US4281089A
Expired / Lapsed
US
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Polyurethane compositions and process
Assignee: Uniroyal Chemical Co Inc
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Filing: 1980-09-08
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Granted: 1981-07-28
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Expires: 2000-09-08
Abstract
Abstract Polyurethane prepolymers having free isocyanate groups are treated with polyfunctional isocyanate-blocking agents to cause branching prior to or simultaneously with the addition of a curing diol. The composition containing the curing diol is molded in a conventional equipment at a conventional temperature, e.g., 100°-120°C. The resulting shaped article can be demolded in a fraction of the time required in the absence of the blocking agent. The shaped article is then post-cured within a temperature range of about 25°-150° C., during which time the curing diol, if present in sufficient amount, displaces the blocking agent and forms a cured, linear polyurethane. A typical suitable blocking agent is a substantially uncrosslinked phenol/formaldehyde resin. The curable composition can be prepared in one step from the diisocyanate, glycol, and blocking agent; and a composition containing all the components, including the curing diol, can be prepared in one or more steps. If a nonbasic blocking agent is used in the presence of the curing diol, it is recommended to use a tertiary amine catalyst to selectively catalyze the blocking, rather than the curing, reaction. The cured linear polyurethanes have good physical properties, comparable with those of the prior art polyurethane elastomers. Partly crosslinked cured polyurethanes find utility where resistance to organic liquids is important.
Inventors
- 👤 Jose F. Pazos
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 11:41
CPC Classifications
C; C08; C08G; C08G18/00; C08G18/06; C08G18/70; C08G18/72; C08G18/80; C08G18/8003; C08G18/08; C08G18/10; C08G18/28; C08G18/40; C08G18/54; C08G18/542
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
112 words
A curable polyurethane prepolymer composition consisting essentially of a reaction product of the following components (A) and (C) with (B): (A) 1 mole of a polymeric glycol having a number average molecular weight of about 400-3000; (B) at least 1.3 moles of an organic diisocyanate; and (C) a blocking agent having at least three active hydrogen groups per molecule capable of reacting with isocyanate groups, the proportion of the blocking agent being about 0.01 to 0.15 active hydrogen equivalent per equivalent of isocyanate groups in excess of hydroxyl groups. with the proviso that when the blocking agent is a phenol/aldehyde resin, its proportion is at most 5% by weight of component (A).
Claim 2
Dependent Claim
112 words
A curable polyurethane prepolymer composition consisting essentially of a reaction product of the following components (A) and (C) with (B): (A) 1 mole of a polymeric glycol having a number average molecular weight of about 400-3000; (B) at least 1.3 moles of an organic diisocyanate; and (C) a blocking agent having at least three active hydrogen groups per molecule capable of reacting with isocyanate groups, the proportion of the blocking agent being about 0.01 to 0.15 active hydrogen equivalent per equivalent of isocyanate groups in excess of hydroxyl groups. with the proviso that when the blocking agent is a phenol/aldehyde resin, its proportion is at most 5% by weight of component (A).
Claim 3
Dependent Claim
57 words
A composition of claim 1 which is one of the following: (1) a reaction product of a mixture of components (A) and (C) with (B), (2) a reaction product of component (A) with a reaction product of components (B) and (C), (3) a reaction product of component (C) with a reaction product of components (A) and (B).
Claim 4
Dependent Claim
19 words
A composition of claim 1 wherein the proportion of the diisocyanate is 1.5-6 moles per mole of polymeric glycol.
Claim 5
Dependent Claim
18 words
A composition of claim 3 wherein the polymeric glycol has a number average molecular weight of about 600-2000.
Claim 6
Dependent Claim
13 words
A composition of claim 4 wherein the polymeric glycol is polytetramethylene ether glycol.
Claim 7
Dependent Claim
28 words
A composition of claim 1 wherein the diisocyanate is selected from the group consisting of 4,4-methylenebis(phenyl isocyanate), 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, and mixtures of 2,4- and 2,6-tolylene diisocyanates.
Claim 8
Dependent Claim
21 words
A composition of claim 1 wherein the blocking agent is a substantially uncrosslinked phenol/aldehyde resin having at least three hydroxyl groups.
Claim 9
Dependent Claim
13 words
A composition of claim 7 wherein the phenol/aldehyde resin is a phenol/formaldehyde resin.
Claim 10
Dependent Claim
43 words
A composition of claim 1 also containing a diol having aliphatic hydroxyl groups and a molecular weight of less than about 250, the amount of the diol being equivalent to about 75-120% of the diisocyanate (B) in excess of the polymeric glycol (A).
Claim 11
Dependent Claim
26 words
A composition of claim 9 wherein the amount of the diol is equivalent to 90-105% of the diisocyanate (B) in excess of the polymeric glycol (A).
Claim 12
Dependent Claim
243 words
A process for making cured polyurethane elastomer articles, said process comprising the following two steps: (1) the following composition is blended together and molded at a sufficiently high temperature to crosslink the prepolymer, thereby to impart to the shaped article adequate mechanical integrity to permit the article to be demolded prior to complete cure: (A) 1 mole of a polymeric glycol having a number average molecular weight of about 400-3000; (B) at least 1.3 moles of an organic diisocyanate; (C) about 0.01 to 0.15 equivalent of an isocyanate-blocking agent having at least three active hydrogen groups per equivalent of isocyanate groups in excess of hydroxyl groups; with the proviso that when the blocking agent is a phenol/aldehyde resin, its proportion is at most 5% by weight of component (A); and (D) a diol having aliphatic hydroxyl groups and a molecular weight of less than about 250, the amount of the diol being equivalent to at least 75%, but no more than about 120%, of the diisocyanate (B) in excess of the polymeric glycol (A); and (2) the crosslinked molded article is demolded and maintained at a temperature of about 25°-150° C. until cure is completed; with the proviso that, instead of a mixture of components (A), (B), (C), and (D), one can use a mixture of (D) or of (D) and one of (A) and (C) with the product of a one-step or a two-step reaction of the remaining components with one another.
Claim 13
Dependent Claim
243 words
A process for making cured polyurethane elastomer articles, said process comprising the following two steps: (1) the following composition is blended together and molded at a sufficiently high temperature to crosslink the prepolymer, thereby to impart to the shaped article adequate mechanical integrity to permit the article to be demolded prior to complete cure: (A) 1 mole of a polymeric glycol having a number average molecular weight of about 400-3000; (B) at least 1.3 moles of an organic diisocyanate; (C) about 0.01 to 0.15 equivalent of an isocyanate-blocking agent having at least three active hydrogen groups per equivalent of isocyanate groups in excess of hydroxyl groups; with the proviso that when the blocking agent is a phenol/aldehyde resin, its proportion is at most 5% by weight of component (A); and (D) a diol having aliphatic hydroxyl groups and a molecular weight of less than about 250, the amount of the diol being equivalent to at least 75%, but no more than about 120%, of the diisocyanate (B) in excess of the polymeric glycol (A); and (2) the crosslinked molded article is demolded and maintained at a temperature of about 25°-150° C. until cure is completed; with the proviso that, instead of a mixture of components (A), (B), (C), and (D), one can use a mixture of (D) or of (D) and one of (A) and (C) with the product of a one-step or a two-step reaction of the remaining components with one another.
Claim 14
Dependent Claim
13 words
A process of claim 11 wherein the molding temperature is about 100°-120° C.
Claim 15
Dependent Claim
19 words
A process of claim 11 wherein the proportion of the diisocyanate is 1.5-6 moles per mole of polymeric glycol.
Claim 16
Dependent Claim
25 words
A process of claim 13 wherein the proportion of the curing diol is equivalent to 90-105% of the diisocyanate in excess of the polymeric glycol.
Claim 17
Dependent Claim
11 words
A process of claim 11 wherein the diisocyanate is methylenebis(4,4'-phenyl isocyanate).
Claim 18
Dependent Claim
22 words
A process of claim 15 wherein the isocyanate blocking agent is a substantially uncrosslinked phenol/formaldehyde resin having at least three hydroxyl groups.
Claim 19
Dependent Claim
40 words
The process of claim 11 wherein a nonbasic blocking agent (C) and the diol (D) are present in the blend of step (1) at the same time, and a tertiary amine catalyst is used to selectivity catalyze the isocyanate-blocking reaction.
Claim 20
Dependent Claim
27 words
A process of claim 17 wherein the amount of the catalyst is about 0.001-0.5% based on the combined weights of polymeric glycol (A) and organic diisocyanate (B).
Claim 21
Dependent Claim
21 words
A process of claim 18, wherein the proportion of the catalyst is 0.003-0.1% of the combined weights of (A) and (B).
Claim 22
Dependent Claim
27 words
A process of claim 11 wherein the proportion of diol (D) is sufficient to displace substantially all of the blocking agent from the blocking agent-diisocyanate reaction product.
Claim 23
Dependent Claim
27 words
A process of claim 11 wherein the proportion of diol (D) is insufficient to displace substantially all of the blocking agent from the blocking agent-diisocyanate reaction product.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-07-27 | 1985-01-26 | 1985-07-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-07-27 | 1989-01-26 | 1989-07-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-07-27 | 1993-01-26 | 1993-07-28 | $7700.00 | Window Closed / Lapsed |