GB1583539A - Epoxy resin powder coating composition - Google Patents
Epoxy resin powder coating composition Download PDFInfo
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- GB1583539A GB1583539A GB20448/78A GB2044878A GB1583539A GB 1583539 A GB1583539 A GB 1583539A GB 20448/78 A GB20448/78 A GB 20448/78A GB 2044878 A GB2044878 A GB 2044878A GB 1583539 A GB1583539 A GB 1583539A
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Classifications
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G59/00—Polycondensates containing more than one epoxy group per molecule; Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups
- C08G59/18—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing
- C08G59/40—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing characterised by the curing agents used
- C08G59/62—Alcohols or phenols
- C08G59/621—Phenols
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G59/00—Polycondensates containing more than one epoxy group per molecule; Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups
- C08G59/18—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing
- C08G59/20—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing characterised by the epoxy compounds used
- C08G59/32—Epoxy compounds containing three or more epoxy groups
- C08G59/38—Epoxy compounds containing three or more epoxy groups together with di-epoxy compounds
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/34—Silicon-containing compounds
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L33/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
- C08L33/04—Homopolymers or copolymers of esters
- C08L33/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, which oxygen atoms are present only as part of the carboxyl radical
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L63/00—Compositions of epoxy resins; Compositions of derivatives of epoxy resins
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D163/00—Coating compositions based on epoxy resins; Coating compositions based on derivatives of epoxy resins
Description
(54) EXPOXY RESIN POWDER COATING COMPOSITION
(71) We, E. I. DU PONT DE NEMOURS AND COMPANY, a Corpora- tion organised and existing under the laws of the State of Delaware, United States of
America, located at Wilmington, State of Delaware, United States of America, do hereby declare the invention for which we pray that a patent may be granted to us and the method by which it is to be performed to be pattictlarly described in and by
The following statement: This invention is related to thermosening powder coating compositions and particularly to compositions containing epoxy resins.
Epoxy resin powder coating compositions which are capable of being crosslinked and various agents which effect the crosslinking are well known. The prior an contains numerous references to compositions which contain epoxy polymers and to conventional crosslinking agents such as anhydrides or amines.
United States Patent 3,882,064 issued May 6, 1975 to W. Pregmon, discloses thermosetting powder coating compositions based on an epoxy resin of the epichloro hydrin-bisphenol-A type crosslinked by dicyanidiamide. Similar powder coatings are shown by Nagel, United States Patent 3,028,251, issued April 3, 1962; and Parry,
United States Patent 3,400,098, issued September 3, 1968. Dlicyandiamide-cured compositions can be water sensitive and therefore are not well suited to be pipe coatings.
No disclosure is made in these patents as to the resistance of their respective combo; sitions to adhesion loss under cathodic protection.
Powder coatings which cure rapidly and have resistance to adhesion loss when subjected to cathodic protection are particularly demanded by the pipe industry. The prior art coatings capable of curing in less than two minutes at 2000C have been commonly found to lose adhesion when subjected to cathodic protection. Pipes are often subjected to cathodic protection, after 'burial in the ground, by connecting them to the negative terminal of a direct voltage source. It is important that the coating not lose adhesion under these conditions.
United States Patent 3,819,564, issued June 25, 1974 to W. Gindrup and A. J.
Siegmund, Jr., discloses thermosetting powder coating compositions based on epichloro- hydrin-bisphenol-A epoxy resins cured by aromatic anhydrides and hydroxypyridines.
This composition is said to cure in 45 seconds at 200-2300C and has acceptable resistance to adhesion loss during cathodic protection. However, its flexibility is less than that exhibited by coatings which require more than two minutes to cure.
The use of blends of epichlorohydalinXbisplhenol-A epoxies and novolac pones in powder coating compositions is shown, for example, in United States Patent 3,484,398, issued December 16, 1969 to W. I. Childs in which a silica filler and anhydride curing agent were used. These compositions, formulated to serve either a molding or coating function, are deficient with respect to certain desirable coating composition propeies, notably cure-time and flexibility, when compared to compositions designed for use solely as coatings.
The use of curing agents other than the conventionally used anhydrides and amines is also part of the art. An agent, believed to be a hydroxy-containing aromaticaliphatic ether, specially designed for use in curing epoxy resin powder coatings, is shown in Dow Chemical Company Technical Data pamphlet entitled "Dow Experi
mental Hardener XD-8062," dated March 2, 1975. Some of the disclosed uses for
this curing agent are iin compositions based on epoxy resins similar to those used in
the present invention. These compositions exhibit acceptable flexibility and adhesion but require a relatively long cure time.
Therefore, there remains a need for an epoxy resin powder coating composition which cures rapidly, preferably in less than two minutes at commercially acceptable temperatures, and which has good adhesion, adhesion retention under cathodic pro- tection, and flexibility.
According to the present invention, there is provided a thermosetting powder coating composition which consists essentially of finely divided particles at least 90 percent by weight of which have a maximum dimension not exceeding 150 microns.
The particles are a blend of a composition of:
(A) 9-25 parts by weight of an epoxy resin of the formula
where n is sufficiently large to provide a resin having a Gardner-Holdt Viscosity of H-L measured at 40 percent polymer solids in diethylene glygol nXbutyl ether at 250C and having an epoxide equivalent weight of 575-700; (B) 0.9-3 parts by weight of an epoxy resin having the same general formula as (A) but having a value for n sufficiendy large to provide a resin having a Gardner
Holt Viscosity of K-P measured as above and having an epoxide equivalent weight of 660-810; (C) 20-38 parts by weight of an epoxy/epoxy novolac resin which is an epoxy resin of the formula of (A) cross-linked with an epoxy novolac resin of the formula
where n of the epoxy resin and m of the epoxy novolac resin have values sufficiently large to provide an epoxy/epoxy novolac resin having a Gardner-Holdt Viscosity of W-Z measured as in (A) and having an epoxide equivalent weight of 750--860; (D)0-25 parts by weight of an epoxy/epoxy novolac resin of the formula of (C) but having values for n and m sufficiently large to provide an epoxy/epoxy novolac resin having a Gardner-Holdt Viscosity of O--S measured as in (A) and having an epoxide equivalent weight of 500-575 wherein the parts by weight of components (C) and (D) total at least 34.
(E) 10--20 parts by weight of filler particles having a maximum dimension of 10 microns; and
(F) 18-25 parts by weight of a resinous curing agent consisting essentially of:
1. 68-81 parts by weight of a compound of the formula
where Ar
and x is a positive number sufficiently large to provide a compound with a weight average molecular weight of 1250-1600, as determined by Gel Permeation Chroma- tography based on a linear calibration curve obtained from narrow molecular weight polystyrene standards;
2. 17-30 parts by weight of bisphenol-A; and
3. 0.6-2.0 parts by weight of an alykylimidazole in Which the alkyl group contains 1-4 carbon atoms.
Preferably, the particles are a blend of: 11-12 parts by weight of the epoxy resin (A);
1 part by weight of the epoxy resin (B); 22-23 parts by weight of the epoxy/epoxy novolac resin (C); 22-23 parts by weight of the epoxy/epoxy novolac resin (D); 16-17 parts by weight of filler particles Q wherein the filler particles are silica,
barium sulfate, or a mixture of these; and 22-23 parts by weight of the resinous curing agent (F).
It has been found that the epoxy resin powder coating composition of this inven
tion unexpectedly eliminates the disadvantages of the prior art with respect to speed
of cure, flexibility, and adhesion retention. The desirable aspects of the prior art
coatings have been incorporated by the new composition to an unexpected degree.
The coating composition of this invention has a powder particle size such that
at least 90 percent by weight of the particles have a maximum dimension not exceeding 150 microns and preferably none has a maximum dimension exceeding 200 microns. It
is preferred that there be a maximum dimension of 10-120 micrbns and more pre
ferred that it be 40-100 microns.
About 9-25 parts by weight of the powder coating composition is an epoxy resin
which lis of the epichlororhydrinxbisphenol-A type, of the formula
where n is sufficiently large to provide a Gardner-Holdt Viscosity of H-L measured at 40 percent polymer solids in diethylene glycol n-butyl ether at 250C and the resin has an epoxide equivalent weight of 575-700. The epoxide equivalent weight is the weight in grams of epoxy resin that contains one gram equivalent of epoxide.
Preferably 10-15 parts by weight and most preferably about 11-12 parts by weight of this epoxy resin are used in the powder coating composition.
About 0.9-3 parts by weight of another epoxy resin is used in the composition.
This epoxy resin has the same general formula as the above resin and has a Gardner Holdt Viscosity, measured as above, of K-P and an epoxide equivalent weight of 660-810. Preferably, the weight ratio of this epoxy resin to the first epoxy resin is approximately 0.08/1 to 0.2/1.
About 20-38 parts by weight of an epoxy/epoxy novolac resin is used in the composition. This resin is an epichlorohydrin-bisphenol-A resin of the formula shown above modified with an epoxy novolac resin of the formula
where n of the epoxy resin and m of the epoxy novolac resin have values sufficiently large to provide an epoxy/epoxy novolac resin having a Gardner-Holdt Viscosity of W-Z, measured at 40 percent polymer solids in diethylene glycol n-butyl ether at 25 0C and having an epoxide equivalent weight of 750-860. Preferably, 22-30 parts by weight of this resin is used.
Epoxy/epoxy novolac resins are formed by cross Plinking an epichlorohydrin-is- phenol-A resin with an epoxy novolac resin. It is believed that the modification is either direct crosslinking of the two resins or indirect crosslinking through reaction of both resins with bisphenol-A.
By varying the ratio of epichlorohydrin-bisphenol-A epoxy to epoxy novolac, the viscosity and epoxide equivalent weight can be varied and epoxy/epoxy novolac resins of different reactivity can be provided.
Optionally, up to 25 parts by weight of an epoxy/epoxy novolac of the same formula as above can be used in the composition. This resin has a Gardner-Holdt
Viscosity of O--S, measured as above, and an epoxide equivalent weight of 500-575.
Preferably this resin is present in the amount of 20-25 parts by weight, and more preferably 22-23 parts by weight, but the parts by weight of both epoxy/epoxy novolac resins should total at elast 34.
To improve abrasion resistance of the coating and to relieve shrinking forces which can occur during curing, the composition contains 10-20 parts by weight of filler particles having a maximum dimension of 10 microns. Conventional particulate fillers which can be used include silica, barium sulfate, calcium carbonate, aluminum silicate and mica. Preferred fillers are silica, barium sulfate, or mixtures of these. A suitable silica filler, for example, is commercially available under the trademark Min-U-SilQ > 5 registered to Pennsylvania Glass Sand Company.
When the composition is used to coat ribbed reinforcing bars or other sharp-edged articles, more uniform edge covering is attained when up to 3 percent by weight, based on the weight of the composition, of fumed silica is added. This is a very fine, amorphous silica formed from silica spheres having an average diameter of 714 millimicrons and having large surface area, 200--400 square meters per gram. Such a substance is commercially available from Cabot Corporation as Cab-O-Si.
A curing agent in the amount of 18-25 parts, preferably 21 to 25 parts, by weight is used in the composition. The agent is resinous in nature and contains:
1. 68-81 parts by weight of a compound of the formula
where Ar
and x is a positive number sufficiently large to provide a compound with a weight
average molecular weight of 1250--1600, as determined by Gel Permeation Chromo to,graphy (GPC) based on a linear calibration curve obtained from narrow molecular weight polystyrene standards;
2. 17-30 parts by weight of bisphenol-A; and
3. 0.6-2.0 parts by weight of an alkylimidazole in which the alkyl group contains
1-4 carbon atoms. Preferably, the alkyl group is methyl.
With respect to the first component o the curing agent it is preferred for a more flexible coating that the average molecular weight of this component be increased within its range as the parts by weight of the component used in the curing agent composition is increased.
The composition can be pigmented or unpigmented but is usually pigmented and contains a pigment to binder ratio of 3/100 to 30/100. Any conventional inorganic, organic, or filler pigments can be used. Examples of the pigments that can be used in the composition are: metallic oxides such as titanium dioxide, zinc oxide, iron oxide, or chrome oxide; metallic powders; metal hydroxides; sulfides; sulfates; and other filler pigments.
Flow control agents can be added to the powder coating composition in amounts up to 1.0 percent by weight based on the weight of the composition. Typical flow control agents are poly (alkyl acrylates) where the alkyl group contains 2-8 carbon atoms. A suitable substance for this purpose is commercially available under the trademark ModaPlow registered to Monsanto Corporation.
One method for forming the powder coating composition of this invention is to blend the components together and then to pass the mixture through a conventional
extruder. The extrudate can then be reduced to a powder using conventional grinding
equipment. After grinding, the powder is passed through a sieve to remove large
particles. Preferably, a sieve which eliminates particles ob maximum dimension greater
than 150 microns is used but 40-55 percent by weight of the powder should have a
maximum dimension not exceeding 44 microns.
The powder thus formed has the properties of rapid cure and good shelf-like to a
degree unexpected from the components involved. One particularly preferred composi
tion, described in Example 1, is found to cure in 90 seconds at 2320C. The same
cure rate is observed after the powder has been in storage for 4 weeks at 400C.
In the prior art, use of epoxy resins and curing agents substantially similar to
those used in the present invention produced powder coating compositions which
required cure times, at commercially acceptable temperatures, in excess of two minutes
to form smooth, flexible coatings. However, the present invention combines the components to produce synergistic results in a powder which not only cures in under two minutes but which also forms coatings which are adhesive, flexible, and smooth and even.
By comparison, an epoxy resin powder coating composition, shown in the Dow
Chemical Company Technical Data pamphlet entitled "Dow Experimental Hardener XD-8062" (page 8, Table III), March 2, 1975, is reported to require 3-5 minutes to cure at 2320,C. The composition shewn in this reference contains two epoxy/epoxy novolac resins and a curing agent substantially similar to components which partially comprise the composition of the present invention. While the coating formed by the composition is adhesive and impact resistant, it requires a longer cure time and exhibits less flexibility.
By way of further comparison, in the same reference there is shown (page 6,
Table II, Column 2) an epoxy resin powder coating composition containing two epoxy resins which, with others, are used in the present invention. This composition is cured by a curing agent substantially similar to that used in the present invention. This reference composition exhibits acceptable film properties but requires 15 minutes to cure at 2000C.
It has been found that the composition of the present invention combines these epoxy and epoxy/epoxy novolac resins with a curing agent to produce a new powder coating composition exhibiting unexpected properties. The film properties equal or surpass in quality those exhibited by the compositions of the above reference and these properties are attained with cures of less than two minutes at commercially acceptable temperatures.
It has also been found that coatings formed from the compositions of this invention have excellent resistance to adhesion loss under cathodic protection. A procedure used to test this resistance is one in which a metal panel is coated, as described below, with the powder coating composition. A hole 3 mm. in diameter is drilled through the coating and part way into the panel. A piece of 10-cm diameter plastic pipe is adhesively bonded to the coating to provide a nuid-tight container with the hole at the center of the flat base of this container. The container is filled with a solution of 5% NaCI in water. A platinum wire is placed in the solution and a direct current potential of 6 volts is applied continuously between the wire and the metal panel, which acts as the cathode in this circuit. After 30 days, the voltage source is disconnected, the solution is poured off, and any disbonded coating is scraped away with a sharp knife, leaving an uncoated circle, the diameter of which is measured. Prior art pipe coatings which are used commercially leave an uncoated circle of 2090 mm. diameter when subjected to this test. A preferred composition of the present invention leaves an uncoated circle of only 11-22 mm. diameter when subjected to this test.
The powder coating composition of this invention can be applied to a metal substrate by electrostatic spraying techniques or by using a fluidized bed which can be electrostatic. The preferable method is electrostatic spraying in which a voltage of 20-100 kilovolts is applied to the spray gun. The composition can be applied either in one pass or in several passes to provide variable thicknesses, after cure, of 0.2-0.5 mm, depending on the desired end-use of the coated article. Some pipes, for example, which are to be buried underground, require a coating thickness of approximately 0.4 mm.
The article to be coated can, optionally, be heated to any temperature up to approximately 2700C prior to the application of the powder. Preheating the article provides berated powder deposition and allows a more uniform coating.
After the application of the powder, the coated article is heated at 2000--2800C for 1-2 minutes to fuse and to cure the powder particles into a substantially continuous uniform coating. Tlle preferred temperature range is 2300--2530C when the alkylimidazole content of the curing agent is 1-1.4 weight percent. Curing temperatures above 253 0C can sometimes produce a brittle coating. When the weight per centage of alykylimidazole in the curing agent exceeds 1.6, curing temperatures above 2100C can sometimes produce a coating with poor appearance.
The composition of the invention can be applied directly to a metal surface, although for some end-uses a primer can be used. It is preferable that the surface to be coated be first cleaned by, for example, grinding or grit blasting.
The following examples illustrate the invention. In the examples, the components will be referred to according to the following numbering system:
(1) Epoxy resin having the formula
where n is sufficiently large to provide a Gardner-Holdt Viscosity of H-L measured at 40% polymer solids in diethylene glycol n-butyl ether at 250C and having an epoxide equivalent weight of 575-700 (2) Epoxy resin of the above formula but having a value for n such that there is provided a Gardner Holdt Viscosity, measured as above, of K-P and an epoxide equivalent weight of 660--810.
(3) Epoxy/epoxy novolac resin which is an epoxy resin of the formula of (1) modified with an epoxy novolac resin of the formula
where n of the epoxy resin and m of the epoxy novolac resin have values sufficiently large to provide an epoxy/epoxy novolac resin having a Gardner-Holdt Viscosity of W-Z, measured as in (1) and an epoxide equivalent weight of 750--860.
(4) Epoxy/epoxy novolac resin of the formula of (3) but having values for n and m sufficiently large to provide a Gardner-Holdt Viscosity of O--S, measured as in (1) and an epoxide equivalent weight d 500-575 (5) Silica particles, maximum dimension 10 microns
(6) Curing agent which is a combqination of: a. 70 parts by weight of a resin of the formula
where Ar
and x is approximately 3.8 corresponding to a weight average GPC molecular
weight ob 1312 based on a linear calibration curve obtained from narrow molecular
weight polystyrene standards;
b. 30 parts by weight bisphenol-A; and
c. 1.3 parts by weight of 2-methylimidazole
(7) Titanium dioxide pigment
(8) Red Iron oxide pigment
(9) ModaFlow' EXAMPLE 1.
The following components are blended together: Component Parts by weight
1 11.3
2 1.0
3 22.8
4 22.8
5 16.6
6 22.4
7 0.4
8 2.8
9 0.05
The above blend is charged into a melt extruder and extruded at 880--940C.
The extrudate is then broken into chips and charged into a grinding mill where it is ground to a fine powder. The powder is then passed through a sieve which removes particles of maximum dimension greater than 150 microns.
The powder thus formulated can be stored for four weeks at 400C without appreciable loss of ability to cure rapidly or to form a smooth film.
Before application of the powder, a 3-mm. thick grit blasted steel panel to be coated in this example is heated to 253 0C. The powder is then applied by Ransburg electrostatic powder guns. The guns use 60 volts of the electricity to charge the powder particles and 60 pounds per square inch air pressure to propel the particles which are fed to each gun, from a fluidized bed reservoir, by an air stream. The panel is then heated for 90 seconds at 2320C. The resulting film is smooth and even and is free from popping and cratering. The film thickness is approximately 0.3 mm.
The coated steel panel has a frontal impact resistance of 160 inch-pounds using a Gardner impact tester No. 16-1120. No visible cracks in the coating appear when the panel is bent 1800 about a conically shaped mandrel varying from 1/8 inch to 1i winches diameter over an 8-inch length. After repeated tests for adhesion loss under cathodic protection, as described above, the circular coating areas which delaminate have diameters which range from 11-22 mm., indicating little adhesion loss.
EXAMPLE 2.
The following components are blended together:
Component Parts by weight
1 23.0
2 2.0
3 34.7
5 16.6
6 20.6
7 0.4
8 2.8
9 0.1
The powder is formed as in Example 1. The powder of this example also can
be stored for 4 weeks at 400C without appreciable loss of ability to cure rapidly or to
form a smooth film.
The powder is applied to a panel as in Example 1. The panel is then heated,
for purposes of curing, for 2 minutes at 2320C. If this particular composition is cured
at a higher temperature, a brittle film can result.
The coated steel panel of this example has a frontal impact resistance ob 160 inch
pounds using a Gardner impact tester No. 16-1120. No visible cracks in the coating
appear when the panel is bent 1800 around a conically shaped mandrel varying from
1/8 inch to 1+ inches diameter over an 8-inch length.
EXAMPLE 3.
The composition, powder formation and application procedures of Example 1
are used to coat a 1-2--foot length of 112Anch inside diameter steel pipe. The edges of
the pipe are uniformly coated and the coating along the pipe walls is substantially
uniform, smooth and even, and free from popping and cratering.
WHAT WE CLAIM IS:
1. A powder coating composition which consists essentially of finely divided particles at least 90 percent by weight of which have a maximum dimension not exceeding 150 microns wherein the particles are a blend of:
(A) 9-25 parts by weight of an epoxy resin of the formula
**WARNING** end of DESC field may overlap start of CLMS **.
Claims (11)
1 23.0
2 2.0
3 34.7
5 16.6
6 20.6
7 0.4
8 2.8
9 0.1
The powder is formed as in Example 1. The powder of this example also can
be stored for 4 weeks at 400C without appreciable loss of ability to cure rapidly or to
form a smooth film.
The powder is applied to a panel as in Example 1. The panel is then heated,
for purposes of curing, for 2 minutes at 2320C. If this particular composition is cured
at a higher temperature, a brittle film can result.
The coated steel panel of this example has a frontal impact resistance ob 160 inch
pounds using a Gardner impact tester No. 16-1120. No visible cracks in the coating
appear when the panel is bent 1800 around a conically shaped mandrel varying from
1/8 inch to 1+ inches diameter over an 8-inch length.
EXAMPLE 3.
The composition, powder formation and application procedures of Example 1
are used to coat a 1-2--foot length of 112Anch inside diameter steel pipe. The edges of
the pipe are uniformly coated and the coating along the pipe walls is substantially
uniform, smooth and even, and free from popping and cratering.
WHAT WE CLAIM IS:
1. A powder coating composition which consists essentially of finely divided particles at least 90 percent by weight of which have a maximum dimension not exceeding 150 microns wherein the particles are a blend of:
(A) 9-25 parts by weight of an epoxy resin of the formula
where n is sufficiently large to provide a resin having a Gardner-Holdt Viscosity of H-L measured to 40 percent polymer solids in diethylene glycol n-butyl ether at 250C and having an epoxide equivalent weight of 575-700; (B) 0.9-3 parts by weight of an epoxy resin having the same general formula as (A) but having a value for n sufficiently large to provide a resin having a Gardner
Holdt Viscosity of K-P measured as above and having an epoxide equivalent weight of 660-810; (C) 20-38 parts by weight of an epoxy/epoxy novolac resin which is an epoxy resin d the formula d (A) crosslinked with an epoxy novolac resin of the formula
where n of the epoxy resin and m of the epoxy novolac resin have values sufficiently
large to provide an epoxy/epoxy novolac resin having a Gardner-Holdt Viscosity of W-Z measured as lin (A) and having an epoxide equivalent weight of 750-860; (D) 0-25 ,parts by weight of an epoxy/epoxy novolac resin of the formula of (C) but having values for n and m sufficiently large to provide an epoxy/epoxy novolac resin having a Gardner-Holdt Viscosity of O--S measured as in (A) and having an epoxide equivalent weight of 500-575, wherein the parts by weight of components (C) and (D) total at least 34; (E) 10-20 parts by weight of filler particles having a maximum dimension of 10 microns; and
(F) 18-25 parts by weight of a resinous curing agent consisting essentially of:
(1) 68-81 parts by weight of a compound of the formula
where Ar
and where x is a positive number sufficiently large to provide a compound with
a weight average molecular weight of 1250-1600, as determined by Gel Permea
tion Chromatography based on a linear calibration curve obtained from narrow
molecular weight polystyrene standards; (2)17-30 parts by weight of bisphenol-A; and
(3) 0.6-2.0 parts by weight of an alkylimidazole in which the alkyl group contains 1-4 carbon atoms.
2. The powder coating composition of Claim 1 containing pigment in a pigment to binder ratio by weight of 3/100 to 30/100.
3. The powder coating composition of Claim 1 or 2 containing up to 1 percent by weight, based on the weight of the composition of a poly(alkyl acrylate) as a flow control agent.
4. The powder coating composition of Claim 1, 2 or 3 containing up to 3 percent by weight, based on the weight of the composition, of fumed silica.
5. The powder coating composition of Claim 1, 2, 3 or 4 in which the filler particles are silica, barium sulfate, or a mixture of these.
6. The powder coating composition of any one of the preceding claims having: 10-15 parts by weight of Component A; 22-30 parts by weight of Component C; 20-25 parts by weight of Component D; 21-25 parts by weight of Component F.
7. A powder coating composition according to any one of the preceding claims wherein the particles are a blend of: 11---12 parts by weight of the epoxy resin (A);
1 part by weight of the epoxy resin (B); 22-23 parts by weight of the epoxy/epoxy novolac resin (C); 22723 parts by weight of the epoxy/epoxy novolac resin (D); 16---17 parts by weight of filler particles (E) wherein the filler particles are
silica, barium sulfate, or a mixture of these; and 22-23 parts by weight of the resinous curing agent (F).
8. The powder coating composition of any one of the preceding claims in which:
component 1 of the curing agent is present in the amount of 70 parts by
weight and has a molecular weight of 1312;
component 2 of the curing agent is present in the amount of 30 parts by
weight; and
component 3 of the curing agent is 2-methylimidazole.
9. A powder coating composition according to Claim 1 substantially as hereinbefore described.
10. A powder coating composition according to Claim 1 substantially as hereinbefore described in any one of the Examples.
11. An article coated with a composition according to any one of the preceding claims.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US80705877A | 1977-06-16 | 1977-06-16 | |
| US05/877,997 US4122060A (en) | 1977-06-16 | 1978-02-15 | Epoxy resin powder coating composition |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB1583539A true GB1583539A (en) | 1981-01-28 |
Family
ID=27122964
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB20448/78A Expired GB1583539A (en) | 1977-06-16 | 1978-05-18 | Epoxy resin powder coating composition |
Country Status (7)
| Country | Link |
|---|---|
| JP (1) | JPS547437A (en) |
| CA (1) | CA1103387A (en) |
| DE (1) | DE2826556A1 (en) |
| ES (1) | ES470830A1 (en) |
| FR (1) | FR2394590A1 (en) |
| GB (1) | GB1583539A (en) |
| NL (1) | NL7806481A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0916709A2 (en) * | 1997-11-04 | 1999-05-19 | Morton International, Inc. | A one-component, low temperature curable coating powder |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4777084A (en) * | 1987-10-08 | 1988-10-11 | Minnesota Mining And Manufacturing Company | Phenolic-modified epoxy adhesive including the reaction product of bisphenol A and the monoglycidyl ether of bisphenol A |
| US4868059A (en) * | 1987-11-16 | 1989-09-19 | The Dow Chemical Company | Curable composition containing a difunctional epoxy resin, a polyfunctional epoxy resin, a difunctional phenol and a polyfunctional phenol |
| JPH02227470A (en) * | 1989-02-28 | 1990-09-10 | Somar Corp | Epoxy resin powder coating composition |
| DE4322437C1 (en) * | 1993-07-06 | 1995-03-30 | Basf Lacke & Farben | Powder coating, process for the external coating of metal pipes and use of the powder coating for single-layer external coating of metal pipes |
| JP6342696B2 (en) * | 2014-04-23 | 2018-06-13 | ソマール株式会社 | Powder coating material and method for producing coating film using powder coating material |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2050777A5 (en) * | 1969-06-24 | 1971-04-02 | Alsthom | |
| US3882064A (en) * | 1973-12-27 | 1975-05-06 | Du Pont | Epoxy resin powder coating composition |
| US4009223A (en) * | 1974-05-08 | 1977-02-22 | Westinghouse Electric Corporation | Thin film electrostatic epoxy coating powder |
-
1978
- 1978-05-18 GB GB20448/78A patent/GB1583539A/en not_active Expired
- 1978-06-14 CA CA305,419A patent/CA1103387A/en not_active Expired
- 1978-06-15 NL NL7806481A patent/NL7806481A/en not_active Application Discontinuation
- 1978-06-15 ES ES470830A patent/ES470830A1/en not_active Expired
- 1978-06-16 FR FR7818109A patent/FR2394590A1/en not_active Withdrawn
- 1978-06-16 JP JP7368278A patent/JPS547437A/en active Pending
- 1978-06-16 DE DE19782826556 patent/DE2826556A1/en not_active Withdrawn
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0916709A2 (en) * | 1997-11-04 | 1999-05-19 | Morton International, Inc. | A one-component, low temperature curable coating powder |
| EP0916709A3 (en) * | 1997-11-04 | 2000-11-08 | Morton International, Inc. | A one-component, low temperature curable coating powder |
Also Published As
| Publication number | Publication date |
|---|---|
| CA1103387A (en) | 1981-06-16 |
| NL7806481A (en) | 1978-12-19 |
| FR2394590A1 (en) | 1979-01-12 |
| DE2826556A1 (en) | 1979-01-04 |
| ES470830A1 (en) | 1979-09-16 |
| JPS547437A (en) | 1979-01-20 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PS | Patent sealed | ||
| PCNP | Patent ceased through non-payment of renewal fee |