Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Reexamination Certificate
1998-08-13
2003-04-01
Foelak, Morton (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Cellular products or processes of preparing a cellular...
C427S244000, C427S246000, C428S318400, C428S319100, C428S422800, C156S043000, C156S077000, C156S078000, C156S079000, C521S072000, C106S122000
Reexamination Certificate
active
06541528
ABSTRACT:
This invention is concerned with making flexible foams with chemical blowing agents and with substrates coated with the foams so produced.
BACKGROUND OF THE INVENTION
Chlorofluorocarbons have found use worldwide as blowing agents in the manufacture of polyurethane foams. However, the objection to the use of such compounds has required effort on the part of industry to produce environmentally less damaging alternatives.
It is known to employ solvents and solvent mixtures in polymeric compositions which will, under favorable conditions, act to foam said polymeric compositions. Rigid polyurethane foams have been produced in this way having end applications, for example, as insulating layers in construction panels, for refrigeration units and for lagging of pipes.
However, in application wherein a flexible foam is to be applied as coating to improve the handle and the aesthetic quality of a flexible substrate to which it is applied, for example, in the leather industry, solvent blowing agents have not been usefully employed as the requisite fineness and firmness of the foam for this application has not heretofore been obtainable.
Foams suitable for the application described in the preceding paragraph can be achieved by mechanical foaming techniques, however, some difficulty is encountered in the handling of such foams because of their instability.
It is desirable to form foams with solvent blowing agents which foams have the required firmness and fineness making them suitable for use as coatings for flexible substrates wherein said substrate is reliant upon the coating for its soft handle and aesthetic quality.
BRIEF SUMMARY OF THE INVENTION
It has now been found that certain organic solvents may be employed as blowing agents in polymeric compositions which are capable of forming a flexible coating on leather and leather substitutes.
DETAILED DESCRIPTION OF THE INVENTION
According to the invention there is provided a process for finishing leather and leather substitute substrates comprising the steps of:
a) applying to the surface of said substrate an aqueous polymeric composition (C) comprising an amount of solvent blowing agent boiling in the range of from 40 to 60° C., effective to foam said composition; and
b) applying heat to the coated substrate to foam and cure said polymeric composition (C) to form a flexible foam coating fixed to the substrate surface.
The aqueous polymeric composition (C), hereinafter referred to as composition (C), comprises a component (A) consisting of a polyurethane, a polyacrylic or polybutadiene resin or a mixture of such resins, optionally (B) at least one foam stabilizing component and the aforementioned blowing agent.
As component (A) there may be selected conventional polyurethanes which are useful in the formation of flexible foamed coatings, in particular those that are dispersible in water, principally those polyurethanes obtained by the reaction of dimethylolalkane carboxylic acids and diols, in particular macrodiols with diisocyanates and optionally diamino compounds.
The diisocyanates hereinabove mentioned are conventional and are preferably those in which at least a part thereof is aliphatic, e.g. open-chain aliphatic, cycloaliphatic or aliphatic having both open-chain and cycloaliphatic structure, and/or aromatic diisocyanates. The diisocyanates contain in the hydrocarbon radical, to which the two isocyanate groups are bound, advantageously 6 to 15 carbon atoms.
Aliphatic open-chain diisocyanates may be selected from, e.g. hexamethylenediisocyanate or trimethylhexylene-1,6-diisocyanate (in particular 2,2,4-trimethylhexylene-1,6-diisocyanate and 2,4,4-dimethylhexylene-1,6-diisocyanate). Cyclic diisocyanates may be selected from mono- and dicyclic diisocyanates, e.g. 2,4- or 2,6-tolylenediisocyanate, m-phenylenediisocyanate, xylylenediisocyanate, 4,4′-diphenylmethanediisocyanate, 3,3′-dimethyl-4,4′-diphenylmethanediisocyanate, dicyclohexylmethane-4,4′-, -4,2′- or -2,2′-diisocyanate wherein each cyclohexyl radical may optionally further bear a methyl group, 1,3-cyclohexylenediisocyanate, methyl substituted 1,3-cyclohexylenediisocyanate and isophoronediisocyanate.
The diols hereinabove mentioned are diols which are known to be useful in the preparation of polyurethanes to be dispersed in water and used in the production of flexible foams and are characteristically long chain diols. Principally, said diols are macrodiols, in particular polyetherdiols, polyesterdiols or polyesteretherdiols, among which polyalkyleneglycols are preferred, in particular polypropyleneglycols, polybutyleneglycols and mixed polypropylene- and -butyleneglycols. The polybutyleneglycols are principally those comprising oxygen-linked butylene-1,2-, -1,3-, 2,3- or -1,4-groups. Polypropyleneglycols and polybutyleneglycols, or corresponding mixed polyetherdiols, are principally addition products of the corresponding cyclic oxides (in particular oxiranes or tetrahydrofuran) to water or starting diols, which in particular contain 2 to 6 carbon atoms, e.g. ethyleneglycol, propyleneglycol, butyleneglycol, neopentylglycol or hexamethylenediol. Polypropyleneglycols are preferred.
The average molecular weight M
w
of the macrodiols is preferably in the range of 800 to 5000. By the suitable choice of the diols the properties of the polyurethanes may be influenced. A preferred group of diols is that of higher molecular weight macrodiols, in particular polyetherdiols with an average molecular weight M
w
in the range of 1000 to 5000, preferably 1200 to 4000, in particular 1500 to 3500.
Various diols having carboxy, sulfonic or ether groups can be employed for the production of ionomeric polyurethanes. In general, known carboxylic acids as are employed as carboxy-group-containing diols in the production of ionomeric carboxy-group-containing polyurethanes, in particular &agr;,&agr;-dimethylolalkane-carboxylic acids come into consideration. Principally they correspond to the formula
in which R signifies hydrogen or C
1-8
-alkyl.
Preferably R signifies hydrogen or C
1-4
-alkyl, in particular hydrogen or methyl.
Similarly, compounds containing sulfonic acid groups and 1,3-diols containing a polyether chain also come into consideration.
The molar ratio of the total non-ionogenic diols, in particular macrodiols, to the ionic-group-containing diol is advantageously in the range of 1:0.2 to 1:2, preferably in the range of 1:0.3 to 1:1.2.
Per mole of diol compounds employed (macrodiols and ionic-group-containing diols) there are employed advantageously 0.9 to 3 moles of diisocyanate compounds. If the diols and diisocyanates are reacted to form isocyanate terminated oligourethanes, which are then chain-extended with diamino compounds, the molar ratio of the diol compounds to the diisocyanate compounds is advantageously in the range of from 1:1.05 to 1:2.5, preferably 1:1.2 to 1:2.2.
The diamino compounds referred to above are known compounds and are principally aliphatic, saturated, open-chain or cyclic diamines with 2 to 10 carbon atoms in the aliphatic radical or also hydrazine, e.g. cyclohexylenediamine, isophoronediamine, ethylenediamine, propylene-1,2- or -1,3-diamine, hexamethylenediamine and 2,2,4- and/or 2,4,4-trimethylhexylene-1,6-diamine, among which the lower molecular weight open-chain diamines with 2 to 6 carbon atoms, in particular propylene-1,3-diamine and propylene-1,2-diamine, and isophoronediamine are preferred, or even hydrazine, the latter being preferably employed in the form of the hydrate.
The reaction of the isocyanate-terminated oligourethanes with the diamino-compounds takes place advantageously in aqueous medium, optionally in the presence of further diisocyanate. The diamino-compounds are advantageously employed in such amounts that there is achieved a reaction as complete as possible with respect of the available isocyanate groups. The chain extension reaction is carried out preferably to the extent that in the final product there are essentially no isocyanate groups or primary amino groups, i.e. to the extent that these group
Clariant Finance (BVI) Limited
Foelak Morton
Hanf Scott E.
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