3D network structure with high rebound resilience, soft touch feeling and good silence and preparation method thereof

Abstract

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

Description

Technical Field

[0001] The present invention relates to a three-dimensional (3D) network structure comprising thermoplastic polyurethane and a method for preparing the 3D network structure. Background Art

[0002] Three-dimensional (3D) meshes have a 3D network structure and are widely used in applications such as mattresses and chair cushions. Currently, 3D meshes are primarily made from polyethylene (PE), polyolefin elastomers (POE), or thermoplastic polyetherester elastomers (TPEE). However, these 3D meshes have poor tactile feel and quietness.

[0003] Thermoplastic polyurethane (TPU) is a type of elastomer that possesses excellent properties such as high strength, high toughness, wear resistance, oil resistance, antibacterial properties, and good processability, and is widely used in many fields such as sports, medical care, and food. However, only a few patents have disclosed the application of TPU in 3D meshes.

[0004] US 2015 / 0087196 A1 discloses an elastic network structure comprising a three-dimensional random ring-bonded structure composed of continuous linear structures. This patent generally states that the thermoplastic resin used to form the network structure is at least one thermoplastic resin selected from the group consisting of soft polyolefins, polystyrene thermoplastic elastomers, polyester thermoplastic elastomers, polyurethane thermoplastic elastomers, and polyamide thermoplastic elastomers. The patent also provides specific examples of network structures prepared using polyester thermoplastic elastomers. However, this document does not provide any examples of network structures prepared using polyurethane thermoplastic elastomers.

[0005] US 2016 / 0237603 A1 discloses a network structure composed of a three-dimensional random ring-bonded structure obtained by curling a continuous linear structure to form random rings. The continuous linear structure comprises at least one thermoplastic elastic resin selected from the group consisting of polyolefin-based thermoplastic elastomers, ethylene-vinyl acetate copolymers, polyurethane-based thermoplastic elastomers, and polyamide-based thermoplastic elastomers. This document measures the repeated compression durability and repellency properties of the resulting cushion. However, this document does not mention the cushion's tactile feel or quietness.

[0006] Since high resilience, soft touch and good quietness are important for the application of 3D network structures, there is still a need to provide a 3D network structure having high resilience, soft touch and good quietness. Summary of the Invention

[0007] The object of the present invention is to provide a 3D network structure with high resilience, soft touch and good quietness.

[0008] Therefore, the present invention provides a 3D network structure comprising a thermoplastic polyurethane, wherein the thermoplastic polyurethane has a hard phase ratio ranging from 10 wt % to 40 wt %, and wherein the thermoplastic polyurethane has a processing temperature window, under which the thermoplastic polyurethane has a hard phase ratio ranging from 10 wt % to 40 wt %. 3 Pa s to 10 5 Pa s viscosity.

[0009] The present invention also provides a product comprising the 3D network structure.

[0010] It has been found that the 3D network structure of the present invention shows high resilience, soft touch and good quietness. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 Indicated are the compressive force responses of different 3D mesh samples measured by dynamic mechanical analysis. DETAILED DESCRIPTION

[0012] The present invention will be described in detail below. It should be understood that the present invention can be implemented in many different ways and should not be construed as limited to the embodiments set forth herein.

[0013] Unless defined otherwise, all technical and scientific terms used herein have the meaning commonly understood by one of ordinary skill in the art to which the invention belongs. As used herein, the following terms have the meanings ascribed to them below unless otherwise indicated.

[0014] As used herein, the articles "a" and "an" refer to one or to more than one (ie, to at least one) of the grammatical object of the article or component.

[0015] As used herein, the terms "comprise," "comprising," and the like are used interchangeably with "contain," "containing," and the like and are to be interpreted in a non-limiting, open-ended manner. That is, for example, additional components or elements may be present. The expression "consisting of" or "consisting essentially of," or cognates thereof, may be included within "comprises" or cognates.

[0016] Unless otherwise stated, all percentages (%) are "percentages by weight".

[0017] Unless otherwise stated, the molecular weight of each component or polymer is meant to be the number average molecular weight (Mn).

[0018] In the present invention, the molecular weight of each component or polymer is determined using gel permeation chromatography (GPC) according to GB / T 21863-2008.

[0019] In the present invention, the OH number of each polyol is determined according to DIN 53240.

[0020] In the present invention, the hardness ratio (wt%) of TPU is calculated according to the following formula:

[0021]

[0022] n 扩链剂 represents the number of moles of chain extender;

[0023] M 扩链剂 represents the molecular weight of the chain extender;

[0024] M 异氰酸酯 represents the molecular weight of the isocyanate; and

[0025] The total mass represents the sum of the masses of chain extender, isocyanate and polyol that react during polymerization.

[0026] The processing temperature window is defined by the temperature range of the TPU, within which the TPU has a 10 3 Pa s to 10 5 Pa s, where the viscosity of TPU is measured by a capillary flow tester (CFT-500D from Shimazu) based on a weight load of 30 kg in accordance with JIS K 7311 and JIS K 7210.

[0027] In the present invention, the functionality (Fn) of a polyol refers to the number of terminal hydroxyl groups per polyol molecule. Functionality is determined by the following formula:

[0028] Fn = M n *(OHv) / 56100

[0029] Among them, M n represents the number average molecular weight of the polyol and OHv represents the OH value of the polyol.

[0030] In the present invention, the industry standard fatigue test was performed according to DIN EN ISO 2439, B.

[0031] In the present invention, hysteresis losses are measured according to DIN EN ISO 2439, B.

[0032] In the present invention, compression set is measured according to ISO 1856:2018 - Method A, 70°C.

[0033] In the present invention, noise levels were measured using an SW6004 digital sound level meter available from Dongguan Wanchuang Electronic Products Co., Ltd. by repeatedly pressing the 3D mesh sample 20 times while the meter was placed 5 mm away from the sample. The maximum noise level was recorded, and the average of the three measurements was calculated to obtain the noise level. A lower noise level indicates better quietness.

[0034] In the present invention, the ratio of the stress of the 3D mesh sample under 40% compression to the stress of the 3D mesh sample under 10% compression is defined as a comfort factor indicating the comfort level of the 3D mesh sample, where a higher comfort factor indicates a better comfort level of the 3D mesh sample.

[0035] In the present invention, soft touch was measured by hand by 10 persons (5 females and 5 males, ranging in age from 20 to 50 years old), and was classified into a scale ranging from 1 to 5, with 5 indicating the highest (best) soft touch and 1 indicating the lowest soft touch.

[0036] Polyol (a)

[0037] In the present invention, the components used to form the thermoplastic polyurethane may include a polyol. The polyol may have a number average molecular weight (Mn) ranging from 500 to 5000, preferably from 700 to 4000, more preferably from 800 to 3000, and most preferably from 900 to 1200, such as 600, 900, 1000, 1100, 1200, 1300, 1400, 1500, 2000, 2500, 3000, 3500, 4000, 4500, 5000, etc.

[0038] The polyol can be a polyol conventionally used for thermoplastic polyurethanes, such as polyether polyols, polyester polyols, such as polycaprolactone polyols, polycarbonate polyols, and combinations thereof, preferably polyether polyols. Preferably, the polyol can be polyether diols, polyester diols, polycarbonate diols, and combinations thereof.

[0039] The polyol in the present invention may be produced by a method known in the art or may be commercially available.

[0040] In embodiments, the polyol may be selected from polyether polyols derived from oxygen-containing heterocyclic compounds containing 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 a repeating unit and is preferably terminated with primary hydroxyl groups. In a preferred embodiment, the polytetrahydrofuran (PTHF) has a functionality of 2, a number average molecular weight (Mn) of 975 to 1025 g / mol, and an OH value (OHv) of 109.5 to 115.1 mg KOH / g, such as PTHF1000 from BASF.

[0041] In a preferred embodiment, the polyol is selected from polyether polyols derived from epoxides, preferably ethylene oxide, propylene oxide or mixtures thereof.

[0042] In an embodiment, the polyol can be selected from polyester polyols, including those obtained, for example, from dicarboxylic acids and polyols having 2 to 12 carbon atoms, preferably 4 to 6 carbon atoms. 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. In order to prepare polyester polyols, corresponding dicarboxylic acid derivatives can also be optionally used, such as carboxylic acid diesters, anhydrides, or acid chlorides having 1 to 4 carbon atoms in the alcohol residue instead of the dicarboxylic acid. The example of suitable polyol comprises the glycol with 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-propylene glycol or dipropylene glycol.Depending on the desired property, polyester polyol can be used alone or as a mixture.Preferred polyester polyol comprises 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, ω-hydroxycarboxylic acid such as condensation product of ω-hydroxycaproic acid or lactone such as the polymerization product of optionally substituted ω-caprolactone.

[0043] In an embodiment, the polyol may be selected from polycarbonate polyols derived from carbonic acid and diols, especially diols having 4 to 6 carbon atoms such as 1,4-butanediol or 1,6-hexanediol.

[0044] The polyol is preferably used in an amount of 45 to 80 wt %, such as 45 wt %, 50 wt %, 55 wt %, 60 wt %, 65 wt %, 70 wt %, 75 wt %, 80 wt %, etc., based on the total weight of the thermoplastic polyurethane.

[0045] Isocyanate (b)

[0046] In the present invention, the components for forming the thermoplastic polyurethane may include isocyanates. The isocyanates may include all isocyanates known for use in the production of polyurethanes. These isocyanates include aliphatic, alicyclic, araliphatic and / or aromatic isocyanates, such as tri-, tetra-, penta-, hexa-, hepta- and / or octamethylene diisocyanate, 2-methylpentamethylene 1,5-diisocyanate, 2-ethylbutene 1,4-diisocyanate, pentamethylene 1,5-diisocyanate, butene 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. cyanates, 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, naphthalene 1,5-diisocyanate (NDI), toluene 2,4- and / or 2,6-diisocyanate (TDI), 3,3'-dimethyldiphenyl diisocyanate, 1,2-diphenylethane diisocyanate and / or phenylene diisocyanate, or mixtures thereof.

[0047] Preferably, the isocyanate comprises MDI, particularly 4,4'-diphenylmethane diisocyanate.

[0048] The isocyanate is preferably used in an amount of 15 to 50 wt %, such as 15, 20, 25, 30, 35, 40, 45, 50, etc., based on the total weight of the thermoplastic polyurethane.

[0049] Chain extender (c)

[0050] In the present invention, the components used to form the thermoplastic polyurethane may include a chain extender.

[0051] Chain extenders that can be used are substances having a molar mass of preferably less than 500 g / mol, particularly preferably in the range of 60 to 400 g / mol, wherein the chain extenders have two or more (for example, three) hydrogen atoms that are reactive toward isocyanates. These chain extenders can be used individually or in mixtures. Preference is given to using diols with a molecular weight of less than 500, particularly 60 to 400, and especially 60 to 350. Examples of diols that can be used are aliphatic, cycloaliphatic, and / or araliphatic diols having 2 to 14, preferably 2 to 10, carbon atoms, such as ethylene glycol, 1,3-propylene glycol, 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, and diethanolamine. Preference is given to using ethylene glycol, 1,3-propylene glycol or 1,4-butanediol, especially 1,4-butanediol.

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

[0053] Additive (d)

[0054] In the present invention, the thermoplastic polyurethane may optionally contain additives.

[0055] Additives that can be used in the present invention include chain regulators, lubricants, surfactants, preservatives, pigments, colorants, antioxidants, waxes, UV-resistant additives, stabilizers, thickeners, wetting agents, fillers, and reinforcing agents, or mixtures thereof. When preparing thermoplastic polyurethane, it is preferred to use one of the above additives or a mixture thereof.

[0056] The additive is typically used in an amount of 0 wt % to 12 wt %, such as 0.1 wt % to 10 wt %, based on the total weight of the thermoplastic polyurethane.

[0057] According to the present invention, chain regulators, lubricants, antioxidants and anti-UV additives are preferably used. The amount of each of them is preferably 0.1 wt % to 5 wt %, more preferably 0.1 wt % to 1.5 wt %, each based on the total weight of the thermoplastic polyurethane.

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

[0059] As the antioxidant, all compounds commonly used in the preparation of polyurethanes can be used, such as tea polyphenols (TP), tocopherols, flavonoids, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), tert-butylhydroquinone (TBHQ), etc. The amount of the antioxidant (if present) is preferably 0.1 wt% to 5 wt%, more preferably 0.1 wt% to 1.5 wt%, such as 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1.0 wt%, 1.2 wt%, 1.3 wt%, 1.4 wt%, etc., based on the total weight of the thermoplastic polyurethane.

[0060] As lubricants, all compounds commonly used for preparing polyurethanes can be used. The amount of lubricant (if present) is preferably 0.1 wt% to 5 wt%, more preferably 0.1 wt% to 1.0 wt%, such as 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, etc., based on the total weight of the thermoplastic polyurethane.

[0061] As anti-UV additives, all compounds suitable for the preparation of polyurethanes can be used, such as salicylates, phenyl ketones, benzotriazoles, substituted acrylonitriles, triazines, etc. The amount of the anti-UV additive (if present) is preferably 0.1 wt% to 5 wt%, more preferably 0.1 wt% to 1 wt%, such as 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, etc., based on the total weight of the thermoplastic polyurethane.

[0062] Catalyst (e)

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

[0064] As catalysts, all compounds that can accelerate the reaction between isocyanates and polyols can be used. Such compounds are known and described, for example, in "Kunststoffhandbuch [Plastics Handbook], Volume 7, Polyurethane [Polyurethane]", Carl Hanser Verlag [Karl Hanser Publishing House], 3rd edition, 1993, Chapter 3.4.1. These catalysts include amine-based catalysts and organometallic compound-based catalysts or mixtures 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, dimethylcyclohexylamine, trimethylhydroxyethylethylenediamine, 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 organometallic compounds, it is possible to use, for example, organotin compounds such as tin(II) salts of organic carboxylic acids, for example tin(II) acetate, tin(II) octoate, tin(II) ethylhexanoate and tin(II) laurate; and dialkyltin(IV) salts of organic carboxylic acids, for example dibutyltin diacetate, dibutyltin dilaurate, dibutyltin maleate and dioctyltin diacetate; and also Zn or Bi salts, for example zinc octoate, bismuth(III) neodecanoate, bismuth 2-ethylhexanoate and bismuth octoate; or alkali metal salts of carboxylic acids, for example potassium acetate or potassium formate.

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

[0068] Thermoplastic polyurethane

[0069] In the present invention, the thermoplastic polyurethane has a hard phase ratio ranging from 10 wt % to 40 wt %, preferably from 15 wt % to 40 wt %, more preferably from 20 wt % to 40 wt %, such as 12 wt %, 14 wt %, 15 wt %, 16 wt %, 18 wt %, 20 wt %, 22 wt %, 24 wt %, 26 wt %, 28 wt %, 30 wt %, 32 wt %, 34 wt %, 36 wt %, 38 wt %, 40 wt %, etc.

[0070] In the present invention, the thermoplastic polyurethane has a processing temperature window, under which the thermoplastic polyurethane has a range from 10 3 Pa s to 10 5 Pa s, preferably 5 × 10 3 Pa s to 5 × 10 4 Pa 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. viscosity.

[0071] 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 in the processing temperature window, preferably at a temperature closer to the lower limit of the processing temperature window, to form a 3D network structure.

[0072] 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.

[0073] Thermoplastic polyurethanes are typically prepared by reacting polyols, isocyanates, and chain extenders, optionally with additives, and optionally with catalysts, using methods known in the art. In one embodiment of the present invention, the TPU resin is prepared by mixing polyols, isocyanates, and chain extenders with additives such as chain regulators, antioxidants, lubricants, and UV-resistant additives. The resulting mixture is pulled onto a conveyor belt and conveyed to a heating zone with infrared heating elements. After heating, the mixture is chopped / ground into fragments / granules and optionally melted through an extruder for further granulation using an underwater granulation system. The resulting granules are optionally further dried through a fluidized bed to further build their molecular weight and remove absorbed water. Thermoplastic polyurethanes can also be prepared by a reactive extruder process.

[0074] 3D network structure

[0075] The 3D network structure is produced by extruding a thermoplastic resin through a die containing multiple holes to form a random 3D structure. The continuous 3D structures are further stacked and bonded to form a continuous 3D mesh. The 3D network structure (3D mesh) can be produced by methods known in the art, such as those described in TW 201538306 A, which is incorporated herein by reference.

[0076] In a preferred embodiment, the 3D network structure is prepared by a blow molding process comprising the following steps:

[0077] (1) Melting TPU resin pellets through a single-screw extruder;

[0078] (2) converting the TPU resin melt into multiple melt streams through a die;

[0079] (3) The melt flow is spiraled and stacked on the surface of a water bath placed below the die, forming a stacked 3D network structure;

[0080] (4) pulling the stacked 3D network structure into a water bath by two rollers placed at the water surface, and rolling toward the water bath for cooling, wherein the distance between the two rollers is set to a target thickness of the 3D network structure; and

[0081] (5) The formed 3D network structure is pulled out of the water bath and further dried to obtain the final product.

[0082] The 3D network structure according to the present invention has excellent resilience, soft touch and good quietness. These excellent properties make it possible to provide a network structure suitable for cushioning materials, which can be used in beds, office chairs, furniture, sofas, vehicle seats, floor mats, etc.

[0083] Example

[0084] Various embodiments are listed below. It will be understood that the embodiments listed below can be combined with all aspects of the scope of the present invention and other embodiments.

[0085] Embodiment 1. A 3D network structure comprising a thermoplastic polyurethane, wherein the thermoplastic polyurethane has a hardness ratio ranging from 10 wt % to 40 wt %, and wherein the thermoplastic polyurethane has a processing temperature window, under which the thermoplastic polyurethane has a hardness ratio ranging from 10 wt % to 40 wt %. 3 Pa s to 10 5 Pa s viscosity.

[0086] Example 2. The 3D network structure according to Example 1, wherein the components used to form the thermoplastic polyurethane include

[0087] (a) polyols;

[0088] (b) isocyanates; and

[0089] (c) chain extenders,

[0090] Preferably,

[0091] (a) 45 wt % to 80 wt % of a polyol;

[0092] (b) 15 wt% to 50 wt% of an isocyanate; and

[0093] (c) 1 wt% to 11 wt% of a chain extender,

[0094] The wt% is based on the total weight of each component.

[0095] Embodiment 3. The 3D network structure according to embodiment 2, wherein the components for forming the thermoplastic polyurethane further include (d) an additive.

[0096] 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-UV additive, a stabilizer, a thickener, a wetting agent, a filler, a reinforcing agent, or a mixture thereof.

[0097] 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 anti-UV additive, or a mixture thereof.

[0098] Embodiment 6. The 3D network structure according to embodiment 5, wherein the chain regulator is an alkyl monoalcohol having 2-30, preferably 4-26, and more preferably 10-22 carbon atoms.

[0099] Embodiment 7. The 3D network structure according to any one of embodiments 1 to 6, wherein the thermoplastic polyurethane has a processing temperature window, under which the thermoplastic polyurethane has a range from 5 × 10 3 Pa s to 5 × 10 4 Pa s viscosity.

[0100] Embodiment 8. The 3D network structure according to any one of embodiments 1 to 7, wherein the thermoplastic polyurethane has a hard phase ratio ranging from 15 wt % to 40 wt %, preferably from 20 wt % to 40 wt %.

[0101] Embodiment 9. The 3D network structure according to any one 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.

[0102] Embodiment 10. The 3D network structure according to any one 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.

[0103] Embodiment 11. The 3D network structure according to any one 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.

[0104] Embodiment 12. The 3D network structure according to any one of embodiments 2 to 11, wherein the polyol is selected from polyether polyols and polyester polyols, preferably, the polyol is selected from polyether polyols derived from oxygen-containing heterocyclic compounds containing 2 to 6 carbon atoms, preferably tetrahydrofuran, or from polyether polyols derived from epoxides, preferably ethylene oxide, propylene oxide or mixtures thereof.

[0105] Embodiment 13. The 3D network structure according to any one of embodiments 2 to 12, wherein the polyol has a functionality ranging from 1.5 to 2.5, preferably a functionality ranging from 1.8 to 2.1.

[0106] Embodiment 14. The 3D network structure according to any one of embodiments 2 to 13, wherein the isocyanate comprises an aromatic diisocyanate, preferably diphenylmethane diisocyanate.

[0107] Embodiment 15 The 3D network structure according to any one of embodiments 1 to 14, wherein the 3D network structure is a 3D mesh.

[0108] Embodiment 16. An article comprising a 3D network structure as defined in any one of embodiments 1 to 15.

[0109] Examples

[0110] The present invention will now be described with reference to Examples and Comparative Examples, which are not intended to limit the present invention.

[0111] raw material

[0112] PTHF1000 is polytetrahydrofuran from BASF.

[0113] MDI (4,4'-diphenylmethane diisocyanate) is an isocyanate from BASF.

[0114] 1,4-Butanediol (1,4-BDO) is a chain extender.

[0115] 1-Tetradecanol was from Sasol.

[0116] The polyolefin elastomer (POE) was TAFMER DF940 from Mitsui Chemicals.

[0117] Preparation of TPU

[0118] TPU is prepared according to a general method comprising the following steps:

[0119] (1) optionally mixing an additive (chain regulator) with the polyol and dissolving the additive in the polyol;

[0120] (2) Separately, preheat the mixed polyol and chain extender to 80°C and preheat the isocyanate to 50°C;

[0121] (3) Mixing the preheated polyol, chain extender, and isocyanate together in a container under vigorous stirring;

[0122] (4) When the temperature of the mixture reaches 110°C, pour the mixture from the container onto a hot plate set at 135°C for 10 min until the mixture solidifies into a TPU sheet;

[0123] (5) moving the obtained TPU sheet into an oven set at 80°C and annealing for 12 hours; and

[0124] (6) After annealing, the TPU sheet was ground into particles for further processing to produce 3D meshes.

[0125] TPU-A, TPU-B, TPU-C, and TPU-D were prepared by the above general method according to the components and amounts shown in the following Table 1. The samples made of TPU-A, TPU-B, and TPU-C are examples according to the present invention, and the sample made of TPU-D is a comparative example.

[0126] Table 1

[0127]

[0128] The properties of the resulting TPU are shown in Table 2 below.

[0129] Table 2

[0130]

[0131] Table 2 shows that TPU-A, TPU-B, and TPU-C have lower processing temperature windows relative to TPU-D. In particular, TPU-C shows the lowest processing temperature window.

[0132] Example 1 - Preparation of 3D mesh samples

[0133] The 3D mesh samples were prepared by a general blow molding process comprising the following steps:

[0134] (1) Melting TPU pellets through a single-screw extruder at a certain temperature;

[0135] (2) converting the TPU melt into multiple melt streams through a die;

[0136] (3) spiraling the melt flow and stacking it on a surface of a water bath placed below the die head to form a stacked 3D grid sample, wherein the water bath has a temperature of 10°C;

[0137] (4) pulling the stacked 3D mesh sample into a water bath by two rollers placed at the water surface, and rolling toward the water bath for cooling, wherein the distance between the two rollers is set to the target thickness of the 3D mesh sample, wherein the linear speed of the two rollers is 1 m / min and the distance between the two rollers is 5 cm; and

[0138] (5) The formed 3D mesh sample was pulled out from the water bath and further dried at room temperature (RT) to obtain the final product.

[0139] 3D Mesh Sample A

[0140] The 3D mesh sample A was prepared by the above general blow molding process, where in step (1), TPU-A pellets were melted at a temperature of 180°C by a single screw extruder.

[0141] 3D mesh sample B-1

[0142] The 3D mesh sample B-1 was prepared by the above general blow molding process, wherein in step (1), TPU-B pellets were melted by a single screw extruder at a temperature of 190°C.

[0143] 3D mesh sample B-2

[0144] The 3D mesh sample B-2 was prepared by the above general blow molding process, where in step (1), TPU-B pellets were melted by a single screw extruder at a temperature of 180°C.

[0145] 3D mesh sample C-1

[0146] The 3D mesh sample C-1 was prepared by the above general blow molding process, where in step (1), TPU-C pellets were melted at a temperature of 180°C by a single screw extruder.

[0147] 3D mesh sample C-2

[0148] The 3D mesh sample C-2 was prepared by the above general blow molding process, where in step (1), TPU-C pellets were melted by a single screw extruder at a temperature of 170°C.

[0149] 3D Grid Sample D

[0150] The 3D mesh sample D was prepared by the above general blow molding process, where in step (1), TPU-D pellets were melted at a temperature of 190°C by a single screw extruder.

[0151] 3D Mesh Sample E

[0152] The 3D mesh sample E was prepared by the above general blow molding process, in which POE pellets were melted by a single screw extruder at a temperature of 190°C-200°C.

[0153] The obtained 3D mesh samples B-1, B-2, C-1 and C-2 were tested based on the industry standard fatigue test according to DIN EN ISO 2439, B, and the obtained results are shown in Table 3 below:

[0154] Table 3

[0155]

[0156] As shown in Table 3, all 3D mesh samples exhibited good compressive hardness performance. Furthermore, it was found that 3D mesh sample B-2, prepared at a lower temperature, exhibited a lower compressive hardness change ratio relative to 3D mesh sample B-1. Furthermore, due to the relatively low compressive hardness change ratio after fatigue testing, the 3D mesh samples prepared at a lower temperature exhibited more consistent performance over their lifetime.

[0157] Table 4

[0158]

[0159] As shown in Table 4, all 3D mesh samples showed low thickness variation ratio and good compression set performance.

[0160] Table 5

[0161]

[0162] As shown in Table 5, although TPU-A has the lowest Shore hardness as shown in Table 2, 3D mesh sample A formed from TPU-A has the highest compression hardness at 65% deformation. In addition, for 3D mesh samples A and C2, the initial compression hardness at 25% and 40% is much lower than that of 3D mesh sample E, while the compression hardness at 65% is at the same level as 3D mesh sample E, indicating that the touch at the beginning of compression is much softer than that of 3D mesh sample E, and the support force at the end of compression is similar. Table 5 also shows that although comparative 3D mesh sample D has a softer touch at the beginning of compression, the support force at the end of compression is poor due to the lower compression hardness at 65% compression.

[0163] Table 6

[0164]

[0165] As shown in Table 6, the inventive 3D mesh samples A and C2 exhibited lower thickness change ratios, compression set, and hysteresis loss after fatigue testing, while the comparative 3D mesh sample D exhibited higher thickness change ratios, compression set, and hysteresis loss after fatigue testing. Furthermore, the lower hysteresis loss of 3D mesh samples A and C2 indicates better resilience and rebound capabilities than 3D mesh samples D and E.

[0166] Table 7

[0167]

[0168] Figure 1The compressive force response of different 3D mesh samples measured by dynamic mechanical analysis (RSA-G2 from TA Instruments) is indicated. Figure 1 As shown in Table 7, the 3D mesh samples A and C2 of the present invention show higher comfort factors, which means better comfort levels.

[0169] Table 8

[0170]

[0171] The average soft touch ratings (ranging from 1 to 5) collected from 10 individuals (5 females and 5 males, ranging in age from 20 to 50 years old) indicated that the inventive 3D mesh sample had a better soft touch than 3D mesh sample E and comparative 3D mesh sample D.

[0172] Table 9

[0173]

[0174] As shown in Table 9, the 3D mesh samples A and C2 of the present invention show better quietness relative to the 3D mesh sample E.

[0175] It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. It is intended that the embodiments and examples be considered as illustrative only. Therefore, the present invention is intended to cover such modifications and variations as come within the scope of the appended claims and their equivalents.

Claims

1. A 3D network structure comprising a thermoplastic polyurethane, wherein the thermoplastic polyurethane has a hardness ratio ranging from 10 wt % to 40 wt %, and wherein the thermoplastic polyurethane has a processing temperature window, under which the thermoplastic polyurethane has a hardness ratio ranging from 10 wt % to 40 wt %. 3 Pa s to 10 5 Pa s viscosity.

2. The 3D network structure according to claim 1, wherein: The components used to form the thermoplastic polyurethane include (a) polyols; (b) isocyanates; and (c) chain extenders, Preferably, (a) 45 wt % to 80 wt % of a polyol; (b) 15 wt% to 50 wt% of an isocyanate; and (c) 1 wt% to 11 wt% of a chain extender, The wt% is based on the total weight of each component.

3. The 3D network structure according to claim 2, wherein: The components used to form the thermoplastic polyurethane further include (d) additives.

4. The 3D network structure according to claim 3, wherein: The additives include chain regulators, lubricants, surfactants, preservatives, pigments, colorants, antioxidants, waxes, UV protection additives, stabilizers, thickeners, wetting agents, fillers, reinforcing agents, or mixtures thereof.

5. The 3D network structure according to claim 4, wherein: The additive is selected from the group consisting of chain regulators, lubricants, antioxidants, anti-UV additives, or mixtures thereof.

6. The 3D network structure according to claim 5, wherein: The chain regulator is an alkyl monoalcohol having 2 to 30, preferably 4 to 26, and more preferably 10 to 22 carbon atoms.

7. The 3D network structure according to any one of claims 1 to 6, wherein: The thermoplastic polyurethane has a processing temperature window, within which the thermoplastic polyurethane has a range from 5 × 10 3 Pa s to 5 × 10 4 Pa s viscosity.

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

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

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

1.

14. The 3D network structure according to any one of claims 2 to 13, wherein: The isocyanate includes aromatic diisocyanates, preferably diphenylmethane diisocyanate.

15. The 3D network structure according to any one of claims 1 to 14, wherein: The 3D network structure is a 3D grid.

16. An article comprising the 3D network structure according to any one of claims 1 to 15.

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