CA1166403A - Process for the manufacture of stable polyol-filler dispersions - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE:
This invention relates to a process for the manufacture of stable, non-sedimenting polyol-filler dispersions.
The polyol-filler dispersions are prepared by the crushing of fillers in situ in polyols employing high localized energies.
The products thus obtained are preferably used for the manufacture of polyurethanes and, in particular, polyurethane foams.

Description

1~66~03 1082 PROCESS FOR THE MANUFACTURE OF STABLE
POLYOL-FILLER DISPERSIONS
Background of the Invention 1 Field of the Invention .
The invention relates to a process for the manufac-ture of stable polyol-filler dispersions. More particularly, this invention relates to polyol-filler dispersions wherein fillers, preferably inorganic fillers, are crushed to particle sizes of less than 7 microns in situ with polyols with high localized energies.

2. Prior Art The manufacture of dispersions of fillers in organic polymers and hydroxyl group containing polyethers is known.
For this purpose, aqueous polymer dispersions are generally mixed with polyethers and the water is subsequently removed.
It was also suggested to produce graft polymers by in situ polymerization of ethylenically unsaturated monomers in possibly ethylenically unsaturated polyethers and to use the obtained product for the manufacture of polyurethanes.
If inorganic fillers are used for the manufacture of polyurethanes, these are normally incorporated in the polyols immediately prior to processing. It has also been attempted to disperse inorganic materials in polyethers. In most cases, such dispersions have very high viscosities which make processing considerably more difficult or even impossible.
~nother disadvantage is that the inorganic fillers, due to their higher specific weight, will sediment more quickly than organic polymers.

The purpose of this invention was the manufacture of storage-stable, non-sedimenting dispersions of fillers in pol~ols which, with a solids content of 10 percent by weight based on the total weight, have a viscosity of less than 2500 centipoises at 25C and with solids contents of 20 percent by weight, have viscosities of less than 5000 centipoises at 25C.
It was found that storage-stable dispersions with the desired properties are obtained if the filler materials are crushed in situ in the polyols.
The object of this invention is therefore a process for the manufacture of stable filler polyol dispersions wherein the fillers are crushed with high localized energy densities to a particle size of less than 7 microns in situ in the polyols with the result that the filler particles are comminuted and thus simultaneously dispersed to form a stable dispersion.
The polyols employed in the above process have functionalities of 2 to 8 and molecular weights of 200 to 8000.
Furthermore, the viscosities of the dispersions thus obtained correspond to those reguired.
The fillers and/or pigments are initially crushed to particle sizes smaller than 100 microns. For this purpose, coarsely grained materials may, for instance, be ground by mechanical mills such as impact disc mills, pinned disc mills, and others. However, it is also possible to obtain particle sizes smaller than 100 microns by other methods, for instance, by reprecipitation.
The fillers and/or pigments pretreated in the above described manner in the presence of polyols and possibly dis-persing agents are now crushed in situ to particle sizes smallerthan 7 microns (wet crushing).

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I 1 664n3 The wet crushing may, for instance, be carried out in mechanical dispersing devices, preferably in dispersing machines having high local energy density with grinding facility such as ball mills, sand mills, netsch mills, bead mills, dyno mills, planetary ball mills, tube mills and attrition mills. Used on a preferable basis are spherical grinding materials which, for instance, may be made of glass, ceramic, metal, or rigid abrasion resistant plastics such as polyamide. The diameter of these spheres should be 0.2 to 8, preferably 0.4 to 5 millimeters.
For the purpose of wet crushing, the filler is mixed with the polyol in such quantities that the resul~ing dispersion has a filler content of 3 to 50 percent by weight, preferably of 3 to 25 percent by weight, based on the overall weight.
The total amount of filler can be mixed with the total amount of polyol and possible dispersing auxiliaries which can be crushed and simultaneously dispersed. However, it is also possible to mix the entire amount of polyol with a certain part of the filler and to crush this mixture to a certain particle size of the filler and to then incorporate the remaining amount of filler in this mixture or preferably to grind a partial amount of polyol with the total amount of filler in the presence of dispersing auxiliaries and to add additional polyol and possibly dispersing auxiliaries during the further course of the grinding process.

1 ~ 66~03 The products are preferably used for the manufacture of polyurethanes and, in particular, polyurethane foams.
By means of the process according to this invention, polyol-filler dispersions are produced which contain 3 to 50 percent by weight, preferably 3 to 25 percent by weight, based on the total weight of polyol. The particle size of the inorganic filler is 0.01 to 7 microns, preferably 0.05 to 1.5 microns. With a solids content of 10 percent by wei~ht, the viscosities of the dispersions are preferably 1000 to 1500 centipoises, at 25C and with a solids content of 20 percent by weight, the viscosities are preferably 1500 to 4000 centi-poises, at 25C and are therefore very well suited for processing on commonly used machinery for the manufacture o~ polyurethanes.
Another advantage is that the filler polyol dispersions produced in accordance with this invention have an extraordinar-ily good storage stability. After storage periods of more than 6 months, no precipitation of solid material could be discerned.
- Suitable polyols which are useful as dispersing media have functionalities of preferably 2 to 4,and molecular weights of preferably 800 to 6000,and in particular 1800 to 3000. Well proven and therefore preferably used are polyesters and, in particular, polyethers. However, other hydroxyl group-containing polymers with the above disclosed molecular weights, for ins~e, polyester amides, polyoxymèthylene and polycarbonates, in particular ~ . . .. .. . _ ___ ~ia ` . 1 t 66'~03 those manufactured from diphenylcarbonates and l,6-hexanediol by~ transesterification may also be employed~
The polyesters may be prepared, for example, by reacting dicarboxylic acids, preferably aliphatic dicarboxylic acids having 2 to 12, preferably 4 to 8, carbon atoms in the alkylene radical with multifunctional alcohols, preferably diols. Examples of the acids include aliphatic dicarboxylic acids such as glutaric acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, and preferably 6uccinic and adipic acid, and aromatic dicarboxylic acids such as phthalic acid and terephthalic acid. Examples of bi- and multifunctional, particularly trifunctional alcohols are: ethylene glycol, diethylene glycol, propylene glycol, trimethylene glycol, dipropylene glycol, l,10-decanediol, glycerine, trimethylolpropane, and preferably l,4-butanediol and 1,6-hexanediol.
The polyesters may have molecular weights of 800 to 3500, preferably 1500 to 2800, and hydroxyl numbers of 35 to 180, preferably 40 to 11 0 .
Most preferably used as polyol~ are polyethers which are produced according to well-known processes from the reaction of one or several alkylene oxides having 2 to 4 carbon atoms in the alkylene radical and a starter molecule which contains 2 to B, preferably 2 to 4, active hydrogen atoms. Suitable alkylene oxides include 1,2- or 2,3-butylene oxide, and preferably, ethylene oxide and propylene oxide.
The alkylene oxides can be used individually, alternatingly ln sequence or in mixtures. Tetrahydrofuran styrene oxide and oxe!tane may also be used. Possible starter molecules are:
water, dicarboxylic acids such as succinic acid, adipic acid, phthalic acid and terephthalic acid, N-mono-, N,N- and N,N'-dialkyl substituted diamines having 1 ~o 4 carbon atoms in the alkyl radical and mono- and dialkyl substituted such as ethylene diamines, propylene diamine, 1,3-propanediamine, 1,4-butanediamine, 1,6-hexamethylene diamine and 4,4'-, 2,4'-and 2,2'-diaminodiphenyl methane, alkanolamines such as ethanolamine, diethanolamine, N-methyl- and N-ethyl-diethanol-amine, and triethanolamine, and hydrazine. Preferably employed as starter molecules are ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, 1,4-butanediol, 1,6-hexanediol, glycerine, trimethylolpropane, pentaerythritol, sorbitol and sucrose.
Preferably used are primarily the di- and/or partic-ularly the trifunctional polyethers having molecular weights of 200 to 8000, preferably of 800 to 6000, hydroxyl numbers of 145 to 800, preferably of 25 to 200, and which contain ethylene oxide as well as propylene oxide units in the oxyalkylene chain and which can be arranged randomly or in block form in the oxyalkylene chain.
Most preferred are polyethers which contain primary hydroxyl groups and particularly trifunctional polyethers with hydroxyl numbers from 20 to 40.
m e organic or inorganic fillers which may be employed in this invention, are basically the known common `" 1 1 6fi~03 organic and inorganic fillers, reinforcing agents, weighting agents, agents for improving the abrasion resistance in paint6, coating materials, etc. For example, inorganic fillers such as silicate minerals of the type of sedimentation 6ilicates such as antlgorite, serpentine, hornblende, amphi-bole, chrisotile, talc; metal oxides such as kaolin, aluminum oxide, titanium oxide and iron oxide; metal salts such as chalk, heavy spar, and inorganic pigments such as cadmium sulfide, zinc sulfide as well as glass, asbesto~ meal and other materials. Preferably used are kaolin (China clay), aluminum silicate and coprecipitates from barium sulfate and aluminum silicate. Possible organic filler~ include coal, kollophonium and cyclopentadienyl resins. The organic and inorganic fillers may be used individually or in mixtures.
For the manufacture of the polyol-filler dispersions according to this invention, dispersing auxiliaries may also be used if required in quantities of 0.1 to 10 percent by weight, preferably of 0.5 to 5 percent by weight, based on the weight of the filler. These include dispersing auxiliaries such as oleic acid amides, esters of higher fatty ac~ds such as mono-, di- and triglycerides of oleic acid, and oxyethyl-ated fatty acids among others.
~ As previously ~entioned, it is of primary im-portance, for the manufactu~re of stable dispersions according to this invention, that the filler materials are crushed with high localized energy densities to particle sizes of less than 7 microns in situ in the polyols particularly particle sizes ranging from O.Ol to 5 microns, preferably 0.05 to 1.5 microns.

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1 1~6403 High local energy densities in the sense of this invention are energy densities of 500 to 3000 kilowatt hours per cubic meter, preferably 2000 to 3000 kilowatts per cubic meter.
The following Examples are provided to further illustrate the invention. All parts are by weight unless otherwise designated.

~, ` I 1~6~03 EXAMPLE t To 500 parts of a product manufactured by the reaction of barium ~ulfate with silicic acid (a calcining lossof 6 percent by weight, SiO content 73 percent and BaSQ4 content 21 percent, pH value according to DIIN-5320o ~ 7.0) and having an average particle size of 70 microns was stirred into 2000 parts of a polyether manufactured by reacting glycerine with propylene oxide and ethylene oxide having a molecular weight of 4900 and a hydroxyl number of 35. This mixture was crushed in a ball mill, the internal wall of which was rubber lined and with glass balls being used as the grinding material, for four hours.
The rotational speed of the ball mill was selected in such a manner that the local energy density was approxi-mately 200~ to 2500 kilowatt hours per cubic meter and that a temperature of 35-C in the dispersions was not exceeded during the dispersion time. Following this, the dispersion was removed from the milI and a sedimentation analysis was carried out. It was determined that 95 percent of the particles contained in the dispersion were smaller than 1 micron and 50 percent of the particles were smaller than 0.5 micron. After

3 months, the storage-stable di`spersion did not show any sedimentation whatsoever~.
~EXAMPLE 2 To 480 parts of a kaolin having a pH value of 5.5 ana a ~pecific weight of 3.6 grams per cubic centimeter, where~n 99.5 percent by we$ght of the particles were smaller . ~, .

. 1 1 66iiQ3 than 10 micron6 and 80 percent by weight of the particles were smaller than 2 microns, was added 1800 parts of a polyether produced by reacting trimethylolpropane with propylene oxide and ethylene oxide having a molecular weight of 5000 and a hy-droxyl number of 32. This mixture was passed five times through a continuously operating ball mill. The overall grinding process took 3 hours. The local energy dens;ty was approximately Z000 to 2500 kilowatt hours per cubic meter. A
6edimentation analysi~ of the resulting dispersion showed that less than 1 percent by weight of the particles had a ~ize greater than 3 microns, approximately 80 percent by weight of the particles were approxima~ely 1 micron in size, and 20 percent by weight of the particles were less than 0.5 micron.
After 4 months, the dispersion did not show any sedimentation.

To 200 parts of a commercially available talc powder containing 62.6 percent by weight of SiO2, 31.4 percent by weight of MgO, 0.20 percent by weight of A12O3,

4.8 percent by weight of water, having a density of 2.77 grams per cubic centimeter, 99 percent of which had grain ~izes smaller than 10 microns, and 85 percent had grain sizes ~maller than 5 microns, was added 800 parts of a polyether prepared by reacting trimethylolpropane with propylene oxide and ethylene oxide, having a molecular weight of 4900 and a hydroxyl number of 35. The mixture was crushed in a continu-ou~ly operating ball mill with glass balls as grinding material ~ball diameter 3 millimeters) ~n 5 passes at 40-C. The ,_ i~ , ~,. . .

I 166~03 grinding process required 4 hours. The local energy density was approximately 600 kilcwattllo~s per cubic meter. A sedimenta-tion analysis of the resulting dispersions showed that 99 percent by weight of the particles were smaller ~han 4 microns.
EXAMPLES 4-9 and COMPARATIVE EXAMPLES A-E

.
Inorganic fillers mixed with a polyether prepared by reacting trimethylolpropane with propylene oxide and ethylene oxide having a molecular weight of 4900 and a hydroxyl number of 35 were crushed in a bead mill ~manufacturer: Drai~) with a local energy density o~ 600 kilcwatt hours per cubic meter.
For the comparative examples, the filler was stirred in with the aid of a rotating disc mixer (rpm 1500) and the mixture was subsequently agitated for 30 minutes. The applied fillers concentrations in the polyether are based on the overall weight. The grinding duration and viscosities ob-tained are summarized in the following Table.

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1 1~6~3 EXAMPLE t0 To 250 parts of a coprecipitate consisting of barium sulfate and silicic acid (BaSO4 content 21 percent and SiO2 content 73 percent~ with an average particle size of 70 microns, was added 1000 parts of a polyester polyol manufactured by poly-condensation of adipic acid and a diol mixture consisting of 1,4-butanediol, 1,5-pentanediol and 1,6-hexanediol with an OH number of 56 and a viscosity of 650 m.Pa.s measured at 75C.
After one hour of intensive mixing and grinding in a dissolver, a milky dispersion was obtained which did not form any sediment after having been stored for 6 months. The particle size of the dispersion was 7 microns maximum: 93 percent of the particles were smaller than 5 microns and 78 percent of the particles were smaller than 3 microns.

Duplicating the procedure in Example 3 but replacing the commercially available talc powder with coal dust or a dicyclopentadienyl resin, storage stable dispersions were also obtained wherein 99 percent of the particles were smaller than 4 microns.

I 1 6S~03 SUPPLEMENT~Y DISCLOSURE
In the principal disclosure, the Applicant has described a process for the manufacture of stable polyol filler dispersions wherein the fillers are crushed with high localized energy densities to a particle size of less than 7 microns in situ in the polyols with the result that the filler particles are comminuted and thus simultaneously dispersed to form a stable dispersion.
Accordlng to the princlpal disclosure, the organic or inorganic fillers may be employed in this invention. Possible organic fillers include coal, kollophonium and cyclopentadienyl resins.
Furthermore and as previously disclosed, high local energy densities in the sense of this invention are energy densities of 500 to 3000 kilowatt hoNrs per cubic meter, prefera-bly 2000 to 3000 kilowatts per cubic meter.
The Applicant has noted from experiment that melamine can be used as an organic filler. It has also been observed that high local energy densities in the sense of this invention are energy densities of l0 to 3000 kilowatt hours per cubic meter. This corresponds with related outputs per volume-power unit of approximately 100 to 2500 kilowatts per cubic meter.
The invention has been carried out with melamine as an organic filler in polyether polyol, use being made of a bead mill or a dissolver for wet crushing. This specific experiment will be better understood by reference to the appended drawings, whereln:
Fig. 1 is a plot of the particle size of melamine powder in a polyether polyol (a) before and (b) after dispersion employing a bead mill.
Figs. 2 and 3 are plots of the particle size of melamine powder in polyether polyol l2) before and (3) after dispersion 1 16~0~

employing a dissolver. I
In Fig. 1 is shown the cumulative percentage of particles ranging over a particle size range (a) before and (bj after dispersion in a bead mill employing a local energy density of 670 kilowatt hours per cubic meter. This dispersion containing 25 percent by weight melamine was storage stable displaying no sedimentation for several months.
In Figs. 2 and 3 is shown the cumulativ~ percentage of particles ranging over a particle size range (2) before and (3) after dispersion in a dissolver employing a local energy density of 15 to 20 kilowatt hours per cubic meter. This dispersion containing 25 percent by weight melamine displayed sedimentation within 24 hours forming a clear supernatant layer.

Claims (6)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A process for the manufacture of stable polyol filler dispersions wherein the fillers in polyols are crushed with high localized energy densities in situ to particle sizes of less than 7 microns, said polyols having functionalities of 2 to 8 and molecular weights of 200 to 8000, and with a solids content of 10 percent by weight based on the total weight, the viscosities of the dispersions thus obtained being less than 2500 centipoises at 25°C and with a solids content of 20 percent by weight, the viscosities being less than 5000 centipoises at 25°C.

2. The process of claim 1 wherein the localized energy densities are 500 to 3000 kilowatt hours per cubic meter.

3. The process of claim 1 wherein the polyols have molecular weights of 200 to 8000 and hydroxyl numbers of 20 to 600.

4. The process of claim 1 wherein polyethers having molecular weights of 800 to 6000 are used as polyols.

5. The process of claim 1 wherein inorganic fillers are used as filler materials.

CLAIMS SUPPORTED BY THE SUPPLEMENTARY DISCLOSURE

6. A process according to claim 1, wherein the localized energy densities are 10 to 3000 kilowatt hours per cubic meter.