Note: Descriptions are shown in the official language in which they were submitted.
~7~374
Heat-sensitive latex mixtures are known which are
produced from heat-sensitisable polymer latices which in turn
may be produced by emulsion polymerisation. Their heat
sensitisation characteristics and agents suitable for this
purpose are described, for example, in German Patents Nos.
1,268,828; 1,494,037 and in US Patent No. 3,484,394. One
process for the production of heat-sensitisable, synthetic
rubber latices is described in German Patent No. 1,243,394.
Heat-sensitised latex mixtures can be used for impregnating
non-wovens and for the production of hollow bodies (for example
gloves) by the immersion process.
However, conventional heat-sensitised latex mixtures
are not sufficiently stable during processing. In many cases,
the mechanical stability of the heat-sensitised latices is
inadequate so that undesirable deposits are formed on guide
rollers or between squeezing rollers during processing.
In general, non-ionic emulsifiers are added to the latex
mixtures in order to improve their mechanical stability, but
in order to obtain adequate stabilities, considerable quantities
have to be added. This generally has an adverse effect upon
heat sensitisability, in other words relatively large quantities
of heat stabilisers are required for adjusting a predetermined
coagulation temperature.
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The present invention is based on the discovery that
heat-sensitised latex mixtures achieve better mechanical
stability when they contain certain polyethers. Accordingly,
the present invention provides a heat-sensitised synthetic
polymer latex obtained by the emulsion polymerisation of one
or more olefinically unsaturated monomers and containing from
0.05 to 10% by weight, based on the polymer, of a heat sen-
sitiser, characterised in that said latex also contains a
stabiliser in an amount of from 0.05 to 10% by weight, based
on the polymer, said stabiliser being a polyether or a mix-
ture of polyethers corresponding to the general formula (I):
R [ - (0-CH-CH)x-(O-CH2-CH)y~O~R4]n (I)
Rl R2 R3
in which
R represents optionally aryl-substituted alkyl or cyclo-
alkyl radicals;
Rl, R2 and R3 independently of one another represent hydrogen,
methyl, chloromethyl, ethyl or phenyl, with the proviso that Rl,
R2 and R3 cannot all simultaneously represent hydrogen and, where
_ = 0, Rl and R2 cannot simultaneously represent hydrogen;
R4 represents hydrogen or an aliphatic, cycloaliphatic or
aromatic acyl radical containing from 1 to 30 carbon atoms;
x is an integer from 5 to 100;
_ is 0 or an integer from 1 to 50; and
_ is an integer from 1 to 10.
7874
In preferred polyethers or polyether mixtures,
R represents an alkyl or cycloalkyl radical containing from
2 to 10 carbon atoms;
Rl ~nd R3 represent hydrogen;
R2 represents methyl;
R4 represents hydrogen or an aliphatic acyl radical with
10 to 22 carbon atoms;
x is an integer from 10 to 50;
y is 0 or an integer from 1 to 25; and
10 n is an integer from 1 to 6.
Compounds in which y assumes values of 0 to 10 are
particularly preferred.
The radical R4 may represent either hydrogen or an
acyl radical, both alternatives having significance.
The polvethers which are used as stabilisers in
accordance with the invention are produced by polyalkoxylating
monohydric or polyhydric alcohols and optionally esterifying
the products formed either completely or in part with carboxylic
acids in known manner.
Monohydric or polyhydric alcohols suitable for use in the
synthesis of the polyethers according to the invention are
saturated or unsaturated aliphatic or cycloaliphatic mono-
hydroxy compounds, for example methanol, ethanol, propanol,
isopropanol, butanols, amyl alcohols, hexanols, octanols,
dodecanols, stearyl alcohol, allyl alcohol, oleyl alcohol,
cyclohexanol and benzyl alcohol, polyhydric alcohols, for
example, hexitols, such as sorbitol or mannitol, but preferably
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ethylene glycol, propylene glycol, butane diols, neopentyl
glycol, 2-ethyl-1,3-propane diol and other hexane diols,
1,4-dihydroxymethyl cyclohexane, perhydrobisphenol-A, 2,2~-
bis-[4-(2-hydroxyethyl)-phenyl]-propane, 2,2'-bis-[4-(2-
hydroxypropoxy)-phenyl]-propane and, with particular preference,
trimethylol ethane, trimethylol propane, glycerol and
pentaerythritol.
For producing the polyethers according to the invention,
the monohydric or polyhydric aclohols are polyalkoxylated with
an alkylene oxide or, in stages, with two different alkylene
oxides. Alkylene oxides suitable for use in cases where
alkoxylation is carried out in a single stage are propylene
oxide, 1,2- and 2,3-epoxy butane, isobutylene oxide, 2,3-epoxy
pentane, epichlorhydrin and styrene oxide. Where alkoxylation
is carried out in two stages, the above-mentioned alkylene
oxides are suitable for use in the first stage, whilst
ethylene oxide or propylene oxide in particular is used in
the second stage. Where alkoxylation is carried out in a single
stage, the alcohols are preferably alkoxylated with propylene
oxide, whereas in the two-stage process, the alcohols are
preferably reacted first with propylene oxide and then with
ethylene oxide. It is, of course, also possible to carry out
the reaction first with ethylene oxide and then with propylene
oxide.
In addition to the block polymers, it is also possible to
use copolymeric polyethers for stabilisationS for example
products produced by alkoxylating the alcohols with a mixture
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of propylene and ethylene oxide containing up to 20 mole %
of ethylene oxide, or products which, in a first alkoxylation
stage, contain up to 20 mole /0 of ethylene oxide in addition
to propylene oxide and, in a second stage, up to 20 mole /0
of propylene oxide in addition to ethylene oxide. Although
these products are suitable for stabilisation in accordance
with the invention, they are not preferred.
The alkoxylated alcohols may be used either as such or
may be completely or partly esterified with carboxylic acid.
Suitable carboxylic acids for esterification are aliphatic
and aromatic carboxylic acids containing from 1 to 30 carbon
atoms, but preferably saturated or unsaturated aliphatic
carboxylic acids containing from 10 to 22 carbon atoms, for
example capric acid, lauric acid, palmitic acid, stearic acid,
behenic acid, ricinoleic acid, ricinene acid, linoleic acid,
linolenic acid or abietic acid or mixtures of saturated and/or
unsaturated aliphatic carboxylic acids of the type which
accumulate during the oxidation of paraffins and during the
synthesis of oxo compounds and which are obtained by the
hydrolysis of vegetable or animal fats.
In many cases, the polyethers are only sparingly soluble
in water, if at all, and frequently are also only sparingly
emulsifiable therein. By contrast, their activity increases
with good distribution. Accordingly, in order to improve
their emulsifiability, it is often advisable to add to the
polyethers conventional anion-active or non-ionic emulsifiers,
for example, alkylaryl sulphonates, alkyl sulphates, fatty acid
Le A 17 819 - 6 -
8~4
salts, fatty acid ethoxylates, alkyl phenol ethoxylates, aryl
phenol ethoxylates, aryl phenyl ethoxylates, fatty acid
ethoxylates or the like. Additions of from 1 to 30%~ based
on the polyethers, are generally sufficient.
Heat-sensitised latex mixtures which contain the poly-
ethers defined above are characterised by their high mechanical
stability. In many cases, their stability can be further
increased by adding ammonia in quantities of from 0.1 to 1 /0
by weight, based on polymer. When the heat sensitiser is
added, no undesirable deposits of coagulate are formed.
In all conventional heat-sensitised latices, the improvement
in stability can be obtained by adding the polyether stabilisers
on completion of polymerisation. Examples of the production
of heat-sensitisable latices such as these may be found in
German Patent No. 1,243,394 and in German Offenlegungsschri~ts
Nos. 2,232,526 and 2,005,974. However, stable latex emulsions
are also obtained when the polyethers are added right at the
beginning of or during polymerisation of the latex.
In order to produce the heat-sensitisable stable latices
themselves, conventional olefinically unsaturated monomers may
be polymerised in aqueous emulsion. Suitable monomers include
any radically polymerisable olefinically unsaturated compounds,
for example ethylene, butadiene, isoprene, acrylonitrile,
styrene, divinyl benzene, a-methyl styrene, methacrylonitrile,
acrylic acid, methacrylic acid, 2-chloro-1,3-butadiene,
esters of acrylic acid and methacrylic acid with Cl-C8-alcohols
or polyols, acrylamide, methacrylamide, N-methyloltmeth)
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7874
acrylamide, acrylamido- and methacrylamide-N-methylol
methyl ethers, itaconic acid, maleic acid, fumaric acid,
diesters and semiesters of unsaturated dicarboxylic acids,
vinyl chloride, vinylacetate, vinylidene chloride, which may
be used either individually or in combination with one another.
The polymerisation reaction is carried out in the presence
of emulsifiers, for which purpose the usual non-ionic or anionic
emulsifiers may be used either individually or in combination
with one another. The total quantity of emulsifier amounts to
between 0.1 and 10 /0 by weight, based on the monomers.
Where the polyethers are added during the actual polymerisation
reaction, they are advantageously used in combination with
standard commercial-grade emulsifiers, for example in combination
with alkali sulphonates or sulphates of C12-C18-hydrocarbons
or of alkylated aromatic compounds, or with non-ionic surfactants
or with salts of fatty acids or resinic acids or with salts of
alkyl esters of sulphosuccinic acid.
The quantity of polyether stabiliser added amounts to between
0.05 and 10 /0 by weight, based on monomers, where it is added
to the latex during the actual polymerisation reaction, or to
between 0.05 and 10 /0 by weight, based on polymer, where it is
added to the latex on completion of polymerisation.
The emulsion polymerisation reaction may be initiated
with radical formers, preferably with organoperoxide compounds,
which are used in quantities of from 0.01 to 2 % by weight, based
on monomers. Depending upon the monomer combination, small
quantities of regulators, for example mercaptans, halogenated
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11C~7874
hydrocarbons, may also be used in order to reduce the molecular
weight of the polymer. The emulsion polymerisation reaction
may be carried out in two ways: the entire quantity of monomers
and most of the aqueous phase containing the emulsifiers may
be initially introduced, the polymerisation reaction initiated
by adding the initiator and the rest of the aqueous phase added
either continuously or in portions during the polymerisation
reaction. The "monomer input" technique may also be used.
In this case, only part of the monomers and the aqueous phase
containing the emulsifier is initially introduced and the
rest of the monomers and aqueous phase added either continuously
or in portions, according to the conversion, after the
polymerisation reaction has been initiated. The proportion
of monomer subsequently added may be pre-emulsified in the
aqueous phase. Both processes are known.
Additives may be introduced into the heat-sensitisable
latices before or during processing. Thus, acid donors which
are added in addition to the sensitiser promote coagulatability
by reducing the coagulation temperature. Examples of other
suitable additives are dyes, pigments, fillers, thickeners,
electrolytes, antiagers, water-soluble resins or vulcanisation
chemicals.
After their production, the heat-sensitisable latices are
heat-sensitised by the addition of heat sensitisers in
quantities of from 0.05 to 10 ~ by weight, based on the polymer.
In this connection, it has been found that latices containing
the polyether stabilisers according to the invention are
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7~4
particularly stable so that when heat sensitisers are added
to these latices no ¢oagulation occurs. Suitable heat
sensitisers are inter alia organopolysiloxanes, for example
according to German Auslegeschrift No. 1,268,828; German
Offenlegungsschrift No. 1,494,037 and US Patent Specification
No. 3,484,394. Other suitable heat sensitisers are polyvinyl
methyl ethers, polyglycol ethers, polyether thioethers,
polyol-N-vinyl caprolactam and/or polycarboxylic acids.
The heat-sensitised latex mixtures according to the
invention may be used, for example, for bonding non-wovens
consisting of synthetic or natural fibres. Examples
are non-wovens of cotton , rayon staple, wool, polyamides,
polyesters, polyacrylonitrile, glass fibres, mineral wool,
asbestos wool or metal filaments.
EXAMPLE 1
The following stabilisers are mentioned as examples:
A) The polyether produced by alkoxylating trimethylol propane
first with 41 moles of propylene oxide and then with
10 moles of ethylene oxide, OH-number: 57.
B) Oleic acid ester of polyether A
To produce this product, 500 g of polyether A are esterified
with 94 g of oleic acid (acid number 203) at a temperature
of 180 to 190C. Approximate~ 9 ml of water are distilled
off over a period of 16 hours (acid number of the ester
15.4).
C) The polyether produced by alkoxylating trimethylol propane
initially with 84 moles of propylene oxide and subsequently
with 23 moles of ethylene oxide, OH-number 28.
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D) The polyether produced by alkoxylating trimethylol propane
initially with 70 moles of propylene oxide and subsequently
with 14 moles of ethylene oxide, OH-number 35.
E) The polyether produced by alkoxylating pentaerythritol
initially with 84 moles of propylene oxide and subsequently
with 20 moles of butylene oxide, OH-number 37.5.
F) Polypropylene glycol produced from 1 mole of propylene
glycol and 33 moles of propylene oxide, OH-number 58.3.
G) The polyether produced by propoxylating trimethylol
propane with 50 moles of propylene oxide, OH-number 58.2.
H) Peanut oil fatty acid ester of polyether E:
To produce this product, 498 g of polyether E are
esterified with 88 g of peanut oil fatty acid (acid number
203) at a temperature of 180 - 190C. Approximately 6 ml
of water are distilled off over a period of 14 hours
(acid number of the ester 17.2).
I) Soya oil fatty acid of polyether C:
To produce this product, 500 g of polyether C are esterified
with 61.7 g of soya oil fatty acid (acid number 215.5)
at a temperature of 180 to 190C. Approximately 4.5 ml of
water are distilled off over a period of 20 hours (acid
number of the ester 15.1).
K) Polypropylene glycol produced by propoxylating propylene
oxide with 23 moles of propylene oxide, OH-number 78.2.
L) The polyether produced by propoxylating methanol with 17
moles of propylene oxide, OH-number: 57.1.
M) The polyether produced by alkoxylating sorbitol first with -
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ii78~4
170 moles of propylene oxide and then with 45 moles of
ethylene oxide, OH-numbe:r 28.
EXAMPLE 2
2L0 parts by weight of a 47 % latex of the copolymer of
5 62~o by weight of butadiene, 34.0 % by weight of acrylonitrile
and 4.0 % by weight of methacrylic acid,
27.5 parts by weight of a vulcanisation paste consisting of
0.5 % by weight of colloidal sulphur, 0.5 % by weight of zinc-
N,N'-diethyl dithiocarbamate, 3.75 % by weight of zinc
mercaptobenzthiazole, 12.5 % by weight of zinc oxide, 12.5 %
by weight of titanium di.oxide and 70.25 % by weight of a 5 %
aqueous solution of a condensation product of naphthalene
sulphonic acid with formaldehyde,
2.5 parts by weight of a 25 % ammonia solution,
15 130 parts by weight of water,
1 part by weight of organopolysiloxane (Coagulant WSR, a
product of Bayer AG) and
1 part by weight of a stabiliser according to Example 1, were
stirred together. The coagulation point of the mixture was
20 determined immediately, 1 hour, 2 hours, 1 day and 7 days after
production.
The coagulation point of the latex mixture was determined
as follows:
Approximately 10 g of the heat-sensitised mixture were
25 weighed into a glass beaker which was then introduced into a
water bath having a constant temperature of 80C. The coagulation
behaviour and increase in temperature were followed while the
mixture was uniformly stirred with a thermometer. The
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374
coagulation point of the mixture was the temperature at which
a complete and final separation of polymer and aqueous phase
occurred.
Table
Stabiliser Coa~ulation temperature (C ) after:
immediately lh 2h 1 day 7 days
A 41 41 42 42 43
B 41 41 41 42 42
C 43 42 42 43 45
D 44 46 46 46 47
E 48 50 50 5 51
F 42 40 40 39 39
G 44 46 46 45 45
H 54 55 53 53 53
I ~9 40 40 40 41
K 37 37 38 37 36
L 37 39 39 37 37
M 38 41 41 41 41
_
EXAMPLE 3
This Example demonstrates the dependence of the coagulation
temperature upon the quantity of stabiliser used. Mixtures were
produced in accordance with Example 2, stabiliser A being used
in other quantities in addition to 1 part by weight.
Table
Quantity of Coa~ulation t _ ,ure (~ ') aiter
stabiliser immediately ~ ~ j 1 day j 7 days
25 oo 5 37 3378 378 388 40
1 0 41 43 42 42 43
2 0 55 55 56 58 59
2.5 72 73 73 75 77
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EXAMPLE 4
Mixtures were produced in accordance with Example 2. In
contrast to Example 2, however, 2 parts by weight of organo-
polysiloxane (Coagulant WS) and different quantities by weight
5 of stabiliser A were used.
Table
Quantity of Coa~ulation temperature (C) after
stabiliser = lh 2h ~ l I~YL~
0.5 34 33 34 35 33
l . o 36 37 37 39 38
2.0 40 40 40 41 43
3.0 43 43 44 46 45
4.0 48 48 49 49 5
EXAMPLE 5
This Examples also demonstrates the dependence oi the
coagulation temperature upon the quantity of stabiliser used.
250.0 parts by weight of a 40 ~ latex of the copolymer of
60.0 % by weight of butadiene, 34.0 ~ by weight of acrylonitrile,
2.0 /0 by weight of acrylic acid, 2.0 ~ by weight of methacrylamide
and 2.0 % by weight of methacrylamido-N-methylol methyl ether,
x parts by weight of stabiliser A (see Example 1), 38.0 parts
by weight of water and 2.0 parts by weight of organopolysiloxane
(Coagulant WSR , a product of Bayer AG) were combined.
The coagulation points of the mixtures were determined
immediately, 30 minutes, 1 day and 6 days after production.
The coagulation points were measured by the method described
in Example 2.
Le A 17 819 - 14 -
11(:17~74
Table
: Quantity of Coa~ulation t emperature ( ,) after
stabiliser immediately 30 mins. 1 da~ 7 days
A used (g)
: 5 5 43 44 45 47
- 1 0 52 54 54 58
1 5 61 61 64 64
:~ 2.0 68 68 7 7
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Le A 17 819 - 15 -
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