Polyurethane sealant based on poly(butylene oxide) polyols for glass sealing

Abstract

A polyurethane glass sealant is made by reacting a poly(1,2-butylene oxide) polymer with a chain extender and a polyisocyanate. The poly(1,2-butylene oxide) polymer may be used as a mixture with up to 50% by weight of other polyols, including castor oil. The sealant is especially useful as a secondary sealant for an insulated glass unit (IGU).

Claims

1. A process for forming a seal between glass and a substrate, comprising: a) forming a curable reaction mixture by combining ingredients including 1) a poly(1,2-butylene oxide) polyol having a hydroxyl equivalent weight of at least 500 or a mixture of 50 to 99% by weight of a poly(1,2-butylene oxide) polyol having a hydroxyl equivalent weight of at least 500 with 1 to 50% by weight of at least one other polyol selected from (i) polymers and copolymers of propylene oxide having an equivalent weight of at least 300 and (ii) a hydroxyl-containing fat or oil, wherein component 1) has an average nominal functionality of at least 2.2 hydroxyl groups per molecule; 2) at least one chain extender and 3) at least one organic polyisocyanate, wherein the isocyanate index is 70 to 130; b) applying the curable reaction mixture to an interface between said glass and said substrate and in contact with both said glass and said substrate; c) curing the curable reaction mixture to form an elastomeric seal between the glass and the substrate.

2. A process for producing an edge seal for a multi-pane glass assembly, wherein the multi-pane glass assembly comprises at least one pair of substantially parallel glass sheets, the glass sheets of said pair being separated from each other by one or more spacers positioned between the pair of glass sheets at or near at least one edge of the glass a) applying a curable reaction mixture to said at least one edge of the pair of glass sheets and into contact with each of the pair of glass sheets and the spacer(s) separating said pair of glass sheets and b) curing the curable reaction mixture to form an elastomeric edge seal between the pair of glass sheets and adherent to the spacer(s) separating the pair of glass sheets; wherein the curable reaction mixture contains 1) a poly(1,2-butylene oxide) polyol having a hydroxyl equivalent weight of at least 500 or a mixture of 50 to 99% by weight of a poly(1,2-butylene oxide) polyol having a hydroxyl equivalent weight of at least 500 with 1 to 50% by weight of at least one other polyol selected from (i) polymers and copolymers of propylene oxide having a hydroxyl equivalent weight of at least 300 and (ii) a hydroxyl-containing fat or oil, wherein component 1) has an average nominal functionality of at least 2.2 hydroxyl groups per molecule; 2) at least one chain extender and 3) at least one organic polyisocyanate, and wherein the isocyanate index is 70 to 130.

3. The process of claim 2, wherein the poly(1,2-butylene oxide) polyol preferably has a nominal functionality of 2 to 2.5 and an equivalent weight per hydroxyl group of 800 to 1500.

4. The process of claim 3, wherein the poly(1,2-butylene oxide) has an average nominal hydroxyl functionality of at least 2.2 and is the only polyol having a hydroxyl equivalent weight of 200 or more in the reaction mixture.

5. The process of claim 2 wherein component 1) is a mixture of 70 to 95% by weight of the poly(1,2-butylene oxide) polymer and 5 to 30% by weight of castor oil.

6. The process of claim 5 wherein component 1) is mixture of 85 to 95% by weight of the poly(1,2-butylene oxide) polymer and 5 to 15% by weight of castor oil.

7. The process of claim 6 wherein the chain extender is 1,4-butane diol or 1,3-propane diol.

8. The process of claim 7, wherein the reaction mixture is devoid of a plasticizer.

9. The process of claim 7, wherein the reaction mixture contains 10 to 13% by weight of a plasticizer, based on the combined weight of the plasticizer and all reactive materials provided to the reaction mixture.

Description

EXAMPLES 1-4

(1) Example 1 is prepared as follows: A polyol blend is prepared by mixing 50 parts of a 2000 molecular weight difunctional poly(1,2-butylene oxide) homopolymer, and 50 parts a 3000 molecular weight nominally trifunctional poly(1,2-propylene oxide) homopolymer. To this blend are added 4.5 parts 1,4-butanediol and about 0.04 parts of a tin catalyst. This blend is mixed with a 143 isocyanate equivalent weight liquid MDI product at an isocyanate index of 1.02 to form a reaction mixture. The resulting cured elastomer contains 25.2% hard segment. The reaction mixture is compression molded at 50 C. for 30 minutes under an applied pressure of 20,000 psi (about 140 MPa) for 30 minutes. Tensile strength and elongation are measured according to ASTM 1708, and are as reported in Table 1 below. Results are as indicated in Table 1.

(2) Examples 2-6 are made in the same manner, except in each case the 1,4-butanediol is replaced with another chain extender, as indicated in Table 1. The amount of chain extender and the hard segment content of the elastomers are as indicated in Table 1. For Examples 3-6, the Shore A hardness is measured according to ASTM D2240.

(3) TABLE-US-00001 TABLE 1 Example Chain Extender, Hard Segment Tensile Strength, Shore A No. amount (parts) Content, % MPa (psi) Elongation, % Hardness 1 1,4-butanediol, 4.5 25.2 4.07 (590) 324 ND 2 2,2,4-trimethyl pentane-1,3-diol, 6.5 25.5 1.72 (250) 485 ND 3 2-ethyl hexane diol, 6.5 25.5 1.71 (248) 505 30 4 1,2-propane diol, 4 25.4 2.65 (384) 538 35 5 1,3-propane diol, 4 25.4 1.74 (252) 539 31 6 N,N-bis(2-hydroxylpropyl)aniline, 8 25.2 340 (234) 450 40

(4) When used to seal the edge of a multi-pane glass assembly, each of Examples 1 through 6 demonstrates excellent adhesion to the glass and spacer, and forms a high quality seal.

EXAMPLES 7-11

(5) Example 7 is prepared by mixing 70 parts of a 2000 molecular weight difunctional poly(1,2-butylene oxide) homopolymer with 30 parts castor oil. To this blend are added 1.5 parts 1,4-butanediol and 0.04 parts of a tin catalyst. The amount of 1,4-butanediol is selected so that the resulting cured elastomer contains 25% hard segment when cured at a 1.1 isocyanate index. This mixture is then combined with a 143 isocyanate equivalent weight liquid MDI product at an isocyanate index of 1.1 to form a reaction mixture, which is cured as described with respect to Examples 1-6. Tensile strength, elongation and Shore A hardness are measured as before, with results as are indicated in Table 2 below.

(6) Samples of the cured films are cut into dog-bones for evaluating the effect of water immersion on mechanical properties. The initial weight (W.sub.0) of the films is determined. The film is in each case then immersed for 24 hours in DI water maintained at 25 C. or in boiling water for 1 hour. After the specified time, the film is then dried with a tissue to remove surface water and weighed to obtain weight W.sub.1. The water absorption is calculated using equation:
Water uptake=(W.sub.1W.sub.0)/W.sub.0)100%

(7) Examples 8-11 are prepared and tested in the same manner, except the ratio of poly(1,2-butylene oxide) homopolymer and castor oil is varied as indicated in Table 2.

(8) TABLE-US-00002 TABLE 2 Mechanical Properties Poly(BO)/ Water Tensile Ex. Castor Oil uptake, Strength, Elongation, Shore A No. Ratio.sup.1 wt-% MPa (psi) % hardness 7 70/30 0.69 2.41 (350) 295 55 8 75/25 0.72 2.05 (297) 294 50 9 80/20 0.79 1.86 (270) 236 50 10 85/15 0.81 1.92 (279) 450 39 11 90/10 0.92 1.57 (227) 445 33 .sup.1The weight ratio of the poly(butylene oxide) diol and the castor oil in the formulation.

(9) When used to seal the edge of a multi-pane glass assembly, each of Examples 7 through 11 demonstrates excellent adhesion to the glass and spacer, and forms a high quality seal.

EXAMPLE 12

(10) A sealant composition is made and cured in the general manner described in the previous examples. The formulation is 85 parts of a 2000 molecular weight difunctional poly(1,2-butylene oxide) homopolymer, 15 parts castor oil, 1.5 parts of 1,4 butanediol, 0.05 parts of tin catalyst and 26.3 parts of the 143 equivalent weight liquid MDI. The resulting elastomer is cured at 50 C. for three days. Its tensile strength is about 200 MPa (290 psi) and its elongation is about 440. The water uptake is 0.8% by weight.

(11) Moisture Vapor Transmission Rates (MVTR) are analyzed on a MOCON Permatran-W 3/33 Water vapor permeability instrument. Standards that apply to the instrument include ASTM F-1249, TAPPI T557 and JIS K-7129. The moisture vapor transmission rate is 1.6 g/(100 in.sup.2/day) (0.103 g/m.sup.2/day).

(12) Oxygen Transmission Rates (OTR) are analyzed on a MOCON Oxtran 2/21 instrument. Standards that apply to the instrument include ASTM D-3985, ASTM F-1927, DIN 53380, JIS K-7126 and ISO CD 15105-2. The oxygen transmission rate is 80 mL/(100 in.sup.2/day) (5.16 mL/m.sup.2/day).

(13) The moisture vapor transmission and oxygen transmission values indicate the suitability of this elastomer for use as a secondary sealant in an IGU.

EXAMPLES 13-18

(14) Example 13 is prepared by mixing 85 parts of a 2000 molecular weight difunctional poly(1,2-butylene oxide) homopolymer with 15 parts of castor oil. To this blend are added 1.5 parts of 1,4-butanediol and 0.04 parts of a tin catalyst. 50 Parts of trimethyl pentanyl diisobutyrate (TXIB plasticizer from Eastman Chemicals) are added, as are 268.5 parts of calcium carbonate particulates, 2 parts of a silane adhesion promoter, 2 parts of an antioxidant and 5 parts by weight of a color paste. The resulting mixture is then combined with 24.4 parts of a 143 isocyanate equivalent weight liquid MDI product to form a reaction mixture, which is cured as described with respect to Examples 1-6. Tensile strength, elongation and Shore A hardness are measured as before, with results as are indicated in Table 3 below.

(15) Examples 14-18 are prepared and tested in the same manner, except the amount of plasticizer is varied as indicated in Table 3.

(16) TABLE-US-00003 TABLE 3 Mechanical Properties Plasticizer Tensile Ex. parts by Strength, Elongation, Shore A No. weight MPa (psi) % hardness 13 50 4.00 (580) 168 65 14 45 2.85 (414) 248 62 15 40 2.81 (408) 308 60 16 30 2.93 (425) 328 60 17 20 2.00 (291) 260 38 18 10 1.87 (271) 277 35

(17) When used to seal the edge of a multi-pane glass assembly, each of Examples 13 through 18 demonstrates excellent adhesion to the glass and spacer, and forms a high quality seal.

(18) All of these formulations have viscosities low enough to process easily even though many of them, especially Example 18, contain only a small amount of plasticizer and have high filler levels.