MULTILAYER STRUCTURE, PRODUCTION AND USE THEREOF

Abstract

The invention relates to a multilayer structure comprising at least three layers and to a method for the production and use thereof.

Claims

1. A multilayer system made of at least three layers with the following layer sequence: (i) a first exterior layer (1), (ii) a middle core layer made of a rigid polyurethane foam with a thermal conductivity of 24 mW/m*K in accordance with DIN 52616 at 24 C. and (iii) a second exterior hydrolysis-resistant polyurethane layer (2), wherein the polyurethane of the second exterior layer (2) can be produced from the reaction of the following components: a polyol component consisting of: a) at least one polyol selected from the group consisting of a polyether polyol, a polyester polyol and a mixture thereof respectively with a number-average molar mass from 1000 to 12 000 g/mol and a number-average functionality of at least 2, b) at least one glycolic chain extender having two hydroxy groups per molecule and a molar mass from 62 to 499 g/mol, c) at least one polyether polyol with a number-average functionality from 3 to 6 and a number-average molar mass from 200 to 900 g/mol, (d) at least one catalyst, e) at least one inorganic white pigment which is dispersible in the polyol a), f) at least one triazole-class UV absorber which is soluble or dispersible in the polyol a), g) optionally auxiliary and/or additional substances, and an isocyanate component consisting of: h) an NCO prepolymer with at most 28% by weight NCO content, based on at least one polyisocyanate selected from the group consisting of methylenediphenyl 4,4-diisocyanate (MDI), 2,2-MDI, 2,4-MDI, higher homologs of these, mixtures thereof, 4,4-diisocyanatodicyclohexylmethane (HMDI), 2,2-HMDI, 2,4-HMDI, higher homologs of these and mixtures thereof, and at least one polyol selected from the group consisting of polyether polyol, polyester polyol and mixtures thereof respectively with a number-average molar mass from 150 to 12 000 g/mol and with a number-average functionality of at least 2, wherein, based on the entirety of components a), b), c), d) and h), the quantities used of the polyol a) are from 25 to 50% by weight, the quantities used of the chain extenders b) are from 6 to 14% by weight, the quantities used of the polyether polyol c) are from 2 to 10% by weight, the quantities used of the catalyst d) are from 0.05 to 0.5% by weight, the quantities used of the inorganic white pigment e) are from 0.1 to 5% by weight, the quantities used of the UV absorbers f) are from 0.1 to 5% by weight, and the ratio of the NCO groups in the isocyanate component to the OH groups in the polyol component is from 0.9:1 to 1.2:1, and wherein the TVOC (total volatile organic components) content of the polyurethane is below 3000 g T/Nm.sup.3 in accordance with DIN EN ISO 16000-9 after storage for 24 h at room temperature with air change rate 0.5 m.sup.3/h, temperature 23 C. and relative humidity 50%, and a E of the polyurethane is smaller than 13 after irradiation for 500 h in accordance with DIN ISO 16474-2, part 2 xenon arc lamps, in accordance with method B (xenon arc lamp with window glass filters, intensity of irradiation 50 W/m.sup.2 at from 300 to 400 nm, sample space temperature 38 C., black standard temperature 65 C. and relative humidity 50%), and the polyurethane of the middle core layer can be produced from the reaction of the following components: A) at least one polyol selected from the group consisting of polyether polyols, polyester polyols and polyester polyether polyols B) aromatic polyisocyanates C) physical blowing agents D) water E) optionally catalysts, F) optionally auxiliary and/or additional substances, wherein the polyurethane of the middle core layer is not chemically the same as the polyurethane of the second exterior layer (2).

2. A process for the production of the multilayer system as claimed in claim 1, which has at least three layers, wherein 1) the second exterior layer (2) is produced by means of RIM processes (reaction injection molding) from the mixture of components a) to h) within a reaction time 5 sec., 2) the second exterior layer (2) and the first exterior layer (1) are inserted into a foaming mold in a manner such that a cavity is formed between the two layers, 3) the cavity from step 2) is then foam-filled with the reaction mixture made of components A) to F) for the rigid polyurethane foam in a manner such that the middle core layer is formed, and 4) the product from step 3) is removed from the foaming mold.

3. A method of using the multilayer system as claimed in claim 1 comprising producing a product selected from the group consisting of automobile parts or commercial-vehicle parts, household equipment, housings, frame parts and containers.

Description

EXAMPLES

[0067] Starting Components for the Second Exterior Layer (2): [0068] a) Polyols:

[0069] Polyol 1:

[0070] Polyether polyol, OH number 28, obtainable via addition of propylene oxide and ethylene oxide (in a ratio of 80:20) onto trimethylolpropane as starter having 90% of primary OH groups. Functionality: 3; Molar mass: 6000 g/mol;

[0071] Polyol 2:

[0072] Polyether polyol, OH number 35, obtainable via addition of propylene oxide and ethylene oxide (in a ratio of 80:20) onto trimethylolpropane as starter having 90% of primary OH groups. Functionality: 3, Molar mass: 4800 g/mol; [0073] b) Ethylene glycol [0074] c) Polyether polyol, OH number 550, functionality 3, molar mass 305 g/mol [0075] d) Catalysts: Dabco T9 (tin octanoate) [0076] Fomrez UL32 (dioctyltin mercaptide) [0077] Dabco DMEA (dimethylethanolamine) [0078] e) Titanium-dioxide-based white pastes: White Remap 10007 (about 50% by weight of TiO.sub.2) Moltopren MP61005/1322 (about 60% by weight of TiO.sub.2) [0079] f) UV absorber: Tinuvin B75; mixture of antioxidant (Irganox 1135) and hindered amines (Tinuvin 765) and UV absorber (Tinuvin 571; 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methylphenol) [0080] Tinuvin 622; hindered amine (poly(N-beta-hydroxyethyl-2,2,6,6-tetramethyl-4-hydroxypiperidyl succinate)) [0081] Milestab 234-PD (triazole); 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol [0082] h) Prepolymer:

[0083] Prepolymer (PREP) with 23% NCO content, obtainable from 86.15% of 4,4-diisocyanatodiphenylmethane having 33.5% NCO content and 13.85% of tripropylene glycol

[0084] Table 1 describes the components and quantities thereof for the production of the polyurethane of the second exterior layer (2).

TABLE-US-00001 TABLE 1 Example 1 Example 2 Example 3 Example 4 (of the invention) (comparative example) (comparative example) (comparative example) Components [% by weight] [% by weight] [% by weight] [% by weight] Polyol 1 31.7 75.53 38.92 38.92 Polyol 2 31.7 0.00 38.92 38.92 Ethylene glycol 17.9 19.15 18.79 18.79 Polyether polyol c) 8.2 Moltopren-MP-61005/1322 3.19 3.22 3.22 White Remap 10007 6.1 Milestab 234-PD 4.1 Tinuvin B75 1.60 Tinuvin 622: Not dispersible and not soluble Dabco T9 0.27 Dabco DMEA 0.27 Fomrez UL32 0.26 0.16 0.16 Prepolymer PREP 127.3 138.52 140.14 140.14

TABLE-US-00002 TABLE 1 E after UV irradiation in accordance with DIN ISO 16474-2, Method B E after 250 h E after 500 h Example 1 8.1 10.5 (of the invention) Example 2 23.0 (comparative example) Example 3 42.1 (comparative example) Example 4 Not measurable (comparative example) HIPS* 9.4 *HIPSHigh-impact polystyrene

[0085] Example 1 of the invention exhibited very little discoloring after 500 h of UV irradiation.

TABLE-US-00003 TABLE 3 Total migration in accordance with EU 10/2011, Annex V, Chapter 3, Table 3, test no. OM1; triple determination Residue Residue Residue Solvent [mg/dm.sup.2] [mg/dm.sup.2] [mg/dm.sup.2] 3% by weight of acetic acid 2.0 2.3 2.0 10% by volume of ethanol 2.0 1.6 1.6

[0086] Total migration values measured on the second exterior layer (2) of the invention in testing in accordance with Regulation (EU) No. 10/2011 Annex V, Chapter 3, Table 3, Test no. OM1 in 3% by weight acetic acid and 10% by volume of ethanol were smaller than 10 mg/dm.sup.2.

[0087] The values for E (UV resistance) and for total migration are dependent only on the second exterior layer (2), and these values were therefore determined directly on the second exterior layer (2).

[0088] The combination of this second exterior layer (2) with a core layer made of conventional rigid polyurethane foam and an exterior layer gives a three-layer composite with good adhesion and with good mechanical stability, and with thermal conductivity <24 mW/m*K in accordance with DIN 52616 at 24 C., resulting from the rigid polyurethane foam layer.