CA1226123A - Conductive coatings - Google Patents
Conductive coatingsInfo
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- CA1226123A CA1226123A CA000471237A CA471237A CA1226123A CA 1226123 A CA1226123 A CA 1226123A CA 000471237 A CA000471237 A CA 000471237A CA 471237 A CA471237 A CA 471237A CA 1226123 A CA1226123 A CA 1226123A
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Abstract
CONDUCTIVE COATINGS
ABSTRACT
A conductive pretreatment solution is disclosed which renders dried wood electrostatically coatable through several coatings while minimizing contamina-tion of the topcoat. The pretreatment solution com-prises a volatile liquid carrier selected from water and organic solvents, the carrier having dissolved therein, per 100 parts by volume of total solution, (1) from 0.2 to 3 parts by volume of an organic quaternary ammonium compound having a molecular weight below about 1000, (2) from 0.2 to 10 parts by volume of a low volatile liquid polyol having a molecular weight below about 400, and (3) from 0.1 to 3 parts by weight of an inorganic ionizable salt having a capacity to absorb moisture, especially chlorides of a cation selected from the group consisting of ammonium, magnesium and calcium.
ABSTRACT
A conductive pretreatment solution is disclosed which renders dried wood electrostatically coatable through several coatings while minimizing contamina-tion of the topcoat. The pretreatment solution com-prises a volatile liquid carrier selected from water and organic solvents, the carrier having dissolved therein, per 100 parts by volume of total solution, (1) from 0.2 to 3 parts by volume of an organic quaternary ammonium compound having a molecular weight below about 1000, (2) from 0.2 to 10 parts by volume of a low volatile liquid polyol having a molecular weight below about 400, and (3) from 0.1 to 3 parts by weight of an inorganic ionizable salt having a capacity to absorb moisture, especially chlorides of a cation selected from the group consisting of ammonium, magnesium and calcium.
Description
~L%261;~3 CONDUCTIVE Cowlings TECHNICAL FIELD
__ This invention relates to compositions adapted to be applied to the surface of insulators, and especially dried wood surfaces, to render the same durably conduct live, especially after exposure to moisture in a high humidity chamber.
BACKGROUND ART
Electrostatic spray processes deposit coating mate-fiats with great efficiency, thus minimizing waste and pollution, but they normally demand that the base to be coated be conductive so that the charge can be carried away to a ground. This is easily carried out when the substrate is conductive, but dried wood and plastics 15 are insulators, so the charge builds up on the substrate being coated to repel the charged coating particles.
This destroys the effectiveness of the electrocuting process.
It is known to pretreat the surface of the insulate 20 or to render it conductive, and aqueous and non aqueous solutions containing ionizable compounds, both organic and inorganic, have been used for this purpose. As a result, electrostatic spray processes are now commonly used to coat wood and plastic surfaces.
It is desired to maximize the effectiveness of the electrostatic coating of insulators, and especially wood, where a plurality of coatings must be applied in order to provide the desired finish. The difficulty is that the coatings are of insulating character, and it is de-I sired that the initial pretreatment of the substrate continue to provide a capacity to receive charged spray particles after several coatings have been applied.
To achieve this result, it is known to expose the pretreated and coated objects to high tumidity in order to enhance the conductivity of the pretreatment, but 1~26~:3 even this expedient fails after a few coatings. Unfortu-namely, the normal finishing of wood for furniture use involves many coatings, so superior pretreatment are needed to extend the number of coatings which can be of-lively received by the pretreated substrate following humidification in known fashion).
It is also known that conductive pretreatment ad-tersely effect wood. Thus, and while aqueous pretreat-mints are broadly useful herein, they can injure wood and solvent solutions are preferred. Agents which damage or discolor the wood (either immediately or with -time) or which interfere with adhesion of the coatings to one another or with the capacity of the coating and the substrate to resist changing environments, are preferably I avoided.
Also, the conductive agents are sensitive to moisture, and if these are present in the finished coating, they can render it sensitive to moisture.
This causes the coating to blush (whiten) in high 20 humidity atmosphere at room or lower temperature. As will be evident, this adverse result must also be avoided.
Disclosure of Invention In this invention, a conductive pretreatment 25 solution comprises a volatile liquid carrier selected from. water and organic solvents. This carrier has dissolved therein, per 100 parts by vole of total solution, I from 0.2 to 3 parts by volume of an organic qua ternary armmonium compound having a molecular 30 weight below about 1000, (2) from 0.2 to 10 parts my volume of a low volatile liquid polyol having a molecular weight below about 400, and (3) from 0.1 to 3 parts by weight of an inorganic ionizable salt having a capacity to absorb moisture. Chloride salts 35 are preferred, especially chloride salts of a cation selected from the group consisting of ammonium, magnesium and calcium. Ammonium salts yield the best ~L2263L23 dye compatibility.
The volatile liquid carrier is preferably constitu-ted by organic solvent together with from 0.1 to parts by volume of water per 100 parts of total volume.
The qua ternary compound preferably has a molecular weight below about 400, and the polyol preferably has a molecular weight below about 200 and contains at least three hydroxyl groups per molecule. Bouncily trim ethyl ammonium chloride and glycerine are especially preferred.
10 Based on the same 100 parts by volume of total solution, it is preferred to employ OOZE parts by volume of the qua ternary compound, from 1.0-3.0 parts by volume of the polyol, and from 0.~-1.5 parts by weight of the salt, preferably the chloride salt.
Lastly, and since application to dried wood is particularly contemplated, it is desirable to haze at least 20% ox the volatile solvents constituted by alcoholic solvents, such as methanol. Also, it is sometimes helpful to have from 5-15% of thy volatile 20 solvents constituted my ethics diethylene glycol which will constitute part of Tao alcoholic solvent.
It will be observed that the solutions used herein contain a combination of three active components. Len any one ox the three is omitted, the increased conduct 25 tivity which is provided (or which is enhanced by humidity exposure) is quickly lost. The increased conductivity provided herein is more durable.
It will also be observed that the solutions used herein are dilute solutions. As a result, after the 30 wood surface has been jetted and dried to remove vote-tile solvent, excessive amounts of the active agents are not applied. These would bleed through the various applied coatings and contaminate the topcoat, thereby impairing its resistance to moisture.
An important aspect of this invention is the enhanced capacity of the conductive pretreatment of 12~6~L2,3 this invention to enable electrostatic deposition even when conductivity measurements of the coaled surface being electrocuted with the desired topcoat are so low as to be normally regarded as no-t electrostatically spray able. It is this combination of electrical visit-islet ( to the charged spray particles being attracted to the grounded target) and chemical invisibility (which prevents contamination of the topcoat) which uniquely characterizes this invention and enables 10 electrode position to take place without rendering the usual nitrocellulose topcoats for wood unduly sensitive to moisture. This defect leads to blushing in humid atmospheres.
it may be helpful to understand something about 15 wood and electrostatic coating. Charged spray particles are attracted to a grounded target by virtue of the difference between the charge on the particles and the charge on the target. If the target is an insulator, the charge builds up on that target because it cannot 20 get to the ground, and now the target and the spray particles have a like charge and the spray particles are repelled. Wood must be dried to about 6-8% moisture to be able to withstand the changes in humidity which are normally encountered on any continental land mass.
25 At this low moisture content, wood is too resistive to be electrostatically sprayed. This is why the wood must be wetted with an agent which will improve its conductivity, and why this agent is preferably not water, though a small amount of water is helpful in 30 this invention. Of course, if water is used as the carrier, one can dry the wood to remove as much of the added moisture as one wishes. also, the pretreatment of this invention, while of especial importance to the treatment of wood, can be used for the treatment ox 35 other insulating surfaces which are not sensitive to water.
~2;~6123 Humidification is an optional, albeit a desirable, feature. This is because the pretreatment enhances conductivity without humidification, so one might accept a lesser conductivity in some coating sequences. Also, some atmospheres are more humid than others, so sepal rate humidification may not be needed, as on a hot and Harold summer day.
Any organic qua ternary ammonium compound having a molecular weight below about 1000 can be used herein.
10 While higher molecular weight compounds are suggested as useful in the prior art, present experience has demonstrated that these are not satisfactory herein.
The qua ternary ammonium compound may have a single quit-ernized nitrogen atom, or it may have more than one, 15 e.g., doctrinaire ammonium compounds are available and are useful herein. N, N, N, trim ethyl bouncily ammonium chloride is particularly preferred and will be used herein as illustrative (the it, I, N, identification is understood and normally omitted). The use of organic 20 qua ternary ammonium compounds for the subject purpose is discussed at length in Spiller et at. U. S. Pat No.
3,236,679, and any of the many qua ternary ammoni-lm compounds named therein may ye used herein so long as the required low molecular weight is present. Thus, 25 Spiller et at. indicate a preference for qua ternary and doctrinaire ammonium chlorides having a carbon to nitrogen ratio ox from loll to 30:1, and this is sails-factory herein so long as only low molecular weight materials are selected.
While glycerine is the preferred low volatile liquid polyol, other similar materials such as in-methylol propane, diethylene glycol, dipropylene glycol, and triethylene glycol are also useful. Higher lung-tonal polyols. like sorbitol, are also useful. Waxy 35 material, like high molecular weight polyethylene glycols create problems and are nut useful.
22~123 Example L (Stalin) Parts by V m _ 100 methanol containing 0.75 weight percent of a dye colorant
__ This invention relates to compositions adapted to be applied to the surface of insulators, and especially dried wood surfaces, to render the same durably conduct live, especially after exposure to moisture in a high humidity chamber.
BACKGROUND ART
Electrostatic spray processes deposit coating mate-fiats with great efficiency, thus minimizing waste and pollution, but they normally demand that the base to be coated be conductive so that the charge can be carried away to a ground. This is easily carried out when the substrate is conductive, but dried wood and plastics 15 are insulators, so the charge builds up on the substrate being coated to repel the charged coating particles.
This destroys the effectiveness of the electrocuting process.
It is known to pretreat the surface of the insulate 20 or to render it conductive, and aqueous and non aqueous solutions containing ionizable compounds, both organic and inorganic, have been used for this purpose. As a result, electrostatic spray processes are now commonly used to coat wood and plastic surfaces.
It is desired to maximize the effectiveness of the electrostatic coating of insulators, and especially wood, where a plurality of coatings must be applied in order to provide the desired finish. The difficulty is that the coatings are of insulating character, and it is de-I sired that the initial pretreatment of the substrate continue to provide a capacity to receive charged spray particles after several coatings have been applied.
To achieve this result, it is known to expose the pretreated and coated objects to high tumidity in order to enhance the conductivity of the pretreatment, but 1~26~:3 even this expedient fails after a few coatings. Unfortu-namely, the normal finishing of wood for furniture use involves many coatings, so superior pretreatment are needed to extend the number of coatings which can be of-lively received by the pretreated substrate following humidification in known fashion).
It is also known that conductive pretreatment ad-tersely effect wood. Thus, and while aqueous pretreat-mints are broadly useful herein, they can injure wood and solvent solutions are preferred. Agents which damage or discolor the wood (either immediately or with -time) or which interfere with adhesion of the coatings to one another or with the capacity of the coating and the substrate to resist changing environments, are preferably I avoided.
Also, the conductive agents are sensitive to moisture, and if these are present in the finished coating, they can render it sensitive to moisture.
This causes the coating to blush (whiten) in high 20 humidity atmosphere at room or lower temperature. As will be evident, this adverse result must also be avoided.
Disclosure of Invention In this invention, a conductive pretreatment 25 solution comprises a volatile liquid carrier selected from. water and organic solvents. This carrier has dissolved therein, per 100 parts by vole of total solution, I from 0.2 to 3 parts by volume of an organic qua ternary armmonium compound having a molecular 30 weight below about 1000, (2) from 0.2 to 10 parts my volume of a low volatile liquid polyol having a molecular weight below about 400, and (3) from 0.1 to 3 parts by weight of an inorganic ionizable salt having a capacity to absorb moisture. Chloride salts 35 are preferred, especially chloride salts of a cation selected from the group consisting of ammonium, magnesium and calcium. Ammonium salts yield the best ~L2263L23 dye compatibility.
The volatile liquid carrier is preferably constitu-ted by organic solvent together with from 0.1 to parts by volume of water per 100 parts of total volume.
The qua ternary compound preferably has a molecular weight below about 400, and the polyol preferably has a molecular weight below about 200 and contains at least three hydroxyl groups per molecule. Bouncily trim ethyl ammonium chloride and glycerine are especially preferred.
10 Based on the same 100 parts by volume of total solution, it is preferred to employ OOZE parts by volume of the qua ternary compound, from 1.0-3.0 parts by volume of the polyol, and from 0.~-1.5 parts by weight of the salt, preferably the chloride salt.
Lastly, and since application to dried wood is particularly contemplated, it is desirable to haze at least 20% ox the volatile solvents constituted by alcoholic solvents, such as methanol. Also, it is sometimes helpful to have from 5-15% of thy volatile 20 solvents constituted my ethics diethylene glycol which will constitute part of Tao alcoholic solvent.
It will be observed that the solutions used herein contain a combination of three active components. Len any one ox the three is omitted, the increased conduct 25 tivity which is provided (or which is enhanced by humidity exposure) is quickly lost. The increased conductivity provided herein is more durable.
It will also be observed that the solutions used herein are dilute solutions. As a result, after the 30 wood surface has been jetted and dried to remove vote-tile solvent, excessive amounts of the active agents are not applied. These would bleed through the various applied coatings and contaminate the topcoat, thereby impairing its resistance to moisture.
An important aspect of this invention is the enhanced capacity of the conductive pretreatment of 12~6~L2,3 this invention to enable electrostatic deposition even when conductivity measurements of the coaled surface being electrocuted with the desired topcoat are so low as to be normally regarded as no-t electrostatically spray able. It is this combination of electrical visit-islet ( to the charged spray particles being attracted to the grounded target) and chemical invisibility (which prevents contamination of the topcoat) which uniquely characterizes this invention and enables 10 electrode position to take place without rendering the usual nitrocellulose topcoats for wood unduly sensitive to moisture. This defect leads to blushing in humid atmospheres.
it may be helpful to understand something about 15 wood and electrostatic coating. Charged spray particles are attracted to a grounded target by virtue of the difference between the charge on the particles and the charge on the target. If the target is an insulator, the charge builds up on that target because it cannot 20 get to the ground, and now the target and the spray particles have a like charge and the spray particles are repelled. Wood must be dried to about 6-8% moisture to be able to withstand the changes in humidity which are normally encountered on any continental land mass.
25 At this low moisture content, wood is too resistive to be electrostatically sprayed. This is why the wood must be wetted with an agent which will improve its conductivity, and why this agent is preferably not water, though a small amount of water is helpful in 30 this invention. Of course, if water is used as the carrier, one can dry the wood to remove as much of the added moisture as one wishes. also, the pretreatment of this invention, while of especial importance to the treatment of wood, can be used for the treatment ox 35 other insulating surfaces which are not sensitive to water.
~2;~6123 Humidification is an optional, albeit a desirable, feature. This is because the pretreatment enhances conductivity without humidification, so one might accept a lesser conductivity in some coating sequences. Also, some atmospheres are more humid than others, so sepal rate humidification may not be needed, as on a hot and Harold summer day.
Any organic qua ternary ammonium compound having a molecular weight below about 1000 can be used herein.
10 While higher molecular weight compounds are suggested as useful in the prior art, present experience has demonstrated that these are not satisfactory herein.
The qua ternary ammonium compound may have a single quit-ernized nitrogen atom, or it may have more than one, 15 e.g., doctrinaire ammonium compounds are available and are useful herein. N, N, N, trim ethyl bouncily ammonium chloride is particularly preferred and will be used herein as illustrative (the it, I, N, identification is understood and normally omitted). The use of organic 20 qua ternary ammonium compounds for the subject purpose is discussed at length in Spiller et at. U. S. Pat No.
3,236,679, and any of the many qua ternary ammoni-lm compounds named therein may ye used herein so long as the required low molecular weight is present. Thus, 25 Spiller et at. indicate a preference for qua ternary and doctrinaire ammonium chlorides having a carbon to nitrogen ratio ox from loll to 30:1, and this is sails-factory herein so long as only low molecular weight materials are selected.
While glycerine is the preferred low volatile liquid polyol, other similar materials such as in-methylol propane, diethylene glycol, dipropylene glycol, and triethylene glycol are also useful. Higher lung-tonal polyols. like sorbitol, are also useful. Waxy 35 material, like high molecular weight polyethylene glycols create problems and are nut useful.
22~123 Example L (Stalin) Parts by V m _ 100 methanol containing 0.75 weight percent of a dye colorant
2 40% aqueous solution of NUN trim ethyl bouncily ammonium chloride 2 glycerine 1 [weight percent] calcium chloride (an hydrous) [commercial grade containing 94-97% calcium chloride]
The above are blended together with simple stirring for 5-10 minutes to dissolve the calcium chloride in the solution.
Example 2 (Pigmented Stain) Parts by Volume methanol methyl ethyl kitten 20 40 bottle acetate with 0.8 wt. JO pigments l 40% aqueous solution of N,N,NJ trim ethyl bouncily ammonium Sherwood 1 glycerine 0.5 weight percent] calcium chloride (same as in US Example 1) The above are mixed together as in example l.
Example 3 Pecan wood is dried to kiwi% moisture content and is wetted (by air spraying) with the stain of Example l.
30 Enough spray is aped so that the wood surface is wet to the eye, and then application is stopped. The wetted wood air dries in 15 minutes .
A wash coat is then electrostatically applied to wet the pretreated substrate. The wash coat is a clear 35 12% solids by eight nitrccellulose lacquer and is air dried or 30 minutes and is then scuff sanded.
~2~6123 A pigmented wiping stain consisting of 14'~ of alkyd resin by volume, 28% by weight of pigments, balance Variously solvent, is then electrostatically sprayed on, wiped clean, and then air dried for one hour.
A 16% solids by weight nitrocellulose lacquer sealer is then electrostatically sprayed on to wet the surface, air dried for 45 minutes and then scuff sanded.
A pigmented glaze stain consisting of 16% fatty triglyceride oil by volume, 22% pigments by weight, 10 balance mineral spirits, is then sprayed on to wet the surface, wiped clean, and air dried for 30 minutes.
Electrostatic spray may be used, but in this example a simple air spray was used.
The finishing operation is performed in this in-15 stance in two stages. First, a wet coat of a clear solids by weight nitrocellulose lacquer is applied by electrostatic spray and air dried for I minutes. After drying and humidification exposure (30 seconds at 93%
relative humidity at 55F.), little if any response is 20 shown on a Ransburg Spray ability Meter Number 236 (Ran-burg Electrocuting Corp., Indianapolis, Indiana).
This would normally indicate that electrostatic spraying could not be used, or not used effectively (the reading is in the range identified on the meter as "non-25 spray able").
Despite this, a topcoat of the same composition as the first finish was sprayed on using an electrostatic system in which an air spray is charged by passing the spray particles past electrodes charged to JO kilovolts.
30 The spray equipment is spaced from the target by a disk lance of 1 to 3 feet (varied during application because the target turns in front of the spray gun. A wet coat was applied and air dried for 2 hours. The electron static spray produced a good deposition efficiency show-35 in that the pretreatment was fully effective even though no surface conductivity had been detected by the spray ability meter, as previously noted.
. ,. . . .. , . . Jo , ~26~L23 Testing of the finished wood in humidity chambers to see it the presence of the pretreatment impaired blush resistance revealed no adverse effect.
The topcoat referred to in this example is as 5 follows:
Volume Percent - 1/4 second nitrocellulose 8.01 short oil length coconut alkyd h.02 urea-formaldehyde condensate 0.31 10 ductile phthalate 3.6 finely divided silica 0.17 bottle acetate 15.33 isobutyl isobutyrate 15.0 buttocks ethanol 2.33 15 isobutyl acetate 15.82 xylol 5.71 toluol 9.62 lacquer delineate 18.08 The lacquer delineate referred to in these examples 20 is as follows:
Parts by Volume lactol spirits (Union Chemical Company) 8.37 bottle alcohol .63 isopropyl alcohol 5-95 25 VAMP Naphtha ~.61 acetone .52 Similar results are obtained when the two vitro-cellulose lacquer finish coat are replaced by solvent solution finish coats containing all sorts of film-30 forming resins, such as cellulose acetate butyrate,alkyd urea varnishes, polyester topcoats, polyurethane topcoats, and vinyl rosin topcoats, as illustrated by solution copolymers of vinyl chloride and vinyl acetate.
In each instance, the electrostatically sprayed finish 35 coat is effectively electrode posited, jut the conduct live agents are sufficiently remote that the water nests-lance of the topcoats is not impaired.
The above are blended together with simple stirring for 5-10 minutes to dissolve the calcium chloride in the solution.
Example 2 (Pigmented Stain) Parts by Volume methanol methyl ethyl kitten 20 40 bottle acetate with 0.8 wt. JO pigments l 40% aqueous solution of N,N,NJ trim ethyl bouncily ammonium Sherwood 1 glycerine 0.5 weight percent] calcium chloride (same as in US Example 1) The above are mixed together as in example l.
Example 3 Pecan wood is dried to kiwi% moisture content and is wetted (by air spraying) with the stain of Example l.
30 Enough spray is aped so that the wood surface is wet to the eye, and then application is stopped. The wetted wood air dries in 15 minutes .
A wash coat is then electrostatically applied to wet the pretreated substrate. The wash coat is a clear 35 12% solids by eight nitrccellulose lacquer and is air dried or 30 minutes and is then scuff sanded.
~2~6123 A pigmented wiping stain consisting of 14'~ of alkyd resin by volume, 28% by weight of pigments, balance Variously solvent, is then electrostatically sprayed on, wiped clean, and then air dried for one hour.
A 16% solids by weight nitrocellulose lacquer sealer is then electrostatically sprayed on to wet the surface, air dried for 45 minutes and then scuff sanded.
A pigmented glaze stain consisting of 16% fatty triglyceride oil by volume, 22% pigments by weight, 10 balance mineral spirits, is then sprayed on to wet the surface, wiped clean, and air dried for 30 minutes.
Electrostatic spray may be used, but in this example a simple air spray was used.
The finishing operation is performed in this in-15 stance in two stages. First, a wet coat of a clear solids by weight nitrocellulose lacquer is applied by electrostatic spray and air dried for I minutes. After drying and humidification exposure (30 seconds at 93%
relative humidity at 55F.), little if any response is 20 shown on a Ransburg Spray ability Meter Number 236 (Ran-burg Electrocuting Corp., Indianapolis, Indiana).
This would normally indicate that electrostatic spraying could not be used, or not used effectively (the reading is in the range identified on the meter as "non-25 spray able").
Despite this, a topcoat of the same composition as the first finish was sprayed on using an electrostatic system in which an air spray is charged by passing the spray particles past electrodes charged to JO kilovolts.
30 The spray equipment is spaced from the target by a disk lance of 1 to 3 feet (varied during application because the target turns in front of the spray gun. A wet coat was applied and air dried for 2 hours. The electron static spray produced a good deposition efficiency show-35 in that the pretreatment was fully effective even though no surface conductivity had been detected by the spray ability meter, as previously noted.
. ,. . . .. , . . Jo , ~26~L23 Testing of the finished wood in humidity chambers to see it the presence of the pretreatment impaired blush resistance revealed no adverse effect.
The topcoat referred to in this example is as 5 follows:
Volume Percent - 1/4 second nitrocellulose 8.01 short oil length coconut alkyd h.02 urea-formaldehyde condensate 0.31 10 ductile phthalate 3.6 finely divided silica 0.17 bottle acetate 15.33 isobutyl isobutyrate 15.0 buttocks ethanol 2.33 15 isobutyl acetate 15.82 xylol 5.71 toluol 9.62 lacquer delineate 18.08 The lacquer delineate referred to in these examples 20 is as follows:
Parts by Volume lactol spirits (Union Chemical Company) 8.37 bottle alcohol .63 isopropyl alcohol 5-95 25 VAMP Naphtha ~.61 acetone .52 Similar results are obtained when the two vitro-cellulose lacquer finish coat are replaced by solvent solution finish coats containing all sorts of film-30 forming resins, such as cellulose acetate butyrate,alkyd urea varnishes, polyester topcoats, polyurethane topcoats, and vinyl rosin topcoats, as illustrated by solution copolymers of vinyl chloride and vinyl acetate.
In each instance, the electrostatically sprayed finish 35 coat is effectively electrode posited, jut the conduct live agents are sufficiently remote that the water nests-lance of the topcoats is not impaired.
Claims (23)
1. A conductive pretreatment solution comprising a volatile liquid carrier selected from water and organic solvents, said carrier having dissolved therein, per 100 parts by volume of total solution, (1) from 0.2 to 3 parts by volume of an organic quaternary ammonium compound having a molecular weight below about 1000, (2) from 0.2 to 10 parts by volume of a low volatile liquid polyol having a molecular weight below about 400, and (3) from 0.1 to 3 parts by weight of an inorganic ionizable salt having a capacity to absorb moisture.
2. A solution as recited in claim 1 in which said salt is a chloride salt.
3. A solution as recited in claim 2 in which said chloride salt is a salt of a cation selected from the group consisting of ammonium, magnesium and calcium.
4. solution as recited in claim 3 in which said solvent is constituted by organic solvents and from 0.1 to 4 parts water by volume per 100 parts total volume.
5. A solution as recited in claim 3 in which said quaternary compound has a molecullar weight below about 400, said polyol has a molecular weight below about 200 and contains at least three hydroxyl groups per molecule.
6. A solution as recited in claim 5 in which said quaternary compound is present in an amount of from 0.5-1.5 parts by volume, said polyol is present in an amount of from 1.0-3.0 parts by volume and said chloride salt is present in an amount of from 0.2-1.5 parts by weight.
7. A solution as recited in claim 3 in which said volatile solvents contain at least 20% of alcoholic solvent.
8. A solution as recited in claim 7 in which said alcoholic solvent comprises from 5-15% of 2-ethoxy di-ethylene glycol.
9. A solution as recited in claim 5 in which said polyol is glycerine.
10. A solution as recited in claim 5 in which said quaternary compound is benzyl trimethyl ammonium chloride.
11. A solution as recited in claim 5 in which said salt is calcium chloride.
12. A solution as recited in claim 5 in which said salt is ammonium chloride.
13. A solution as recited in claim 1 including a dye colorant so as to constitute a stain.
14. A solution as recited in claim 1 including a pigment so as to constitute a pigmented stain.
15. A method of coating dried wood comprising applying to the surface of said wood a conductive pre-treatment solution as defined in claim 1 and drying the same to remove said volatile carrier, then applying and drying at least one coating selected from washcoats, wiping stains, sealers, glazes, fillers, lacquer under-coats and lacquer enamels, and then electrostatically applying a solvent solution topcoat containing a film-forming resin, whereby said pretreatment is effective to assist electrostatic deposition of said topcoat without causing said topcoat to blush in humid atmospheres.
16. A method as recited in claim 15 in which said pretreated wood with said coatings thereon is sub-jected to a high humidity treatment shortly before the electrostatic deposition of said topcoat.
17. A method as recited in claim 16 in which said topcoat is electrodeposited while the surface of said pretreated and coated wood fails to show sufficient conductivity for electrostatic deposition when tested with electrodes placed at the surface thereof.
18. A method as recited in claim 15 in which said topcoat is a nitrocellulose lacquer.
19. A method as recited in claim 15 in which said topcoat is a cellulose acetate butyrate topcoat.
20. A method as recited in claim 15 in which said topcoat is an alkyd urea varnish.
21. A method as recited in claim 15 in which said topcoat is a polyester topcoat.
22. A method as recited in claim 15 in which said topcoat is a vinyl resin topcoat.
23. A method as recited in claim 15 in which said topcoat is a polyurethane topcoat.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000471237A CA1226123A (en) | 1984-12-31 | 1984-12-31 | Conductive coatings |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000471237A CA1226123A (en) | 1984-12-31 | 1984-12-31 | Conductive coatings |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1226123A true CA1226123A (en) | 1987-09-01 |
Family
ID=4129486
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000471237A Expired CA1226123A (en) | 1984-12-31 | 1984-12-31 | Conductive coatings |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1226123A (en) |
-
1984
- 1984-12-31 CA CA000471237A patent/CA1226123A/en not_active Expired
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