JPH0987403A - Improvement of electroconductivity of resin molding and production of coated material made of resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve electroconductivity of a resin molding in good productivity without using a primer containing an inorganic semiconductor substance by applying a coating material containing a specific nitrogen-containing compound to a resin molding and subjecting the surface of the resultant coating film to corona discharge treatment. SOLUTION: A coating material containing (A) a film-forming component and (B) a nitrogen-containing compound of the formula R<1> -Y R<1> is a 5-21C alkyl or an alkenyl; Y is formula I or formula II [R<2> and R<3> are each a 1-4C alkyl; (m) is 2-3; R<4> is H or CH3 ; A is (CH2 )n or formula III; (n) is 1-5]} is applied to a resin molding (e.g. a molding of a polyethylene, acrylic resin, etc.) and the surface of the resultant coating film is subjected to corona discharge treatment. The component A includes e.g. that comprising a substrate resin such as polyester and a polyisocyanate as a curing agent. The component B includes amineamides such as N, N-dimethylaminopropylhexanamide or fatty acid esters such as hexanoic acid 2-dimethylaminoethanol.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for improving the electrical conductivity of a resin molding and a method for producing a resin coated article using the method.

[0002]

2. Description of the Related Art As a conventional method for coating a resin molding,
For example, as described in JP-A-6-165966, a polypropylene-made article to be coated is coated with a conductive primer containing an inorganic conductive material such as conductive carbon black or graphite, and then made conductive. There is a method of electrostatic coating.

However, as described in JP-A-6-165966, in order to evenly distribute the conductive substances such as conductive carbon black and graphite on the surface of the polypropylene article, these conductive substances are used as a primer. It is necessary to add a large amount to. Therefore, there are problems in dispersion stability of the conductive material and cost.

Further, recently, a method has been disclosed in which a nitrogen-containing compound is kneaded into a raw material for a resin molded body, the kneaded product is molded, and the surface of the resulting molded body is subjected to a reduced pressure plasma treatment (Japanese Patent Laid-Open No. Hei 10 (1999) -242242). 7-173308).

However, in this method, since the plasma treatment is a batch method, it is not suitable for continuous treatment, and there remains a problem in productivity in mass production.

[0006]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned drawbacks of the conventional method, does not use a primer containing an inorganic conductive material, and is excellent in productivity, and the conductivity of the resin molding is improved. An object of the present invention is to provide a property improving method and a method for producing a resin coated article using the method.

[0007]

In the present invention, a resin molded product is coated with a coating material containing a specific nitrogen-containing compound, and the surface of the resulting coating film is subjected to corona discharge treatment to obtain the conductivity of the coating film. The inventors have found that the coating film can be improved to a suitable one for electrostatic coating characteristics, and have solved the above problems.

That is, in the first invention of the present application, a coating material containing a film-forming component and a nitrogen-containing compound represented by the following general formula (1) is applied to a resin molded article, and the surface of the obtained coating film is coated. The method includes a step (step 1) of corona discharge treatment, and improves the conductivity of the resin molding by improving the conductivity of the coating film. Further, the second invention of the present application is the step 1
The method for producing a resin-coated article is characterized in that it comprises a step (step 2) of spraying and attaching a charged coating material to the coating film obtained in step 2 and performing electrostatic coating.

Embedded image In the method of the present invention, after the coating film is formed, the nitrogen-containing compound represented by the general formula (1) present in the surface layer of the coating film is more likely to be present in the surface layer by the corona discharge treatment, and a part thereof is quaternized. It is considered that the surface resistance of the coating film is lowered due to the synergistic effect of, for example, and a resin molded product having improved conductivity and high quality can be obtained. Furthermore, the effect of surface modification by corona discharge treatment is added, and electrostatic coating with excellent coatability becomes possible.

Further, since the corona discharge treatment is carried out at normal pressure, continuous treatment is possible and the productivity is excellent.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In the general formula (1), R ¹ is an alkyl group or an alkenyl group having 5 to 21 carbon atoms,
Preferred is an alkyl group or alkenyl group having 7 to 17 carbon atoms, and particularly preferred is an alkyl group or alkenyl group having 9 to 15 carbon atoms.

Examples of the nitrogen-containing compound represented by the general formula (1) include N, N-dimethylaminopropylhexanamide, N, N-diethylaminopropylhexanamide, N, N-diethylaminoethylhexanamide and N, N. -Dimethylaminopropyl octanamide,
N, N-diethylaminopropyl octanamide, N,
N-diethylaminoethyloctaneamide, N, N-dibutylaminopropyloctaneamide, N, N-dibutylaminoethyloctaneamide, N, N-dimethylaminopropyldecaneamide, N, N-dimethylaminoethyldecaneamide, N, N -Diethylaminopropyl decanamide, N, N-diethylaminoethyl decanamide, N, N-dibutylaminopropyl decanamide,
N, N-dimethylaminopropyl dodecane amide, N,
N-dimethylaminoethyldodecane amide, N, N-diethylaminopropyl dodecane amide, N, N-diethylaminoethyl dodecane amide, N, N-dibutylaminopropyl dodecane amide, N, N-dibutylaminoethyl dodecane amide, N, N- Dimethylaminopropyl tetradecanoamide, N, N-dimethylaminoethyl tetradecanoamide, N, N-diethylaminopropyl tetradecanoamide, N, N-diethylaminoethyl tetradecanoamide, N, N-dibutylaminopropyl tetradecanoamide, N, N-dibutylamino Ethyl tetradecanoamide, N, N-dimethylaminopropyl hexadecanoamide, N, N-diethylaminopropyl hexadecanoamide, N, N-dimethylaminoethyl hexadecanoamide, N, -Diethylaminoethyl hexadecane amide, N, N-dibutylaminopropyl hexadecane amide, N, N-dibutylaminoethyl hexadecane amide, N, N-dimethylaminopropyl-9-octadecenamide, N, N-dimethylaminopropyl octadecane amide, Amidoamines such as N, N-dimethylaminoethyl octadecane amide, N, N-diethylaminopropyl octadecane amide, N, N-diethylaminoethyl octadecane amide, N, N-dibutylaminopropyl octadecane amide, N, N-dibutylaminoethyl octadecane amide , Hexanoic acid 2-dimethylaminoethanol, hexanoic acid 3-dimethylamino-1-
Propanol, hexanoic acid 1-dimethylamino-2-propanol, octanoic acid 2-dimethylaminoethanol, octanoic acid 2-diethylaminoethanol, octanoic acid 3-dimethylamino-1-propanol, octanoic acid 1-diethylamino-2-propanol, decane Acid 2
-Dimethylaminoethanol, 2-dibutylaminoethanol decanoate, 3-diethylamino-1-propanol decanoate, 1-dibutylamino-2-propanol decanoate, 2-dimethylaminoethanol undecylate,
3-dimethylamino-1-propanol undecylate,
1-dimethylamino-2-propanol undecylate,
6-dimethylamino-1-hexanol undecylate,
Dodecanoic acid 2-dimethylaminoethanol, dodecanoic acid 2-diethylaminoethanol, dodecanoic acid 2-dibutylaminoethanol, dodecanoic acid 3-dimethylamino-
1-propanol, dodecanoic acid 1-dimethylamino-2
-Propanol, 4-dimethylaminophenethyl alcohol dodecanoate, 2-dimethylaminoethanol tetradecanoate, 2-diethylaminoethanol tetradecanoate, 3-diethylamino-1-propanol tetradecanoate, 1-dimethylamino-2-propanol tetradecanoate, pentadecanoic acid 2-dimethylaminoethanol, 3-dimethylamino-1-propanol pentadecanoate, 1-dimethylamino-2-propanol pentadecanoate, 2-dimethylaminoethanol hexadecanoate, 2-dibutylaminoethanol hexadecanoate, 3-dimethylaminohexadecanoate -1-propanol,
Hexadecanoic acid 1-dimethylamino-2-propanol, hexadecanoic acid 4-dimethylamino-1-butanol, octadecanoic acid 2-dimethylaminoethanol, octadecanoic acid 2-diethylaminoethanol, octadecanoic acid 3-dimethylamino-1-propanol, octadecanoic acid 1-dimethylamino-2-propanol, 9-
2-diethylaminoethanol octadecenoic acid, 3-dibutylamino-1-propanol 9-octadecenoate,
Docosanoic acid 2-dimethylaminoethanol, docosanoic acid 3-dimethylamino-1-propanol, docosanoic acid 1
And fatty acid esters such as dimethylamino-2-propanol.

The amidoamines include aliphatic monocarboxylic acids having 6 to 22 carbon atoms, N, N-dimethylaminopropylamine, N, N-dimethylaminoethylamine,
It is obtained by a reaction with N, N-dialkylaminoalkylamine such as N, N-diethylaminopropylamine, N, N-diethylaminoethylamine, N, N-dibutylaminopropylamine, N, N-dibutylaminoethylamine. The reaction is performed by a known reaction method for amide formation. That is, the reaction proceeds by heating at a temperature of 140 to 200 ° C. The progress of the reaction is checked by measuring the total amine value, the tertiary amine value and the acid value.

The fatty acid ester has 6 to 22 carbon atoms.
With an aliphatic monocarboxylic acid of 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-
Obtained by reaction with N, N-dialkylamino alcohols such as 1-hexanol and 4-dimethylaminophenethyl alcohol. The reaction is carried out by a known reaction method for ester formation. That is, 140 to 230
The reaction proceeds by heating at a temperature of ° C.
The degree of progress of the reaction is checked by measuring the acid value.

The paint used in the method of the present invention contains a film-forming component. This film forming component is composed of a base resin and a curing agent. However, in a coating material containing a thermoplastic resin or a self-curing base resin that does not contain a curing agent, the film forming component is the base resin itself.

Specific examples of the base resin include those usually used for paints such as chlorinated polyolefin, acrylic, polyester, alkyd, epoxy, urethane and polyacrylate.

Specific examples of the curing agent include polyisocyanates, polyamines, melamines, polybasic acids, and polyfunctional compounds or resins such as polyepoxy.
The self-curing base resin described above has a curing agent portion in the base resin, such as polyacrylate.

The coating material may contain a solvent, a pigment, a catalyst and an additive as required. It is generally known that in paints, these components may or may not be included depending on their form and purpose. The solvent is not particularly limited and, for example, a general-purpose organic solvent and water can be used. Also, the types of pigments, catalysts and additives are not particularly limited.

The amount of the nitrogen-containing compound represented by the general formula (1) used is 0.01 with respect to 100 parts by weight of the film-forming component.
-10 parts by weight, preferably 0.05 to 7 parts by weight, particularly preferably 0.1 to 5 parts by weight. When the amount is less than 0.01 part by weight, the electrical conductivity of the coating film on the surface of the resin molded body is insufficient. Further, the addition of more than 10 parts by weight is preferable for improving the electroconductivity, but it has no great advantage because it deteriorates the physical properties of the paint film and causes bleeding on the surface of the paint film.

The method for obtaining the coating material used in the present invention is not particularly limited. Generally, to a coating material having no antistatic property (hereinafter referred to as a raw material coating material), a predetermined amount of a nitrogen-containing compound represented by the general formula (1) is added as it is or dissolved or dispersed in a solvent. Is obtained by Of course, it is also possible to manufacture a coating material by adding the coating material such as the base resin and the curing agent together with the nitrogen-containing compound represented by the general formula (1).

As a coating method of the coating material containing the nitrogen-containing compound represented by the general formula (1), known methods such as spray coating, brush coating coating, dip coating, roll coating and flow coating are used.

As the paint form used for coating the resin molded body, there are room temperature curing type, lacquer type, thermosetting type, and commonly used paint forms such as organic solvent type paints, water-based paints and powder paints. Can also be used. In some cases, the resin molded body may be pretreated before coating in order to increase the adhesion strength of the coating film. Examples of this pretreatment include known methods such as water washing, solvent washing, flame treatment, corona discharge treatment, and reduced pressure plasma treatment.

The coating film thickness and the drying conditions when the resin molded product is coated are in accordance with the drying conditions of the respective raw material paints.
For example, when using a chlorinated polyolefin as a base resin and using a curing agent-free primer coating,
The film thickness is 5 to 15 μm, and the drying is at 50 to 80 ° C. for about 10 minutes. The same conditions are applied to so-called wet-on-wet coating, in which the top coat is applied to the undried primer and the heating is performed integrally. In the coating using acrylic or polyester as the base resin and polyisocyanate as the curing agent, the film thickness is 20 to 40 μm.
m, and the drying is at 80 to 90 ° C. for about 20 to 40 minutes.
In the coating using acrylic or polyester as the base resin and melamine as the curing agent, the film thickness is 20 to 4
The drying is performed at 100 to 120 ° C. for about 20 to 40 minutes.

The resin moldings include polyolefin resins such as polyethylene, polypropylene and polypropylene containing ethylene-propylene copolymer rubber, ABS resins, acrylic resins, polyamide resins, polyvinyl chloride resins, polycarbonate resins, polyacetal resins, polystyrene resins, Any molded product of a resin having a high surface resistance value such as phenol resin can be used. Alternatively, metal, ceramic, or wood coated with the resin may be used.

After the resin is kneaded with an antistatic agent and the like, the resin is molded, and then subjected to a surface treatment such as a corona discharge treatment, a reduced pressure plasma treatment, a flame treatment or the like so that the surface resistance is 1 or less.
It is also possible to use a resin molded body which is less than 0 ¹³ Ω.

When a resin molded body having a surface resistance of less than 10 ¹³ Ω is used, in step 1, electrostatic coating is used as a method for coating the coating material containing the nitrogen-containing compound represented by the general formula (1). You may.

The shape of the resin molded body may be any shape such as a molded body having a three-dimensional shape, a sheet or a film.

Specific examples of the resin molded body include automobile parts and household appliances housings.

Examples of automobile parts include side moldings, bumpers and mat guards.

As the corona discharge treatment method, there is used a method in which a corona generated when a high voltage is applied between two conductors is brought into contact with the surface of an object to be treated (molded body) at normal pressure. The treatment condition may be any condition that causes corona discharge, for example, an applied voltage of about 10 to 300 KV,
The processing time may be 1 to 600 seconds.

In particular, when a large molded article such as a bumper is subjected to corona discharge treatment, for example, a corona discharge treatment apparatus utilizing a high voltage pulse as shown in FIG. 1 may be used. Since this apparatus uses the high-voltage pulse circuit shown in FIG. 2, sparks are unlikely to occur and the distance between the electrodes can be increased, so that large molded products can be processed.

The corona discharge treatment device will be described below.

FIG. 1 shows an external structure of a corona discharge treatment device. As the resin molded product 10, an automobile bumper having a substantially U-shape is used, and the surface of the resin molded product 10 is subjected to corona discharge treatment. Many resin molded products 10
It is sent side by side on a roller conveyor 70 laid in the shape of two rails. The roller conveyor 70 includes the counter electrode 20.
It is installed on top of and is made of insulating resin. The counter electrode 20 is made of a plate material having a U-shaped cross section along the lower end shape of the resin molded product 10, and the upper surface of the counter electrode 20 is covered with a dielectric 60.

Discharge electrodes 40 in the shape of a thin strip bent in a U shape are arranged at regular intervals above the traveling path of the resin molded product 10. The shape of the lower end edge of the discharge electrode 40 roughly corresponds to the shape of the upper end edge of the resin molded product 10, and the lower end edge of the discharge electrode 40 and the surface of the counter electrode 20 are arranged substantially parallel to each other, and are about several tens cm. Are spaced. The upper portion of the discharge electrode 40 is supported by a strip-shaped connecting fitting 42 and is electrically connected integrally. The discharge electrode 40 is detachably attached to the connection fitting 42 with a bolt or the like, and the attachment pitch of the discharge electrode 40 can be changed as necessary. Both ends of the connection fitting 42 are attached to the frame 44. The high-voltage pulse generator 500 is connected to the connection fitting 42 via a high-voltage cable or the like.

Therefore, on the counter electrode 20, the resin molded product 10 mounted on the roller conveyor 70 is transferred under the discharge electrode 40, and a high voltage pulse is applied between the discharge electrode 40 and the counter electrode 20. Corona discharge can be applied to generate corona discharge, and the surface of the resin molded product 10 can be subjected to corona discharge treatment.

FIG. 2 shows a circuit structure of the corona discharge treatment device. The resin molded product 10 is mounted on the counter electrode 20 via the dielectric 60, and the discharge electrode 40 is arranged above the resin molded product 10. The distance W between the discharge electrode 40 and the counter electrode 20 is the inter-electrode distance. A pulse forming circuit 52 is provided in the circuit connecting the discharge electrode 40 and the counter electrode 20.
And a high voltage power supply 50. High voltage power supply 50
Is a device that can generate a desired high-voltage current from a low-voltage DC power source, as in various ordinary high-voltage devices. By appropriately setting conditions such as the circuit constant of the pulse forming circuit 52, a high voltage pulse exhibiting desired characteristics can be generated by the discharge electrode 4.
It will be added between 0 and the counter electrode 20.

The treatment conditions of the corona discharge treatment method generated by a high voltage pulse are as follows (as described in JP-A-5-339397): [Applied voltage (peak value) / discharge electrode and counter electrode Is a high voltage pulse having an average electric field strength of 4 to 20 KV / cm and a pulse frequency of 10 pps or more. The processing time may be 1 to 600 seconds.

In the present invention, a coating containing a nitrogen-containing compound represented by the general formula (1) may be further applied after step 1 and the surface of the obtained coating film may be subjected to corona discharge treatment. Electrostatic coating is also possible as a coating method at that time.

Next, as the electrostatic coating method in step 2, any method using an electric centrifugal force air, an airless atomizing type coating machine or the like can be used, and the applied voltage is from -30 KV to -12.
It is about 0 KV. As the type of paint used for electrostatic coating, any of commonly used paints such as urethane type, acrylic type, alkyd type and melamine type can be used.

[0039]

EXAMPLES Examples 1 to 23 (Step 1) As shown in Table 1, a paint containing a predetermined amount of a nitrogen-containing compound represented by the general formula (1) was prepared, and the paint was washed with isopropyl alcohol. Degreased polypropylene resin molding (M-4800, Mitsui Petrochemical, 1
After coating on 50 mm × 60 mm × 3 mm) and drying, the surface of this resin molding was subjected to corona discharge treatment to obtain a test piece. Immediately, the surface resistance of this test piece was measured and the state of the coating film was observed. Furthermore, the impact resistance of the obtained coating film was measured.

(Step 2) Next, the test piece obtained above is grounded, static voltage -40 KV, reciprocating stroke 4
00 mm, spraying distance 300 mm, conveyor speed 2.
2m / min coating machine (Ransburg Gemma, μμBE
A melamine-based paint (R-320, manufactured by Nippon Bee Chemical Co., Ltd.) was electrostatically coated with L30φ), and after drying at 120 ° C. for 30 minutes, the film thickness, coating efficiency and adhesion were measured.

Comparative Examples 1 to 10 The same procedure as in Examples 1 to 23 was carried out.

Next, Examples 1 to 23 and Comparative Examples 1 to 1
The results of 0 are shown in Table 1 and Table 2, respectively. As is clear from these tables, excellent effects of the coating film physical properties, conductivity and coating efficiency in the present invention were confirmed. further,
In Examples 1 to 23, the impact resistance of the coating film was found to be excellent.

[0043]

[Table 1] * 1 A: N, N-dimethylaminopropylhexanamide B: N, N-diethylaminopropyl octanamide C: Octanoic acid 2-diethylaminoethanol D: N, N-Diethylaminoethyl decanamide E: Decanoic acid 2-dibutylaminoethanol F: N, N-diethylaminopropyl dodecanoamide G: dodecanoic acid 2-dimethylaminoethanol H: N, N-dimethylaminopropyl dodecanoamide I: dodecanoic acid 2-dibutylaminoethanol J: tetradecanoic acid 3-diethylamino-1-propanol K: N, N-dibutylaminoethylhexadecanoamide L: Hexadecanoic acid 4-dimethylamino-1-butanol M: N, N-diethylaminopropyl octadecanoamide N: M / 9-octadecenoic acid 2-diethylamido Mixture of ethanol = 1/1 (wt / wt) O: docosanoate 2- dimethyl aminoethanol * 2 in the paint, parts by weight with respect to film forming component 100 parts by weight * 3 T-1: Nippon Bee Chemical Co., Ltd. primer coating R
B-195 Base resin: chlorinated polyolefin Curing agent: None In this case, coating was performed by air spraying so that the dry film thickness was about 10 μm, and drying was performed at 50 ° C. for 10 minutes. T-2: Paint by Nippon Bee Chemical Co., Ltd. R-215 Base resin: Polyester and acrylic Curing agent: Polyisocyanate In this case, the coating is performed by air spraying so that the dry film thickness is about 20 μm, and the drying is about After setting for 10 minutes, it was performed at 80 ° C. for 30 minutes. T-3: Nippon Bee Chemical Co., Ltd. paint R-207 Base resin: Acrylic curing agent: Melamine In this case, the coating is performed by air spraying so that the dry film thickness is about 20 μm, and the drying is set for about 10 minutes. After that, it was performed at 120 ° C. for 30 minutes. * 4 S-1: Corona discharge treatment (Treatment conditions): Apply the applied voltage 3 to the coating film surface of the resin molding.
Corona discharge treatment was performed at 0 KV for 20 seconds. The distance between the electrodes is 1 cm. (High frequency power supply: manufactured by Kasuga Electric
High-frequency power supply device HFS-203) S-2: Corona discharge treatment using high voltage pulse (treatment condition): coating film surface of resin molded body is applied voltage 1
Corona discharge treatment was performed at 90 KV for 20 seconds. The distance between the electrodes is 35 cm. (The corona discharge treatment device of FIG. 1 was used.) * 5 The surface resistance immediately after the corona treatment was measured by using an ultra high resistance meter R8340 type manufactured by Advantest Co.
It measured 1 minute after applying a voltage with V. (Humidity 65
%, Temperature 20 ° C.) * 6 The state of the coating film was visually inspected for skin, gloss, and coating film abnormalities (repelling, dents, color unevenness). ◯: No abnormality X: Abnormality * 7 Impact resistance was measured by applying a shock to the coating surface of the test piece under the conditions of a load of 1 kg and a diameter of the hammer of 1/2 inch using a DuPont impact tester. The drop distance at which the film did not become abnormal was examined. The drop distances and evaluation criteria that do not cause abnormalities in the coating film are as follows.

⊚: excellent (> 50 cm) ◯: good (50 cm) Δ: practically no problem (45 cm) ×: poor (<45 cm) * 8 The film thickness is visually measured by observing the surface of the resin molded body under a microscope. did. * 9 The coating efficiency was calculated by the following formula from the relationship between the weight difference before and after coating and the absolutely dry weight of the discharged coating material.

[Equation 1] * 10 Using a single-edged razor, make 100 goggles at 2 mm intervals on the surface of the electrostatically-coated test piece, and sufficiently adhere the cellophane adhesive tape (JIS Z1522) on it, then peel it off at once in the 90 ° direction and peel it off. I checked the condition.

◯: Not peeled off ×: Peeled off * 11 After the electrostatically coated test piece was immersed in water at 40 ° C for 240 hours, the peeled state was examined by the same method as * 10. ◯: Not peeled off ×: Peeled off

[Table 2] * 1 to * 11: Same as Table 1.

Examples 24 to 29 (Step 1) As shown in Table 3, a paint containing a predetermined amount of the nitrogen-containing compound represented by the general formula (1) was prepared, and the paint was used as a bumper made of polypropylene for automobiles ( Surface resistance;
It was applied to 1.0 × 10 ¹⁶ Ω) and dried, and then the surface was subjected to corona discharge treatment. Immediately, measure the surface resistance of the surface,
The state of the coating film was observed. Furthermore, the impact resistance of the obtained coating film was measured.

(Process 2) Next, the polypropylene bumper for automobiles obtained above is grounded to a static voltage of -40 KV.
Reciprocating stroke 400mm, spraying distance 300m
m, a conveyor speed of 2.2 m / min, a melamine-based paint (R-320, manufactured by Nippon Bee Chemical Co., Ltd.) was electrostatically coated with a coating machine (manufactured by Randsburg Gema, μμBEL30φ).
After drying at 120 ° C. for 30 minutes, the film thickness, coating efficiency and adhesiveness were measured.

Example 30 (Step 1) As shown in Table 3, a coating material containing a predetermined amount of a nitrogen-containing compound represented by the general formula (1) was prepared, and the coating material was added to the polypropylene bumper for automobiles. After electrostatic coating on (surface resistance: 5.2 × 10 ¹¹ Ω) and drying,
The surface was subjected to corona discharge treatment. Immediately, the surface resistance of the surface was measured and the state of the coating film was observed. Furthermore, the impact resistance of the obtained coating film was measured.

Here, the automotive polypropylene bumper containing an additive means an automotive polypropylene bumper containing 0.5% of the nitrogen-containing compound (F) represented by the general formula (1) (surface resistance: 3.1). X10 ¹⁵ Ω) was washed and degreased with isopropyl alcohol and then subjected to corona discharge treatment (S-2).

(Step 2) The same procedure as in Examples 24 to 29 was carried out.

Example 31 (Step 1) As shown in Table 3, a coating material containing a predetermined amount of a nitrogen-containing compound represented by the general formula (1) was prepared, and the coating material was added to the polypropylene bumper for automobiles. After electrostatic coating on (surface resistance; 4.5 × 10 ¹¹ Ω) and drying,
The surface was subjected to corona discharge treatment. Immediately, the surface resistance of the surface was measured and the state of the coating film was observed. Furthermore, the impact resistance of the obtained coating film was measured.

The additive-added automotive polypropylene bumper as used herein means an automotive polypropylene bumper containing 0.5% of the nitrogen-containing compound (I) represented by the general formula (1) (surface resistance: 3.1). X10 ¹⁵ Ω) was subjected to corona discharge treatment (S-2).

(Step 2) The same procedure as in Examples 24 to 29 was carried out.

Comparative Examples 11-14 The same procedure as in Examples 24-29 was carried out.

Next, Examples 24 to 31 and Comparative Examples 11 to 11
The results of 14 are shown in Tables 3 and 4, respectively. As is clear from these tables, in the case of large molded articles such as automobile bumpers, corona discharge treatment using high voltage pulse was confirmed to have excellent effects on coating film physical properties, conductivity and coating efficiency. . Moreover, it was found that the impact resistance of the coating film was excellent in Examples 24 to 31.

[0056]

[Table 3] * 1 to * 11: Same as Table 1.

[0057]

[Table 4] * 1 to * 11: Same as Table 1.

[0058]

According to the present invention, a resin molded product having significantly improved conductivity can be obtained from a resin having low conductivity with high productivity, and electrostatic coating excellent in coating efficiency can be obtained. It is possible to obtain a resin molding having an excellent surface appearance by the electrostatic coating. Further, as an unexpected effect, the impact resistance of the obtained coating film is improved.

Among the resin moldings, it is particularly effective for automobile parts such as bumpers.

[Brief description of drawings]

FIG. 1 is an overall perspective view of a corona discharge treatment device used in an embodiment of the present invention.

FIG. 2 is a circuit diagram showing a circuit configuration of a high voltage pulse generator.

[Explanation of symbols]

 10 Resin Molded Product 20 Counter Electrode 40 Discharge Electrode 60 Dielectric 70 Roller Conveyor 500 High Voltage Pulse Generator

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location B05D 7/24 303 B05D 7/24 303E C08J 7/04 C08J 7/04 D (72) Inventor Miyazoe Shogo 19-17 Ikedanaka-cho, Neyagawa-shi, Osaka Japan Paint Co., Ltd.

Claims (5)

[Claims] 1. A resin molding is coated with a coating material containing a film-forming component and a nitrogen-containing compound represented by the following general formula (1), and the surface of the coating film obtained is subjected to corona discharge treatment. And a method for improving the electrical conductivity of a resin molding. Embedded image 2. The blending amount of the nitrogen-containing compound represented by the general formula (1) is 100 parts by weight of the film-forming component.
The amount is 0.01 to 10 parts by weight.
The described method. 3. The method according to claim 1, wherein the corona discharge treatment is a corona discharge treatment using a high voltage pulse. 4. A coating material having a charge is sprayed and adhered to the coating film of the resin molded product obtained by the method according to claim 1, and electrostatic coating is performed. A method for producing a resin coated article. 5. The method according to claim 1, wherein the resin molded body is an automobile part.