Heat curable binders

Details Heat curable binders Heat curable binders

2002-04-18

2004-05-04

Cheung, William (Department: 1713)

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...

C524S730000, C524S602000, C524S607000, C524S766000, C524S796000, C106S644000, C106S711000, C106S797000

Reexamination Certificate

active

06730729

ABSTRACT:

The invention relates to a process for preparing an aqueous polymer dispersion comprising
an emulsion polymer (EP for short)
a polymer composed of at least 5% by weight of an ethylenically unsaturated monocarboxylic acid, dicarboxylic acid or dicarboxylic anhydride (acid polymer SP for short), and
an alkoxysilane of the formula
SiR
1
R
2
R
3
R
4
in which the groups R
1
to R
4
independently of one another are each an organic radical with the proviso that at least one of the groups is an alkoxy group, which comprises preparing said emulsion polymer by emulsion polymerization in the presence of at least some of the alkoxysilane.
The invention further relates to aqueous polymer dispersions obtainable by the process and the use of said dispersions as binders.
Heat curable binders made from polycarboxylic acids and polyols and/or alkanolamines are known, for example, from EP-A-445578, EP-A-583086, EP-A-882074, EP-A-882093 or DE-A-19949592 (OZ 50804).
In EP-A-882074 and DE-A-19949592, alkoxysilanes are among the possible additives mentioned for such binders.
It is an object of the present invention to improve further the performance properties of heat curable binders, and especially the strength of the moldings produced, as compared with their prior art counterparts. The binders ought at the same time to be obtainable by means of an extremely simple process.
We have found that this object is achieved by the above process and, respectively, by the binders obtainable by the process, and their use.
The emulsion polymer (EP) consists of at least 40% by weight, with particular preference at least 60% by weight, with very particular preference at least 80% by weight, of what are known as principal monomers.
The principal monomers are selected from C
1
-C
20
alkyl (meth)acrylates, vinyl esters of carboxylic acids containing up to 20 carbon atoms, vinylaromatics having up to 20 carbon atoms, ethylenically unsaturated nitrites, vinyl halides, vinyl ethers of vinyl alcohols containing 1 to 10 carbon atoms, aliphatic hydrocarbons having from 2 to 8 carbon atoms and 1 or 2 double bonds, and mixtures of these monomers.
Examples include (meth)acrylic acid alkyl esters having a C
1
-C
10
alkyl radical, such as methyl methacrylate, methyl acrylate, n-butyl acrylate, ethyl acrylate and 2-ethylhexyl acrylate.
Also suitable in particular are mixtures of the alkyl (meth)acrylates.
Examples of vinyl esters of carboxylic acids having from 1 to 20 carbon atoms are vinyl laurate, vinyl stearate, vinyl propionate, Versatic acid vinyl esters, and vinyl acetate.
Suitable vinylaromatic compounds include vinyltoluene, &agr;- and p-methylstyrene, &agr;-butylstyrene, 4-n-butylstyrene, 4-n-decylstyrene and—preferably—styrene. Examples of nitrites are acrylonitrile and methacrylonitrile.
The vinyl halides are chloro-, fluoro- or bromo-substituted ethylenically unsaturated compounds, preferably vinyl chloride and vinylidene chloride.
Examples of vinyl ethers include vinyl methyl ether and vinyl isobutyl ether. Vinyl ethers of alcohols containing from 1 to 4 carbon atoms are preferred.
Hydrocarbons that may be mentioned, having from 2 to 8 carbon atoms and two olefinic double bonds, include butadiene, isoprene and chloroprene; those with one double bond include, for example, ethylene and propylene.
Preferred principal monomers are the C
1
to C
10
alkyl acrylates and methacrylates, especially C
1
to C
8
alkyl acrylates and methacrylates. Suitable compounds preferably also include mixtures of C
1
-C
10
alkyl acrylates or C
1
-C
10
alkyl methacrylates with vinylaromatics, especially styrene.
Very particular preference is given to methyl acrylate, methyl methacrylate, ethyl acrylate, n-butyl acrylate, n-hexyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, styrene, and mixtures of these monomers.
Besides the principal monomers, the free-radically polymerized polymer may contain further monomers, e.g., monomers having carboxylic acid, sulfonic acid or phosphonic acid groups. Carboxylic acid groups are preferred. Examples that may be mentioned include acrylic acid, methacrylic acid, itaconic acid, maleic acid, and fumaric acid.
Examples of further monomers include hydroxyl-containing monomers, especially C
1
-C
10
hydroxyalkyl (meth)acrylates, and (meth)acrylamide.
Further monomers that may be mentioned also include phenyloxyethyl glycol mono(meth)acrylate, glycidyl acrylate, glycidyl methacrylate, and amino (meth)acrylates such as 2-aminoethyl (meth)acrylate.
As further monomers, mention may also be made of crosslinking monomers.
Mention may also be made, further, of monomers containing hydrolyzable Si groups.
The fraction of monomers containing carboxylic acid groups or carboxylic anhydride groups is generally below 5% by weight, in particular below 3% by weight, based on EP.
EP is prepared by emulsion polymerization.
The emulsion polymerization is carried out using ionic and/or nonionic emulsifiers and/or protective colloids and/or stabilizers as surface-active compounds.
A detailed description of suitable protective colloids is given in Houben-Weyl, Methoden der organischen Chemie, volume XIV/1, Makromolekulare Stoffe, Georg-Thieme-Verlag, Stuttgart, 1961, pp. 411 to 420. Suitable emulsifiers include anionic, cationic, and nonionic emulsifiers. As accompanying surface-active substances it is preferred to use exclusively emulsifiers, whose molecular weights, unlike those of the protective colloids, are usually below 2000 g/mol. Where mixtures of surface-active substances are used, the individual components must of course be compatible with one another, something which can be checked in case of doubt by means of a few preliminary tests. It is preferred to use anionic and nonionic emulsifiers as surface-active substances. Examples of customary accompanying emulsifiers are ethoxylated fatty alcohols (EO units: 3 to 50, alkyl: C
8
to C
36
), ethoxylated mono-, di- and tri-alkylphenols (EO units: 3 to 50, alkyl: C
4
to C
9
), alkali metal salts of dialkyl ester of sulfosuccinic acid and also alkali metal salts and ammonium salts of alkyl sulfates (alkyl: C
8
to C
12
), of ethoxylated alkanols (EO units: 4 to 30, alkyl: C
12
to C
18
), of ethoxylated alkylphenols (EO units: 3 to 50, alkyl: C
4
to C
9
), of alkylsulfonic acids (alkyl: C
12
to C
18
), and of alkylarylsulfonic acids (alkyl: C
9
to C
18
).
Further suitable emulsifiers are compounds of the formula II
in which R
5
and R
6
are hydrogen or C
4
to C
14
alkyl but are not simultaneously hydrogen and X and Y may be alkali metal ions and/or ammonium ions. Preferably, R
5
and R
6
are linear or branched alkyl radicals having from 6 to 18 carbon atoms or hydrogen and in particular have 6, 12 or 16 carbon atoms, R
5
and R
6
not both simultaneously being hydrogen. X and Y are preferably sodium, potassium or ammonium ions, particular preference being given to sodium. Particularly advantageous compounds II are those in which X and Y are sodium, R
5
is a branched alkyl radical having 12 carbon atoms, and R
6
is hydrogen or R
5
. Use is frequently made of technical-grade mixtures containing a fraction of from 50 to 90% by weight of the monoalkylated product, an example being Dowfax® 2A1 (trademark of Dow Chemical Company).
Suitable emulsifiers can also be found in Houben-Weyl, Methoden der organischen Chemie, volume 14/1, Makromolekulare Stoffe, Georg Thieme Verlag, Stuttgart, 1961, pages 192 to 208.
Examples of emulsifier trade names are Dowfax® 2A1, Emulan® NP 50, Dextrol® OC 50, Emulgator 825, Emulgator 825 S, Emulan® OG, Texapon® NSO, Nekanil® 904 S, Lumiten® I-RA, Lumiten E 3065, Disponil FES 77, Lutensol AT 18, Steinapol VSL and Emulphor NPS 25.
The surface-active substance is normally used in amounts of from 0.1 to 10% weight, based on the monomers to be polymerized.
Examples of water-soluble initiators for the emulsion polymerization are ammonium salts and alkali metal salts of peroxodisulfuric acid, e.g., sodium peroxodisulfate, hydrogen peroxide or organic peroxides, e.g., tert-butyl hydroperoxide.
Initiator systems known as reduction-oxidat

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