Polyurethane composition for rotational molding and use thereof

Abstract

Disclosed is a two-component polyurethane system for rotational molding, the two-component polyurethane system comprising: a polyol component, the polyol component comprises a high functionality polyol having a functionality greater than 3.5, a polyol of biological origin, a viscosity modifier, a chain extender in an amount of from 10 wt% to 20 wt% based on the total weight of the polyol component, an amine catalyst, and a rheology modifier; and a diisocyanate or polyisocyanate component. An article produced from the two-component polyurethane system and a method of producing the same are also provided.

Description

Technical Field

[0001] The present disclosure relates to a polyurethane composition for rotational molding, in particular a polyurethane composition for rationally molding hollow bodies such as clothing mannequins, and uses of the polyurethane composition. Background Art

[0002] Hollow bodies (such as clothing mannequins, mannequins for entertainment or education) are widely used. Currently, mannequins are mostly made of fiber-reinforced plastics in manual production. The manual production process is inefficient. Due to the volatility of molding materials, reagents and additives, workers are often faced with an uncomfortable and unsafe atmosphere or environment. Rotational molding processes using polymer compositions are much more efficient and operator-friendly.

[0003] However, conventional PU compositions contain hazardous chemicals such as heavy metal catalysts, plasticizers, etc. Additionally, in the rotational molding process, it is difficult to achieve a thin coating with uniform thickness.

[0004] WO2021 / 114664A1 discloses a polyurethane elastomer for manufacturing a fast-demolding, high-temperature-resistant, transparent model material.

[0005] CN102040824B discloses a casting polyurethane elastomer composition for a human body model. The casting polyurethane elastomer composition is a two-component system. Summary of the Invention

[0006] An object of the present disclosure is to overcome the problems of the prior art discussed above and to provide a polyurethane composition which, when processed into a hollow body, allows for a thin layer coating with uniform and reduced thickness. The composition contains raw materials of biological origin and is substantially free of metal-based catalysts.

[0007] Surprisingly, the inventors have found that the above objects can be achieved by a two-component polyurethane system for rotational molding, comprising:

[0008] A polyol component comprising

[0009] High-functionality polyols with a functionality greater than 3.5,

[0010] Bio-derived polyols,

[0011] Viscosity modifiers,

[0012] 10 to 20 wt% of a chain extender based on the total weight of the polyol component,

[0013] Amine catalysts,

[0014] rheology modifiers; and

[0015] Diisocyanate or polyisocyanate component.

[0016] In another aspect, the present disclosure provides an article produced from the polyurethane system.

[0017] In another aspect, the present disclosure provides a method for producing an article from the two-component polyurethane system, the method comprising:

[0018] Provide two-component polyurethane system;

[0019] placing the two-component polyurethane system in a hollow mold;

[0020] causing the hollow mold to rotate and the two-component polyurethane system to cure and form an article; and

[0021] Retrieve the product.

[0022] In this application it has been surprisingly found that this two-component polyurethane system can be cured quickly and can be used to produce hollow articles with uniform shell thickness by rotational molding. DETAILED DESCRIPTION

[0023] Unless otherwise defined, all technical and scientific terms used herein have the meanings commonly understood by those skilled in the art to which this disclosure belongs. As used herein, unless otherwise indicated, the following terms have the meanings assigned to them below.

[0024] 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. For example, "an element" means one element or more than one element.

[0025] Unless otherwise indicated, all percentages (%) are by weight.

[0026] Unless otherwise specified, a "polyether segment" refers to any divalent segment composed of one or more repeating alkylene oxide units. Alkylene oxides may include, but are not limited to, tetramethylene oxide, ethylene oxide, propylene oxide, butylene oxide, pentylene oxide, hexylene oxide, or styrene oxide. Polyether segments include, but are not limited to, for example -[CH2CH2CH2CH2O] a –, –[CH2CH2O] b –, –[CH2CH(CH3)O] c –, –[CH2CH2O] d [CH2CH(CH3)O] e - and / or any other combination of alkylene oxides, wherein a to e are independently an integer not less than 1.

[0027] Tetramethylene oxide is -CH2CH2CH2CH2O-.

[0028] Ethylene oxide (EO) is -CH2CH2O-.

[0029] Propylene oxide (PO) is -CH(CH3)CH2O- or -CH2CH(CH3)O-.

[0030] Butylene oxide (BO) is -CH(C2H5)CH2O-, -C(CH3)2CH2O-, -CH2C(CH3)2O-, -CH(CH3)CH(CH3)O- or -CH2CH(C2H5)O-.

[0031] Pentyl oxide is -CH(C3H7)CH2O-, -CH2CH(C3H7)O-, -CH(C2H5)CH(CH3)O-, -CH(CH3)CH(C2H5)O-, -C(CH3)(C2H5)CH2O-, -CH2C(CH3)(C2H5)O-, -C(CH3)2CH(CH3)O- or -CH2(CH3)C(CH3)2O-.

[0032] Epoxyhexane is -CH(C4H9)CH2O-, -CH2CH(C4H9)O-, -C(C3H7)(CH3)CH2O-, -CH2C(C3H7)(CH3)O-, -CH(C3H7)CH(CH3)O, -CH(CH3)CH(C3H7)O-, -C(C2H5)(C2H5)CH2O-, -CH2C(C2H5)2O-, -CH(C2H5)CH(C2H5)O-, -C(CH3)2CH(C2H5)O-, -CH(C2H5)C(CH3)2O- or -CH(CH3)2C(CH3)2O-.

[0033] Epoxyphenylethane is -CH(C6H5)CH2O- or -CH2CH(C6H5)O-.

[0034] The functionality or Fn of a polyol (including polyester polyols, polyether polyols or other types of polyols) is defined as the number of hydroxyl groups per molecule.

[0035] M n It is defined as the numerical average of the molecular weights.

[0036] The isocyanate index or NCO index is defined as the ratio of the number of NCO groups present in the formulation divided by the number of isocyanate-reactive hydrogen atoms, given as a percentage:

[0037] Isocyanate index = [NCO] × 100 (%) / [active hydrogen]

[0038] In other words, the isocyanate index expresses the percentage of isocyanate actually used in the formulation relative to the amount of isocyanate theoretically required to react with the amount of isocyanate-reactive hydrogen used in the formulation.

[0039] Polyurethanes are block polymers with soft and hard segments. The soft segments are derived from hydroxyl-terminated polyethers, polyesters, or polycarbonates. The hard segments are derived from isocyanates and chain extenders. The chain extenders are typically one or more small molecule diols, such as 1,3-propylene glycol or 1,4-butanediol.

[0040] Unless indicated otherwise, temperature is room temperature and pressure is ambient pressure.

[0041] Unless otherwise stated, solvents refer to all organic and inorganic solvents known to those skilled in the art and do not include monomeric molecules of any type.

[0042] Polyurethane system

[0043] According to the present disclosure, a polyurethane system comprises: a polyol component comprising a high-functionality polyol having a functionality greater than 3.5, a bio-derived polyol, a viscosity modifier, a chain extender present in an amount of 10 wt % to 20 wt % based on the total weight of the polyol component, an amine catalyst, and a rheology modifier; and an isocyanate component.

[0044] The polyol component and the isocyanate component can be stored separately prior to mixing and production of the article, as is generally known in the art.The polyurethane system can be mixed and poured, molded, sprayed or formed to form the article by any other method known to those skilled in the art.

[0045] Preferably, the isocyanate index of the two-component polyurethane system is in the range of from 80 to 120, preferably in the range of from 90 to 110.

[0046] Polyol components

[0047] High-functionality polyols

[0048] The polyol component includes a high-functionality polyol having a functionality greater than 3.5. The high-functionality polyol can be a polyether polyol, a polyester polyol, a polycarbonate polyol, a polybutadiene polyol, or any combination thereof. In the case of a polyether polyol, the high-functionality polyol can be initiated by an initiator and an alkylene oxide. The initiator can be a polyol or an amine. The initiator can include glycerol, trimethylolpropane, pentaerythritol, sorbitol, sucrose, ammonia, triethanolamine, p-phenylenediamine, ethylenediamine, propylenediamine, butylenediamine, and diethylenetriamine.

[0049] Due to the large number of hydroxyl groups per molecule, high-functionality polyols are highly reactive and produce a highly crosslinked network, which contributes to the high mechanical strength of polyurethane articles, in particular hollow bodies.

[0050] Preferably, the high-functionality polyol is a polyether polyol initiated by an amine. The amine preferably has at least three active hydrogen atoms bonded to nitrogen atoms. Exemplary amines include, but are not limited to, p-phenylenediamine, ethylenediamine, propylenediamine, butylenediamine, and diethylenetriamine. The polyether moiety can be an oxyethylene moiety, an oxypropylene moiety, an oxytetramethylene moiety, or any combination thereof.

[0051] The high-functionality polyol preferably has a content of 10 to 40 wt %, more preferably 15 to 30 wt %, based on the total weight of the polyol component.

[0052] Exemplary high functionality polyols are commercially available from various suppliers, such as BASF. VP 9393, VP 9340, VP 9342, VP 9345, L; Puranol RF TD 400, Puranol RF TD 480, Puranol RF ED 403, Puranol ED 408 purchased from Jiahua; VORAMOL purchased from Dow TM 391. VORAMOL TM 800、VORAMOL TM RA500, VORAMOL TM RA640.

[0053] Bio-derived polyols

[0054] Examples of polyols of biological origin include castor oil, hydrogenated castor oil, soybean oil polyol, palm oil polyol, rosin-based polyols, hydroxy-modified fatty acid esters based on myristoleic acid, palmitoleic acid, oleic acid, vaccenic acid, petroselinic acid, gadoleic acid, erucic acid, nervonic acid, linoleic acid, linolenic acid, stearidonic acid, arachidonic acid, eicosapentaenoic acid, oleic acid and docosahexaenoic acid, and their derivatives. The term "derivatives" includes alkoxylates, transesterification products, ozonolysis / reduction products, ozonolysis / glycolysis products, hydroformylation / reduction products, epoxidation / ring-opening products of carbon-carbon double bonds, or other hydroxyl-containing products of these oils and esters. Preference is given here to using soybean oil polyol, castor oil and their reaction products with alkylene oxides or ketone-formaldehyde resins. Such compounds are known, for example, under the names 750, 805 is available from BASF. As is known in the art, castor oil contains ricinoleic acid triglyceride as its main component, which has hydroxyl groups in the carbon chain. Castor oil-based polyether polyols are obtained by reacting castor oil as a starting material with ethylene oxide and / or propylene oxide. Soybean oil can be converted into polyols through epoxidation, ring-opening reaction, ozone oxidation, transesterification, etc.

[0055] Preferably, the bio-derived polyol has a functionality of 2.0 to 3.5, preferably 2.5 to 3.0. A relatively high functionality will result in a cross-linked network and rigid and elastic articles made from the two-component polyurethane system.

[0056] Preferably, the bio-derived polyol has a content of 20 to 50 wt%, preferably a content of 25 to 45 wt%, more preferably a content of 25 to 40 wt%, based on the total weight of the polyol component.

[0057] Other polyester polyols, polycarbonate polyols and polyether polyols

[0058] In other embodiments, the polyol component provided in the present disclosure may include other polyols. Other polyols include small molecule polyols, polyether polyols, polyester polyols, or polycarbonate polyols.

[0059] Small molecule polyols include, but are not limited to, ethylene glycol, diethylene glycol, dipropylene glycol, glycerol, pentaerythritol, sucrose, and the like.

[0060] Polyester polyols, polycarbonate polyols, and polyether polyols are collectively referred to as polyols. Polyols refer to polyhydroxy compounds. Preferably, polyhydroxy compounds having a functionality of 2 to 8, more preferably 3 to 6, and a hydroxyl value of 150 mg KOH / g to 850 mg KOH / g, more preferably 200 mg KOH / g to 600 mg KOH / g are examples of relatively high molecular weight compounds having at least two reactive hydrogen atoms.

[0061] For example, polythioether polyol, polyesteramide, polyacetal containing hydroxyl group, aliphatic polycarbonate containing hydroxyl group, and preferably polyester polyol and polyether polyol. In addition, a mixture of at least two polyols among the above polyols can be used as long as these polyols have an average hydroxyl value within the above range.

[0062] Suitable polyester polyol can be for example produced by organic dicarboxylic acids with 2 to 12 carbons, preferably aliphatic dicarboxylic acids with 4 to 6 carbons and polyvalent alcohols with 2 to 12 carbons, preferably 2 to 6 carbons, preferably glycols. The example of dicarboxylic acids comprises succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, maleic acid, fumaric acid, phthalic acid, isophthalic acid and terephthalic acid. Dicarboxylic acids can be used individually or with a mixture. Instead of free dicarboxylic acids, corresponding dicarboxylic acid derivatives can also be used, such as dicarboxylic acid monoesters or diesters or dicarboxylic anhydrides with an alcohol of 1 to 4 carbons. The dicarboxylic acid mixture of succinic acid, glutaric acid and adipic acid in the amount ratio of 20-35:35-50:20-32 weight parts is preferred, especially adipic acid. Examples of divalent and polyvalent alcohols, especially diols, include ethylene glycol, diethylene glycol, 1,2- and 1,3-propylene glycol, dipropylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,10-decanediol, glycerol, and trimethylolpropane. Ethylene glycol, diethylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, or a mixture of at least two of these diols is preferred, especially a mixture of 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol.

[0063] Polyester polyols can be produced by polycondensing an organic polycarboxylic acid (e.g., an aromatic or preferably aliphatic polycarboxylic acid and / or its derivatives) with a polyvalent alcohol in the absence of a catalyst or preferably in the presence of an esterification catalyst, preferably in an atmosphere of an inert gas (e.g., nitrogen, carbon dioxide, helium, argon, etc.) in a melt at a temperature of 150° C. to 250° C., preferably 180° C. to 220° C., optionally under reduced pressure, to the desired degree of polymerization (which is preferably less than 10, in particular less than 5). In a preferred embodiment, the esterification mixture is polycondensed at atmospheric pressure and then at a pressure of less than 500 mbar, preferably 50 mbar to 150 mbar, at the above-mentioned temperature to an acid number of 80 to 30, preferably 40 to 30. Examples of suitable esterification catalysts include iron catalysts, cadmium catalysts, cobalt catalysts, lead catalysts, zinc catalysts, antimony catalysts, magnesium catalysts, titanium catalysts, and tin catalysts in the form of metals, metal oxides, or metal salts. However, the polycondensation can also be carried out in the liquid phase in the presence of diluents and / or entrainers, such as benzene, toluene, xylene or chlorobenzene, in order to carry out azeotropic distillation of the condensed water.

[0064] To produce the polyester polyols, preferably the organic polycarboxylic acids and / or their derivatives are polycondensed with the polyvalent alcohols in a molar ratio of 1:1 to 1.8, preferably 1:1.05 to 1.2.

[0065] The resulting polyester polyols preferably have a functionality of 2 to 3 and a hydroxyl number of 150 to 500, and especially 200 to 400.

[0066] Polyether polyols obtainable by known methods can also be used as polyols. For example, polyether polyols can be produced by anionic polymerization using an alkali metal hydroxide (such as sodium hydroxide or potassium hydroxide) or an alkali metal alkoxide (such as sodium methoxide, sodium ethoxide, potassium ethoxide, or potassium isopropoxide) as a catalyst and adding at least one initiator molecule containing 2 to 8, preferably 3 to 8 reactive hydrogen atoms, or by cationic polymerization of one or more alkylene oxides having 2 to 4 carbon atoms in the alkylene radical using a Lewis acid (such as antimony pentachloride, boron trifluoride etherate, etc.) or bleaching earth as a catalyst.

[0067] Suitable cyclic ethers and alkylene oxides include, for example, tetrahydrofuran, 1,3-propylene oxide, 1,2- and 2,3-butylene oxide, styrene oxide, and preferably ethylene oxide and 1,2-propylene oxide. The alkylene cyclic ethers and oxides can be used individually, alternately, one after the other or as a mixture. Examples of suitable initiator molecules include water, polyvalent alcohols, organic dicarboxylic acids (such as succinic acid, adipic acid, phthalic acid, and terephthalic acid), aliphatic and aromatic (optionally N-monosubstituted, N,N-dialkylsubstituted, and N,N′-dialkylsubstituted) diamines having 1 to 4 carbons in the alkyl radical, such as optionally monosubstituted and dialkylsubstituted ethylenediamine, diethylenetriamine, triethylenetetramine, 1,3-propylenediamine, 1,3- and 1,4-butanediamine, 1,2-, 1,3-, 1,4-, 1,5-, and 1,6-hexanediamine, phenylenediamine, 2,3-, 2,4-, and 2,6-toluenediamine, and 4,4′-, 2,4′-, and 2,2′-diaminodiphenylmethane.

[0068] Polyvalent alcohols, especially divalent, trivalent and / or tetravalent alcohols are preferred, such as ethylene glycol, 1,2- and 1,3-propylene glycol, diethylene glycol, dipropylene glycol, 1,4-butanediol, 1,6-hexanediol, glycerol, trimethylolpropane, erythritol, pentaerythritol, sorbitol and sucrose.

[0069] Suitable initiators also include alkanolamines such as ethanolamine, diethanolamine, N-methyl- and N-ethylethanolamine, N-methyl- and N-ethyldiethanolamine, and triethanolamine plus ammonia.

[0070] The polyether polyols have a functionality of preferably 3 to 8 and in particular 3 to 6 and a hydroxyl number of 300 to 850, preferably 350 to 800.

[0071] Also suitable as polyether polyols are melamine polyether polyol dispersions according to U.S. Pat. No. 4,293,657; polymer polyether polyol dispersions prepared from polyepoxides and epoxy resin hardeners in the presence of polyether polyols according to U.S. Pat. No. 4,305,861; dispersions of aromatic polyesters in polyols according to U.S. Pat. No. 4,435,537; dispersions of organic and / or inorganic fillers in polyols according to U.S. Pat. No. 4,243,755; polyurea polyether polyol dispersions according to DE A 312 402, tris-(hydroxyalkyl)isocyanurate polyether polyol dispersions according to U.S. Pat. No. 4,514,526 and particle suspensions according to U.S. Pat. No. 4,560,708, whereby the details of the aforementioned patents are considered part of the present patent disclosure and are incorporated herein by reference.

[0072] Similar to polyester polyols, polyether polyols can be used alone or in the form of a mixture. In addition, they can be mixed with the above-mentioned dispersions, suspensions or polyester polyols and polycarbonate polyols.

[0073] Suitable polycarbonates containing hydroxyl groups include those of known types, such as those obtained by reacting a diol (e.g., 1,3-propylene glycol, 1,4-butanediol and / or 1,6-hexanediol, diethylene glycol, triethylene glycol or tetraethylene glycol) with a diaryl carbonate (e.g., diphenyl carbonate) or phosgene.

[0074] Polyesteramides include predominantly linear condensates obtained from polyvalent saturated and / or unsaturated carboxylic acids and their anhydrides and amino alcohols, or mixtures of polyvalent alcohols and amino alcohols and / or polyamines.

[0075] Chain extenders

[0076] The polyol component includes a chain extender. Chain extenders, as part of the hard segment, are crucial for rotational molding of polyurethane systems. Without being bound by any theory, the formation of hard segments can provide polyurethane with the elasticity and strength required for successful rotational molding of articles, especially hollow articles. Typically, hollow articles are sensitive to applied forces, vibrations, or shocks because their shells can be thin and fragile.

[0077] Preferably, the chain extender is present in an amount of 10 to 20 wt % based on the total weight of the polyol component.

[0078] Suitable chain extenders preferably include diols. Typical examples are aliphatic, cycloaliphatic and / or araliphatic diols having 2 to 14, more preferably 4 to 10 carbon atoms, such as ethylene glycol, 1,3-propylene glycol, 1,10-decanediol, o-, m-, p-dihydroxycyclohexane, diethylene glycol, dipropylene glycol, preferably 1,4-butanediol, 1,6-hexanediol and bis(2-hydroxyethyl)hydroquinone.

[0079] curing agent

[0080] In some preferred embodiments, the polyol component includes a curing agent. The curing agent may include an organic amine having at least two amino groups. The curing agent can accelerate the reaction between the hydroxyl group and the isocyanate group and promote crosslinking. In this type of process, the polymer is toughened and hardened. Based on the gross weight of the polyol component, the content of the curing agent is preferably 0.1 wt % to 2.5 wt %. Adding a curing agent to the curing agent is beneficial because the accelerated reaction will make the mixture become viscous and reduce the demoulding time.

[0081] Exemplary curing agents may be one or more alkanolamines, aromatic diamines, aliphatic diamines, or alicyclic diamines. Specific examples include, but are not limited to, ethanolamine and / or isopropanolamine; dialkanolamines such as diethanolamine, N-methyl-, N-ethyldiethanolamine, diisopropanolamine; trialkanolamines such as triethanolamine, triisopropanolamine; and ethylene oxide or 1,2-propylene oxide with alkylenediamines having 2 to 6 carbon atoms in the alkylene radical (such as N,N'-tetrakis(2-hydroxyethyl)-ethylenediamine and N,N'-tetrakis(2-hydroxypropyl)-ethylenediamine). addition products of 1,3-diaminomethyl-2,6-diaminobenzene; 1,2-, 1,3- or 1,4-diaminohexane; 1,2-, 1,3- or 1,4-diaminomethyl-2,6-diaminobenzene; 1,3-diaminomethyl-2,6-diaminobenzene; 1,3-diaminomethyl-3,6-diaminobenzene; 1,4-diaminomethyl-3 ...4-diaminomethyl-3,6-diaminobenzene; 1,3-diaminomethyl-3,6-diaminobenzene; 1,4-diaminomethyl-3,6-diaminobenzene;

[0082] Viscosity modifiers

[0083] According to the present disclosure, a viscosity modifier is present in the polyol component. The viscosity modifier can be a mixture of a polyol or polymer and a filler. The viscosity modifier adjusts the viscosity of the polyol component and the reaction mixture of the polyol component and the diisocyanate or polyisocyanate component. The viscosity modifier has a viscosity greater than 2,000 mPa s at 25°C; preferably, a viscosity greater than 3,500 mPa s at 25°C; more preferably, a viscosity greater than 5,000 mPa s at 25°C, as measured according to DIN EN 3219. Preferably, the filler content in the viscosity modifier is 20% to 80% by weight, based on the total weight of the viscosity modifier.

[0084] Exemplary viscosity modifiers include GPOP H45, GPOP-36 / 30 from Sinopec Shanghai Gaoqiao Petrochemical Company or CHP-H30, CHP-H45, CHP-H50 from Changhua.

[0085] catalyst

[0086] In order to achieve rapid curing, a catalyst is required in the polyol component of the polyurethane system. The catalyst used in the present disclosure may include one or more amine-based catalysts. The catalyst can greatly accelerate the reaction of the compound containing hydroxyl groups of the component and optionally with polyisocyanates.

[0087] Examples of amine-based catalysts can include amines such as 2,3-dimethyl-3,4,5,6-tetrahydropyrimidine, tertiary amines such as triethylamine, tributylamine, triethylenediamine, 1-methylimidazole, dimethylbenzylamine, N-methylmorpholine, N-ethylmorpholine, N-cyclohexylmorpholine, dimethylpiperazine, 1,2-dimethylimidazole, 1-azabicyclo[3.3.0]octane and preferably 1,4-diaza-bicyclo[2.2.-2]octane, and alkanolamine compounds such as triethanolamine, triisopropanolamine, N-methyl- and N-ethyldiethanolamine, and dimethylethanolamine.

[0088] The metal-based catalyst can include a potassium compound selected from the group consisting of potassium hydroxide, potassium carbonate, potassium bicarbonate, potassium benzoate, potassium formate, potassium acetate, potassium propionate, potassium butyrate, potassium valerate, potassium hexanoate, potassium octoate, potassium 2-ethylhexanoate, potassium neodecanoate, potassium caprate, potassium salicylate, potassium laurate, potassium oleate, potassium maleate, potassium citrate, potassium oxalate, potassium methylate, potassium cellulose, potassium carboxymethyl cellulose, potassium hyaluronate, potassium alginate, potassium gluconate, and any combination thereof. Preferably, the metal-based catalyst does not contain tin, mercury, copper, nickel, or zinc. These metallic elements are generally considered to be harmful to the environment.

[0089] Suitable catalysts include tris-(dialkylamino-s-hexahydrotriazines, especially tris(N,N-dimethylaminopropyl)-s-hexahydrotriazine, tetraalkylammonium hydroxides such as tetramethylammonium hydroxide, alkali metal hydroxides such as sodium hydroxide and alkali metal alcoholates such as sodium methoxide and potassium isopropoxide, and alkali metal salts of long-chain fatty acids having 10 to 20 carbon atoms and optionally OH-dependent groups.

[0090] Rheology modifiers

[0091] To improve the rheological properties of the polyurethane system, one or more rheology modifiers are added to the polyol component. Exemplary rheology modifiers include, but are not limited to, 410, 431, RM 1900, RM 1920, RM 1965, purchased from Bochers Gel Thixo 2.

[0092] Rheology modifiers make the polyurethane system viscous and flowable after being shaken, pressurized, or stirred. The thixotropy of the polyurethane system produces uniformly thin hollow bodies, thus avoiding defects or holes in the surface. It is generally understood that the centrifugal force generated during rotational molding is the driving force for spreading the polymer / reaction mixture on the inner surface of the mold. Rheology modifiers change the rheological behavior of the polymer / reaction mixture and make it flowable when viscous. As a result, uniformly thick layers of molded articles can be achieved without the formation of excessively thick or thin layers, especially at corners or joints, which are prevalent in anatomical models of the human body, torso, or head, or in mannequins for the fashion industry.

[0093] Other additives and auxiliaries

[0094] Optionally, other additives and / or adjuvants may be incorporated into the polyol component to produce the rotational molded article. Examples include moisture scavengers, flame retardants, UV absorbers, surfactants, inorganic fillers, organic fillers, dyes, pigments, odor scavengers, hydrolysis inhibitors, fungistats, bacteriostats, matting agents, antistatic agents.

[0095] Preferably, a moisture scavenger is present in the formulation. The moisture scavenger is able to absorb water and prevent it from reacting with the isocyanate, which would release carbon dioxide, causing the polyurethane system to foam and deteriorating the mechanical strength of the final product.

[0096] Isocyanate component

[0097] The isocyanate component in the present disclosure comprises one or more selected from the group consisting of aliphatic isocyanates, alicyclic isocyanates, araliphatic isocyanates, and aromatic isocyanates. For example, the isocyanate component may comprise an alkylene diisocyanate having 4 to 12 carbons in the alkylene radical, such as 1,12-dodecane diisocyanate, 2-ethyl-1,4-tetramethylene diisocyanate, 2-methyl-1,5-pentamethylene diisocyanate, 1,4-tetramethylene diisocyanate, and preferably 1,6-hexamethylene diisocyanate; an alicyclic diisocyanate, such as 1,3- and 1,4-cyclohexane diisocyanate and any mixtures of these isomers, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (isophorone diisocyanate), 2,4- and 2,6-hexahydromethane Phenyl diisocyanate and the corresponding isomer mixtures, 4,4',2,2'- and 2,4'-dicyclohexylmethane diisocyanate and the corresponding isomer mixtures, and preferably aromatic diisocyanates and polyisocyanates, such as 2,4- and 2,6-toluene diisocyanate (TDI) and the corresponding isomer mixtures, 4,4'-, 2,4'- and 2,2'-diphenylmethane diisocyanate (MDI) and the corresponding isomer mixtures, mixtures of 4,4'- and 2,4'-diphenylmethane diisocyanate and polyphenylenepolymethylene polyisocyanate (polymeric MDI), and mixtures of polymeric MDI and toluene diisocyanate. The organic diisocyanates and polyisocyanates can be used individually or in the form of mixtures.

[0098] Molding process

[0099] The present disclosure also provides a process for preparing articles from a two-component polyurethane system. The process comprises the following steps:

[0100] Providing a two-component polyurethane system according to any one of claims 1 to 9;

[0101] placing the two-component polyurethane system in a hollow mold;

[0102] causing the hollow mold to rotate and the two-component polyurethane system to cure and form an article; and

[0103] Retrieve the product.

[0104] In this process, a two-component polyurethane system as described above is provided.

[0105] The two-component polyurethane system is then placed in a hollow mold. Conventional or specially designed hollow molds known to those skilled in the art can be used.

[0106] The hollow mold with the two-component polyurethane system content is subjected to rotational motion. The rotational motion can be around one or more axes. The rotational motion can generate centrifugal force inside the hollow mold, which then drives the polyurethane system to diffuse and coat the inner surface of the hollow mold. At the same time, the components react and gel. The hollow mold can be heated by an external source or by the exothermic effect of the reaction between the components. During the rotational motion, heating can cause the two-component polyurethane system to solidify and form an article. Preferably, the rotational motion can have a duration of 3 minutes to 30 minutes, more preferably a duration of 5 minutes to 10 minutes. The rotational motion preferably has a rotation speed of 10 revolutions per minute (RPM) to 60RPM.

[0107] After curing is complete, the hollow mold can be opened and the article can be retrieved.

[0108] application

[0109] The present disclosure also provides an article prepared from the above-described two-component polyurethane system. The article is preferably a hollow body, more preferably a mannequin. The article can be used as a mannequin in the fashion industry; as a housing, component, or part in the automotive industry; and as a display model in educational, art, or museum institutions.

[0110] Example

[0111] Measurement and test methods

[0112] The measurement and test methods are shown in Table 1.

[0113] Table 1 Measurement and test standards

[0114] nature unit Test standards Gel time s Annex E of EN 14315-1 Shore hardness D ASTM D2240

[0115] Material

[0116] The materials used in the examples are as follows:

[0117] VP-9345, a polyether polyol with a functionality of 4, an OH value of about 405 mg KOH / g, a molecular weight of about 550 g / mol, and a viscosity of about 12,800 mPa·s (25°C), purchased from BASF;

[0118] 2095, a trifunctional polyether polyol containing primary hydroxyl groups, with an OH value of 35 mg KOH / g; viscosity: about 850 mPa·s (25°C), purchased from BASF;

[0119] Castor oil, commercially available from BASF, has an OH value of 163 mg KOH / g and a functionality of about 2.7. Castor oil is a mixture of triglycerides characterized by containing about 90% by weight of ricinoleic acid triglycerides; viscosity: about 1,025 mPa·s (20° C.);

[0120] 805, a soybean oil-based branched polyether-ester polyol with an OH value of 170 mg KOH / g and a functionality of approximately 3.5; viscosity: approximately 3,400 mPa·s (25°C);

[0121] CHP-H45, a polymer polyol synthesized by free radical graft polymerization with an initiator and monomers of styrene and acrylonitrile, is available from Changhua Chemical in the form of a milky white viscous liquid, has a hydroxyl value of 19 to 23 mg KOH / g, a functionality of 3, and a solids content of 41% to 45%; viscosity: approximately 5,500 to 6,000 mPa·s (25°C);

[0122] Diethylene glycol ("DEG"), a low molecular weight diol used as a chain extender, having a functionality of 2, an OH value of 1057 mgKOH / g, a molecular weight of 106.124 g / mol, and a viscosity of 35.8 mPa·s (20° C.), was purchased from BASF;

[0123] Isocyanate: polymeric methylene diphenyl diisocyanate (MDI), M20 is commercially available from BASF, with a functionality of about 2.7 and an NCO content of 31.5%; viscosity: about 210 mPa·s (25° C.);

[0124] Triethylenediamine, 33-LV tertiary amine catalyst commercially available from Evonik;

[0125] 1-Methylimidazole purchased from BASF;

[0126] Ethacure 100, diethyltoluenediamine available from Albemarle Corporation; and

[0127] T-Paste: Type A zeolite sodium aluminosilicate in oil from UOP, used as a water scavenger.

[0128] Synthesis of polyester polyols

[0129] The raw materials of the polyurethane systems in Examples (Ex. 1 and 2) and Comparative Examples (C.Ex. 1 to 6) were mixed by a VOLLRATHEWTKV 0.5 Lab stirrer and filled into a spherical mold with a diameter of 300 mm by injection. The formulations of the polyurethane systems are given in Table 2.

[0130] The mold is mounted on a conventional rotational molding machine. The mold rotates about two perpendicular axes (axis 1 and axis 2). Axis 1 bisects the mold along one of its diameters. Axis 2 is perpendicular to axis 1. The rotation rate about axis 1 is 15 RPM; the rotation rate about axis 2 is 15 RPM. During rotation, the temperature of the mold initially rises, and the peak temperature exceeds 60°C. Rotation is stopped after the gel time of each example has elapsed. After the rotation is completed, the mold and its contents are kept stationary to allow the mixture to solidify and the strength of the resulting material to develop. The temperature of the mold is slowly lowered. The resulting material is formed into hollow spheres. When the strength is sufficient, the mold is opened and the hollow spheres are removed. The duration from the end of rotation to the removal of the spheres is hereinafter referred to as the "demolding time."

[0131] The hollow spheres were broken into pieces to measure their thickness. The minimum and maximum thickness values were recorded. Successful experiments with rotational molding produced hollow spheres with good mechanical strength and a narrow thickness distribution.

[0132] The process details and test data of the hollow spheres (HB.1 to 8) produced from the polyurethane compositions of the examples and comparative examples are given in Table 3.

[0133] Table 2 Raw materials of polyurethane system

[0134]

[0135] Table 3 Molding parameters and properties of hollow balls

[0136]

[0137]

[0138] Comparative Example 1, which did not include a high-functionality polyol in its formulation, produced soft hollow spheres compared to any of Comparative Examples 2 to 6, Example 1, and Example 2. Thus, it was shown that the high-functionality polyol imparted hardness to the molded article.

[0139] Comparative Example 2, which did not include a chain extender in its formulation, produced brittle hollow spheres compared to any of Comparative Examples 4 to 6, Example 1, and Example 2. Thus, it was shown that the chain extender imparted toughness to the molded article.

[0140] Comparative Example 5, which did not add any rheology modifier, produced hollow spheres with the widest range of thicknesses compared to any other Comparative Example, Example 1, or Example 2. Thus, it was demonstrated that the rheology modifier allowed the reaction mixture to flow when viscous, resulting in a uniformly coated inner surface of the mold.

Claims

1. A two-component polyurethane system for rotational molding, the two-component polyurethane system comprising: A polyol component comprising High-functionality polyols with a functionality greater than 3.5, Bio-derived polyols, Viscosity modifiers, 10 to 20 wt% of a chain extender based on the total weight of the polyol component, Amine catalysts, rheology modifiers; and Diisocyanate or polyisocyanate component.

2. The two-component polyurethane system of claim 1, wherein the high-functionality polyol is a polyether polyol initiated by an amine having at least three active hydrogen atoms bonded to nitrogen atoms.

3. The two-component polyurethane system according to claim 1, wherein the high-functionality polyol has a content of 10% to 40% by weight, preferably 15% to 30% by weight, based on the total weight of the polyol component.

4. The two-component polyurethane system according to claim 1 , wherein the bio-derived polyol comprises at least one member selected from the group consisting of castor oil, hydrogenated castor oil, soybean oil polyol, palm oil polyol, rosin-based polyol, hydroxy-modified fatty acid esters based on myristoleic acid, palmitoleic acid, oleic acid, vaccenic acid, petroselinic acid, gadoleic acid, erucic acid, nervonic acid, linoleic acid, linolenic acid, stearidonic acid, arachidonic acid, eicosapentaenoic acid, oleic acid, and docosahexaenoic acid, and derivatives thereof.

5. The two-component polyurethane system according to claim 1, wherein the bio-derived polyol has a functionality of 2.0 to 3.5, preferably 2.5 to 3.

0.

6. The two-component polyurethane system according to claim 1 , wherein the bio-derived polyol has a content of 20% to 50% by weight, preferably a content of 25% to 45% by weight, more preferably a content of 25% to 40% by weight, based on the total weight of the polyol component.

7. The two-component polyurethane system according to claim 1, wherein the viscosity modifier has a viscosity of greater than 2,000 mPas at 25°C, preferably a viscosity of greater than 3,500 mPas at 25°C, more preferably a viscosity of greater than 5,000 mPas at 25°C, as measured according to DIN EN 3219. 8 . The two-component polyurethane system according to claim 1 , further comprising: a curing agent in an amount of 0.1 wt % to 2.5 wt % based on the total weight of the polyol component. 9 . The two-component polyurethane system according to claim 1 , wherein the isocyanate index of the two-component polyurethane system is in the range of 80 to 120, preferably in the range of 90 to 110.

10. An article produced from the two-component polyurethane system according to any one of claims 1 to 9. The article of claim 10 , wherein the article is a hollow body.

12. The article of claim 10 or 11, wherein the article is a mannequin.

13. A method for producing an article from a two-component polyurethane system according to any one of claims 1 to 9, the method comprising: Providing a two-component polyurethane system according to any one of claims 1 to 9; placing the two-component polyurethane system in a hollow mold; causing the hollow mold to rotate and the two-component polyurethane system to cure and form a product; as well as The article is retrieved.

14. Method according to claim 13, wherein the rotational movement has a duration of 3 to 30 minutes, preferably a duration of 5 to 10 minutes.

15. The method of claim 13, wherein the rotational motion has a rotational speed of 10 to 60 revolutions per minute.

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