Polyisocyanate polyaddition polyol manufacturing process using stabilizers

Abstract

PIPA polyols are made by reacting a low equivalent weight polyol with a polyisocyanate in the presence of a stabilizer. Low amounts, if any, of water are present. Useful stabilizers include functionalized linear or branched polyethers having at least one polyether segment having a molecular weight of 200 to 8000, wherein the functionalized polyether is terminated at one end with one or more isocyanate groups or with one or more isocyanate-reactive groups linked to the polyether through one or more urea and/or urethane groups, and further wherein all or a portion of such functionalized polyether contains one or more biuret, isocyanurate, urea or allophonate groups.

Claims

1. A process for preparing a dispersion of polyisocyanate polyaddition particles in a base polyol, comprising forming an agitated mixture of a low equivalent weight polyol having a hydroxyl equivalent weight of up to 80, one or more polyisocyanate compounds, a stabilizer, a base polyether polyol having a hydroxyl equivalent weight of at least 200, and reacting the low equivalent weight polyol with the polyisocyanate compound(s) in the presence of the base polyether polyol and the stabilizer, to form the dispersion of polyisocyanate polyaddition particles in the base polyol, wherein the stabilizer includes one or more functionalized linear or branched polyether compounds having at least one polyether segment that have a molecular weight of 200 to 8000, wherein the functionalized linear or branched polyether compounds are terminated at one end with one or more isocyanate groups or with one or more isocyanate-reactive groups linked to the polyether through one or more urea and/or urethane groups, and further wherein all or a portion of such functionalized linear or branched polyether compounds contain one or more biuret, isocyanurate, urea or allophonate groups.

2. The process of claim 1 wherein the functionalized linear or branched polyether compound(s) are a reaction product of a monofunctional polyether having a molecular weight of 700 to 8000 and a polyisocyanate having an isocyanate equivalent weight of up to 300.

3. The process of claim 2, wherein all or a portion of the functionalized linear or branched polyether compound(s) contain one or more isocyanurate groups.

4. The process of claim 1, wherein the functionalized linear or branched polyether compound(s) containing one or more isocyanurate groups have a structure represented by ##STR00015## where each R represents the residue, after removal of isocyanate groups, from a starting polyisocyanate compound having the structure R(NCO).sub.x; each x is a number from 2 to 6 representing the number of isocyanate groups on the starting polyisocyanate compound, PE represents a polyether chain of 700 to 8000 molecular weight, each X independently is O or NH, and each A is independently ##STR00016##

5. The process of claim 1 wherein the stabilizer contains 3 to 15% by weight isocyanate groups.

6. The process of claim 1 wherein 92 to 100% of the hydroxyl groups of the base polyol are secondary hydroxyl groups.

7. The process of claim 1 wherein the aminoalcohol is triethanolamine or a mixture of 75-99.9 weight-% triethanolamine and 0.1 to 25 weight-% of another low equivalent weight polyol.

Description

EXAMPLES 1-3

(1) Stabilizer A is made by combining 50 parts by weight of Monol X and 50 parts 80/20 TDI, and stirring the mixture at room temperature in a closed vessel. The theoretical isocyanate content (not considering biuret, urea, allophonate or isocyanurate formation) based on amounts of monol and 80/20 TDI is 23.6%. The measured isocyanate content of the product is 16%, which indicates that isocyanurate (and possibly biuret, urea and/or allophonate) formation has occurred due to the presence of potassium acetate.

(2) Stabilizer B is made by combining 75 parts by weight of Monol X and 25 parts 80/20 TDI, and stirring the mixture in a closed vessel at room temperature. The theoretical isocyanate content (not considering biuret, urea, allophonate or isocyanurate formation) based on amounts of monol and 80/20 TDI is 11.2%. The measured isocyanate content of the product is 5.9%, which indicates that isocyanurate (and possibly biuret, urea and/or allophonate) formation has occurred due to the presence of potassium acetate.

(3) Stabilizer C is made by combining 90 parts by weight of Monol X and 10 parts 80/20 TDI, and stirring the mixture in a closed vessel at room temperature. The theoretical isocyanate content (not considering biuret, urea, allophonate or isocyanurate formation) based on amounts of monol and 80/20 TDI is 3.7%. The measured isocyanate content of the product is 1.5%, which indicates that isocyanurate (and possibly biuret, urea and/or allophonate) formation has occurred due to the presence of potassium acetate.

EXAMPLE 1

(4) 5.4 parts of 80/20 TDI are mixed with 4.2 parts of Stabilizer C at room temperature. The resulting mixture is blended into 88 parts of Polyol I on a high speed laboratory mixer. A PIPA dispersion is then made by adding 4.5 parts of triethanolamine and 0.2 parts of zinc carboxylate catalyst and mixing for 5 minutes. After cooling to room temperature, a stable PIPA polyol is obtained. Particle size is measured using a Beckman Coulter LS Particle Size Analyzer. The viscosity of the dispersion is measured using a Bohlin rheometer with cone-and-plate geometry, operated in a rotational mode at 20 C. The viscosity is recorded at its equilibrium value. Results of the particle size and viscosity measurements are as reported in Table 1.

EXAMPLE 2

(5) 4.1 parts of 80/20 TDI are mixed with 4.2 parts of Stabilizer A. The resulting mixture is blended into 88 parts of Polyol I on a high speed laboratory mixer. A PIPA dispersion is then made in the general manner described for Example 1. Particle size and viscosity are measured as before and are as reported in Table 1.

EXAMPLE 3

(6) 5.2 parts of 80/20 TDI are mixed with 2.6 parts of Stabilizer B. The resulting mixture is blended into a mixture of 88 parts of Polyol I and 2 parts of Seed PIPA polyol A on a high speed laboratory mixer. A PIPA dispersion is then made in the manner described with respect to Example 1. Particle size and viscosity are measured and reported in Table 1.

(7) The measured viscosity and particle size distribution for each of these experiments are as reported in Table 1.

(8) TABLE-US-00001 TABLE 1 Sample Viscosity, Designation Pa .Math. s Particle Size Comparative Unstable Unstable overnight. A* 1 1.025 Multimodal with a main fraction having a broad distribution of particles from 1 to 30 m (centered at about 5 m and another large fraction from 30 to 200 m. 2 1.221 Trimodal, with a fraction of particles from 0.05 to 1 m, a main fraction from 1 to 5 m, and a small shoulder centered at 10 m. 3 1.041 Bimodal, with a largest fraction at 0.05 to 0.7 m and a smaller but significant fraction at 0.7 to 4 m.

(9) The results of Examples 1-3 show that Stabilizers A, B and C are effective in stabilizing the PIPA dispersion and getting small particles, when used by themselves or, in the case of Example 3, in conjunction with Seed PIPA Polyol A. The PIPA particles do not settle. The improvements in particle size and stability do not come at the expense of any significant increase in viscosity.

EXAMPLES 4 AND 5

(10) Stabilizer D is made by combining 50 parts by weight of Monol X and 50 parts 80/20 TDI, and stirring the mixture at 50 C. in a closed vessel. The theoretical isocyanate content (not considering biuret, urea, allophonate or isocyanurate formation) based on amounts of monol and 80/20 TDI is 23.6%. The measured isocyanate content of the product is 13.7%, which as before indicates isocyanurate and possibly biuret, urea and/or allophonate formation.

(11) Stabilizer E is made by combining 80 parts by weight of Monol X and 20 parts 80/20 TDI, and stirring the mixture in a closed vessel at 50 C. The theoretical isocyanate content (not considering biuret or isocyanurate formation) based on amounts of monol and 80/20 TDI is 7.6%. The measured isocyanate content of the product is 3.5%, which as before indicates isocyanurate and possibly biuret, urea and/or allophonate formation.

(12) Examples 4 and 5 are made using Stabilizers D and E, respectively. To make Example 4, 4.3 parts of Stabilizer D is diluted with 4.3 parts 80/20 TDI. 88 parts of Polyol I are mixed with 4.5 parts of triethanolamine and 0.2 parts of the zinc carboxylate catalyst. The stabilizer/TDI mixture is then added to the polyol/triethanolamine/catalyst mixture and mixed for 5 minutes. After cooling to room temperature, a stable PIPA polyol is obtained.

(13) To make Example 5, 2.4 parts of Stabilizer E are diluted with 5.4 parts of 80/20 TDI. This mixture is used to make a PIPA polyol as described with respect to Example 1.

(14) In both cases, particle size and viscosity are measured as before. Results are as indicated in Table 2.

(15) TABLE-US-00002 TABLE 2 Sample Viscosity, Designation Pa .Math. s Particle Size 4 1.30 Bimodal, with a large fraction of particles having sizes from 0.05 to 0.7 m, and another large fraction of particles having sizes from 0.7 to 4 m. There is a very small fraction of particles of about 10 m. 5 2.40 Bimodal, with a large fraction of particles having sizes from 0.05 to 0.8 m (centered at about 0.15 m, and another large fraction of particles having sizes from 0.8 to 6 m. There is a small fraction of particles of about 10 m.

(16) Both dispersions contain very small particles and are stable against particle settling. Viscosities are acceptable in each case. Both are considered very high quality dispersions and give good quality foams as reported later.

EXAMPLES 6-10

(17) Stabilizers F, G, H and I are made by mixing Monol X with 80/20 TDI and allowing the mixture to react at 20 C. in a closed vessel. The ratios of starting materials, theoretical (not considering biuret, urea, allophonate and isocyanurate formation) and measured isocyanate contents and appearance are as indicated in Table 3.

(18) TABLE-US-00003 TABLE 3 TDI/ Theoretical Measured Monol X NCO NCO Weight content, content, Stabilizer Ratio wt.-% wt.-% Appearance F 10/90 3.7 2.3 Yellow liquid G 15/85 6.4 3.6 Yellow liquid H 25/75 11.2 7.8 Yellow liquid I 75/25 36.0 32.5 Crystalline precipitate in yellow liquid phase

(19) Stabilizers F, G H and I are separately blended with 80/20 TDI and the resulting blends are used to make PIPA polyols Examples 6-10. The type and content of stabilizer in each PIPA polyol product is as indicated in Table 4.

(20) TABLE-US-00004 TABLE 4 Stabilizer (Wt.-% in PIPA Example polyol product) 6 F (2.1) 7 H (2.6) 8 G (4.6) 9 H (6.1) 10 I (8.2)

(21) In each case, 88 parts of Polyol I are blended on a high speed laboratory mixer with the isocyanate/stabilizer mixture, followed by addition of 4.5 parts of triethanolamine and 0.2 parts of the zinc carboxylate catalyst to produce a PIPA polyol dispersion. Mixing is continued without additional applied heat for another 9 minutes after the final addition is completed in all cases except Example 7, in which the mixing is continued for 15 minutes. Particle size and viscosity are measured as before. Results are as indicated in Table 5.

(22) TABLE-US-00005 TABLE 5 Sample Viscosity, Designation Pa .Math. s Particle Size 6 1.04 Monomodal, with particles mainly from 2 to 40 m, and a small shoulder of particles up to 100 m. The stability of this dispersion is marginal (but much better than Comparative Sample A). 7 2.05 Trimodal with a largest fraction between 1 and 6 m and smaller fractions between 0.1 and 0.6 m and 6-20 m. The dispersion has good stability. 8 1.26 Trimodal with a largest fraction between 1 and 3 m and smaller fractions between 0.1 and 1 m and 3-20 m. The dispersion has good stability. 9 2.07 Bimodal with a largest fraction between 0.05 and 1 m centered on 0.3 m. A smaller fraction has 1-10 m particles, centered on 3 m. Very good dispersion. 10 1.28 Polymodal with most particles 1-5 m, but a significant fraction of 5-100 m particles.

(23) These examples show the effect of varying the stabilizer composition, as well as the stabilizer content in the final PIPA polyol.

EXAMPLES 11-14

(24) Stabilizer D is blended with 80/20 TDI at room temperature and used in different quantities to make PIPA polyol in Examples 11-14, as shown in Table 6:

(25) TABLE-US-00006 TABLE 6 Example Stabilizer parts in No(s). PIPA polyol 11 0.6 12 1.9 13 11.2 14 11.2

(26) Examples 11 and 12 are made using the same general method described with respect to Example 4. Examples 13 and 14 made using the same general method as described with respect to Example 1.

(27) The formulation, viscosity and particle size are indicated in Table 7.

(28) TABLE-US-00007 TABLE 7 Ex. 11 Ex. 12 Ex. 13 Ex. 14 Polyol A 89.5 88.9 84.2 82.2 Seed PIPA polyol B 0 0 0 2 Zinc carboxylate 0.2 0.2 0.2 0.2 catalyst TDI/Stabilizer 5.6 6.3 11.2 11.2 mixture Properties Viscosity, Pa .Math. s 1.12 1.26 1.58 1.68 Particle size, m 2-30 0.05-6 0.05-1 0.05-1

(29) Example 11 shows that even a very small amount of the stabilizer of the invention containing high level of isocyanurate produces a product having better particle size and stability than Comparative Sample A. Increasing the amount of stabilizer gives better results, as shown in Examples 12 and 13. Adding a Seed PIPA Polyol B (Example 14) provides no additional benefit compared with Example 13.

EXAMPLES 15-18

(30) Stabilizer J is made by mixing Monol X with 80/20 TDI at a 75/25 weight ratio at room temperature to produce a prepolymer having an isocyanate content of 6.3%. The theoretical NCO group content (not considering biuret, urea, allophonate and isocyanurate formation) is 11.2%, which indicates that isocyanurate (and possibly biuret, urea and/or allophonate) groups have been formed.

(31) Example 15, 16 and 17 are made by mixing 2.6 parts of Stabilizer J with 5.2 parts of 80/20 TDI at room temperature. This isocyanate mixture is added at room temperature to 88 parts of Polyol I (Example 15), Polyol II (Example 16) and Polyol III (Example 17) on a high speed laboratory mixer and mixed for 60 seconds. Then a mixture of 4.5 parts of triethanolamine and 0.2 parts of a zinc carboxylate catalyst are added over sixty seconds with continued mixing. The reaction mixture is seen to whiten a few seconds after the triethanolamine addition is started. Mixing is continued another nine minutes without further application of heat after the triethanolamine/catalyst addition is complete. Particle size and viscosity are measured and data presented in Table 8.

(32) Example 18 is made by blending 8.2 parts of Stabilizer J with 10 parts of TDI. This blend is added to a mixture of 71 parts of Polyol I and 4 parts of Example 3. 9 parts of triethanolamine and 0.2 parts of a zinc carboxylate catalyst are then added, and a dispersion is made as described with respect to Example 1. The final product (Example 18) is of good quality as reported in Table 8.

(33) TABLE-US-00008 TABLE 8 Stabilizer J, weight Base percent in Ex. 3, Viscosity, Particle Designation Polyol product parts Pa .Math. s Size, m 15 I 2.6 0 1.02 0.1-5 16 II 2.6 0 1.24 0.1-5 17 III 2.6 0 1.52 0.1-5 18 I 8.2 4 1.74 1-10

(34) As can be seen from the data in Table 8, Stabilizer J effectively stabilizes PIPA particles in all three types of conventional polyols evaluated. At higher solids, good particle size distribution, viscosity and dispersion stability is obtained.

EXAMPLES 19 and 20

(35) Stabilizer K is made by mixing Monol Y with 80/20 TDI at a 80/20 weight ratio at room temperature to produce a prepolymer having an isocyanate content of 7.3%. This is only slightly lower than the 7.6% theoretical isocyanate content (not considering biuret, urea, allophonate and isocyanurate formation), which indicates that few if any such groups have formed.

(36) Stabilizer L is made in the same manner as Stabilizer K, except a quaternary ammonium trimerization catalyst is added. The prepolymer has an isocyanate content of 3.9% versus the theoretical amount of 7.6%, which indicates the formation of isocyanurate and possible biuret, urea and/or allophonate groups.

(37) Examples 19 and 20 are made by mixing 2.4 parts of the stabilizer (Stabilizer K in the case of Example 19 and Stabilizer L in the case of Example 20) with 5.2 parts of 80/20 TDI at room temperature. This isocyanate mixture is added to a blend of 86 parts Polyol I and 2 parts of Example 3. 4.5 parts of triethanolamine mixed with 0.2 parts of the zinc carboxylate catalyst are added and the dispersion is mixed for additional 9 minutes.

(38) Example 19 has particles in the size range of 3 to 25 m and is more stable than any of Comparative Samples A-C. Example 20 has a low viscosity (0.98 Pa.Math.s) and small particle size (0.05-2 m), illustrating the advantage of incorporating isocyanurate linkages into the stabilizer.

EXAMPLES 21-23

(39) Stabilizer M is made by reacting 80 parts of Monol Y with 20 parts 80/20 TDI in presence of 0.05 parts of a quaternary ammonium trimerization catalyst. Stabilizer M has an isocyanate content of 2.4% versus theoretical value of 7.6%, indicating isocyanurate and possibly biuret, urea and/or allophonate formation. The very low value relative to the theoretical value indicates that Stabilizer M contains a high proportion of isocyanurate rings relative to most of the other stabilizers.

(40) PIPA polyols of Examples 21-23 are made using various amounts of Stabilizer M as indicated in Table 9. The stabilizer is mixed with 5.4 parts of 80/20 TDI and blended into a mixture of 86 parts Polyol I and 2 parts of Example 3. A mixture of 4.5 parts triethanolamine and 0.2 parts of the zinc carboxylate catalyst are added and a dispersion is made as before. The viscosity and particle size are as indicated in Table 9.

(41) TABLE-US-00009 TABLE 9 Base Stabilizer M, wt.-% Solids, Viscosity, Particle Example Polyol in product % Pa .Math. s Size, m 21 I 2.3 10% 11.3 0.05-5 22 I 1.0 10% 2.40 0.5-5 23 I 0.3 10% 1.10 0.5-5

(42) The data in Table 9 shows the effect of the level of a stabilizer having a low NCO content on final viscosity of PIPA product. Example 21 is thixotropic, as its viscosity drops from the value reported in Table 9 to a much lower value with increasing shear. The thixotropic behavior of Example 21 is believed to be due to either or both of the higher amounts of stabilizer M used to make the dispersion and the high proportion of isocyanurate groups in Stabilizer M. These factors may create a significant crosslinking effect with the base polyol during the formation of the dispersion. On another hand particle size and stability are good for all three examples over a period of several months.

EXAMPLES 24 and 25

(43) Stabilizer N is prepared as follows. 80 parts of Monol Y and 20 parts of 80/20 TDI are reacted at room temperature in the presence of 0.05 parts of an N-hydroxyalkylquaternary ammonium carboxylate isocyanate trimerization catalyst. An exotherm is noticed and the reaction is allowed to proceed for a couple of hours, reaching an isocyanate content of about 3.5% versus theoretical 7.6% (as before, indicative of isocyanurate and possibly biuret, urea and/or allophonate formation). This mixture is then reacted with an excess of TEOA in order to cap all the residual isocyanate groups with the triethanolamine. The resulting capped material is designated Stabilizer N.

(44) Example 24 is prepared by mixing 88 parts of Polyol IV with 4.34 parts of 80/20 TDI on a high speed laboratory mixer. A mixture of 3.54 parts triethanolamine, 0.2 parts of the zinc carboxylate catalyst and 1.93 parts of Stabilizer N is then added over sixty seconds with continued stirring. After the addition is completed, the mixture is stirred another 9 minutes. All components are at room temperature when added. The resulting PIPA polyol has a viscosity of 0.81 Pa.Math.s. It has a bimodal particle size distribution with a larger fraction of particles having sizes from 0.1 to 0.9 m and a slightly smaller fraction having particle sizes of 0.9 to 3 m. This is considered to be a very good dispersion.

(45) Example 25 is prepared by mixing 88 parts of Example 24 (prepared the same day) with 4.34 parts of 80/20 TDI on a high speed laboratory mixer. A mixture of 3.54 parts triethanolamine, 0.2 parts of the zinc carboxylate catalyst and 1.93 parts of Stabilizer N is then added over sixty seconds with continued stirring. After the addition is completed, the mixture is stirred another 9 minutes. The resulting PIPA polyol has a viscosity of 1.30 Pa.Math.s at 20% solids by weight. It has a bimodal particle size distribution with a larger fraction of particles having sizes from 0.2 to 0.9 m and a slightly smaller fraction having particle sizes of 0.9 to 7 m. A small shoulder of larger particles is present. This is considered to be a very good dispersion, with low viscosity and small particles.

EXAMPLE 26

(46) Stabilizer O is made by reacting 80 parts of Monol X with 20 parts of 80/20 TDI at room temperature in a closed vessel. Stabilizer O has an isocyanate content of 1.8% versus theoretical value of 7.6%, indicating isocyanurate and possibly biuret, urea and/or allophonate formation.

(47) Example 26 is made using by blending 9.4 parts of triethanolamine and 0.2 parts of the zinc carboxylate catalyst into a mixture of 78 parts Polyol V and 2 parts of Seed PIPA Polyol B. 2.9 parts of stabilizer O mixed with 11.4 parts of 80/20 TDI are added, followed by additional 9 minutes of mixing. Particle size is 0.1-2 microns and viscosity is 3.0 Pa.Math.s. The 20% solids product is stable.

(48) Foaming Experiments

(49) Box foams are made by hand mixing at room temperature all components listed in Table 10 below. The resulting reaction mixture is poured into an open box and allowed to expand and cure in the box. PIPA polyols from Examples 4, 5, 7, 9, 15, 16 and 17 are used to make foams 4-F, 5-F, 7-F, 9-F, 15-F, 16-F and 17-F, respectively. Foam density, compression force deflection (40%), resilience, airflow and compression set are measured according to ASTM test methods. Results are as indicated in Table 10.

(50) TABLE-US-00010 TABLE 10 Designation Control A* Control B* 4-F 5-F 7-F 9-F 15-F 16-F 17-F Ingredient Polyol I 100 75 0 0 0 0 0 0 0 SAN CPP.sup.1 0 25 0 0 0 0 0 0 0 PIPA Polyol 0 0 100 100 100 100 100 100 100 Amine Catalysts 0.15 0.15 0.15 0.16 0.15 0.15 0.16 0.16 0.16 (Dabco 33 LV and Niax A1, 2:1 ratio) Stannous Octoate 0.15 0.15 0.1 0.1 0.15 0.15 0.1 0.1 0.1 Water 3.5 3.5 3.5 3.5 3.5 3.5 3.5 3.5 3.5 80/20 TDI (index) 115 115 110 110 115 115 115 115 115 Properties Density, kg/m.sup.3 29.3 29.5 28.7 28.3 28.2 27.1 26.6 27.2 26.9 CFD, 40%, kPa 3.9 5.1 4.8 4.8 5.2 5.6 4.5 4.6 5.1 Resilience, % 39 32 37 35 33 38 33 30 30 Airflow, L/m (scfm) 109 (3.8) 91 (3.2) 126 (4.4) 123 (4.3) 154 (5.4) 37 (1.3) 143 (5.0) 114 (4.0) 97 (3.4) 75% Comp. Set, % 5.7 9.2 6.4 5.6 5.1 10.6 5.3 4.9 6.4 *Not an example of the invention. .sup.1A copolymer polyol containing dispersed styrene-acrylonitrile particles.

(51) The data in Table 10 shows that PIPA polyols of the invention can be used to make polyurethane foam having properties equivalent or better than foam made using a conventional, unfilled polyol (Control A) or a conventional polymer polyol which has dispersed styrene-acrylonitrile particles (Control B).

(52) Comparative Sample C

(53) Comparative Stabilizer P is made by reacting with 70 parts of Monol Z with 30 parts of 80/20 TDI at room temperature in a closed vessel. The NCO content is 25% versus theoretical 31.1%. The difference is believed to be due to biuret, urea and/or allophonate formation caused by the presence of water in hydrophilic Monol Z.

(54) Example C is made by mixing 3.9 parts of 80/20 TDI with 2.9 parts of Comparative Stabilizer P at room temperature and adding the mixture to 89 parts of Polyol I. Subsequently, 4.4 parts of triethanolamine mixed with 0.2 parts of zinc carboxylate catalyst are added and the resulting mixture stirred for an additional 9 minutes. A gel forms immediately. Comparative Sample C demonstrates the inability of a stabilizer compound which contains polyether chains having a high proportion of polymerized ethylene oxide to form a stable dispersion.