Molecular sieve abstract
A substantially solvent-free fast low temperature curing polyurethane
coating composition is disclosed as well as a procedure for synthesizing
it and a procedure for applying it to a flexible substrate. It has
a long shelf-life yet cures in about 1 to 5 minutes at temperatures
of between about 80.degree. and 180.degree. C. to give a flexible
coating. The composition is a mixture of a polyisocyanate melting
at more than about 100.degree. C. and a hydroxyl bearing polyurethane
prepolymer based upon branched polyethers, monomeric glycols, and
polyamines made with a deficit of polyisocyanate. The composition
includes an isocyanate addition catalyst and a sodium aluminum silicate
type molecular sieve and may include a polyester polyol as an additive
or a reactant in forming the prepolymer.
Molecular sieve claims
What is claimed is:
1. A coating composition comprising
(A) about 5-30% by weight of a polyisocyanate having a melting
point above about 100.degree. C. and
(B) about 95-70% by weight of a polyhydroxyl compound, characterized
in that component (B) is a prepolymer containing hydroxyl groups
of
(a) a polyisocyanate,
(b) about 50 to 85% by weight, based on the sum of components (b)
to (e) of a partially branched polyether polyol having a molecular
weight of from about 1000 to 4500
(c) about 0 to 10% by weight of a polyester polyol having a molecular
weight of about 500 to 2000
(d) about 10 to 30% by weight of a glycol having a molecular weight
of from about 62 to 250 and
(e) about 0.5 to 5% by weight of a compound containing at least
two primary or secondary amino groups
wherein the equivalent ratio or component (a) to components (b)
to (e) lies between about 0.25 and 0.65 and wherein (B) contains
(f) about 1 to 4% by weight of a zeolite molecular sieve, and
(g) about 0.1 to 5% by weight of a catalyst for isocyanate addition
reactions.
2. Coating compositions according to claim 1 characterized in
that they comprise
(A) about 10 to 20% by weight of a diisocyanate having a melting
point above 125.degree. C. and
(B) about 80 to 90% by weight of a hydroxyl prepolymer which was
produced by reaction of
(a) a diisocyanate with
(b) about 65 to 80% by weight, based on the sum of components (b)
to (e), of a polyether polyol having an average hydroxyl functionality
of about 2.5 to 3 which is predominately contributed by secondary
hydroxyl groups and has a molecular weight of from about 2000 to
4000
(c) about 1 to 5% by weight of an adipic acid polyester having
a molecular weight of from about 700 to 1200
(d) about 15 to 25% by weight of a glycol having a molecular weight
of from about 76 to 150 and
(e) about 1 to 2% by weight of an aromatic diamine having a molecular
weight of below 200 wherein the equivalent ratio of (a) to the
sum of components (b) to (e) lies between about 0.35:1 and 0.6:1.
3. A substantially solvent-free process for preparing polyurethane
treated flexible substrates comprising
(A) coating the substrate with the composition of claim 1 and
(B) curing the coating composition at temperatures between about
80.degree. and 180.degree. C. for between about 1 and 5 minutes.
4. A process for preparing substantially solvent-free fast low
temperature curing coating compositions with long shelf-life comprising
(a) forming hydroxyl bearing prepolymer from:
(i) a polyisocyanate,
(ii) about 50 to 85 wt.%, based on the weight of ii to v, of a
branched polyether having an average hydroxyl functionality of between
about 2.5 and 3.0 and a Mn of between about 2000 and 4000
(iii) about 0 to 10 wt.%, based on the weight of ii to v, of a
polyester polyol having a Mn of between about 500 and 2000
(iv) about 10 to 30wt.%, based on the weight of ii to v, of a glycol
having a molecular weight of between about 62 and 250 and
(v) about 0.5 to 5 wt.%, based on the weight of ii to v, of a compound
containing at least two primary or secondary amino groups,
said polyisocyanate being present in sufficient quantity to give
a NCO to achieve hydrogen ratio of between about 0.25 and 0.65
(b) combining said prepolymer either before or after its synthesis
with
(i) about 1 to 4 wt.%, based on the weight of said prepolymer,
of a molecular sieve of the aluminum silicate type, and
(ii) about 0.1 to 5 wt.%, based on the weight of said prepolymer
of a catalyst for isocyanate addition reactions, and
(c) after synthesis of said prepolymer mixing it with about 5 to
30 wt.%, based on the weight of prepolymer and this component, of
a polyisocyanate having a melt point above about 100.degree. C.
Molecular sieve description
FIELD OF THE INVENTION
This invention relates to improved, substantially solvent-free
polyurethane reactive systems which can be used in doctor coating
processes and which have a long pot-life, which systems are suitable
for the coating of fabrics or other substrates.
BACKGROUND OF THE INVENTION
A process for coating fabric tubes is known from German Auslegeschrift
No. 1504690 in which polymeric solutions are initially doctored
onto the fabric in a thin layer and the coatings are subsequently
dried by heating the tube. This process does, however, have two
serious disadvantages. The tube has to be heated from the inside
in order to impart a bubble-free surface to the fabric coating and
this means an additional outlay on apparatus. Moreover, the presence
of solvents makes processing more difficult since numerous measures
have to be taken to suck off the solvent vapors, and processing
plants which are protected from explosion are needed.
A process for coating fabric tubes with solvent-free systems (application
of a polymer melt) is described in German Pat. No. 1778877. A
disadvantage of this process is the high temperatures of about 200.degree.
C. needed for processing thermoplastic materials. The melt bath,
pipe work and stripping apparatus have to be kept at this high temperature
level. In addition, the deeper penetration of the plastic coating
into the fabric induced by the process causes marked stiffening
of the material so that the finished tube becomes more difficult
to handle.
Solvent-free reactive polyurethane compositions for coating fabrics,
which are stable in storage, are described in German Offenlegungsschrift
No. 157048 and U.S. Pat. No. 3475200 and are composed of polyhydroxyl
compounds, uretdione diisocyanates which melt above 100.degree.
C. and chain extenders which melt above 80.degree. C. Although coating
pastes of this type are stable in storage over relatively long periods
of time, they need uneconomically long reaction times (for example,
90 minutes at 110.degree. C.) in order to cure completely.
The object of the invention is therefore to avoid the disadvantages
described above of the known processes for coating fabrics--presence
of solvent; too short pot-life; high processing temperatures and
long curing times and simultaneously to allow simple and problem-free
handling of the coating compositons.
This object is achieved by the polyurethane systems provided according
to the invention.
SUMMARY OF THE INVENTION
The present invention relates to substantially solvent-free coating
compositions which can be doctor-coated, comprising
(A) about 5 to 30% by weight, preferably about 10 to 20% by weight
of a polyisocyanate having a melting point above about 100.degree.
C., preferably above about 130.degree. C., and
(B) about 95 to 70% by weight, preferably about 90 to 80% by weight
of a polyhydroxyl compound,
which are characterized in that component (B) represents a prepolymer,
containing hydroxyl groups, prepared from
(a) a polyisocyanate,
(b) about 50 to 85% by weight preferably about 65 to 80% by weight,
based on the sum of components b) to e), of a partially branched
polyether polyol having a molecular weight of from about 1000 to
4500 preferably from about 2000 to 4000 particularly preferably
about 3500
(c) about 0 to 10% by weight, preferably about 1 to 5% by weight,
of a polyester polyol having a molecular weight of from about 500
to 2000 preferably from about 700 to 1200
(d) about 10 to 30% by weight, preferably about 15 to 25% by weight,
of a glycol having a molecular weight of from about 62 to 250 preferably
from about 76 to 150 and,
(e) about 0.5 to 5% by weight, preferably about 1 to 2% by weight,
of a compound containing at least two amino groups and having a
molecular weight preferably below about 200
wherein the equivalent ratio of component (a) to components (b)
to (e) lies between about 0.25 and 0.65 preferably between about
0.35 and 0.60 particularly preferably between about 0.50 and 0.55
and wherein component (B) contains (f) about 1 to 4% by weight of
a molecular sieve of the sodium aluminum silicate type and
(g) about 0.1 to 5% by weight of an activator.
DETAILED DESCRIPTION OF THE INVENTION
Components A) and B) are preferably used in such proportions that
the NCO/OH equivalent ratio including any masked NCO groups, which
may be contained in component A) lies between about 0.9:1 and 1.5:1
particularly preferably between about 1.0:1 and 1.1:1.
The coating systems according to the invention have a very long
pot-life and a relatively short curing time.
For the proposed applications of the reactive systems according
to the invention, it is necessary for the criteria listed above
with regard to the composition of component (B) to be observed.
If a polyether of linear structure is used instead of the partially
branched polyether b), then uneconomically long curing times are
obtained (Example 3). Polyethers containing predominantly secondary
hydroxyl groups at the end of the chain are preferred since primary
polyether polyols lead to too great a shortening of the pot-life
(Example 4).
The addition of the polyester polyol c) is preferred according
to the invention, since the viscosity of the paste would otherwise
increase 24 hours after stirring in the solid diisocyanate (A) to
such an extent that it would be extremely difficult or even impossible
to process the mixture (Example 6).
The polyester polyol (c) does not however need to be chemically
incorporated into the hydroxyl group containing prepolymer (B);
it can also be added to the mixture of (A) and (B) as a third component.
It is necessary to incorporate a small amount of an amino-functional
compound (e) in order to allow finely dispersed distribution of
the rigid segment formed from short-chained glycol (d) and polyisocyanate
(a). If the hydroxyl prepolymer is produced without the addition
of diamine, coarse-particled suspensions which deposit sediments
are obtained and these suspensions do not react in a reproducible
manner and lead to a marked deterioration in the mechanical properties
(Example 5).
It is necessary to add molecular sieves (f) in order to obtain
bubble-free coatings. In addition, the storage stability of the
finished coating paste is clearly improved. Coating pastes produced
without the addition of molecular sieve (f) exhibit less storage
stability at elevated temperatures. Example 7 illustrates this situation.
If the preliminary chain lengthening with the polyisocyanate (a)
is omitted, acceptable processing times are obtained, but the coating
turns out to be very soft and tacky and is unsuitable for practical
purposes (Example 8).
Any polyisocyanates known per se (preferably diisocyanates) having
a melting point above 100.degree. C., preferably between 125.degree.
and 200.degree. C., are suitable as component (A) of the coating
compositions according to the invention. Examples of suitable polyisocyanates
include 14-dichloro-25-diisocyanato-benzene; 1-chloro-4-methoxy-25-diisocyanato-benzene;
13-dimethoxy-46-diisocyanato-benzene; 33'-dimethoxy-44'-diisocyanato
biphenyl; 252',5'-tetramethyl-44'-diisocyanatodiphenyl methane;
diphenyl sulphone 44'-diisocyanate; naphthylene-15-diisocyanate
and the urea diisocyanate from 1 mol water and 2 mol 24-toluylene
diisocyanate, the last three diisocyanates mentioned being preferred.
Diisocyanates containing one uretdione group, of the type formed
by dimerization known per se of the polyisocyanates known in polyurethane
chemistry are preferred according to the invention because they
are solid polyisocyanates having a high melting point. Dimeric 24-toluylene
diisocyanate is particularly preferred.
All polyisocyanates known per se are in principle suitable for
use as isocyanate component a) in the production of the OH-prepolymer
(component B) of the reactive systems according to the invention.
These include aliphatic, cycloaliphatic, araliphatic, aromatic and
heterocyclic polyisocyanates of the types described, for example,
by W. Siefken in Justus Liebigs Annalen der Chemie, 562 pages 75
to 136 for example those corresponding to the formula
in which
n=2 to 4 preferably 2 and
Q represents an aliphatic hydrocarbon radical containing 2 to 18
preferably 6 to 10 carbon atoms; a cycloaliphatic hydrocarbon radical
containing 4 to 15 preferably 5 to 10 carbon atoms;
an aromatic hydrocarbon radical containing 6 to 15 preferably 5
to 13 carbon atoms or an araliphatic hydrocarbon radical containing
8 to 15 preferably 8 to 13 carbon atoms, for example, ethylene
diisocyanate; 14-tetramethylene diisocyanate; 16-hexamethylene
diisocyanate; 112dodecane diisocyanate; cyclobutane-13-diisocyanate;
cyclohexane-13- and 14-diisocyanate and mixtures of these isomers;
1-isocyanato-335-trimethyl-5-isocyanato methylcyclohexane (German
Auslegeschrift No. 1202785 and U.S. Pat. No. 3401190 incorporated
herein by reference), 24- and 26-hexahydrotoluylenediisocyanate
and mixtures of these isomers, hexahydro-13- and/or -14-phenylene
diisocyanate, perhydro-24'- and/or -44'-diphenyl methane diisocyanate;
13- and 14-phenylene diisocyanate; 24- and 26-toluylene diisocyanate
and mixtures of these isomers; diphenyl methane 24'- and/or -44'-diisocyanate
and naphthylene-15-diisocyanate.
Other suitable materials according to the invention include, for
example: triphenylmethane-44',4"-triisocyanate; polyphenyl:polymethylene
polyisocyanates of the type which can be obtained by aniline-formaldehyde
condensation and subsequent phosgenation and which are described,
for example, in British Pat. Nos. 874430 and 848671; m- and p-isocyanatophenylsulphonyl
isocyanates according to U.S. Pat. No. 3454606 incorporated herein
by reference; perchlorinated aryl polyisocyanates of the type described
for example, in German Auslegeschrift No. 1157601 (U.S. Pat. No.
3277138 incorporated herein by reference); polyisocyanates containing
carbodiimide groups of the type described in German Pat. No. 1092007
(U.S. Pat. No. 3152162 incorporated herein by reference) and in
German Offenlegungsschriften Nos. 2504400; 2537685 and 2552350;
norbornane-diisocyanates according to U.S. Pat. No. 3492330 incorporated
herein by reference; polyisocyanates containing allophanate groups
of the type described, for example, in British Pat. No. 994890
Belgian Pat. No. 761626 and Netherlands Pat. Application No. 7102524;
polyisocyanates containing isocyanurate groups of the type described,
for example, in U.S. Pat. No. 3001973 incorporated herein by reference,
German Pat. Nos. 1022789 1222067 and 1027394 and German Offenlegungsschriften
Nos. 1929034 and 2004048; polyisocyanates containing urethane
groups of the type described, for example in Belgian Pat. No. 752261
or U.S. Pat. Nos. 3394164 and 3644457 both incorporated herein
by reference; polyisocyanates containing acrylated urea groups according
to German Pat. No. 1230778; polyisocyanates containing biuret
groups of the type described, for example, in U.S. Pat. Nos. 3124605
and 3201376 both incorporated herein by reference and British
Pat. No. 889050; polyisocyanates produced by telomerization reactions
of the type described, for example, in U.S. Pat. No. 3654106 incorporated
herein by reference; polyisocyanates containing ester groups of
the type listed, for example, in British Pat. Nos. 965474 and 1072956;
U.S. Pat. No. 3567763 incorporated herein by reference and German
Pat. No. 1231688 reaction products of the above-mentioned isocyanates
with acetylene according to German Pat. No. 1072385 and polyisocyanates
containing polymeric fatty acid esters according to U.S. Pat. No.
3455883 incorporated herein by reference.
It is also possible to use the distillation residues produced during
the commerical production of isocyanate and containing isocyanate
groups, which may be dissolved in one or more of the above-mentioned
polyisocyanates. Moreover, it is possible to use mixtures of the
abovementioned polyisocyanates.
The polyisocyanates which are easy to obtain commercially are generally
preferred, for example, 24- and 26-toluylene diisocyanate as well
as mixtures of these isomers ("TDI"), polyphenyl-polymethylene
polyisocyanates, of the type produced by aniline formaldehyde condensation
and subsequent phosgenation ("crude MDI") and polyisocyanates
containing carbodiimide groups, urethane groups, allophanate groups,
isocyanurate groups, urea groups or biuret groups ("modified
polyisocyanates"), in particular those modified polyisocyanates
which are derived from 24- and/or 26-toluylene diisocyanates or
from 44'- and/or 24'-diphenyl methane diisocyanate.
The isomeric toluylene diisocyanates are particularly preferred.
Partially branched polyether polyols are used as component b) with
the structure of the hydroxyl prepolymer B), these partially branched
polyether polyols preferably having an average hydroxyl functionality
of from about 2.5 to 3.0 and an average molecular weight (Mn) of
from about 2000 to 4000 particularly preferably about 3500. These
polyethers containing hydroxyl groups are those of the type known
per se and are produced, for example, by the polymerization of epoxides
such as ethylene oxides, propylene oxide, butylene oxide, tetrahydrofuran,
styrene oxide or epichlorohydrin with themselves, for example, in
the presence of Lewis catalysts such as boron trifluoride or by
the addition of these epoxides, preferably of propylene oxide, either
as a mixture or successively, to starting components containing
reactive hydrogen atoms such as water, alcohols, ammonia or amines,
for example, ethylene glycol, propylene glycol-(13) or -(12),
trimethylol propane, glycerol, sorbitol 44'-dihydroxydiphenylpropane,
aniline, ethanol amine or ethylene diamine. Polyethers started on
formitol or formose (German Offenlegungsschriften Nos. 2639083
or 2737951) can also be used according to the invention. Those
polyethers which predominantly (more than 90 % by weight, based
on all the hydroxyl groups present in the polyether) contain secondary
hydroxyl groups, are preferred.
The polyesters containing hydroxyl groups which can be used as
components (c) in the structure of the hydroxyl prepolymer include,
for example, reaction products of polyhydric, preferably dihydric,
optionally additionally trihydric alcohols with polyvalent, preferably
divalent carboxylic acids. The corresponding carboxylic acid anhydrides
or corresponding polycarboxylic acid esters of lower alcohols or
their mixtures can be used instead of free polycarboxylic acids,
to produce the polyesters. The polycarboxylic acids can be aliphatic,
cycloaliphatic, aromatic and/or heterocyclic and may be substituted,
for example by halogen atoms and/or be unsaturated.
Examples of such carboxylic acids and derivatives thereof include:
Succinic acid, adipic acid, suberic acid, azelaic acid, sebacic
acid, phthalic acid, isophthalic acid, trimellitic acid, phthalic
acid anhydride, tetrahydrophthalic acid anhydride, hexahydrophthalic
acid anhydride, tetrachlorophthalic acid anhydride, endomethylene
tetrahydrophthalic acid anhydride, glutaric acid anhydride, maleic
acid, maleic acid anhydride, fumaric acid, dimerized and trimerized
unsaturated fatty acids, which may be mixed with monomeric unsaturated
fatty acids such as oleic acid, terephthalic acid dimethyl ester
and terephthalic acid bis-glycol ester. Suitable polyhydric alcohols
include, for example, ethylene glycol, propylene glycol-(12) and
-(13), butylene glycol-(14) and -(23), hexane diol-(16), octane
diol-(18), neopentyl glycol, 14-bis-hydroxy methyl cyclohexane,
2-methyl-13-propane diol, glycerol, trimethylol propane, hexane
triol-(126), butane triol-(124), trimethylol ethane, pentaerylthrol,
quinitol, mannitol and sorbitol, formitol, methyl glycoside, also
diethylene glycol, triethylene glycol, tetraethylene glycol and
higher polyethylene glycols, dipropylene glycol and higher polypropylene
glycols as well as dibutylene glycol and higher polybutylene glycols.
The polyesters may contain a proportion of terminal carboxy groups.
Polyesters derived from lactones, for example, .epsilon.-caprolactone,
or from hydroxycarboxylic acid, for example, .omega.-hydroxycapronic
acid, can also be used.
Polyesters of adipic acid and ethylene glycol, propylene glycol
or butane diol, in particular polypropylene glycol adipates are
preferred. Castor oil can also be used as polyester component (c).
Representatives of the said compounds to be used according to the
invention are described, for example, in High Polymers, Vol. XVI,
"Polyurethanes Chemistry and Technology" written by Saunders-Frisch,
Interscience Publishers, New York, London, Volume I, 1962 pages
32 to 42 and pages 44 to 54 and Volume II, 1964 pages 5 to 6 and
198 to 199 and in Kunststoff-Handbuch, Volume VII, Vieweg-Hochtlen,
Carl-Hanser-Verlag, Munich, 1966 for example on pages 45 to 71.
Glycols d) of lower molecular weight which are suitable for the
production of the prepolymer component B) include, for example:
ethylene glycoll propylene glycol(12) and -(13), butylene glycol-(14)
and -(23), pentane diol-(15), hexane diol-(16), octane diol-(18),
neopentyl glycol, 14-bis-hydroxy methyl cyclohexane, 2-methyl-13-propane
diol, dibromobutene diol; diethylene glycol, triethylene glycol,
tetraethylene glycol, higher polyethylene glycols having a molecular
weight of up to about 250 dipropylene glycol, higher polypropylene
glycols having a molecular weight of up to about 250 dibutylene
glycol, 44'-dihydroxy diphenyl propane, di-hydroxy methyl-hydroquinone,
diethanol amine and N-methyldiethanol amine.
Ester diols corresponding to the following general formulae are
other lower molecular diols which are suitable according to the
invention and have a molecular weight of up to about 250:
and
in which
R represents an alkylene radical containing 1 to 10 preferably
2 to 6 carbon atoms or a cycloalkylene or arylene radical with 6
to 10 carbon atoms;
x=2-6 and
y=3-5
for example, .delta.-hydroxybutyl-.epsilon.-hydroxy-capronic acid
ester; .omega.-hydroxyhexyl-.gamma.-hydroxybutyric acid ester; adipic
acid-bis-(.beta.-hydroxyethyl) ester and terephthalic acid-bis-(.beta.-hydroxyethyl)
ester. Diolurethanes corresponding to the general formula
in which
R' represents an alkylene radical containing 2 to 15 preferably
2 to 6 carbon atoms or a cycloalkylene or arylene radical containing
6 to 15 carbon atoms and
x represents a number between 2 and 6 for example, 16-hexamethylene-bis-(.beta.-hydroxyethylurethane)
or 44'-diphenylmethane-bis-(.delta.-hydroxybutylurethane); as well
as diol ureas corresponding to the general formula ##STR1## in which
R" represents an alkylene radical containing 2 to 15 preferably
2 to 9 carbon atoms or a cycloalkylene or arylene radical containing
6 to 15 carbon atoms,
R'" represents hydrogen or a methyl group and
x represents the numbers 2 or 3 for example, 44'-diphenylmethane-bis-(.beta.-hydroxyethyl
urea) or the compound ##STR2##
Diols (d) which are preferred according to the invention include
diethylene glycol, triethylene glycol, propylene glycol, dipropylene
glycol and tripropylene glycol. Dipropylene glycol is particularly
preferred.
It is essential to the invention that a small amount (about 0.5
to 5% by weight, preferably about 1 to 2% by weight, based on the
sum of the compounds which are reactive towards isocyanates) of
an amino-functional compound, for example, a polyamine (preferably
an aromatic diamine), hydrazine or hydrazide is also used during
the production of the OH-prepolymer.
Aliphatic diamines which are suitable for use according to the
invention include for example, ethylene diamine; 14-tetramethylene
diamine; 111-undecamethylene diamine; 112-dodecamethylene diamine
and mixtures thereof; 1-amino-335-trimethyl-5-aminomethyl cyclohexane
("isophorone diamine") 24- and 26-hexahydrotoluylene
diamine and mixtures thereof; perhydro-24'- and 44'-diaminodiphenyl
methane; p-xylylene diamine, bis-(3-aminopropyl)-methyl amine; diaminoperhydroanthrazenes
(German Offenlegungsschrift No. 2638731) and cycloaliphatic triamines
according to German Offenlegungsschrift No. 2614244. Hydrazine,
and substituted hydrazines, for example methyl hydrazine, N,N'-dimethylhydrazine
and homologues thereof as well as acid dihydrazides can also be
used according to the invention, for example carbodihydrazides;
oxalic acid dihydrazide; the dihydrazides of malonic acid; succinic
acid; glutaric acid; adipic acid, .beta.-methyl adipic acid, sebacic
acid, hydracrylic acid and terephthalic acid; semicarbazido-alkylene-hydrazides
such as, for example, .beta.-semicarbazido propionic acid hydrazide
(German Offenlegungsschrift No. 1770591), semicarbazido alkylene
carbazine esters such as, for example, 2-semi-carbazido ethyl carbazinester
(German Offenlegungsschrift No. 1918504) or also amino semi-carbazide
compounds such as, for example, .beta.-amino-ethyl-semicarbazido-carbonate
(German Offenlegungsschrift No. 1902931).
Examples of aromatic diamines include bisanthranilic acid esters
according to German Offenlegungsschriften Nos. 2040644 and 2160590;
35- and 24-diamino benzoic acid ester according to German Offenlegungsschrift
No. 2025900; diamines containing ester groups, described in German
Offenlegungsschriften Nos. 1803635 (U.S. Pat. Nos. 3681290 and
3736350 both incorporated herein by reference), 2040650 and
2160589 the diamines containing ether groups according to German
Offenlegungsschriften Nos. 1770525 and 1809172 (U.S. Pat. Nos.
2654364 and 3736295 both incorporated herein by reference);
2-halogen-13-phenylene diamines which may be substituted in the
5-position (German Offenlegungsschriften Nos. 2001772 2025896
and 2065869), 33'-dichloro-44'-diamino-diphenyl methane, toluylene
diamine, 44'-diaminodiphenyl methane, 44'-diamino-diphenyl disulphides
(German Offenlegungsschrift No. 2404976), diamino-diphenyl dithioether
(German Offenlegungsschrift No. 2509404), aromatic diamines substituted
by alkylthio groups (German Offenlegungsschrift No. 2638760),
diaminobenzene phosphonic acid ester (German Offenlegungsschrift
No. 2459491), aromatic diamines containing sulphonate or carboxylate
groups (German Offenlegungsschrift No. 2720166), and the diamines
having high melting points listed in German Offenlegungsschrift
No. 2635400. The amino alkyl thioanilines according to German
Offenlegungsschrift No. 2734574 are examples of aliphatic-aromatic
diamines. Toluylene diamines which are substituted at the nucleus
with methyl and/or ethyl groups such as, for example, 35-diethyl-24-diamino
toluene are preferred.
The zeolites which are commercially available as molecular sieves
for example, are used according to the invention as sodium aluminum
silicates f).
Suitable activators g) according to the invention include polyurethane
catalysts of the type known per se, for example, tertiary amines,
such as triethyl amine; tributyl amine; N-methyl morpholine; N-ethyl
morpholine; N,N,N',N'-tetramethyl-ethylene diamine; pentamethyldiethylene
triamine and higher homologues (German Offenlegungsschriften Nos.
2624527 and 2624528), 14-diazabicyclo-(222)-octane; N-methyl-N'-dimethylaminoethyl
piperazine; bis-(dimethylaminoalkyl)-piperazines, (German Offenlegungsschrift
No. 2636787); N,N-dimethylbenzyl amine; N,N-dimethylcyclohexyl
amine; N,N-diethylbenzyl amine; bis-(N,N-diethylaminoethyl)-adipate;
N,N,N',N'-tetramethyl-13-butane diamine; N,N-dimethyl-.beta.-phenyl-ethyl
amine, 12-dimethyl imidazole, 2-methyl imidazole, monocyclic and
bicyclic amidines, (German Offenlegungsschrift No. 1720633), bis-(dialkylamino)
dialkyl ether (U.S. Pat. No. 3330782; German Auslegeschrift No.
1030558; German Offenlegungsschriften Nos. 1804361 and 2618280)
and tertiary amines containing amide groups (preferably formamide
groups) according to German Offenlegungsschriften Nos. 2523633
and 2732292. Suitable catalysts include Mannich bases known per
se of secondary amines such as dimethyl amine and aldehydes, preferably
formaldehyde, or ketones such as acetone, methylethyl ketone or
cyclohexanone and phenols such as phenol, nonylphenol or bisphenol.
Tertiary amines containing hydrogen atoms which are active toward
isocyanate groups, as catalysts include for example, triethanol
amine, triisopropanol amine, N-methyl-diethanol amine, N-ethyl-diethanol
amine, N,N-dimethyl-ethanol amine, the reaction products thereof
with alkylene oxides such as propylene oxide and/or ethylene oxide
as well as secondary tertiary amines according to German Offenlegungsschrift
No. 2732292.
Suitable catalysts also include sila-amines with carbon-silicone
bonds of the type described, for example, in German Pat. No. 1229290
(corresponding to U.S. Pat. No. 3620984 incorporated herein by
reference), for example, 224-trimethyl-2-sila-morpholine and 13-diethyl
amino methyl-tetramethyl-disiloxane.
Nitrogen-containing bases such as tetraalkyl ammonium hydroxides,
alkali metal hydroxides such as sodium hydroxide, alkali metal phenolates
such as sodium phenolate or alkali metal alcoholates such as sodium
methylate can also be used as catalysts. Hexahydratriazines can
also be used as catalysts (German Offenlegungsschrift No. 1769043).
The reaction between NCO-groups and Zerewitinoffactive hydrogen
atoms is greatly accelerated by lactams and azalactams, an association
between the lactam and the compound with acidic hydrogen initially
being formed. Associations of this type and their catalytic effect
are described in German Offenlegungsschriften Nos. 2062288; 2062289;
2117576 (U.S. Pat. No. 3758444 incorporated herein by reference);
2129198; 2330175 and 2330211.
Organometallic compounds in particular organotin compounds, can
be used as catalysts according to the invention. In addition to
sulphur-containing compounds such as di-n-octyl tin mercaptide (German
Auslegeschrift No. 1769367; U.S. Pat. 3645927 incorporated herein
by reference), it is preferred to use as organo-tin compounds the
tin (II) salts of carboxylic acids such as tin (II)acetate, tin(II)-octoate,
tin(II)-ethyl hexoate and tin(II)laurate and tin(IV)-compounds,
for example dibutyl tin oxide, dibutyl tin dichloride, dibutyl tin
diacetates, dibutyl tin dilaurate, dibutyl tin maleate or dioctyl
tin diacetate.
All the above-mentioned catalysts can of course be used as mixtures.
Combinations of organic metal compounds, in particular metal salts
of carboxylic acids (for example the Pb-salt of 2-ethyl hexanic
acid) with amine catalysts such as diazabicyclo octane are of particular
interest. Catalyst combinations of this type lead to coating compositions
having a particularly long pot-life at room temperature but still
having a short curing time when heated (for example, three minutes
at 100.degree. C.).
Other examples of catalysts which can be used according to the
invention and details about the mode of operation of the catalysts
are described in Kunststoff-Handbuch, Volume VII, edited by Vieweg
and Hochtlen, Carl-HanserVerlag, Munich 1966 for example on pages
96 to 102.
Surface-active additives such as emulsifiers can also be used according
to the invention. Suitable emulsifiers include for example, the
sodium salts of castor oil sulphonates or salts of fatty acids with
amines such as oleic acid diethyl amine or stearic acid diethanol
amine. Alkali or ammonium salts of sulphonic acids such as those
of dodecyl benzene sulphonic acid or dinaphthyl methane disulphonic
acid or of fatty acids such as ricinoleic acid or of polymeric fatty
acids can also be used as surface-active additives.
Reaction retarders can also be used according to the invention,
if desired, for example, acid reacting materials such as hydrochloric
acid or organic acid halides, as can cell regulators of the type
known per se such as paraffins, fatty alcohols or dimethyl polysiloxanes
as well as pigments or dyestuffs and flame retardants of the type
known per se, for example tris-chloroethyl phosphate, tricresyl
phosphate or ammonium phosphate and poly-phosphate. Stabilizers
against the influences of ageing and weathering, plasticizers and
substances having a fungistatic and bacteriostatic effect as well
as fillers such as barium sulphate, kieselguhr, carbon black or
whiting can also be used.
Other examples of surface-active additives and foam stabilizers
as well as cell regulators, reaction retarders, stabilizers, flame
retarding substances, plasticizers, dyestuffs and fillers as well
as fungistatically and bacteriostatically acting substances which
can be used according to the invention as well as details about
modes of application and operation of these additives are described
in Kunststoff-Handbuch, Volume VII, edited by Vieweg and Hochtlen,
Carl-HanserVerlag, Munich 1966 for example on pages 103 to 113.
In order to produce the components B) of the coating compositions
according to the invention, the compounds A) to e) described in
detail above are reacted together in a one-shot process at a NCO/(OH+NH)-equivalent
ratio of about 0.25:1 to 0.65:1 preferably about 0.35:1 to 0.60:1
particularly preferably about 0.50:1 to 0.55:1. As mentioned above,
the polyester polyol (c) which may be used simultaneously can also
be added only to the finished OH prepolymer. The components (f)
and (g) are preferably also used during the production of the OH
prepolymer, but they can also be mixed with the finished OH prepolymer
(B) and the solid polyisocyanate (A)--as can other additives which
may be used.
The polyurethane reactive systems according to the invention which
are stable in storage are suitable for coating a wide variety of
substrates. In addition to flat textile substrates, fabric tubes
can also preferably be coated by means of coating installations
known per se.
In order to provide the support material, for example, a polyester
fabric, with the polyurethane coating according to the invention,
the coating composition is applied to the support in the desired
thickness of the layer, for example by means of a doctor, brush,
roller, or the like. The method of application is not subject to
any restrictions because of the extremely long pot-life of the systems.
There is no risk of the doctor gelling or curing.
After application, the support material provided with the coating
can, for example, be passed through a heating duct, guided over
a heating table or drawn through an IR field for the curing process.
This operation can be performed, for example, at temperatures between
about 80.degree. and 180.degree. C., depending upon the thermal
load which the substrate to be coated can withstand. The setting
times of the coating accordingly lie between about 1 and 5 minutes.
The coating operation can be performed both horizontally and vertically
owing to the excellent intrinsic viscosity of the polyurethane systems,
without compositions applied running in the heat.
The following examples illustrate the present invention. The references
to quantities should be understood as parts by weight or percentage
by weight unless otherwise stated.
EXAMPLE 1
In order to produce a hydroxyl-terminated prepolymer, 80 parts
of a partially branched polypropylene glycol (OH No: 42 functionality
f=2.75)
20 parts dipropylene glycol,
5 parts Na-Al-silicate (a 50% suspension in the above-mentioned
polyether),
2 parts polypropylene glycol adipate (molecular weight: 820),
1 part 4-methyl-26-diethyl-13-diamino benzene and
0.5 parts diazabicyclooctane (33% in dipropylene glycol) with
18 parts 24-toluylene diisocyanate are reacted with constant stirring.
The reaction temperature increases to about 60.degree. C. in the
process. The reaction is terminated after about 1 hour.
17 parts dimeric 24-toluylene diisocyanate are incorporated into
100 parts of this OH prepolymer in a suitable mixer or by means
of rubbing-in roller at room temperature. 1% of an activator mixture
consisting of 88% diazabicyclooctane (33% in dipropylene glycol)
and 12% lead octoate (24% in white spirit) are subsequently stirred
into the mixture produced.
The paste produced in this way is storage stable for several months
at room temperature. The storage stability lasts for two weeks at
50.degree. C. The mixture sets within 1 to 3 minutes when heated
to 100.degree. C. The paste can optionally be dyed using suitable
color pigments.
The following physical values were determined on the cured polyurethane:
Density--1065 Mg/m.sup.3
Shore hardness A (DIN 53505)--81
Tensile strength (DIN 53504)--7.23 mPa
Breaking elongation (DIN 53504)--100%
Abrasion (DIN 53516)--141 mm.sup.3.
EXAMPLE 2
The following process was adopted for the production of a more
rigid coating material:
80 parts of the polyether from Example 1
20 parts propylene glycol-12
5 parts Na-Al-silicate (50% suspension in the above-mentioned polyether),
2 parts of the polypropylene glycol adipate from Example 1
1.5 parts diethyltoluylene diamine and
0.5 parts diazabicyclooctane (33% in dipropylene glycol)
are reacted with 27 parts 24-toluylene diisocyanate with stirring.
The reaction temperature increases to from 80.degree. to 100.degree.
C. depending upon the quantity of mixture.
After cooling, 24 parts dimeric 24-toluylene diisocyanate are
incorporated into 100 parts of the hydroxylterminated prepolymer
thus obtained, as described in Example 1.
The mixture is subsequently activated as in Example 1. This reactive
paste is also stable in storage for months at room temperature,
but cures within 1 to 3 minutes at 100.degree. C.
Test data measured on fully reactive material:
Density--1035 Mg/m.sup.3
Shore hardness A/D--89/40
Tensile strength--12.06 mPa
Breaking elongation--208%
Elasticity--26%
Abrasion--184 mm.sup.3
EXAMPLE 3 (Comparison Experiment)
Production of a hydroxyl-terminated prepolymer with a linear polyether:
80 parts of linear polypropylene glycol (OH No:56),
20 parts dipropylene glycol,
5 parts Na-Al-silicate (50% suspension in the polyether from Example
1),
2 parts of the polypropylene glycol adipate from Example 1
1 part diethyl toluylene diamine and
0.5 parts diazabicyclooctane (33% in dipropylene glycol)
are reacted with 17 parts toluylene diisocyanate, as in the preceding
examples.
20 parts dimeric toluylene diisocyanate are incorporated into 100
parts of this prepolymer.
The resulting paste cures with the same activation after only 10
minutes at 100.degree. C., using the activator mixture described
in Example 1. The surface remains tacky.
EXAMPLE 4
80 parts of a trifunctional ethoxylated polypropylene oxide with
terminal primary hydroxyl groups (OH No:36)
20 parts dipropylene glycol,
5 parts Na-Al-silicate (as 50% suspension in the polyether from
Example 1),
2 parts polypropylene glycol adipate,
1 part diethyl toluylene diamine and
0.5 parts diazabicyclooctane (33% in dipropylene glycol)
are reacted with 17 parts toluylene diisocyanate.
A paste is subsequently produced using 18 parts of the dimeric
24-toluylene diisocyanate on 100 parts of the prepolymer. After
activation using 1% activator mixture according to Example 1 thorough
curing is achieved within 20 seconds at 100.degree. C. However,
the paste is only stable in storage for about eight hours at room
temperature.
EXAMPLE 5 (Comparison Experiment)
80 parts of the polyether from Example 1
20 parts dipropylene glycol,
5 parts Na-Al-silicate (as 50% suspension in the polyether from
Example 1),
2 parts polypropylene glycol adipate and
0.5 parts glycol and 0.5 parts diazabicyclooctane (33% in dipropylene
glycol)
are reacted with 17 parts toluylene diisocyanate.
The recipe corresponds to the one according to Example 1 but without
the diamine. Shortly after the isocyanate has been stirred in, the
urethane rigid segment formed precipitates in granular form. The
subsequent processing with dimeric isocyanate does not lead to a
homogeneous final product.
EXAMPLE 6 (Comparison Experiment)
Example 2 is repeated without using the polyester polyol:
The viscosity of the mixture of hydroxyl-prepolymer and dimeric
toluylene diisocyanate increases greatly after only a few hours
so that the material can no longer be processed.
EXAMPLE 7 (Comparison Experiment)
Example 1 is repeated without zeolite.
After mixing the hydroxyl prepolymer with dimeric toluylene diisocyanate
and activation, a paste is obtained which is stable in storage for
about four weeks at room temperature. The stability at 50.degree.
C. is about 3 days. When the coating composition is heated, gas
is formed in an uncontrolled manner and spongy elastomers are obtained.
EXAMPLE 8 (Comparison Experiment)
Reaction of a polyol mixture with dimeric isocyanate without preliminary
chain-lengthening with monomeric toluylene diisocyanate:
80 parts of the polyether from Example 1
20 parts dipropylene glycol,
5 parts Na-Al-silicate (50% suspension in the polyether),
1 part diethyl toluylene diamine according to Example 1
0.5 parts diazabicyclooctane (33% in dipropylene glycol)
are mixed homogeneously with 39 parts dimeric toluylene diisocyanate.
The mixture is subsequently activated using 1% activator mixture
as in Example 1.
The paste produced sets within two minutes at 110.degree. C. but
remains flexible and tacky, in contrast to the polyurethane from
Example 1. Although the paste is still of a putty-like consistency
after 24 hours storage at room temperature, curing is even less
complete at 110.degree. C.
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. |