DE2345044A1 - POLYMER COMPOSITION FOR CATHODIC ELECTROPHORETIC DEPOSITION - Google Patents

Description

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M&T CHEMICALS INC., Greenwich, Conn./V.St.A.

"Polymer Composition for Cathodic Electrophoretic Deposition"

Priority : September 6, 1972, V.St.A.

The invention relates to new compositions that are suitable for the production of cathodically electrophoretically deposited coatings, 'on the production of such. Compositions and methods of making articles in which at least a portion is a Has cathodically electrophoretically deposited coating.

It is known that various organic covering materials are dispersed in an aqueous medium and based on electrophoresis Paths are deposited on a conductive object that is immersed in an aqueous medium can. At dor her'jiomuiliohen electrophorotic Gn Boschich-

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tung practice is a color on an anode deposited · In addition to one or more ionically charged resins can the color pigments, extenders, and optionally also an additive which causes crosslinking of the resin, included- The coated article is then removed from the bath, whereupon crosslinking or curing is caused by the application of a high temperature. The hardening can take place either through an oxidative polymerization of unsaturated groups (in the case of a single resin system) or through the reaction of a crosslinking additive with functional groups present in the resin. Anodic deposition is more beneficial if a crosslinking additive is used, since the acidity developed at the anode catalyzes this reaction.

However, a snodische deposition of organic deposits has the disadvantage that metal ions are set free, caused by the electrolytic oxidation of the substrate. These ions contaminate the base by becoming trapped in the base resin . The oxidation process also promotes corrosion of the substrate metal. It has now been found that cathodic deposits can be used to overcome these disadvantages . The advantages of the cathodic deposition were not yet fully used, since the current technology does not erlsubt cure polymers using conventional cross-linking additives, ds no acid present to kstelysieren the reaction of these additives with the electrodeposited polymer.

The aim of the invention is to provide mensetzungen of new Harzzusem suitable for the production of cathodic electrodeposition coated articles "Another object of the invention to provide a new

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cathodic resin, which when dispersed in an aqueous hedium and exposed to an electrical voltage is deposited on a suitable cathode immersed in the aqueous medium, wherein a adhesive film is formed, which is then transformed into a permanent, chemically resistant film by heating Covering can be hardened. Another object of the invention is to provide an improved method of making cathodically deposited films.

The electrophoretic covering masses according to the invention are crosslinkable aqueous polymer compositions that contain:

1) an 8-min-containing polymer, at least a portion of the amine groups being present as the ammonium salt of an organic acid, with the restriction that the repeating units containing the amine groups make up between 2 and 50 % of the repeating units present in the polymer; and

2) a substantially non-crosslinked condensation product that is at least partially from formaldehyde and a phenol or a suitably substituted aromatic hydrocarbon, the condensation product on the average at least two methylol radicals per molecule has;

where the weight ratio of component 1 to component 2 is between 1: 9 and 9 "· 1 '.

A · The amine-containing polymer .

Amine-containing organic resin compositions suitable for Cathodic electrodeposition can be useful by addition polymerization of a mixture of unsaturated monomers which are 2 to 50 mol # one Amine compound obtained. This supply

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Compositions can also by condensation polymerization of di- or tribasic organic acids with polyfunctional amines or hydroxyamines are produced.

The amino radical on the polymer is preferably primary or secondary, which fulfills at least two important functions:

1) It gives the polymer a cationic charge when neutralized with an acid.

2) Due to the active hydrogen em nitrogen atom it also becomes a place of attachment when the coating containing the formaldehyde condensation product passes through Heating to an elevated temperature is cured as described below.

If tertiary amino radicals are present, desrin should be Polymer between 2 and 50 mole # repeat units that contain functional groups that have active hydrogen atoms that lead to a reaction are capable with the formaldehyde condensation product · Examples of suitable radicals are hydroxyl and Carboxyl radicals.

Typical amine compounds which are suitable for addition copolymerization are emine-containing esters of monofunctional unsaturated acids of the formula

HoG OR ^{4 2} \, Il I

H ₂ C

and amine-containing amides of the formula

R ¹ N-R ^ - O E ⁴ Il I. 0 -C -C =

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1 U-

R ¹ OE ⁴

\ 3 1 ^Μ -

N-lr-NCG »GH _o

R ^

1
wherein R is an alkyl, alicyclic or aryl group (preferably having 1 to 12 carbon atoms); R preferably represents hydrogen or an alkyl, alicyclic or aryl group (preferably having 1 to 12 carbon atoms); R ^ is - (CH ^) -, where η has a value from 1 to 6; R represents an alkyl group (preferably having 1 to 8 carbon atoms) or hydrogen. Examples of such materials are acrylic or methacrylic esters of t-butylethanolamine and methylethanolamine. Other amine-containing monomers are vinyl pyridine and similar amines with a polymerizable double bond.

One or more of the above-mentioned amine-containing unsaturated compounds are mixed with monomers which do not carry an electrical charge and do not have an active hydrogen atom, so they do after polymerization can be described as non-functional. Typical non-functional monomers of this type are unsaturated hydrocarbons, such as isoprene, butadiene, ethylene, Styrene and vinyl acetate, and unsaturated halogen compounds such as vinyl chloride and vinylidene chloride. if it is desirable to multiply the number of crosslinking sites over the number of resulting from the amine compounds To increase the corresponding sites, unsaturated, active hydrogen-containing compounds can then be added such as monoesters of diols with unsaturated acids such as hydroxylpropyl methacrylate. For the purposes of the present invention is an active hydrogen atom defined as such, which to a reaction with

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is capable of the formaldehyde condensates specified in this description. Polymerization of these unsaturated monomers is carried out in the presence of a free radical source such as a peroxide, a solvent and optionally a chain transfer agent. The amine-containing polymer obtained is one of the components of the electrophoretic coating composition according to the invention.

Specific examples of formulations which produce amine-containing organic polymers in the presence of free radical sources are listed below:

Table I. Typical amine-containing organic compositions.

lot

(Wt .- #, based on the dry weight of the poly monomer mera)

1. iithylacrylate 35

2. methyl methacrylate 4-0

3. t-butylaminoethyl methacrylate 23

total 100 %

1. Dibutyl maleic ester 35

2. methyl methacrylate 4-0

3. Styrene 10 4 ·. t-butylaminoethyl methacrylate 15

total 100 #

1. Ethyl acrylate 30

2. methyl methacrylate 4-0

3. Styrene 10 4-. Hydroxylpropyl methacrylate 10 5. Dimethylaminoethyl methacrylate 10

total 100 %

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23450U

Monomers Vinyl acetate all in all lot
(Wt .- ^, based
on dry Ge
weight of the poly
mers) Table I (continued) 1. Bibutyl maleate 21.8 2. t-butylaminoethyl methacrylate 26.7 3. Butyl peroctoate 10.9 4-. Dodecyl mercaptan ■ 0.3 ' 5. toluene 0.3 6th Butanol 16.3 7th 23.7 100.0 %

According to the invention, the amine-containing organic coating material can be prepared by using between 2 and 50 #, based on the total moles of Monomers, a polymerizable amine-containing unsaturated Compound, 0 to 50 mol # of a vinyl polymerizable, unsaturated hydroxy compound and otherwise at least one non-ionic unsaturated compound, which is copolymerizable with the other monomer or monomers is combined.

Amine-containing polymers of the condensation type can also used as a polymer component in the electrophoretic coating compositions according to the invention will. A polyester (a polyamide or polyurea or polyurethane), the 8n the chain ends with amine groups can be completed by a polycondensation reaction getting produced. In a process for the production of such condensation products η-column of a difunctional carboxylic acid (e.g. Phthalic acid, oxalic acid, adipic acid or sebacic acid) with at least n + 1 KoI of a clifunctional, active

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Hydrogen-containing compound which has at least one amino radical, condensed. Typical active Compounds containing hydrogen are diamines, alkanolamines and mixtures of dihydroxyl compounds with diamines or alkanolamines Such condensates can dur'ati the following general formula can be represented:

Y _x 0 0 0 / X

\ I Ii IU /

N-C / Q-C-Z-C / Q-C-N X ^ Y

wherein X and Y represents a Wasserstoffstom or a C ^ - C ₆ are -.Alkylradikel; Q stands for a group of the formula "" (CHg ^ m "(where m is an integer from 1 to 9) and Z stands for - (NH ₅ ) -R ₆ -KRf-, -O-Rg-0- or - 0-R ₆ -NR ₅ -. (Where R _{r is} hydrogen or a C 1 _{-C 6} -alkyl group and Rg is - (CHp) - or a phenyl group, where s is 2 to 9).

Condensation products containing amino radicals can; can also be obtained by using tricarboxylic acids and multifunctional "active hydrogen containing compounds" is used wherein all or part of the active hydrogen atoms are on an amine group. All or some of the chain ends of these products can represent amino radicals. The condensation of the components can be obtained by the multifunctional acids or their methyl or ethyl esters with the multifunctional active hydrogen-containing compounds heated or that one multifunctional acid chlorides or chloroformates of diols in organic Solvents with aqueous solutions of the multifunctional len active hydrogen-containing compounds converts. Other amine-capped polycondensation products can

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can be made in a similar manner.

An example of an approach / which is an amine-terminated one Condensation polymer results is one that contains 4-1.8 parts of dimethyl terephthalate, 18.7 parts of trimethylolpropsn, 12.8 parts of methylethanolamine, 0.7 parts of tin (IV) octoate and 26.0 parts of diisobutyl ketone, all parts being parts by weight.

B. The formaldehyde addition products .

The deposited on electrophoretically coverings, which are obtained by the use of the inventive polymer compositions can be crosslinked or cured at elevated temperatures, wherein reactive condensation products of formaldehyde with phenol or with other appropriately substituted aromatic hydrocarbons used $ if ^v where $ e ± latter with formaldehyde react so that two or more methylol groups (-GHqOH) are attached to an aromatic hydrocarbon ring. Preferred co-reactants for the formaldehyde are 1) phenol, 2) alkyl or alkylene ethers of phenol and 3) aromatic hydrocarbons with at least two alkyl substituents on a benzene ring structure, such as xylene.

For the production of coverings that require greater flexibility It may be desirable to show the formaldehyde condensation product mentioned above beforehand with a diglycidyl ether of an aromatic or aliphatic dihydroxyl compound to implement. The stoichiometry of the reaction should be such that an average of at least two Methylol groups per molecule of reaction product are retained. This can easily be achieved by adjusts the Heakbionsbedingungen accordingly and the amount of water formed as a by-product of the reaction measures. Products of this type and their manufacture are in

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- ίο -

in US Pat. No. 2,825,712, the information in this Patent specifications are intended to be included in the present application.

The various types of phenol / aldehyde condensation products and their preparation are well known and do not need to be described in detail. An excellent overview of the same can be found in volume 10 of "Encyclopedia of Polymer Science and Technology" edited by FI. Mark and N. Gaylord (Interscience Publishers, 1969).

The weight ratio of the formaldehyde condensation product to the amine-containing polymer is between 1: 9 and 9 * 1

C. Additional components of the coating composition.

In addition to the neutralized amine-containing polymer, the formaldehyde condensation product and water, the coating compositions can contain one or more additional components, such as pigments, stabilizers, fillers and catalysts, in order to promote the curing of the finished covering carried out at an elevated temperature, one or more organic solvents, preferably alcohols or ketones which have relatively high boiling points and thus have low volatility, such as methyl heptyl ketone, can be present to aid in the dissolution of the amine-containing polymer or the formaldehyde condensation product, whereby a more homogeneous film is obtained.

D. Preparation of the coating composition «

The aqueous coating compositions of the "invention are preferably prepared by mixing a solution of the amine-containing polymer with the formaldehyde

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condensation product mixes and nan at least partially the obtained composition with an organic acid neutralized, which forms an anion that is soluble or dispersible in an aqueous medium. Suitable Acids contain between 1 and 10 carbon atoms. Then gradually water becomes with sufficient stirring added so that a homogeneous aqueous emulsion or dispersion is obtained which shows a solids content, i.e. a concentration of non-volatile materials, cer between 3 and 25 wt .- $, preferably between 8 and 15 wt. JiS.

Any pigments, fillers ■ or other additional solid constituents are expediently made by dispersing them in at least a portion of the main non-volatile components incorporated to make a concentrate, which is then incorporated with the rest of the emin-containing resin and formaldehyde condensation product is combined. That resulting mixture is then neutralized and emulsified as described above. When using pigments then these can be between 0.5 and 50 wt .- #, based on the non-volatile materials in the composition, turn off.

Another method for producing the oil-in-water emulsion is carried out by slowly adding the organic! "Hase (oil phase) to strongly" stirred (for example by strongly shear mixing) water which contains the required amount of neutralizing acid. The particle size of the emulsion obtained can be further reduced, if necessary, by homogenization using a suitable colloid mill.

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E. Application and curing of the pavement compositions .

In the electrophoretic deposition process, at the above-mentioned aqueous coating compositions are used, the aqueous composition is provided with an electrically conductive anode and an electrically conductive cathode in contact, the surface to be coated being the cathode. When passing electrical current between the anode and the cathode while they are in contact with the the coating composition containing bath in Are in contact, an adhesive film of the pavement composition becomes deposited on the cathode. This is in contrast to processes in which neutralized poly-carbonic acid resins can be used, which are deposited on the anode. Many of the benefits described above are there attributable to this cathodic deposition.

The conditions under which the electrophoretic deposition are generally the same as those used in electrodeposition other types of covering can be used. The applied voltage can be varied widely, and it can vary from 1 volt to several thousand volts, although it is typically between 50 volts and 5 ^ 0 volts. the Current density is typically between about 0.09

ρ
and 1.55 A / m and shows a tendency to decrease phoretic separation,

ρ
and 1.55 A / m and shows a tendency, while the electrical

The method according to the invention is applied to the coating all electrically conductive substrates can be used, in particular for the coating of metals, e.g. Steel, aluminum, copper and the like and metal coated substrates.

After the deposition, the Beia <r is at increased temperature

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doors hardened by any convenient process, such as baking in ovens or infrared heating lamps. Preferably Kärtungstemperatüren be used from 150 to 22O ⁰ C, although Härtungstemperatüren may be desired from about 120 to about 260 ⁰ C or more.

The following examples demonstrate preferred embodiments the invention. They should not be taken as limiting. All parts and percentages are expressed by weight unless otherwise specified.

This example demonstrates an amine-containing acrylic polymer and a glycidyl ether modified condensation product of formaldehyde and a phenol derivative.

^A · Production of the amine-containing polymer .

A reaction vessel equipped with a mechanical stirrer, a reflux condenser, a thermometer, a nitrogen inlet and an addition funnel was charged with 30 parts of methyl ethyl ketone. The contents of the container were ^{heated to reflux temperature (approximately 80 0} G), whereupon 70 parts of a Geraischa made of 33 % methyl methacrylate, 25 # t-butylaminoethyl methacrylate and 4-2 % n-butyl acrylate together with 0.28 parts of a polymerization initiator (Azo-bisisobutyronitrile) were added. The mixture was held between 80 and 90 ° C. during the addition and then for a further 2 hours. Then 0.28 part of an initiator was added. A third portion of 0.035 parts of initiator was added after a further hour of heating at 80 to 90 ⁰ O. The mixture was heated for an additional hour following the final addition.

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B. Preparation of the formaldehyde condensation product .

The formaldehyde condensation product was prepared by producing a melt from a mixture containing 75 parts of a diglycidyl ether of Bi ¹ S-phenol-A, which had a melting point between 65 and 75 0, an epoxide equivalent weight of 425 to 550 and a hydroxide equivalent weight of 0 , Possessed 28 equivalents per 100 g of resin and contained 25 parts of a condensation product derived from allyl phenyl ether and formaldehyde. The product contained between 1 and 3 methylol groups per molecule. The reaction was catalyzed by the use of 0.1 % triethylamine (based on total reactants). The mixture was combined with 9 parts of toluene and heated for 2 hours at a temperature of 100 ⁰ C, whereupon it is cooled with a mixture 8US the monomethyl ether of ethylene glycol (70%) and 2-ethylhexanol (30 #) diluted wur'de to to achieve a solids content of 80 %.

C. Preparation of the electrophoretic coating kit.

A mixture of the acrylic polymer solution (57 parts) and the formaldehyde condensate (75 parts) was reacted with sufficient formic acid to neutralize any amine groups present in the polymer. Then gradually became water with stirring:. added to prepare an emulsion in which the solids content is 10 wt - was.%. The emulsion was placed in a tank equipped with an anode and a cathode connected to a DC power source. A voltage of 200 volts was applied to the two electrodes for 60 seconds, during which a coating was deposited on a steel plate connected as a cathode, which was coated with zinc phosphate and was 10-15 cm in size

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exhibited. The plate was then removed from the bath and generally rinsed with cold water, after which the excess water was removed using a stream of compressed air. The plate was then introduced 15 Hinuten in an oven at a temperature of 204- ⁰ G. The hardened coating was smooth and shiny. The covering showed no loss of adhesion to the substrate and no visible cracks when exposed to an impact of 1.5 mkg. The test was carried out using a Gardner Wedge Impact Tester.

A pigmented composition was prepared using the above-mentioned acrylic polymer and formaldehyde condensation product. 60 parts by weight of a mixture containing 94, 3% by weight of titanium dioxide and 5.7% by weight of carbon black became homogeneous with 40 parts of the Formaldehyde condensation product and 14 parts of 2-ethylhexanol mixed. 33 parts of the paste obtained were combined with 18 parts of an acrylic polymer solution which had been prepared according to Part A and 213 parts of the above-mentioned formaldehyde condensation product. The mixture obtained, which is 5 _? Containing 3 wt .- ^ pigment, was completely neutralized using 0.13 parts of formic acid and then combined with 274-8 parts v / water. The emulsion was applied by electrophoretic method to steel plates coated with a zinc phosphate coating, as described in the previous paragraph. The coated panels were then heated for 0.5 hours at a temperature of 204- ⁰ C to cure for the coating. The film obtained was glossy and withstood an impact of 1.3 mkg without cracking.

Example 2

A & 9.4- # (weight) solution of an acrylic polymer in Diethyl ethyl ketone was prepared with the following

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Monomer composition was used:

4-5 % ethyl acrylate

10 % methyl methacrylate

10 % hydroxylpropyl methacrylate (purity 90 #) Λ0% styrene

25 % t-butyl-aminoethyl methacrylate.

The initiator used was azo-bis-isobutyronitrile.

A homogeneous mixture was prepared using 252 parts of the above-mentioned polymer solution and 166.0 parts of a product prepared by reacting a solid bisphenol-epichlorohydrin type epoxy resin with a xylene-formaldehyde condensation product. as described in U.S. Patent 2,825,712 and available as "Kethylon® Resin No. 75202" from General Electric Company ("Kethylon® ¹ is a registered trademark). An amount of formic acid was then added sufficient to cover all of it Amine groups to neutralize acrylic polymer, followed by the gradual addition of water with sufficient agitation so that a stable emulsion was obtained containing between 5 and 25 % of the non-volatile materials. The resulting composition was electrophoresed to zinc phosphate The coated steel plate was cracked open using a voltage of 100 V. The application was carried out for 60 seconds, and after a water rinse, the coated plate was cured by placing it in an oven at a temperature of 190 ⁰ O for 20 minutes. The adhesion of the covering was not significantly affected by immersion in hot aqueous alkali for 14-4 hours influences.

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Example 3

An acrylic polymer was made as a 59.5% solution in monomethyl ether made of ethylene glycol using the following monomer composition:

60 % methyl methacrylate

15 # t-butylaminoethyl methacrylate 25 # butyl acrylate.

A homogeneous mixture was prepared using 579 parts of the above polymer solution and 127 parts of a partially polymerizing and essentially uncrosslinked mixture of the allyl ethers of mono-, di- and trimethylol phenol known as "MethyloiP Resin No. 75121"("Methylon® ¹ is a registered trademark) from General Electric Company An amount of aqueous formic acid sufficient to neutralize 70% of the theoretical amine content of the acrylic polymer was added, followed by the addition of sufficient water to produce a prepare emulsion containing 10 wt -..% contained non-volatile materials a coated with zinc phosphate steel plate which was used as a cathode in an electrophoretic bath, was "·, coated using a voltage of I50 volts for 60 seconds. The covering was cured at a temperature of 121 ^° C. for 20 minutes. The hardened covering was glossy and adhered well to the plate.

Example 4-

A homogeneous composition was prepared using 90 parts of a polyamide resin that was derived from dimeric Linoleic acid and diethylenetriamine (amine value »210 to 220) and 375 g of "Methylone Resin No. 75121" as in Example 3 was used. The amine value is equal to the number of milligrams of potassium hydroxide that 1 g of polyamide

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234504A

resin, as determined by titration with aqueous hydrochloric acid. The above mixture was combined with an amount of acetic acid sufficient to neutralize 17.5 # of the amine groups on the polyamide. The resulting composition was then combined with sufficient water to give an emulsion containing 10% by weight of non-volatile materials.

A zinc phosphate coated steel plate was electrophoretically coated as described in the previous examples, applying a voltage of 50 volts for JO seconds. The covering, which had been obtained following heating to 204 ^° C. for 15 minutes , was glossy and showed good adhesion to the substrate.

Claims;

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Claims (6)

PATENT CLAIMS: 1. Crosslinkable aqueous polymer composition which is suitable for cathodic electrophoretic coating, characterized in that the film-forming
Components of the composition are the following: a) an 8minhaltiges polymer, wherein at least some of the amino radicals in the form of the ammonium salt of a
Carboxylic acid are present, the repeating units which contain the amino radicals being between 2 and 50 #, based on the total number of moles of the repeating units in the polymer; and b) a heat-reactive condensation product of formaldehyde with a phenol or a suitably substituted aromatic hydrocarbon, the condensation product on average at least two
Has kethylol radicals (-CH ₂ OH) per molecule5 wherein the weight ratio of component (a) to component (b) is between 1: 9 and <~): Λ and wherein the
Combination of components (a) and (b) between 2 and
25 wt .- / 6 of the aqueous polymer composition makes up. 2. Composition according to claim 1, 'characterized in that the amine-containing repeat units
of the amine-containing polymer are derived from an aminoalkyl acrylate or methacrylate. 3. Composition according to claim 1, characterized in that the condensation product is a reaction product of formaldehyde and a compound consisting of
Phenol, alkyl ethers of phenol and the three possible
Xylene isomers is selected. 4-, composition according to claim 3, characterized 409811/1180 23450U draws that the reaction product is then added a Mfflycidyläther implemented a polyhydric alcohol has been. 5. A composition according to claim 1, characterized in that up to 50 wt. ~% Contains one or more pigments. 6. Use of the composition according to any one of claims 1 to 5 for electrophoretic deposition of deposits on a cathode. PATENTAItWlTB OR .IHC, H ΓΙ -. '. Ι-ί D Il-l'i' ^ 09811/118