Aqueous dispersions, process for the production thereof and use thereof

Aqueous dispersions comprising emulsified polyolefins and metal salts of phosphoric acid esters which are useful for sizing glass fibers.

BACKGROUND OF THE INVENTION 
The present invention relates to aqueous dispersions containing modified 
polyolefin as their principal constituents, to a process for the 
production thereof and to the use thereof for the surface modification of 
solids, in particular for sizing glass fibers. 
It is known that the properties of composites made from glass fibers and 
polymers are to a great extent influenced by the shear strength between 
the glass fibers and the polymers surrounding the glass fibers, the 
so-called matrix polymers. The task of the glass fiber size is to create 
this adhesion between the glass fibers and the matrix polymer, and 
moreover to ensure the production and processing properties of the glass 
fibers. The sizes used are compositions prepared from water, polymeric 
binders (so-called film formers), coupling agents, lubricants, anti-static 
agents and further auxiliary substances, wherein the formulations of the 
sizes must be optimized for the particular polymer matrix. Generally, the 
binders used are organic, water-dispersible or soluble polyvinyl acetate, 
polyester, polyester epoxide, polyurethane, polyacrylate, polyolefin 
resins or mixtures thereof. 
It is in principle highly problematic to reinforce polyolefins with glass 
fibers due to the chemical inertness and low polarity of polyolefins. 
Glass fibers have relatively high surface polarity and are thus largely 
incompatible with polyolefins. Consequently, polyolefin dispersions (BE 
750 649, BE 807 979 and U.S. Pat. No. 3,480,580) are virtually exclusively 
used as the film formers for glass fibers suitable for polyolefins. Other 
film formers, for example containing polyurethane, vinyl acetate or 
epoxide are, in contrast, incompatible with polyolefins and are unsuitable 
as they prevent any bond between the fiber and matrix. In these cases, the 
composites produced from glass fibers and polyolefins exhibit deficient 
mechanical properties, such as, for example, tensile and flexural strength 
or impact strength. 
There is, however, demand from the market for glass fibers which are also 
suitable for reinforcing polyolefins and which, in comparison with the 
prior art, offer improved properties, in particular improved tensile and 
flexural strength, of the polyolefin matrix. 
The object of the invention is thus to provide a dispersion which is 
suitable for coating the surface of solids, in particular for sizing glass 
fibers, which dispersion increases compatibility between the surface of 
the solid and the matrix olefin and so improves adhesive properties. 
SUMMARY OF THE INVENTION 
It surprisingly proved possible to achieve this object with an aqueous 
dispersion containing an emulsified polyolefin and metal salts of a 
phosphorus ester. This was all the more surprising, as it had hitherto 
only been known to add metal salts of phosphoric acid esters to 
polyolefins in order to improve their optical properties, in particular as 
films (T. Haruna, E. Tobita, Annu. Tech., (1992), pages 2029-2034). The 
aqueous dispersions according to the invention improve the adhesive 
properties between the polyolefin and a correspondingly treated solid as 
well as their compatibility Conf. Soc. Plast. Eng. Thus, for example, 
polyolefins reinforced with glass fibers exhibit considerably better 
properties if the glass fibers have been treated with a size containing 
the aqueous dispersion according to the invention. 
DESCRIPTION 
The present invention provides aqueous dispersions consisting essentially 
of about 
a) 40 to 95 wt. % of water, 
b) 4 to 60 wt. % of emulsified polyolefin prepared from 
b1) 60 to 95 wt. %, relative to (b), of polyolefin modified with acid 
groups 
b2) 10 to 40 wt. %, relative to (b), of emulsifier and 
b3) 1 to 7 wt. %, relative to (b), of base, 
c) 0.1 to 15 wt. % of metal salts of phosphoric acid esters of the general 
formula (I) 
##STR1## 
wherein 
A.sup.1 and A.sup.2 each independently is a monofunctional hydrocarbon 
radical with 8 to 40 carbon atoms, or together are a difunctional 
hydrocarbon radical with 16 to 80 carbon atoms, 
a is a number from 1 to 3 and 
M is an a-valent metal ion and 
d) 0 to 10 wt. % of further additives and auxiliary substances. 
The present invention also provides a process for the production of the 
aqueous dispersions according to the invention, which process is 
characterized in that 
a) 40 to 95 wt. % of water, 
b) 4 to 60 wt. % of emulsified polyolefin prepared from 
b1) 60 to 95 wt. %, relative to (b), of polyolefin modified with acid 
groups 
b2) 10 to 40 wt. %, relative to (b), of emulsifier and 
b3) 1 to 7 wt. %, relative to (b), of base, 
c) 0.1 to 15 wt. % of metal salts of phosphoric acid esters of the general 
formula (I) 
##STR2## 
wherein A.sup.1, A.sup.2 a and M have the above-stated meanings and 
d) 0 to 10 wt. % of further additives and auxiliary substances are combined 
and then heated to temperatures of between 60.degree. and 200.degree. C., 
preferably between 90 and 190.degree. C., and are subsequently cooled. 
Components a), b1) to b3), c) and optionally d) are combined, then heated 
and recooled, wherein a finely divided, aqueous dispersion is obtained. 
Since the metal salts of the phosphoric acid esters of the formula (I) are 
soluble only in moderately polar solvents and are insoluble in 
polyolefins, it was not to be expected that the combination of these metal 
salts with the emulsifiable polyolefins would yield an aqueous dispersion. 
The dispersions according to the invention are used for the surface 
modification of solids, in particular as a size component for sizing glass 
fibers. They are preferably used in sizes which, before application onto 
the glass fibers, contain 
1) 2 to 20 wt. %, preferably 4 to 10 wt. %, of solids of the aqueous 
dispersion according to the invention, 
2) 0 to 20 wt. %, preferably 0 to 10 wt. %, of solids of polyolefin, 
polyepoxide, polyester, polyvinyl acetate or polyurethane film formers or 
mixtures thereof 
3) 0.1 to 10 wt. %, preferably 0.3 to 2 wt. %, of organo-functional 
silanes, 
4) 0 to 10 wt. %, preferably 0.1 to 5 wt. %, of further conventional size 
constituents and 
5) water to make up to 100 wt. %. 
The polyolefins b1) modified with acid groups are crystalline or amorphous 
polyolefins which are chemically modified, i.e. which contain carboxylic 
acid groups, as are described, for example, in U.S. Pat. No. 3,433,777 and 
U.S. Pat. No. 3,480,580. Crystalline or amorphous polypropylenes 
containing carboxylic acid groups are preferred. Chemical modification of 
the polyolefins generally involves reacting the polyolefin with an 
unsaturated carboxylic acid and/or polycarboxylic acid or the anhydrides, 
chlorides, amides or esters thereof. Examples of such acids or anhydrides 
are maleic acid, fumaric acid, itaconic acid, acrylic acid, methacrylic 
acid, muconic acid, crotonic acid, maleic anhydride, itaconic anhydride 
etc.. Modification with maleic anhydride is preferred. One example of a 
usable, maleic anhydride modified polypropylene is the commercial product 
available from Eastman Chemical (Deutschland) GmbH under the trade name 
EPOLENE.RTM. E 43. The polyolefins b1) modified with acid groups are used 
in a quantity of 60 to 95 wt. %, preferably of 70 to 85 wt. %, relative to 
emulsifiable polyolefin b). 
The emulsifiers b2) are generally anionic, cationic or neutral, low 
molecular weight, oligomeric or polymeric emulsifiers, surfactants or 
protective colloids, which are used in a quantity of 10 to 40 wt. %, 
preferably of 15 to 25 wt. %, relative to emulsifiable polyolefin b). 
Examples of anionic, low molecular weight, oligomeric or polymeric 
emulsifiers or surfactants are alkali metal or alkaline earth metal salts 
of fatty acids, for example sodium salts of saturated fatty acids with 10 
to 21 carbon atoms, sodium salts of unsaturated fatty acids with 12 to 18 
carbon atoms, alkyl ether sulphonates, such as ethers of 
.alpha.-sulpho-.omega.-hydroxypolyethylene glycols with, for example, 
1-methylphenylethylphenol, nonylphenol or alkyl ethers with 12 to 18 
carbon atoms, arylalkyl sulphonates, such as naphthalenesulphonic acids 
provided with linear or branched butyl groups, or alkyl sulphates, such as 
the sodium salts of long-chain sulphuric acid alkyl esters. 
Examples of cationic, low molecular weight, oligomeric or polymeric 
emulsifiers or surfactants are the salts of amines with 8 to 22 carbon 
atoms bearing long-chain alkane residues, which amines were converted with 
acids or by alkylation to the ammonium compounds, together with analogous 
phosphorus and sulphur compounds. 
Examples of non-ionic oligomeric or polymeric emulsifiers or surfactants 
are alkyl polyglycol ethers or esters, such as ethoxylated long-chain 
alcohols, for example with 12 to 18 carbon atoms, bearing saturated or 
unsaturated bonds, ethoxylated castor oil, ethoxylated (coconut) fatty 
acids, ethoxylated soy bean oil, ethoxylated resin or rosin acids, 
ethoxylated and optionally propoxylated diethylene glycol monobutyl ether 
or ethoxylated alkylaryl ethers, such as ethoxylated linear and/or 
branched nonylphenol or octylphenol or benzylated p-hydroxybiphenyl. 
Suitable emulsifiers or surfactants also include ethoxylated long-chain 
alkyl- or alkenylamines, lecithin, reaction products prepared from 
polyethylene glycols and diisocyanates and modified with long-chain 
alkylisocyanates, reaction products of rape seed oil and diethanolamine or 
ethoxylated reaction products prepared from sorbitan and long-chain 
alkane- or alkenecarboxylic acids. 
Finally, so-called protective colloids are also suitable, such as, for 
example, polyvinyl alcohols or water-soluble cellulose derivatives such as 
methylcellulose. 
Suitable bases b3) are alkali metal hydroxides, such as for example sodium 
or potassium hydroxide, or tertiary amines, such as for example 
triethylamine or N,N-dimethylethanolamine. The bases are used in a 
quantity of 1 to 7 wt. %, preferably of 2 to 5 wt. %, relative to b). 
Formulations for polyolefin emulsions and the production thereof are known 
to the person skilled in the art (for example from U.S. Pat. No. 
3,480,580) and are moreover described in detail in publication no. F-302 
from Eastman Chemical Products Inc.. 
The metal salts of the phosphoric acid ester c) are compounds of the 
general formula (I) 
##STR3## 
wherein 
A.sup.1 and A.sup.2 each independently is a monofunctional hydrocarbon 
radical with 8 to 40 carbon atoms, or together are a difunctional 
hydrocarbon radical with 16 to 80 carbon atoms, 
a is a number from 1 to 3 and 
M is an a-valent metal ion. 
Metal ions are, for example, alkali metal ions, such as sodium and 
potassium ions, alkaline earth metal ions, such as magnesium or calcium 
ions, or other metal ions, such as aluminium ions. 
The metal salts are preferably 
compounds of the general formula (II) 
##STR4## 
wherein, 
R.sup.1 is an alkyl radical with 2 to 12 carbon atoms, particularly 
preferably a tert.-butyl radical, 
n is 1 or 2, 
a is 1 to 3 and 
M is an a-valent metal ion, or 
compounds of the general formula (III) 
##STR5## 
wherein 
R.sup.2 to R.sup.5 each independently is an alkyl radical with 2 to 12 
carbon atoms, particularly preferably a tert.-butyl radical in position 4 
and 6, 
a is 1 to 3 and 
M is an a-valent metal ion and 
R.sup.6, R.sup.7 each independently is a hydrogen atom or a methyl radical. 
Sodium 2,2'-methylenebis(4,6-di-tert.-butylphenyl) phosphate is very 
particularly preferred. 
The aqueous dispersion contains a quantity of 0.1 to 15 wt. %, preferably 
of 1 to 7 wt. %, of the metal salts of the phosphoric acid ester. 
Further additives and auxiliary substances which may be considered are 
preferably emulsifiers, surfactants or protective colloids of the type 
stated above and lubricants, anti-ageing agents, anti-oxidants etc.. 
The aqueous dispersions according to the invention are preferably produced 
by combining components a) to d), heating them to temperatures of between 
60.degree. and 200.degree. C., preferably between 90.degree. and 
190.degree. C., and then cooling them. The temperature is preferably 
selected in such a manner that the modified polyolefin (b1) melts at the 
selected temperature. A temperature is particularly preferably selected 
which lies approximately 20.degree. C. above the melting point of the 
modified polyolefin (b1). The process is performed in accordance with 
known methods as are generally used for the production of polyolefin 
emulsions. Details relating to the process are described, for example, in 
publication no. F-302 from Eastman Chemical Products Inc.. 
The aqueous dispersions according to the invention may be used for the 
surface modification of solids, such as for example calcium carbonate, 
talcum, silica gel, barium sulphate, calcium sulphate, kaolin, bentonite, 
iron oxides, titanium dioxide, zeolites, wollastonite, dolomite, zinc 
oxide, magnesium carbonate, molybdenum disulphide, glass and quartz. They 
are preferably used for sizing glass fibers. 
Sizing of glass fibers is known per se to the person skilled in the art. 
The sizes according to the invention contain, together with the aqueous 
dispersions according to the invention, further binders, coupling agents, 
lubricants and auxiliary substances such as wetting agents and anti-static 
agents. The binders, coupling agents, lubricants and auxiliary substances, 
the process for the production of the size, the process for sizing glass 
fibers are known and described, for example, in K. L. Loewenstein, The 
Manufacturing Technology of Continuous Glass Fibres, Elsevier Scientific 
Publishing Corp., Amsterdam, London, New York, 1983. 
Before application to the glass fibers, the size according to the invention 
preferably contains 
1) 2 to 20 wt. %, preferably 4 to 10 wt. %, of solids of the aqueous 
dispersion according to the invention, 
2) 0 to 20 wt .%, preferably 0 to 10 wt. % , of solids of polyolefin, 
polyepoxide, polyester, polyvinyl acetate or polyurethane film formers or 
mixtures thereof, 
3) 0.1 to 10 wt. %, preferably 0.3 to 2 wt. %, of organo-functional 
silanes, 
4) 0 to 10 wt. %, preferably 0.1 to 5 wt. %, of further conventional size 
constituents, and 
5) water to make up to 100 wt. %. 
Use of the dispersions according to the invention for the surface 
modification of solids, in particular for sizing glass fibers, increases 
compatibility between the solids and the matrix olefin and improves 
adhesive properties.

The following examples are intended to illustrate the invention in greater 
detail. 
EXAMPLE 1 
Production of an Aqueous Composition According to the Invention 
216.0 g of maleic acid modified polypropylene (EPOLENE.RTM. E 43, 
commercial product of Eastman Chemical (Deutschland) GmbH), 12.0 g of 
sodium 2,2'-methylenebis(4,6-di-tert.-butylphenyl) phosphate, 54.0 g of 
nonylphenol ethoxylated with 10 mols of ethylene oxide, 10.2 g of 
potassium hydroxide and 1655.8 ml of water are heated in an autoclave to 
170.degree. C., stirred for 60 minutes at this temperature and cooled to 
25.degree. C. The resultant aqueous dispersion is filtered through a 50 
.mu.m woven nylon filter. No residue remains. A finely divided aqueous 
dispersion with a pH of 7 and a viscosity of 5 mPa.s having an indefinite 
storage life is obtained. 
EXAMPLE 2 
Use of the Aqueous Dispersion According to the Invention and Known 
Dispersions in Sizes for Sizing Glass Fibers 
The sizes described in Table 1 are applied with a kiss-roll applicator to 
glass fibers with a diameter of 14 .mu.m. The glass fibers are wound into 
cakes (reels) and then dried for 10 hours at 130.degree. C. Once dry, the 
glass fibers are chopped into 4.5 mm lengths. 
EXAMPLE 3 
Incorporation of the Sized Glass Fibers into Polyolefins 
The components shown in Table 2 are converted into a molding composition in 
an extruder at an extruder temperature of 250.degree. C. and pelletized. 
80.times.10.times.4 mm test bars and tensile bars are produced from the 
molding compositions on a conventional injection molding machine. The bars 
are tested for flexural strength by DIN 53 452, tensile strength by DIN 53 
455 and Izod impact strength at room temperature (ISO 180/IC). 
TABLE 1 
______________________________________ 
Sizes 
Glass fiber 1 
Glass fiber 2 
Size component (invention) 
(Comparison) 
______________________________________ 
.gamma.-Aminopropyltriethoxysilane (wt. %) 
0,6 0,6 
Aqueous dispersion from Example 1 
9,0 -- 
(wt. % of solids) 
Polypropylene dispersion according to 
-- 9,0 
US Pat. No. 3 433 777.sup.*) (wt. % of solids) 
Water (wt. %) 98,4 98,4 
Quantity of size applied in % (determined 
1,10 1,05 
by ashing) 
______________________________________ 
TABLE 2 
______________________________________ 
Molding compositions 
Component (quantities stated in 
parts by weight relative to a total 
Comparison 
Comparison 
quantity of 100 parts by weight) 
A B A B 
______________________________________ 
Polypropylene HOSTALEN .RTM. 
70 65 70 65 
PPN 1060 natural; commercial 
product of Hoechst AG) 
Modified polypropylene 
-- 5 -- 5 
EXXELOR .RTM. PO 1015; 
commercial product of Exxon) 
Glass fiber 1 from Example 2 
30 30 -- -- 
Glass fiber 2 from comparative 
-- -- 30 30 
example 
Flexural strength in MPa 
95 147 77 116 
Tensile strength in MPa 
64 100 53 76 
Impact strength in kJ/m.sup.2 
11 33 9 24 
______________________________________ 
.sup.*) Dispersion prepared from 90 g of emulsifier (NP 7; commercial 
product of Bayer, Leverkusen), 360 g of EPOLENE .RTM. E 43 (commercial 
product of Eastman Chemical Products Inc.), 16.92 g of potassium hydroxid 
and 1100 ml of water; produced in accordance with publication no. F302 
from Eastman Chemical Products Inc., page 16. 
It will be understood that the specification and examples are illustrative 
but not limitative of the present invention and that other embodiments 
within the spirit and scope of the invention will suggest themselves to 
those skilled in the art.