JPH02255872A - Conductive primer composition - Google Patents

Abstract

PURPOSE: To provide a conductive primer compsn. that is improved in electrical conductivity and flexibility, by mixing a pigment, a specified film-forming binder, and a solvent.

CONSTITUTION: A polyester copolymer (a), in an amt. of 40 to 70 wt.% and having an no. average mol.wt. of 800 to 3,500 and an OH value of 50 to 170, comprising an OH-contg. linear segment (i) having an no. average mol.wt. of 300 to 3-000 and an OH value of 15 to 300 and an OH-contg. branched segment (ii), having an no. average mol.wt. of 500 to 2,000 and an OH value of 175 to 300, bonded to the component (i) by esterification of the OH group with a diacid or an anhydride is mixed with 30 to 60 wt.% alkylated melamine formaldehyde crosslinking agent (b) to prepare a film-forming binder (B). A mixture (40 to 75 wt.%) of a pigment (A) contg. a conductive pigment (e.g. conductive carbon black) and the component (B) in a mixing ratio of the component (A) to the component (B) of (5 to 50):100 is mixed with a solvent (C) (e.g. diisobutyl ketone) to prepare the conductive primer compsn. A substrate is coated with this compsn. to obtain a coating which enables the substrate with the coating surface facing outward to be bent at an angle of 180° around a 12.7-mm mandrel, does not substantially create a fracture or a crack in a test at -18°C, and has a surface conductivity of 160 Landsburg units.

COPYRIGHT: (C)1990,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to primer compositions, particularly conductive and flexible Blij-J compositions.

The primer composition is known in the art and published in 198011.
Simon U.S. Patent No. 4.2, issued on May 4th.
It is widely used in the manufacture of automobiles and trucks as shown in No. 32.090. High solids polyester coach 41 fufu compositions are also available in U.S. Patent No. 3.994.851 to Chang, issued November 30, 1976.
It is known as shown in No.

Polyester copolymers having linear and branched chains useful as coatings are shown in U.S. Pat. No. 4,442,269 to Simmerfeld et al., issued April 10, 1984. . However, none of these compositions meet the current requirements of automobile and truck manufacturing plants.

In modern automobile and truck manufacturing facilities, top foot paints are commonly applied by electrostatic spraying, which is not traditionally done. #Electric spraying causes less paint loss and air pollution caused by overspraying of paint. Activate paint*
In order to perform electric spray IJ, the substrate must be conductive. Most automobiles and trucks contain flexible plastic components, and some automobile bodies are made entirely of polymer-reinforced fiberglass, while others are made of plastic. Clearly, these components are not conductive and electrostatic spraying does not work under the best of conditions.

Also, these components are flexible and require flexible primers and top coats. There is a great need in the automobile and truck manufacturing industry for high performance primers that are conductive, flexible, have excellent adhesion to the substrate, and provide a surface to which conventional coatings will adhere.

According to the invention, the pigment to film-forming binder ratio is about 5:100.
~50: 100 film-forming binder and pigment approximately 40-7
5% by weight and a solvent, wherein the pigment is a conductive carbon black pigment and the binder has (1) hydroxyl groups and about 15 to Hydroxyl number of 300 and approx.
a linear segment having a number average molecular weight of 0, a hydroxyl group having a hydroxyl value of about 175-300 and a number average molecular weight of about 500-2000, and a diacid or (2) about 40 to 70% by weight of the binder of a polyester copolymer having branched segments attached to the linear segments by esterification with an anhydride; and (2) about 70% by weight of the alkylated melamine formaldehyde crosslinker. 30 to 60% by weight, and the composition forms a flexible coating on the substrate such that the coated substrate has a 1/2 in. Can be bent 180' around the
and wherein the coating exhibits substantially no fissures or 1i cracks when tested at -18°C and wherein the coating has a surface conductivity of at least 160 Randsburg units.

The primer compositions of the present invention are hard, flexible and conductive and can be applied to substrates such as cold rolled steel, phosphated steel, polyester reinforced glass fibers, reaction injection molded urethanes, partially crystalline polyamides and other plastic substrates. various substrates
Forms a finish with excellent adhesion and provides a surface to which the base coat will adhere. The primer of the present invention is advantageous because the resulting finish is conductive and can be applied with Totsubuko I by electrostatic spraying, which is currently used in many automotive and i-rack manufacturing facilities. Particularly useful on plus-f disk substrates.

The visibility of the finish is approximately 0.0
After keeping the panel coated with 254m+* (1,0 mil) fully cured film at -18°C, the diameter of 12
．． It is determined by a mandrel bend test in which the coated side of the panel is bent toward the t-side around a 7 mm (1/2 in) steel mandrel. Coach ink must not show any cracks or cracks.

The surface conductivity of the coating composition was determined by the Randsburg Electrocoating Corporation, Indianapolis, Indiana, USA.
Electroeoating Corporation
Sprayability meter (5 prayab) made by n)
It is measured with ilth yMeter). The compositions of the present invention have at least 160 Ransburg
l) ur g) units, preferably 165 to 350
It has a surface conductivity in Randsburg units.

The primer composition of the present invention is about 40-75! Corresponding to a film-forming binder content of approximately 25% to 60% by weight of a liquid carrier, which is usually a solvent for the binder. The composition includes pigment in a pigment to binder weight ratio of about 5:100 to 50:100. The pigment must contain a conductive pigment, such as a conductive carbon black pigment. Other pigments can also be used in the compositions of the invention.

Preferably, the film-forming binder of the composition comprises about 50 to 80% by weight polyester copolymer and about 20 to 50% by weight alkylated melamine formyldehyde crosslinker.
One highly preferred composition contains about 60 to 70 weight percent polyester copolymer and uses 30 to 401 weight percent bulking agent to form a high performance composition.

The polyester copolymer used in the composition has linear polyester segments and branched polyester segments having hydroxyl groups and having a hydroxyl number of about 15-300 and a number average molecular weight of about 300-3000. These branch segments have hydroxyl groups and have hydroxyl numbers of about 175-300 and about 500-300.
It has a number average molecular weight of 2000 and is bonded to a linear segment by nitridation of the hydroxyl groups of the two segments with a diacid or anhydride.

The polyester copolymers have a number average molecular weight of about 800-3500 and a human o,'F syl number of about 50-170.

Molecular weight was determined by Luker hermation chromatography using polytutyacrylic acid and methyl as standards.)
It is measured in

References herein and 1. ．． U.S. Pat. No. 4,442,269 to Simmerfeld et al., incorporated herein by reference, discloses a method for making the polyester copolymers used in the present invention. Also discussed are preferred polygostyl compositions.

Linear segments are made of linear diols and dicarboxylic acids. Typical diols that are useful have 2 to 10 carbon atoms, such as ethylene glycol, propylene gelol, butanediol, bentanediol, neobentyl glycol, hexanediol, octanediol,
Nisderdiol (Esterdiol) 204 (
-L Union Ca, rbide
) commercially available diol]. The preferred diol is neopentyl glycol, because it forms a high-performance polyester! -1,6-hexanediol.

Typical dicarboxylic acids that can be used are aromatic acids such as phthalic acid, orthophthalic acid, isophthalic acid, and aliphatic acids such as adipic acid, azelaic acid, etc.

Branched segments are made of linear diols, branched polyols and dicarboxylic acids. The linear diols and dicarboxylic acids mentioned above are used. Typical branched polyols that can be used are trimethylolpropane, trimethylolpropane, pentaerythritol, and the like.

The linear and branched segments are joined by esterification of the hydroxyl groups of each segment with a diacid or anhydride. The acids mentioned above can be used, but preferably the anhydrides are used. Typical anhydrides include orthophthalic anhydride, succinic anhydride, glutaric anhydride, and the like.

One preferred polyester copolymer is a linear segment of a polyester of neopentyl glycol, hexanediol, isophthalic acid, and azelaic acid) and a branched chain segment of a polyester of neopentyl glycol, glycol, trimethylolpropane, isophthalic acid, and azelaic acid. and is esterified with ortho-7-talic anhydride. The molar ratio of linear chain segment/anhydride/branched chain segment is l/l/1 and the copolymer has about 800-150
It has a number average molecular weight of 0 and a hydroxyl number of 125 to 1.55.

Polyester segments and polyester copolymers are
Manufactured by the usual esterification method in which the components are charged into a polymerization vessel together with a solvent and a normal J esterification catalyst, and heated to about 100-200℃ for about 30 minutes to 5 hours while removing water generated during the process. be done.

The crosslinking agent used in the composition is an alkylated melamine formaldehyde crosslinking resin. Typically, these resins contain 1 to 8 carbon atoms in the argyl group. To produce high-performance primers, Cymel
One preferred combination is methylated melamine formaldehyde resins such as ``Cyn+el'' 380 and methylated melamine formaldehyde resins containing methoxymethylimino groups such as ``Cyn+el'' 325.
About 60-40% by weight of Cymel 380 corresponds to 0-641% of Cymel 380.
)"325.

The composition includes a conductive carbon black pigment, such as a conductive furnace black pigment. One preferred pigment is Vulcan XC-, which has no surface treatment.
72-R7 Arnes Black pigment. Other pigments are
The electrical conductivity is at least 160 Randsb.
It can be used in the composition provided that urg) units remain. Typical pigments that can be used are filler pigments such as talc, chinaclaverite, carbonates, silicates, metal oxides such as titanium dioxide, zinc oxide, iron oxide, and organic color pigments and dyes.

Pigments are made by sand grinding.
into the primer composition by first forming a millbase with the polyester copolymer or another compatible polymer or dispersant by conventional techniques such as milling, ball milling, attritor milling, or two-roll milling. can do. This millbase is blended with other ingredients used in the composition.

Any conventional solvent or solvent binder can be used in preparing the primer composition, provided that the polymeric binder components are compatible and the solvent is selected to provide a high performance primer. . The following are examples of solvents that can be used to prepare the compositions. Methyl ethyl ketone, methyl ethyl ketone, methyl isobutyl ketone, toluene, xylene, acetone, 1 ethylene glycol monobutyl ether acetate and other esters, ethers, ketones and commonly used aliphatic and aromatic hydrocarbon solvents.

The composition is about 101-2% by weight based on the weight of the binder.
UV light stabilizers (this term includes UV absorbers, screening agents and quenchers). Typical UV stabilizers include benzophenones, l-lyazine, triazoles, benzoates, hindered amines, and blends thereof.

The primer composition of the present invention can be applied to flexible or rigid substrates by conventional methods such as spraying, electrostatic spraying, dipping, brushing, flow coating, and the like. As in duplication, the preferred method is electrostatic spraying. After application, the composition is baked at about 100-200°C for about 5-45 minutes to form a primer coating layer about 0.1-240 mils thick. Generally, the primer layer is about 0.0127 to 0.0381y thick
am (0.5-1.5 mil). Conventional solvent-based or water-based acrylic enamels or lacquers such as acrylic polyurethane coatings, polyester urethane coatings, alkyd enamels, etc. can be applied and then baked to form a durable automotive or truck finish on the substrate.

The present invention will be explained below with reference to Examples. Unless otherwise specified,
All parts and percentages are by weight.

Molecular weight is determined by gel permeation chromatography using polymethyl methacrylate as standard.

EXAMPLE A polyester solution is prepared by charging the following ingredients into a polymerization vessel equipped with a mechanical stirrer, an electric heating mantle, a nitrogen inlet tube, a water separator, a thermometer, a cylinder funnel, and a water-cooled reflux condenser.

Part by weight (1 minute xylene solution) Orthophthalic anhydride 62.53 parts 2 xylene 7.20 parts 3 xylene 20.00 parts 4 Methyl ethyl ketone 75.08 Total 938.25 parts 1 was charged into a polymerization vessel, and while stirring, approx. 1 hour 125
Heat to ~150°C. Then add part 2, about 220 ~
Water is distilled off at a temperature of 225°C. Add portion 3, then portion 4, and cool the composition to room temperature. The resulting polyester solution has a solids content of about 80% and the polynisdel has a hydroxyl number of about i20-150 and a
and a molar ratio of branched polyester/orthophthalic anhydride/linear polyester of 1:1:1.

Place the following ingredients in a sand mill and grind 0-0127m (
Prepare a portion of the xylene solution by grinding to a fineness of 0-5 mil).

Polyester solution (prepared above) 40.01 parts by weight Inbutanol solution) Polyester solution (prepared above) 13.89 parts by weight Melamine formaldehyde resin (80% solids in isobutanol solution) Diisodityl ketone 26 .73 Methyl Ethyl Ketone 1.1.46 Total 100.00 The following ingredients were blended together to prepare a coating composition.

Mill base (prepared above) Parts by weight 56.08 "Resiflow" [50% Sol-v of acrylic terpolymer flow control agent]
esso)”100 solution] 0.26 “10% xylene solution of Syloid 378 (synthetic silica matting agent with a particle size of 0.97 from 3 to 5M)] Ethyl]/glycol monobuboole-7 Acetate I 4°38 Butanol 8.04 Total 101.89 The resulting primer composition had a solids content of 46.5%;
The pigment/binder ratio is 13.5/100 and the color is black.

This primer was sprayed with methyl amyl ketone at 25°C to reduce the viscosity to 35' as measured in No. , reaction injection molded urethane panels, sprayed onto partially crystalline polyamide panels. The steel panel is baked at approximately 125℃ for 30 minutes,
The remaining panels were baked at 120'C for 30 minutes.

The panels were black in color and had a dry film thickness of about 1020102O32.8 mils) and a gloss of about 30 as measured at 60°C.

The coating on the panel had the following properties.

Scratch Resistance - Good Adhesion - Good Sandability - Good Knife Scratch Resistance Good Solvent Resistance - 75 double rubs (1: 1 Jtp - Naphtha/Imp "1 Bar Conductivity ---> 165 Ransburg units Humidity resistance 96 hours at 38°C/100% relative humidity - 10' Rodry substrate test (crossbub ~ and tape adhesion 1
Day 0 1 Mandrel bending 180' (-18°c) 5t
21 (-29℃), 41+ grade system (
1) 0-10. 10-best, 0-J' bad (2)
0-5, 5-best, 0-worst The present invention has been described in detail, and the present invention can be further summarized by the following embodiments.

l) Pigment to film-forming binder ratio of about 5:too to 50:10
40 to 75% by weight of a pigment and a solvent, the pigment consisting of a conductive carbon black pigment and the binder essentially having (1) hydroxyl groups; 1- and having a human l fugicyl value of about 15-300 and a number average molecular weight of about 300-3000, and a linear segment having hydroxyl groups and having a hydroxyl z1-value of about 175-300 and a hydroxyl z1-value of about 500-2.
Based on the weight of the binder of a polyester copolymer having a number average molecular weight of 5,000 and branched chain segments that are bonded to linear segments by esterification of the hydroxyl groups with a diacid or anhydride. (2) about 30 to 60% by weight of an alkylated melamine formaldehyde crosslinker, and the composition forms a hard flexible coating on the substrate coated thereby. The substrate can be bent 180' around a 12.7 m + m (1/2 in) mandrel with the coated side outside and at -18°C.
A primer composition in which the coating exhibits substantially no fissures or cracks when tested at 100 mL and wherein the coating has a surface conductivity of at least 160 Ransburg units.

2) The coating composition according to 1) above, wherein the coating has a surface conductivity of 165 to 350 Landsburg units.

3) The linear chain of polygostyl is neopentyl glycol,
The coating composition according to 2) above, which comprises hexanediol, isophthalic acid and azelaic acid.

4) Coating group I according to 3) above, wherein the branched chain segment of the polyester comprises neopentyl glycol, trimethylolpropane, isophthalic acid and azelaic acid.
T thing.

5) The coating composition according to 4) above, wherein the anhydride is orthophthalic anhydride.

6) The coating composition according to 1) above, wherein the alkylated melamine formaldehyde crosslinking agent is a blend of a methylated melamine formaldehyde resin containing an alkoxyimino group or a methylated melamine formaldehyde resin.

7) The coating composition of 1) above, comprising about 0.701 to 2% by weight of UV stabilizer, based on the weight of the binder.

8) About 50-80% by weight of polyester copolymer based on the weight of the binder and about 20-5% by weight of the binder.
% of an alkylated melamine formaldehyde crosslinking agent.

9) The coating composition according to 8) above, wherein the alkylated melamine formaldehyde crosslinking agent essentially consists of a blend of a methylated melamine formaldehyde resin having methoxymethylimino groups and a methylated melamine formaldehyde resin.

10) Polyester copolymers having essentially (1) linear segments of neopentyl glycol, hexanediol, isophthalic acid, and azelaic acid and branched chain segments of neopentyl glycol, trimethylolpropane, isophthalic acid, and azelaic acid. about 60- by weight of the binder of a polyester copolymer having a number average molecular weight of about 800-3500 and a hydroxyl number of about 50-170.
(2) methylated melamine formaldehyde resin containing methoxymethylimino groups of about 40 to 60% by weight based on the weight of the crosslinking agent and 60 to 40% by weight of the methylated melamine based on the weight of the crosslinking agent. The alkylated melamine formaldehyde crosslinking agent comprising a formaldehyde resin contains about 30 to 40% by weight of the binder, based on the weight of the binder, and the coating is 165 to 3
The coating composition according to item l) above, having a surface conductivity of 50 Landsburg units.

11) A flexible substrate coated with a dried, cured layer of the composition described in 1) above.

12) The above where the board is plastic! The flexible substrate described in

The flexible substrate according to 11) above, wherein the substrate is reinforced with glass fiber and 1=polyester.

Partially crystalline polyamide 11) above, which is a hard resin. Visibility substrate as described.

Claims (1)

[Claims] 1) The ratio of pigment to film-forming binder is about 5:100 to 50:10.
0 film-forming binder and about 40 to 75% by weight of a pigment and a solvent, the pigment comprising a conductive carbon black pigment and the binder essentially having (1) hydroxyl groups; and a linear segment having a hydroxyl number of about 15 to 300 and a number average molecular weight of about 300 to 3000;
Polyesters having a hydroxyl number of 75 to 300 and a number average molecular weight of about 500 to 2000 and having branched chain segments attached to linear segments by esterification of the hydroxyl groups with diacids or anhydrides. (2) about 30 to 60% by weight of an alkylated melamine formaldehyde crosslinker, based on the weight of the copolymer binder, and the composition forms a hard flexible coating on the substrate. so that the coated substrate can be bent 180° around a 12.7 mm (1/2 in) mandrel with the coated side outward and the coating will not tear or crack when tested at -18°C. A primer composition having substantially no surface conductivity and the coating having a surface conductivity of at least 160 Landsburg units. 2) Polyester copolymers having essentially (1) linear segments of neopentyl glycol, hexanediol, isophthalic acid, and azelaic acid and branched chain segments of neopentyl glycol, trimethylolpropane, isophthalic acid, and azelaic acid. from about 60 to about 60, based on the weight of the binder, of a polyester copolymer having a number average molecular weight of about 800 to 3,500 and a hydroxyl number of about 50 to 170.
(2) methylated melamine formaldehyde resin containing methoxymethylimino groups at about 40-60% by weight based on the weight of the crosslinking agent and 60-40% by weight methylated melamine formaldehyde based on the weight of the crosslinking agent. about 30% to 40% by weight of the binder, based on the weight of the binder of the blend of alkylated melamine formaldehyde crosslinking agent comprising a resin, and the coating comprises 165% to 30% by weight of the binder.
The coating composition of claim 1 having a surface conductivity of 50 Landsburg units. 3) A flexible substrate coated with a dry, cured layer of the composition of claim 1.