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WO1990008846A1 - Bains d'electrodeposition cathodique d'aminoplaste a faible polymerisation - Google Patents

Bains d'electrodeposition cathodique d'aminoplaste a faible polymerisation Download PDF

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Publication number
WO1990008846A1
WO1990008846A1 PCT/US1989/004932 US8904932W WO9008846A1 WO 1990008846 A1 WO1990008846 A1 WO 1990008846A1 US 8904932 W US8904932 W US 8904932W WO 9008846 A1 WO9008846 A1 WO 9008846A1
Authority
WO
WIPO (PCT)
Prior art keywords
resin
crosslinker
cathodic
cathodic electrodepositable
electrodepositable resin
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/US1989/004932
Other languages
English (en)
Inventor
Edward Chu
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
EIDP Inc
Original Assignee
EI Du Pont de Nemours and Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by EI Du Pont de Nemours and Co filed Critical EI Du Pont de Nemours and Co
Publication of WO1990008846A1 publication Critical patent/WO1990008846A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
    • C09D5/44—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes for electrophoretic applications
    • C09D5/4419—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes for electrophoretic applications with polymers obtained otherwise than by polymerisation reactions only involving carbon-to-carbon unsaturated bonds
    • C09D5/443—Polyepoxides
    • C09D5/4457—Polyepoxides containing special additives, e.g. pigments, polymeric particles
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D163/00—Coating compositions based on epoxy resins; Coating compositions based on derivatives of epoxy resins
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
    • C09D5/44—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes for electrophoretic applications
    • C09D5/4419—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes for electrophoretic applications with polymers obtained otherwise than by polymerisation reactions only involving carbon-to-carbon unsaturated bonds
    • C09D5/443—Polyepoxides
    • C09D5/4453—Polyepoxides characterised by the nature of the curing agent

Definitions

  • the field of art to which this invention pertains is electrodepositable compositions containing aminoplast resins with metal catalysts to be used in cathodic electrocoat processes .
  • electrodeposition is widely used in the automotive industry to apply primers to automotive substrates).
  • a conductive article is immersed as one electrode in a coating composition made from an aqueous emulsion of film-forming polymer.
  • An electric current is passed between the article and a
  • the article to be coated typically serves as the cathode in the electrical circuit with the counter-electrode being the anode.
  • Resin compositions used in cathodic electrodeposition baths are also well known in the art. These resins are usually manufactured from polyepoxide resins which have been chain extended and adducted to include a nitrogen atom. The nitrogen is typically introduced through reaction with an amine compound. Normally these resins are blended with a crosslinking agent and then salted with an acid to form a water emulsion which is usually referred to as a principal emulsion.
  • the principal emulsion is combined with a pigment paste, coalescent solvents, water, and other additives to form the electrodeposition bath.
  • the electrodeposition bath is placed in an insulated tank containing the anode.
  • the article to be coated is made the cathode and is passed through the tank containing the electrodeposition bath.
  • the thickness of the coating is a function of the bath characteristics, the electrical operating characteristics, the immersion time, and so forth.
  • the coated object is removed from the bath after a fixed period of time (normally about two or three minutes).
  • the object is rinsed with deionized water and the coating is cured, typically in an oven at sufficient temperature to produce crosslinking.
  • compositions used amine salt group-containing resins or onium salt group-containing resins as the binder, see, for example, U.S. Pat. No. 3,454,482 to Spoor et al and U.S. Pat. No. 3,839,252 to Bosso and Wismer.
  • the curing agents for these resins were usually aminoplasts since these curing agents were used quite successfully with the earlier anodic electrodepositable resins.
  • electrodeposited coating is basic and relatively high temperatures, that is, about 400oF (204oC) or higher must be used for complete curing of the cathodically electrodeposited coating.
  • Patent 4,501,833 also discloses quaternary onium salt containing resins in combination with high imino functional aminoplasts. While the '833 patent
  • an aminoplast system will cure at low temperatures (100oC to 150oC) in a basic environment (i.e. cathodic system) if catalyzed by metal catalysts.
  • the metal catalysts are metal salts of both organic acid salts or inorganic acid salts such as Cu, Fe, Mn, Co, Pb, Bi, Zn and Sn octoate and napthanate. As stated above, this result is very surprising, as it was previously thought that aminoplast resins would only cure in an acid environment at these relatively low temperatures.
  • Metal catalysts are known in the art to catalyze certain coating compositions but metal
  • Patent 4,644,036 ; and in electrocoat systems for amidation (U.S. Patent 4,477,530). There is nothing in the prior art to suggest their use to catalyze the reaction of aminoplast resins.
  • novel resin of this invention is not restricted to cathodic electrodeposition. It also could be used in non-electrocoat applications such as spray applications, roller coating, dip applications, and so forth.
  • a novel, improved cathodic electrodeposition coating composition is disclosed using aminoplast resins. More specifically, our coating composition comprises a typical polyepoxy resin with primary or secondary amino functionality crosslinked with aminoplasts
  • novel composition provides a smooth coating with good top coat adhesion and corrosion resistance which will cure at 100oC to 150oC.
  • the amino functional backbone resin which is used in the practice of this invention is 'typically obtained by reacting polyepoxide resins with nitrogen containing compounds such that the resin becomes amino functional.
  • the resin should contain either primary or secondary amino functionality and most preferably primary amino functionality.
  • the polyepoxide resins which are used to make the amino functional resins are well known in the art.
  • the polyepoxide resins which are used in the practice of the invention are polymers having a
  • the preferred polyepoxides are polyglycidyl ethers of cyclic polyols. Particularly preferred are
  • polyglycidyl ethers of polyhydric phenols such as bisphenol A. These polyepoxides can be produced by etherification of polyhydric phenols with epihalohydrin or dihalohydrin such as epichlorohydrin or
  • cyclic polyols can be used in preparing the polyglycidyl ethers of cyclic polyol derivatives.
  • examples of other cyclic polyols would be alicyclic polyols, particularly cycloaliphatic polyols, such as 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1.2-bis (hydroxymethyl) cyclohexane, 1,3-bis-(hydroxymethyl) cyclohexane and hydrogenated bisphenol A.
  • the polyepoxides have number average
  • Mn molecular weights
  • the polyepoxides are preferably chain extended with a polyether or a polyester polyol which increases rupture voltage of the composition and
  • polyether polyols and conditions for chain extension are examples of polyether polyols and conditions for chain extension.
  • polyester polyols for chain extension are disclosed in U.S. Pat. No. 4,148,772, column 4, line 42, to column 5, lines 53, the portions of which are hereby
  • this invention would also be applicable to acrylic, polybutadiene, polyester or phenolic resins which contain amino functionality.
  • the backbone resin is given its amino
  • the primary amino functionality can be imparted by the ketimine approach as shown by U.S. Patent No. 4,104,147 or the
  • amino functionality on the backbone resin is primary amino or secondary amino functionality. Most preferably the amino functionality is primary.
  • the ketimine approach appears to be the most prefered method of imparting the amino
  • the crosslinkers in this invention are aminoplast resins. These resins are partially or fully alkylated melamine-formaldehyde compounds which are commercially available. For example, the materials are available from the Monsanto Company under the trademark Resimene ® and from American Cyanamid under the
  • Cymel ® These resins are chosen according to the degree of alkylation desired. Our preferred aminoplast is one which contains high imino groups such as Cymel ® 1158. It is also possible to use partially alkylated resins containing methyol groups such as Cymel ® 373 or Cymel ® 380. Less preferred are highly alkylated aminoplasts such as Cymel ® 300 and Cymel ®
  • carboxyl modified amino resins such as the Cymel ® 1100 resins (specifically Cymel ® 1141 and Cymel ® 1125) could be utilized in the invention.
  • urea-formaldehyde resins Another type of aminoplast resin which can be used as the crosslinker are urea-formaldehyde resins. These resins are commercially available from American Cynamide Co. under the tradename Beetle ® . These resins are also chosen according to the degree of alkylation desired.
  • the preferred urea-formaldehyde resins are ones which contains methylol groups such as Beetle ® 55, 60, or 65. Less preferred are urea-formaldehyde resins which are highly alkylated such as Beetle ® 80.
  • the metal catalysts of our invention are metal salts of both organic acids or inorganic acids, or coordination compounds of these metals.
  • Organic acid salts are more desirable, particularly organic acid salts that are compatible with the resin compositions and that are water insoluble. These usually are
  • the metals used in the catalyst are iron, lead,lithium, potassium, sodium, calcium, magnesium, beryllium, aluminum, zinc, cadmium, barium, scandium, gallium, indium, tin, vanadium, manganese, molybdenum, tellurium, silver, copper, nickel, cobalt, chromium, palladium and so forth.
  • Our preferred catalysts are Co, Cu, Fe and Pb octoates or napthenates. These catalysts are
  • the amine functional resin and the aminoplast crosslinker are the principal resinous ingredients in the electrocoating composition. They are usually present in a ratio of backbone resin to crosslinker of about 40/60 to 95/5 percent by weight of solids.
  • the ratio is 85/15 to 65/35 backbone resin to crosslinker.
  • the metal catalyst is typically present in amounts of about 0.1 to 5.0 percent by weight of total resin solids. Preferably, the metal catalyst is present from 0.5 to 1.5 percent by weight of total resin solids.
  • the electrocoating compositions usually contain a pigment which is incorporated into the composition in the form of a paste.
  • the pigment paste is prepared by grinding or dispersing a pigment into a grinding vehicle and optional ingredients such as wetting agents, surfactants and defoamers.
  • Pigment grinding vehicles are well known in the art. After grinding, the particle size of the pigment should be as small as practical, generally a Hegman grinding gauge of about 6 to 8 is usually employed.
  • the pigment-to-resin weight ratio is also fairly important and should be preferably less than 0.5:1, more preferably less than 0.4:1, and usually about 0.2 to 0.4:1. Higher pigment-to-resin solids weight ratios have also been found to adversely affect coalescence and flow.
  • the coating composition of the invention can contain optional ingredients such as plasticizers, wetting agents, surfactants, defoamers and so forth.
  • optional ingredients such as plasticizers, wetting agents, surfactants, defoamers and so forth.
  • surfactants and wetting agents include alkyl imidazolines such as those available from
  • ingredients when present, constitute from about 0 to 20 percent by weight of total resin solids.
  • Plasticizers are preferred optional ingredients because they promote flow. Examples are high boiling water immiscible materials such as ethylene or propylene oxide adducts of nonyl phenols or bisphenol A. When plasticizers are used, they are used in amounts of about 0.5 to 10.0 percent by weight of total resin solids.
  • the electrodepositable coating compositions of the present invention are dispersed in aqueous medium.
  • the term "dispersion" as used within the context of the present invention is believed to be a two-phase translucent or opaque aqueous resinous system in which the resin is in the dispersed phase and water the continuous phase.
  • the average particle size diameter of the resinous phase is about 0.1 to 5.0 microns, preferably less than 1 micron.
  • concentration of the resinous products in the aqueous medium is, in general, not critical, but ordinarily the major portion of the aqueous dispersion is water.
  • the aqueous dispersion usually contains from about 3 to 75, typically 5 to 50 percent by weight of total resin solids.
  • Aqueous resin concentrates which are to be further diluted with water at the job site generally range from 30 to 75 percent by weight of total resin solids. Fully diluted electrodeposition baths
  • resin solids content of about 3 to 25 percent by weight of total resin solids.
  • the aqueous medium may also contain a coalescing solvent.
  • Useful coalescing solvents include hydrocarbons, alcohols, esters, ethers and ketones.
  • the preferred coalescing solvents include alcohols, polyols and ketones.
  • Specific coalescing solvents include butanol, 2-ethylhexanol,
  • the amount of coalescing solvent is not unduly critical and is generally between about 0 to 15 percent by weight, preferably about 0.5 to 5 percent by weight based on total weight of the aqueous medium.
  • methyisobutylketone was stripped off and the batch was cooled to 50oC under a dry N 2 gas blanket and was packaged to be used in part (B).
  • This product has a total amine equivalent of about 128.9 at 72.0 percent solids with amine functionality of two.
  • a primary amine containing resin was prepared from the following ingredients:
  • MIBK Methyisobutylketone
  • MIBK (third portion) 361.
  • Epoxy resin from Dow Chemical Co. formed from reacting epichlorohydrin and bisphenol A having epoxy equivalent of 195.
  • the batch was held at 150oC for about two hours until the milliequivalent of combined amine and epoxy per gram solution was equal or less than 0.2.
  • the batch was cooled to 120oC and then the
  • TABLE 1 shows the formulation of the amino epoxy resin using various aminoplasts with or without metal catalysts incorporated.
  • TABLE 2 shows the solvent resistance of the draw down film from the formulations from TABLE 1 on cold roll steel and zinc phosphatized steel substrates at various bake temperatures. (A coating of film which withstands 100 MEK double rubs is considered cured). In all cases the formulations that contain metal catalysts cure much better than those without the metal catalyst. The cure temperature is significantly lower.
  • the cure temperature in all cases has also been significantly reduced when an appropriate metal catalyst is utilized versus the same system without a metal catalyst.
  • the cure film of either system above has also exhibited good solvent resistance and good adhesion to metal.
  • Formulation No.2 from Table I can be made into a cathodic dispersion as follows:
  • the amino epoxy resin, Cymel ® 1158, Synfac 8029 ® , lead octoate and formic acid were premixed in a container equipped with an agitator for one-half hour. Then the deionized water was very slowly introduced with good agitation until the mixture was inverted or emulsified to aqueous dispersion.
  • the initial pH was about 7.5 with a conductivity of about 2.8 micro-mHOs per cm.
  • the cured film did not soften after 100 MEK double rubs. It has good wet adhesion to metal and good corrosion resistance with a creepage of 1 mm after

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  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Wood Science & Technology (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Health & Medical Sciences (AREA)
  • Molecular Biology (AREA)
  • Paints Or Removers (AREA)
  • Phenolic Resins Or Amino Resins (AREA)
  • Compositions Of Macromolecular Compounds (AREA)

Abstract

L'invention concerne une résine à électrodéposition cathodique à faible polymérisation. Le squelette de la résine est un additif d'amine polyépoxyde réticulé avec des résines carbamide et catalysé à l'aide de catalyseurs métalliques. Ladite résine peut se polymériser dans un environnement basique à une température inférieure à 150°C. On peut saler ladite résine avec un acide et on peut la dissoudre ou la disperser dans de l'eau. On peut ensuite formuler les dispersions aqueuses en revêtements servant de couche d'apprêt électrochimique pour des objects métalliques.
PCT/US1989/004932 1989-01-26 1989-11-13 Bains d'electrodeposition cathodique d'aminoplaste a faible polymerisation Ceased WO1990008846A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US30147289A 1989-01-26 1989-01-26
US301,472 1989-01-26

Publications (1)

Publication Number Publication Date
WO1990008846A1 true WO1990008846A1 (fr) 1990-08-09

Family

ID=23163529

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1989/004932 Ceased WO1990008846A1 (fr) 1989-01-26 1989-11-13 Bains d'electrodeposition cathodique d'aminoplaste a faible polymerisation

Country Status (4)

Country Link
CA (1) CA2007991A1 (fr)
ES (1) ES2028503A6 (fr)
MX (1) MX170447B (fr)
WO (1) WO1990008846A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0488934A3 (en) * 1990-11-29 1993-03-17 Bayer Ag Binder and a method for the preparation of a coating
US11426762B2 (en) 2015-12-31 2022-08-30 Henkel Ag & Co. Kgaa Low bake autodeposition coatings

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3937679A (en) * 1968-10-31 1976-02-10 Ppg Industries, Inc. Electrodepositable compositions
US4385097A (en) * 1977-11-02 1983-05-24 Kansai Paint Co., Ltd. Anticorrosive coating composition
US4560717A (en) * 1984-07-03 1985-12-24 Ppg Industries, Inc. Cationic electrodepositable compositions containing formaldehyde scavenger
US4617331A (en) * 1983-10-17 1986-10-14 Ppg Industries, Inc. Water-dispersible polymers containing metal chelating groups
US4647604A (en) * 1984-06-16 1987-03-03 Basf Aktiengesellschaft Heat-curable coating agent and its use

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3937679A (en) * 1968-10-31 1976-02-10 Ppg Industries, Inc. Electrodepositable compositions
US4385097A (en) * 1977-11-02 1983-05-24 Kansai Paint Co., Ltd. Anticorrosive coating composition
US4617331A (en) * 1983-10-17 1986-10-14 Ppg Industries, Inc. Water-dispersible polymers containing metal chelating groups
US4647604A (en) * 1984-06-16 1987-03-03 Basf Aktiengesellschaft Heat-curable coating agent and its use
US4560717A (en) * 1984-07-03 1985-12-24 Ppg Industries, Inc. Cationic electrodepositable compositions containing formaldehyde scavenger

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0488934A3 (en) * 1990-11-29 1993-03-17 Bayer Ag Binder and a method for the preparation of a coating
US11426762B2 (en) 2015-12-31 2022-08-30 Henkel Ag & Co. Kgaa Low bake autodeposition coatings

Also Published As

Publication number Publication date
CA2007991A1 (fr) 1990-07-26
ES2028503A6 (es) 1992-07-01
MX170447B (es) 1993-08-23

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