DE2123962B2 - Process for the production of microporous fabrics - Google Patents

Description

2. The method according to claim 1, characterized in that that a solvent is used in which the finished polymeric addition product is insoluble, is.

It is known to produce microporous sheet-like structures by a reactive process in which one Polyurethanes synthesized directly microporous. Ui.ter fabrics are used in this context Foils, textiles laminated with foils, such as fleeces, fabrics, etc., split leather or leather, bonded fleeces and Understood non-woven synthetic leather. Here, a method has proven to be particularly advantageous in which one in a two-stage process from an NCO prepolymer and a suitable chain extender directly synthesized a microporous polyaddition product. The prepolymer can be used in a known manner Can be obtained from excess polyisocyanate and low molecular weight polyhydroxy compounds. The second reaction step, the polyaddition with chain extenders, can be carried out in a suitable Reaction medium are made, which the Alisgangsverbindungen the Polyadditionsreaktioii to able to solve, in which the finished polyaddition product is insoluble. During or after the polyaddition the reaction medium can be removed. This procedure results in directly microporous ones Polyaddition products. The procedure is known and z. B. in the German Offenlegungsschrift 16 94081, 1694213 and the Belgian patents 7 15 003.7 19 174.7 19 272 published.

It has been shown that the technical implementation of this two-stage reaction causes difficulties can. When operated in batches, the prepolymer changes its viscosity and loses it - due to the inevitably longer stay at a higher temperature - isocyanate groups. This is an even Polyaddition reaction associated with difficulties over a long period of time. Also is an exact dosage of the prepolymer is problematic because of its high and fluctuating viscosity.

The invention relates to a process for the production of sheet-like structures from polyurethanes after a multi-stage process, whereby one

1. a higher molecular weight compound containing at least 2 OH groups and a polyisocyanate in amounts corresponding to an equivalent ratio of NCO groups to OH groups of 1.3-7 to 1, if necessary in the presence of a solvent, intensely mixed,

2. the prepolymer formed with free NCO groups with at least two Zerewitinoff-active Low molecular weight compound containing Η atoms, if necessary in a solvent, mixes intensively, wherein the molar ratio of NCO: active H = 035 to 2 to 1, the mixture to one Sheetlike structure is deformed and the polyaddition, optionally with heating and under Removal of any solvent used, completed, which is characterized by that the polyaddition and deformation are carried out continuously, with one in the 1st stage the polyaddition between the NCO and the OH groups continues until the content of free NCO groups of the prepolymer formed in the range between 25% and 60% is below the value corresponding to complete polyurethane formation.

The starting materials for the process according to the invention are higher molecular weight at least 2 terminal OH groups containing compounds, such as polyethers, polyesters, polycarbonates, polyacetates, polythioethers, Polysiloxanes. Such products are described e.g. B. in J. H. Saunders and K. C. Frisch, "Polyurethanes" I, New York (1962), pages 32 to 61 and in the literature cited there.

Particular mention may be polyester of adipic acid and optionally mixtures forward Dialkoholen.z. B.

Ethylene glycol.

Propylene glycol,

Butanediol (1,4),

Hexanediol (2.5),

2,2-dimethyl-propanediol- (1,3).

Hexanediol- (l, 6),

2-methylhexanediol- (l, 6),

2,2-dimethylhexanediol- (1,3),

p-bis-hydroxylmethyl-cyclohexane,

3-methylpentanediol- (1,4),

2,2-diethyl-propanediol- (1,3),

preferably those with diols or mixtures of diols with five or more carbon atoms, as such Polyester has a relatively good resistance to hydrolysis and especially when diols with pendant positions are also used Alkyl radicals also have good low temperature elasticity in the end products. Polyester, which by polymerization of caprolactone on diethylene glycol with a narrow molecular weight distribution are also well suited starting materials. Especially mentioned here

the polyesters made from diphenyl carbonate and glycols can be obtained.

Excellent hydrolysis-resistant polyurethanes or polyurethane ureas can be made from polyalkylene ethers, obtained such as polypropylene glycols, particularly preferably from polytetramethylene ether diols, which optionally can also be present as mixed polyethers.

Surprisingly, the inventive method even when using water-miscible polyhydroxy compounds, e.g. B. polyethylene glycol ether diols, feasible, with polyurethanes being obtained with a high water absorption. As a low molecular weight Examples of chain extenders containing at least 2 OH or NH groups are Called polyols, aminols and polyamines

Chain extenders are said to have a molecular weight from 18 to about 500, preferably from 32 to 350. In addition to water, for example, possibly in a mixture,

Ethylene glycol, propylene glycol. Butanediol (1,4),

Hexandio! - (1,6),

Hydroquinone bis - (/? - hydroxyäthyläthe;},

p-xylylene glycol, also ethylenediamine,

1,2- or 1,3-propylenediamine,

1,4-tetramethylenediamine,

1,6-hexamethylenediamine,

2,2,4-trimethylhexanediamine- (1,6),

I -Methyl-cyclohexane-2,4-diamiπ,

l-amino-3-aminomethyl-3 _I 5,5-trimethyl-

cyclohexane, 4,4'-diaminodicyclohexylmethane,

Bis (aminopropyl) piperazine or aromatic

diprimary amines such as

4,4'-diamino-diphenylmethane,

Bis-2,2- (4-aminophenyl-) propane,

4,4'-diamino-diphenyl sulfide.

4,4'-diamino-diphenyl ether,

1-methyl-2,4-diaminobenzene or araliphatic

diprimary diamines such as

m-xylylenediamine,

Λ, Λ, Λ ', χ'-tetramethyl-p-xylylenediamine,

1,3-bis- (j3-amino-isopropyl) -benzene, also

sulphonic acid group-containing diamines, wi «;

4,4'-diamino-stilbene-2,2'-disulfonic acid or

4,4'-diaminodiphenylethane-2,2'-disulfonic acid,

Ethylenediamine-N-butylsulfonic acid,

Hexamethylenediamine-1,6-N-butylsulfonic acid,

1,6-diaminohexamethylene-3-sulfonic acid or its

Alkali salts, hydrazides, such as

Carbodihydrazide, oxalic acid dihydrazide.

Malonic acid dihydrazide, succinic acid dihydrazide,

as well as addition products of ethylene oxide and

Propylene oxide, ammonia or aliphatic

or aromatic amines, such as

Di-, tri-ethanolamine or methyl or

Phenyldiethanolamine, which makes it dyeable

the process products is increased, furthermore

Hydrazine, e.g. B. also in the form of

Hydrazine hydrate, methylhydrazine, as well

Dihydrazines, such as

Ν, Ν'-diamino-piperazine.

Secondary diamines, preferably with a symmetrical structure, such as piperazine or 2,5-dimethylpiperazine can also be used or 3,3'-dichloro- or 3,3'-dimethyl-4,4'-li- (methylaminophenyl) methane be used.

The conventional polyisocyanates are used for the process (described e.g. by W. Siefken, Liebigs Ann.: hem. 562, 75-136 [1949] or higher molecular weight,

Reaction products containing at least two NCO groups per molecule (so-called prepolymers with a WCO: OH ratio S 1.2) from the above Compounds containing OH groups and excess polyisocyanates are suitable. As polyisocyanates come in particular aliphatic, araliphatic, aromatic and heterocyclic diisocyanates or their mixtures in question. Particular mention should be made of diisocyanates with a symmetrical structure, e.g. B.

Diphenyimethane-4,4'-diisocyanate,
Diphenyldimethylmethane ~ 4,4'-diisocyanate,
2,2 ', 6,6'-tetramethyl-diphenylmethane-4,4'-diisocyanate, diphenyl-4,4'-diisocyanate,
Diphenyl ether 4,4'-diisocyanate or its alkyl,
Alkoxyl- or halogen-substituted derivatives,
Furthermore, toluene-2,4- or 2,6-diisocyanate, or their technical mixtures,
2,4-diisopropylenephenylene-l _r 3-diisocyanate,
m-xylylene diisocyanate, p-xylylene diisocyanate and
Λ, Λ, α ', α'-Tetramethyl-p-xylyJi vdiisoeyanat,

furthermore alkyl or halogen substitution products of the above diisocyanates, ζ. Β.

2,5-dichloro-p-xylylene diisocyanate or
Vetrachloro-p-phenylene diisocyanate,
dimeric ethylene-2,4-diisocyanate,
Bis (3-methyl-4-isocyanatophenyl) urea
or US naphthalene diisocyanate.
Aliphatic diisocyanates such as
Hexane-1,6-diisocyanate,
Cyclohexane-l / t-diisocyanate,
Dicyclohexylmethane ^^ '- diisocyanate,
1-isocyanato-3-isocyanatomethyl-3,5,5-trimethylcyclohexane or
2,2,4-trimethylhexane-1,6-diisocyanate

can optionally be used partially and result in very little discoloration after exposure Products. Also diisocyanates such as w, o / -di (isocyanatoethyl) benzene or 1,2,3,4,5,6-hexahydro-diphenylmethane-4,4'-diisocyanate give little under exposure discolouring products.

Because of its technical accessibility rnd from the Properties are preferably diphenymethane-4,4'-diisocyanate, the isomeric tolylene diisocyanates and, if appropriate, some of the hexane-1,6-diisoeyanate and dicyclohexylmethane-4,4'-diisocyanate are used.

Preferred chain extenders are diprimary diamines from the series of aliphatic and aromatic diamines and hydrazine derivatives. Preferred compounds that may be mentioned are

Hydrazine,

Methylhydrazine.

4,4'-diaminodiphenylmethane.

4,4'-Dianiinodipheny lather,

2,4'-Toluene diamine.

Piperazine,

2, ^r ) dimethylpiperazine and

Hexamethylenediamine.

The reaction to the prepolymers with the diisocyanates is at low molecular weights Polyhydroxy compound, e.g. 750 to 1250 preferably with low NCO / OH ratios, e.g. B. 2.0: I to 1.25: 1, made at high molecular weight,

ζ. B. 1700 to 2500, preferably with high NCO / OH ratios, z. B. 3: 1 to 1.65: 1.

In addition to the higher molecular weight polyhydroxy compounds, low molecular weight diols (molecular weight preferably under (250)), e.g. B. ethylene glycol, butanediol (1,4), bis-N.N- (0-hydroxylethyl) methylamine, Bis-N, N- (j? -Hydroxypropyl) -methylamine, N, N'-bishydroxyethyl-piperazine or hydroquinone bis (jJ-hydroethyl ether) in amounts, for example from 10 to 300 Mol percent of the OH content, preferably 20 to 100 mol percent of the higher molecular weight polyhydroxy compound, can also be used. The use of diols with tertiary nitrogen specifically increases the Can be dyed, improves lightfastness and provides the point of attack for further post-treatment, ζ. B. Crosslinking with, for example, strongly alkylating compounds, such as 4,4'-dichloromethyldiphe-

nvläthpr

- ■ j -

The content of NCO groups in the pre-adducts is important for the properties of the products obtained therefrom Polyurethanes. It should be at least 0.50 percent by weight and should preferably be between about 1.00 and about 7.6 percent by weight, especially between about 1.3 and 4.0 percent by weight, so that the polyurethanes have sufficiently high melting points, tensile strength, elongation at break and stress values. in the In the case of the chain extension reaction with water, the NCO content is preferably higher, e.g. B. between 3.5 and 7.6 percent by weight, since some of the NCO groups are first saponified to form amino groups.

The solvents used for the process according to the invention are those boiling below 250 ° C. under the reaction conditions liquid organic compounds suitable which, under the reaction conditions, do not interfere with the products React.Suitable solvents are e.g. B. aliphatic hydrocarbons such as pentanes, hexanes and homologues of optionally alkylated cycloalkanes, such as cyclohexane, methylcyclohexane, cyclododecane.

Petroleum fractions, especially mixtures of aliphatic hydrocarbons with boiling points between 80 and 250 ⁼ C, e.g. ligroin, mineral spirits, white spirit, hydrocarbon mixtures with 12-18 carbon atoms, turpentine oils, mixed aliphatic-aromatic hydrocarbons such as tetralin, decalin, aromatic hydrocarbons such as benzene, Toluene, xylene, ethylene benzene. Diethylbenzene, mesytylene, chlorinated hydrocarbons, such as di-. Tri-, carbon tetrachloride, di-, tri-, perchlorethylene. Di-, tri-. Tetra-, penta-, hexachloroethane, 1,2- and 1,3-dichloropropane, i-butyl chloride, dichlorohexane. Chlorocyclohexane, chlorobenzene. Chlorotoluene, ethers, such as di-n-propyl, di-i-propyl ether, di-n-butyl ether, ethyl propyl ether, anisole, phenetole, esters, such as carbonate diethyl ester, dimethyl ester, ethyl acetate, propyl ester, butyl ester, amyl ester, -hexyl ester, methoxybutyl acetate, methyl propionate, ethyl ester, methyl glycol acetate, dimethyl oxalate, ketones such as acetone, methyl ethyl ketone, methyl ibutyl ketone, methoxyhexanone, mesityl oxide, phoron, cyclohexanone.

The reaction of the starting compounds can be carried out with the known isocyanate polyaddition catalysts be catalyzed (see J. H. Saunders and K. C Frisch, "Polyurethanes" I, New York [1962], page 212). Volatile tertiary amines are preferably used, since these are known to have the least adverse effect on the hydrolysis resistance of the end products. Preferably However, the reaction is carried out without catalysts, since the reaction rate of the poly

addition of NCO groups with NH2 groups is sufficiently rapid.

The method is preferably carried out as follows (see FIG. 1). A solution of the higher molecular weight compound containing at least 2 hydroxyl groups is prepared in a reaction vessel A, e.g. B. the polyester, in a second vessel B the solution of the polyisocyanate and in the third reaction vessel C the solution of the chain extender. As described in the figure, the hot solutions of the higher molecular weight two OH group-containing compounds and the polyisocyanate are now fed into a mixing vessel M ₁ with a small volume (approx. 1 ... 1000 cm ¹ ) via a metering pump P \, Pi pumped at a high stirring speed (approx. 1000 ... 10 000 rpm), combined here and conveyed further into a reaction vessel G. The reaction vessel has such dimensions that the

remains until it emerges from the same and enters a second mixing vessel Mi. The solution of the chain extender is also conveyed directly into the second mixing vessel M2 via a metering pump P ₁ , where it is combined with the solution of the prepolymer while stirring vigorously, whereupon a reaction mixture is formed which can be applied to substrates after being discharged from the mixing vessel. After application to the base, ie after the reaction mixture has been shaped, the polyaddition is completed with simultaneous removal of the solvent. If homogeneous, non-porous planar structures are to be produced, the solvent is expediently left out. In this case, the reactants must be liquid at the processing temperature.

The reaction vessel for prepolymer production must have such a volume that at a given Delivery rate for the polyisocyanate and the higher molecular weight polyhydroxy compound that forms Prepolymers remain in the vessel for a sufficiently long time. The time that the prepolymer in the reaction vessel must stay. is given by the reactivity of the isocyanate, the concentration of the prepolymer in the Solvent, the polarity of the solvent and the temperature of the solution. The NCO content of the resulting After leaving the reaction vessel, prepolymers should not exceed the theoretical level by a maximum of 25% calculable and a maximum of 60% below the theoretically calculable. The NCO content is preferably 15% above and 30% below the theoretical value. If the NCO content is higher than calculated, it is this is a sign that not all OH groups of the higher molecular weight dihydroxy compounds with polyisocyanate are exhausted. In the continuous further processing of such a prepolymer can no polyurethane with good properties is produced.

In order to demonstrate the influence of the reaction temperature and the solvent on the isocyanate-hydroxyl reaction, some data are mentioned as z. B. Saunders-Frisch "Polyurethanes", Chemistry and Technology, Part 1, New York, 1962, are summarized, mentioned the reaction of phenyl isocyanate with 1-butanol in xylene runs at 35 ° C (compared with the same reaction at 0 ⁰ C ) approx. 5 times faster than at 0 ° C (page 145). Similarly, the reaction rate changes depending on the polarity of the solvent. On page 146 (loc. Cit) it is described that the reaction of phenyl isocyanate with alcohol at 20 ° C in toluene proceeds 40 times faster than in dioxane. It is also of crucial importance whether the

Hydroxyl group on the higher molecular weight compound is primary or secondary. Primary hydroxyl groups react around 3 times faster than secondary hydroxyl groups if the other reaction parameters do not be changed (see. Page 145, loc. cit.). It goes without saying that the Isr> "yanate hydroxyl reaction the type of isocyanate essential. Aliphatic isocyanates react approximately 40 times more slowly than aromatic isocyanates.

The dilution of the reactants in solvents and the delivery speed of the pumps are other important parameters which have an influence on the residence time of the prepolymer in the reaction vessel to have. Since one can also add highly polar, higher solvent solvents at the same time, such as ι ϊ

Ν, Ν-dimethyl-, Ν, Ν-diethylformamide,
Ν, Ν-dimethylacetamide, N-methyl-morpholine.

N-acetylpyrrolidine, butyrolactone,
Ν, Ν'-diacetylpiperazine, dimethyl sulfone, ^2ft

Dipropyl sulfone, ethylene carbonate, methyl benzoate, propiolactone, N-methylpyrrolidone,
Hexamethylphosphoric acid amide,
Tetramethylurea, dimethyl sulfoxide,
Dimethylcyanamide, camphor and their ² '

Mixtures,

but dimethylformamide and dimethylacetamide are preferred, these solvents - provided they are present during prepolymer production jo - The reaction time of prepolymer formation can be lengthened, which translates into larger dimensions of the residence time vessel makes noticeable. However, preference is given to adding such solvents to the chain extender and thus controls the reaction time of the r, end extension. As a general benchmark for the The following applies to the residence time in the reaction vessel: Residence time in the reaction vessel 5 ... 500 min_ preferably 15 ... 150 min. In addition, the dwell time spectrum must be as narrow as possible, which is particularly good in a jo slender vessel can be realized (slenderness height / diameter 2 ... 20). This should be in this Reaction vessel a stirrer can be installed, which preferably has a radial flow without an axial flow Mixing causes.

The method according to the invention can be used for coating substrates. Example of this is the coating of textiles, leather, wood, fleece, concrete, etc. in a direct or reverse process. Farther substrates can be treated with the products that can be manufactured according to the process. Examples are the Binding of fleeces, the consolidation of small particles, ζ. B. sawdust, wood splinters, etc. Of course the processes can also be coupled. For example, substrates can be impregnated and conceal.

The process allows other polymers, dyes, fillers, stabilizers, crosslinking agents etc. to be used in the form of solutions, organic dispersions or as solids, the advantageous eo be incorporated into the starting solution at times.

One advantage of the process is the general scope of application with regard to the Starting components and the solvent The products prepared according to the process can be used as Find filter materials and as porous coatings for textiles, etc. use.

Example I.

A: 2 kg of a polypropylene glycol ether (OH number 56) (2 mol OH) and 2 g di-aza-bicyclo-octane are in heated to 100 ° C in a 2-liter three-necked flask.

B: In a 2. 2-liter three-necked flask, 1 kg becomes one Mixture of 65% 2,4- and 35% 2,6-tylenediocyanate also heated to 100 ° C.

C: 500 g of a liquid mixture of 70% 2,4- and 30% 2,6-diamino-3,5-diethyltoluene are in brought to 100 ° C in a 1 L three-necked flask.

The delivery rate of the individual pumps was determined depending on the piston stroke:

Piston stroke lot B. C. A. (mm) (g / min) 3.3! rn 5.6 6.62 o! s - - 13.2 0.9 - 11.2 - 1.1 - 22.4 - 2.3 - - - 3.5 26.7 - - 6.4 53.4 _ - 9 76.9

With the setting A 3.5 mm (= 26.7 g / min.) And B 0.5 mm (= 5.6 g / min.), The reactants A + C were a mixing head in a 108 ⁰ C warm steam heated residence vessel of 700 ml. After the prepolymer had emerged from the residence vessel, it was conveyed into a mixing head, mixed with the amine (C: 0.3 mm = 33 g / min.) And applied to a steel belt. The resulting film had a tensile strength of 40 kgf / cm ² and an elongation at break of 150%.

Leather or a Velveton was placed on part of the polyurethane and peeled off after 15 minutes. It Well kink and solvent-resistant coated leather or textiles were obtained.

A fleece was directly impregnated with part of the reaction solution and a leather was coated. These too 2 attempts were satisfactory.

Example 2

The following amounts were added to 3 10-liter three-necked flasks weighed in:

A: 1.65 kg 4,4'-diisocyanatodiphenylmethane and

6.81 kg of chlorobenzene

B: 6.75 kg in vacuo dehydrated (<0.01% H ₂ O) polyethylene adipate (OH number 56) and

1.71 kg chlorobenzene
C: 0.43 kg of dimethylformamide

632 kg of xylene

0.284 kg of 4,4'-diaminodiphenyl methane

All 3 solutions were heated to 100 ° C. with stirring. The flow rate of the was then tested individual pumps with different piston strokes. The following values were found:

(mm stroke) (g) A. (g) B. (g) C. 12th 104.6 113.4 153.5 9 663 82.4 110 6th 52.7 553 693 3 24.4 26.8 34.6

In a diagram in which (mm) stroke was plotted against (g) product A, B or C on the ordinate on the abscissa, straight lines were obtained by connecting the points. Then component A (corresponding to 40 g of product) was started with a stroke of 4.8 mm and component B with a stroke of 4.4 mm a KPG stirrer was provided to promote and to promote in a 96 ⁰ C hot dwell vessel with jacket heating and stirrer . After 70 minutes the prepolymer emerged from the residence vessel; it had an NCO content of 1.71% (calculated 1.64% NCO) and emerged from the vessel in an amount of 79 g / min. At this point in time, the third component C was conveyed with a stroke of 6.2 mm (corresponding to 75 g / min.) Together with the prepolymer into a second mixing head, which was manufactured analogously to the first mixing head. The mixed product

10

was conveyed on a SO-60 ° C hot glass plate and dried. After the end of the polyaddition and evaporation of the solvent, a microporous film was created with the following physical properties exhibited:

Flexometer: Tensile strenght:

Elongation at break:

Tear strength:

> 200,000 kinks in the Bally flexometer without damage 88 kp / cm *
560%

12.6 kp / cm with a water vapor permeability of
11 mg / h cm ²

Tests carried out analogously on steel plates, Teflonized glass fiber fabric and release paper showed similarly good results.

For this purpose I sheet drawings

Claims (2)

K) I) Claims: 1. A process for the production of sheet-like structures from polyurethanes, wherein one 1. a high molecular weight compound containing at least two hydroxyl groups and a Polyisocyanate in an NCO / OH equivalent ratio of 13: 1 to 7: 1, optionally in Presence of a solvent, intensely mixed, 2. the prepolymer obtained in this way continuously with at least two Zerewitinoff-active Low molecular weight compound containing hydrogen atoms in an equivalent ratio from NCO groups to active hydrogen atoms from 035: 1 to 2: 1, optionally in a solvent, mixed intensively, this mixture is shaped into a flat structure uru. ' the polyaddition, if necessary under '" Enormous as well as removing the possibly used solvent, completed, characterized in that that the polyaddition and deformation are carried out continuously, with one in the 1st - "' Stage the polyaddition reaction between the NCO and the OH groups take place for as long leaves, until a prepolymer is formed, the content of free NCO groups in the range is between 25% above and 60% below the "'theoretical value.