Silica-based matting formulations and methods of making and using the same
Improved coating formulations containing silica based matting agents in the form of a blend of low pore volume silica particles and high pore volume silica particles are disclosed. The matting formulations are useful in waterborne coating compositions to provide exceptional properties to a coated substrate. Films resulting from the coating formulations containing silica-based matting agents on a substrate unexpectedly provide improved chemical resistance to the surface of the substrate, in particular wood or plastics. Methods of making and using the silica-based matting formulations are also disclosed.
1 . A matting formulation for aqueous coating composition comprising high pore volume silica particles blended with an amount of low pore volume silica particles that is sufficient to provide, when the matting formulation is incorporated into an aqueous coating composition and dried onto a substrate to form a film, the film having increased chemical resistance at a 60° gloss value target, wherein the high pore volume silica particles have a median pore volume of greater than 0.80 cc/g as determined by Barrett-Joyner-Halenda (BJH) method and the low pore volume silica particles have a median pore volume equal to or less than 0.80 cc/g or less as determined by the BJH method, wherein said low pore volume silica particles are present in an amount of from about 1.0 weight percent (wt %) to about 99.0 wt %, and said high pore volume silica particles are present in an amount of from about 99.0 wt % to about 1.0 wt %, based on a total weight of said low pore volume silica particles and said high pore volume silica particles.
2 . The matting formulation of claim 1 , wherein the 60° gloss value target is between about 3.0 and about 30.0 as measured using a portable Micro-TRI-Gloss meter.
3 . The matting formulation of claim 1 , wherein, when incorporated into the aqueous coating composition and applied onto a substrate, enables the aqueous coating composition to form a film having a chemical resistance rating of from 3 to 5 within a scale of 1 to 5 using test method EN 12720 or DIN68861-1.
4 . The matting formulation of claim 1 , wherein the film is a clear coat film.
5 . The matting formulation of claim 1 , wherein the substate is wood, plastics, or black chart paper.
6 . The matting formulation of claim 1 , wherein the aqueous coating composition, when applied onto a plain, smooth and non-penetrating black chart paper and dried, forms a film having a 50/50 water/ethanol damage 1 hr AL* value equal to or less than 10.0 units as measured using a portable Spectro-Guide 45/0 colorimeter.
7 . The matting formulation of claim 1 , wherein the aqueous coating composition, when applied onto a plain, smooth and non-penetrating black chart paper and dried, forms a film having a film clarity AL* equal to or less than 7.0 units as measured using a portable Spectro-Guide 45/0 colorimeter.
8 . The matting formulation of claim 1 , wherein the median pore volume of the low pore volume silica particles differs from the median pore volume of the high pore volume silica particles by at least 0.1 cc/g.
9 . The matting formulation of claim 1 , wherein said low pore volume silica particles have a median pore volume of from about 0.01 cc/g to 0.79 cc/g as determined by the BJH method.
10 . The matting formulation of claim 1 , wherein said high pore volume silica particles have a median pore volume of from 0.80 cc/g to about 2.40 cc/g as determined by the BJH method.
11 . The matting formulation of claim 1 , wherein said high pore volume silica particles and said low pore volume silica particles consist essentially of silica.
12 . The matting formulation of claim 1 , wherein said low pore volume silica particles further comprise one or more first waxes in an amount sufficient to at least partially fill pores of said low pore volume silica particles.
13 . The matting formulation of claim 12 , wherein said high pore volume silica particles further comprise one or more second waxes in an amount sufficient to at least partially fill pores of the high pore volume silica particles.
14 . The matting formulation of claim 13 , wherein each of said one or more first waxes and said one or more second waxes independently comprises a hydrocarbon wax, a paraffin wax, a polyethylene wax, a polypropylene wax, a plant wax, an animal wax, or any combination thereof.
15 . The matting formulation of claim 1 , wherein each of said low pore volume silica particles and said high pore volume silica particles independently comprises silica gel, precipitated silica, fumed silica particles, or any combination thereof.
16 . The matting formulation of claim 1 , wherein said low pore volume silica particles and said high pore volume silica particles are free-flowing particles.
17 . A method of preparing the matting formulation of claim 1 , said method comprising:
combining the low pore volume silica particles and the high pore volume silica particles to form a blend of the low pore volume silica particles and the high pore volume silica particles.
18 . The method of claim 17 , further comprising: reducing the particle size of the low pore volume silica particles or the high pore volume silica particles to obtain silica particles having a final particle size of less than 100 microns (pm), and said reducing step results in low pore volume silica particles or high pore volume silica particles having a final particle size of less than about 45.0 pm.
19 . A coating composition comprising the matting formulation of claim 1 .
20 . A substrate coated with the coating composition of claim 19 .