EXPANDED THERMOPLASTIC POLYURETHANE BEADS, PRODUCTION THEREOF AND PRODUCTION OF A MOLDED PART

Abstract

Disclosed herein are expanded thermoplastic polyurethane beads polymerized from an isocyanate, an isocyanate-reactive compound having a molecular weight between 500 and 10 000 g/mol and a chain extender, wherein customary adjuvants may be additionally present, and the thermoplastic polyurethane has a hard phase fraction ranging from 0.1 to 0.95 and the hard phase fraction is defined by:

[00001]$\mathrm{Hard}.Math..Math.\mathrm{phase}.Math..Math.\mathrm{fraction}=\frac{\underset{x=1}{\overset{k}{.Math.}}.Math.\left(\left(\frac{m_{\mathrm{KVx}}}{M_{{\mathrm{KV}}_x}}\right).Math.M_{\mathrm{Iso}}+m_{\mathrm{KVx}}\right)}{m_{\mathrm{ges}}}$

where M.sub.KVx represents a molar mass of chain extender x in g/mol, m.sub.KVx represents a mass of chain extender x in g, M.sub.Ixo represents a molar mass of isocyanate in g/mol, m.sub.ges represents a total mass of all starting materials without adjuvants, and k represents a number of chain extenders. Also disclosed herein are processes for producing expanded thermoplastic polyurethanes and processes for producing molded parts therefrom.

Claims

1-14. (canceled)

15: Expanded thermoplastic polyurethane beads polymerized from an isocyanate, an isocyanate-reactive compound having a molecular weight between 500 and 10 000 g/mol and a chain extender, wherein: customary adjuvants may be additionally present; the thermoplastic polyurethane has a hard phase fraction in the range from 0.1 to 0.95 and the hard phase fraction is defined by: $\mathrm{Hard}.Math..Math.\mathrm{phase}.Math..Math.\mathrm{fraction}=\frac{\underset{x=1}{\overset{k}{.Math.}}.Math.\left(\left(\frac{m_{\mathrm{KVx}}}{M_{{\mathrm{KV}}_x}}\right).Math.M_{\mathrm{Iso}}+m_{\mathrm{KVx}}\right)}{m_{\mathrm{ges}}},$ where: M.sub.KVx: molar mass of chain extender x in g/mol, M.sub.KVx: mass of chain extender x in g, M.sub.Ixo: molar mass of isocyanate in g/mol m.sub.ges: total mass of all starting materials without adjuvants k: number of chain extenders; the chain extender is a diol having 5 to 10 carbon atoms, a mixture of two or more diols with one or more than one diol has 4 to 10 carbon atoms and all further diols have 2 to 10 carbon atoms, a mixture of one or more than one diol having 4 to 10 carbon atoms and one or more than one diamine, or a mixture of one or more than one diol having 4 to 10 carbon atoms and an aminoalcohol.

16: The expanded thermoplastic polyurethane according to claim 15, wherein the isocyanate is selected from the group consisting of trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, heptamethylene diisocyanate, octamethylene diisocyanate; 2-methylpentamethylene 1,5-diisocyanate, 2-ethylbutylene 1,4-diisocyanate, butylene 1,4-diisocyanate, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane; 1,4-bis(isocyanatomethyl)cyclohexane; 1,4-cyclohexane diisocyanate, 1-methyl-2,4-cyclohexane diisocyanate, 1-methyl-2,6-cyclohexane diisocyanate; 2,2-dicyclohexylmethane diisocyanate; 2,4-dicyclohexylmethane diisocyanate; 4,4-dicyclohexylmethane diisocyanate; 2,2-diphenylmethane diisocyanate; 2,4-diphenylmethane diisocyanate; 4,4-diphenylmethane diisocyanate; 1,5-naphthylene diisocyanate; 2,4-tolylene diisocyanate; 2,6-tolylene diisocyanate; diphenylmethane diisocyanate; 3,3-dimethylbiphenyl diisocyanate; 1,2-diphenylethane diisocyanate and phenylene diisocyanate and also any desired mixture thereof.

17: The expanded thermoplastic polyurethane according to claim 15, wherein the isocyanate-reactive compound is selected from the group consisting of a polyetherol, a polyesterol, a polybutadienol, a polycarbonateol, mixtures thereof, and block copolymers thereof.

18: The expanded thermoplastic polyurethane according to claim 15, wherein: only one chain extender is present in the polymerization; and the chain extender is selected from the group consisting of 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,4-cyclo hexyldimethanol, 2-butyl-2-ethylpropanediol, neopentyl glycol, 2,2,4-trimethyl-1,3-pentane diol, pinacol, 2-ethyl-1,3-hexanediol, 1,4-cyclohexanediol and N-phenyldiethanol amine.

19: The expanded thermoplastic polyurethane according to claim 15, wherein, when a mixture of two or more diols is used, the diol having 4 to 10 carbon atoms comprises from 0.001 to 50 wt % based on total chain extender mass.

20: The expanded thermoplastic polyurethane according to claim 19, wherein: a first diol of the mixture of two or more diols is selected from the group consisting of 1,4-butanediol and 1,6-hexanediol and all further diols are selected from 1,2-ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,4-cyclohexyldimethanol, 2-butyl-2-ethylpropanediol, neopentyl glycol, 2,2,4-trimethyl-1,3-pentanediol, pinacol, 2-ethyl-1,3-hexanediol, 1,4-cyclohexanediol and N-phenyldiethanolamine; and the first diol is different from all further diols in the mixture of two or more diols.

21: The expanded thermoplastic polyurethane according to claim 15, wherein the expanded thermoplastic polyurethane is closed cell and has a cell size in the range from 1 to 250 m.

22: The expanded thermoplastic polyurethane according to claim 15, wherein the expanded thermoplastic polyurethane is in the form of beads having a maximum longitudinal dimension of 1 to 25 mm.

23: A process for producing an expanded thermoplastic polyurethane according to claim 15, the process comprising: (a) reacting an isocyanate with an isocyanate-reactive compound and a chain extender optionally in the presence of one or more catalysts and/or adjuvants to form a polyurethane, wherein: amounts of isocyanate, of isocyanate-reactive compound and of chain extender are adjusted such that the thermoplastic polyurethane has a hard phase fraction in the range from 0.1 to 0.95 and the hard phase fraction is defined by: $\mathrm{Hard}.Math..Math.\mathrm{phase}.Math..Math.\mathrm{fraction}=\frac{\underset{x=1}{\overset{k}{.Math.}}.Math.\left(\left(\frac{m_{\mathrm{KVx}}}{M_{{\mathrm{KV}}_x}}\right).Math.M_{\mathrm{Iso}}+m_{\mathrm{KVx}}\right)}{m_{\mathrm{ges}}},$ where M.sub.KVx: molar mass of chain extender x in g/mol, m.sub.KVx: mass of chain extender x in g, M.sub.Ixo: molar mass of isocyanate in g/mol m.sub.ges: total mass of all starting materials without adjuvants k: number of chain extenders; the chain extender is a diol having 5 to 10 carbon atoms, a mixture of two or more diols with one or more than one diol has 4 to 10 carbon atoms and all further diols have 2 to 10 carbon atoms, a mixture of one or more than one diol having 4 to 10 carbon atoms and one or more than one diamine, or a mixture of one or more than one diol having 4 to 10 carbon atoms and an aminoalcohol; (b) cutting the polyurethane into pellets; (c) impregnating the polyurethane with a blowing agent, wherein impregnating can be carried out before or after cutting the polyurethane into pellets; and (d) depressurizing the blowing agent-impregnated polyurethane into the expanded thermoplastic polyurethane.

24: The process according to claim 23, wherein the polyurethane is impregnated with the blowing agent in an extruder, the impregnated polyurethane is cut into a pellet material, and the pellet material is depressurized into expanded thermoplastic polyurethane beads immediately after cutting.

25: The process according to claim 23, wherein the polymerizing of the polyurethane in step (a) is carried out in a first extruder or a first extruder part, the impregnating of the melt is carried out in a second extruder or a second extruder part, the impregnated polyurethane is cut into a pellet material, and the pellet material is depressurized into expanded thermoplastic polyurethane beads immediately after cutting.

26: The process according to claim 23, wherein the polyurethane polymerized in step (a) is cut into a pellet material, the pellet material is impregnated with from 0.1 to 40% by weight of a blowing agent in a tank or in an autoclave at a temperature in the range from 100 to 180 C. and a pressure in the range from 5 to 100 bar, and then the blowing agent-containing pellet material is foamed by depressurization.

27: A process for producing a molded part from the expanded thermoplastic polyurethane beads according to claim 15, the process comprising: (a) introducing the expanded thermoplastic polyurethane beads into a mold; and (b) subjecting the expanded thermoplastic polyurethane beads introduced into the mold to steam, hot air or high-energy radiation whereby the expanded thermoplastic polyurethane beads incipiently melt at the surface and fuse together to form the molded part.

28: The process according to claim 27 wherein the molded part is a shoe sole, a gymnastics mat, a body protector, a trim element in automotive construction, a sound absorber, a vibration absorber, a cushioning pad, a bicycle saddle, a toy, a tire or a tire part or a surface for an athletic running track, a sports hall or a footpath, a damping layer or a damping core in a sandwich element or a packaging item.

Description

[0102] The plate surfaces facing the moving side of the mold are depicted in the Figures, where

[0103] FIG. 1 shows a surface image of the plate obtained in Example 1,

[0104] FIG. 2 shows a surface image of the plate obtained in Example 3,

[0105] FIG. 3 shows a surface image of the plate obtained in Example 4,

[0106] FIG. 4 shows a surface image of the plate obtained in Comparative Example 3,

[0107] FIG. 5 shows a surface image of the plate obtained in Comparative Example 4,

[0108] FIG. 6 shows a surface image of the plate obtained in Comparative Example 6.

[0109] It can be clearly seen that for comparable starting material Shore hardnesses listed in Table 2, satisfactory surfaces, where the bead structure is also still discernible, are only obtained for the plate obtained as per Comparative Example 6 as well as those obtained as per the inventive examples. The plates obtained according to Comparative Examples 3 and 4 end up with a smooth surface, pointing to a plastic deformation of the surface texture of the plate.

TABLE-US-00004 TABLE 4 Steam overpressures and times to fuse together the materials of the inventive and comparative examples Gap Gap Cross steam Cross steam Cross steam Cross steam Autoclave steam Autoclave steaming steaming fixed side fixed side moving side moving side fixed/moving side steam (bar) (s) (bar) (s) (bar) (s) (bar) (s) Ex. 1 0.75 10 1.2 20 Ex. 2 0.75 10 1.2 20 Ex. 3 1.6 10 1.6 10 1.0/1.0 15 Ex. 4 1.3 40 1.3/0.8 10 Comp. Ex. 1 1.3 18 1.8 30 Comp. Ex. 2 0.4 5 2.2 40 2.2 40 Comp. Ex. 3 0.7 30 2.2 7 2.6 7 1.9/1.9 32 Comp. Ex. 4 1.9 7 1.9 7 1.9/1.9 32 Comp. Ex. 5 1.1 15 1.3 30 Comp. Ex. 6 1.9 10 2 20 Comp. Ex. 7 fusion not possible at 3 bar

TABLE-US-00005 TABLE 5 Steam temperatures (measured at mold) and times to fuse together the materials of the inventive and comparative examples Gap Gap Cross steam Cross steam Cross steam Cross steam Autoclave steam Autoclave steaming steaming fixed side fixed side moving side moving side fixed/moving side steam ( C.) (s) ( C.) (s) ( C.) (s) ( C.) (s) Ex. 1 116 10 123 20 Ex. 2 116 10 123 20 Ex. 3 128 10 128 10 120/120 15 Ex. 4 124 40 124/116 10 Comp. Ex. 1 124 18 131 30 Comp. Ex. 2 109 5 135 40 135 40 Comp. Ex. 3 115 30 135 7 139 7 132/132 32 Comp. Ex. 4 132 7 132 7 132/132 32 Comp. Ex. 5 121 15 124 30 Comp. Ex. 6 132 10 133 20 Comp. Ex. 7 fusion not possible at 143 C.

[0110] Fusion quality of the plates can be determined via the tear strength (DIN ISO 34-1, test specimens 10050 mm with 50 mm incision). The higher the tear strength, the better the fusion with starting materials of identical Shore hardness. The values of the inventive and comparative examples are listed in Table 6.

TABLE-US-00006 TABLE 6 Results on tear strength of fused plates in inventive and comparative examples (plate thickness 20 mm) Plate density Tear strength (kg/m.sup.3) (N/mm) Ex. 1 236 4 0.11 Ex. 2 232 3.58 0.28 Ex. 3 208 3.9 0.3 Ex. 4 226 2.58 0.1 Comp. Ex. 1 287 3.96 0.17 Comp. Ex. 2 292 3.45 0.10 Comp. Ex. 3 327 3.5 0.2 Comp. Ex. 4 299 0.59 0.1 Comp. Ex. 5 272 1.88 0.59 Comp. Ex. 6 263 1.57 0.27

[0111] The samples can also be tested for tensile strength as an alternative to tear strength. Tensile strength was determined for a plate thickness of 10 mm in accordance with ASTM D5035:2015 standard designed for textiles, and the values are listed in Table 7.

TABLE-US-00007 TABLE 7 Results on tensile testing of fused plates in inventive and comparative examples (plate thickness 10 mm) Plate density Tensile strength Breaking extension (kg/m.sup.3) (kPa) (%) Ex. 1 270 1460 90 169 17 Ex. 2 235 911 38 119 3 Ex. 3 240 820 20 104 10 Ex. 4 230 850 6 71 13 Comp. Ex. 1 301 812 73 95 14 Comp. Ex. 2 305 919 83 120 17 Comp. Ex. 3 310 819 20 83 4 Comp. Ex. 4 314 730 70 53 8 Comp. Ex. 5 281 450 9 53 11 Comp. Ex. 6 291 710 6 89 10

Production of the Expanded Pellets by Impregnation in an Autoclave

[0112] For the Examples 5 and 6 as well as the Comparative Examples 8 and 9 the Example Materials 2 and 3 or rather the Reference Materials 2 and 3 were further processed as described below.

[0113] The experiments were performed with a tank fill level of 80% and a phase ratio of 0.39. The phase ratio is defined as the ratio of the mass of pellet material to the suspension medium, water in the examples.

[0114] 100 parts by weight of the pellet material (corresponding to 28.0 wt %, based on the entire suspension without blowing agent), 257 parts by weight of water (corresponding to 72.0% wt %, based on the entire suspension without blowing agent), 0.13 parts by weight of a surface-active substance (Lutensol AT 25) (corresponding to 0.04 wt %, based on the entire suspension without blowing agent) and the corresponding quantity of butane as blowing agent (based on the quantity of pellets used) were heated with stirring. At a temperature of 50 C., in the liquid phase, nitrogen was then additionally injected, and the internal pressure was adjusted to a pressure of 800 kPa. On reaching the impregnation temperature, and where applicable after compliance with a retention time, and at the impregnation pressure reached at the end, depressurization was then carried out by way of a depressurization device.

[0115] Retention time is defined as the time at which the temperature of the liquid phase is in a temperature range of 5 C. below the impregnation temperature and 2 C. above the impregnation temperature.

[0116] After drying the bulk density of the resultant foam beads is measured.

[0117] The exact production parameters and the bulk density of the resultant product can be found in Table 8.

TABLE-US-00008 TABLE 8 Data on the examples and the comparative examples Proportion of Impregnation Retention Impregnation Particle Bulk blowing agent temperature time pressure mass density Material used [%] [ C.] [min] [bar] [mg] [kg/m.sup.3] Ex. 5 Ex. Mat. 2 24 122 23 26.0 32 105 Ex. 6 Ex. Mat. 3 24 127 30 29.3 32 72 Comp. Ex. 8 Ref. Mat. 2 24 128 3 30.4 32 131 Comp. Ex. 9 Ref. Mat. 3 24 135 3 34.7 32 142

[0118] The expanded pellets were subsequently fused together on a Boost Foamer molding machine from Kurtz ersa GmbH by steaming to form square plates having an edge length of 200 mm and a thickness of 10 mm. The fusion parameters of the different materials were chosen such that the final molded part's plate side facing the moving side of the mold displayed as few collapsed ETPU beads as possible. Gap steaming was also effected where applicable via the moving side of the mold. A satisfactory surface finish was not always attainable in the comparative examples. The different temperatures and steaming times for the examples and comparative examples were necessary to produce comparable plates. Under identical conditions the particles of the comparative examples either were not fused together homogeneously or had collapsed on the surface. Irrespective of the run, a cooling time of 120 s was always established at the end from the fixed and moving sides of the mold. The particular steaming conditions are listed as steam pressures in Table 9 and as corresponding steam temperatures in Table 10. It is apparent that a lower maximum steam pressure is needed to fuse together the polyurethane beads of the inventive example versus those of the comparative examples.

TABLE-US-00009 TABLE 9 Steam overpressures and times to fuse together the materials of the inventive and comparative examples Gap Gap Cross steam Cross steam Cross steam Cross steam Autoclave steam Autoclave steaming steaming fixed side fixed side moving side moving side fixed/moving side steam (bar) (s) (bar) (s) (bar) (s) (bar) (s) Ex. 5 1 20 1.9 4 1.9 7 1.9/1.9 32 Ex. 6 1 20 2.5 10 2.5 13 2.5/2.5 32 Comp. Ex. 8 1 20 2.4 3 2.4 3 2.4/2.4 48 Comp. Ex. 9 1 20 3.2 3 3.2 3 3.2/3.2 48

TABLE-US-00010 TABLE 10 Steam temperatures (measured at mold) and times to fuse together the materials of the inventive and comparative examples Gap Gap Cross steam Cross steam Cross steam Cross steam Autoclave steam Autoclave steaming steaming fixed side fixed side moving side moving side fixed/moving side steam ( C.) (s) ( C.) (s) ( C.) (s) ( C.) (s) Ex. 5 120 20 132 4 132 7 132/132 32 Ex. 6 120 20 138 10 138 13 138/138 32 Comp. Ex. 8 120 20 137 3 137 3 137/137 48 Comp. Ex. 9 120 20 144 3 144 3 144/144 48

[0119] In order to determine fusion quality the tensile strength of the samples was tested. Tensile strength was determined for a plate thickness of 10 mm in accordance with ASTM D5035:2015 standard designed for textiles, and the values are listed in Table 11.

TABLE-US-00011 TABLE 11 Results on tensile testing of fused plates in inventive and comparative examples (plate thickness 10 mm) Plate density Tensile strength Breaking extension (kg/m.sup.3) (kPa) (%) Ex. 5 203 580 10 65 7 Ex. 6 147 530 70 53 9 Comp. Ex. 8 307 587 100 74 15 Comp. Ex. 9 240 503 80 58 13