Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G18/00—Polymeric products of isocyanates or isothiocyanates
  • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
  • C08G18/70—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the isocyanates or isothiocyanates used
  • C08G18/72—Polyisocyanates or polyisothiocyanates
  • C08G18/74—Polyisocyanates or polyisothiocyanates cyclic
  • C08G18/76—Polyisocyanates or polyisothiocyanates cyclic aromatic
  • C08G18/7657—Polyisocyanates or polyisothiocyanates cyclic aromatic containing two or more aromatic rings
  • C08G18/7664—Polyisocyanates or polyisothiocyanates cyclic aromatic containing two or more aromatic rings containing alkylene polyphenyl groups
  • C08G18/7671—Polyisocyanates or polyisothiocyanates cyclic aromatic containing two or more aromatic rings containing alkylene polyphenyl groups containing only one alkylene bisphenyl group
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
  • C08J9/04—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent
  • C08J9/12—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent by a physical blowing agent
  • C08J9/122—Hydrogen, oxygen, CO2, nitrogen or noble gases
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G18/00—Polymeric products of isocyanates or isothiocyanates
  • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
  • C08G18/08—Processes
  • C08G18/10—Prepolymer processes involving reaction of isocyanates or isothiocyanates with compounds having active hydrogen in a first reaction step
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G18/00—Polymeric products of isocyanates or isothiocyanates
  • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
  • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
  • C08G18/40—High-molecular-weight compounds
  • C08G18/42—Polycondensates having carboxylic or carbonic ester groups in the main chain
  • C08G18/4202—Two or more polyesters of different physical or chemical nature
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G18/00—Polymeric products of isocyanates or isothiocyanates
  • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
  • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
  • C08G18/65—Low-molecular-weight compounds having active hydrogen with high-molecular-weight compounds having active hydrogen
  • C08G18/66—Compounds of groups C08G18/42, C08G18/48, or C08G18/52
  • C08G18/6603—Compounds of groups C08G18/42, C08G18/48, or C08G18/52 with compounds of group C08G18/32 or polyamines of C08G18/38
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G18/00—Polymeric products of isocyanates or isothiocyanates
  • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
  • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
  • C08G18/65—Low-molecular-weight compounds having active hydrogen with high-molecular-weight compounds having active hydrogen
  • C08G18/66—Compounds of groups C08G18/42, C08G18/48, or C08G18/52
  • C08G18/6666—Compounds of group C08G18/48 or C08G18/52
  • C08G18/667—Compounds of group C08G18/48 or C08G18/52 with compounds of group C08G18/32 or polyamines of C08G18/38
  • C08G18/6674—Compounds of group C08G18/48 or C08G18/52 with compounds of group C08G18/32 or polyamines of C08G18/38 with compounds of group C08G18/3203
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
  • C08J9/36—After-treatment
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G2110/00—Foam properties
  • C08G2110/0008—Foam properties flexible
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G2110/00—Foam properties
  • C08G2110/0083—Foam properties prepared using water as the sole blowing agent
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2201/00—Foams characterised by the foaming process
  • C08J2201/02—Foams characterised by the foaming process characterised by mechanical pre- or post-treatments
  • C08J2201/022—Foams characterised by the foaming process characterised by mechanical pre- or post-treatments premixing or pre-blending a part of the components of a foamable composition, e.g. premixing the polyol with the blowing agent, surfactant and catalyst and only adding the isocyanate at the time of foaming
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2375/00—Characterised by the use of polyureas or polyurethanes; Derivatives of such polymers
  • C08J2375/04—Polyurethanes

Definitions

• the present invention relates to the field of polyurethane elastomer foaming technology, in particular to a process of preparing a polyurethane elastomer foam and a product thereof.
• PU polyurethane
• foaming technology to form a large number of pores inside the polyurethane (PU) material, thus forming a polyurethane foam material with a porous structure, is an effective means to obtain lightweight products and save materials.
• the presence of a large number of pores can also endow the material with excellent performances such as thermal insulating, damping and cushioning, noise-reducing and sound-absorbing.
• Conventional polyurethane foaming mainly includes three processes of: (1) a prepolymer process, in which a polyol (white material) and an isocyanate (black material) are first mixed and made into a prepolymer, then blowing agent, catalyst(s), surfactant(s), and other additive(s), etc.
• a semiprepolymer process in which a polyol (a white material) and an isocyanate (a black material) are first mixed and made into a prepolymer, then another polyether or polyester polyol and isocyanate, water, a catalyst, a surfactant, other additive(s), etc.
• the supercritical fluid when a physical blowing agent such as supercritical N2 or CO2 is used, the supercritical fluid is dissolved within the polymer matrix, the fluid reaches a supersaturated state after a rapid increase in temperature, and after pressure-releasing, it induces pore nucleation, promotes pore growth, and realizes foaming of the polymer materials.
• Solid-state foaming can control the pore size by controlling the temperature, and is suitable for the production of polymer foam materials with special pore diameters such as microcellular foam.
• CN105829417A discloses a process for production of expanded thermoplastic elastomer beads, comprising an impregnating step, an expanding step and optionally a fusing step, the produced thermoplastic elastomer beads have an uninterrupted skin, a low density and a uniform pore distribution, and bead expansion and shaped-part production are possible in one operation and in one apparatus.
• CN 110126171 A discloses an integrated foam molding process for polymer particles, comprising steps of: 1) preparing polymer particles with a high-melting point macromolecule resin coated by a low-melting point macromolecule resin; 2) subjecting the polymer particles to one-step foam molding to obtain a foamed product.
• the foaming temperature is below the melting point of the core resin, so that foamed beads can be formed at the core of the particles.
• the foaming temperature is higher than the melting point of the shell resin, the surface is in a molten state.
• the shell resin in the molten state enables the particles to be fused together.
• the particles are in a fluidized state during foaming, the temperatures of all the particles are consistent, the particles are ensured not to be bonded in advance, the internal fusing is uniform and consistent when expansion occurs, filling defects are avoided.
• thermoplastic elastomers such as thermoplastic polyurethane elastomers (TPU).
• TPU thermoplastic polyurethane elastomers
• this process usually requires a step of making the thermoplastic polyurethane elastomer into particles by an extruder or by other processes before foam molding.
• the overall process requires many steps and is complex.
• the present invention provides a polyurethane foaming process, which overcomes the technical problems existing in the above prior art and produces a low-density polyurethane foam product with good physical properties, while the process is simple and efficient.
• the invention provides a process of preparing a polyurethane elastomer foam, comprising the steps of: a) premixing a polyol with an optional additive to obtain a mixed component A; b) mixing and adding an isocyanate-containing component B and component A into a mold, and closing the mold for reaction to obtain a polyurethane preform; c) placing the polyurethane preform in a closed cavity, introducing a fluid into the closed cavity until the closed cavity reaches pressure P, at the same time raising the temperature to a first temperature T1, allowing the fluid that has reached a supercritical or near-supercritical state in the cavity to impregnate the polyurethane preform, wherein temperature T1 is in a range of from 80 °C to 190 °C, preferably from 90 °C to 160 °C, pressure P is in a range of from 5 MPa to 50 MPa, and the impregnation time is from 3 minutes to 6 hours; and d) releasing the pressure of the closed
• the polyol in component A of the above step a) may be a polyether polyol, a polyester polyol, or a mixture thereof.
• the polyether polyols used for preparing polyurethanes are obtained by known methods, for example by anionic polymerization of alkylene oxides with addition of at least one starter molecule that contains 2 to 8, preferably 2 to 6 reactive hydrogen atoms in bonded form, in the presence of a catalyst.
• a catalyst alkali metal hydroxides, such as sodium hydroxide or potassium hydroxide, or alkali metal alkoxides, such as sodium methoxide, sodium ethoxide, potassium ethoxide or potassium isopropoxide, may be used; or in the case of cationic polymerization, Lewis acids, such as antimony pentachloride, boron trifluoride etherate or bleaching earth may be used as a catalyst.
• double metal cyanide compound which is called DMC catalyst, may also be used as a catalyst.
• alkylene oxides preference is given to using one or more compounds having 2 to 4 carbon atoms in the alkylene radical, such as ethylene oxide, 1,2-propylene oxide, tetrahydrofuran, 1,2- or 2,3-butylene oxide, in each case alone or in the form of mixtures, and preferably ethylene oxide and/or 1,2-propylene oxide.
• Possible starter molecules are, for example, ethylene glycol (MEG), diethylene glycol, glycerol, trimethylolpropane (TMP), pentaerythritol, sugar derivatives, such as sucrose, sugar alcohols, such as sorbitol, methylamine, ethylamine, isopropylamine, butylamine, aniline, toluidine, toluenediamine, naphthylamine, ethylenediamine, diethylenetriamine, 4,4’- methylenedianiline, 1,3-propanediamine, 1,6-hexanediamine, ethanolamine, diethanolamine, triethanolamine, and other di- or polyhydric alcohols or mono- or polyfunctional amines.
• MEG ethylene glycol
• TMP trimethylolpropane
• pentaerythritol sugar derivatives, such as sucrose
• sugar alcohols such as sorbitol
• the polyether polyol further comprises polytetrahydrofuran.
• the polyester polyols are usually prepared by condensation of polyols having 2 to 12 carbon atoms, such as ethylene glycol, diethylene glycol, butanediol (BDO), trimethylolpropane, glycerol or pentaerythritol, with polycarboxylic acids having 2 to 12 carbon atoms, such as succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, maleic acid, fumaric acid, phthalic acid, isophthalic acid, terephthalic acid, and the isomers of naphthalinedicarboxylic acids, or the anhydrides thereof.
• the polycarboxylic acids also include other sources of dicarboxylic acids, such as dimethyl terephthalate (DMT), polyethylene terephthalate (PET), and the like.
• the polyols used in the present invention further include bio-based polyether and polyester polyols, including but not limited to polyether polyols made from castor oil, palm oil, olive oil, soybean oil, etc.; polyether polyols starting from algae, lignin, etc.; and polyester polyols starting from bio-based dibasic acids such as sebacic acid, succinic acid, bio-based polyols such as ethylene glycol, butylene glycol, propylene glycol.
• bio-based polyether and polyester polyols including but not limited to polyether polyols made from castor oil, palm oil, olive oil, soybean oil, etc.; polyether polyols starting from algae, lignin, etc.; and polyester polyols starting from bio-based dibasic acids such as sebacic acid, succinic acid, bio-based polyols such as ethylene glycol, butylene glycol, propylene glycol.
• polyether polyols or polyester polyols used in the present invention have a hydroxyl value in a range of from about 20 to about 270 mg KOH/g, preferably from about 28 to about 200 mg KOH/g, more preferably from about 28 to about 150 mg KOH/g, even more preferably from about 28 to about 100 mg KOH/g, most preferably from about 28 to about 80 mg KOH/g.
• the polyether polyols or polyester polyols have a molecular weight in a range of from about 500 to about 10,000, preferably from about 600 to about 6,000, more preferably from about 1 ,000 to about 2,500. Furthermore, the polyether polyols or polyester polyols have a polydispersity index in a specific range, such as in a range of from about 0.8 to about 1.3, preferably from about 0.9 to about 1.2, more preferably from about 0.95 to about 1.1.
• Component A may further comprise a crosslinker and/or a chain extender.
• crosslinkers and/or chain extenders amines or alcohols having two or more functionalities, or mixtures thereof, are used, in particular, for example bifunctional or trifunctional amines and alcohols, in particular diols, triols or mixtures thereof, are used, in each case having a molecular weight of less than 350, preferably from 60 to 300 and in particular from 60 to 250.
• the bifunctional compounds are called chain extenders and trifunctional or higher-functional compounds are called crosslinkers.
• aliphatic, cycloaliphatic and/or aromatic diols having from 2 to 14, preferably from 2 to 10, carbon atoms, e.g., ethylene glycol, 1 ,2-propanediol, 1 ,3-propanediol, 1,2-pentanediol, 1,3-pentanediol, 1,10- decanediol, 1,2-dihydroxycyclohexane, 1 ,3-dihydroxycyclohexane, 1,4-dihydroxycyclohexane, diethylene glycol and triethylene glycol, dipropylene glycol and tripropylene glycol, 1,4- butanediol, 1,6-hexanediol and bis(2-hydroxyethyl)hydroquinone; triols such as 1,2,4- trihydroxycyclohexane, 1,3,5-trihydroxycyclohexane, glycerol and trimethyl
• the chain extender may be an individual compound or a mixture.
• the chain extender preferably comprises propylene glycol, dipropylene glycol, tripropylene glycol and/or 2,3- butanediol, either alone or optionally in admixture with one another or with further chain extenders.
• crosslinker preference is given to 1,2,4-trihydroxycyclohexane, 1 ,3,5- trihydroxycyclohexane, glycerol and/or trimethylolpropane, either alone or optionally in admixture with one another.
• the reaction of forming polyurethane is carried out in the presence of a catalyst, and the catalyst may be optionally added to component A or component B as desired.
• catalysts it is possible to use all compounds which prompt the isocyanate-polyol reaction. Such compounds are known and are described, for example, in “Kunststoff handbuch, Volume 7, Pll”, Carl Hanser - Verlag, 3 rd edition, 1993, chapter 3.4.1. These include amine- based catalysts and catalysts based on organic metal compounds.
• 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 dialkyltin(IV) salts of organic carboxylic acids, such as dibutyltin diacetate, dibutyltin dilaurate, dibutyltin maleate and dioctyltin diacetate; and also bismuth(lll) carboxylates, bismuth 2-ethylhexanoate and bismuth octoate, or alkali metal salts of carboxylic acids, e.g., potassium acetate or potassium formate.
• organic tin compounds such as tin(ll) salts of organic carboxylic acids, e.g., tin(ll) acetate, tin(ll) oc
• amine-based catalysts it is possible to use bis(2-dimethylaminoethyl) ether, N,N,N’,N”,N”-pentamethyldiethylenetriamine, 2-(2-diethylaminoethoxy)ethanol, dimethylcyclohexylamine, dimethylbenzylamine, triethylamine, triethylenediamine, pentamethyldipropylenetriamine, dimethylethanolamine, N-methylimidazole, N-ethylimidazole, tetramethylhexamethylenediamine, tris(dimethylaminopropyl)hexahydrotriazine, dimethylaminopropylamine, N-ethylmorpholine, diazabicycloundecene and diazabicyclononene.
• component A of the present invention those skilled in the art can also add any auxiliary and/or additive as desired, including but not limited to pore regulators, fillers, pigments, dyes, antioxidants, hydrolytic stabilizers, antistatic agents, fungicides and bacteriostatic agents, etc.
• the isocyanate-containing component B in step b) of the present invention comprises diisocyanates or polyisocyanates, which may be selected from any aliphatic, cycloaliphatic or aromatic isocyanates known to be useful for preparing polyurethanes, including but not limited to diphenylmethane 2,2’-, 2,4’- and 4,4’-diisocyanate, the mixtures of monomeric diphenylmethane diisocyanates (MDI) and diphenylmethane diisocyanate homologs having a greater number of rings (polymeric MDI), isophorone diisocyanate (IPDI) or its oligomers, tolylene diisocyanate (TDI), such as tolylene diisocyanate isomers such as tolylene 2,4- or 2,6- diisocyanate, or a mixture of these, tetramethylene diisocyanate or its oligomers, hexamethylene diisocyanate (HDI
• the diisocyanates or polyisocyanates used preferably comprise isocyanates based on diphenylmethane diisocyanate, in particular comprise polymeric MDI.
• the functionality of the diisocyanates or polyisocyanates is preferably in a range of from 2.0 to 2.9, particularly preferably from 2.1 to 2.8.
• the diisocyanates and polyisocyanates can also be used in the form of prepolymers. These prepolymers are obtainable by reacting excessive diisocyanates and/or polyisocyanates as described above with compounds having at least two groups reactive toward isocyanates, for example at a temperature in a range of from 30 to 100 °C, preferably 80 °C, to give the prepolymer.
• the NCO content of the diisocyanate prepolymer and/or the polyisocyanate prepolymer of the present invention is preferably in a range of from 10 to 33% by weight of NCO, particularly preferably in a range of from 15 to 28% by weight of NCO.
• neither component A nor component B comprises an additional blowing agent.
• the polyurethane preform may be molded by injection or casting.
• the mixture of component A and component B may be added into the mold by injection or casting.
• the polyurethane preform used in the present invention is directly molded after liquid mixing. The processing technology is more flexible and simpler, and the production efficiency is higher.
• the polyurethane preform obtained in step b) has a hardness of not greater than 80 Shore A, preferably in a range of from 10 to 80 Shore A, more preferably from 20 to 80 Shore A, further preferably from 45 to 75 Shore A.
• the preferred closed cavity is a pressure vessel resistant to high temperature and high pressure, such as an autoclave reactor.
• the required pressure and the necessary temperature are dependent on the used polyurethane preform, the used auxiliary material, the used fluid, and the mixing ratio between the components.
• any fluid known to those skilled in the art can be used for impregnation, preferably an inert gas such as argon, nitrogen or carbon dioxide, particularly preferably carbon dioxide or nitrogen or a mixture thereof.
• an inert gas such as argon, nitrogen or carbon dioxide, particularly preferably carbon dioxide or nitrogen or a mixture thereof.
• the fluid used as blowing agent is particularly preferably a mixture of CCh and N2.
• any mixing ratio of CO2 to N2 is usable.
• a mixed blowing agent including 50 % to 100 % by weight of carbon dioxide and 0 % to 50 % by weight of nitrogen.
• the blowing agent comprises only CO2, N2 or a mixture of these two gases, with no other blowing agent.
• a mixed blowing agent comprising 50 to 100 wt % of nitrogen and 0 to 50 wt % of carbon dioxide.
• step c) of the present invention the temperature is set in a range of from 80 °C to 190 °C, and the pressure P is set in a range of from 5 MPa to 50 MPa, allowing the fluid that has reached a supercritical or near-supercritical state in the cavity to impregnate the polyurethane preform.
• the impregnation of the fluid to the polyurethane preform can reach saturation.
• Impregnation saturation refers to impregnation in a high-pressure fluid atmosphere until the high-pressure fluid and the polyurethane preform reach a dissolution equilibrium.
• the impregnation time is usually in a range of from 3 minutes to 6 hours.
• pressure P is set in a range of from 10 MPa to 18 MPa, and the impregnation time is in a range of from 3 minutes to 2 hours, preferably in a range of from 30 minutes to 90 minutes.
• the preform is foam-molded by releasing the pressure, and the pressure-releasing rate is in a range of from 3 MPa/s to 500 MPa/s.
• the rate is in a range of from 4 MPa/s to 100 MPa/s, more preferably from 5 MPa/s to 30 MPa/s.
• the process further comprises step e) of cooling at a temperature in a range of from 0 to 25 °C.
• the polyurethane elastomer foam material obtained in step d) or e) is placed in a mold for further hot pressing.
• the polyurethane elastomer foam material obtained in step d) or e) is further cut into the desired size.
• the foaming of the polyurethane preform in step d) is partial, which means that the pressure at the first temperature T1 is reduced to a pressure that is that is higher than ambient pressure, and the density of the partially foamed polyurethane preform is greater than the density of the polyurethane elastomer foam material that can be obtained by reducing the pressure to ambient pressure.
• the partially foamed polyurethane preform is subsequently fully expanded at second temperature T2, for which purpose the pressure at the second temperature T2 is reduced until a desired density is obtained.
• the desired density is more preferably obtained when the pressure at the second temperature T2 is reduced to ambient pressure.
• Foaming step d2) can be carried out in the same device or in another device than the one for foaming step d).
• foaming by supercritical fluid is a method in which a fluid is injected into a closed cavity loaded with a polyurethane preform material, and is brought into a supercritical or near-supercritical state after reaching a certain temperature and pressure, wherein the obtained system is maintained at this state for a certain period of time, such that the supercritical/near-supercritical fluid penetrates into the polyurethane preform to form a polymer/fluid homogeneous system, and the equilibrium state of the polymer/fluid homogeneous system inside the material is destroyed by reducing the pressure at a certain rate, thereby forming bubble nuclei inside the material, then the bubble nuclei grows and takes a shape to obtain a foamed material; wherein increasing the pressure can improve the solubility of the fluid in the polymer, and then the number of bubble nuclei increases, and the pore density increases; with the increase in pressure drop, the rate of bubble nucleation increases, and more bubble nuclei are formed; the fluid concentration gradient inside and outside the
• the final product can meet the requirement of lightweight, and the density can be in a range of from 0.05 g/cm 3 to 0.50 g/cm 3 , preferably from 0.10 g/cm 3 to 0.35 g/cm 3 .
• the processed foam may have a hardness in a range of from 10 to 70 Asker C, preferably from 10 to 65 Asker C, more preferably from 10 to 50 Asker C, still more preferably from 20 to 45 Asker C.
• the present invention also provides the use of polyurethane elastomer foams.
• the polyurethane elastomer foam is used in the field of transportation, furniture, sports products or shoe materials.
• the polyurethane elastomer foam is used for seat.
• the polyurethane elastomer foam is used for sole.
• the polyurethane elastomer preform is made into a foamed material through a supercritical fluid foam-molding process.
• the obtained foamed material has better physical properties than the polyurethane foam foamed with a chemical blowing agent under the same density.
• It can be used in the field of transportation, such as vehicle seats, car interiors, armrests, etc., and in the field of furniture, such as cushioning materials, various cushion laminate composite materials, and can also be used as soundinsulation materials, filter materials, decorative materials, shockproof materials, packaging materials and thermal-insulation materials, etc., and it can also be used in the application fields of sports products, shoe materials, etc., such as helmets, protective gears, soles, insoles, sports auxiliary equipment and the like.
• the shoes are endowed with a lighter weight, high resilience and excellent physical properties, which can give the shoe wearer a better comfort experience; at the same time, compared with the process wherein thermoplastic polyurethane is firstly granulated and then foamed, the process of the present invention is much simpler, requires milder conditions and a shorter production line, achieves a high efficiency, and also is green and environmentally friendly, and suitable for large-scale industrial production.
• orientation or positional relationship indicated by the terms “center”, “upper”, “lower”, “left”, “right”, “vertical”, “horizontal”, “inside”, “outside”, etc. is based on the orientation or positional relationship, the terms are only used for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the indicated device or element must have a specific orientation, or must be constructed and operated according to a specific orientation, and therefore shall not be construed as having any limitation on the present invention.
• the terms “first”, “second”, and “third” are used for descriptive purposes only and shall not be construed to indicate or imply the relative importance.
• connection may be a fixed connection or a detachable connection, or an integrated connection; it may be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal communication between two elements.
• connection may be a fixed connection or a detachable connection, or an integrated connection; it may be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal communication between two elements.
• test methods used in the present invention are as follows:
• the polyols are as follows: Table 2
• the amine-based catalyst is Dabco EG, purchased from Evonik.
• the tin-based catalyst is Fomrez UL-28, purchased from Huntsman.
• the silicone oil is Dabco DC 193, purchased from Evonik.
• Example 1 The silicone oil is Dabco DC 193, purchased from Evonik.
• Component B Isocyanate Prepolymer 1
• Component A and component B were fully mixed with the ratio of 100: 52 by weight percentage, then poured into a mold, and demolded after 10 minutes of reaction to obtain a non-foamed polyurethane preform having a hardness of 55 Shore A.
• the obtained polyurethane preform was placed in a closed cavity, to this closed cavity carbon dioxide gas was introduced until 10 MPa was reached, and the temperature was elevated to 120 °C at the same time, allowing the supercritical carbon dioxide in the cavity to impregnate the polyurethane preform for an impregnation time of 60 minutes. After reaching the impregnation time, the pressure was released for expanding and foam molding, giving a polyurethane foam material, wherein the pressure-releasing rate was 10 MPa/s.
• Component B Isocyanate Prepolymer 1
• Component A and component B were fully mixed in the ratio of 100: 83.1 by weight, then poured into a mold, and demolded after 10 minutes of reaction to obtain a polyurethane foam material.
• Component B Isocyanate Prepolymer 2
• Component A and component B were fully mixed in the ratio of 100: 37.7 by weight, then poured into a mold, and demolded after 10 minutes of reaction to obtain a non-foamed polyurethane preform having a hardness of 63 Shore A.
• the obtained polyurethane preform was placed in a closed cavity, to the closed cavity carbon dioxide gas was introduced until 12 MPa was reached, and the temperature was elevated to 140 °C at the same time, allowing the supercritical carbon dioxide in the cavity to impregnate the polyurethane preform for an impregnation time of 60 minutes. After reaching the impregnation time, the pressure was released for expanding and foam molding, giving a polyurethane foam material, wherein the pressure-releasing rate was 10 MPa/s.
• Component B Isocyanate Prepolymer 2
• Component A and component B were fully mixed in the ratio of 100: 80.1 by weight, then poured into a mold, and demolded after 10 minutes of reaction to obtain a polyurethane foam material.
• Component B Isocyanate Prepolymer 3
• Component A and component B were fully mixed in the ratio of 100: 52.8 by weight, then poured into a mold, and demolded after 15 minutes of reaction to obtain a non-foamed polyurethane preform having a hardness of 80 Shore A.
• the obtained polyurethane preform was placed in a closed cavity, to the closed cavity carbon dioxide gas was introduced until 12 MPa was reached, and the temperature was elevated to 140 °C at the same time, allowing the supercritical carbon dioxide in the cavity to impregnate the polyurethane preform for an impregnation time of 60 minutes. After reaching the impregnation time, the pressure was released for expanding and foam molding, giving a polyurethane foam material, wherein the pressure-releasing rate was 10 MPa/s.
• Component B Isocyanate Prepolymer 3
• Component A and component B were fully mixed in the ratio of 100: 91.5 by weight, then poured into a mold, and demolded after 15 minutes of reaction to obtain a polyurethane foam material.
• Table 11
• Component B Isocyanate Prepolymer 4
• Component A and component B were fully mixed in the ratio of 100: 45 by weight, then poured into a mold, and demolded after 10 minutes of reaction to obtain a non-foamed polyurethane preform having a hardness of 25 Shore A.
• the obtained polyurethane preform was placed in a closed cavity, to the closed cavity carbon dioxide gas was introduced until 10 MPa was reached, and the temperature was elevated to 120 °C at the same time, allowing the supercritical carbon dioxide in the cavity to impregnate the polyurethane preform for an impregnation time of 60 minutes. After reaching the impregnation time, the pressure was released for expanding and foam molding, giving a polyurethane foam material, wherein the pressure-releasing rate was 10 MPa/s.
• Component B Isocyanate Prepolymer 4
• Component A and component B were fully mixed in the ratio of 100:100 by weight, then poured into a mold, and demolded after 10 minutes of reaction to obtain a polyurethane foam material.
• Component B Isocyanate Prepolymer 5
• Component A and component B were fully mixed in the ratio of 100: 50 by weight, then poured into a mold, and demolded after 15 minutes of reaction to obtain a non-foamed polyurethane preform having a hardness of 90 Shore A.
• the obtained polyurethane preform was placed in a closed cavity, to the closed cavity carbon dioxide gas was introduced until 12 MPa was reached, and the temperature was elevated to 140 °C at the same time, allowing the supercritical carbon dioxide in the cavity to impregnate the polyurethane preform for an impregnation time of 60 minutes. After reaching the impregnation time, the pressure was released for expanding and foam molding, giving a polyurethane foam material, wherein the pressure-releasing rate was 10 MPa/s.
• each of the polyurethane preforms in Examples 1 to 4 has a hardness of below 80, and the foams obtained after foaming have uniform pores and relatively stable production.
• the hardness of the preform in Comparative Example 5 exceeds Shore A 80, the foaming performance is poor, the pores are not uniform, and the production is also unstable.

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• 2022
  • 2022-08-17 EP EP22765840.8A patent/EP4392471A1/en active Pending
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