetate, and also Zn salts or Bi salts, e.g., zinc octoate, bismuth(lll) neodecanoate, bismuth 2-ethylhexanoate and bismuth octanoate, or alkali metal salts of carboxylic acids, e.g., potassium acetate or potassium formate.

[0067] If used, the catalyst is preferably used in an amount of from 0.1 ppm to 500 ppm more preferably from 1 ppm to 100 ppm, based on the total weight of the thermoplastic polyurethane.

[0068] In the present invention, the thermoplastic polyurethane has a hardphase ratio ranging from 10wt% to 40wt%, preferably from 15wt% to 40wt%, more preferably from 20wt% to 40wt%, such as 12wt%, 14wt%, 15wt%, 16wt%, 18wt%, 20wt %, 22wt%, 24wt%, 26wt%, 28wt%, 30wt%, 32wt%, 34wt%, 36wt%, 38wt%, 40wt%, etc.

[0069] In the present invention, the thermoplastic polyurethane has a processing temperature window at which the thermoplastic polyurethane has a viscosity range from 103Pa s to 105Pa s, preferably 5x103Pa s to 5x104Pa s, such as 2000 Pa s, 5000 Pa s, 10000 Pa s, 15000 Pa s, 20000 Pa s, 30000 Pa s, 40000 Pa s, 50000 Pa s, 60000 Pa s, 70000 Pa s, 80000 Pa s, 90000 Pa s, etc.

[0070] In the present invention, the thermoplastic polyurethane has a processing temperature window ranging from 80 °C to 260 °C, preferably from 120 °C to 220 °C, more preferably from 165 °C to 190 °C, such as 80 °C, 100 °C, 120 °C, 125 °C, 130 °C, 135 °C, 140 °C, 145 °C, 150 °C, 155 °C, 160 °C, 165 °C, 170 °C, 175 °C, 180 °C, 185 °C, 190 °C, 195 °C, 200 °C, 205 °C, 210 °C, 215 °C, 220 °C, 230 °C, etc. The thermoplastic polyurethane is processed at a temperature of the processing temperature window, preferably at a temperature closer to the lower limit of the processing temperature window, to form the 3D network structure.

[0071] In the present invention, the thermoplastic polyurethane has a shore hardness ranging from 60A to 95A, such as from 65A to 95A, from 70A to 90A, such as, 60A, 65A, 70A, 75A, 80A, 85A, 90A, 95A, etc.

[0072] The thermoplastic polyurethane is generally prepared by reacting polyols, isocyanates and chain extenders and optionally additives and optionally catalysts by methods in the art. In one embodiment of the present invention, the TPU resin is prepared by mixing polyols, isocyanates and chain extenders together with additives such as chain regulator, antioxidant, lubricant and anti-UV additive. The resulting mixture is pulled onto a conveyor belt and passed to a heating zone with infrared heating elements. After heating, the mixture is chopped / ground into pieces / granulate and optionally melted by extruder for further pelletizing with under-water granulation system. The obtained granulate is optionally further dried through fluidized bed to further build its molecular weight and get rid of the absorbed water. The thermoplastic polyurethane could be prepared by reaction extruder process as well. 3D Network structure

[0073] The 3D network structure is prepared by extrusion of thermoplastic resin through die head containing multiple holes and form random 3D structure. The continuous 3D structure is further stacked and bonded with each other to form a continuous 3D mesh. 3D network structure (3D mesh) can be produced by known processes in the art, such as the method described in TW 201538306A which is incorporated here by reference.

[0074] In a preferred embodiment, the 3D network structure is prepared by the blow process including the following steps:

[0075] (1) melting a TPU resin granulate through a single screw extruder;

[0076] (2) converting the TPU resin melt into multiple melt flows by a die head;

[0077] (3) making the melt flows spiral and stack on a water bath surface placed under the die head, and forming the stacked 3D network structure;

[0078] (4) pulling the stacked 3D network structure into the water bath by two rollers placed at the water surface rolling toward the water bath for cooling, wherein the distance of the two rollers is set to be the target thickness of the 3D network structure; and

[0079] (5) pulling the formed 3D network structure out from the water bath and further drying to obtain a final product.

[0080] A 3D network structure according to the present invention has excellent resilience, soft touch feeling and good quietness. The excellent characteristics have made it possible to provide a network structure suitable for cushioning materials that can be used for beds, office chairs, furniture, sofas, seats for vehicles, floor mats, etc.

[0081] Embodiments

[0082] Various embodiments are listed below. It will be understood that the embodiments listed below can be combined with all aspects and other embodiments in accordance with the scope of the present invention.

[0083] Embodiment 1. A 3D network structure comprising a thermoplastic polyurethane, wherein the thermoplastic polyurethane has a hardphase ratio ranging from 10wt% to 40wt% and wherein the thermoplastic polyurethane has a processing temperature window at which the thermoplastic polyurethane has a viscosity ranging from 103Pa s to 105Pa s.

[0084] Embodiment 2. The 3D network structure according to embodiment 1 , wherein the components for forming the thermoplastic polyurethane comprise

[0085] (a) a polyol;

[0086] (b) an isocyanate; and

[0087] (c) a chain extender, preferably,

[0088] (a) 45wt% to 80wt% of a polyol;

[0089] (b) 15wt% to 50wt% of an isocyanate; and

[0090] (c) 1wt% to 11wt% of a chain extender, wherein the wt% is based on the weight sum of each component.

[0091] Embodiment 3. The 3D network structure according to embodiment 2, wherein the components for forming the thermoplastic polyurethane further comprise (d) an additive.

[0092] Embodiment 4. The 3D network structure according to embodiment 3, wherein the additive comprises a chain regulator, a lubricant, a surfactant, a preservative, a pigment, a colorant, an antioxidant, a wax, an anti-ultraviolet additive, a stabilizer, a thickener, a wetting agent, a filler, a reinforcing agent, or a mixture thereof.

[0093] Embodiment 5. The 3D network structure according to embodiment 4, wherein the additive is selected from the group consisting of a chain regulator, a lubricant, an antioxidant, an antiultraviolet additive, or a mixture thereof.

[0094] Embodiment 6. The 3D network structure according to embodiment 5, wherein the chain regulator is an alkyl monohydric alcohol having carbon atoms of 2-30, preferably 4-26, and more preferably 10-22.

[0095] Embodiment 7. The 3D network structure according to any of embodiments 1 to 6, wherein the thermoplastic polyurethane has a processing temperature window at which the thermoplastic polyurethane has a viscosity ranging from 5x103Pa s to 5x104Pa s.

[0096] Embodiment 8. The 3D network structure according to any of embodiments 1 to 7, wherein the thermoplastic polyurethane has a hardphase ratio ranging from 15wt% to 40wt%, preferably from 20wt% to 40wt%.

[0097] Embodiment 9. The 3D network structure according to any of embodiments 1 to 8, wherein the thermoplastic polyurethane is processed at a temperature ranging from 80 °C to 260 °C, preferably from 120 °C to 220 °C, more preferably from 165 °C to 190 °C to form the 3D network structure.

[0098] Embodiment 10. The 3D network structure according to any of embodiments 1 to 9, wherein the thermoplastic polyurethane has a shore hardness ranging from 60A to 95A, preferably from 65A to 95A, more preferably from 70A to 90A.

[0099] Embodiment 11. The 3D network structure according to any of embodiments 2 to 10, wherein the polyol has a number average molecular weight (Mn) ranging from 500 to 5000, preferably from 700 to 4000, more preferably from 800 to 3000, most preferably from 900 to 1200.

[0100] Embodiment 12. The 3D network structure according to any of embodiments 2 to 11, wherein the polyol is selected from a polyether polyol and a polyester polyol, preferably the polyol is selected from polyether polyol derived from oxygen-containing heterocyclic compounds comprising 2 to 6 carbon atoms, preferably tetrahydrofuran, or is selected from polyether polyol derived from epoxides, preferably ethylene oxide, propylene oxide or a mixture thereof. Embodiment 13. The 3D network structure according to any of embodiments 2 to 12, wherein the polyol has a functionality in the range of from 1.5 to 2.5, preferably a functionality in the range of from 1.8 to 2.1.

[0101] Embodiment 14. The 3D network structure according to any of embodiments 2 to 13, wherein the isocyanate comprises aromatic diisocyanate, preferably diphenylmethane diisocyanate.

[0102] Embodiment 15. The 3D network structure according to any of embodiments 1 to 14, wherein the 3D network structure is a 3D mesh.

[0103] Embodiment 16. An article comprising a 3D network structure as defined in any of embodiments 1 to 15.

[0104] EXAMPLES

[0105] The present invention will now be described with reference to Examples and Comparative Examples, which are not intended to limit the present invention.

[0106] Raw materials

[0107] PTHF1000 is a poly tetrahydrofuran from BASF.

[0108] MDI (4,4'-diphenylmethane diisocyanate) is an isocyanate from BASF.

[0109] 1,4-butanediol (1,4-BDO) is a chain extender.

[0110] 1 -tetradecanol is from Sasol.

[0111] Polyolefin elastomer (POE) is TAFMER DF940 from Mitsui chemical.

[0112] Preparation of TPU

[0113] TPUs were prepared according to the general method including the following steps:

[0114] (1) Optionally mixing an additive (chain regulator) together with polyol and dissolving the additive in polyol;

[0115] (2) Pre-heating the mixed polyol and chain extender to 80°C and isocyanate to 50°C separately;

[0116] (3) Mixing the pre-heated polyol, chain extender and isocyanate together under vigorous stirring in a container;

[0117] (4) When the temperature of the mixture reached 110°C, pouring out the mixture from the container to a hot plate set to 135°C for 10 min until the mixture was solidified into a TPU plate;

[0118] (5) Moving the obtained TPU plate into an oven set to 80°C and annealing for 12 hours; and

[0119] (6) Grinding the TPU plate after annealing into granulates for further processing to produce 3D mesh. TPLI-A, TPLI-B, TPLI-C and TPLI-D were prepared by the general method above according to the components and amounts as shown in Table 1 below. Samples made from TPLI-A, TPU- B and TPLI-C are examples according to the present invention and Samples made from TPLI-D are comparative examples.

[0120] Table 1

[0121] The properties of the resulted TPUs are shown in Table 2 below.

[0122] Table 2

[0123] Table 2 shows that TPLI-A, TPLI-B and TPLI-C have a lower processing temperature window relative to TPLI-D. Particularly, TPLI-C shows the lowest processing temperature window.

[0124] Example 1 - preparation of 3D mesh samples

[0125] The 3D mesh samples were prepared by the general blow process including the following steps:

[0126] (1) melting a TPU granulate through a single screw extruder at a certain temperature;

[0127] (2) converting the TPU melt into multiple melt flows by a die head;

[0128] (3) making the melt flows spiral and stack on a water bath surface placed under the die head, and forming the stacked 3D mesh sample, wherein said water bath has a temperature of 10°C;

[0129] (4) pulling the stacked 3D mesh sample into the water bath by two rollers placed at the water surface rolling toward the water bath for cooling, wherein the distance of the two rollers is set to be the target thickness of the 3D mesh sample, wherein the linear speed of the two rollers is 1m / min and the distance of the two rollers is 5cm; and

[0130] (5) pulling the formed 3D mesh sample out from the water bath and further drying at room temperature (RT) to obtain a final product.

[0131] 3D mesh sample A

[0132] 3D mesh sample A was prepared by the above general blow process wherein TPU-A granulate was melted through a single screw extruder at a temperature of 180°C in step (1). 3D mesh sample B-1

[0133] 3D mesh sample B-1 was prepared by the above general blow process wherein TPLI-B granulate was melted through a single screw extruder at a temperature of 190°C in step (1).

[0134] 3D mesh sample B-2

[0135] 3D mesh sample B-2 was prepared by the above general blow process wherein TPLI-B granulate was melted through a single screw extruder at a temperature of 180°C in step (1).

[0136] 3D mesh sample C-1

[0137] 3D mesh sample C-1 was prepared by the above general blow process wherein TPLI-C granulate was melted through a single screw extruder at a temperature of 180°C in step (1).

[0138] 3D mesh sample C-2

[0139] 3D mesh sample C-2 was prepared by the above general blow process wherein TPLI-C granulate was melted through a single screw extruder at a temperature of 170°C in step (1).

[0140] 3D mesh sample D

[0141] 3D mesh sample D was prepared by the above general blow process wherein TPLI-D granulate was melted through a single screw extruder at a temperature of 190°C in step (1).

[0142] 3D mesh E

[0143] 3D mesh sample E was prepared by the above general blow process wherein POE granulate was melted through a single screw extruder at a temperature of 190°C-200°C.

[0144] The obtained 3D mesh samples B-1 , B-2, C-1 and C-2 were tested based on industrial standard fatigue test according to DIN EN ISO 2439, B and the obtained results are shown in Table 3 below:

[0145] Table 3

[0146] As shown in Table 3, all 3D mesh samples showed good compression hardness performances. Further, it was found that the 3D mesh sample B-2 prepared under a lower temperature showed a lower compression hardness change ratio relative to the 3D mesh sample B-1. It also showed that the 3D mesh samples prepared under a lower temperature has a more constant performance during its lifetime due to the relative lower compression hardness change ratio after fatigue test. Table 4

[0147] As shown in Table 4, all 3D mesh samples showed lower thickness change ratio and good compression set performances. Table 5

[0148] As shown in Table 5, while TPLI-A has a lowest shore hardness as shown in Table 2, but 3D mesh sample A formed of TPLI-A has a highest compression hardness under 65% deformation. Further, for the 3D mesh samples A and C2, the initial compression hardness at 25% and 40% are much lower than 3D mesh sample E, while the compression hardness at 65% is on the same level as 3D mesh sample E, which indicates much softer touch feeling at the beginning of compressing and similar supporting force at the end of compressing relative to 3D mesh sample E. Table 5 also shows that while the comparative 3D mesh sample D has softer touch feeling at the beginning of compressing, but the supporting force at the end of compressing is poorer due to the lower compression hardness at 65% compression. Table 6

[0149] As shown in Table 6, the inventive 3D mesh samples A and C2 show lower thickness change ratio after fatigue test, compression set and hysteresis loss, while the comparative 3D mesh sample D shows higher thickness change ratio after fatigue test, compression set and hysteresis loss. Further, the lower hysteresis loss of 3D mesh samples A and C2 indicates a better resilience and rebound ability than 3D mesh samples D and E.

[0150] Table 7

[0151] Figure 1 indicates the compression force response of different 3D mesh samples measured by Dynamic mechanical analysis (RSA-G2 from TA). As shown in Figure 1 and Table 7, the inventive 3D mesh samples A and C2 show higher comfort factor, which means better comfort level.

[0152] Table 8

[0153] The average soft touch feeling rating (range from 1 to 5) gathered from 10 people (5 women and 5 men, age ranging from 20 to 50) indicates that the inventive 3D mesh samples have better soft touch feeling relative to 3D mesh sample E and the comparative 3D mesh sample D. Table 9

[0154] As shown in Table 9, the inventive 3D mesh samples A and C2 show better quietness relative to 3D mesh sample E.

[0155] It will be apparent to one of ordinary skill in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the present invention. It is intended that the embodiments and examples be considered as exemplary only. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.

Claims

Claims:

1. A 3D network structure comprising a thermoplastic polyurethane, wherein the thermoplastic polyurethane has a hardphase ratio ranging from 10wt% to 40wt% and wherein the thermoplastic polyurethane has a processing temperature window at which the thermoplastic polyurethane has a viscosity ranging from 103Pa s to 105Pa s.

2. The 3D network structure according to claim 1 , wherein the components for forming the thermoplastic polyurethane comprise(a) a polyol;(b) an isocyanate; and(c) a chain extender, preferably,(a) 45wt% to 80wt% of a polyol;(b) 15wt% to 50wt% of an isocyanate; and(c) 1wt% to 11wt% of a chain extender, wherein the wt% is based on the weight sum of each component.

3. The 3D network structure according to claim 2, wherein the components for forming the thermoplastic polyurethane further comprise (d) an additive.

4. The 3D network structure according to claim 3, wherein the additive comprises a chain regulator, a lubricant, a surfactant, a preservative, a pigment, a colorant, an antioxidant, a wax, an anti-ultraviolet additive, a stabilizer, a thickener, a wetting agent, a filler, a reinforcing agent, or a mixture thereof.

5. The 3D network structure according to claim 4, wherein the additive is selected from the group consisting of a chain regulator, a lubricant, an antioxidant, an anti-ultraviolet additive, or a mixture thereof.

6. The 3D network structure according to claim 5, wherein the chain regulator is an alkyl monohydric alcohol having carbon atoms of 2-30, preferably 4-26, and more preferably IQ- 22.

7. The 3D network structure according to any of claims 1 to 6, wherein the thermoplastic polyurethane has a processing temperature window at which the thermoplastic polyurethane has a viscosity ranging from 5x103Pa s to 5*104Pa s.

8. The 3D network structure according to any of claims 1 to 7, wherein the thermoplastic polyurethane has a hardphase ratio ranging from 15wt% to 40wt%, preferably from 20wt% to 40wt%.

9. The 3D network structure according to any of claims 1 to 8, wherein the thermoplastic polyurethane is processed at a temperature ranging from 80 °C to 260 °C, preferably from 120 °C to 220 °C, more preferably from 165 °C to 190 °C to form the 3D network structure.

10. The 3D network structure according to any of claims 1 to 9, wherein the thermoplastic polyurethane has a shore hardness ranging from 60A to 95A, preferably from 65A to 95A, more preferably from 70A to 90A.

11. The 3D network structure according to any of claims 2 to 10, wherein the polyol has a number average molecular weight (Mn) ranging from 500 to 5000, preferably from 700 to 4000, more preferably from 800 to 3000, most preferably from 900 to 1200.

12. The 3D network structure according to any of claims 2 to 11, wherein the polyol is selected from a polyether polyol and a polyester polyol, preferably the polyol is selected from polyether polyol derived from oxygen-containing heterocyclic compounds comprising 2 to 6 carbon atoms, preferably tetrahydrofuran, or is selected from polyether polyol derived from epoxides, preferably ethylene oxide, propylene oxide or a mixture thereof.

13. The 3D network structure according to any of claims 2 to 12, wherein the polyol has a functionality in the range of from 1.5 to 2.5, preferably a functionality in the range of from 1.8 to 2.1.

14. The 3D network structure according to any of claims 2 to 13, wherein the isocyanate comprises aromatic diisocyanate, preferably diphenylmethane diisocyanate.

15. The 3D network structure according to any of claims 1 to 14, wherein the 3D network structure is a 3D mesh.

16. An article comprising a 3D network structure as defined in any of claims 1 to 15.

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