Combination foam

Abstract

The combination foam comprises a matrix composed of polyurethane foam and foamed particles of thermoplastic polyurethane comprised therein, where matrix and particles are each made up of polyol components and polyisocyanate components, wherein at least 50% by weight of the basic building blocks forming the polyol component of the matrix and particles are identical and at least 50% by weight of the basic building blocks forming the polyisocyanate component of the matrix and particles are identical.

Claims

1. A combination foam, comprising: a matrix comprising polyurethane foam; and foamed particles of thermoplastic polyurethane comprised therein, wherein the matrix and the particles each comprises polyol components and polyisocyanate components, wherein at least 50% by weight of building blocks forming the polyol component of the matrix and particles are identical and at least 50% by weight of building blocks forming the polyisocyanate component of the matrix and particles are identical, whereby the matrix is completely open-cell and the foamed particles in the matrix are completely closed-cell.

2. The combination foam according to claim 1, wherein at least 60% by weight of the building blocks forming the polyol component of the matrix and particles are identical and at least 60% by weight of the building blocks forming the polyisocyanate component of the matrix and particles are identical.

3. The combination foam according to claim 2, wherein at least 65% by weight of the building blocks forming the polyol component of the matrix and particles are identical and at least 85% by weight of the building blocks forming the polyisocyanate component of the matrix and particles are identical.

4. The combination foam according to claim 1, wherein the foamed particles have a diameter of from 0.1 mm to 10 cm, and are spherical or ellipsoidal.

5. The combination foam according to claim 1, wherein the foamed particles have a density of from 0.005 to 0.50 g/cm.sup.3.

6. The combination foam according to claim 1, wherein the thermoplastic polyurethane of the foamed particles and the polyurethane foam of the matrix comprise polytetrahydrofuran having a number average molecular weight of from 600 to 2500 g/mol.

7. The combination foam according to claim 1, wherein the thermoplastic polyurethane of the foamed particles and the polyurethane foam of the matrix comprise polyester alcohol having a number average molecular weight of from 500 to 2500 g/mol.

8. The combination foam according to claim 1, wherein the matrix is a foam having a density of from 0.03 to 0.8 g/cm.sup.3.

9. The combination foam according to claim 1, wherein the matrix and the particles are present in a weight ratio of from 0.1 to 10:1 in the combination foam.

10. The combination foam according to claim 1, wherein the combination foam is suitable as shoe soles, bicycle saddles, upholstery, in components in automobile interiors and exteriors, in balls and sports equipment or as floor covering.

11. A process for producing the combination foam according to claim 1, comprising reacting the polyol components and polyisocyanate components to form the matrix comprising polyurethane foam and optionally chain extenders, crosslinkers, catalysts, blowing agents, further additives or mixtures thereof, in the presence of the foaming or foamed particles of thermoplastic polyurethane.

12. The process according to claim 11, wherein no external blowing agent is employed.

13. The process according to claim 11, comprising: first preparing an isocyanate prepolymer having an NCO content of from 1 to 20% by weight from polyisocyanate components and polyol components of the matrix; optionally subsequently mixing at least one chain extender, crosslinker, catalyst, further additive or a mixture thereof and the isocyanate prepolymer with the foamed particles of the thermoplastic polyurethane to form a composite; and then curing the composite with water.

Description

EXAMPLES

(1) To determine the mechanical properties of the cured foam plates, four tensile bars having a gauge section width of 25 mm are stamped from each plate. The tensile strength and the elongation at break are determined on these tensile strips by a method based on DIN EN ISO 527-1, using, as a deviation from the standard, a gauge section width of 25 mm and a test velocity of 100 mm/min. The mean was subsequently determined from the results for each single plate.

(2) The following polyurethane systems as shown in Table 1 were examined. Examples 1-3 according to the invention were combined with expanded thermoplastic polyurethane particles (hereinafter referred to as ETPU for short) having a bulk density of 86 g/l. Test plates were produced in a 0.6 l shoe test plate mold heated to 50 C. and these plates were subsequently tested mechanically. The formulation compositions including the proportions of the ETPU in the test specimen are indicated in Table 1. The index, viz. the molar ratio of isocyanate component to polyol component, is 1 with a deviation of less than 0.1 in all systems.

(3) TABLE-US-00001 TABLE 1 Ex. 1 Ex. 2 Ex. 3 Comp. 1 Comp. 2 Comp. 3 Comp. 4 Comp. 5 Polyol 1 46.4 45.3 41.9 31.1 68.4 52.1 28.6 53.3 Polyol 2 5.9 6.2 7.1 10.1 9.5 Polyol 3 10 10.6 12.1 17.2 18.6 9.4 Polyol 4 1.2 Polyol 5 8.6 Iso 1 29.6 29.9 30.5 32.8 25.5 19.4 35.4 30.7 Iso 2 12 CE 5.1 5.1 5 4.5 6.1 4.7 7.3 5.6 Stabi 1.7 1.9 2.2 3 0.7 Cat 1 0.1 0.1 0.2 0.2 Cat 2 0.01 Cat 3 0.95 0.3 Blowing agent 1 0.3 0.3 0.35 0.5 0.06 0.3 Additive 1 0.3 0.3 0.35 0.5 Additive 2 0.4 0.4 0.3 0.05 0.8 0.4 Additive 3 0.4 Additive 4 0.01 % by weight of 41.7 38.5 29.4 100 76.9 ETPU in the total formulation

(4) The meanings of the abbreviations are as follows: ETPU: expanded TPU particles having a bulk density of 86 g/l Polyol 1: polytetrahydrofuran having an average molecular weight (MW) of 1500 g/mol Polyol 2: castor oil having an average molecular weight (MW) of 900 g/mol Polyol 3: polypropylene glycol having an average molecular weight (MW) of 2000 g/mol Polyol 4: polypropylene glycol having an average molecular weight (MW) of 200 g/mol Polyol 5: acrylonitrile/styrene-comprising polypropylene glycol having an average molecular weight (MW) of 4400 g/mol Iso 1 diphenylmethane 4,4-diisocyanate partly carbodiimide-modified and having a total NCO content of 33.6 parts by mass Iso 2 aliphatic polyisocyanate based on isocyanuratized hexamethylene diisocyanate and having a proportion by mass of NCO of 22 parts CE chain extender, diol having a hydroxyl number of greater than 580 mg/g Stabi polyether-siloxane copolymers Cat 1 1-methylimidazole Cat 2 dimethyltin carboxylate Cat 3 catalyst mixture based on tertiary amines, triethylenediamine, triethanolamine and dimethylamino ether Blowing agent 1 water Additive 1 sulfated castor oil, sodium salt in, on a fatty acid ester basis, 50% of water Additive 2 antioxidant, sterically hindered phenol derivative Additive 3 KCaNaAl silicate in castor oil Additive 4 polydimethylsiloxane

EXAMPLES

(5) The production and properties of the polyurethane systems are described in the following examples. In examples 1, 2 and 3 and comparative examples 1 and 4, a prepolymer having a total isocyanate content of 18 parts by mass and comprising the reaction products of a partly carbodiimide-modified diphenylmethane 4,4-diisocyanate with a polypropylene glycol having an average molecular weight (MW) of 1970 g/mol and tripropylene glycol and also a UV stabilizer was used. These individual prepolymer constituents are shown in their proportions in table 1. Corresponding to the processing, this prereaction product is referred to as prepolymer in the following examples.

(6) Furthermore, the ETPU particles comprising 61.2 parts by mass of polytetrahydrofuran having an average molecular weight (MW) of 1000 g/mol, 31.8 parts by mass of diphenylmethane 4,4-diisocyanate having a total NCO content of 33.6 parts by mass, 6 parts by mass of 1,4-butanediol having a hydroxyl number of 1245 mg/g and also 0.1 part by mass of UV stabilizer corresponding to their total proportion as shown in Table 1 were produced. They were produced in a manner analogous to WO 2008/087078, pages 23/24. They were processed in fully reacted, expanded forms. The products according to the invention were produced in the laboratory using a blender.

Example 1 (According to the Invention)

(7) In accordance with table 1, the constituents with the exception of the prepolymer and the ETPU particles were weighed in together and homogenized. This A component was heated to 50 C. in an oven. This was followed by the addition of prepolymer at room temperature and intensive mixing for 10 seconds. These components were poured into a second vessel into which the ETPU particles had been weighed beforehand. Immediately afterward, the particles in the second vessel were mixed with the PU system for 30 s. This particle/binder mixture was subsequently introduced into a metal test plate mold heated to 50 C. and left in the mold until curing was complete. Test specimens on which the mechanical tests were carried out were cut from the test plates produced in this way.

Example 2 (According to the Invention)

(8) The test specimens were produced and tested as in example 1. The constituents were varied corresponding to the column example 2 shown in table 1.

Example 3

(9) The test specimens were produced and tested as in example 1. The constituents were varied corresponding to the column for example 3 shown in table 1.

Comparative Example 1 (Without ETPU)

(10) In accordance with table 1, the constituents with the exception of the prepolymer were weighed in together and homogenized. This A component was heated to 50 C. in an oven. This was followed by the addition of prepolymer at room temperature and intensive mixing for 10 seconds. Immediately afterward the system was introduced into a metal test plate mold heated to 50 C. and left in the mold until curing was complete. Test specimens on which the mechanical tests were carried out were cut from the test plates produced in this way. Comparative example 1 corresponds to the matrix formulation of example 3, with the resulting density having been matched to example 1.

Comparative Example 2

(11) The ETPU particles were introduced into a metal mold suitable for steam fusion. Steam was subsequently introduced, as a result of which the ETPU particles sintered together. Test specimens on which the mechanical tests were carried out were cut from the test plates produced in this way.

Comparative Example 3

(12) In accordance with table 1, the constituents with the exception of the isocyanate component 3 and the ETPU particles were weighed in together and homogenized. This was followed by addition of the isocyanate and intensive mixing for 10 seconds. All components were processed unheated at a room temperature of 22 C. The components were poured into a second vessel into which the ETPU particles had been weighed beforehand. Immediately afterward, the particles were introduced into the second vessel with the PU system for 30 s, leveled uniformly and left in the mold until curing was complete. Test specimens on which the mechanical tests were carried out were cut from the test plates produced in this way.

Comparative Example 4

(13) In accordance with table 1, the constituents with the exception of the prepolymer were weighed in together and homogenized. This A component was heated to 50 C. in an oven. This was followed by addition of the prepolymer at room temperature and intensive mixing for 10 seconds. Directly afterward, the system was introduced into a metal test plate mold heated to 50 C. and left in the mold until curing was complete. Test specimens on which the mechanical tests were carried out were cut from the test plates produced in this way.

Comparative Example 5

(14) In accordance with table 1, the constituents with the exception of the prepolymer were weighed in together and homogenized. This A component was heated to 50 C. in an oven. This was followed by addition of the prepolymer at room temperature and intensive mixing for 10 seconds. Immediately afterward, the system was introduced into a metal test plate mold heated to 50 C. and left in the mold until curing was complete. Test specimens on which the mechanical tests were carried out were cut from the test plates produced in this way.

(15) Properties of the Products Obtained

(16) TABLE-US-00002 TABLE 2 Ex. 3 Comp. 1 Comp. 2 Comp. 5 Density 290 310 300 300 Tensile strength 2816 1087 700 1400 Elongation at break 190 126 100 n. d. Density overall density of the test plate [kg/m.sup.3] Tensile strength tensile strength [kPa] in accordance with DIN EN ISO 527-1 Elongation at break elongation at break [%] in accordance with DIN EN ISO 527-1 n. d. not determined

(17) It can be seen from table 2 that the examples according to the invention in the same low density range of 300 g/l+/10 g/l display a higher tensile strength than comparable systems. The elongation at break values are likewise better in the case of the samples according to the invention.

(18) TABLE-US-00003 TABLE 3 Ex. 1 Ex. 2 Comp. 3 Comp. 4 Density 215 270 175 275 Tensile strength 1793 3047 264 2400 Rebound 53 52 53 33 Density overall density of the test plate [kg/m.sup.3] Tensile strength tensile strength [kPa] in accordance with DIN EN ISO 527-1 Rebound rebound resilience [%] in accordance with DIN EN ISO 8307

(19) Table 3 shows that the examples according to the invention have better tensile strengths and rebound resiliences even at lower densities. No testable specimens in this low density range could be produced from comparative examples 1, 2 and 5.