Polyol Component for the Production of PUR Foams

Abstract

A composition comprising (a1) a polyether polyol, (a2) a polyolefine polyol and (a3) a polyester polyol obtainable by epoxidation of an unsaturated fatty acid ester and subsequent ring-opening reaction with a compound containing active hydrogen, can be used for the preparation of PUR foam which distinguishes by low-temperature flexibility and low dielectric loss and is suitable for filling the gap between the condenser core and the outer composite or porcelain insulator in the manufacture of resin impregnated paper (RIP) bushings.

Claims

1. A process for producing a polyurethane foam by reacting a polyol component with a polyisocyanate, in the presence of a blowing agent, wherein the polyol component comprises based on the weight of the composition, (a) a polyether polyol, (b) 30-70% by weight of a polyolefin polyol, and (c) a polyester polyol obtained by epoxidation of an unsaturated fatty acid ester and subsequent ring-opening reaction with a compound containing active hydrogen.

2. A process for manufacturing resin impregnated paper (RIP) bushings comprising: providing a condenser core, providing an outer composite insulator, and filling the gap between the condenser core and the outer composite insulator with a polyurethane foam prepared according to the process of claim 1.

3. An insulating material for pipes comprising a polyurethane foam prepared according to the process of claim 1.

4. A hollow core composite insulator comprising a polyurethane foam prepared according to the process of claim 1 in the space in the hollow core tube.

5. A process for producing a polyurethane foam by reacting a polyol component with a polyisocyanate, in the presence of a blowing agent, wherein the polyol component comprises, (a) a polyether polyol, (b) a polyolefin polyol, (c) a polyester polyol obtained by epoxidation of an unsaturated fatty acid ester and subsequent ring-opening reaction with a compound containing active hydrogen, and (d) a polysiloxane-polyoxyalkylene block copolymer wherein the polyolefin polyol comprises at least one of the compounds represented by formulas (1) and (2), and wherein x, y, z, v and w represent the percentages of the structural units and denote the following ranges: x=10 to 70%, y=15 to 70%, z=10 to 30%, v=10-75%, w=25-90%, with the proviso x+y+z=100% and v+w=100%.

6. A process for manufacturing resin impregnated paper (RIP) bushings comprising: providing a condenser core, providing an outer composite insulator, and filling the gap between the condenser core and the outer composite insulator with a polyurethane foam prepared according to the process of claim 5.

7. An insulating material for pipes comprising a polyurethane foam prepared according to the process of claim 5.

8. A hollow core composite insulator comprising a polyurethane foam prepared according to the process of claim 5 in the space in the hollow core tube.

9. A process for producing a polyurethane foam by reacting a polyol component with a polyisocyanate, in the presence of a blowing agent, wherein the polyol component comprises, (a1) 5-30% by weight of a polyether polyol, (a2) 35-65% by weight of a polyolefin polyol, (a3) 10-50% by weight of a polyester polyol obtained by epoxidation of an unsaturated fatty acid ester and subsequent ring-opening reaction with a compound containing active hydrogen, and (a4) a polysiloxane-polyoxyalkylene block copolymer wherein the polyolefin polyol comprises at least one of the compounds represented by formulas (1) and (2): wherein x, y, z, v and w represent the percentages of the structural units and denote the following ranges: x=10 to 70%, y=15 to 70%, z=10 to 30%, v=10-75%, w=25-90%, with the proviso x+y+z=100% and v+w=100% and (B) a polyisocyanate comprising polymeric methylene-diphenyldiisocyanate.

10. A process for manufacturing resin impregnated paper (RIP) bushings comprising: providing a condenser core, providing an outer composite insulator, and filling the gap between the condenser core and the outer composite insulator with a polyurethane foam prepared according to the process of claim 9.

11. An insulating material for pipes comprising a polyurethane foam prepared according to the process of claim 9.

12. A hollow core composite insulator comprising a polyurethane foam prepared according to the process of claim 9 in the space in the hollow core tube.

13. An encapsulation material for electrical components wherein the encapsulation material comprises, (a) a polyether polyol, (b) a polyolefin polyol, and (c) a polyester polyol obtainable obtained by epoxidation of an unsaturated fatty acid ester and subsequent ring-opening reaction with a compound containing active hydrogen, and (d) a polyisocyanate.

Description

EXAMPLES

List of Used Raw Materials

[0083] BAYGAL? K 55 (supplied by Bayer): [0084] colourless to yellow-coloured trifunctional polypropylene oxide/polyethylene oxide block copolymer; viscosity: ?600 mPas; hydroxyl value: 370-400 mg KOH/g. [0085] TEGOSTAB? B 8863 Z (supplied by Evonik): [0086] polyethermodified polysiloxane, recommended as foam stabilizer for PUR foams; [0087] LUPRANOL? 2095 (supplied by BASF): [0088] trifunctional polyetherpolyol with primary hydroxyl end groups; recommended for the production of elastic foam materials; viscosity: ?850 mPas; hydroxyl value: 35 mg KOH/g (DIN 53 240); [0089] ARALDITE? DY 3601 (supplied by Huntsman): [0090] Polypropyleneglcoldigylcidylether, epoxide number:2.47-2.60 eq/kg (ISO 3001); NYFLEX 820 (supplied by Nynas GmbH): [0091] liquid naphthenic hydrocarbons from petroleum, viscosity: 90-110 cSt at 40? C. (ASTM 445); [0092] Poly bd? R45 HTLO (supplied by CRAY VALLEY): [0093] liquid hydroxyl-terminated polybutadiene, viscosity: 5 Pas at 30? C., hydroxyl functionality: 2.5, molecular weight M.sub.n: 2800 g/mol, 1,2 vinyl-content: 20%; SOVERMOL? 1111 (supplied by BASF): [0094] branched polyetherester, viscosity: 300-700 mPas at 25? C. (DIN 53015); [0095] UOP L paste (supplied by UOP) [0096] 50% paste of a potassium calcium sodium aluminosilicate of the zeolite A type with an approximate pore size of 3 ? in castor oil; [0097] AEROSIL? 200 (supplied by Evonik) [0098] hydrophilic fumed silica with a specific surface area of 200 m.sup.2/g; [0099] SUPRASEC? 2447 (supplied by Huntsman): [0100] isocyanate blend containing about 60% 4,4-methylenediphenyl-diisocyanate, about 20%, 2,4-methylenediphenyl-diisocyanate and about 20% polymeric methylenediphenyldiisocyanate;

Preparation of Component A

[0101] Preparation of component A for Examples 1-3 (Ex. 1-Ex. 3) according to the invention and Reference Examples 1-3 (C1-C3):

[0102] All components of each formulation according to Table 1 with exception of SUPRASEC? 2447 are put to into a metal can of sufficient size in the given proportion to result in 200 g of polyol mixture. The mixture is then prepared by stirring the components at 23? C. with a propeller stirrer for about 2 minutes, resulting in component A.

Preparation of Component B:

[0103] As component B for Examples 1-3 (Ex. 1-Ex. 3) according to the invention and Reference Examples 1-3 (C1-C3) 100% SUPRASEC? 2447 of Huntsman is used.

Preparation of the Reactive Mixtures of Component A and B:

[0104] About 150 g of the component A and the corresponding amount of component B according to Table 1 are put to a metal can and then mixed at ambient temperature with a propeller stirrer for 2 min. 80 g of this reactive mixture is then subsequently used to produce foam and the reset to produce the plates for the tan delta testing as described in the following. The results are summarized in Table 1.

Production of Foam and Foam Stability Judgement:

[0105] 80 g of polyol/isocyanate mixture are put into a 200 ml cup and then stirred with a small high shear disperser mixer for 30 seconds at 2000 rpm. This shearing with this equipment is sufficient to introduce such amount of air to achieve about 30% volume increase due to foam formation. The generated foam is then cured at 23? C. for 72 hours. The aspect of the cured foam sample is then checked on homogeneity. The requirement to pass this foam stability test is to show no signs of collapse.

Judgement on Storage Stability of the Polyol Mixture:

[0106] It is required that the polyol mixture (component A) remains clear with no signs of separation over a period of 1 month at room temperature. A formulation showing incompatibility of components normally displays more than 1 phase after some time.

Viscosity Measurement:

[0107] The mixture of component A and B is subjected to Rheomat viscosity meter and the development of viscosity is registered until 15 Pas are reached. The time needed to achieve 15 Pas is recorded. The viscosity is measured according to DIN 53019

Tan ? and T.SUB.g .Measurement:

[0108] The mixture of component A and B is cast (without foaming) into molds and 1 and 2 mm thick plates are produced by curing the mixture for 4 hours at 90? C. The tan ? is then measured on the 2 mm thick plates according to IEC 60250.

[0109] The T.sub.g is measured by DMA on the 1 mm thick plate according to IEC 6721-2

[0110] The compositions according to Examples 1-3 provide a combination of long pot life, low T.sub.g (good low temperature flexibility), low tan delta (good electrical performance) and high storage stability, whereas the compositions according to Reference Examples 1-3

[0111] (C1-C3) do not achieve the targeted low Tg of <?50? C. and the required low tan delta of

[0112] <5% (RT) and <15% (100? C.).

TABLE-US-00001 TABLE 1 Composition Ex. 1 Ex. 2 Ex. 3 C1 C2 C3 Component A/ pbw *.sup.) BAYGAL? K 55 9.50 12.00 10.00 23.00 17.27 21.00 Poly bd? R45 45.70 40.10 58.00 HTLO SOVERMOL? 28.60 25.40 16.00 15.50 1111 TEGOSTAB? 3.00 3.00 3.00 3.00 B 8863 Z LUPRANOL? 70.00 55.85 62.20 2095 ARALDITE? 2.00 2.50 2.00 2.00 1.88 2.00 DY 3601 NYFLEX 820 9.50 15.00 9.00 4.20 9.50 UOP L paste 5.00 5.00 AEROSIL? 200 1.70 2.00 2.30 2.30 Component B/ pbw *.sup.) SUPRASEC? 25.00 25.00 22.00 27.00 27.00 24.50 2447 Pot Life at 25? C./ 135 200 103 378 n.d. n.d. min Storage Stability + + n.d. **.sup.) + ? ? of A T.sub.g/? C. (4 h/90? C.) ?67 n.d. ?65 ?37 n.d. n.d. tan ? at 23? C. 4.0% n.d. 4.5% 8.0% n.d. n.d. (50 Hz) tan ? at 100? C. 12.3% n.d. 7.0% 387% n.d. n.d. (50 Hz) *.sup.) pbw: parts by weight **.sup.) n.d.: not determined