TRANSLUCENT POLYURETHANE FOAMS

Abstract

The present invention relates to specific translucent, preferably lightfast, polyurethane foams which have a high light transmission and are therefore suitable e.g. for producing translucent polyurethane foams or multilayer composite elements, for example for producing structural components, more particularly as roof elements such as strip lights and light domes, as wall elements such as a panel, in vehicles, in lamps, as furniture, as partitions and in sanitary facilities.

Claims

1.14. (canceled)

15. A process for producing a translucent polyurethane foam by reacting a component A comprising A1 at least one component reactive with the component B and comprising Zerewitinoff-active hydrogen; A2 water and/or other chemical blowing agents; A3 at least one foam stabilizer; A4 optionally auxiliary and/or additive substances; A5 optionally at least one flame retardant; A6 at least one catalyst; and a component B comprising B1 at least one aliphatic or cycloaliphatic polyisocyanate component and/or a combination thereof, and B2 less than 20 parts by weight of an aromatic poly isocyanate component, wherein the parts by weight of B2 are based on the sum of the parts by weight of B1+B2 which are normalized to 100 parts by weight, wherein the reaction of the component A with the component B is performed at an isocyanate index of 70 to 130 and wherein all parts by weight for components A1 to A6 are normalized such that the parts by weight of A1 to A6 in the composition sum to 100 parts by weight, wherein before onset of the blowing reaction the reaction mixture has a turbidity of less than 3500 NTU measured according to DIN EN ISO 7027:2016-11; and wherein the obtained translucent polyurethane foam has a light transmission according to EN ISO 13468-2:2006 in the range from 10% to 60% measured at a layer thickness of the foam of 20 mm, and wherein the obtained translucent polyurethane foam has a haze (haze=100* diffuse transmission/total transmission) according to ASTM D1003-13 of at least 80% measured at a layer thickness of the foam of 20 mm.

16. The process as claimed in claim 15, wherein the obtained translucent polyurethane foam has a thermal conductivity measured according to DIN 52612:2-1984-06 of less than 100 mW/(m*K).

17. The process as claimed in claim 15, wherein the translucent polyurethane foam is colorless to white and has a yellowing index measured according to ASTM E 313:2015 of less than 10 based on a thickness of the foam of 20 mm.

18. The process as claimed in claim 15, wherein the polyurethane foam is in the form of a polyurethane foam having a closed-cell content of at least 40%.

19. The process as claimed in claim 15, wherein the polyurethane foam moreover has an average cell size between 0.5 mm and 20 mm.

20.

21. The process as claimed in claim 15, wherein the polyurethane foam has an apparent density of the obtained form of not more than 300 kg/m.sup.3, determined according to DIN EN ISO 845:2009-10.

22. The process as claimed in claim 15, wherein the polyurethane foam has an average cell wall thickness of at least 0.05 mm.

23. The process as claimed in claim 15, wherein 65 to 99.2 parts by weight of A1; 0.5 to 8 parts by weight of A2; 0.1 to 5 parts by weight of A3; 0 to 60 parts by weight of A4, are present.

24. The process as claimed in claim 15, wherein 0 to 25 parts by weight of A5; 0.2 to 4 parts by weight of A6 are present.

25. The process as claimed in claim 15, wherein mixing of degassed components take place.

26. A translucent polyurethane foam obtained by a process of claim 15.

27. A multilayer composite element in which the translucent polyurethane foam as claimed in claim 25 is arranged between two dements.

28. The multilayer composite element as claimed in claim 26, wherein the one or the two elements are nonwoven fabrics, non-crimp fabrics, knitted fabrics, films or sheets.

29. A method comprising the translucent polyurethane foam as claimed in claim 25 as a constructional element, as a wall element, in vehicles, in lamps, as furniture, as a dividing wall or in sanitary installations.

Description

EXAMPLES

[0100] In what follows the present invention is more particularly elucidated with reference to examples but is in no way limited thereto:

[0101] Components Used:

[0102] Catalysts [0103] Dibutyltin dilaurate [0104] DBU (1,8-diazabicyclo[5.4.0] undec-7-ene)

[0105] Employed Compounds A): [0106] Desmophen C1100: (difunctional ester carbonate diol having a viscosity of 32001300 mPa*s (at 23 C.), [0107] LS2328: (Difunctional polyester polyol having an OH number of 755 (mg KOH/g)) Foam stabilizers (polyester-polydimethylsiloxane copolymers): [0108] Tegostab B8421

[0109] Employed Isocyanates and Polyisocyanates B) [0110] Desmodur N3900: (iminooxadiazinedione)

[0111] Stabilizers

##STR00001##

[0112] Methods of Measurement Used:

[0113] The coefficients of thermal conductivity were determined according to DIN 52616: 1977-11 using foams having a thickness of 30 mm.

[0114] Light transmission was determined according to EN ISO 13468-2:2006 using foams having a thickness of 20 mm unless a different thickness is explicitly specified.

[0115] Cell size and cell wall thickness were measured as described hereinabove using an optical microscope.

[0116] The yellowing index, also referred to hereinbelow merely as Y1, was determined according to ASTM E 313:2015.

[0117] The turbidity of the reaction mixtures was determined according to DIN EN ISO 7027:2016-11.

Comparative Example 1a and Example 1b

[0118] An isocyanate-reactive composition composed of 65.15 g of Desmophen C1100, 0.17 g of Irganox 1135, 0.17 g of Irganox PS800, 1.75 g of water, 0.13 g of the catalyst dibutyltin dilaurate and 0.25 g of the catalyst DBU was processed with 57.4 g of Desmodur N3900 as described hereinbelow: [0119] a) The abovementioned substances were mixed for 60 seconds at 2800 rpm and a raw material temperature of 23 C. with a Pendraulik laboratory stirrer and the reaction mixture was carefully poured into a mold. The foam had set after 2 h. [0120] b) The abovementioned substances were mixed for 30 seconds at 2750 rpm and a raw material temperature of 23 C. with a Speedmixer and the reaction mixture was carefully poured into a mold. The foam had set after 2 h.

[0121] The following light transmissions were determined according to EN ISO 13468-2 on foams of 20 mm in thickness:

TABLE-US-00001 1a) Pendraulik 1b) Speedmixer 3.4% 17.4% Initial turbidity after Initial turbidity after mixing: 3626 NTU mixing: 388 NTU

Comparative Example 2a and Example 2b

[0122] An isocyanate-reactive composition composed of 48.02 g of LS2328, 0.17 g of Irganox 1135, 1.75 g of water, 0.16 g of foam stabilizer Tegostab 138421 and 0.09 g of catalyst dibutyltin dilaurate, 0.19 g of catalyst DBU was processed with 74.79 g of Desmodur N3900 as described hereinbelow: [0123] c) The abovementioned substances were mixed for 60 seconds at 2800 rpm and a raw material temperature of 23 C. with a Pendraulik laboratory stirrer and the reaction mixture was carefully poured into a mold. The foam had set after 2 h. [0124] d) The abovementioned substances were mixed for 30 seconds at 2750 rpm and a raw material temperature of 23 C. with a Speedmixer and the reaction mixture was carefully poured into a mold. The foam had set after 2 h.

[0125] The following light transmissions were determined according to EN ISO 13468-2 on foams of 15 or 20 mm in thickness:

TABLE-US-00002 2a) Pendraulik 2b) Speedmixer (15 mm)* (20 mm) <2.0% 19.1% Initial turbidity after Initial turbidity after mixing: 4500 NTU mixing: 330 NTU *at a 20 mm thickness of the foam produced by conventional means (Pendraulik stirrer) the light transmission of this fine-celled, white foam was too low and the thickness therefore had to be reduced to 15 mm in order to be able to perform a measurement.

[0126] The thermal conductivity of example 2b measured according to DIN 52616 is 55 mW/mK.

[0127] The Speedmixer DAC 150 FAZ mixing apparatus mixes the components in a largely bubble-free manner while mixing with the laboratory stirrer IKA-RW20 or the laboratory stirrer from Pendraulik brings about incorporation of air. The measured high turbidity of the reaction mixture upon mixing with the Pendraulik IKA-RW20 laboratory stirrer is also apparent from the light transmission of the foams.

[0128] A Pendraulik mixer at 2800 rpm incorporates air into the reaction mixture. An eddy/vortex is formed and a large mixing surface with air is formed during mixing, thus resulting in an undesired introduction of air.

[0129] In a Speedmixer the constituents are mixed in a tumbling rotational motion. As well as effecting low surface area mixing, air, the constituent of lower density, is also expelled from the mixture by the centrifugal force.