Low gloss dry erase paint

Abstract

A dry erase writing surface has a low gloss level of 35-60 that can be utilized as both a writable/erasable dry erase surface and a projection surface, formed by a single component, 100% solids polyurethane, ambient cured, dry erase paint formulation. The paint formulation includes a low NCO isocyanate, a cure accelerating catalyst, a flow, leveling, and defoaming agent, a silica matting agent to reduce the gloss level of the applied coating, and an aliphatic hydrocarbon. The surface is ready for use in 24 hours. The coating has a low VOC of between 49 g/l and 99 g/1. The coating is applied to a prepared surface of a substrate to form a film thickness of 1-3 mils. Marks on the dry erase surface remain virtually invisible after 2500 cycles.

Claims

1. A paint formulation for producing a low gloss dry erase surface, the formulation comprising: a. an isocyanate with low NCO, the NCO being 17% or less by weight of the isocyanate; b. a flow, leveling, and defoaming agent; c. a cure accelerating catalyst; d. a polymer treated thermal silica; and e. an aliphatic hydrocarbon wherein the low gloss dry erase surface has a surface gloss level of less than 60 (60 gloss ASTM D523) and a dry erase durability of at least 2500 cycles.

2. The paint formulation of claim 1, wherein the isocyanate comprises between about 87%-92% by weight of the paint formulation.

3. The paint formulation of claim 1, wherein the aliphatic hydrocarbon is an odorless turpentine substitute.

4. The paint formulation of claim 3, wherein the aliphatic hydrocarbon comprises between about 3%-8% by weight of the paint formulation.

5. The paint of claim 1, wherein the flow, leveling, and defoaming agent is a polyether modified polymethylalkylsiloxane.

6. The paint formulation of claim 5, wherein the flow, leveling, and defoaming agent comprises between about 0.05%-0.06% by weight of the paint formulation.

7. The paint formulation of claim 1, wherein polymer treated thermal silica comprises between about 3%-4% by weight of the paint formulation.

8. The paint of claim 1, wherein the cure accelerating catalyst is a dibutyltin dilaurate solution.

9. The paint formulation of claim 8, wherein the catalyst comprises between about 0.07% and 0.08% by weight of the paint formulation.

Description

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(1) The dry erase paint of the present invention generally is formulated with a mixture of a low NCO isocyanate, a cure accelerating catalyst, a silicone-based flow, leveling, and defoaming agent, a matte additive to reduce the gloss level of the applied coating, and an aliphatic hydrocarbon diluent. The dry erase paint formulation includes the low NCO isocyanate in the range of between about 87%-92% by weight of the formulation, the cure accelerating catalyst in the range of between about 0.07%-0.08% by weight, the silicone-based flow, leveling, and deforming agent in the range of between about 0.05%-0.06% by weight of the formulation, and the aliphatic hydrocarbon diluent in the range of between about 3% and 8% by weight of the formulation.

(2) The low NCO isocyanate has an NCO content of 17% (17.3+/0.5% per specification) or less. The desired isocyanates have a viscosity between 500 and 2500 centipoise. One particularly useful isocyanate for use in connection with the present invention is Basonat HA 2000 available from BASF Corporation, Florham Park N.J.

(3) Normally pure isocyanate in a range around 90% by weight of the total paint formulation is not considered a viable coating option due to a variety of factors. Isocyanate by itself will not dry or cure in a reasonable time period when applied, so components such as driers and catalysts must be added. Adding a mineral spirit solvent to isocyanate as a diluent, adding a flow, leveling, and defoaming agent, and adding a cure accelerating catalyst addresses the drying and curing issues.

(4) The flow, leveling, and defoaming agent added to the formulation, among other attributes controls the generation of carbon dioxide off gassing. The defoaming agent of the present invention formulation is a silicone-based ingredient. Particularly, the defoaming agent is polyether modified polymethylalkylsiloxane. One particularly suitable defoaming agent is Byk 320, a silicone containing surface additive for solvent-borne coating systems with a slight reduction of surface tension, available from BYK Additives Inc., Austin, Tex. Further, by requiring the use of a high density, melamine foam roller cover for the coating application, film thickness and the ultimate surface smoothness can be controlled. By maintaining a wet film thickness of 1-3 mils (calculated film thickness at 200 square feet per quart is 3 mils) the foaming aspect of the isocyanate is kept in check.

(5) The diluent of paint formulation of the present invention serves as a thinning agent and in the formulation of the present invention also reduces surface gloss. The diluent is a turpentine-like aliphatic hydrocarbon. One suitable diluent is Odorless Turpenoid available from Martin F. Weber Company, Philadelphia, Pa. Odorless Turpenoid has the same painting properties and drying time as turpentine yet is free from the strong and characteristic odor. Even with the turpentine-like diluent, the paint of the present invention has low VOC of between 49 g/l and 99 g/l and contains none of the restricted chemical components: acrolein, acrylonitrile, antimony, benzene, butyl benzyl phthalate, cadmium, di (2-ethylhexyl) phthalate, di-n-butyl phthalate, di-n-octyl phthalate, 1,2-dichlorobenzene, diethyl phthalate, dimethyl phthalate, ethylbenzene, formaldehyde, hexavalent chromium, isophorone, lead, mercury, methyl ethyl ketone methyl isobutyl ketone, methylene, chloride, naphthalene, toluene (methylbenzene), 1,1,1-trichloroethane, and vinyl chloride.

(6) With the proper ratio of isocyanate, catalyst, and silicone, as disclosed in the examples below, the paint can also be applied virtually bubble free. One catalyst that is suitable for the present invention is Dabco T-12 (dibutyltin dilaurate, DBTDL) available from Air Products and Chemicals, Inc, Allentown, Pa. Dabco T-12 promotes the urethane (polyol-isocyanate) or gelling reaction for the production of flexible and rigid polyurethane foams, coatings, adhesives, sealants, and elastomers.

(7) In order to impart a matte surface of 35-60 (60 degree gloss/ASTM D523), silica is added to the paint formulation described above. As previously mentioned above, the diluent, Odorless Turpenoid also contributes to the matte surface. Particular, the silica may be Acematt 3300, a polymer-treated thermal silica, characterized by very good matting efficiency combined with high transparency. Acematt 3300 is available from Evonik Corp., Parsippany, N.J.

(8) A coat of the dry erase paint of the present invention may be applied to the substrate by any conventional painting methods such as brushing or rolling. The best results, however, result by rolling using Wooster Pro-Tiz, 9 inch foam roller cover, supplied by Wooster Brush Company, Wooster, Ohio. A suitably smooth dry erase surface may be obtained with a single coat of the dry erase paint applied with a high density foam roller, such as those provided by Wooster Brush Company. that minimizes coating thickness and insures surface smoothness. Ideally this application technique will achieve a desired coating thickness of between about 1-3 mils. If too light a coat is applied the desired dry erase properties may be compromised. Whereas, application of too heavy a coat causes the curing time to be extended and the coverage area for a given volume of paint reduced. Ideally a single coat is applied at the desired thickness.

(9) After the dry erase paint has been applied to the substrate, the resulting dry erase writing surface should be allowed to dry for at least 24 hours (1 day) before using. The drying times depend on ambient conditions. The surface can be dry to the touch in just eight hours. The drying time period allows the necessary cross linking to take place resulting in a high performing writable/erasable surface.

(10) As with any painting project, the surface being painted should be free of dirt, oils, debris, and other contaminants. The area surrounding the surface to be painted should be substantially free of residual dust, particulates, or other construction debris floating in the air because they may adhere to the paint and create unwanted particles that would be detrimental to the suitability of the resultant dry erase writing surface. A smooth surface is desired, and any pretreatment, e.g. sanding, spackling, etc., should be done prior to application of the paint. To obtain the best results, a suitable primer coat should be applied to the surface prior to applying the paint of the present invention. In tests, a coat of Kilz Premium primer, available from Masco Corporation, 21001 Van Born Road, Taylor, Mich., was applied to drywall and permitted to dry for 24 hours before applying the paint of the present invention. Color for the dry erasable surface can be provided by tinting the primer to the desired color under the clear matte coat provided by the paint of the present invention.

(11) Below are five examples of illustrative formulations for the paint formulation of the present invention. Showing the resulting gloss level (60 degree gloss/ASTM D523).

Example #1Gloss Level 35-40

(12) TABLE-US-00001 % by Weight Ingredient Purpose 87%-88% Isocyanate (BASF HA - 2000) Primary Resin/Polymer 0.05%-0.06% Polyether Modified Flow, Leveling and Polymethylalkylsiloxane (Byk 320) Defoaming Agent 0.07%-0.08% Dibutyltin Dilaurate (Dabco T-12) Catylyst to Accelerate Cure 3%-4% Polymer Treated Thermal Silica Matting Agent (Acematt 3300) 7%-8% Aliphatic Hydrocarbon (Turpenoid) Thinning Agent and Gloss Reducer

Example #2Gloss Level 40-45

(13) TABLE-US-00002 % by Weight Ingredient Purpose 88%-89% Isocyanate (BASF HA - 2000) Primary Resin/Polymer 0.05%-0.06% Polyether Modified Flow, Leveling and Defoaming Polymethylalkylsiloxane (Byk 320) Agent 0.07%-0.08% Dibutyltin Dilaurate (Dabco T-12) Catylyst to Accelerate Cure 3%-4 % Polymer Treated Thermal Silica Matting Agent (Acematt 3300) 6%-7 % Aliphatic Hydrocarbon (Turpenoid) Thinning Agent and Gloss Reducer

Example #3Gloss Level 45-50

(14) TABLE-US-00003 % by Weight Ingredient Purpose 89-90 % Isocyanate (BASF HA - 2000) Primary Resin/Polymer 0.05-0.06% Polyether Modified Flow, Leveling and Defoaming Polymethylalkylsiloxane (Byk 320) Agent 0.07-0.08% Dibutyltin Dilaurate (Dabco T-12) Catylyst to Accelerate Cure 3-4 % Polymer Treated Thermal Silica Matting Agent (Acematt 3300) 5-6 % Aliphatic Hydrocarbon (Turpenoid) Thinning Agent and Gloss Reducer

Example #4Gloss Level 50-55

(15) TABLE-US-00004 % by Weight Ingredient Purpose 90-91% Isocyanate (BASF HA - 2000) Primary Resin/Polymer 0.05-0.06% Polyether Modified Flow, Leveling and Defoaming Polymethylalkylsiloxane (Byk 320) Agent 0.07-0.08% Dibutyltin Dilaurate (Dabco T-12) Catylyst to Accelerate Cure 3-4% Polymer Treated Thermal Silica Matting Agent (Acematt 3300) 4-5% Aliphatic Hydrocarbon (Turpenoid) Thinning Agent and Gloss Reducer

Example #5Gloss Level 55-60

(16) TABLE-US-00005 % by Weight Ingredient Purpose 91-92% Isocyanate (BASF HA - 2000) Primary Resin/Polymer 0.05-0.06% Polyether Modified Flow, Leveling and Defoaming Polymethylalkylsiloxane (Byk 320) Agent 0.07-0.08% Dibutyltin Dilaurate (Dabco T-12) Catylyst to Accelerate Cure 3-4% Polymer Treated Thermal Silica Matting Agent (Acematt 3300) 3-4% Aliphatic Hydrocarbon (Turpenoid) Thinning Agent and Gloss Reducer

(17) The resulting dry erase surfaces from Examples 1-5 were tested by erasure of the dry erase markers, and the marks were virtually invisible after 2500 cycles.

(18) The process for formulating the dry erase paint of Example 1 of the present invention is set forth below

(19) TABLE-US-00006 Parts by Range by Ingredient Weight Weight Description Purpose Basonat HA 88 30-99 Homopolymer of Primary 2000 Hexamethylene Resin/Polymer Diisocyante Combine the following under dry atmosphere, high speed disperse

(20) TABLE-US-00007 Parts by Range by Ingredient Weight Weight Description Purpose Dabco 0.08 0.01-1.00 Dibutyltin Dilaurate Catylyst to T-12 (Substitute Tin Octoate Accelerate or Bismuth Octoate Cure Byk 320 0.06 0.01-1.00 Polyether Modified Flow, Polymethylalkylsiloxane Leveling, Solution and Defoaming Agent Mix at high speed for 10 minutes. Pour the above mixture over the following matting agent, which is in a separate drum.

(21) TABLE-US-00008 Parts by Range by Ingredient Weight Weight Description Purpose Acematt 3300 4 1-10 Polymer Treated Thermal Matting Silica Agent After liquid mixture (first three components) is added to the Acematt, mix at high speed for 4.50 minutes. Add the following while still being dispersed.

(22) TABLE-US-00009 Parts by Range by Ingredient Weight Weight Description Purpose Odorless 8 2-15 Turpentine Substitute, Thinning Agent Turpenoid Free from Strong and and Gloss Characteristic Odor - Reducer Aliphatic Hydrocarbon Continue mixing at high speed for 15 minutes. Cast three mil film; check for craters, trash, film clarity, and color. Fill under dry atmosphere.

(23) While this invention has been described with reference to preferred embodiments thereof, it is to be understood that variations and modifications can be affected within the spirit and scope of the invention as described herein and as described in the appended claims.