AU611706B2

AU611706B2 - Storage-stable hydrocurable oxazolidine-isocyanate compositions

Info

Publication number: AU611706B2
Application number: AU20324/88A
Authority: AU
Inventors: John James Theodore
Original assignee: Minnesota Mining and Manufacturing Co
Current assignee: 3M Co
Priority date: 1988-07-26
Filing date: 1988-08-02
Publication date: 1991-06-20
Anticipated expiration: 2008-08-02
Also published as: AU2032488A; JPH0255715A; CA1336469C

Description

Cl .2 5845/2 ii S F Ref: 67050 S F Ref: 67050 FORM COMMONWEALTH OF AUSTRAUA PATENTS ACT 1952 COMPLETE SPECIFICATION

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FOR OFFICE USE: Complete Specification Lodged: Accepted: ~Published: Priority: Related Art: Class Int Class *0 *r V #0

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Name and Address of Applicant: Address for Service' Minnesota Mining and Manufacturing Company 3M Center Saint Paul Minnesota 55144-1000 UNITED STATES OF AMERICA Spruson Ferguson, Patent Attorneys Level 33 St Martins Tower, 31 Market Street Sydney, New South Wales, 2000, Australia Complete Specification for the invention entitled: Storage-Stable Hydrocurable Oxazolidine-Isocyanate Compositions The following statement Is a full description best method of performing it known to me/us of this invention, including the 5845/3 Saint Paul, Declared at Minnesota,

U.S.A.

this 6th day of July 19 88 Signature of DeclararII(s) Donald Miller Sell Chief Patent Counsel 98 To: The Commissioner of Patents 9/31 SFP3 42352 AUS 7A STORAGE-STABLE HYDROCURABLE OXAZOLIDINE-ISOCYANATE

COMPOSITIONS

Abstract A one-part, storage-stable moisture-curable composition useful as an adhesive, coating and sealant comprising a urethane oxazolidine and an aromatic polyfunctional isocyanate.

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COMPOSITIONS

Technical Field This invention relates to one-part, storage-stable, moisture-curable adhesive, coating, and sealant compositions comprising a defined oxazolidine and a polyfunctional 9se o aromatic isocyanate.

*Background Art 15 Moisture-curable, isocyanate terminated, urethane a. prepolymers have long been used in formulating adhesive, coating and sealant products. The reactions of such compounds with atmospheric moisture are often catalyzed by addition of tertiary amines or tin salts to increase the cure rate. A 20 by-product of the reaction is carbon dioxide, which when generated in sufficient quantity, can create voids in the cured polymer. As one way to overcome this problem, oxazolidine compounds have been utilized as curing agents or co-reactants. (See, U.S. Patent Nos. 3,661,923, 25 3,743,626, 4,138,545, and 4,002,601).

S" The use of oxazolidine compounds in one-compotnent, moisture curable urethane compositions has generally been limited to systems using aliphatic isocyanates. (See, e.g., U.S. Patent Nos. 3,912,691, 4,024,117, 4,381,388 and 4,417,102.) The art has taught that the storage life of systems which include aromatic polyisocyanates is very brief.

(See U.S. Patent No. 4,118,376, for example.) The use of blends of aromatic isocyanates and oxazolidines is stated to be "not attractive if long pot-life of the blend is required" in Journal of Coatings Techology, 49, 65, 1977, and to "offer only one or two days of pot-life", Preprints of I; 1 -2- Division of Organic Coatings and Plastics, 167th Meeting of the American Chemical Society, April 1974, page 739.

Storage-stability, or pot-life, of six months or greater is desirable, and a composition having such a would be considered storage-stable. However, the irse of aliphatic isocyanates to attain same is not desirable because of typically slow cure times and considerable expense.

It is therefore desirable to provide a storage stable, moisture curable composition which utilizes an aromatic isocyanate.

Summary of the Invention It has surprisingly been found that aromatic 15 isocyanate compounds can be used in combination with certain types of oxazolidine compounds to produce storage-stable, hydrocurable, one-part compositions useful as adhesives, coatings or sealants. The storage-stable, hydrocurable, one-part composition of the present invention comprises a e "20 urathane oxazolidine and an aromatic polyfunctional isocyanate. The urethane oxazolidine is preferably a urethane bisoxazolidine.

C 9 Detailed Description Of The Invention The urethane oxazolidine compounds of the invention may be any organic compound having at least one, 'and preferably two or three, groups of the following formula: 2 N- R4 -0-C-NH- R R wherein: I en,' au 4* 0 *Z a *I 0a 9) a a £0 @0 0 a.

-3- R1 represents an aliphatic hydrocarbon group having from 2 to 6, preferably 2 or 3, carbon atoms; R2 and R3 may be the same or different and represent hydrogen, aliphatic hydrocarbon groups having 1 to 4 carbon atoms, cycloaliphatic hydrocarbon groups having 5 to 7 carbon atoms, or aromatic hydrocarbon groups having 6 to 10 carbon atoms or, together with the ring carbon atom, they may represent a five-membered ring. R2 and R3 are preferably the same or different groups and are hydrogen or aliphatic hydrocarbon groups having from 1 to 4 carbon atoms, 15 R4 represents an aliphatic hydrocarbon group having from 2 to 6 carbon atoms; R5 represents a group which is obtained by removal of the isocyanate groups from an organic isocyanate, preferably a di- or triisocyanate; and n represents an integer of from 1 to 6, preferably 2 or 3.

Such oxazolidines have been described, for example, in U.S. Patent No. 4,002,601 and numerous examples are 25 provided therein.

Hydrolytic ring opening of these oxazolidlnes results in the formation of one hydroxyl group and one secondary amino group per oxazolidine ring so that even oxazolidines having only a single oxazolidine ring are converted by reaction with water into compounds which are difunctional for the purpose of the isocyanate addition reaction. However, it is preferred to use urethane oxazolidines containing two oxazolidine rings (bisoxazolidine) for greater cross-link density in the final -4cured product, such as in particular N,t U-bJs-( (2-isopropyl- 1, 3-oxazolidin-3-yl )-ethoxycarbonyl 3-1, 6-diaminohexane.

A suitable commercially available urethane bisoxazolidine is "Hardner OZ",1 baied on aliphatic poly(amino-alcohol), commercially available from Mobay Chemical Corporation.

it is theorized that these oxazolidines are capable of providing the desired pot life because they are nonacidic, free acids being capable of promoting the opening of 1the oxazolidine ring prematurely.

Any organic aromatic polyisocyanates may be used :for the preparation of the prepolymers, with isocyanate groups such as diphenylmethane-2,4'-diisocyanate and/or 4,4'-diisocyanate; tolylene-2,4-diisocyanate and *we 15 -2,6-diisocyanate and mixtures of these isomers being ~.exemplary. Other examples inclu'de: diisocyanate; triphenylmiethane-4,4',4"1-triisocyanate; phenylene-l,3-diisacyrana~e and -1,4-diisocyanate, dimethyl- 3,3'-biphenylene-4,4'-diisocyanatue; diphenylisopropylidine- 4,41-diisocyanate; biphenylene diisocyanate; xylylene-l,3dilsocyanate and -1,4-diisocyanate.

A list of useful commercial~ly available polyisocyanates is found in the "Encyclopedia of Chemical Technology," Kirk-Othmer, 2nd Ed., Vol. 12, pp. 46-47, Interscience Pub~., N.Y. (1967). Preferable isocyanates include diphenylmethane-4,4'-diisocyanate (MDI) and tolylene-2,4-diisocyanate/tolylene-2,6-diisocyanate(TDI)and mixtures of these isomers.

Also, isocyanate-functional derivative(s) of MDI and TDI may be used, such as liquid mixtures of the isocyanate-functional derivative with melting point modifiers mixtures of MDI with polycarbodiimide adducts such as "Isonate 143L"I, commercially available from the Upjohn Co., and "Mondur CD"I, commercially available from Mobay Chemical Corp. polymeric diphenylmethane diisocyanates "PAPI". and the series "PAPI 20" through "PAPI 901"1, commercially available from the Upjohn Co., "Mondur MR", "Mondur MRS", and "Mondur MRS-10", commercially available from Mobay Chemical Corp., and "Rubinate commercially available from Rubicon Chemicals, Inc.); and blocked isocyanate compounds formed by reacting aromatic isocyanates or the above-described isocyanate-functional derivatives with blocking agents such as ketoximes and the like. Such blocked isocyanate compounds will, for convenience, be regarded herein as isocyanate-functional derivatives of MDI or TDI.

Suitable polyols for use in this invention include polytetramethylene oxide glycols, ethylene oxide-terminated polypropylene oxide poly!ols, polypropylene oxide polyols, Spolyethylene oxide polyols, hydroxy-termiated S' polybutadienes, aliphatic glycols, polyester polyols 15 polyacrylate polyols or polycaprolactone polyols), fatty alcohols, and triglycerides castor oil) such as are described in U.S. Pat. No. 4,511,626. Mixtures of polyols can also be used.

Because of their hydrolytic stability in the cured 20 compositions of the invention, preferred classes of polyols are polypropylene oxide polyols, ethylene oxide-terminated polypropylene oxide polyols, and polytetramethylene oxide glycols, particularly those having a number average molecular weight from about 500 to 6000. Suitable commercially S* 25 available polytetramethylene oxide glycols include the "QO Polymeg" 650, 1000, or 2000 series, commercially available from Quaker Oats Co., and "Terat t ie" 650, 1000, or 2000 series, commercially available from E.I. du vont de Nemours Co., Inc. Suitable commercially available polypropylene oxide polyols include the "Niax" series "PPG", "LHT", and "LHG" commercially available from Union Carbide Corp. Ethylene oxide terminated polypropylene oxide polyols are commercially available as the "Poly G" series, available from Olin Chemicals.

The equivalent ratio of oxazolidine to isocyanate preferably should be from about 0.1 to about 1.2 to -6- Decreasing quantities of oxazolidine reduce the effectiveness of carbon dioxide suppression, while increasing quantities result in excess unreacted oxazolidine, which can lead to a reduction in strength of th2 cured composition, excessive tackiness and a gummy consistency, all undesirable characteristics.

The compositions of the invention can contain other ingredients or adjuvants if desired. For example, extenders or reinforcing fillers carbon black, metal oxides such as zinc oxide, and minerals such as talc, clays, silica, silicates, and the like) may be included to impart particular characteristics to the composition.

Plasticizers such as partially hydrogenated S* terphenyls "HB-40", commercially available from ee 1 5 Monsanto Corp.), alkylsulfonic ester of phenol "Mesamoll", commercially available from Mobay Chemical Corp.), dioctyl phthalate, dibutyl phthalate, diisodecyl phthalate, or tri-cresyl phosphate can also be employed in the compositions of the invention.

20 Solvents such as toluene, xylene, methyl ethyl ketone, acetone, ethyl acetate, mineral spirits and VM and P I, naphtha and other suitable materials free of isocyanatereactive moieties can be employed in the compositions of the invention.

25 In addition, the compositions can contain antioxidants, pigments, UV absorbers, adhesion promoters silanes such as mercapto silanes or aminosilanes or tackifying resins such as terpenephenolics), drying agents molecular sieves such as sodium aluminum silicate or such as zeolite) and the like.

The prepolymers of the invention are made using conventional methods. Typically, they are prepared by reacting an excess of one or more polyisocyanates with one or more polyols to produce a prepolymer having residual functionality.

-7- The compositions of the invention when properly compounded have utility as adhesives, coatings, and sealants and can be applied to a variety of articles and substrates, such as articles or substrates of glass, metal, plastic, wood, leather, masonary, textiles, and the like. They find particular utility where low shrinkage, void free compositions are required such as sealing concrete joints.

The invention is further described by the following non-limiting examples wherein all parts are by weight unless otherwise specified.

Example 1 A composition of the invention was prepared by S* adding to a reaction vessel, fitted with a nitrogen inlet and 15 a thermometer, 16.49 parts (13.2 NCO equivalents) of flake MDI, 21.06 parts (1.0 OH equivalent) polypropylene oxide polyol ("Niax LHT-28", Union Carbide). Mixing was started and the mixture was heated to 60 0 C. Then, 52.45 parts (5.2 OH equivalents) polytetramethylene ether glycol, MW 2000 20 ("Polymeg 2000", Quaker Oats Co.) and 10.0 parts partially hydrogenated terphenyl Monsanto Corp.) were added.

The mixture was held at 601C for 3 hours then cooled to about and stored in a sealed container.

To 535 parts of this prepolymer were added, under 6 25 nitrogen and with stirring, 50 parts fumed silica ("Cab-O-Sil T!-720", Cabot Corp.), 40 parts titanium dioxide, 160 parts talc ("Mistron RCS", Cyprus Industrial Minerals parts gamma-mercaptopropyltrimethoxy silane ("Silane A-189", Union Carbide), 100 parts alkylsulphonic ester of phenol ("Mesatoll", Mobay Chemical Corp.), 47.3 parts urethane bisoxazolidine ("Hardner OZ", Mobay Chemical Corp.), and parts to uene. The resultant product was transfered to conventional plastic caulking cartridges. The sealant was dispensible using a manual caulking gun, and in the plastic containers, the composition maintained a caulkable viscosity in excess of six months when stored at about 25 0

C.

-8- Example 2 A composition of the invention was prepared by adding to a reaction vessel fitted with a nitrogen inlet, stirrer and thermometer, 10.72 parts (19.7 NCO equivalents) of an 80:20 mixture of tolylene-2,4-diisocyanate and tolylene-2,6-diisocyanate and 9.99 parts toluene, 21.03 parts (3.3 OH equivalents) polypropylene oxide glycol, MW 2000, ("Niax Polyol PPG-2025", Union Carbide) and 58.19 parts (6.6 OH equivalents) polypropylene oxide polyol ("Niax LHT-42", Union Carbide) with stirring. The reaction mixture was slowly heated to about 80 0 C and held there for about 3 hours then cooled to about 52°C. Then, 0.07 part dibutyltin dilaurate was added and mixing and cooling continued for about 1 hour.

15 The resultant prepolymer was stored in a sealed container.

To 45.6 parts of this prepolymer were added, under nitrogen and with stirring, 2.7 parts titanium dioxide; 2.7 parts zinc oxide; 20.7 parts talc; 0.06 part carbon black ("Raven 410", Cities Service 8.3 parts terpenephenolic 20 resin ("Piccofyn A-135", Hercules); 1.9 parts fumed silica; parts urethane bisoxazolidine; 1.1 parts silane S. containing primer (prepared by mixing 1610 g. biuret of hexamethylene diisocyanate ("Desmodur N-75", Mobay Chemical 427 g. silane and 1.3 g. dimethylpiperazine in a three 25 liter four inlet resin flask equipped with mechanical stirrer, reflux condenser, and nitrogen supply, for two hours at 80 0 C with stirring), and 15.2 parts 1-methoxy-2-acetoxy propane.

This composition was applied as a sealant to concrete. The composition was poured into a gap of 1.5 cm between blocks, 15 1/2 cm x 5 1/2 cm x 5 cm, of aggregate concrete. The composition was cured at 25*C, 50% R.H, for 7 days, followed by 2 days at 49 0 C. The cured sealant was relatively free of voids when cut open and inspected.

-9- Example 3 and Comparative Examples 1-3 These examples illustrate the storage stability of the compositions of the invention utilizing a urethane bisoxazolidine versus the same prepolymer catalyzed with conventional urethane catalysts such as amines and tin salts.

Using the prepolymer of Example 1, four one-part moisture curable compositions were prepared and evaluated.

Example 3 was prepared with 8.54 parts of "Hardner OZ".

Comparative Example 1 was prepared with 0.2 part of "Niax A-99" (a tertiary amine catalyst, commercially available from Union Carbide Corp.). In Comparative Examples 2 and 3, 0.8 part and 0.1 part respectively of dibutyltin dilaurate (DBTDL) were added. Set out below in Tables 1-4 are the viscosity measurements after containers of samples had been 15 exposed to various temperatures. Measurements in ceiNtipoises (cps) were taken with a Brookfield RVF viscometer using a #6 spindle and speed of 4 RPM with sample temperature at about 23 0

C.

4 20 Example 3 prepolymer 8.54 parts Hardner OZ Comparative Example 1 prepolymer 0.2 part NIAX A-99 SComparative Example 2 prepolymer 0.8 part DBTDL Comparative Example 3 prepolymer 0.1 part DBTDI 46 Table 1 24 0 C Viscosity__(cps) Comp. Conip.

EJx. 3 Ex. 1 Ex. 2 Comp.

EX. 3 Ini tial 1 week 2 weeks 3 weeks 4 weeks weeks wek 6 weeks 7 weeks 18 weeks is. year 48,750 51,250 51,250 50, 000 52,500 55,000Q 51,250 56, 250 67,500 77, 500 130,000 50,000 55,000 51,875 50,000 52,500 55,000 53r750 57,500 67,500 77,500 120,000 50,000 61,250 75,625 96,250 143,750 2 3 1, 2 F0 375,000 500,100 0 gelled 50,000 50,000 52,500 53,750 51,200 53,750 57,500 56,250 75,000 165t000 i4~ 9 49 g 6 9 9* 4. 9.

9 9 9 9 49* 9 6 *9U~ .9 9 4, 9 Table 2 389C Viscosity__(cps), Cowpo Ex. 3 Ex.4 1 Comp.

Ex. 2 Comp Ex. 3 I, 49 9 4~ 9G.

9 *4 *6 96 4 4* 9. 4 4 6 94 Tnitial I. week 2 weeks 3 weeks 25 4 weeks 5 weeks 6 weeka 7 weeks 8 weeks 18 weeks 48,750 56,250 61t250 62,500 78,750 88,750 85,000 98,750 122,500 310,000 50,000 S6t25O 61,250 62,500 72,500 77,500 87,500 50,000 161,250 5 0 0,000 gelled 50,000 55,000 62,500 67,500 70,000 82,500 93,750 107,500 470,000 102,50 136,250_____ >500tO000 R1 represents an aliphatic hydrocarbon group having from 2 to 6, preferably 2 or 3, carbon atoms; R2 and R3 may be the same or different and represent hydrogen, aliphatic 4ydrocarbon groups having 1 to 4 carbon atoms, cycloaliphatic hydrocarbon groups having 5 to 7 carbon atoms, or aromatic hydrocarbon /2 IL- -11- Table 3 49CC Viscosity (cps) Camp.

Ex. 3 Ex. 1 Camp.

Ex. 2 Camp.

EX. 3 1 week 2 weeks 3 weeks 4 weeks 5 weeks 6 weeks 7 weeks 8 weeks 18 weeks 48,750 67,500 86, 250 112,000 140,000 180,000 193 750 235,000 290,000 5 0 0 00 50,000 65,000 68,750 75,000 9 1,f2 50 172,500 375,000 50 0 ,00 0 gelled 50"0 00 60,000 78,750 65,000 297,500 83,750 gelled 100,000 112,r50 0 162,500 185,000 2 25 0,j00 0

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Ex. 3 Ex 3 20 initial .1 week 2 weeks 3 weeks 4 weeks 25 5 weeks 6 weeks 7 weeks 8 weeks 18 weeks 48,750 82, 500 210,000 375,000 50 0 ,00 0 gelled 50,000 50,000 EQ,'000 72,500 gelled 88,750 131,250 181,250 gelled 390,000 _______gelled The composition performed better than or as of the well as invention, Comparative Example 3, Examples 1-3 at all temperatures tested. Furthermore, Compaivative Examples 1-3 all produced undesirable CO, gas, which will not allow formation of a void-free coating.

li.l -12- Comparative Example 4 This comparative example illustrates the decreased storage stability of compositions utilizing an adipate-based bisoxazolidine.

A moisture curable composition was prepared and evaluated as in Example 3 using the prepolymer of Example 1 and 6.83 parts (1 equivalent) of an adipate-based bisoxazolidine ("QM-1007", commercially available from Rohm and Haas Viscosity measurements are set out in Table below.

6666 6 6646 *6 0 6 69 *r 6 6*0O 66 6 6 *6 66 6 6 6 6 Table 5 Viscosity (cps)

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1 week 2 weeks 3 weeks 4 weeks 5 weeks 6 weeks 7 weeks 11 weeks 32,500 81,250 88,750 98,750 100,000 123,750 112,500 135,000 140,000 38 0

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82,500 131,250 132,500 178,750 265,000 352,000 395,000 485,000 >500,000 gelled 82,500 158,750 315,000 >500,000 gelled This example appears to support the theory that a bisoxazolidine capable of containing free acid exhibits decreased storage stability.

i 1 -1

Claims

1. A storage-stable, hydrocurable, one-part composition comprising a urethane oxazolidine and an aromatic polyfunctlonal isocyanate or Isocyanate prepolymer.

2. The composition of claim 1 wherein said urethane oxazolidine has the structural formula: R R n 2 3 wherein: R1 represents an allphatic hydrocarbon group having from 2 to 6, preferably 2 or 3, carbon atoms; R2 and R3 may be the same or different and represent hydrogen, aliphatic hydrocarbon groups having 1 to 4 carbon atoms, cycloaliphatic hydrocarbon groups having 5 to 7 carbon atoms, or aromatic hydrocarbon groups having 6 to 10 carbon atoms or, together with the ring carbon atom, they may represent a five-membered ring; R4 represents an aliphatic hydrocarbon group having from 2 to 6 carbon atoms; S R5 represents a group which is obtained by removal of the Isocyanate groups from an organic Isocyanate, preferably a di- or tri- Isocyanate; and 0 o** /13 Ppf "offer only one or two days of pot-life", Preprints of Ic~TS II El I 14 n represents an integer of from 1 to 6, preferably 2 or 3.

3. The composition of claim 1 wherein said orazolidine is a urethane bisoxazolidine. urethane 0**6 0 4 0 go r 0 0* 0 a 0 OS S 0S B0 *C S S S S V S. S) 0

4. The composition of claima 1 wherein the equivalent ratio of said oxazolidine to said isocyanate is between about 0.1 and 1.2 to

5. The composition of claim 4 wherein said eq:,ivalent ratio of said oxazolidine to said isocyanate is 10 between about 0.25 and 1.0 to

6. A polymeric urethane material formed by contacting a composition according to claim 1 with water.

7. The polymeric urethane material of claim 6 wherein said oxazolidine is a bisoxazolidine. 15

8. An article of manufacture comprising a substrate having a coating of said polymeric urethane material of claim 6 on at least a portion thereof.

9. A one part composition comprising a urethane oxazolidine and an aromatic polyfunctional isocyanate or isocyanate prepolymer substantially as described herein with reference to any one of the Examples other than comparative examples. A polymeric urethane material comprising the product of the composition of claim 9 contacted with water. DATED this FIRST day of AUGUST 1988 Minnesota Mining and Manufacturing Company Patent Attorneys for the Applicant SPRUSON FERGUSON