CA1253288A - Abrasion resistant thin polyurethane coatings - Google Patents
Abrasion resistant thin polyurethane coatingsInfo
- Publication number
- CA1253288A CA1253288A CA000429929A CA429929A CA1253288A CA 1253288 A CA1253288 A CA 1253288A CA 000429929 A CA000429929 A CA 000429929A CA 429929 A CA429929 A CA 429929A CA 1253288 A CA1253288 A CA 1253288A
- Authority
- CA
- Canada
- Prior art keywords
- aliphatic
- polyurethane
- diisocyanate
- crosslinking agent
- article according
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Landscapes
- Paints Or Removers (AREA)
- Laminated Bodies (AREA)
- Polyurethanes Or Polyureas (AREA)
Abstract
Abstract of the Disclosure A thin, abrasion resistant polyurethane coating which is hydroyl-tically and oxidatively stable is disclosed. The polyurethane coating is prepared by reacting a low molecular weight polycarbonate diol with an aliphatic diisocyanate, and curing with a trifunctional crosslinking agent.
The polyurethane coatings of the invention are particularly useful in aircraft transparencies.
The polyurethane coatings of the invention are particularly useful in aircraft transparencies.
Description
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ABRASION RESISTANT THIN POLYURETHAN~ COATINGS
Background of the Invention Field of the Invention . .
The present invention relates generally to abrasion resistant polyurethane coatings, and more particularly to thin polyurethane coatings which are both hydrolytically and oxidatively stable.
Discussion of Current Technology U.S. Patent No. 4,079,160 to Phillipson teaches an optical ele-ment, such as an eyeglass lens, formed of a typical rigid polymeric sub-strate of relatively low scratch resistance coated on at least one surface with a relatively soft, resilient and tough, transparent polymeric material.
U.S. Patent ~o. 4,174,240 to Muller teaches laminates wherein glass or glass-like plastics are coated ~ith a transparent film 0.1 to 5 millimeters thick formed from a polyurethane polyurea containing 1 to 20 percent by weight urea groups and 0.001 to 10 percent by weight lateral -COOH groups.
Summary of the Invention The present invention involves the use of relatively soft, resili-ent, crosslinked polyurethanes as abrasion resistant coatings. The poly-urethanes of the present invention are prepared from aliphatic diisocyanates, straight chain polycarbonate diols, and crosslinking agents such as triols, triamines and/or triisocyanates. The crosslinked aliphatic polycarbonate urethane coatings of the present invention are less than 0.005 inch (0.13 3~
millimeter) thick9 preferably about 0.002 inch (0.05 millimeter), thick.
The polyurethane coatings of the present invention are especially useful in aircraft transparencies as abrasion resistant coatings either on rigid plastic layers such as polycarbonate or acrylic, or an resilient plastic layers such as impact resistant polyurethane in a glass bilayer laminate.
Description of the Preferred ~mbodlments An abrasion resistant, crosslinked aliphatic polyurethane is pre-pared from a reaction mixture of an aliphatic organic diisocyanate, a poly-carbonate diol, and an aliphatic triol, triamine and/or triisocyanate. The polycarbonate diol preferably has a molecular weight below 500. Tetrabutyl titanate catalyst is also preferred in accordance with U.S. Patent No.
4,160,853. The reaction mixture may also comprise a chain extender, such as an aliphatic diol having up to about 12 carbon atoms.
The diisocyanate is preferably a cycloaliphatic diisocyanate such as 4,4'-methylene-bis-(cyclohexyl isocyanate). Polyurethane prepared from aliphatic isocyanates, particularly cycloaliphatic diisocyanates, have good physical and optical properties over a wide temperature range, and are not adversely affected by ultraviolet light. In addition to the most preferred diisocyanate, 4'4'-methylene-bis-(cyclohexyl isocyanate), other suitable ali-phatic diisocyanates include 1,4-cyclohexyl diisocyanate, 4,4-isopropylidene-bis-(cyclohexyl isocyanate), and other dinuclear cycloaliphatic diisocya-nates, preferably isophorone diisocyanate. Branched diisocyanates such as trimethylhexamethylene diisocyanate may also be used, preferably in com-bination with 4,4'-methylene-bis-(cyclohexyl isocyanate) or isophorone diisocyanate.
3~
Polyols useful according to the present invention may be liquid at room temperature or soluble in the reaction mixture. Preferred polyols are polycarbonate diols having a molecular weight of about 200 to 500. The polycarbonate diols are preferably synthesized in accordance with the teachings of U.S. Patent No. 4,160,853. Polycarbonate diols are preferred over polyether or other polyester polyols which may produce polyurethanes with less oxidative and hydrolytic stability.
The aliphatic diisocyanate and polyol are preferably mixed together under vacuum in a reaction kettle until the reaction mixture is slngle phase and well degassed. The reaction mixture further comprises a catalyst, preferably the tetrabutyl titanate which is present in the polycarbonate diol synthesized by the preferred method disclosed above. The catalyst is preferably present at a level of about 100 to 1000 parts per million.
The diisocyanate and polycarbonate diol are reacted in appropriate proportions to form either an OH-terminated or an NCO-terminated prepolymer.
The prepolymer is then crosslinked to form an abrasion-resistant polyure-thane by means of a triisocyanate, triamine or triol crosslinking agent. In an alternatlve embodiment9 the polyol, diisocyanate and crosslinking agent may be added together in a one-shot polymerization reaction mixture.
The polyurethane reaction mixture is preferably in solution in any solvent for the reactants, preferably methyl ethyl ketone, propylace-tate, toluene, cyclohexanone and mixtures thereof. The reaction solution dries to form a coating less than about 0.005 inch (0.13 millimeter) thick, pr~ferably about 0.001 to 0.002 inch (about 0.025 to 0.05 millimeter) thick.
The polyurethane is typically cured at temperatures from about 225 to 275F
(about 107 to 135C) 9 preferably about 250 to 275F (about 121 to 135DC), for about 1 hour or l~nger to yield an abrasion resistant coating.
.~
3~
The present invention will be more fully understood from the descriptions of specific examples which follow.
EXAMPLE I
A polycarbonate diol is prepared by reacting 1,6-hexanediol with diethyl carbonate to for~ an average five unit oligomer. A hydroxy-terminated prepolymer is prepared by reacting 57 weight percent of the 1,6-hexanediol based polycarbonate diol with 43 weight percent 4,4'-methylene-bis-~cyclohexyl isocyanate), available as Hylene W from E. I.
du Pont de Nemours & Co., Inc., Wilmington, Delaware. A polyurethane is prepared by reacting 81 weight percent of the prepolymer with 19 weight percent of a triisocyanurate of isophorone diisocyanate, in a solvent com-prising equal weights of toluene and cyclohexanone totaling about 3 times the weight of the reactants. The reaction mixture is coated onto a rigid polycarbonate sheet and cured for 1 1/2 hours at 250 F (about 121 C) to form an abrasion resistant polyurethane coating.
EXAMPLE II
A polyurethane reaction mixture is coated onto a preformed thermoplastic polyurethane sheet which is subsequently laminated to a glass sheet to form a bilayer laminate. The polyurethane reaction mixture com-prises 78 weight percent of the prepolymer as in ~xample I, 22 weight percent of a triisocyanate biuret of 1,6-hexamethylene diisocyanate, and three times the weight of these reactants of a solvent comprising equal weights of toluene and cyclohexanone. The reaction mixture is dried and cured during the lamination process to form a thin, abrasion-resistant crosslinked polyurethane coating on the thermoplastic polyurethane surface ~ ~rad~ a~k 33~Bi;~
of the bilayer laminate. The lamination process is described in detail in U. S. Patent No. 3,808,079 to Rieser et al.
The above examples are offered to illustrate the present inven tion. Various modifications, such as the coating of other substrates, the use of other components, applying and curing by other means, etc. are included within the scope of the present invention, which is defined by the following claims.
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ABRASION RESISTANT THIN POLYURETHAN~ COATINGS
Background of the Invention Field of the Invention . .
The present invention relates generally to abrasion resistant polyurethane coatings, and more particularly to thin polyurethane coatings which are both hydrolytically and oxidatively stable.
Discussion of Current Technology U.S. Patent No. 4,079,160 to Phillipson teaches an optical ele-ment, such as an eyeglass lens, formed of a typical rigid polymeric sub-strate of relatively low scratch resistance coated on at least one surface with a relatively soft, resilient and tough, transparent polymeric material.
U.S. Patent ~o. 4,174,240 to Muller teaches laminates wherein glass or glass-like plastics are coated ~ith a transparent film 0.1 to 5 millimeters thick formed from a polyurethane polyurea containing 1 to 20 percent by weight urea groups and 0.001 to 10 percent by weight lateral -COOH groups.
Summary of the Invention The present invention involves the use of relatively soft, resili-ent, crosslinked polyurethanes as abrasion resistant coatings. The poly-urethanes of the present invention are prepared from aliphatic diisocyanates, straight chain polycarbonate diols, and crosslinking agents such as triols, triamines and/or triisocyanates. The crosslinked aliphatic polycarbonate urethane coatings of the present invention are less than 0.005 inch (0.13 3~
millimeter) thick9 preferably about 0.002 inch (0.05 millimeter), thick.
The polyurethane coatings of the present invention are especially useful in aircraft transparencies as abrasion resistant coatings either on rigid plastic layers such as polycarbonate or acrylic, or an resilient plastic layers such as impact resistant polyurethane in a glass bilayer laminate.
Description of the Preferred ~mbodlments An abrasion resistant, crosslinked aliphatic polyurethane is pre-pared from a reaction mixture of an aliphatic organic diisocyanate, a poly-carbonate diol, and an aliphatic triol, triamine and/or triisocyanate. The polycarbonate diol preferably has a molecular weight below 500. Tetrabutyl titanate catalyst is also preferred in accordance with U.S. Patent No.
4,160,853. The reaction mixture may also comprise a chain extender, such as an aliphatic diol having up to about 12 carbon atoms.
The diisocyanate is preferably a cycloaliphatic diisocyanate such as 4,4'-methylene-bis-(cyclohexyl isocyanate). Polyurethane prepared from aliphatic isocyanates, particularly cycloaliphatic diisocyanates, have good physical and optical properties over a wide temperature range, and are not adversely affected by ultraviolet light. In addition to the most preferred diisocyanate, 4'4'-methylene-bis-(cyclohexyl isocyanate), other suitable ali-phatic diisocyanates include 1,4-cyclohexyl diisocyanate, 4,4-isopropylidene-bis-(cyclohexyl isocyanate), and other dinuclear cycloaliphatic diisocya-nates, preferably isophorone diisocyanate. Branched diisocyanates such as trimethylhexamethylene diisocyanate may also be used, preferably in com-bination with 4,4'-methylene-bis-(cyclohexyl isocyanate) or isophorone diisocyanate.
3~
Polyols useful according to the present invention may be liquid at room temperature or soluble in the reaction mixture. Preferred polyols are polycarbonate diols having a molecular weight of about 200 to 500. The polycarbonate diols are preferably synthesized in accordance with the teachings of U.S. Patent No. 4,160,853. Polycarbonate diols are preferred over polyether or other polyester polyols which may produce polyurethanes with less oxidative and hydrolytic stability.
The aliphatic diisocyanate and polyol are preferably mixed together under vacuum in a reaction kettle until the reaction mixture is slngle phase and well degassed. The reaction mixture further comprises a catalyst, preferably the tetrabutyl titanate which is present in the polycarbonate diol synthesized by the preferred method disclosed above. The catalyst is preferably present at a level of about 100 to 1000 parts per million.
The diisocyanate and polycarbonate diol are reacted in appropriate proportions to form either an OH-terminated or an NCO-terminated prepolymer.
The prepolymer is then crosslinked to form an abrasion-resistant polyure-thane by means of a triisocyanate, triamine or triol crosslinking agent. In an alternatlve embodiment9 the polyol, diisocyanate and crosslinking agent may be added together in a one-shot polymerization reaction mixture.
The polyurethane reaction mixture is preferably in solution in any solvent for the reactants, preferably methyl ethyl ketone, propylace-tate, toluene, cyclohexanone and mixtures thereof. The reaction solution dries to form a coating less than about 0.005 inch (0.13 millimeter) thick, pr~ferably about 0.001 to 0.002 inch (about 0.025 to 0.05 millimeter) thick.
The polyurethane is typically cured at temperatures from about 225 to 275F
(about 107 to 135C) 9 preferably about 250 to 275F (about 121 to 135DC), for about 1 hour or l~nger to yield an abrasion resistant coating.
.~
3~
The present invention will be more fully understood from the descriptions of specific examples which follow.
EXAMPLE I
A polycarbonate diol is prepared by reacting 1,6-hexanediol with diethyl carbonate to for~ an average five unit oligomer. A hydroxy-terminated prepolymer is prepared by reacting 57 weight percent of the 1,6-hexanediol based polycarbonate diol with 43 weight percent 4,4'-methylene-bis-~cyclohexyl isocyanate), available as Hylene W from E. I.
du Pont de Nemours & Co., Inc., Wilmington, Delaware. A polyurethane is prepared by reacting 81 weight percent of the prepolymer with 19 weight percent of a triisocyanurate of isophorone diisocyanate, in a solvent com-prising equal weights of toluene and cyclohexanone totaling about 3 times the weight of the reactants. The reaction mixture is coated onto a rigid polycarbonate sheet and cured for 1 1/2 hours at 250 F (about 121 C) to form an abrasion resistant polyurethane coating.
EXAMPLE II
A polyurethane reaction mixture is coated onto a preformed thermoplastic polyurethane sheet which is subsequently laminated to a glass sheet to form a bilayer laminate. The polyurethane reaction mixture com-prises 78 weight percent of the prepolymer as in ~xample I, 22 weight percent of a triisocyanate biuret of 1,6-hexamethylene diisocyanate, and three times the weight of these reactants of a solvent comprising equal weights of toluene and cyclohexanone. The reaction mixture is dried and cured during the lamination process to form a thin, abrasion-resistant crosslinked polyurethane coating on the thermoplastic polyurethane surface ~ ~rad~ a~k 33~Bi;~
of the bilayer laminate. The lamination process is described in detail in U. S. Patent No. 3,808,079 to Rieser et al.
The above examples are offered to illustrate the present inven tion. Various modifications, such as the coating of other substrates, the use of other components, applying and curing by other means, etc. are included within the scope of the present invention, which is defined by the following claims.
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Claims (21)
IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method for making a hydrolytically and oxidatively stable, abrasion resistant polyurethane comprising the steps of:
a. reacting an aliphatic diisocyanate with a polycarbonate diol having a molecular weight less than 500; and b. curing said reaction poroduct with a crosslinking agent selected from the group consisting of aliphatic triols, triamines, triisocyanates and mixtures thereof to form a crosslinked polyurethnne.
a. reacting an aliphatic diisocyanate with a polycarbonate diol having a molecular weight less than 500; and b. curing said reaction poroduct with a crosslinking agent selected from the group consisting of aliphatic triols, triamines, triisocyanates and mixtures thereof to form a crosslinked polyurethnne.
2. The method according to claim 1, wherein the aliphatic diisocyanate is a cycloaliphatic diisocyanate in such proportion with the polycarbonate diol as to form a hydroxy-terminated prepolymer, and the crosslinking agent is a triisocyanate.
3. The method according to claim 1, wherein the aliphatic diisocyanate is a cycloaliphatic diisocyanate in such proportion with the polycarbonate diol as to form an isocyanate-terminated prepolymer and the crosslinking agent is a triol.
4. The method according to claim 2, wherein the cycloaliphatic diisocyanate is 4,4'-methylene-bis-(cyclohexyl isocyanate).
5. The method according to claim 3, wherein the cycloaliphatic diisocyanate is 4,4'-methylene-bis-(cyclohexyl isocyanate).
6. The method according to claim 4 or 5, wherein the polycarbonate diol is represented by the formula wherein x is from about 4 to 12 and y is from 1 to about 4.
7. The method according to claim 1, wherein the reaction occurs in solution.
8. The method according to claim 7, wherein the solvent is selected from the group consisting of methyl ethyl ketone, propylacetate, toluene, cyclohexanone and mixtures thereof.
9. A polyurethane prepared according to the method of claim 1.
10. A polyurethane prepared according to the method of claim 2.
11. A polyurethane in accordance with claim 9, wherein said polyurethane forms a coating less than 0.005 inch (about 0.13 millimeter) thick.
12. An abrasion resistant coated article comprising a rigid transparent substrate and a crosslinked polycarbonate urethane costing.
13. An article according to claim 12, wherein the rigid transparent substrate is selected from the group consisting of acrylic, polycarbonate and polyurethane sheets.
14. An article according to claim 12, wherein the rigid transparent substrate is a laminate comprising a sheet of glass and a layer of thermoplastic polymer.
15. An article according to claim 14, wherein the thermoplastic polymer is an energy-absorbing polyurethane.
16. An article according to claim 12, wherein the crosslinked polycarbonate urethane is prepared from an aliphatic diisocyanate, a polycarbonate diol having a molecular weight less than 500 and a crosslinking agent selected from the group consisting of aliphatic triols, triamines and triisocyanates.
17. An article according to claim 13, wherein the crosslinked polycarbonate urethane is prepared from an aliphatic diisocyanate, a polycarbonate diol having a molecular weight less than 500 and a crosslinking agent selected from the group consisting of aliphatic triols, triamines and triisocyanates.
18. An article according to claim 14, wherein the crosslinked polycarbonate urethane is prepared from an aliphatic diisocyannte, a polycarbonate diol having a molecular weight less than 500 and a crosslinking agent selected from the group consisting of aliphatic triols, trinmines and triisocyanates.
19. An article according to claim 15, wherein the crosslinked polycarbonate urethane is prepared from an aliphatic diisocyanate, a polycarbonnte diol having a molecular weight less than 500 and a crosslinking agent selected from the group consisting of aliphatic triols, triamines and triisocyanates.
20. An article according to claim 16, 17 or 18 wherein the aliphatic diisocyanate is 4,4'-methylene-bis-(cyclohoxyl isocyanate).
21. An article according to claim 19, wherein the aliphatic diisocyanate is 4,4'-methylene-bis-(cyclohexyl isocyanate).
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US39461082A | 1982-07-02 | 1982-07-02 | |
| US394,610 | 1982-07-02 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1253288A true CA1253288A (en) | 1989-04-25 |
Family
ID=23559693
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000429929A Expired CA1253288A (en) | 1982-07-02 | 1983-06-08 | Abrasion resistant thin polyurethane coatings |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1253288A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107180670A (en) * | 2017-07-14 | 2017-09-19 | 天津威利安电工器材有限公司 | A kind of TF application types high-frequency and high-voltage heavy in section product enamelled stranded-wire and preparation method |
-
1983
- 1983-06-08 CA CA000429929A patent/CA1253288A/en not_active Expired
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107180670A (en) * | 2017-07-14 | 2017-09-19 | 天津威利安电工器材有限公司 | A kind of TF application types high-frequency and high-voltage heavy in section product enamelled stranded-wire and preparation method |
| CN107180670B (en) * | 2017-07-14 | 2022-11-25 | 天津威利安电工器材有限公司 | TF coating type high-frequency high-voltage large-section area enameled stranded wire and manufacturing method |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |