Silane-containing polymer dispersions for tile cements

Details Silane-containing polymer dispersions for tile cements Silane-containing polymer dispersions for tile cements

2001-08-13

2003-05-06

Yoon, Tae H. (Department: 1714)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

At least one aryl ring which is part of a fused or bridged...

C524S211000, C524S213000, C524S806000, C524S812000

Reexamination Certificate

active

06559221

ABSTRACT:

DESCRIPTION
The invention relates to an aqueous polymer dispersion, wherein the dispersion contains from 0.0001 to 1 mol of a hydrolyzable silicon group and from 0.0001 to 1 mol of a urea or thiourea group, based, in each case, on 100 g of the polymers present in the dispersion.
The invention also relates to a method of using the polymer dispersions as binding agents for adhesives and sealants, particularly for tile cements.
EP-A 35,332 discloses binding agents for ceramic tiles, which have a content of hydrolyzable silicon groups arising from copolymerization of ethylenically unsaturated silicon compounds. EP-A 366,969 also describes binding agents containing hydrolyzable silicon groups.
The water resistance of adhesive bonds is raised by a content of hydrolyzable silicon compounds.
It is desirable that adhesive bonds should have not only high water resistance but also optimal heat resistance. Prior art binding agents are still unsatisfactory with regard to their heat resistance.
Polymers containing urea groups are disclosed in EP-A 184,091 for example.
Thus the present invention relates to binding agents for adhesives giving water-resistant and heat-resistant adhesive bonds.
Accordingly we have found the polymer dispersion defined above and a method of using the same as a binding agent for adhesives and sealants, particularly for use on ceramic tiles.
The aqueous polymer dispersion of the invention contains at least 0.0001 mol and preferably at least 0.0005 mol of a urea or thiourea group, while the upper limit is not more than 1 mol, preferably not more than 0.5 mol, more preferably not more than 0.1 mol, very preferably not more than 0.05 mol and most preferably not more than 0.01 mol, based, in each case, on 100 g of the polymers dispersed in the dispersion.
In particular, the group under consideration is a urea or thiourea group of the formula
in which R
1
and R
2
independently stand for a hydrogen atom or a C
1
-C
5
alkyl group or R
1
and R
2
together stand for a bridging C
1
-C
4
alkylene group, which can be mono- or di-substituted by a C
1
-C
4
alkoxy group or a hydroxyl group, and X stands for an oxygen or sulfur atom.
Preferably R
1
and R
2
independently stand for hydrogen or a C
1
-C
5
alkyl group or R
1
and R
2
together stand for a bridging C
2
-C
4
alkyl group. X preferably stands for 0.
In a particularly preferred embodiment, R
1
and R
2
together stand for a C
2
-C
4
alkylene group, particularly an ethylene group, connecting the two nitrogens.
The urea or thiourea group can be a component of a low-molecular, non-polymeric compound dissolved or dispersed in water as continuous phase.
In particular, such compounds have at least 2 and preferably 2-4 urea or thiourea groups.
Preferably the urea or thiourea group is bonded to the polymers dispersed in the dispersion.
These polymers can be polycondensates, eg polyesters, or addition polymers, eg polyurethanes.
Preferably they are polymers which can be obtained by free-radical or ionic polymerization of ethylenically unsaturated compounds (monomers) (ie radical-polymerized polymers).
The urea or thiourea group can be bonded to the polymer by, say, polymer-analogous conversion.
Preferably synthesis of the polymers is carried out in the presence of suitable starting compounds already containing a urea or thiourea group. In the preferred embodiment involving radical-polymerized polymers, polymerization is preferably carried out using monomers containing a urea or thiourea group (monomer A).
Such monomers have, in addition to the urea or thiourea group, at least one, preferably one, copolymerizable ethylenically unsaturated group.
This copolymerizable, ethylenically unsaturated group in monomer A is preferably a (meth)acrylic group.
Suitable monomers A preferably contain one copolymerizable, ethylenically unsaturated group and one group of formula I.
Preferably the compound used is one of the formula
in which R
3
stands for a hydrogen atom or a methyl group, Y for —O— or —NH— and R
4
for a divalent C
1
-C
10
alkylene group, and R
1
, R
2
have the meanings stated above.
Preferably R
3
stands for hydrogen or a methyl group, Y for —O—, R
4
for a C
2
-C
6
alkylene group and R
1
and R
2
together stand for a C
2
-C
4
alkylene group.
Particular preference is given to 1-(2-methacryloxyethyl)imidazolinone-2, known as ureidoethylene methacrylate (R
1
, R
2
=ethylene; Y=O; R
3
=methyl; R
4
=ethylene; abbreviation=UMA):
or ureidoethylene acrylate.
The aqueous polymer dispersion of the invention also contains a hydrolyzable silicon group, ie a silicon group which, following hydrolysis, has at least one hydroxyl group directly attached to the Si atom.
In particular, it is a silicon group of the formula
in which R
5
to R
7
each independently stand for a C
1
-C
8
, in particular C
1
-C
4
, alkyl or alkoxy group, provided that at least one of the radicals R
5
to R
7
denotes an alkoxy group.
In a particularly preferred embodiment, all radicals R
5
-R
7
stand for a C
1
-C
8
, preferably C
1
-C
4
, alkoxy group, in particular a methoxy group.
The content of hydrolyzable silicon group in the aqueous polymer dispersion is from 0.0001 to 1 mol. Preferably the content is at least 0.0005 mol, while the upper limit is not more than 1 mol, preferably not more than 0.5 mol, more preferably not more than 0.1 mol, very preferably not more than 0.05 mol and most preferably not more than 0.01 mol, based, in each case, on 100 g of the polymers dispersed in the dispersion.
The molar ratio of the urea or thiourea group to the silicon group is preferably from 1:10 to 10:1 and more preferably from 1:5 to 5:1.
The hydrolyzable silicon group may also be a component of a low-molecular, non-polymeric compound dissolved or dispersed in the dispersant water.
In particular, such compounds have at least 2, preferably from 2 to 4, hydrolyzable silicon groups. If these compounds have only one hydrolyzable silicon group, this silicon group preferably has at least two hydrolyzable groups however.
Preferably the hydrolyzable silicon group is bonded to the polymer. Very preferably, both the urea or thiourea group and the hydrolyzable silicon group are bonded to the polymer.
In the preferred embodiment involving radical-polymerized polymer, monomers containing a hydrolyzable silicon group can be used, for example, as comonomers in the polymer dispersion (monomer B). Also suitable are polymerization regulators containing, for example, one —S—H group and one hydrolyzable silicon group (regulators B).
Such regulators B are attached to the ends of the polymer chains during free-radical polymerization.
Suitable monomers B are eg those of the formula
in which Z stands for a
vinyl group (H
2
C═CH—),
acrylic group
or
methacrylic group
Y stands for a binding link containing up to 20 carbons, whilst Y may be omitted if Z stands for a vinyl group, and
R
5
to R
7
have the meanings stated above.
Preferably Z stands for a (meth)acrylic group and Y for a C
1
-C
6
alkylene group.
Suitable regulators B are eg those of the formula
in which R
8
and R
9
independently stand for a hydrogen atom or a C
1
-C
4
alkyl group, n is a number from 0 to 10, preferably from 1 to 8, and R
5
-R
7
have the meanings stated above.
The polymers dispersed in the polymer dispersion of the invention are preferably radical-polymerized polymers.
Preferably the radical-polymerized polymer comprises so-called main monomers to an extent of at least 40 wt % and more preferably at least 60 wt % and most preferably at least 80 wt %.
The main monomers are selected from the group comprising C
1
-C
20
alkyl (meth)acrylates, vinyl esters of carboxylic acids containing up to 20 carbons, vinyl aromatic compounds containing up to 20 carbons, ethylenically unsaturated nitriles, vinyl halides, vinyl ethers of alcohols containing from 1 to 10 carbons, aliphatic hydrocarbons containing from 2 to 8 carbons and having 1 or 2 double bonds, or mixtures of these monomers.
The following may be mentioned by way of example: alkyl (meth)acrylates containi

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