CA1161183A - Epoxy coating powders with wrinkle finishes - Google Patents
Epoxy coating powders with wrinkle finishesInfo
- Publication number
- CA1161183A CA1161183A CA000396725A CA396725A CA1161183A CA 1161183 A CA1161183 A CA 1161183A CA 000396725 A CA000396725 A CA 000396725A CA 396725 A CA396725 A CA 396725A CA 1161183 A CA1161183 A CA 1161183A
- Authority
- CA
- Canada
- Prior art keywords
- coating
- epoxy resin
- curing agent
- range
- resin
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Abstract
ABSTRACT OF THE DISCLOSURE
An epoxy coating powder for application by fusion coating processes produces a coating of low gloss and randomly developed wrinkle surface patterning. A typical formulation comprises a major weight proportion of epoxy resin type 3 of which about 15% comprises such resin compounded with 5% poly-alkylacrylate flow promoter, about 18% of the total weight of the resin being methylene disalicylic acid, and from about 42%
to 53% of resin weight being filler. A BCl3 amine catalyst is incorporated and the materials are melt-mixed, extruded to pellets, and the pellets ground to pass 60 mesh screen.
Cure of the applied coating is effected at about 150°C to 200°C for from 20 to 10 minutes. Compositions capable of producing the wrinkle pattern are characterized by a gel time at 205°C in the range of from about 30 to 70 seconds and exhibit inclined plate flow at 150°C of from about 50 mm to 80 mm.
An epoxy coating powder for application by fusion coating processes produces a coating of low gloss and randomly developed wrinkle surface patterning. A typical formulation comprises a major weight proportion of epoxy resin type 3 of which about 15% comprises such resin compounded with 5% poly-alkylacrylate flow promoter, about 18% of the total weight of the resin being methylene disalicylic acid, and from about 42%
to 53% of resin weight being filler. A BCl3 amine catalyst is incorporated and the materials are melt-mixed, extruded to pellets, and the pellets ground to pass 60 mesh screen.
Cure of the applied coating is effected at about 150°C to 200°C for from 20 to 10 minutes. Compositions capable of producing the wrinkle pattern are characterized by a gel time at 205°C in the range of from about 30 to 70 seconds and exhibit inclined plate flow at 150°C of from about 50 mm to 80 mm.
Description
This invention relates to coatings applied bv fusion coating processes and more particularly to epoxy coating powders that yield wrinkled finishes.
The Field of the Invention The coating compositions of this invention are dry, free-flowing powders that may be used in fusion coating processes.
"Fusion coating processes" are herein defined as those coating processes in which coating powders are distributed over a substrate (which may be hot or cold) and heat, supplied either from the sub-strate or from an external source, fuses the powders into a contin-uous film. Examples of fusion coating processes include fluidized bed, electrostatic spray, hot flocking (with or without electrostatic spray), and cloud chamber processes. When coating powders are based upon heat curing resins, as is the case of the epoxy resins of this invention, sufficient heat in excess of that required to fuse the powders must be available to cure the coatings and fully develop their physical and chemical properties.
The coating compositions of this invention are distinguished in that when coated onto a substrate, they produce coatings of low gloss with a randomly developed wrinkled surface. Wrinkled surfaces of this type are desired in many applications and are commonly applied to office equipment such as typewriters, staplers, dictating equipment, file cabinets, and the like. In addition to being aesthetically pleasing, these finishes have certain utilitarian functions in that they have low gloss (i.e. appear not shiny), they do not show scratches, and they hide surface defects of a substrate even when applied in thin films.
Wrinkle finishes conventionally are applied Erom solvent-based paints, usually using two coats, to establish a compoundsystem in which the surface sets up first. When the rest of the coating sets up, the resulting shrinkages deform the previously set surface and cause a fine wrinkle pattern to develop on the surface of the coating.
Disclosure of the Invention .
It is the object of this invention to formulate epoxy coating powders which will yield coatings having low gloss and a randomly developed wrinkle pattern on the surface.
The invention is based on the discovery that this objective can be achieved through the use of methylene disalicylic acid as the curing agent for a formulation comprising epox~ resin. Other-wise the formulation of the heat curable epoxy coating powder is somewhat typical of a standard decorative epoxy coating except that special care must be taken to adjust the rate of cure - namely, gel time - and the melt viscosity.
An essential property that must be considered when formulating a coating powder is the ability of the powder to fuse into a uniform, continuous and void-free film. As a guide to formulation chemists, two relatively simple test procedures have been established to measure the ability of a coating powder to fuse over a substrate.
One of these is gel time which provides a measure of the reactivity of a given system; and the other is inclined plate flow which is a combined measure of both the reactivity and melt viscosity of the coating powder.
ASTM Specification D-3451 (14) defines a procedure for measuring gel time in which a piece of aluminum foil is placed on a hot plate and heated to a given temperature, e.g. 190C. A small quantity of powder is dropped onto the heated foil and stroked with a tongue depressor until continuous and readily breakable filaments are formed when the depressor is lifted from the foil.
The elapsed time for this to occur is measured in seconds and is the gel time.
The Inclined Plate Flow Test is defined in ASTM D-3451 (17).
In this test a small pellet of powder is placed on a glass or tin plate and inserted into a heated oven, e~g. 150C. After the pellets and the plate h~ave reached temperature equilibrium, the oven rack on which the plate rests is tilted to a 65 angle without opening the oven. After 30 minutes, the plate is removed from the oven, allowed to cool to room temperature and the length of the flow measured in millimeters. The distance the coating flows is dependent on the initial melt viscosity, rate of reaction, and the temperature at which the test is conducted. If the flow is too great, the coating may be expected to run and sag on a substrate;
on the other hand, if the flow is too small, a rough, discontinuous, nonadherent film will probably result.
To obtain the desired wrinkled finish, it has been found that the gel time should be adjusted to be in a range of from about 30 to 70 seconds when measured at 205C. and the inclined plate flow should be in a range of from about 50 to 80 mm when measured at 150C. If the gel time or the inclined pla-te flow does not fall within these limits, the desired wrinkled finishes of this invention are not obtained.
It is generally true that the gel time and the inclined plate flow are a direct function of molecular weight and functionality of the epoxy resin. Melt viscosity and -the inclined plate flow are also influenced by fi]lers which generally increase the viscosity depending on the amount used, the particle size, the surface area of and the surface chemistry of the fillers. sy judiciously balan-cing the functionality and the molecular weight of the resin in combination with the selection of the curing agent, catalyst system, and fillers, it is well within the skill of a formulating chemist to arrive at a coating powder that has gel tlmes and inclined plate flows that will be useful in the practice of this invention.
Summary Statement of the Invention The invention essentially contemplates the formulation of a novel powdered coating composition which is capable of producing a wrinkle-patterned finish when cured on a substrate, the compos-ition comprising a heat reactive epoxy resin, a curing agent, a catalyst, and filler substances, wherein the curing agent is methylene disalicylic acid.
In a principal aspect the invention is embodied in a coating composition of the type above mentioned wherein the curing agent, methylene disalicylic acid comprises about 18 parts by weight per 100 parts of epoxy resin.
In a further aspect the composition is characterized by a flow in the range of from about 50 to about 80 mm when tested by the inclined plate flow test method, and by a gel time which is in the range of from about 30 to 70 seconds when tested by the gel time test method.
Examples and Procedure In the examples which follow, the epoxy resins used are type 3, low viscosity epoxy resins. ~ore specifically, they are ~6~3 epoxies of the epichlorohydrinbisphenol-A type having epoxy equivalent weights of from about 600 to 750, a functionality of about 2, and a Gardner-Holt viscosity in the range of from about K to L. The preferred catalyst is a Lewis acid type and in the examples a boron trichloride amine complex was used. The curing agent, which is critical in the practice of this invention, is methylene disalicylic acid and is used in approximately stoichio-metric quantities. Having defined the above parameters, final adjustment of the gel time and inclined plate flow was obtained by the selection of the kind and amount of fillers, including the pigments, used in the system.
E X A M P L E
A coating powder was prepared in accordance with this invention by initially blending the following ingredients:
Material Parts per Hundred of Resin (PHR) 1. Epoxy low viscosity type 85 3 (Dow XD-9046)
The Field of the Invention The coating compositions of this invention are dry, free-flowing powders that may be used in fusion coating processes.
"Fusion coating processes" are herein defined as those coating processes in which coating powders are distributed over a substrate (which may be hot or cold) and heat, supplied either from the sub-strate or from an external source, fuses the powders into a contin-uous film. Examples of fusion coating processes include fluidized bed, electrostatic spray, hot flocking (with or without electrostatic spray), and cloud chamber processes. When coating powders are based upon heat curing resins, as is the case of the epoxy resins of this invention, sufficient heat in excess of that required to fuse the powders must be available to cure the coatings and fully develop their physical and chemical properties.
The coating compositions of this invention are distinguished in that when coated onto a substrate, they produce coatings of low gloss with a randomly developed wrinkled surface. Wrinkled surfaces of this type are desired in many applications and are commonly applied to office equipment such as typewriters, staplers, dictating equipment, file cabinets, and the like. In addition to being aesthetically pleasing, these finishes have certain utilitarian functions in that they have low gloss (i.e. appear not shiny), they do not show scratches, and they hide surface defects of a substrate even when applied in thin films.
Wrinkle finishes conventionally are applied Erom solvent-based paints, usually using two coats, to establish a compoundsystem in which the surface sets up first. When the rest of the coating sets up, the resulting shrinkages deform the previously set surface and cause a fine wrinkle pattern to develop on the surface of the coating.
Disclosure of the Invention .
It is the object of this invention to formulate epoxy coating powders which will yield coatings having low gloss and a randomly developed wrinkle pattern on the surface.
The invention is based on the discovery that this objective can be achieved through the use of methylene disalicylic acid as the curing agent for a formulation comprising epox~ resin. Other-wise the formulation of the heat curable epoxy coating powder is somewhat typical of a standard decorative epoxy coating except that special care must be taken to adjust the rate of cure - namely, gel time - and the melt viscosity.
An essential property that must be considered when formulating a coating powder is the ability of the powder to fuse into a uniform, continuous and void-free film. As a guide to formulation chemists, two relatively simple test procedures have been established to measure the ability of a coating powder to fuse over a substrate.
One of these is gel time which provides a measure of the reactivity of a given system; and the other is inclined plate flow which is a combined measure of both the reactivity and melt viscosity of the coating powder.
ASTM Specification D-3451 (14) defines a procedure for measuring gel time in which a piece of aluminum foil is placed on a hot plate and heated to a given temperature, e.g. 190C. A small quantity of powder is dropped onto the heated foil and stroked with a tongue depressor until continuous and readily breakable filaments are formed when the depressor is lifted from the foil.
The elapsed time for this to occur is measured in seconds and is the gel time.
The Inclined Plate Flow Test is defined in ASTM D-3451 (17).
In this test a small pellet of powder is placed on a glass or tin plate and inserted into a heated oven, e~g. 150C. After the pellets and the plate h~ave reached temperature equilibrium, the oven rack on which the plate rests is tilted to a 65 angle without opening the oven. After 30 minutes, the plate is removed from the oven, allowed to cool to room temperature and the length of the flow measured in millimeters. The distance the coating flows is dependent on the initial melt viscosity, rate of reaction, and the temperature at which the test is conducted. If the flow is too great, the coating may be expected to run and sag on a substrate;
on the other hand, if the flow is too small, a rough, discontinuous, nonadherent film will probably result.
To obtain the desired wrinkled finish, it has been found that the gel time should be adjusted to be in a range of from about 30 to 70 seconds when measured at 205C. and the inclined plate flow should be in a range of from about 50 to 80 mm when measured at 150C. If the gel time or the inclined pla-te flow does not fall within these limits, the desired wrinkled finishes of this invention are not obtained.
It is generally true that the gel time and the inclined plate flow are a direct function of molecular weight and functionality of the epoxy resin. Melt viscosity and -the inclined plate flow are also influenced by fi]lers which generally increase the viscosity depending on the amount used, the particle size, the surface area of and the surface chemistry of the fillers. sy judiciously balan-cing the functionality and the molecular weight of the resin in combination with the selection of the curing agent, catalyst system, and fillers, it is well within the skill of a formulating chemist to arrive at a coating powder that has gel tlmes and inclined plate flows that will be useful in the practice of this invention.
Summary Statement of the Invention The invention essentially contemplates the formulation of a novel powdered coating composition which is capable of producing a wrinkle-patterned finish when cured on a substrate, the compos-ition comprising a heat reactive epoxy resin, a curing agent, a catalyst, and filler substances, wherein the curing agent is methylene disalicylic acid.
In a principal aspect the invention is embodied in a coating composition of the type above mentioned wherein the curing agent, methylene disalicylic acid comprises about 18 parts by weight per 100 parts of epoxy resin.
In a further aspect the composition is characterized by a flow in the range of from about 50 to about 80 mm when tested by the inclined plate flow test method, and by a gel time which is in the range of from about 30 to 70 seconds when tested by the gel time test method.
Examples and Procedure In the examples which follow, the epoxy resins used are type 3, low viscosity epoxy resins. ~ore specifically, they are ~6~3 epoxies of the epichlorohydrinbisphenol-A type having epoxy equivalent weights of from about 600 to 750, a functionality of about 2, and a Gardner-Holt viscosity in the range of from about K to L. The preferred catalyst is a Lewis acid type and in the examples a boron trichloride amine complex was used. The curing agent, which is critical in the practice of this invention, is methylene disalicylic acid and is used in approximately stoichio-metric quantities. Having defined the above parameters, final adjustment of the gel time and inclined plate flow was obtained by the selection of the kind and amount of fillers, including the pigments, used in the system.
E X A M P L E
A coating powder was prepared in accordance with this invention by initially blending the following ingredients:
Material Parts per Hundred of Resin (PHR) 1. Epoxy low viscosity type 85 3 (Dow XD-9046)
2. Epoxy type 3 with 5~ poly- 15 alkylacrylate flow promoter (Shell DRH-203)
3. Methylene Disalicylic Acid 18 (Tenneco)
4. Sparmite (BaSO4) Filler 50
5. Carbon Black Filler 3 (City Service Raven #22)
6. BC13 Amine Catalyst 0.5 (Ciba Geigy XU-213) The above materials weré melt-mixed in an extruder and the extrudate chopped and ground to a fine powder that was passed through a 60 mesh screen (U.S. standard).
Precleaned steel test panels (from "Q" Panel Co.) of about 3 by 6 by 0.032 inch (7.6 cm x 15.2 cm x 0.08 cm) were coated using standard electrostatic spray techniques and baked in an oven at a temperature of about 190C for lG minutes. There is no great criticality to the time and temperature of the cure and quite generally a useful range with the above formulation is from about 150C at 20 minut~s to about 200C for 10 minutes.
Samples so prepared had a gloss in the range of from 0 to 10%
and a well-developed, random, finely-wrinkled patterned surface.
E X A M P L E II
The following ingredients were mixed, a coating powder was prepared and panels were coated in a manner identical to Example I.
Material Phr 1. Expoxy low viscosity, type 3 85 (Dow XD-9046) 2. Epoxy type 3 with 5% polyalkyl- 15 acrylate flow promoter (Shell DRH-203) 3. Methylene Disalicylic Acid 18 (Tenneco) 4. Tio2 Pigment 40 (DuPont R-900) 5. Black Pigment 0.7 (DeGussa FW-200) 6. Blue Pigment 0.5 (Whittiker Clark UB-5005)
Precleaned steel test panels (from "Q" Panel Co.) of about 3 by 6 by 0.032 inch (7.6 cm x 15.2 cm x 0.08 cm) were coated using standard electrostatic spray techniques and baked in an oven at a temperature of about 190C for lG minutes. There is no great criticality to the time and temperature of the cure and quite generally a useful range with the above formulation is from about 150C at 20 minut~s to about 200C for 10 minutes.
Samples so prepared had a gloss in the range of from 0 to 10%
and a well-developed, random, finely-wrinkled patterned surface.
E X A M P L E II
The following ingredients were mixed, a coating powder was prepared and panels were coated in a manner identical to Example I.
Material Phr 1. Expoxy low viscosity, type 3 85 (Dow XD-9046) 2. Epoxy type 3 with 5% polyalkyl- 15 acrylate flow promoter (Shell DRH-203) 3. Methylene Disalicylic Acid 18 (Tenneco) 4. Tio2 Pigment 40 (DuPont R-900) 5. Black Pigment 0.7 (DeGussa FW-200) 6. Blue Pigment 0.5 (Whittiker Clark UB-5005)
7. BC13 Amine Catalyst 0.5 (Ciba Geigy XU-213) The difference between this example and Example I is that the color of the coating was changed from the black of Example I to a gray-blue by the use of a different pigment system. Note that since in this Example II a high concentration of pigment was required (41.2 phr) no other filler was needed to obtain desired inclined plate flow and gel times. This contrasts to Example I
where the pigments used totalled only ~.5 phr and it was necessary to add 50 phr of barium sulphate filler to bring the inclined plate flow and gel times within acceptable limits.
The surface characteris~ics of -the coating of this Example II
were the same as those of Example I with the exception, of course, that they were of a different color.
The drawing forming part of this specification is an enlarge-ment of a photograph taken of a panel coated with the powder of Example II. The ruler indicates the degree of enlargement.
where the pigments used totalled only ~.5 phr and it was necessary to add 50 phr of barium sulphate filler to bring the inclined plate flow and gel times within acceptable limits.
The surface characteris~ics of -the coating of this Example II
were the same as those of Example I with the exception, of course, that they were of a different color.
The drawing forming part of this specification is an enlarge-ment of a photograph taken of a panel coated with the powder of Example II. The ruler indicates the degree of enlargement.
Claims (6)
1. A powdered coating composition adapted to provide a wrinkled finish, comprised of a heat reactive epoxy resin, a curing agent, a catalyst, and fillers, the improvement being that the curing agent is methylene disalicylic acid.
2. A powdered coating composition according to Claim 1 wherein the inclined plate flow is in a range of from about 50 to 80 mm.
3. A powdered coating composition according to Claim 1 in which the gel time is in a range of from about 30 to 70 seconds.
4. A method for obtaining a wrinkled surface of a coating when applying the coating to a substrate by a fusion coating process with heat reactive epoxy resin, wherein the epoxy resin composition includes methylene disalicylic acid as the curing agent.
5. A method for obtaining a wrinkled surface of a coating when applying the coating to a substrate by a fusion coating process using a powdered heat reactive epoxy resin composition, which comprises preparing by melt-mixing a composition comprising 100 parts low viscosity type 3 epoxy resin containing polyalkylacrylate flow promoter, about 18 parts methylene disalicylic acid curing agent, from about 42 to about 53 parts of filler and pigment, and a boron trichloride amine complex catalyst, extruding the composition and forming pellets, grinding the pellets to a powder and forming a coating film of fused particles on a substrate, and curing the coating by heat.
6. The method of Claim 5 wherein the epoxy resin is of the epichlorohydrinbisphenol-A type having epoxy equivalent weights of from about 600 to 750, a functionality of about 2, and a Gardner-Holt viscosity in a range of from about K to L.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000396725A CA1161183A (en) | 1982-02-22 | 1982-02-22 | Epoxy coating powders with wrinkle finishes |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000396725A CA1161183A (en) | 1982-02-22 | 1982-02-22 | Epoxy coating powders with wrinkle finishes |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1161183A true CA1161183A (en) | 1984-01-24 |
Family
ID=4122129
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000396725A Expired CA1161183A (en) | 1982-02-22 | 1982-02-22 | Epoxy coating powders with wrinkle finishes |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1161183A (en) |
-
1982
- 1982-02-22 CA CA000396725A patent/CA1161183A/en not_active Expired
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4341819A (en) | Epoxy coating powders with wrinkle finishes | |
| EP1907453B1 (en) | Powder coating materials | |
| US5721052A (en) | Textured epoxy powder coating compositions for wood substrates and method of coating wood therewith | |
| US11925957B2 (en) | Two-coat single cure powder coating | |
| GB2194539A (en) | Pvdf-based powder coatings | |
| EP2828418B1 (en) | Two-coat single cure powder coating | |
| MX2008007547A (en) | Low gloss coil powder coating composition for coil coating. | |
| RU2211848C2 (en) | Method for hardening powder-like lacquer | |
| US5212263A (en) | Textured epoxy powder coating | |
| US6743379B2 (en) | Antistatic powder coating compositions and their use | |
| US20040157961A1 (en) | Curable coating powders and powder coatings formed therefrom | |
| CA1129587A (en) | Saturated cross-linkable composition | |
| EP2113537A1 (en) | Powder coating composition | |
| CA1161183A (en) | Epoxy coating powders with wrinkle finishes | |
| EP3239226B1 (en) | Particulate coating | |
| AU2006331758B2 (en) | Powder coating composition suitable for thermo-sensitive substrates | |
| WO1983004195A1 (en) | Epoxy coating powders with wrinkle finishes | |
| JP2002538282A (en) | Powder coating composition | |
| JPH04506088A (en) | Powder composition for undercoating suitable for poly(vinylidene fluoride)-based finishing paints | |
| SU407935A1 (en) | EPOXY POWDER COMPOSITION | |
| JPH03503652A (en) | Method of manufacturing powder coatings for the production of matte or satin surfaces | |
| MXPA98009369A (en) | Powder coating, rough finish, with pat control | |
| MXPA97003116A (en) | Coating compositions in epoxitexturized powder for wooden substrates and metodopara revestira wood with mis | |
| JPH04337365A (en) | Production of polyphenylene sulfide composition for powder coating use |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |