Composition of allophanate and hydrophobic resin

Abstract

The invention relates to a composition for preparing (poly)urethane from an allophanate and from a hydrophobic resin. The invention also relates to the use of this composition as a replacement for poly(methylene diphenyl diisocyanate) (pMDI), in particular for the preparation of a material for encapsulating an electrical device.

Claims

1. A composition for preparing a (poly)urethane, the average functionality of which is greater than 2, comprising (a) an isocyanate component with an NCO functionality comprised between 1.9 and 2.7 and comprising at least one allophanate with an NCO functionality equal to 2+/5% and of formula (I) ##STR00006## wherein R.sup.1 represents the residue of a mono-alcohol compound comprising an ether or polyether function after reaction of the hydrogen of the OH function with a compound with an isocyanate function; R.sup.2and R.sup.3, either identical or different, represent a hydrocarbon group, comprising a derived or non-derived isocyanate function; (b) at least one hydrophobic resin with hydroxyl functions with a molar weight of more than 500 g/mol; with an OH functionality equal to 2 or greater than 2; of solubility parameters with a value of less than 20.4 MPa.sup.1/2 and different from a polyamine selected from the group consisting of acrylonitrile/butadiene copolymers with amine end functions, selected from the group consisting of a linear or branched poly-propylene with hydroxyl groups; a linear or branched poly-propylene with hydroxyl end groups; a linear or branched hydroxylated poly-butadiene with hydroxyl groups; a linear or branched hydroxylated poly-butadiene with hydroxyl end groups; and a linear or branched hydroxylated poly-butadiene.

2. The composition according to claim 1, wherein the molar ratio defined by (number of NCO functions/number of OH functions) ranges from 0.9 to 3; from 1 to 3; from 0.9 to 1.5; from 1 to 1.5; from 0.9 to 1.2 or from 1 to 1.2.

3. The composition according to claim 1, comprising an isocyanate component (a) with NCO functionality selected from the group consisting of an NCO functionality ranging from 1.9 to 2.5; an NCO functionality ranging from 1.9 to 2.3; an NCO functionality ranging from 1.9 to 2.2; an NCO functionality ranging from 1.9 to 2.1; an NCO functionality ranging from 2 to 2.5; an NCO functionality ranging from 2 to 2.3; and an NCO functionality ranging from 2 to 2.2.

4. The composition according to claim 1, comprising at least one allophanate with NCO functionality ranging from 1.95 to 2.05.

5. The composition according to claim 1, wherein R.sup.1 represents the residue of a mono-alcohol compound selected from the group consisting of components of formula (II)
T-[OCH(L)-CH.sub.2].sub.nOH(II) wherein T represents a linear C.sub.1-C.sub.20 group or a branched C.sub.1-C.sub.20-alkyl group, a group of formula Q-CO wherein Q represents a linear C.sub.1-C.sub.20-alkyl group or a branched C.sub.1-C.sub.20-alkyl group; n represents an integer ranging from 1 to 10; and L represents H, an alkyl group, or a polyether group; and R.sup.2 and R.sup.3, either identical or different, represent a hydrocarbon group comprising a derived or non-derived isocyanate function wherein the hydrocarbon group is selected from the group consisting of an aliphatic, cycloaliphatic, heterocyclic and aromatic hydrocarbon group.

6. The composition according to claim 1, wherein the derived isocyanate function is different from an isocyanurate function and is selected from the group consisting of carbamate, urea, biuret, urethane, uretinedione, acyl urea, masked isocyanate, and allophanate functions.

7. The composition according to claim 1, wherein the allophanate is a homo-allophanate, R.sup.2 and R.sup.3 being identical, or wherein the allophanate is a mixed allophanate, R.sup.2 and R.sup.3 being different.

8. The composition according to claim 1, comprising a mixture of allophantes comprising at least 25% by mass of at least one mono-allophanate.

9. The composition according to claim 1, wherein the at least one allophanate comprises a mixture of allophanates comprising at least one allophanate selected from the group consisting of bis-allophanate and tris-allophanate.

10. The composition according to claim 1, comprising a hydrophobic resin with an OH functionality selected from the group consisting of a an OH functionality ranging from 2 to 25; an OH functionality ranging from 2 to 15; an OH functionality ranging from 2 to 10; an OH functionality ranging from 2 to 5; an OH functionality ranging from 2.1 to 25; an OH functionality ranging from 2.1 to 15; an OH functionality ranging from 2.1 to 10; and an OH functionality ranging from 2.1 to 5.

11. The composition according to claim 1, comprising a hydrophobic resin wherein the molecular weight is greater than 1,000 g/mol.

12. The composition according to claim 1, comprising a hydrophobic resin wherein the solubility parameters have a value of less than 18.4 MPa.sup.1/2 or less than 16.4 MPa.sup.1/2 or comprised between 16.4 and 18.4 MPa.sup.1/2.

13. The composition according to claim 1, also comprising at least one polyfunctional isocyanate tricondensate (c) or at least one additive of the polyol type and different from the resin (b) or simultaneously at least one polyfunctional isocyanate tricondensate (c) and at least one additive of the polyol type and different from the resin (b).

14. The composition according to claim 1, further comprising at least one polyfunctional isocyanate tricondensate (c) selected from the group consisting of a compounds of formula (III): ##STR00007## wherein R.sup.4, R.sup.5 and R.sup.6 represent independently an aliphatic, cycloaliphatic, heterocyclic or aromatic heterocarbon or hydrocarbon group, comprising a derived or non-derived isocyanate function; m represents 0, 1 or 2; third bullet point, A represents a group selected from the group consisting of an isocyanurate group, an imino oxadiazine dione group, an oxadiazine trione group, and a biuret group of formulae (A1) to (A4) respectively, ##STR00008## wherein B represents independently a radical selected from the group consisting of hydrogen; a C.sub.1-C.sub.20 hydrocarbon group; a heterocarbon group comprising at least one heteroatom selected from the group consisting of O, N, S, and Si; a C.sub.1-C.sub.20 heterocarbon group comprising at least one heteroatom selected from the group consisting of O, N, S, and Si; and a group of formula (B1) ##STR00009## wherein n represents 3 or 4 and Q represents a group selected from the group consisting of a hydrocarbon group, an alkoyl group, a hydrocarbon group, an aliphatic, cycloaliphatic, and a heterocyclic or aromatic heterocarbon group, comprising a derived or non-derived isocyanate function.

15. The composition according to claim 1, further comprising at least one polyfunctional isocyanate tricondensate (c) which is a non-derivatized polyisocyanate isocyanurate.

16. The composition according to claim 1 further comprising at least one polyfunctional isocyanate tricondensate (c) having one or more of the following characteristics: (i) the weight ratio between the allophanate of the isocyanate component (a) and the polyfunctional isocyanate tricondensate (c) having a range selected from the group consisting of from 60/40 to 90/10, from 30/70 to 90/10, from 60/40 to 80/20, from 30/70 to 80/20, from 60/40 to 85/15, and from 30/70 to 85/15; (ii) the polyfunctional isocyanate tricondensate (c) stems from a tricondensation reaction wherein the transformation rate of the isocyanate monomer(s), either identical or different, into polyfunctional polyisocyanate tricondensate is selected from the group consisting of greater than 8%, greater than 10%, and greater than 15%; and (iii) the polyfunctional isocyanate tricondensate (c) comprises between 1 and 99% by weight of biuret or between 2 and 75% by weight of biuret.

17. A method comprising hardening the composition of claim 1.

18. A method comprising encapsulating an electric device with a (poly)urethane prepared by reacting the composition of claim 1.

19. An electric device encapsulated according to the method of claim 18.

Description

EXAMPLE 1

(1) Equipment

(2) The polyisocyanate P1 was prepared according to the method described in WO-2010/067005 from Rhodasurf LA30 (Rhodia) and from hexamethylene diisocyanate. The main characteristics of this product are: NCO functionality: 12.6%, dynamic viscosity (at 25 C.): 130 mPa.Math.s, density: 1.13.

(3) The polyisocyanate P2 according to the invention is a mixture (60/40 v/v) of polyisocyanate P1 with Tolonate HDT (Perstorp) which is a polyisocyanate prepared from hexamethylene diisocyanate. The main characteristics of this product are: NCO functionality: 16.5%, dynamic viscosity (at 25 C.): 363 mPa.Math.s, density: 1.13.

(4) PolyBD 45R HTO (Cray Valley) is a poly-butadiene with end hydroxyls (HTPB) of formula:

(5) ##STR00005##

(6) The main characteristics of this product are: OH functionality: 1.39%, dynamic viscosity (at 25 C.): 6 665 mPa.Math.s, density: 0.9.

(7) Tolonate HDT-LV2 (Perstorp) is a polyisocyanate prepared from hexamethylene diisocyanate. The main characteristics of this product are: NCO functionality: 23%, dynamic viscosity (at 25 C.): 600 mPa.Math.s, density: 1.13.

(8) Desmodur VL (Bayer) is a polyisocyanate prepared from a polymer of methylene diphenyl diisocyanate. The main characteristics of this product are: NCO functionality: 31.5%, dynamic viscosity (at 25 C.): 91 mPa.Math.s, density: 1.24.

(9) Results

(10) The viscosity of a mixture of at least two liquids may be calculated by the Refutas equation, by considering that the miscibility of two components is complete. Depending on whether the obtained experimental results are consistent with the calculated data, the miscibility of the components of the mixture will be determined.

(11) The first step consists in calculating the viscosity index (viscosity blending indexVBI) for each component of the mixture:
VBN=14.534In[In(v+0.8)]+10.975
wherein v represents the viscosity in centistokes.

(12) The following step consists in calculating the viscosity index of the mixture (viscosity blending indexVBI-blend):
VBN.sub.Blend=[x.sub.AVBN.sub.A]+[x.sub.BVBN.sub.B]+ . . . +[x.sub.NVBN.sub.N]

(13) Finally, the viscosity of the mixture is obtained by means of the equation:

(14) $v=\exp \left(\exp \left(\frac{{\mathrm{VBN}}_{\mathrm{Blend}}-10.975}{14.534}\right)\right)-0.8,$

(15) HTPB and polyisocyanates are mixed in different ratios by means of a spatula, in particular in ratios for which HTPB is a majority and represents at least 50% of the mixture, or even between 70 and 90% of the mixture.

(16) The dynamic viscosity (at 25 C.) is measured and then converted into a kinematic viscosity value from the respective densities of the products and of the mixtures.

(17) Finally, comparisons are made.

COMPARATIVE EXAMPLE 1.1

HTPB and Tolonate HDT-LV2 Mixture

(18) TABLE-US-00001 Amount of HTPB Calculated viscosity of the Measured viscosity of (% by mass) mixture (mm.sup.2 .Math. s.sup.1) the mixture (mm.sup.2 .Math. s.sup.1) 100 7405 7405 90 5448 6595 80 4050 6286 70 3042 6035 60 2307 5540 50 1767 2151 30 1064 1338

EXAMPLE 1.2

HTPB and Polyisocyanate P1 Mixture

(19) TABLE-US-00002 Amount of HTPB Calculated viscosity of the Measured viscosity of (% by mass) mixture (mm.sup.2 .Math. s.sup.1) the mixture (mm.sup.2 .Math. s.sup.1) 100 7405 7405 90 4300 5247 80 2582 4159 70 1600 3013 60 1020 2434 50 668 1684 30 309 752

EXAMPLE 1.3

HTPB and Polyisocyanate P2 Mixture

(20) TABLE-US-00003 Amount of HTPB Calculated viscosity of the Measured viscosity of (% by mass) mixture (mm.sup.2 .Math. s.sup.1) the mixture (mm.sup.2 .Math. s.sup.1) 100 7405 7405 90 5070 5862 80 3529 4864 70 2495 4261 60 1790 3208 50 1302 2337 30 717 1104

EXAMPLE 1.4

HTPB and Desmodur VL Mixture

(21) TABLE-US-00004 Amount of HTPB Calculated viscosity of the Measured viscosity of (% by mass) mixture (mm.sup.2 .Math. s.sup.1) the mixture (mm.sup.2 .Math. s.sup.1) 100 7405 7405 90 3953 5874 80 2207 4875 70 1283 3990 60 775 3285 50 485 1578 30 209 543

(22) The viscosities measured for the HTPB mixtures with polyisocyanates P1 and P2 are the closer to the calculated viscosities. Better compatibility between HTPB and these polyisocyanates P1 and P2 is therefore seen like with the other polyisocyanates.

(23) In particular, for a constant ratio of the NCO functionalities/OH functionalities (NCO/OH=1.03), the mixtures based on polyisocyanates P1 and P2 have lower viscosities than the mixtures based on Desmodur VL and Tolonate HDT-LV2 whereas the viscosity of Desmodur VL is lower than that of the polyisocyanates P1 and P2.

(24) TABLE-US-00005 Tolonate Desmodur Polyisocyanates HDT-LV2 VL P1-P2 HTPB (%) 14 11 23-19 Polyisocyanate (%) 86 89 77-81 Viscosity (mm.sup.2 .Math. s.sup.1) 6140 5870 4129-4810