Method of improving the electrical conductivity of a molding article of resin, method of coating a molding article of resin, and coating composition

The invention provides a method of improving the electrical conductivity of a resin article and a method of coating the article, with high productivity and. without using an inorganic conductive substance-containing primer. The technology comprises coating the substrate with a coating composition essentially consisting of a film-forming component, a nitrogen-containing compound of general formula (1), and a solvent and subjecting the coated surface to corona discharge treatment. The resultant film with improved electrical conductivity is then electrostatically coated. EQU R.sup.1 --Y (1) wherein R.sup.1 represents an alkyl or alkenyl group of 5-21 carbon atoms; Y represents ##STR1## R.sup.2 and R.sup.3 may be the same or different and each represents an alkyl group of 1-4 carbon atoms; m represents 2-3; R.sup.4 represents --H or --CH.sub.3 ; A represents ##STR2## where n represents 1-5.

BACKGROUND OF THE INVENTION 
The present invention relates to a method of improving the electrical 
conductivity of a molding article of resin, a method of coating a molding 
article of resin, and a coating composition. 
The conventional method of coating a molding article of resin, for example, 
comprises coating an electrically conductive primer containing an 
inorganic conductive substance, e.g. conductive carbon black, graphite, or 
the like, on the surface of a polypropylene article to impart electrical 
conductivity to said surface and then carrying out electrostatic coating 
as described in JP-A-06165966. 
However, as pointed out in JP-A-06165966, an inorganic conductive substance 
such as carbon black or graphite must be added in a substantial amount in 
order that it may be evenly and thoroughly distributed in the surface of 
the polypropylene article. Therefore, the technology has drawbacks in 
terms of the dispersion stability of the electrically conductive substance 
and the cost of production. 
Recently disclosed is a method which comprises kneading a 
nitrogen-containing compound into the molding resin, molding the resultant 
composition, and subjecting the surface of the molding to low pressure 
plasma treatment (JP-A-07173308). 
However, because the plasma treatment must be a batch operation for low 
pressure, the method is not adaptable to continuous production and is poor 
in commercial productivity. 
SUMMARY OF THE INVENTION 
The present invention has for its object to overcome the above-mentioned 
disadvantages of the prior art and provide a method of improving the 
electrical conductivity of a molding article of resin and a method of 
coating a molding article of resin with good productivity and without a 
primer containing an inorganic electrically conductive substance, as well 
as a coating composition for use in carrying said methods into practice. 
The inventors of the present invention discovered that by coating a primer 
containing a specific nitrogen-containing compound on the surface of a 
molding article of resin and subjecting the treated surface to corona 
discharge treatment, the electrical conductivity of the surface can be 
improved to be suitable for electrostatic coating, thus overcoming the 
above disadvantages. 
The present invention is directed, in a first aspect, to a method of 
improving the electrical conductivity of a molding article of resin 
through enhancement of surface conductivity which comprises a first step 
(step 1) of coating a molding article of resin with a coating composition 
essentially consisting of a film-forming component, a nitrogen-containing 
compound of general formula (1), and a solvent and a second step (step 2) 
of subjecting the coated surface to corona discharge treatment. The 
present invention is directed, in a second aspect, to a method of coating 
a molding article of resin which comprises said steps 1 and 2 and a third 
step (step 3) of carrying out electrostatic coating on the corona 
discharge-treated surface obtained in said step 2. In a third aspect, the 
present invention is further directed to a coating composition comprising 
a film-forming component, a nitrogen-containing compound of general 
formula (1), and a solvent, which finds application in the above-mentioned 
methods. 
EQU R.sup.1 --Y (1) 
wherein R.sup.1 represents an alkyl or alkenyl group of 5-21 carbon atoms; 
Y represents 
##STR3## 
R.sup.2 and R.sup.3 may be the same or different and each represents an 
alkyl group of 1-4 carbon atoms; m represents 2-3; R.sup.4 represents --H 
or --CH.sub.3 ; A represents 
##STR4## 
where n represents 1-5. 
It is thought that in the accordance with methods of the present invention, 
owing to the corona discharge treatment, the presence of the 
nitrogen-containing compound of general formula (1) in a surface of the 
coating increases and the nitrogen-containing compound is partly 
quaternized. It is anticipated that these matters make to decrease the 
surface resistivity of the coating. So it is possible to get a molding 
article of resin improved in electrical conductivity. Further, together 
with a surface modifying effect of corona discharge, it is able to carry 
on electrostatic coating with high coating efficiency. 
Furthermore, because the corona discharge treatment is carried out at 
atmospheric pressure, continuous in-line production can be implemented, 
thus contributing to productivity. 
The present invention is particularly useful for the coating of materials 
which are intrinsically not suitable for electrostatic coating, such as 
polypropylene bumpers.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring to general formula (1), R.sup.1 represents an alkyl or alkenyl 
group of 5-21 carbon atoms, preferably a C.sub.7-17 alkyl or alkenyl 
group, and for still better results, a C.sub.9-15 alkyl or alkenyl group. 
The nitrogen-containing compound of general formula (1) includes a variety 
of amidoamines such as N,N-dimethylaminopropylhexanamide, 
N,N-diethylaminopropylhexanamide, N,N-diethylaminoethylhexanamide, 
N,N-dimethylaminopropyloctanamide, N,N-diethylaminopropyloctanamide, 
N,N-diethylaminoethyloctanamide, N,N-dibutylaminopropyloctanamide, 
N,N-dibutylaminoethyloctanamide, N,N-dimethylaminopropyldecanamide, 
N,N-dimethylaminoethyldecanamide, N,N-diethylaminopropyldecanamide, 
N,N-diethylaminoethyldecanamide, N,N-dibutylaminopropyldecanamide, 
N,N-dimethylaminopropyldodecanamide, N,N-dimethylaminoethyldodecanamide, 
N,N-diethylaminopropyldodecanamide, N,N-diethylaminoethyldodecanamide, 
N,N-dibutylaminopropyldodecanamide, N,N-dibutylaminoethyldodecanamide, 
N,N-dimethylaminopropyltetradecanamide, 
N,N-dimethylaminoethyltetradecanamide, 
N,N-diethylaminopropyltetradecanamide, 
N,N-diethylaminoethyltetradecanamide, 
N,N-dibutylaminopropyltetradecanamide, 
N,N-dibutylaminoethyltetradecanamide, 
N,N-dimethylaminopropylhexadecanamide, 
N,N-diethylaminopropylhexadecanamide, 
N,N-dimethylaminoethylhexadecanamide, N,N-diethylaminoethylhexadecanamide, 
N,N-dibutylaminopropylhexadecanamide, N,N-dibutylaminoethylhexadecanamide, 
N,N-dimethylaminopropyl-9-octadecenamide, 
N,N-dimethylaminopropyloctadecanamide, 
N,N-dimethylaminoethyloctadecanamide, 
N,N-diethylaminopropyloctadecanamide, N,N-diethylaminoethyloctadecanamide, 
N,N-dibutylaminopropyloctadecanamide, N,N-dibutylaminoethyloctadecanamide, 
etc.; and fatty acid esters such as 2-dimethylaminoethyl hexanoate, 
3-dimethylamino-1-propyl hexanoate, 1-dimethylamino-2-propyl hexanoate, 
2-dimethylaminoethyl octanoate, 2-diethylaminoethyl octanoate, 
3-dimethylamino-1-propyl octanoate, 1-diethylamino-2-propyl octanoate, 
2-dimethylaminoethyl decanoate, 2-dibutylaminoethyl decanoate, 
3-diethylamino-1-propyl decanoate, 1-dibutylamino-2-propyl decanoate, 
2-dimethylaminoethylundecylate, 3-dimethylamino-1-propyl undecylate, 
1-dimethylamino-2-propyl undecylate, 6-dimethylamino-1-hexyl undecylate, 
2-dimethylaminoethyl dodecanoate, 2-diethylaminoethyl dodecanoate, 
2-dibutylaminoethyl dodecanoate, 3-dimethylamino-1-propyl dodecanoate, 
1-dimethylamino-2-propyl dodecanoate, 4-dimethylaminophenethyl 
dodecanoate, 2-dimethylaminoethyl tetradecanoate, 2-diethylaminoethyl 
tetradecanoate, 3-diethylamino-1-propyl tetradecanoate, 
1-dimethylamino-2-propyl tetradecanoate, 2-dimethylaminoethyl 
pentadecanoate, 3-dimethylamino-1-propyl pentadecanoate, 
1-dimethylamino-2-propyl pentadecanoate, 2-dimethylaminoethyl 
hexadecanoate, 2-dibutylaminoethyl hexadecanoate, 3-dimethylamino-1-propyl 
hexadecanoate, 1-dimethylamino-2-propyl hexadecanoate, 
4-dimethylamino-1-butyl hexadecanoate, 1-dimethylaminoethyl octadecanoate, 
2-diethylaminoethyl octadecanoate, 3-dimethylamino-1-propyl octadecanoate, 
1-dimethylamino-2-propyl octadecanoate, 2-diethylaminoethyl 
9-octadecenoate, 3-dibutylamino-1-propyl 9-octadecenoate, 
2-dimethylaminoethyl docosanoate, 3-dimethylamino-1-propyl docosanoate, 
1-dimethylamino-2-propyl docosanoate, etc. 
The amidoamines mentioned above can be synthesized by reacting aliphatic 
monocarboxylic acids of 6-22 carbon atoms with N,N-dialkylaminoalkylamines 
such as N,N-dimethylaminopropylamine, N,N-dimethylaminoethylamine, 
N,N-diethylaminopropylamine, N,N-diethylaminoethylamine, 
N,N-dibutylaminopropylamine, N,N-dibutylaminoethylamine, etc. This 
reaction can be carried out by the conventional amidation procedure. Thus, 
this reaction proceeds under heating at 140.degree.-200.degree. C. The 
progress of the reaction can be monitored by measuring the total amine 
value, tertiary amine value, and an acid value. 
The fatty acid esters mentioned above can be synthesized by reacting 
aliphatic monocarboxylic acids of 6-22 carbon atoms with 
N,N-dialkylaminoalcohols such as 2-dimethylaminoethanol, 
2-diethylaminoethanol, 2-dibutylaminoethanol, 3-dimethylamino-1-propanol, 
3-diethylamino-1-propanol, 3-dibutylamino-1-propanol, 
1-dimethylamino-2-propanol, 1-diethylamino-2-propanol, 
1-dibutylamino-2-propanol, 4-dimethylamino-1-butanol, 
6-dimethylamino-1-hexanol, 4-dimethylaminophenethyl alcohol, etc. This 
reaction can be carried out by the conventional esterification method. 
Thus, this reaction proceeds under heating at 140.degree.-230.degree. C. 
The progress of the reaction can be monitored by determining an acid 
value. 
The coating composition of the present invention contains a film-forming 
component. This film-forming component consists of a basic resin and a 
curing agent. However, when the coating composition contains a 
thermoplastic resin or a self-crosslinking resin as the basic resin and 
does not contain a curing agent, the film-forming component is the very 
basic resin. 
The basic resin that can be used includes a variety of resins which are 
used in the conventional coatings, such as chlorinated polyolefin resin, 
acrylic acid resin, polyester resin, alkyd resin, epoxy resin, urethane 
resin, polyacrylate resin, etc. Particularly preferred are chlorinated 
polyolefins which are generally used in primers for bumpers. 
The curing agent that can be used includes polyfunctional compounds or 
resins, such as polyisocyanates, polyamines, melamine, polybasic acids, 
polyepoxides, etc. Of course, when the basic resin is a self-crosslinking 
resin, the basic resin itself contains a crosslinkable component as it is 
the case with polyacrylates, for instance. 
The coating composition of the present invention further contains a 
solvent. The kind of solvent is not limited. Thus, for example, the 
standard organic solvents or water can be employed. The proportion of the 
solvent in the coating composition is not so critical but is preferably 
selected from the range of 50-1,000 parts by weight to each 100 parts by 
weight of the film-forming component. If the proportion of the solvent is 
below the above-mentioned limit of 50 parts by weight, workability is 
sacrificed. On the other hand, if the upper limit of 1,000 parts by weight 
is exceeded, the solid fraction will be undesirably low. In addition to 
the above components, the coating composition of the present invention can 
be supplemented with a pigment, a catalyst and/or other additives where 
necessary. It is generally known that these additional components are used 
or not used depending on the form and objective of application. There is 
virtually no limitation on the kinds of said additives. 
The proportion of the nitrogen-containing compound of general formula (1) 
based on 100 parts by weight of the film-forming component is preferably 
0.01-10 parts by weight, more preferably 0.05-7 parts by weight, and for 
still better results, 0.1-5 parts by weight. If the proportion is less 
than 0.01 part by weight, the coating layer on the resin article obtained 
will not have sufficient electrical conductivity. Any proportion exceeding 
10 parts by weight would be further contributory to electrical 
conductivity but the resultant deterioration of physical properties of the 
coating and bleeding on the surface would virtually cancel the benefit. 
There is no limitation on the technology that can be used for the 
production of the coating composition of the invention. Generally 
speaking, the composition can be produced by adding a nitrogen-containing 
compound of general formula (1), either as it is or as dissolved or 
dispersed in a solvent, in a suitable amount to a coating composition 
(hereinafter referred to as stock coating) which has no antistatic 
properties. Of course, the coating composition can also be produced by 
adding said nitrogen-containing compound of general formula (1) 
simultaneously with the addition of said basic resin, curing agent, and 
other additives. 
Coating with the coating composition containing the nitrogen-containing 
compound of general formula (1) can be carried out by a known coating 
technique which may for example be spray coating, brush coating, dip 
coating, roll coating or casting. For the coating of automotive parts, 
spray coating and dip coating are preferred. 
For the coating of molding articles of resin, the coating composition can 
be applied in any of the conventional application forms such as room 
temperature-curing, lacquer, heat-curing, organic solvent-borne, and 
water-borne coatings. Depending on cases, the substrate article of resin 
may be pretreated before coating so as to improve the adhesion of the 
coating. The pretreatment that can be applied includes a variety of known 
pretreatments such as aqueous rinse, solvent rinse, flame treatment, 
corona discharge treatment, and low pressure plasma treatment. 
The coating thickness and drying conditions for molding articles of resin 
can be similar to those applicable to the stock coating. Taking a primer 
containing a chlorinated polyolefin and not containing a curing agent as 
an example, the coating thickness may be 5-15 .mu.m and the drying 
conditions may be about 10 minutes at 50.degree.-80.degree. C. The same 
conditions apply to the wet-on-wet coating system in which the top coat is 
applied to the primer coat while the latter is still wet. With the coating 
composition using an acrylic or polyester resin as the basic resin and a 
polyisocyanate as the curing agent, the coating thickness may be 20-40 
.mu.m and the drying conditions may be about 20-40 minutes at 
80.degree.-90.degree. C. As to the coating composition containing an 
acrylic or polyester resin as the basic resin and melamine as the curing 
agent, the coating thickness may be 20-40 .mu.m and the drying conditions 
may be about 20-40 minutes at 100.degree.-120.degree. C. 
The molding article of resin that can be used as the substrate includes 
articles of polyolefin resin e.g. polyethylene, polypropylene, 
poly(ethylene-copropylene) rubber-containing polypropylene, etc.!, ABS 
resin, acrylic resin, polyamide resin, poly(vinyl chloride) resin, 
polycarbonate resin, polyacetal resin, polystyrene resin, phenolic resin, 
etc., all of which have high surface resistivity. Furthermore, the molding 
article may be a metal, ceramic, or wooden article coated with any of said 
resin materials. Particularly preferred resins are polyolefin resins which 
are generally used for the manufacture of automotive parts. 
It is also possible to employ a molding article of resin produced by a 
process which comprises kneading an antistatic agent and other additives 
into the abovementioned resin, molding the resulting compound, and 
optionally subjecting it to a surface treatment such as corona discharge 
treatment, low pressure plasma treatment, flame treatment or the like so 
as to adjust its surface resistivity to less than 10.sup.13 .OMEGA.. 
When a molding article of resin with a surface resistivity of less than 
10.sup.13 .OMEGA. is employed, the coating with the coating composition 
containing a nitrogen-containing compound of general formula (1) in step 1 
may be carried out by the electrostatic coating method. 
The molding article of resin may be any of three-dimensional articles and 
two-dimensional articles such as film and sheet. 
The molding article of resin includes but is not limited to automotive 
parts and electrical appliance housings. 
Among the above-mentioned automotive parts are side malls, bumpers, and 
mudguards etc. 
The corona discharge treatment is carried out in such a manner that the 
corona produced by applying a high voltage between two electrical 
conductors at atmospheric pressure is contacted with the surface of the 
substrate (a molding article of resin). The conditions of this treatment 
need not be critically controlled only if a corona discharge takes place. 
Thus, for example, the corona discharge treatment can be carried out at an 
application voltage of about 10-300 KV for 1-600 seconds. 
Particularly when a large-sized article such as an automotive bumper is 
subjected to corona discharge treatment, a corona discharge equipment 
utilizing a high-voltage pulse typically as shown in FIG. 1 can be 
employed. Since this equipment utilizes the high-voltage pulse circuit 
shown in FIG. 2 sparking is seldom induced and the distance between 
electrodes can be increased to accommodate large-sized parts. 
The above corona discharge equipment is now described in detail. 
FIG. 1 shows an external view of the corona discharge equipment. As the 
substrate article of resin 10, a generally U-shaped automotive bumper is 
used and the surface of this article is subjected to corona discharge 
treatment. A plurality of units of said article of resin 10 are caused to 
travel one after another on a roller conveyer 70 installed in the manner 
of a railroad track. The roller conveyer 70, made of insulating resin or 
the like, is disposed on a counter electrode 20. The counter electrode 20 
comprises a plate member having a U-like cross-sectional configuration 
complementary to the bent portions of the molding article of resin 10, 
with its upper surface being covered with a dielectric cladding 60. 
Arranged over the track for the molding article of resin 10, a plurality of 
discharge electrodes 40 each comprising a narrow strip bended to have a 
U-like configuration with fixed spacings therebetween. The lower edge of 
each discharge electrode 40 is configured to be generally complementary to 
the top edge of the molding article of resin 10 and is substantially 
parallel to the surface of the counter electrode 20 with a clearance of 
about a fraction of one meter between them. The top of the discharge 
electrode 40 is supported by connecting metal strips 42 and electrically 
connected thereto. The discharge electrode 40 is removably secured to the 
connecting strip metals 42 by bolt means so that the pitch of discharge 
electrodes 40 can be changed as necessary. Both ends of the connecting 
metal strips 42 are secured to a frame 44. In addition, a high-voltage 
pulse generator 500 is connected to said connecting metal strips 42 via 
high-tension cables. 
Thus, as the molding article of resin 10 is placed on the roller conveyer 
70 disposed over the counter electrode 20, it is transported under the 
discharge electrodes 40. As, in this condition, a high-voltage pulse is 
applied between the discharge electrode 40 and the counter electrode 20, a 
corona discharge takes place to treat the surface of the molding article 
of resin 10. 
FIG. 2 shows the circuitry of the above corona discharge equipment. As 
described above, the resin article 10 is set on the counter electrode 20 
through the dielectric cladding 60, with the discharge electrodes 40 being 
disposed overhead. The clearance W between the discharge electrode 40 and 
the counter electrode 20 is the electrode gap. The circuit connected to 
the discharge electrode 40 and counter electrode 20 includes a pulse 
generator 52 and a high-voltage source 50. The high-voltage source 50 may 
be any of known high-voltage sources which are capable of generating a 
necessary high voltage current from a low-voltage direct current source. 
The circuit constant and other conditions of the pulse generator 52 being 
set to the proper values, a high-voltage pulse showing the desired 
characteristics can be applied between the discharge electrode 40 and the 
counter electrode 20. 
The high-voltage pulse for this corona discharge treatment has a pulse 
width of not less than 1 .mu.sec, an average electric field intensity 
(expressed by applied voltage (wave height) value/distance between 
discharge and counter electrodes) of 4-20 KV/cm, and a pulse frequency of 
not less than 10 pps, preferably 10-300 pps, as taught in JP-A-05339397. 
The treatment time may be 1-600 seconds. 
Where necessary, after the above-mentioned step 2 the work may be further 
coated with a coating composition containing a nitrogen-containing 
compound of general formula (1) and the resulting film be subjected to 
corona discharge treatment. This coating can be carried out by the 
electrostatic coating method, if desired. 
The electrostatic coating in step 3 comprises spraying and depositing a 
coating material having electrostatic charges on the corona 
discharge-treated coating layer obtained by step 2. This coating can be 
carried out by any known method, for example by means of an electric 
centrifugal air or airless atomization coating machine. The application 
voltage is about -30 KV to -120 KV. As the coating material for use in 
this electrostatic coating procedure may be any of the conventional 
electrostatic coating materials such as the urethane, acrylic, alkyd, and 
melamine type coatings. 
In accordance with the present invention, molding articles of resin with 
greatly improved electrical conductivity can be manufactured using resins 
of low electrical conductivity with high productivity. Moreover, the 
present invention enables electrostatic coating with high coating 
efficiency and production of molding articles of resin having an 
attractive appearance. Furthermore, as an unexpected benefit, the impact 
resistance of the coating is improved. The present invention, therefore, 
is particularly useful for the production of automotive parts such as 
bumpers. 
The following examples are intended to describe the present invention in 
further detail and should by no means be construed as defining the scope 
of the invention. 
EXAMPLES 1-23 
(Steps 1 and 2) 
Coating compositions each containing a nitrogen-containing compound of 
general formula (1) in a defined proportion were prepared according to the 
recipes shown in Table 1 and each coating composition was coated on a 
molding article of polypropylene resin (Mitsui Petrochemical Industries, 
Ltd., M-4800; 150 mm.times.60 mm.times.3 mm) which had been rinsed and 
degreased with isopropyl alcohol beforehand. After drying, the surface of 
the coated article of resin was subjected to corona discharge treatment to 
prepare a testpiece. Immediately then, the surface resistivity of the 
testpiece was measured and the coated condition was evaluated. In 
addition, the impact resistance of the coating was determined. 
(Step 3) 
With the above testpiece grounded, it was electrostatically coated with a 
melamine coating (Nippon Bee Chemical, R-320) using a coating machine 
(Ransburg-Gema, .mu..mu.BEL30.phi.) at a static voltage of -40 KV, a 
reciprocation stroke of 400 mm, a spray distance of 300 mm, and a conveyer 
speed of 2.2 m/min. After 30 minutes of drying at 120.degree. C., the 
coating thickness, coating efficiency, and adhesion were determined. 
COMATIVE EXAMPLES 1-10 
The same procedures as described in Examples 1-23 were followed to make 
evaluations. 
The results of Examples 1-23 and Comparative Examples 1-10 are shown in 
Table 1 and Table 2, respectively. It will be apparent from these tables 
that the present invention is superior in film properties, electrical 
conductivity, and coating efficiency. It is also clear that an improved 
impact resistance of the coating was achieved in Examples 1-23. 
TABLE 1 
__________________________________________________________________________ 
Step 1-Step 2 
Nitrogen-containing 
compound of Step 3 
general formula Surface Coat Coating Adhesion 
(1) Stock 
Corona 
resistivity 
Coat 
Impact 
thickness 
efficiency 
Coat Primary 
Secondary 
Species 
Level 
coating 
discharge 
(.OMEGA.) 
quality 
resistance 
(.mu.m) 
(%) quality 
adhesion 
adhesion 
Example 
*1 *2 *3 *4 *5 *6 *7 *8 *9 *6 *10 *11 
__________________________________________________________________________ 
1 A 3 T-1 S-2 8.5 .times. 10.sup.11 
.smallcircle. 
.smallcircle. 
30 75 .smallcircle. 
.smallcircle. 
.smallcircle. 
2 B 3 T-1 S-2 6.4 .times. 10.sup.11 
.smallcircle. 
.smallcircle. 
31 76 .smallcircle. 
.smallcircle. 
.smallcircle. 
3 C 3 T-3 S-2 7.1 .times. 10.sup.11 
.smallcircle. 
.circleincircle. 
31 76 .smallcircle. 
.smallcircle. 
.smallcircle. 
4 D 3 T-3 S-2 4.0 .times. 10.sup.11 
.smallcircle. 
.circleincircle. 
32 77 .smallcircle. 
.smallcircle. 
.smallcircle. 
5 E 3 T-3 S-1 4.3 .times. 10.sup.11 
.smallcircle. 
.circleincircle. 
32 77 .smallcircle. 
.smallcircle. 
.smallcircle. 
6 F 3 T-1 S-1 1.5 .times. 10.sup.11 
.smallcircle. 
.smallcircle. 
34 78 .smallcircle. 
.smallcircle. 
.smallcircle. 
7 F 3 T-1 S-2 7.8 .times. 10.sup.10 
.smallcircle. 
.smallcircle. 
35 82 .smallcircle. 
.smallcircle. 
.smallcircle. 
8 F 3 T-2 S-1 9.1 .times. 10.sup.10 
.smallcircle. 
.circleincircle. 
35 82 .smallcircle. 
.smallcircle. 
.smallcircle. 
9 G 3 T-1 S-2 8.9 .times. 10.sup.10 
.smallcircle. 
.smallcircle. 
35 82 .smallcircle. 
.smallcircle. 
.smallcircle. 
10 H 3 T-2 S-2 6.0 .times. 10.sup.10 
.smallcircle. 
.circleincircle. 
36 83 .smallcircle. 
.smallcircle. 
.smallcircle. 
11 I 3 T-2 S-2 7.1 .times. 10.sup.10 
.smallcircle. 
.circleincircle. 
35 82 .smallcircle. 
.smallcircle. 
.smallcircle. 
12 F 0.08 
T-1 S-2 8.0 .times. 10.sup.11 
.smallcircle. 
.smallcircle. 
30 75 .smallcircle. 
.smallcircle. 
.smallcircle. 
13 F 0.5 
T-1 S-2 4.5 .times. 10.sup.11 
.smallcircle. 
.smallcircle. 
32 77 .smallcircle. 
.smallcircle. 
.smallcircle. 
14 F 5 T-1 S-2 5.3 .times. 10.sup.10 
.smallcircle. 
.circleincircle. 
36 83 .smallcircle. 
.smallcircle. 
.smallcircle. 
15 F 8 T-1 S-2 3.4 .times. 10.sup.10 
.smallcircle. 
.circleincircle. 
36 83 .smallcircle. 
.smallcircle. 
.smallcircle. 
16 J 3 T-1 S-2 9.2 .times. 10.sup.10 
.smallcircle. 
.smallcircle. 
35 82 .smallcircle. 
.smallcircle. 
.smallcircle. 
17 J 0.5 
T-1 S-2 5.1 .times. 10.sup.11 
.smallcircle. 
.smallcircle. 
32 77 .smallcircle. 
.smallcircle. 
.smallcircle. 
18 J 8 T-1 S-2 7.6 .times. 10.sup.10 
.smallcircle. 
.circleincircle. 
35 82 .smallcircle. 
.smallcircle. 
.smallcircle. 
19 K 3 T-1 S-2 1.0 .times. 10.sup.11 
.smallcircle. 
.circleincircle. 
34 79 .smallcircle. 
.smallcircle. 
.smallcircle. 
20 L 3 T-1 S-1 1.2 .times. 10.sup.11 
.smallcircle. 
.smallcircle. 
34 79 .smallcircle. 
.smallcircle. 
.smallcircle. 
21 M 3 T-1 S-2 3.5 .times. 10.sup.11 
.smallcircle. 
.circleincircle. 
32 77 .smallcircle. 
.smallcircle. 
.smallcircle. 
22 N 3 T-1 S-2 3.9 .times. 10.sup.11 
.smallcircle. 
.smallcircle. 
32 77 .smallcircle. 
.smallcircle. 
.smallcircle. 
23 O 3 T-1 S-2 6.9 .times. 10.sup.11 
.smallcircle. 
.smallcircle. 
31 76 .smallcircle. 
.smallcircle. 
.smallcircle. 
__________________________________________________________________________ 
*1 A: N,Ndimethylaminopropylhexanamide 
B: N,Ndiethylaminopropyloctanamide 
C: 2Diethylaminoethyl octanoate 
D: N,Ndiethylaminoethyldecanamide 
E: 2Dibutylaminoethyl decanoate 
F: N,Ndiethylaminopropyldodecanamide 
G: 2Dimethylaminoethyl dodecanoate 
H: N,Ndimethylaminopropyldodecanamide 
I: 2Dibutylaminoethyl dodecanoate 
J: 3Diethylamino-1-propyl tetradecanoate 
K: N,Ndibutylaminoethylhexadecanamide 
L: 4Dimethylamino-1-butyl hexadecanoate 
M: N,Ndiethylaminopropyloctadecanamide 
N: M/2diethylaminoethyl 9octadecenoate = 1/1 (wt/wt) 
O: 2Dimethylaminoethyl docosanoate 
*2 The amount in parts by weight based on 100 parts by weight of the 
filmforming component in the coating composition. 
*3 T1: Primer RB195 manufactured by Nippon Bee Chemical. 
Base resin: chlorinated polyolefin 
Curing agent: None 
Coating was carried out by the air spray method in a dry thickness of 
about 10 .mu.m and drying was carried out at 50.degree. C. for 10 minutes 
T2: Coating R215 manufactured by Nippon Bee Chemical. 
Base resin: polyesteracrylic 
Curing agent: a polyisocyanate 
Coating was carried out by the air spray method in a dry thickness of 
about 20 .mu.m and, after a setting time of about 10 minutes, drying was 
carried out at 80.degree. C. for 30 minutes. 
T3: Coating R207 manufactured by Nippon Bee Chemical. 
Base resin: acrylic 
Curing agent: melamine 
Coating was carried out by the air spray method in a dry thickness of 
about 20 .mu.m and, after a setting time of about 10 minutes, drying was 
carried out at 120.degree. C. for 30 minutes. 
*4 S1: Corona discharge treatment 
(Conditions): The coated surface of the resin article was subjected to 
corona discharge treatment at an application voltage of 30 KV for 20 
seconds. The electrode gap was 1 cm. (Highfrequency source: Kasuga Denki 
Highfrequency Source HFS203) 
S2: Corona discharge treatment with a highvoltage pulse 
(Conditions): The coated surface of the resin article was subjected to 
corona discharge treatment at an application voltage of 190 KV for 20 
seconds. The electrode gap was 35 cm. (The corona discharge equipment 
shown in FIG. 1 was used) 
*5 The surface resistivity immediately after corona discharge treatment 
was measured 1 minute after applying a voltage of 500 V using Advantest's 
ultrahigh resistance meter R8340 (relative humidity 65%, atmospheric 
temperature 20.degree. C.) 
*6 The condition of the coating was visually evaluated in terms of 
roughness, gloss, and coating defect (cratering, hollow, color shading). 
.smallcircle.: good 
x: no good 
*7 Impact resistance: Using a DuPont impact tester, an impact load of 1 k 
with a falling ball diameter of 1/2 inch was applied to the coated surfac 
of the testpiece and the falling distance not causing any abnormality in 
the coating was determined. The evaluation scale according to the falling 
distance not causing any abnormality was as follows. 
.circleincircle.: excellent (&gt;50 cm) 
.smallcircle.: good (50 cm) 
.DELTA.: practically acceptable (45 cm) 
x: poor (&lt;45 cm) 
*8 Coating thickness: The coating thickness was visually determined by 
microscopic observation of the surface of the coated resin article. 
*9 Coating efficiency: From the relationship of the difference between th 
weight before coating and that after coating with the bonedry weight of 
the delivered coating, the coating efficiency was calculated by means of 
the following equation. 
Coating efficiency (%) 
(weight of testpiece after coating - weight of testpiece before 
coating)/Bonedry weight of delivered coating .times. 100 
*10 Using a singleblade razor, the electrostatically coated surface of th 
testpiece was crosshatched at a pitch of 2 mm to provide 100 squares. An 
adhesive cellophan tape (JIS Z 1552) was firmly applied against the 
crosshatched surface and peeled off in a stroke at an angle of 90.degree. 
to evaluate the peeling resistance. 
.smallcircle.: not peeled 
x: peeled 
*11 The electrostatically coated testpiece was immersed in water at 
40.degree. C. for 240 hours and the peeling resistance was evaluated by 
the same method as *10. 
.smallcircle.: not peeled 
x: peeled 
TABLE 2 
__________________________________________________________________________ 
Step 1-Step 2 
Nitrogen-containing 
compound of Step 3 
general formula Surface Coat Coating Adhesion 
(1) Stock 
Corona 
resistivity 
Coat 
Impact 
thickness 
efficiency 
Coat 
Primary 
Secondary 
Comparative 
Species 
Level 
coating 
discharge 
(.OMEGA.) 
quality 
resistance 
(.mu.m) 
(%) quality 
adhesion 
adhesion 
Example 
*1 *2 *3 *4 *5 *6 *7 *8 *9 *6 *10 *11 
__________________________________________________________________________ 
1 None 0 T-1 None 1.5 .times. 10.sup.16 
.smallcircle. 
x 7 23 .smallcircle. 
.smallcircle. 
.smallcircle. 
2 None 0 T-2 None 1.2 .times. 10.sup.16 
.smallcircle. 
.DELTA. 
8 25 .smallcircle. 
.smallcircle. 
.smallcircle. 
3 None 0 T-3 None 2.1 .times. 10.sup.16 
.smallcircle. 
.DELTA. 
7 23 .smallcircle. 
.smallcircle. 
.smallcircle. 
4 None 0 T-1 S-1 1.3 .times. 10.sup.16 
.smallcircle. 
x 8 25 .smallcircle. 
.smallcircle. 
.smallcircle. 
5 None 0 T-1 S-2 1.0 .times. 10.sup.16 
.smallcircle. 
x 8 25 .smallcircle. 
.smallcircle. 
.smallcircle. 
6 None 0 T-3 S-2 1.8 .times. 10.sup.16 
.smallcircle. 
.DELTA. 
7 23 .smallcircle. 
.smallcircle. 
.smallcircle. 
7 F 3 T-1 None 9.3 .times. 10.sup.15 
.smallcircle. 
.smallcircle. 
8 25 .smallcircle. 
.smallcircle. 
.smallcircle. 
8 I 3 T-1 None 1.0 .times. 10.sup.16 
.smallcircle. 
.smallcircle. 
8 25 .smallcircle. 
.smallcircle. 
.smallcircle. 
9 F 3 T-2 None 9.5 .times. 10.sup.15 
.smallcircle. 
.smallcircle. 
8 25 .smallcircle. 
.smallcircle. 
.smallcircle. 
10 I 3 T-3 None 1.1 .times. 10.sup.16 
.smallcircle. 
.smallcircle. 
8 25 .smallcircle. 
.smallcircle. 
.smallcircle. 
__________________________________________________________________________ 
*1-*11: Same as defined for Table 1. 
EXAMPLES 24-29 
(Steps 1 and 2) 
Coating compositions each containing a nitrogen-containing compound of 
general formula (1) in a defined proportion were prepared according to the 
recipes shown in Table 3. Each of the coating compositions thus prepared 
was coated on an automotive polypropylene bumper (surface resistivity 
1.0.times.10.sup.16 .OMEGA.) and, after drying, the coated surface was 
subjected to corona discharge treatment. Immediately then, the surface 
resistivity was measured and the condition of the coating was evaluated. 
The impact resistance of the coating was also measured. 
(Step 3) 
With the above polypropylene bumper grounded, electrostatic coating was 
carried out with a melamine coating (Nippon Bee Chemical, R-320) using a 
coating machine (Ransburg-Gema, .mu..mu.BEL30.phi.) at a static voltage of 
-40 KV, a reciprocation stroke of 400 mm, a spray distance of 300 mm, and 
a conveyer speed of 2.2 m/min. and drying was carried out at 120.degree. 
C. for 30 minutes. The coating thickness, coating efficiency, and adhesion 
were then determined. 
EXAMPLE 30 
(Steps 1 and 2) 
A coating composition containing a nitrogen-containing compound of general 
formula (1) in a defined proportion according to the recipe shown in Table 
3 and an automotive polypropylene bumper contaning an additive (surface 
resistivity 5.2.times.10.sup.11 .OMEGA.) was electrostatically coated with 
the composition. After drying, the coated surface was subjected to corona 
discharge treatment and immediately then the surface resistivity was 
measured and the coat condition was evaluated. The impact resistance of 
the coating was also determined. 
The bumper used above was a bumper which had been molded from a 
polypropylene containing 0.5% of a nitrogen-containing compound of general 
formula (1) (F) (surface resistivity 3.1.times.10.sup.15 .OMEGA.), rinsed 
and degreased with isopropyl alcohol, and subjected to corona discharge 
treatment (S-2). 
(Step 3) 
The procedure used in Examples 24-29 was repeated. 
EXAMPLE 31 
(Steps 1 and 2) 
A coating composition containing a nitrogen-containing compound of general 
formula (1) in a defined proportion according to the recipe shown in Table 
3 was prepared and an automotive polypropylene bumper containing an 
additive (surface resistivity 4.5.times.10.sup.11 .OMEGA.) was 
electrostatically coated with the coating composition, dried, and 
subjected to corona discharge treatment. Immediately then, the surface 
resistivity was measured and the condition of the coating was evaluated. 
The impact resistance of the coating was also determined. 
The bumper used above was a bumper which had been molded from a 
polypropylene containing 0.5% of a nitrogen-containing compound of general 
formula (1) (I) (surface resistivity 3.1.times.10.sup.15 .OMEGA.) and 
subjected to corona discharge treatment (S-2). 
(Step 3) 
The corresponding procedure used in Examples 24-29 was repeated. 
COMATIVE EXAMPLES 11-14 
The procedure described in Examples 24-29 was repeated. 
The results of examples 24-31 and Comparative Examples 11-14 are shown in 
Table 3 and Table 4, respectively. It will be apparent from these tables 
that in the production of large-sized articles such as automotive bumpers, 
the corona discharge treatment using a high-voltage pulse is conducive to 
excellent results in the physical properties and electrical conductivity 
of the coating and coating efficiency. It is also clear that the impact 
resistance of the coating is excellent in Examples 24-31. 
TABLE 3 
__________________________________________________________________________ 
Step 1-Step 2 
Nitrogen-containing 
compound of Step 3 
general formula Surface Coat Coating Adhesion 
(1) Stock 
Corona 
resistivity 
Coat 
Impact 
thickness 
efficiency 
Coat 
Primary 
Secondary 
Species 
Level 
coating 
discharge 
(.OMEGA.) 
quality 
resistance 
(.mu.m) 
(%) quality 
adhesion 
adhesion 
Example 
*1 *2 *3 *4 *5 *6 *7 *8 *9 *6 *10 *11 
__________________________________________________________________________ 
24 F 0.5 
T-1 S-2 4.6 .times. 10.sup.11 
.smallcircle. 
.smallcircle. 
33 59 .smallcircle. 
.smallcircle. 
.smallcircle. 
25 F 3 T-1 S-2 8.1 .times. 10.sup.10 
.smallcircle. 
.smallcircle. 
34 60 .smallcircle. 
.smallcircle. 
.smallcircle. 
26 F 8 T-1 S-2 3.1 .times. 10.sup.10 
.smallcircle. 
.circleincircle. 
35 61 .smallcircle. 
.smallcircle. 
.smallcircle. 
27 I 0.5 
T-1 S-2 5.1 .times. 10.sup.11 
.smallcircle. 
.smallcircle. 
33 59 .smallcircle. 
.smallcircle. 
.smallcircle. 
28 I 3 T-1 S-2 7.5 .times. 10.sup.10 
.smallcircle. 
.smallcircle. 
34 60 .smallcircle. 
.smallcircle. 
.smallcircle. 
29 I 8 T-1 S-2 4.0 .times. 10.sup.10 
.smallcircle. 
.circleincircle. 
35 61 .smallcircle. 
.smallcircle. 
.smallcircle. 
30 F 3 T-1 S-2 8.2 .times. 10.sup.10 
.smallcircle. 
.smallcircle. 
34 60 .smallcircle. 
.smallcircle. 
.smallcircle. 
31 I 3 T-1 S-2 7.9 .times. 10.sup.10 
.smallcircle. 
.smallcircle. 
34 60 .smallcircle. 
.smallcircle. 
.smallcircle. 
__________________________________________________________________________ 
*1-*11: Same as defined for Table 1. 
TABLE 4 
__________________________________________________________________________ 
Step 1-Step 2 
Nitrogen-containing 
compound of Step 3 
general formula Surface Coat Coating Adhesion 
(1) Stock 
Corona 
resistivity 
Coat 
Impact 
thickness 
efficiency 
Coat 
Primary 
Secondary 
Comparative 
Species 
Level 
coating 
discharge 
(.OMEGA.) 
quality 
resistance 
(.mu.m) 
(%) quality 
adhesion 
adhesion 
Example 
*1 *2 *3 *4 *5 *6 *7 *8 *9 *6 *10 *11 
__________________________________________________________________________ 
11 F 3 T-1 S-1 --* -- -- -- -- -- -- -- 
12 None 0 T-1 S-2 1.0 .times. 10.sup.16 
.smallcircle. 
x 8 25 .smallcircle. 
.smallcircle. 
.smallcircle. 
13 F 3 T-1 None 9.2 .times. 10.sup.15 
.smallcircle. 
.smallcircle. 
7 23 .smallcircle. 
.smallcircle. 
.smallcircle. 
14 I 3 T-1 None 9.8 .times. 10.sup.15 
.smallcircle. 
.smallcircle. 
8 25 .smallcircle. 
.smallcircle. 
.smallcircle. 
__________________________________________________________________________ 
*1-*11: Same as defined for Table 1. 
*: Because of the small electrode gap (1 cm), bumpers could not be 
treated.