NO143926B - DEVELOPMENT DEVELOPMENT. - Google Patents

Description

Process for the production of polyurethane polymers.

The present invention relates to a method for the production of new polyurethane polymers with improved dyeability.

The elastomeric polymers that are formed

by chain extension of the reaction product of a polyalkylene ether glycol and an organic diisocyanate with hydrazine is an example of a class of polyurethane polymers which are known to be very useful in the production of shaped objects or articles such as micro-porous coatings, non-porous films and textile fibers However, since these extended chain elastomeric polyurethanes do not readily dye or have any special ability to retain dyes when preferred light-true acid dyes are used, there is a limit to their applicability to colored products .

For example, it can be mentioned that vapor-permeable plate materials have been produced with properties and durability corresponding to the most commonly used types of shoe upper leather by covering a suitable tek steel product with a microporous coating of the above-mentioned elastomeric polyurethane which is chain-lengthened with hydrazine . Until the present invention, however, there has been no completely satisfactory method for the production of polyurethane polymers for e.g. microporous coatings in a color with good richness, uniformity, wash fastness and light fastness. When said coating is dyed in an acidic dye bath containing e.g. a chrome-plated monoazo dye, the color may initially be good and rich, but often has a tendency to eventually become mottled. In addition, most of the color is removed during the washing operation that normally follows. If the washing operation is omitted, the color fades to a significant extent when the coating is subjected to washing with clean water or soapy water and when it is exposed to sunshine.

A somewhat improved resistance to fading when the colored coating is exposed to water or light is achieved by mixing different additives into the chain-extended elastomer, for example polymeric aliphatic amines. But even the best of these additives are affected by one or more of the following disadvantages: a) The end product has inferior physical properties. b) Difficulties arise when applying preferred methods to

production of film and microporous material.

c) The color cannot withstand washing to the desired extent, because the additive is not inert

facing water.

d) The additive is too expensive for practical use in competitive products.

According to the present invention, however, there is now a method for producing essentially linear polyurethane polymers with improved dyeability, with a molecular weight in the range 5,000-300,000, and which are soluble in organic solvents, especially in dimethylformamide, whereby organic diisocyanates are reacted with polyalkylene ether glycols or with polyesters with hydroxyl end groups, and the resulting reaction product which has isocyanate end groups, is chain extended using chain extenders with free amino groups, using a mixture of two compounds for the chain extension, namely: a) a compound in which two reactive hydrogen atoms are bonded to amino nitrogen atoms, preferably hydrazine, and

b) an amine of the formula:

in which R denotes an alkyl group with

from 1 to 4 carbon atoms, the two compounds a) and b) being used in a molar ratio of 95:5 to 50:50, preferably in a molar ratio of 95:5 to 70:30.

The new polyurethane polymers can be produced by mixing a molar excess of an organic diisocyanate with a polymeric material containing active hydrogen, in the form of a polyalkylene ether glycol or a polyester with hydroxyl end groups and heating the mixture to a temperature in the range of 50° -120° C until a polyurethane prepolymer is formed with OCN — end groups (isocyanate).

Alternatively, the diisocyanate can be reacted with a molar excess of the polymeric material containing active hydrogen, after which the prepolymer is formed by adding further diisocyanate.

Aromatic, aliphatic and cycloaliphatic diisocyanates or mixtures thereof can be used in the production of the prepolymer. Such diisocyanates are, for example, tolylene-2,4-diisocyanate, tolylene-2,6-diisocyanate, m-phenylene-diisocyanate, biphenylene-4,4'-diisocyanate, methylene-bis-(4-phenyl-isocyanate), 4-chloro-1,3-phenylene diisocyanate, naphthalene-1,5-diisocyanate, tetramethylene-1,4-diisocyanate, hexamethylene-1,6-diisocyanate, decamethylene-1,10-diisocyanate, cyclohexylene-1, 4-diisocyanate, methylene bis(4-cyclohexyl isocyanate) and tetrahydronaphthalene diisocyanate. Arylene diisocyanates, i.e. isocyanates where the isocyanate groups are bound to an aromatic ring, are preferred. In general, they react more easily than the alkylene diisocyanates.

The preferred active-hydrogen-containing polymeric material used in the preparation of the prepolymer is a polyalkylene ether glycol. The most useful polyglycols are those which have a molecular weight of from 300 to 5000, preferably from 400 to 2000 and include, for example, polyethylene ether glycol, polypropylene ether glycol, polytetramethylene ether glycol, polyhexamethylene ether glycol, polyoctame ethylene ether glycol, polynonamethylene ether glycol, polydecamethylene ether glycol, polydodecamethylene ether glycol and mixtures thereof. Polyglycols containing several different radicals in the molecular chain, such as for example the compound HO(CH2H40)nH where n is an integer greater than 1, can also be used.

Polyesters that can be used instead of or together with the polyalkylene ether glycols are, for example, those formed by the reaction of acids, esters or acid halides with glycols. Suitable glycols are polymethylene glycols such as ethylene, propylene, tetramethylene and decamethylene glycol, substituted polymethylene glycols such as 2,2-dimethyl-1,3-propanediol, cyclic glycols such as cyclohexanediol, and aromatic glycols such as xylylene glycol. Aliphatic glycols are generally preferred when maximum product flexibility is desired and when producing micro-porous articles. These glycols are reacted with aliphatic, cyclo-aliphatic or aromatic dicarboxylic acids, lower alkyl esters or ester-forming derivatives thereof to form relatively low molecular weight polymers which preferably have a melting point lower than approx. 70° C, and molecular weights corresponding to those indicated for polyalkylene ether glycols. Acids for the production of such polyesters can be, for example, succinic acid, adipic acid, sebacic acid, terephthalic acid and hexahydroterephthalic acid as well as alkyl- and halogen-substituted derivatives of these acids.

The polyurethane prepolymer with isocyanate end groups is reacted with a chain extender consisting of a compound of the formula

where R is an alkyl group containing from 1 to 4 carbon atoms (ie a methyl, ethyl, propyl or butyl group). In the preferred compound, R under the central N atom is methyl and the other two R groups propyl. The preferred compound is thus N-methyl-amino-bis-propylamine.

The chain extender is used in an amount of 5-30 mole percent, together with 95-70 mole percent, of another compound with two active hydrogen atoms bound to amino nitrogen atoms, preferably hydrazine. Other chain-extending compounds that can be used together with the main compound are, for example, monosubstituted hydrazines, dimethyl-piperazine, 4-methyl-m-phenylenediamine, 4,4'-diamino-diphenyl-methane, 1,4-diamino-piperazine , ethylenediamine and mixtures thereof.

The new polyurethane polymers prepared using a chain extender containing more than approx. 5 mole percent of the main compound generally shows improvements in dye retention ability. Addition of more than approx. 20-30 mole percent of the main chain extender gives relatively little further improvement in color depth and dye retention and is generally not preferable for economic reasons. The best results are achieved in most applications with approx. 10-30 mole percent of the main chain extender; this is particularly the case when the polymer is to be used for the production of 1 micro-porous plate materials by methods involving treatment of a solution of the polymer with an inert liquid.

During the chain extension reaction, the pre-polymeric molecules are linked together to form an essentially linear polyurethane polymer. The molecular weight of this is usually at least 5,000 and occasionally as high as 300,000. As the polymer has rubbery elasticity and extensibility, it is referred to as an elastomer, although these properties can vary greatly from product to product depending on the chemical structure and the materials it is connected with.

Shaped objects can be produced by known methods from the polymer or from mixtures thereof with other polymers and various additives. The polymer can, for example, be formed into textile fibers by the known methods for producing spandex fibers. It can also be used for the production of non-porous films or sheets using known methods such as pressing, calendering or solution casting. It can also be used for the production of shaped objects by pressing or shaping in a suitable form, as well as for artificial leather, macroporous or microporous coatings, films, plates or shaped articles using methods whereby porosity is produced in such articles.

The new polymers and articles containing the same can advantageously be dyed by immersion in or by contact with a dye bath containing an acidic dye. The dye may be any acidic dye, for example of the type used when dyeing wool or nylon in a neutral to slightly acidic aqueous dye bath (for example at a pH in the range 4.0 to 6.8), or it may be an acid dye of the type used for dyeing cotton. Metallized monoazo dyes, such as chromed monoazo dyes, are particularly useful. The best results are generally obtained with a half-chromed monoazo dye, which means that they contain a chromium atom bound to 2 molecules of the azo compound. Good results are also achieved with a fully chromed monoazo dye.

Further improvement in the ability of the colored objects to retain their color when exposed to sunlight for extended periods of time can be achieved by the addition of one or more suitable additives, such as certain polymeric aliphatic amines and certain pigments (for example carbon black or titanium dioxide) for filtering ultraviolet radiation (eg substituted benzophenones), and antioxidants (eg certain substituted phenolic compounds).

The new polyurethane polymers according to the present invention unexpectedly show an improved ability to be dyed with acid dyes and to be able to retain the dyes when they are washed, rinsed and exposed to sunlight. The polymer can be formed into durable, colored microporous coatings and other shaped objects and articles using some of the most efficient and economical methods.

The following examples are included to further illustrate the invention. All sizes are based on weight unless otherwise specified.

Example 1

This example describes the production of a clear, non-porous film of the new polymer with subsequent coloring of the film with an acidic dye.

A 20% solution of polyurethane elastomers is prepared by first mixing 3343 parts of polytetramethylene ether glycol with a molecular weight of approx. 1000 with 291 parts of tolylene-2,4-diisocyanate and then heat the mixture at 90° C. for 3 hours. 2485 parts of the resulting hydroxyl-terminated dimer are mixed with 570 parts of methylene bis-(4-phenyl isocyanate). The mixture is heated for one hour

at 80° C, which gives a pre-polymer with

isocyanate end groups. The pre-polymer is dissolved in 10,000 parts of N,N-dimethylformamide (also called dimethylformamide), and the resulting solution is added to

such as to a resolution consisting of 50

parts chain extender dissolved in 1710 parts dimethylformamide. The chain extender be-

consists of N-methyl-amino-bis-propylamine and hydrazine hydrate in the molar ratio 40 : 60.

The resulting reaction mixture is stirred

at 40°C for 30 minutes to form a polyurethane solution with a viscosity of

about. 115 poise and a polymer content of approx.

20 percent

A layer of the elastomeric solution

spread on a glass plate in sufficient thickness to form an approx. 0.5 mm thick film after drying. The drying is carried out by placing the coated glass plate in an oven at 100° C for 1 - 11/2 hours. The film is then cooled and removed from the plate.

A piece of the clear film. is held

immersed for 30 minutes in boiling water

dig dye bath containing 5% by weight acid red dye and 5% by weight oxalic acid intended for the film sample. The ratio between the weight of the sample and the weight of the dye bath is 1 : 40. The dye is the red chromed monoazo dye described in example

pel 10 in the French patent 942 500. It is prepared by diazotizing 2-amino-phenol-4-sulfonamide, coupling the diazotized intermediate with 1,3-isoquino-

lindol and metallizes the coupled mate-

rial with chrome.

The film is then washed for 15 minutes

in a boiling aqueous wash bath containing 0.3% by weight of a non-ionic cleaning agent intended for the water. The relationship between weight-

the thickness of the film and the weight of the bath are fast

set 1:40. The cleaning agent is the condensation product obtained by reacting 20 mol of ethylene oxide with 1 mol of a C-18 alcohol.

The dyed and washed film product

has a deep and uniform red colour. It is commonly used as a strong, stretchy, flexible, non-porous, colored polymer film,

for example for packaging, pulling furniture, baby clothes, elastic bands, be-

shooting moves, etc.

For comparison, a con-

troll test by the procedure according to ec-

example 1 but with the difference that one uses hydrazine hy-

dragged. When the control sample is removed from the

after dyeing, it is not red but pale amber.

Example 2

A black polyurethane film with equivalent

properties and area of application

as the product in example 1 is produced by the method in example 1 with the only exception that the dye in the dye

the bathroom is chromed monoazo black designated CI 15711 (Colour Index Number) in "Colour

Index, second edition, volume 3, copyright

1957 in the USA by the American Association of Textile Chemists and Colorants.

When the product in this example sub-

5 successive washing cycles are thrown, or a total washing time of 75 minutes, under

change of fresh bath for each cycle, be-

it essentially retains its original deep black colour. A control sample prepared with hydrazine as the only chain extender, on the other hand, practically lost all black color in a single washing cycle. The colored products made from the new polymer hair from which it appears a better washing fastness.

Similar results to those there

obtained in example 2 is also obtained when N-amino-bis-propylamine or N-methyl-amino-bis-ethylamine is used instead of N-methyl-amino-bis-propylamine

proportion of the chain extender in Example 2.

Claims (2)

1. Process for producing substantially linear polyurethane-poly- more with improved dyeability, with a molecular weight in the range 5000-300,000, and which is soluble in organic solvents, especially in dimethylformamide, whereby organic diisocyanates are reacted with polyalkylene ether glycols or with polyesters with hydroxyl end groups, and the reaction product obtained which has isocyanate end groups, the chain is extended using chain extenders with free amino groups, characterized in that a mixture of two compounds is used for the chain extension, namely: a) a compound in which two reactive hydrogen atoms are bound to amino nitrogen atoms, preferably hydrazine, and b) an amine of the formula in which R represents an alkyl group with from 1 to 4 carbon atoms, the two compounds a) and b) being used in a molar ratio of 95:5—50:50, preferably in the molar ratio 95:5—70:30. 2. Method according to claim 1, characterized in that the two components of the mixture used are N-methyl-amino-bis-propylamine and hydrazine.