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...
Utility Patent
1999-06-03
2001-01-02
Szekely, Peter A. (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...
C524S270000, C524S272000, C524S273000, C524S274000, C524S915000
Utility Patent
active
06169132
ABSTRACT:
The present invention relates to an aqueous composition comprising
from 10 to 35% by weight of a water-dispersed polymer A) having a glass transition temperature Tg of below −10° C.
from 5 to 22% by weight of a resin B) which is liquid at 23° C. and 1 bar, has a glass transition temperature of below −10° C. and in which abietic acid is soluble at 23° C. and 1 bar such that it is possible to obtain solutions of resin B and abietic acid having a weight content of up to 50% by weight of abietic acid
from 5 to 22% by weight of resin C) which is based in abietic acid or on modified abietic acid and has a glass transition temperature of from 0 to 90° C. and
from 21 to 80% by weight of a filler D),
the percentages by weight being based on the sum of the constituents of the aqueous composition with the exception of water.
The invention additionally relates to the use of said aqueous composition as an adhesive for floor coverings.
Adhesives generally are required to display good adhesion—in other words, to stick well to the substrate—and good cohesion—in other words, to hold together well within the adhesive film. Adhesives for floor coverings are subject to particular requirements. Here, there is a desire in particular for good wet bonding capacity. A good wet bonding capacity means that after a carpet, for example, has been laid on the substrate which is coated with the aqueous dispersion, the carpet can initially still be aligned and its position corrected but that, soon thereafter, a slipproof bond developes whose strength increases as drying progresses.
A good dry gripping capacity means that even after a long period of ventilation a carpet, after having been laid on the substrate, which is then dry, gives a firm, slipproof bond.
A further desired aim is to dispense with volatile organic constituents, such as solvents or plasticizers, in order to avoid subsequent exposure to corresponding emissions.
Flooring adhesives are known already from EP-A-490191 and WO 95/21884 and German Patent Application P 19 801 892.4 (OZ 48 723).
Fundamentally, therefore, there is a desire for adhesives which in the course neither of processing nor of subsequent use emit substances which pollute the air in the room, and which, at the same time, are notable in performance terms for good tackiness, such as good wet bonding and dry gripping capacities, and high thermal stability of the bond.
It is an object of the present invention to provide adhesives, especially flooring adhesives, having the above properties.
We have found that this object is achieved by the aqueous composition defined at the outset and by its use as an adhesive.
The aqueous composition comprises preferably
from 15 to 30% by weight, with particular preference from 18 to 28% by weight, of the polymer A)
from 7 to 19% by weight, with particular preference from 9 to 16% by weight, of the resin B)
from 7 to 19% by weight, with particular preference from 9 to 16% by weight, of the resin C) and
from 32 to 71% by weight, with particular preference 40-64% by weight, of filler D).
These percentages by weight are based on the sum of the components of the aqueous composition with the exception of water, i.e., essentially the solids content of the formulation.
The solids content of the composition of the invention is preferably 65-92%, especially 76-84% by weight.
The polymer A) is preferably a free-radically polymerized polymer composed of ethylenically unsaturated monomers.
The polymer preferably comprises principal monomers selected from C
1
-C
20
-alkyl (meth)acrylates, vinyl esters of carboxylic acids having up to 20 carbons, vinylaromatic compounds having up to 20 carbons, ethylenically unsaturated nitriles, vinyl halides, nonaromatic hydrocarbons having at least 2 conjugated double bonds, or mixtures of these monomers.
The abovementioned monomers and monomer mixtures are preferably present in the polymer to an extent of from 60 to 100% by weight, preferably from 80 to 100% by weight and, with particular preference, from 90 to 99.8% by weight, based on the polymer.
Mention may be made specifically, for example, of C
1
-C
12
-alkyl (meth)acrylates, such as methyl methacrylate, methyl acrylate, n-butyl acrylate, ethyl acrylate and 2-ethylhexyl acrylate.
Mixtures of the (meth)acrylic alkyl esters are also particularly suitable.
Examples of vinyl esters of carboxylic acids having 1 to 20 carbons are vinyl laurate, vinyl stearate, vinyl propionate, vinyl esters of Versatic acid (chemical name: neonanonic acid; formula C
8
H
17
COOH), and vinyl acetate.
Suitable vinylaromatic compounds are vinyltoluene, &agr;- and p-methylstyrene, &agr;-butylstyrene, 4-n-butylstyrene, 4-n-decylstyrene and, preferably, styrene. Examples of nitriles are acrylonitrile and methacrylonitrile.
The vinyl halides are ethylenically unsaturated compounds substituted by chlorine, fluorine or bromine, preferably vinyl chloride and vinylidene chloride.
As nonaromatic hydrocarbons having 2 to 8 carbons and at least two olefinic double bonds there may be mentioned butadiene, isoprene and chloroprene.
Particular preference is given to (meth)acrylic esters and mixtures thereof.
Further monomers, which may be present, for example, to an extent of from 0 to 40% by weight, preferably from 0 to 20% by weight and, with particular preference, from 0.2 to 10% by weight in the polymer, are, in particular, C
1
-C
10
-hydroxyalkyl (meth)acrylates, (meth)acrylamide and its derivatives substituted on the nitrogen by C
1
-C
4
-alkyl, ethylenically unsaturated carboxylic acids, dicarboxylic acids, their monoesters and anhydrides, examples being (meth)acrylic acid, maleic acid, fumaric acid, maleic anhydride, maleic and fumaric monoesters, and itaconic acid. Very particular preference is given to a content of from 0.2 to 5% by weight of an ethylenically unsaturated carboxylic acid.
The glass transition temperature of the polymer lies preferably between −50 and −10°C., in particular between −40 and −15° C. and, with very particular preference, between −15 and −30° C.
The glass transition temperature of the polymer can be determined by customary methods, such as differential thermal analysis or differential scanning calorimetry (see e.g. ASTM 3418/82, midpoint temperature).
The gel content of the polymer A) is preferably below 40% by weight, more preferably below 30% by weight and, with particular preference, below 20% by weight, based on the polymer A). The gel content should preferably be more than 5% by weight.
The gel content is the content of insoluble constituents. It is determined and defined by the following method: The dispersion is dried at 21° C. to give a film approximately 1 mm thick. One gram of the polymer film is added to 100 ml of tetrahydrofuran and is allowed to stand at 21° C. for a week. Thereafter, the resulting solution or mixture is filtered with the aid of a cloth filter (mesh size 125 &mgr;m). The residue (swollen film) is dried at 21° C. for 2 days in a vacuum drying cabinet and then weighed. The gel content is the mass of the weighed residue divided by the mass of the polymer film employed.
The tetrahydrofuran-soluble fractions of the polymer are, correspondingly, preferably from 60 to 100% by weight, more preferably from 70 to 100% by weight and, with particular preference, from 80 to 100% by weight, in particular up to 95% by weight, based on the polymer.
The number-average molecular weight M
n
of these soluble fractions is preferably less than 30,000, in particular less than 20,000 and, more preferably, less than 15,000, and the weight-average molecular weight M
w
is preferably more than 250,000 (as determined by gel permeation chromatography with polystyrene as standard on a polymer solution in tetrahydrofuran following sedimentation of the insoluble constituents).
Generally, however, M
n
is not less than 5000 g/mol and M
w
is not more than 800,000 g/mol.
The polymer is prepared by free-radical polymerization. Suitable methods of polymerization, such as bulk, solution, suspension or emulsion polymerization, are kn
Fickeisen Peter
Wistuba Eckehardt
BASF - Aktiengesellschaft
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Szekely Peter A.
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