Patent Grant
9574153
This invention deals with new compositions of matter that provide lubricant properties when cured into a coating on a substrate.
There are many applications for lubricants and the majority of such applications are satisfied by the use of greases, oils, and such other lubricants. However, there are many applications where it is desirable that the lubricant not be a grease or liquid of any kind, such as oils.
Such applications are, for example, coating wire and cable to allow sufficient pull through when such wire and cable is installed in a building. Another application is a solid coating for arrow shafts such that the arrows can be easily removed from bales and targets.
Additional applications include process equipment that requires a solid lubricant, such as process equipment that is subjected to wear by solid materials. Such lubricant coatings should also have the benefit of anti-abrasion, anti-corrosion and or anti-erosion. Such equipment can be, for example, forming tools, extrusion and compounding equipment, size reduction and size classification equipment, engines, such as diesel, and turbines.
Thus what is disclosed and claimed herein is a composition of matter having the average general formula:
wherein the average molar ratio of x:y:z is 0.25-3:4:0.25-3, W is independently selected from the group consisting essentially of Si, Ti, and Zr, and Al; wherein each R1 is an aryl group with the proviso that there is present at least one R1 group; R is selected from the group consisting essentially of R1, alkyl groups having 1 to 8 carbon atoms, each R2 is a hydroxyl group, an aryl group, an alkoxy group having 1 to 8
carbon atoms, or an
radical;
y has a value of 4;
s has an average value of about 1 to 5;
wherein WOy is derived from W(OR3)4 wherein (OR3) is independently selected from the group consisting of —OCH3, —OCH2CH3, —OCH(CH3)2, —O(CH2)3CH3, —OCH2 CH(C3)2, —O(2-ethylhexyl), acetoxy, and, oximo.
Another embodiment of this invention is a water solution of the composition described just Supra.
Still another embodiment of this invention is a water-alcohol solution of the composition described just Supra.
An additional embodiment is a cured coating having lubricant properties.
The compositions of this invention are low molecular weight polysilicate compositions that have high silanol or alkoxy contents, that is, have a large number of silanols or alkoxy groups in the molecule. By “large number of silanols or alkoxy groups” it is meant that at least half of the Si atoms in the molecule are bonded by hydroxy groups when fully hydrolyzed.
One method for providing the materials of this invention comprises providing the components:
wherein the molar ratio of x:y:z is 0.25-3:4:0.25-3, p and q each independently have a value of 2 or less, R′″ is the same as R3; R″″ is independently selected from the methyl group or the phenyl group, and co-hydrolyzing the components in the presence of a predetermined amount of water, and a catalyst for hydrolysis and condensation.
The components
are commercially available from several sources.
By careful, controlled hydrolysis of the precursor monomers, one can obtain the materials of this invention at very low molecular weights, the detail of which can be found infra in the specification, and in the examples.
The materials have the average general formula
wherein R, R′, R″″, W, x, y, and z all have the meanings set forth Supra, which is derived by the hydrolysis of the silane precursors
in conjunction with the orthosilicate, orthotitanate, orthozirconate or, orthoaluminate, having the general formula {W(OR′″)4}y,
wherein the molar ratio of x:y:z is 0.25-3:4:0.25-3, in a controlled manner to avoid random products.
This hydrolysis is carried out using a stoichiometric or less than stoichiometric amounts of water and a catalyst for hydrolysis. Using stoichiometric amounts of water, or, an amount of water less than stoichiometric, results in low molecular weight materials, which is one of the objectives of the method in this invention.
It is believed by the inventors herein that the key to this invention is the use of the molecule: {W(OR′″)4}y as the third component of this invention. W in the case of this invention is independently selected from the group consisting of Si, Ti, and Zr. Preferred for this invention is Si and Ti and most preferred is Si.
The (OR′″) group is selected from the group consisting of —OCH3, —OCH2CH3, —OCH(CH3)2, —O(CH2)2 CH3, —OCH2CH(CH3)2, —O(2-ethylhexyl), acetoxy, and, oximo. Preferred for this invention are the groups —OCH3, —OCH2CH3, and —OCH(CH3)2, and most preferred are the —OCH3 and —OCH2CH3 groups. Preferred orthosilicates and orthotitanates for this invention are Si(OCH2CH3)4 and Ti(OCH(CH3)2)4.
Stoichiometry is based on the number of hydrolysable groups on the combined components. The reaction is carried out in the presence of base or acid, with acid being the preferred catalyst. The acid catalysts are preferred to be HCl, phosphoric, and acetic acids, with HCl and phosphoric acids being most preferred.
Bases that are useable herein are amines, NaOH, KOH and the like and preferred for this invention is NaOH. The hydrolysis reaction is carried out by combining the components in a predetermined ratio and then adding predetermined amounts of acidic or basic water to the components at a controlled rate to form silanols from the alkoxy moieties. For some end use applications of the inventive materials, a slightly higher molecular weight (higher number of silanol reactive groups) is preferred and in this case, the silicate component is treated for a short period of time by acidic or basic water to cause the silicate component to hydrolyze and mildly condense before the other components are added.
By the preferred means, the following reaction sequence is achieved wherein is the phenyl group:
Subsequent predetermined additions of water would then result in materials having a portion of alkoxy groups and a portion of hydroxy groups on silicon, or if enough water is used, all of the alkoxy groups would hydrolyze and leave only hydroxy groups on silicon. For example,
No heat is generally used in this reaction as higher temperatures (in excess of about 150° C.) may result in a gelation of the reaction mixture. Thus, the reactions are generally run at room temperature. There is a small exotherm from the hydrolysis reaction but the heat is not sufficient to provide problems with the resultant product. No solvents are required in this reaction, but it is within the scope of this invention to utilize solvents. It should be noted that the byproducts of the hydrolysis reaction are alcohol, acetic acid, or oxime. Typically, the products of this reaction do not need filtration.
As mentioned Supra, it is possible to enhance the molecular weight and thereby increase the amount of silanol functionality on the molecule by first mildly hydrolyzing the ortho precursor and then adding the remainder of the components.
Thus, a molecule having the following average formula may be obtained:
One can also provide a material having the formula:
by hydrolyzing the components 1 (CH3O)3Si(CH3), 3 Si(OCH2CH3)4 and 1 (CH3O)3Si— C6H5C6H4.
A preferred material is
The materials are liquids as prepared. In some cases, if preferred, the by-produced alcohols and any residual water can be removed to provide a solid material, and in some cases the solid material is hard and appears to be almost crystalline and in some cases, the material is waxy or paste-like.
For use as lubricant coating materials, the polysilicates are combined with a condensation catalyst and allowed to cure on the appropriate substrate. The cured coating has lubricant properties.
Several samples of materials were provided by the same general procedure which was the following. The appropriate silanes and tetraethylorthosilicate (TEOS) were mixed at room temperature along with a stoichiometric amount, or less than a stoichiometric amount of water to hydrolyze the alkoxy groups present in the silane and polysilicate. The pH was adjusted as shown on the table using NaOH.
The mixtures were allowed to hydrolyze for about one hour.
The following formulas were used as shown in Table I
| Number | Name | Date | Kind |
|---|---|---|---|
| 20070036906 | Reeve | Feb 2007 | A1 |
