HK1093997B - Polyurethane dispersion (pud) with improved isopropanol resistance, flexibility and softness - Google Patents

Description

Polyurethane dispersions (PUD) with improved isopropanol resistance, flexibility and softness

Cross Reference to Related Applications

This application is a continuation-in-part application of U.S. patent application serial No. 10/419584 filed on 21/4/2003.

Technical Field

The present invention relates to isocyanate-functional polyurethane prepolymers and aqueous dispersions thereof, and to their use for producing flat (flat) materials.

Background

The general precautions taken worldwide to prevent HIV, hepatitis b and hepatitis c in the early nineties of the last century have resulted in a dramatic increase in the use of latex gloves and condoms. About 1% of glove users and about 10% of users working in the hygiene sector develop hypersensitivity sensitisation reactions and it has therefore become increasingly important in recent years to find a substitute for use in the detection of glove and condom parts.

Natural latex contains both type I and type IV allergens. The type I allergens may be due to proteins inherent in latex and may even cause anaphylactic shock. Type IV allergens are accelerators and additives required in latex production. These substances often lead to allergic contact dermatitis. As far as is known, polyurethanes do not produce the abovementioned allergic reactions. Therefore, there is a great need for aqueous polyurethane dispersions which can be processed analogously to latices to give the abovementioned hygiene articles.

According to the report in WO-A00/61654, aqueous polyurethane dispersions obtained from nonionic isocyanate prepolymers after addition of an anionic emulsifier and subsequent dispersion with water are suitable for the production of gloves and condoms. However, one disadvantage of these products is the use of anionic emulsifiers, which migrate out of the polymer during use and consequently adversely affect the use properties of the product. The products obtained according to WO-A00/61653 have the same limitations.

One major problem when polyurethane gloves are used in medicine, particularly in surgery, is the use of isopropyl alcohol containing mixtures in these articles to disinfect the gloved hand. The use of isopropyl alcohol entails the problem of swelling of the glove material, which generally reduces the mechanical resistance of the material, with consequent tearing of the glove.

A method for improving the isopropanol resistance of conventional commercial polyurethane dispersions by post-addition of a crosslinking component is described in us patent 5997969. However, the addition of crosslinking components is a technically demanding and expensive process for glove and condom manufacturers, since the mixing equipment required to achieve this is generally not commercially available. Such mixtures of reactive crosslinking agents and substrates have only a limited pot life. This is also an unresolved problem for glove and condom manufacturers, as the process usually follows the coagulation operation, and the coagulated batch is usually not consumed. It is generally replenished by repeated additions of fresh material.

European patent 741152 discloses NCO-functional polyurethane ("PU") prepolymers based on a polyol component which predominantly comprises polyoxypropylene diols having a low content of unsaturated units. The dispersions thus prepared are suitable for the production of flexible films and coatings. However, it has a disadvantage that the solvent resistance of the PU film is unsatisfactory.

Canadian patent 1089141 discloses mixtures of aromatic and aliphatic or cycloaliphatic polyisocyanates for the preparation of finely divided, stable aqueous dispersions of anionically modified polyurethanes. However, the isopropanol resistance of the flat materials prepared from them is likewise lacking.

Several additional references are described in U.S. patent No. 10/453755, filed on 3/6/2003, which relates to the use of polyurethane dispersions in medical articles. The invention described in patent application 10/453755 is an isocyanate functional prepolymer, aqueous polyurethane dispersions prepared from this prepolymer and various medical uses of such dispersions. The prepolymers described in this patent have an NCO content of from about 1 to about 6 weight percent and are prepared by reacting:

A) an organic diisocyanate in a mixture of at least one organic diisocyanate,

B) at least one dihydroxy compound having a number average molecular weight of about 700 to about 16000, and

C) with the general formula R- (OH)₃Wherein R is a saturated straight or branched chain aliphatic radical having 2 to 8 carbon atoms,

wherein the amount of component C) is such that the amount of hydroxyl groups from component C) is from about 2% to about 15% of the total amount of hydroxyl equivalents used to produce the prepolymer.

Disclosure of Invention

The object of the present invention was to provide NCO-functional prepolymers which are suitable for the production of polyurethane flat materials which have satisfactory solvent resistance and at the same time excellent minimum tear strength and minimum ultimate elongation and do not have the disadvantages described in the prior art.

The present invention provides a polyurethane prepolymer prepared by combining specific isocyanates and specific hydroxyl-containing compounds which meet specific criteria required to achieve this objective.

More particularly, the present invention relates to isocyanate functional prepolymers, aqueous polyurethane dispersions prepared from such prepolymers and various applications of these dispersions. The polyurethane prepolymer has an NCO content of about 1% to about 6% by weight (preferably 2-4%) and is prepared by reacting:

A) isocyanate selected from

i) An aliphatic and/or cycloaliphatic isocyanate, and,

ii) mixtures of aromatic isocyanates and aliphatic and/or cycloaliphatic isocyanates,

B) a dihydroxy or polyhydroxy compound having a number average molecular weight of 700 to about 16000, and

C) optionally, dihydroxy and/or polyhydroxy compounds having a number average molecular weight of less than 700,

the premise is that,

a) at least one of components A), B) or C) has a functionality of greater than 2, and

b) if both components A) and B) are difunctional, then component C) cannot be of the formula

R-(OH)₃

Wherein R is a saturated straight or branched chain aliphatic group having 2 to 8 carbon atoms.

Detailed Description

Suitable isocyanates include any organic compound having at least two free isocyanate groups per molecule, e.g., diisocyanate X (NCO)₂X represents a divalent aliphatic hydrocarbon group having 4 to 12 carbon atoms, a divalent alicyclic hydrocarbon group having 6 to 15 carbon atoms, a divalent aromatic hydrocarbon group having 6 to 15 carbon atoms orA divalent araliphatic hydrocarbon radical having 7 to 15 carbon atoms. Further examples of compounds suitable as diisocyanate component are described by W.Siefken, for example, Justus Liebig' sAnnalen der Chemie, 562, pages 75 to 136.

Specific examples of the diisocyanates to be used are tetramethylene diisocyanate, methylpentamethylene diisocyanate, 1, 6-hexamethylene diisocyanate, dodecamethylene diisocyanate, 1, 4-diisocyanatocyclohexane, 1-isocyanato-3, 3, 5-trimethyl-5-isocyanatomethylcyclohexane, 4' -phenylene diisocyanate, 2, 4-tolylene diisocyanate, 2, 6-tolylene diisocyanate, 4 ' -diphenylmethane diisocyanate, 2 ' -and 2, 4 ' -diphenylmethane diisocyanate, p-xylylene diisocyanate, p-isopropylidene diisocyanate, 1, 3-and 1, 4-diisocyanatomethylbenzene and mixtures of these compounds.

Particularly preferred are 1-isocyanato-3, 3, 5-trimethyl-5-isocyanatomethylcyclohexane; 1, 6-hexamethylene diisocyanate; 4, 4' -dicyclohexylmethane diisocyanate; 2, 4-and 2, 6-toluene diisocyanate or any mixture of these isomers; 4, 4 ' -, 2, 4 ' -and 2, 2 ' -diphenylmethane diisocyanate (MDI monomer) or any mixture of these isomers.

Also useful are what are known as polymeric MDI products, such as the polymeric MDI products obtained by aniline-formaldehyde condensation reaction followed by phosgenation (crude MDI), and the polymeric MDI products obtained by partially removing MDI monomers from these crude products by distillation.

Naturally, it is also possible to (co) use small amounts of the high-functional polyisocyanates known from polyurethane chemistry and of the modified polyisocyanates having carbodiimide groups, allophanate groups, isocyanurate groups, urethane groups and or biuret groups.

In a preferred embodiment, the isocyanate is a mixture containing from 5 to 50 wt%, preferably from 10 to 45 wt%, most preferably from 20 to 35 wt% of one or more aliphatic and/or cycloaliphatic diisocyanates and from 50 to 95 wt%, preferably from 55 to 90 wt%, most preferably from 65 to 80 wt% of one or more aromatic diisocyanates.

Suitable components B) are compounds having at least two hydroxyl groups and a number average molecular weight of from 700 to about 16000. Examples of such compounds are polyethers, polyesters, polycarbonates, polylactones and polyamides. Preferred compounds have 2 to 8 hydroxyl groups, most preferably 2 to 4 hydroxyl groups, such as are known for the preparation of homogeneous foamed polyurethanes and such as are described, for example, on pages 11 to 18 of German patent 2832253. Mixtures of different such compounds may also be used.

Linear polyesterdiols or weakly branched polyesterpolyols are suitable as polyesterpolyols which can be prepared by known methods from aliphatic, cycloaliphatic or aromatic dicarboxylic or polycarboxylic acids or their anhydrides (e.g.succinic, glutaric, adipic, pimelic, suberic, azelaic, sebacic, terephthalic, isophthalic, phthalic, tetrahydrophthalic, hexahydrophthalic or trimellitic acid) and anhydrides (such as anhydrides of phthalic, trimellitic or succinic acid or mixtures thereof) and polyhydric alcohols, for example ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1, 2-propanediol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, 1, 3-propanediol, 1, 4-butanediol, 1, 3-butanediol, 2, 3-butanediol, 1, 5-pentanediol, 1, 6-hexanediol, 2-dimethyl-1, 3-propanediol, 1, 4-dihydroxycyclohexane, 1, 4-dimethylolcyclohexane, 1, 8-octanediol, 1, 10-decanediol, 1, 12-dodecanediol, or a mixture thereof, optionally together with a high functional polyol such as trimethylolpropane or glycerol. Cycloaliphatic and/or aromatic dihydroxy and polyhydroxy compounds are, of course, also suitable as polyols for the preparation of the polyester polyols. Instead of the free polycarboxylic acids, it is also possible to use the corresponding polycarboxylic anhydrides or corresponding polycarboxylic esters of lower alcohols or mixtures thereof for preparing the polyesters.

The polyester polyols may also be homopolymers or copolymers of lactones, which are preferably obtained by addition reaction of lactones or lactone mixtures, such as butyrolactone,. epsilon. -caprolactone and/or methyl-. epsilon. -caprolactone, with suitable difunctional and/or higher-functional starter molecules, such as the low molecular weight polyhydric alcohols mentioned above as structural components of the polyester polyols. Preference is given to the corresponding polymers of epsilon-caprolactone.

Polycarbonates having hydroxyl groups are also considered suitable polyols. They can be prepared by reacting diols such as 1, 4-butanediol and/or 1, 6-hexanediol with diaryl carbonates such as diphenyl carbonate, dialkyl or phosgene.

Examples of suitable polyether polyols are polyaddition products of styrene oxides; polyaddition products of ethylene oxide, propylene oxide, tetrahydrofuran, butylene oxide and epichlorohydrin and their co-addition and graft products; polyether polyols obtained by polycondensation of polyols or mixtures thereof; and polyether polyols obtained by alkoxylation of polyols, amines and amino alcohols.

Preferred components B) are homopolymers, copolymers and graft polymers of propylene oxide and ethylene oxide, which are obtained by addition reaction of the specified epoxides with low molecular weight diols or triols, such as those specified above for the production of polyester polyols, or with high-functional low molecular weight polyols, such as pentaerythritol or sugars, or with water.

Particularly preferred components B) are polyether polyols based on one or more polyoxypropylene diols having a number average molecular weight of from about 1000 to about 8000 and an unsaturated end group content of less than or equal to 0.02 milliequivalents, preferably from 0.005 to 0.015 milliequivalents, per gram of polyol (determination method ASTM D2849-69 used), which are obtainable by known methods from the double metal cyanide complex-catalyzed (DMC-catalyzed) polymerization of alkylene oxides, preferably propylene oxide, as described, for example, in U.S. Pat. No. 5158922 (example 30) or in European patent 654302 (line 26 on page 5 or line 32 on line 6). Particularly preferred components B) are the compounds listed in Table 1 below.

TABLE 1

All ofThe polyol product is a commercial product available from Bayer AG of Leverkusen, Germany.

In a preferred embodiment of the present invention, component B) comprises at least 60% by weight of at least one polyoxypropylene diol.

Suitable components C) are dihydroxy and/or polyhydroxy compounds having a number average molecular weight of from 62 to less than 700. Polyols, especially diols, are specified for the preparation of polyester polyols having the desired molecular weight, as well as polyether diols, polyether triols and polyester diols. Suitable low molecular weight polyesters include, for example, bis (hydroxyethyl) adipate. Short-chain homo-and co-addition products of ethylene oxide or propylene oxide starting on aromatic diols may also be used. Preferred components C) are i) low molecular weight diols: 1, 2-ethanediol, 1, 4-butanediol, 1, 6-hexanediol and 2, 2-dimethyl-1, 3-propanediol, particularly preferably 1, 4-butanediol and 1, 6-hexanediol, and ii) low molecular weight polyether triols.

Addition products of alkylene oxides, such as propylene oxide or ethylene oxide, with aromatic dihydroxy compounds or aromatic dicarboxylic acids, such as hydroquinone, resorcinol, catechol or 2, 2-bis (4-hydroxyphenyl) propane (bisphenol a), may also be used.

The present invention also provides a process for preparing the prepolymers according to the invention having isocyanate groups, in which components A), B) and C) are reacted in such proportions that the isocyanate content is between 1 and 6% by weight, preferably between 2 and 4% by weight.

In general, the proportions of the components are such that the mathematical number average isocyanate functionality in the resulting prepolymer is between 2.1 and 3.6, preferably between 2.3 and 2.8. The preparation is carried out at a temperature in the range of 20-130 c, preferably between 50-120 c, most preferably between 70-105 c.

The prepolymers of the present invention can then be converted to aqueous dispersions. For this purpose, the prepolymers of the invention are reacted with amino-functional components D) and amine chain extenders E).

The invention also provides aqueous polyurethane dispersions comprising the prepolymers of the invention, and

D) compounds containing one anionic or potentially anionic group and two groups reactive toward isocyanate groups and

E) at least one chain extender containing two amine groups reactive with isocyanate groups.

Suitable components D) are compounds which comprise one anionic group or one group capable of forming an anionic group (potentially anionic group) and two groups reactive toward isocyanate groups, for example diamino compounds which comprise one carboxylate or sulfonate group as anionic group or one carboxylic or sulfonic group as potentially anionic group. Preferred components D) are diamines or polyamines which contain alkali metal sulfonate groups, for example alkali metal salts of N- (2-aminoethyl) -2-aminoethanesulfonic acid. Particularly preferred is the sodium salt.

The free carboxylic or sulfonic acids can of course also be added to the isocyanate polyaddition reaction. Then, before being converted into a polyurethane resin in water, neutralization must be carried out with a neutralizing agent, examples of which are alkali metal hydroxides, alkali metal bicarbonates, alkali metal carbonates or tertiary amines, such as triethylamine, diisopropylethylamine, triisopropylamine, N-dimethylethanolamine, triethanolamine or triisopropanolamine.

Compounds suitable as chain extenders E) are aliphatic and/or cycloaliphatic primary and/or secondary diamines, for example 1, 2-ethylenediamine, 1, 6-hexamethylenediamine, 1-amino-3, 3, 5-trimethyl-5-aminomethylcyclohexane (isophoronediamine), piperazine, 1, 4-diaminocyclohexane, bis (4-aminocyclohexyl) methane, adipic acid dihydrazide or hydrazine. Polyetherdiamines which can be prepared by reacting the corresponding polyetherdiols with ammonia and/or primary amines are also usable. However, 1-amino-3, 3, 5-trimethyl-5-aminomethylcyclohexane (isophoronediamine) and 1, 2-ethylenediamine are particularly preferred as chain extender E).

The aqueous preparations of the polyurethane resins on which the dispersions of the invention are based are generally prepared by d.dieterich in Houben-Weyl: prepared by the method described in Methoden der Organischen Chemie, Vol.E 20, p.1670-1681 (1987). The process known as the "acetone process" is preferred. In this process, the aqueous preparation on which the dispersion is based, which comprises the prepolymer of the invention, is synthesized in a multistage process.

In a first step, the prepolymer of the invention is dissolved in an at least partially water-miscible organic solvent which does not contain isocyanate-reactive groups. The preferred solvent is acetone. However, other solvents such as 2-butanone, tetrahydrofuran, dioxane, N-methylformamide, N-methylacetamide or N-methylpyrrolidone may also be used, either directly or in small portions. The amount used is generally such that the solids content is from 20 to 80% by weight, preferably from 30 to 50% by weight.

The prepolymer solution is then reacted with a mixture of amino-functional components D) and E), preferably dissolved in one of the above solvents or water, to give a high molecular weight polyurethane resin with chain extension. The amounts of the components are such that 0.3 to 0.93 mol, 0.65 to 0.85 mol of NH in components D) and E) are present per mole of isocyanate groups in the dissolved prepolymer₂The groups are present. Furthermore, component D) containing anionic groups or groups capable of forming anionic groups is used in such an amount that 19 to 70 milliequivalents of ions per 100 g of solids, preferably per 100 g of solids, are present in the resulting polyurethaneThe solids correspond to 20-35 milliequivalents of ions.

When component D) having free carboxylic or sulfonic acid groups is used, the acid groups are neutralized with a neutralizing agent in a proportion of from 50 to 100 equivalent%, relative to the free acid groups, before the addition of the water required for dispersion.

The high molecular weight polyurethane resin is precipitated as a finely divided dispersion by adding water to the solution. Optionally the organic solvent is completely or partially distilled off under reduced pressure. The amount of water used is such that the resulting aqueous dispersion contains from 30 to 60% by weight, preferably from 35 to 50% by weight, of solids.

The aqueous dispersions of the invention have an average particle diameter (measured by laser correlation spectroscopy) of from 50 to 300 nm, preferably from 60 to 150 nm, and are stable for storage for at least 6 months.

The dispersions of the invention can be processed by customary methods to give films, foils, surface coatings, lacquers and also for impregnating a wide variety of substrates. The dispersions are preferably suitable for the production of films, most preferably for the manufacture of polyurethane gloves and condoms by the dipping or solid processes.

The present invention provides an isopropanol resistant polyurethane film. The prepolymers of the present invention are preferably used to make polyurethane gloves and condoms.

The polyurethane dispersions of the invention may also contain, depending on their intended use, customary auxiliaries and additives, for example crosslinking agents, plasticizers, pigments, defoamers, soft-feel additives or fillers.

The aqueous dispersions of the invention can also be used in combination with other dispersions, for example polyacrylate dispersions, natural and artificial latices, such as NBR (nitrile-butadiene rubber), chloroprene or other homopolymers and copolymers, such as ethyl vinyl acetate or ethyl vinyl alcohol.

The flat materials produced from the polyurethane dispersions of the invention have satisfactory solvent resistance and have excellent minimum tear strength and minimum ultimate elongation.

The invention is further illustrated but is not to be limited by the following examples in which all parts and percentages are by weight unless otherwise specified.

Examples

Examples 1 to 5

General description of preparation of polyurethane Dispersion films

The aqueous dispersion was applied to a glass plate with a 1000 micron doctor blade and should be free of bubbles or foam. The coating is pre-dried at room temperature for 16-24 hours. The clear film was then post-dried in a circulating air drying cabinet at 80 ℃ for 1 hour. The film was then left at room temperature for at least 5 hours. After the film had been removed from the glass plate, the film was punched out to give the test specimens required in each case.

Determination of the alcohol resistance of polyurethane Dispersion films

The dimensions of the test specimens are measured in mm

Total length: 75.0

Front (head) width: 12.5

Test piece (web) length: 25.0

Width of sample piece: 4.0

Thickness: about 0.2

The test specimens were stored at room temperature for 24 hours. Then, a mark was made on each of the left and right sides of the sample piece, with a distance of about 50 mm between the marks. The test specimen was then stretched to 100% and fixed in this state. The test sample under tension was wetted by dropping 2 drops of isopropanol at the center of the two marks. If the sample is damaged, it does not have alcohol resistance.

The particle size was measured by laser correlation spectroscopy (measuring apparatus: Malvern Instruments Zetasizer 1000).

Example 1

(comparative example) example 1 corresponding to Canadian patent 1089141

203 g of a polyester prepared from adipic acid, hexanediol and neopentyl glycol and having an OH number of 55 mg KOH/g were dewatered at 110 ℃ and 120 ℃ and 30 mbar for 30 minutes. The polyester was cooled, dissolved in 200 g of acetone and 40.5 g of 1, 4-butanediol were added. Then a mixture of 69.7 g of toluene diisocyanate (isomer ratio 2, 4/2, 6 ═ 80/20) and 69.7 g of hexamethylene diisocyanate and 0.02 g of dibutyltin dilaurate was added. After stirring for 3 hours at 60 ℃, the batch is diluted with 300 g of acetone and cooled to room temperature. 19.3 g of a 40% aqueous solution of an equimolar addition product of ethylenediamine and sodium acrylate were added to the prepolymer solution thus obtained with stirring. After 20 minutes, 500 g of water was added dropwise, and the acetone was distilled off under reduced pressure. A very finely divided, stable dispersion is obtained.

When the PU flat material prepared from this dispersion was treated with isopropanol, the material was torn, thus demonstrating that the material was not alcohol-resistant.

Ion content [ milliequivalents/100 g ] ═ 14.3

The components used were:

2200N, 4200N, 6300 and PPG 1000 polyols andv218 polyols, which are commercially available from Bayer AG, Leverkusen, Germany.

1.TABLE 2: polyol component

2. An isocyanate component:

toluene diisocyanate, TDI 80: isomer ratio 2, 4/2, 6 ═ 80/20,

NCO functionality 2

1-isocyanato-5- (isocyanatomethyl) -1, 3, 3-trimethylcyclohexane: IPDI, isophorone diisocyanate

Other components:

AAA salt: sodium salt of N-2-aminoethane-2-aminosulfonic acid, 45% concentration, water as solvent

1, 4-butanediol

Ethylene diamine

Water (W)

Example 2: (according to the invention)

446.4 g2200N polyol

167.0 g6300 polyol

26.1 g of 1, 4-butanediol

39.4 g of 1-isocyanato-5- (isocyanatomethyl) -1, 3, 3-trimethylcyclohexane (IPDI)

115.6 g of toluene diisocyanate (TDI80)

1770.0 g of acetone

75.6 grams AAA salt

0.4 g of ethylenediamine

1640.0 grams of partially deionized water

446.4 grams of2200N polyol and 167.0 g6300 the polyol is dehydrated at 110-120 ℃ for 1 hour at 30-50 mbar. The mixture was then cooled to 90 ℃ and stirred with 26.1 g of 1, 4-butanediol for 5 minutes, to which 39.4 g of IPDI and 115.6 g of TDI80 were then added. After stirring at 95 to 105 ℃ for 7 hours, an isocyanate (NCO) content of 3.04% (theoretical NCO ═ 3.04%), isocyanate group-terminated prepolymer was obtained. The prepolymer was cooled to about 60 ℃ and 1770 g of acetone was added with stirring. An amine chain extender solution prepared from 75.6 grams of AAA salt and 0.4 grams of ethylenediamine in 113 grams of water was added to the clear, homogeneous prepolymer solution at about 50 ℃. The solution thus became cloudy and the viscosity increased slightly. After 15 minutes, 1640 g of partially deionized water were added over 30 seconds with rapid stirring. After about 200 ml of water, a low viscosity dispersion was formed. The acetone was then distilled off under vacuum caused by water jet at 50 ℃.

A stable, finely divided dispersion having an average particle diameter of 84 nm was obtained. The solids content of the dispersion was 33.6% and the Ford viscosity cup value (4 mm spray) was 18 s/25 ℃.

The dispersion was applied to a glass plate with a doctor blade to form a film. The films were first dried at room temperature and then dried in a circulating air drying cabinet at 80 ℃ for 1 hour.

The resulting film was transparent and elastic and resistant to isopropanol.

Ion content [ milliequivalents/100 g ] ═ 21.6

Example 3: (according to the invention)

216.2 g2200N polyol

445.4 grams PPG 1000

23.5 gV218 polyol

43.5 g of 1-isocyanato-5- (isocyanatomethyl) -1, 3, 3-trimethylcyclohexane (IPDI)

125.4 g of toluene diisocyanate (TDI80)

1653.0 g of acetone

76.1 grams AAA salt

0.3 g of ethylenediamine

1826.0 grams of partially deionized water

216.2 g of the powder2200N polyol, 445.4 g PPG 1000 and 23.5 gThe V218 polyol is dehydrated for 1 hour at 110-120 ℃ and 30-50 mbar. The mixture was then cooled to 90 ℃ and 43.5 g IPDI and 125.4 g TDI80 were added. After stirring at 95 to 105 ℃ for about 7 hours, an isocyanate (NCO) content of 2.89% (theoretical NCO ═ 3.08%), isocyanate group-terminated prepolymer was obtained. The prepolymer was cooled to about 60 ℃ and 1653 grams of acetone were added with stirring. An amine chain extender solution prepared from 76.1 grams of AAA salt and 0.3 grams of ethylenediamine in 114 grams of water was added to the clear, homogeneous prepolymer solution at about 50 ℃. The solution thus became cloudy and the viscosity increased slightly. After 15 minutes, 1826 g of partially deionized water were added over 30 seconds with rapid stirring. After about 200 ml of water, a low viscosity dispersion was formed. The acetone was then distilled off under vacuum caused by water jet at 50 ℃.

A stable, finely divided dispersion having an average particle diameter of 65 nm was obtained. The solids content of the dispersion was 33.8% and the Ford viscosity cup value (4 mm spray) was 48 s/25 ℃.

The dispersion was applied to a glass plate with a doctor blade to form a film. The films were first dried at room temperature and then dried in a circulating air drying cabinet at 80 ℃ for 1 hour.

The resulting film was transparent and elastic and resistant to isopropanol.

Ion content [ milliequivalents/100 g ] ═ 20.3

Example 4: (according to the invention)

544.1 g2200N polyol

176.0 g6300 polyol

29.2 g of 1-isocyanato-5- (isocyanatomethyl) -1, 3, 3-trimethylcyclohexane (IPDI)

84.9 g of toluene diisocyanate (TDI80)

1619.0 g of acetone

75.1 grams AAA salt

0.8 g of ethylenediamine

1787.0 grams of partially deionized water

544.1 g2200N and 176.0 g6300 the polyol is dehydrated at 110-120 ℃ for 1 hour at 30-50 mbar. Then theThe mixture was cooled to 90 ℃ and then 29.2 g IPDI and 84.9 g TDI80 were added. After stirring at 95 to 105 ℃ for about 7 hours, an isocyanate (NCO) content of 2.90% (theoretical NCO ═ 3.06%), isocyanate group-terminated prepolymer was obtained. The prepolymer was cooled to about 60 ℃ and 1619 grams of acetone was added with stirring. An amine chain extender solution prepared from 75.1 grams of AAA salt and 0.8 grams of ethylenediamine in 113 grams of water was added to the clear, homogeneous prepolymer solution at about 50 ℃. The solution thus became cloudy and the viscosity increased slightly. After 15 minutes, 1787 g of partially deionized water were added over 30 seconds with rapid stirring. After about 200 ml of water, a low viscosity dispersion was formed. The acetone was then distilled off under vacuum caused by water jet at 50 ℃.

A stable, finely divided dispersion having an average particle diameter of 108 nm was obtained. The solids content of the dispersion was 34% and the Ford viscosity cup value (4 mm spray) was 30 s/25 ℃.

The dispersion was applied to a glass plate with a doctor blade to form a film. The films were first dried at room temperature and then dried in a circulating air drying cabinet at 80 ℃ for 1 hour.

The resulting film was transparent and elastic and resistant to isopropanol.

Ion content [ milliequivalents/100 g ] ═ 20.5

Example 5: comparative example

Corresponding to example 3 in European patent 741152

400 g4200N polyol

20.3 g dimethylolpropionic acid

122.5 g of 1-isocyanato-5- (isocyanatomethyl) -1, 3, 3-trimethylcyclohexane

12.3 g triethylamine

13.2 g of ethylenediamine

70.0 grams of fully deionized water

780.0 grams of fully deionized water

400.0 gThe 4200N polyol is dehydrated for 1 hour at 110-120 ℃ under 30-50 mbar. Then 20.3 g dimethylolpropionic acid were added and the mixture was stirred at 100 ℃ for 30 minutes. Then cooled to 90 ℃ and 122.5 g of 1-isocyanato-5- (isocyanatomethyl) -1, 3, 3-trimethylcyclohexane are added. The reaction was carried out at 100 ℃ until the isocyanate content was constant (theoretical 4.21% isocyanate). After cooling to 65 ℃, 12.3 g of triethylamine were added and stirred for a further 15 minutes. The prepolymer was poured, with thorough stirring, into 780 g of fully deionised water kept at a constant temperature of 50 ℃. After dispersion was complete, the chain length was increased by adding 13.3 grams of ethylenediamine in 70 grams of fully deionized water. Stirring was continued at 50 ℃ until the dispersion contained no isocyanate groups. A moderately dispersed stable dispersion was obtained.

Table 3:mechanical Properties and resistance to Isopropanol

Examples	100% modulus [ MPa ]]	Tensile strength [ MPa ]]	Ultimate elongation [% ]]	Resistance to isopropanol
					1 (comparative example)	1.1	5.9	850	Is free of
2	1.4	16.4	1310	Has tolerance property
					3	1.7	13.1	1100	Has tolerance property
4	1.4	11.6	1620	Has tolerance property
					5 (comparison example)	5.9	33.4	900	Is free of

Example 6: (according to the invention)

To a reactor equipped with a heating mantle, stirrer, nitrogen inlet, reflux condenser and addition funnel were added the following: 376.98 g of a polyester diol (OH number 66, prepared from adipic acid, hexanediol and neopentyl glycol) and 10.07 g of a polyether triol (trimethylolpropane/propylene oxide polyether, OH number 380, number average molecular weight 440). The stirrer was then started and the mixture was heated to 58 ℃. At this temperature 73.81 g of hexamethylene diisocyanate were added. The reaction mixture was exothermic and the temperature was raised to 75 ℃ and then maintained at 80 ℃ until an isocyanate content of 3.17% by weight (theoretical 3.36%) was reached. The mixture was diluted with 691.28 g of acetone and cooled to 42.5 ℃. A solution of 3.59 g of ethylenediamine and 20.81 g of the sodium salt of N-2-aminoethane-2-sulfamic acid in 107 g of distilled water was added over 5 minutes. After five minutes, 600 g of distilled water were added with high-speed stirring (650rpm), and then the acetone was distilled off under reduced pressure. A fine dispersion having a particle size of about 231 nm and a solids content of 44% by weight was obtained.

Example 7: (according to the invention)

To a reactor equipped with a heating mantle, stirrer, nitrogen inlet, reflux condenser and addition funnel were added the following: 252.96 g of a polyester diol (OH number 66, prepared from adipic acid, hexanediol and neopentyl glycol) and 44.56 g of a propylene oxide-based polyether triol (Acclaim 3300-OH number 57, number average molecular weight 3000). The stirrer was then started and the mixture was heated to 75 ℃. At this temperature 49.53 g of hexamethylene diisocyanate were added. The reaction mixture was exothermic and the temperature was raised to 80 ℃ and then maintained at 72 ℃ until an isocyanate content of 2.68% by weight (theoretical 2.29%) was reached. The mixture was diluted with 520.57 g of acetone and cooled to 44.5 ℃. A solution of 2.29 g of ethylenediamine and 15.14 g of the sodium salt of N-2-aminoethane-2-sulfamic acid in 100 g of distilled water was added over 5 minutes. After 10 minutes 557 g of distilled water were added and the acetone was distilled off under reduced pressure. A fine dispersion having a particle size of the dispersed phase of about 185 nm and a solids content of 36% by weight was obtained.

Example 8: (comparative example-No higher functional Material)

To a reactor equipped with a heating mantle, stirrer, nitrogen inlet, reflux condenser and addition funnel were added the following: 1133.0 g of a polyester diol (OH number 66, prepared from adipic acid, hexanediol and neopentyl glycol). The stirrer was then started and the mixture was heated to 70 ℃. At this temperature 201 g of hexamethylene diisocyanate were added. The reaction mixture was exothermic and the temperature was raised to 85 ℃ and then maintained at 85 ℃ until an isocyanate content of 2.84% by weight (theoretical 3.32%) was reached. The mixture was diluted with 2405 g of acetone and cooled to 47 ℃. A solution of 11.5 g of ethylenediamine and 53.3 g of the sodium salt of N-2-aminoethane-2-sulfamic acid in 300 g of distilled water was added over 30 seconds. After 15 minutes, 1800 g of distilled water were added and the acetone was distilled off under reduced pressure. A fine dispersion having a particle size of the dispersed phase of about 87 nm and a solids content of 40% by weight was obtained.

Example 9: comparative example-branching with triamine

To a reactor equipped with a heating mantle, stirrer, nitrogen inlet, reflux condenser and addition funnel were added the following: 380.0 g of polyester diol (OH number 66, from adipic acid, hexanediol and neopentyl glycol). The stirrer was then started and the mixture was heated to 70 ℃. 67.2 g of hexamethylene diisocyanate were added at this temperature. The reaction mixture was exothermic and the temperature was raised to 70-75 ℃ and then maintained at 75 ℃ until the isocyanate content reached 2.98% by weight (theoretical 3.32%). The mixture was diluted with 795 grams of acetone and cooled to 41.5 ℃. A solution of 3.49 g of ethylenediamine, 0.38 g of diethylenetriamine and 8.05 g of the sodium salt of N-2-aminoethane-2-sulfamic acid in 100 g of distilled water was added within 30 seconds. After 15 minutes, 610 g of distilled water were added and the acetone was distilled off under reduced pressure. A fine particle dispersion having a solids content of 41% by weight was obtained.

Films prepared from the dispersions of examples 6-9

A coagulant solution consists of a mixture of calcium carbonate and calcium nitrate. The coagulant solution was heated to 60 ℃ and continuously stirred. A porcelain tube was preheated to 65.6 ℃. The tube was immersed in the coagulant solution and slowly removed. The tube was rotated to evenly distribute the coagulant. The tube was dried under air for 60 seconds. The tube was then dipped into the polyurethane dispersion and slowly removed. The tube was rotated to evenly distribute the dispersion. The coating was allowed to air dry for 60 seconds. The coated tube was immersed in a vessel containing water at 48.9 ℃ for 2 minutes. The tube was placed in an oven at 148.9 ℃ for 8 minutes. After the solidified coated corn starch, the solidified film was removed from the tube by rolling the film downward. By cutting the polyurethane tube down one edge, a flat film was obtained. Each membrane was then tested for isopropanol resistance using Sterillium solution (a commercially available disinfectant/isopropanol solution).

Dumbbell-shaped samples were cut from the polyurethane films prepared as described above. The ends of the dumbbell are stretched so that the central portion of the film is elongated by 100% (i.e., a 1-inch portion is elongated by 2 inches). One drop was dropped in the middle of the stretched portion of the filmAnd (3) solution. Data were recorded for film swelling or rupture.

The films prepared from the dispersions of examples 6 and 7 did not swell, whereas the films prepared from the dispersions of examples 8 and 9 broke.

Although the invention has been described in detail in the foregoing for the purpose of illustration, it is to be understood that such detail is solely for that purpose and that variations can be made therein by those skilled in the art without departing from the spirit and scope of the invention except as it may be limited by the claims.

Claims (9)

1. A polyurethane prepolymer having an NCO content of 1 to 6 weight percent, prepared by reacting:

A) an isocyanate selected from

i) An aliphatic and/or cycloaliphatic isocyanate, and,

ii) aromatic isocyanates and mixtures of aliphatic and/or cycloaliphatic isocyanates, wherein component A) comprises (1) from 5 to 50% by weight of aliphatic and/or cycloaliphatic isocyanates and (2) from 50 to 95% by weight of aromatic diisocyanates,

B) a dihydroxy or polyhydroxy compound having a number average molecular weight of 700 to 16000, and

C) optionally dihydroxy and/or polyhydroxy compounds having a number average molecular weight of less than 700, with the proviso that,

a) at least one of the components A), B) or C) having a functionality of greater than 2, and

b) if both components A) and B) are difunctional, component C) cannot be a trihydroxy component of the formula,

R-(OH)₃

wherein R is a saturated straight or branched aliphatic group having 2 to 8 carbon atoms.

2. The prepolymer of claim 1 wherein component B) comprises at least 60 wt.% of at least one polyoxypropylene diol.

3. The prepolymer of claim 1 wherein component B) is a polyether polyol based on at least one polyoxypropylene diol, said polyether polyol having a number average molecular weight of 1000 to 8000 and an unsaturated end group content of less than or equal to 0.02 milliequivalents per gram of polyol.

4. The prepolymer of claim 1 wherein component C) is a polyether triol.

5. The prepolymer of claim 1 having an NCO content of 2 to 4 weight percent.

6. An aqueous polyurethane dispersion comprising the prepolymer of claim 1 and

D) compounds having one anionic group or group capable of forming an anionic group and two groups reactive toward isocyanate groups, and

E) a chain extender having two amine groups reactive with isocyanate groups.

7. A polyurethane film made from the prepolymer of claim 1.

8. A polyurethane film made from the prepolymer of claim 1, said film being resistant to isopropanol.

9. A polyurethane glove or condom made from the prepolymer of claim 1.