DE2145875A1 - Heat-resistant polyurethane solutions - Google Patents

Description

PATENT LAWYERS

DR.-ING. BY KREISLER DR.-ING. SCHDNWALD DR.-ING. TH. MEYER DR. FUES DI PL-CHEM. ALEK VON KREISLER DIPL.-CHEM. CAROLA KELLER DR.-ING. KLOPSCH

Dip] .- Ing. Se] ting COLOGNE 1, DEICHMANNHAUS

Cologne, September 2nd, 1971 AvK / Ax / Hz

The BF Goodrich Co. ,

500 South Main Street , Akron, Ohio 44-51 8 (USA)

"Heat-resistant polyurethane solutions "

Solid polyurethane elastomers, the products of the reaction of 1) terminal hydroxyl-containing polyesters, Hydroxy polyalkylene oxides, hydroxy polyacetals, and the like, and 2) a free glycol chain extender with 5) an organic diisocyanate are like never for example in U.S. Patents 2,871,218 and 2,899 4-11 are known, but polyurethane solutions are required in many cases. Polyurethane solutions are used for the production of foils, coatings and paints and adhesives. the Solutions of the polymers described in the above-mentioned patents can be obtained by dissolving the solid Polymers are prepared in a solvent or by solution polymerization. Lots of these polyurethane solutions must be used within a relatively short period of time after their manufacture, as they change during the storage very easily change disadvantageously. Stabilized polyurethane solutions, too, are desirable have good storage stability at relatively high temperatures.

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Heat-resistant polyurethane solutions can be obtained by adding small amounts of a stabilizing organic compound containing carboxyl groups to the polyurethane solutions. The polyurethane solutions stabilized in this way can be stored for a long time since they are protected against severe degradation even at high temperatures. The same polyurethane solution that is not stabilized is easily degraded if it is stored under the same conditions. Citric acid was added in an amount of 0.53% by weight, based on the weight of the polymer in the solution, to one of two identical polyurethane solutions, whereupon the solutions were kept ^{at 65 ° C. for 72 hours.} The polymer solution treated with citric acid still had 87% and the comparison solution only 12% of the original Brookfield viscosity. The stabilized solutions according to the invention contain (A) an elastomeric polyurethane, (B) an organic solvent and (C) an organic compound containing carboxyl groups. Organic carboxyl-substituted aliphatic, cycloaliphatic or aromatic hydrocarbon compounds, aliphatic diamine compounds or cycloaliphatic diamine compounds in an amount of about 0.01 to 3.0% by weight, based on the total weight of the polymer in the solution, serve as effective stabilizers.

The carboxyl group-containing used according to the invention Organic compounds have an excellent stabilizing ability, but no disadvantageous one Effects on the physical properties of the polyurethanes obtained from the solutions.

The polyurethane solutions according to the invention contain (A) a polyurethane, which in (B) is an organic solvent is drawn. The invention is particularly advantageous for elastomers, which by reaction 1) a terminal Polyester containing hydroxyl groups, a hydroxyl

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polyalkylene oxides, a hydroxy polyacetal and the like. and 2) a chain-extending free glycol with 3) an organic diisocyanate will.

As a reactant (1) for the preparation of the invention Polyurethanes used serve terminal hydroxyl-containing polyesters, hydroxypolyalkylene oxides, Hydroxy polyacetals and the like. These polymers have a substantially linear structure and molecular weight in the range from about 500 to 5000, preferably between 750 and 350.

The polyesters used with terminal hydroxyl groups are obtained by esterification of dicarboxylic acids, e.g. adipic acid and succinic acid or its anhydrides, with an aliphatic glycol, e.g., ethylene glycol, propanediol and 1,4-butanediol. Dicarboxylic acids are preferred of the formula HOOC-R-COOH, in which R is an alkylene radical with 2 to 8 carbon atoms. Glycols are those of the Formula HO (CHp) OH preferred, where χ has a value from 2 to 8. A ratio of more than 1 mole is preferred Glycol per mole of acid to ensure linear chains in which terminal hydroxyl groups predominate.

The hydroxypolyalkylene oxides or polyethers are essentially linear compounds containing terminal hydroxyl groups and ether bonds as the main bonds that link the carbon atoms. Examples are the polyethers, which are produced by cleaving a cyclic ether with a Lewis acid. They have the formula HO ^ CH ₂ ) _η Ρ_7 _χ Η, in which η is a number from 2 to 6 and χ is an integer.

The polyacetals are generally made by reacting an aldehyde and a polyhydric alcohol with the used in excess alcohol produced. These include, for example, the well-known products of the

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tion of aldehydes, e.g. formaldehyde, with glycols, e.g. ethylene glycol.

The molar ratio of the reactants is chosen so that the reaction product has essentially no free Contains hydroxyl groups or isocyanate groups. About 1 mole of the reactant (1) is about 0 to 15, preferably 0.1 to 10 moles of the free glycol (2) reacted, and the amount of the diisocyanate (3) is in the range from about 1.0 to 16 moles, preferably in the range from 1.1 to 11 moles, however the ratios are preferred chosen so that the number of isocyanate equivalents balances the available hydroxyl equivalents. If the production is done by solution polymerization, is usually a small amount of water is present in the polymer solution, which reacts with the isocyanate groups and leads to an unbalanced system. To prevent this from happening, the diisocyanate should be included in one slight molar excess can be used, so that the crucial molar balance is maintained will.

The chain extender free glycol, the polymeric reactant and the organic diisocyanate can, if they are in the liquid state, be mixed directly. If both or one of the respondents Are solids, they can be mixed in molten form or a solvent for that subsequent solution polymerization can be added. Any free glycols are suitable, but im general aliphatic glycols, ζ »Β, ethylene glycol and 1,4-butanediol, cycloaliphatic glycols and glycols, which contain an aryl radical, used *

Suitable as diisocyanate compounds are t the aliphatic diisocyanates, such as "Tetramethylendiisoeyaii & and hexa = _$ diisocyanate, the cycloaliphatic diisocyanates ?,,

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e.g. cyclohexyl diisocyanate, the aromatic diisocyanates, e.g. phenylene diisocyanate, the toluene diisocyanate, the dicycloaliphatic diisocyanates, e.g. dicyclohexylmethane diisocyanate, and the diary! diisocyanates, e.g. diphenylmethane-p, p'-diisocyanate, Dichlorodiphenylmethane diisocyanate, dimethyldiphenylmethane diisocyanate, diphenyldimethylmethane diisocyanate, Dibenzyl diisocyanate and diphenyl ether diisocyanate.

As solvent (B), which is used for the production of the polyurethane solutions used according to the invention, a wide variety of organic solvents are suitable, which the aforementioned urethane polymers under Ability to solve formation of gel-free solutions. The ketones, e.g. acetone and methyl ethyl ketone, are preferred, cyclic ethers, e.g. tetrahydrofuran and dioxane, substituted amides, e.g. dimethylformamide and Ν, Ν'-dimethylacetamide, Sulfoxides and sulfones, e.g. dimethyl sulfoxide and dimethyl sulfones, cyclic ketones, e.g., cyclopentanone and cyclohexanone, and combinations of the aforementioned solvents.

The reactants can be chemically bound by any known methane polymerisation process. However, solution or block polymerization are preferred. If the bulk polymerization, e.g. that in the U.S. Patents 2,871,218 and 2,899 4-11 Method, is used, the elastomer (A) is added to the solvent (B) after the polymerization. This addition of the solvent is superfluous if the preparation is carried out by solution polymerization.

Solution polymerizations can be carried out with or without a catalyst. Suitable as catalysts for this Polymerizations are the tertiary amines e.g. triethylenediamine, metal salts e.g. potassium acetate, amine salts e.g. Dimethylbenzylamine lactate, non-basic inorganic

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Metal compounds, e.g. iron (III) chloride, metal carboxylates, e.g. tin (IV) carboxylates, alkali alcoholates, e.g. sodium ethoxide, and alkali phenolates, e.g. sodium phenoxide. The solution polymerization reaction can be terminated by adding a monohydric alcohol. These polymers are very advantageous and useful as such, but additives such as Soot, silicon dioxide, lignin, dyes, antioxidants, Plasticizers and fillers, may be added.

The carboxyl group-containing organic compounds used according to the invention with excellent Stabilization ability have no adverse effects on the physical properties of the Solutions isolated polyurethanes. A comparison showed that an isolated urethane polymer, citric acid had been added had physical properties as good as a comparative polymer. Related to the weight of the total solution contains the unstabilized polymer solutions regardless of the process for their production normally about 10 to 40% by weight, preferably 15 to 35% by weight of a polyurethane elastomer (A) which is dissolved in an organic solvent (B), The degree to which a polyurethane solution is caused by the addition a small amount of the stabilizing compounds used according to the invention is protected against degradation, is by comparing the original Brookfield viscosity with the Brookfield viscosity after aging determined according to the following formula:

Brookfield viscosity after aging as a percentage of the original Brookfield viscosity =

Brookfield viscosity of the aged polymer solution _x Original Brookfield viscosity

Compared to the comparison sample, the stabilized solution showed up to 10 times higher percentage residuals

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Brookfield viscosity. The ones containing carboxyl groups stabilizing organic compound in an amount of about 0.01 to 3.0 wt .-%, preferably 0.05 to 2.0 % By weight, based on the total weight of the polymer in the solution, was added. The stabilizing used according to the invention Compounds have the structure X-Y, wherein X is a hydrogen atom, a group of the formula -COOH or a group of the formula

?1

R _D -R-

^E 3

where R is an aliphatic hydrocarbon radical with 1 to 12 carbon atoms, a cycloaliphatic hydrocarbon radical with 5 to 8 carbon atoms, an aromatic hydrocarbon radical with 6 to 14 carbon atoms, one 1 to 24 carbon atoms containing radical of an aliphatic diamine, a radical of a cycloaliphatic diamond containing 5 to 8 carbon atoms Is diamines and R ^, R ^ and R * are hydrogen atoms, Hydroxyl groups, carboxyl groups, methylene carboxyl groups, Alkyl radicals with 1 to 24 carbon atoms or aromatic hydrocarbon radicals with 6 to 14 carbon atoms. Y is a carboxyl group, a methylenecarboxyl group, or a hydrogen atom. The groups X and Y must be chosen so that the overall structure at least one carboxyl group or Contains methylene carboxyl group. When R stands for the remainder of a diamine, none of the groups R, *, Ro and R ^ are a hydrogen atom. Preferred as containing carboxyl groups stabilizing compounds are the aliphatic Monocarboxylic acids, e.g. formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, Caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid and oleic acid, the cycloaliphatic acids Monocarboxylic acids, e.g. cyclohexanecarboxylic acid and cyclooctanecarboxylic acid, the aromatic monocarboxylic acids, e.g. phenylacetic acid, benzoic acid and toluic acid, the aliphatic dicarboxylic acids, e.g. oxalic

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acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, maleic acid and fumaric acid ·, and the anhydrides of these acids, for example succinic anhydride and maleic anhydride, the cycloaliphatic dicarboxylic acids, or the cycloaliphatic dicarboxylic acids, or the anhydric anhydric acids, for example cyclohexarboxylic acids, of these cyclohexarboxylic and aromatic acids Dicarboxylic acids, for example phthalic acid, isophthalic acid and terephthalic acid, or their anhydrides, the aliphatic tricarboxylic acids, for example tricarballylic acid, the cycloaliphatic tricarboxylic acids, for example cyclohexane tricarboxylic acid, the aromatic tricarboxylic acids, for example trimesic acid, trimellitic acid, hydroxybasic acid, and hemimellitic acid , Glyceric acid, malic acid, tartaric acid and citric acid, the cycloaliphatic hydroxy acids, for example hydroxycyclohexanecarboxylic acid, the aromatic hydroxy acids, for example salicylic acid, p-hydroxybenzoic acid and mandelic acid, the aliphatic diamine carbon acids, for example ethylenediaminetetraacetic acid, N-octadecyl-Ν, Ν ¹ , N'-triacetic acid-i, ^ - propylenediamine and hexamethylenediaminetetraacetic acid, and the cycloaliphatic diamine carboxylic acids, for example 1,2-cyclohexanediamine-Ν, Ν-tetraacetic acid.

The stabilized solutions according to the invention are suitable for the production of durable, against environmental influences resistantiFilms applied to substrates can be. They can also be used to produce adhesives with high bond strength as well as excellent Wire and cable covers can be used.

example 1

In 668 g of dimethylformamide \ mrden 240 g (O _s 1174-mol) poly "· (tetramethylene adipate) glycol (molecular weight _2044? Hydroxyl value 52.5, acid number 1.2) and 3.17 g (0.0352 mole) of 1,4 ~ Butanediol dissolved. The mixture contained 0.0059. Mol water, determined by analysis according to the Karl Fischer = ·

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Method. 40.0 g of diphenylmethane-4,4'-diisocyanate (0.1585 Moles) were added. The mixture was allowed to react at 85 ° 0 for 255 minutes while under nitrogen was stirred. The reaction was terminated with 4.7 ml of n-propanol. The cement contained 30.3% total polymer solids. 0.33% by weight citric acid, based on the polymer solids, was added to one of two vessels, each containing 180 g of the cement. These solutions were kept in a heating cabinet at 65 ° C. for 72 hours. All viscosities were determined at 65.degree. The original The viscosity of the comparative sample fell from 29,600 cP to 10,400 cP, i.e. the remaining viscosity was only 35% · The stabilized cement still had 96% of its original viscosity. A small amount of citric acid is an effective stabilizer for polyurethane oil sings.

Example 2

The experiment described in Example 1 was repeated using the following polymerization approach:

Poly (tetramethylene adipate) glycol (molecular weight 950, OH number 112.9, acid number 2.6) 0.1895 mol

1,4-butanediol 0.3790 moles

Diphenylmethane-4,4'-diisocyanate 0.5779 moles

Dimethylformamide 830 g

Triethylenediamine 7.8 mg

0.083 wt .-% citric acid, based on the weight of the Polymers in cement, were a polymer solution that Containing 30.3% total solids was added. The Brookfield viscosity of the comparative sample at 65 ° C was prior to Aging 35 · 2ΟΟ cP and after aging 6000 cP, the latter 7 / ert corresponds to 18% of the original Brookfield viscosity. The one containing the citric acid After 72 hours at 65 ° C, the sample was still 85% of its original value Viscosity.

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Similar experiments to determine the change in viscosity were carried out for 277 days at room temperature. the The comparison solution was only 5.5% of its original value Viscosity, while a solution containing 0.39% by weight of citric acid based on the weight of the polymer, still had 97% of its original viscosity.

Example 3

The experiment described in Example 1 was repeated, except that 0.004-3 g of potassium acetate was used as the catalyst became. The catalyst was added to the reactor prior to the addition of the diisocyanate. The polymerization was carried out for 105 minutes. The polymerization batch had the following composition:

Poly (tetramethylene adipate) glycol

(Molecular weight 950, OH number 112.9,

Acid number 2.6) 0.1895 mol

1,4-butanediol 0.3790 moles

Diphenylmethane-4-, 4 -'-diisocyanate 0.5774 mol

Dimethylformamide 831 g

Citric acid in an amount of 0.33% by weight based on the weight of the polymer in the polymer cement was one of two polymer solutions that are 30.3% total solids contained, added. After 72 hours at 65 ° C, the sample containing citric acid still had 76% of its value original viscosity. The comparative sample had a Brookfield viscosity of 58,000 cP before aging at 65 ° C. This viscosity fell to 4-200 cP during aging, i.e. it was only 8.6% of the original Viscosity.

Example 4-

In the manner described in Example 1 were poly (tetramethylene adipate) glycol, 1,4-butanediol and diphenylmethane-4,4'-diisocyanate reacted in a molar ratio of 1.00: 2.00: 3.06 in dimethylformamide. The formed polyurethane solutions became the following carboxyl groups

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~ 11 -

containing compounds added. These solutions were aged in the following manner.

Carboxyl groups

containing

link

Amount added ****

Viscosity after aging as a percentage of the original viscosity

with
additive

Comparison sample

Tartaric acid
Tricarballylic acid
Trimic acid

N-octadecyl-N,! * ', N ¹ -triacetic acid-1,3-propylenediamine

Ethylenediaminetraacetic acid

acetic acid

Succinic acid

Succinic anhydride

0.33 0.33 0.33

0.33

77 *
69 *
48 *

66 *

11 * 11 * 11 *

8.6 *

0.67 54 * 15 * 0.42 74 *** 15.5 *** 0.39 67 ** 18 ** 0.39 51 ** 18 **

* 72 hours at 65 ° C ♦♦ 156 days at 23 ° C *** 68 days at 22 ⁰ C.

*** ♦ in% by weight, based on the total weight of the polymer in cement.

Example 5

Solution polymerization was carried out in the manner described in Example 1 performed with the following approach:

Poly (tetramethylene ether) glycol (molecular weight I510, OH number 74, Acid number 0.01)

0.1586 mole 0.6344 mole 0.8011 mole 1150 6

1,4-butanediol

Diphenylmethane-4,4-diisocyanate Dimethylformamide

Citric acid in an amount of 0.33% by weight, based on the weight of the polymer in the solution, became one of two 180 g samples of the 30.3% total solids

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Polyether urethane cement added. The Brookfield Viscosity of the comparison sample was 21,400 cP before aging and 5400 cP after 72 hours of aging at 65 ° C, i.e. its viscosity after aging was only 34% of the original 7 / ertes, while that of citric acid containing solution still had its original viscosity after aging.

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Claims (1)

- 09 -. Claims 1. Heat-resistant polyurethane solutions containing (A) a polyurethane elastomer, (B) a solvent for the polyurethane and (0) a small amount of a carboxyl group-containing aliphatic, cycloaliphatic or aromatic hydrocarbon compound or aliphatic or cycloaliphatic diamine compound. 2. Polyurethane solutions according to claim 1, characterized in that they are essentially a polyurethane (A) linear thermoplastic polyurethane and a carboxyl group-containing compound (C) of the Formula X-Y where X is a hydrogen atom, a carboxyl group or a compound of the formula ?1 R ₀ -R- ^H 3 is where R is an aliphatic hydrocarbon radical with 1 to 12 carbon atoms, a cycloaliphatic hydrocarbon radical with 5 to 8 carbon atoms, an aromatic one Hydrocarbon radical with 6 to 14 carbon atoms, a radical containing 1 to 24 carbon atoms of an aliphatic Diamines ■ or one containing 5 to 8 carbon atoms Radical of a cycloaliphatic diamine and R / p Rg and R ^ for hydrogen atoms, hydroxyl groups, Carboxyl groups, methylene carboxyl groups, alkyl radicals with 1 to 24 carbon atoms or aromatic hydrocarbon radicals with 6 to 14 carbon atoms and Y is a Is carboxyl group, a methylenecarboxyl group or a hydrogen atom and the groups X and Y are selected are that the overall structure has at least one carboxyl group or methylenecarboxyl group, where none of the radicals R, «, Ro and R, is a hydrogen atom, when R is a residue of a diamine. 209813/1812 2U5875 5. Polyurethane solutions according to claim 1 and 2, characterized in that that it is an essentially linear thermoplastic, elastomeric polyurethane (A) Polyurethane containing the product of the reaction of (1) a terminal hydroxyl group Polyester, hydroxypolyalkylene oxide or hydroxypolyacetals and (2) one serving as a chain extender is free glycols with (3) an organic diisocyanate. 4. Polyurethane solutions according to claim 1 to 3 »thereby characterized in that the carboxyl group-containing compound (C) in an amount of 0.01 to 3.0 wt .-%, based on the weight of the polyurethane (A). 5. Polyurethane solutions according to claim 1 to 4, characterized characterized in that it contains a carboxyl group-containing compound (C) of the formula X-Y in which X is a compound the formula 9i R ₀ -R- is in which R is an aliphatic hydrocarbon radical with 1 to 8 carbon atoms, a radical of an aliphatic diamine containing 1 to 12 carbon atoms, one 6 carbon atoms containing radical of a cycloaliphatic diamine and Rj, Rp and R ^ for carboxyl groups, Methylenecarboxyl groups and alkyl radicals with 1 to 18 carbon atoms are present, Y is a carboxyl group, methylenecarboxyl group or is a hydrogen atom and the groups X and Y are selected so that the overall structure contains at least one carboxyl group or methylenecarboxyl group, and that it is used as solvent (B) Contain dimethylformamide or dimethylacetamide. 209813/1812 Polyurethane solutions according to claims 1 to 5 »thereby characterized in that, as polyurethane (A), it is the product of the reaction of (1) about 1 mole of a terminal Hydroxyl group-containing compound, (2) about 0.1 to 10 moles of a free chain extender Glycols; and (3) about 1.1 to 11 moles of an organic diisocyanate and the carboxyl group-containing compound (0) in an amount of 0.05 to 2.0% by weight, based on the weight of the polyurethane (A). 209813/1812