DE1267363B - Binder for aqueous coating compounds for the electrophoretic application process - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. CL:

German class:

Number:

File number:

Registration date:

C09d

B44d
C08g

22 g -10/01

75c- 5 (01

39 c-16

June 8, 1964

Open date: May 2, 1968

The invention relates to the use of water-thinnable synthetic resins as the sole binder in unpigmented, pigmented or otherwise provided with suitable fillers coating compounds, which are suitable by the electrophoretic method of application (electro-coat process) to metallic or other bodies which conduct or have made conductive the electrical current to be applied.

The synthetic resins used according to the invention consist of a complete or free carboxyl groups partially neutralized with ammonia or strong organic nitrogen bases containing resin, which is composed of a monohydric and polyhydric alcohols or polyhydric alcohols only partially esterified adduct α, ^ - ethylenic unsaturated dicarboxylic acids or, if the latter are able to form anhydrides, their anhydrides to drying and / or semi-drying oils and / or their fatty acids and / or esters thereof with polyhydric alcohols and / or resin acids (rosin) and / or partially hydrogenated resin acids and / or esters of resin acids with polyhydric alcohols.

It has been found that process Electro-coat applied to these resins produced solutions or dispersions, according to the result in coatings which provide excellent after baking at 150 to 18O ⁰ C corrosion protection. The waiver of the usually customary admixtures of hardening substances, such as. B. aminoplasts or phenol resols, etc., or the waiver of reactions with hardness-increasing compounds, such as. B. the copolymerization with vinyl compounds, has the great advantage of having a resin that is relatively uniform in molecular size.

U.S. Patent 2,414,712 at column 5 at lines 58 to 66 discloses that one the adducts of maleic acid to dehydrated castor oil with polyalcohols can esterify to oil-soluble synthetic resins of the alkyd type and those for the preparation of film-forming mixtures are suitable. These recommendations apply to oil-soluble alkyd resins and not to water-soluble ones Resin types.

Furthermore it will a. a. O. in column 6 in lines 5 up to 13, especially line 9, indicated as necessary for the preparation of aqueous lacquer solutions, that the adducts described there are to be reacted with a lower monoalcohol to form the half ester and to neutralize this.

In British patent specification 925 038 a water-soluble resinous agent is described which by

Binder for aqueous coating compounds
for the electrophoretic application process

Applicant:

Reichhold Chemie Aktiengesellschaft,
2000 Hamburg-Wandsbek

Named as inventor:

Dr. Rolf Güldenpfennig, 6901 Dossenheim

Air drying changes into water-soluble form and that is a water-soluble salt of the reaction product

ao from a drying oil, maleic anhydride, acrylic and / or methacrylic acid and in particular an ethylenically unsaturated monomer which is free from acidic carboxyl and carboxyl anhydride groups is presented, layed out. However, this known coating agent does not contain such adducts that are im Following the adduct formation with monohydric and polyhydric or polyhydric alcohols alone are partially esterified.

Furthermore, it is indicated on page 1 in lines 31 to 41 that various male oil adducts through Treating an oil with maleic anhydride have become known. These well-known adducts have high acid numbers and can be esterified with polyols or neutralized with bases. Water soluble Products can be obtained from these adducts if there is enough maleic anhydride in the oil has inflicted. However, the water-soluble products obtained are and are very slow drying on the other hand, unsatisfactory for the production of coating compositions.

In British Patent 500,349 there is a process for preparing an aqueous coating composition described by a mixture consisting of a carboxylic acid or an acid derivative which contains a «, ^ - unsaturated group, or a carboxylic acid, which receives such a group when heated, as well as an oil or oils which are known as triglyceride esters unsaturated fatty acid with at least 12 carbon atoms, the oil having less than 10% compounds with conjugated Double bonds, or with such acids, obtained by hydrolysis of such oils are reacted with a water-soluble base. Here

809 574/442

3 4

only neutralized adducts are obtained, the inconsistent yellowing of the film on baking, good

have subsequently been esterified with alcohols. Elasticity of the burned-in films and high corrosion

In the German Auslegeschrift 1 036 426, the penetration resistance of the stoved films is characterized Burning varnishes described, consisting of neutralization This fact ensures uniformity products of acidic esters, which by reaction of the deposited coating over a large period of time of di- or polybasic carboxylic acids or space and facilitates refilling of the electrode Mix with less than the equivalent phoresebades with the resin to the required Amount of monohydric and / or polyhydric alcohols, solids content. Manufactured at the previously known Elektro are, with amines or amine mixtures, phoresis baths that contain synthetic resins, prepares the the neutralization products possibly having considerable difficulty in regeneration. The left During their formation with thinners, various coatings are primarily used for corrosion purposes Water, to be diluted. sion protection, but can also be used for sound and

In this interpretation, as polybasic car vibration damping are meaningful,

bonsäuren no adducts α, / 9-unsaturated dicarboxylic It is to be regarded as surprising that the according to acids and are also referred to by this document as synthetic resins used in the invention, although these

not suggested. Contain ester groups, in the alkaline electrical

Electrophoresis, as an economical and phoretic bath, has good storage stability,

Quality-improving application process for paint - The α, / 9-ethylenically unsaturated dicarboxylic acids

substances known (cf. "Color and Varnish" 1964, p. 271 bis or their anhydrides, such as maleic acid, 279, as well as "Paint Technology", December 1963, p. 13 20 fumaric acid, itaconic acid, citraconic acid, mesaconic acid

to 23). In "Farbe und Lack", 1964, p. 272, left acid, aconitic acid, are at about 180 to 220 ° C

Column, lines 29 to 33, states that the liquid with oils and / or resins and / or fatty acids and /

system of extremely complex structure or fatty acid and / or resin acid esters polyvalent

is and consequently also the ger alcohols taking place in it in a known manner so for the reaction

Processes when an electrical DC voltage is applied, that the molar ratio of dicarboxylic acids

tion. The exact knowledge of these factors is natural to fatty or resin acid is about 1: 0.5 to 1: 2;

borrowed one of the most essential requirements for the preferred is a ratio between 1: 1 and

Production of paints, which is 1: 1.5 for this ratio.

are suitable (op. cit., page 278, left) The adducts are then used with mono- and polyvalent

Column, lines 18 to 21). These works are still in the alcohol or polyhydric alcohols alone

Stage of development, so that still implemented in practice. The amount of alcohol is calculated in such a way that

there are great difficulties, but on the other hand still that the ratio of carboxyl groups to hydroxyl

it is possible to produce single-layer lacquer groups (one anhydride group should be used as two carboxyl groups

with properties that have not yet been found (e.g. groups are assessed) in the initial mixture

Cit., Page 279, left column, lines 16 to 20). 35 ranges from 1: 0.7 to 1: 1.9, with

In the magazine "Paint Technology" is where the most favorable results with a ratio between two-paragraph with the heading "Basic Principles" can be seen 1: 0.9 and 1: 1.6, give that physical and chemical reac- As polyhydric alcohols as they are at various Functions are extremely complicated and many more basic passages of this invention are mentioned, the enclosed ones apply Work is required to make it, for example, ethylene glycol, di-, tri- or polyethylene, glycol, 1,2-propylene glycol, 1,3-propylene glycol, di-,

In the Belgian patent 633 074 is in the case of tri- or polypropylene glycol, 1,2-, 1,3-, 1,4-, 2,3-bus game 6 and in claim 5 a water-thinnable, ethylene glycol, neopentyl glycol, trimethylolpropane, pen for electrophoresis suitable sole binder taerythritol, glycerine, etc., whereby trimethylolpropane, described, which is an addition product of a 45 glycerol, pentaerythritol and ethylene glycol the preference Ethylenic dicarboxylic acid and / or its Anhy- is given.

drids, for example maleic acid to esters, which are not monohydric usable alcohols for example

Contain saturated fatty acids and which, for example, methanol, ethanol, the various propanols, n-,

are linseed oil or wood oil. These binders, iso-butanol, amyl, hexyl, heptyl, octyl,

medium have the major disadvantage that these 50 nonyl, decyl alcohol and higher alcohols to which

electrophoretic application no smooth film - also the fatty alcohols count.

deliver surfaces. It also turned out to be favorable to the reaction between

extremely strong adducts and alcohols that are so permeable when stoving.

kem measure. These stoved films are brittle and all anhydride groups are opened

and have insufficient corrosion resistance. 55 and the more acidic carboxyl group is esterified.

In addition, these known resins do not give the more acidic carboxyl group when esterified

Electrophoresis only insufficient coverage, and complete - this can be the case, if only

the current yield is relatively low. polyhydric alcohols are used - it is

The object of the present invention is favorable to the anhydride which cannot be opened with alcohol

such water-thinnable synthetic resins completely add 60 groups before reacting with the alcohols

or partially hydrolyze with ammonia or strong organic. Are more than half of the

Nitrogen bases neutralized when the electrophoretic oxyl groups are esterified, this is the limit of implementation

see application as sole binder to be used due to two criteria:

those who have the disadvantages of the previously mentioned "^. . . . ,,,. ,

Do not own the proposed resins and get through 6 ₅ * ·? «with ammonia or strong organic

smooth surfaces of the soap produced electrophoretically with good nitrogen bases must be water-

Layer thicknesses, high current yield while being dilutable at the same time;

high coverage of the deposited film, low 2. due to the gelation limit.

The resins achieve solubility in water by neutralization with ammonia or strong organic compounds Nitrogen bases, such as triethylamine, diethylamine, trimethylamine, triethanolamine, diethanolamine, Piperidine, morpholine, etc. The soap formation should be increased at room temperature or only slightly Temperatures take place in order to avoid saponification of the ester. To achieve sufficient water thinnability it is not always necessary to have the theoretically necessary for complete neutralization Amount of base to apply; often the required water dilutability is achieved even with a smaller amount achieved.

Under water-dilutable those partially or completely neutralized resins are understood that alone or at least with the addition of a minor amount of an unlimited or largely in water soluble solvent are soluble or dispersible in water.

The water-thinnable resins obtained in this way are converted into ready-to-use electrophoresis baths by adding water, optionally pigments and / or other suitable fillers. When a DC voltage is applied to the conductive body to be coated, which is immersed in the bath as an anode, a firmly adhering film is deposited on this body from the baths. If the deposited film does not have air-drying properties, it is stoved.

For example, to produce an immersion liquid suitable for the electro-coat process, which is used to deposit corrosion-resistant coatings (primers), the water-thinnable resin is mixed in 50% concentration with iron oxide red in the binder pigment. Ratio 1: 0.5 rubs on a ball mill for 2 to 3 days and the dispersion obtained is diluted with pure water to a solids content of 10 to 20%. In this form, it is filled into the electrophoresis basin, in which the metallic objects to be painted are placed as an anode. After applying a DC voltage of about 100 volts, a dense film separates which after about 30 minutes of baking at 150 to 180 ⁰ C a hard, elastic, adherent and representing corrosion protective coating. (You can also work with higher or lower voltages.)

example 1
(T is understood to mean parts by weight)

I. Manufacture

of the water-thinnable synthetic resin
27.5 T ricin oil, 1ot soybean oil, rosin 5 T and 0.7 T of pentaerythritol are esterified at 270 ° C to an acid number of about 3 and then 10 T maleic anhydride reacted in a known manner at 180 to 220 ⁰ C. The adduct is reacted successively with 2 parts of butanol and 10 parts of trimethylolpropane until an acid number of about 90 is reached. The reaction product is adjusted to a solids content of 50% and a pH of 7.8 to 8.2 at a maximum of 40 ° C. with pure water and ammonia solution.

II a) Use of the resin for production

an unpigmented coating mass
10 kg of the 50% resin are diluted with 40 kg of pure water.

Hb) Use of the resin for production
a pigmented coating compound (primer)

10 kg of the 50% resin become red with 2.5 kg of iron oxide rubbed in a ball mill for 3 days and the dispersions obtained with pure water diluted to a solids content of about 12%.

III. Electrophoretic deposition of the coating

The coating compositions Ha) or Hb) are filled into the electrophoresis tub in which the to be coated immersed metallic object as anode. On the latter, the mass separates after being applied a direct voltage of about 100 volts as a dense, uniform film. 30 minutes at 150 ° C Burned in, it gives a coating that is very resistant to corrosion.

Example 2
I. Production of the water-thinnable synthetic resin

27.5 T dehydrated castor oil, soya oil 1ot, 5 T rosin and 0.7 T of pentaerythritol are esterified at 26O ⁰ C under an inert gas up to an acid number of approximately zero. To facilitate the esterification, an azeotropic agent removing the water of reaction, e.g. B. xylene or vacuum, operate. After the entrainer has been removed, the reaction is carried out in a known manner with 10 P maleic anhydride at 180 to 220 ° C. When the adduct has been formed, the reaction is carried out with 2 T butanol in such a way that the batch is kept at 100 ° to 105 ° C. for about 2 hours. Are then added 1ot trimethylolpropane and maintains a temperature of 90 to 100 ⁰ C until it reaches an acid number of about 90th With pure water and aqueous ammonia solution or triethylamine or dimethylethanolamine the resin at maximum 4O ⁰ C to a solids content of 60% ^an d a pH value of 7.0 to 8 (measured in 20% strength aqueous solution). The stability of the aqueous resin solutions increases from ammonia via triethylamine to dimethylethanolamine.

Ha) corresponds to example 1, paragraph Ha).

Hb) Use of the resin for production
a pigmented coating mass

(Primer and one-coat paint)

10 kg of the 60% igeti resin according to Example 2 are used rubbed with 3 kg of iron oxide red in a ball mill and the dispersion obtained with pure Water diluted to a solids content of about 12%. To reduce the viscosity you can when grinding 10 to 15% of a glycol ether, e.g. B. ethyl glycol, are added. The percentage refers to solid resin.

III. The electrophoretic deposition corresponds analogously to Example 1, Section III.

Example 3
Production of the water-thinnable synthetic resin

27.5 T dehydrated castor oil, 1 T soybean oil, 5 T rosin and 0.7 T pentaerythritol are used, as in Example 2, Section I, described, esterified and with 11.8 T of fumaric acid in a known manner

180 to 22O ⁰ C implemented. The adduct formation is 0.5 T of water a part of the adducts digested,

finished when the resin stays clear in the cold. The batch is kept at 100 ^° C. for about 2 hours.

Then 10 parts of trimethylolpropane are added and 10 parts of trimethylolpropane are then added

esterified at about 150 ⁰ C until an acid number of added and the temperature is from 90 to 100 ° C about 100 is reached. The neutralization, the 5 about 2 hours. Dilution, neutralization and

dimming and the use correspond to the use correspond to examples 1 and 2. Examples 1 and 2.

Example4 example

I, Production of the water-thinnable synthetic resin "Production of the water-thinnable synthetic resin

27.5 T dehydrated castor oil, 10 T soybean oil, 5 T Ko- 27.5 T dehydrated castor oil, 10 T soybean oil, lophonium and 0.7 T pentaerythritol are at 260 to 5 T rosin and 0.7 T pentaerythritol are to 270 ° C esterified to an acid number close to zero. according to Example 1 up to an acid number. B. xylene, anhydride implemented in a known manner. The adduct or vacuum can also be used. After completion, the esterification and removal of the entrainer are reacted at 100 to 105 ° C. with 2 T butanol for about 2 hours. Then, 6.9 t of glycerol are added to 220 ⁰ C and cooked at about 140 to 145 ⁰ C, is reacted in a known manner until the zuwird 10 T maleic anhydride at 180th After finishing the ao resin is also cold bare. An acid number of adduct formation is cooled to about 100 ° C, reached with about 135. The neutralization and the Ver 0.5-T added water, and about 2 hours at 100 to dilution as well as correspond to the use of 105 ⁰ C. Subsequently, 1OT tri- examples 1 and 2. niethylolpropane are added and the batch is held again

about 2 hours until an acid number of about 90 is obtained

is enough. The neutralization can be carried out with aqueous _TT ", ·, ..-, ^ ^

Ammonia solution, triethylamine or dimethyl production of the water-thinnable synthetic resin

Ethanolamine take place as in Examples 1 and 2 In Examples 1 to 8 is described instead of became. hydrated castor oil the same amount of isomeric

Ha), Hb) and III correspond to Example 1 used safflower oil. The products received according to. can be used in the same way.

Example 5

TT λλ λ j »ι t ^ ι Examples 17 to 24

Production of the water-thinnable synthetic resin

27.5 T dehydrated castor oil, 1 T soybean oil, 35 Manufacture of the water-thinnable synthetic resin 5 T rosin and 0.7 T pentaerythritol are, In Examples 1 to 8, instead of de-

as described in Example 2, paragraph I, esterified hydrated castor oil safflower oil is used. The and reacted with 1OT maleic anhydride. The viscosity of the neutralized resins is concentrated adduct T water is digested at 100 ⁰ C at 1. trated aqueous solution lower than in the case of the end of the holding time of about 2 hours at 40 play 1 to 16. 8 T trimethylolpropane Example 25

added and the temperature from 90 to 100 ⁰ C

held until an acid number of about 140 is reached. The procedure is as in Example 1, but on

Neutralization, dilution and use of 2 T butanol 0.8 T methanol used, speak of Examples 1 and 2. 45 The acid number is set to a value of about 80 to 85

brought. Following the esterification, the

Example 6 approach for about 2 hours with 2 parts of water at 100 ⁰ C

_TT ", j ·· 1. rr 1 held. The result is resins which, with respect to the

Production of the water-thinnable synthetic resin film resistance have a higher storage stability.

27.5 T dehydrated castor oil, 1OT soybean oil, 50

5 T rosin and 0.7 T pentaerythritol are used at B e i s ρ i e 1 26

260 to 270 ⁰ C, as described in Example 2, esterified and reacted with 10 P maleic anhydride. 42.5 T dehydrated castor oil, safflower oil 40 T, The adduct is treated with 13.6 T trimethylolpropane 30T soybean oil, gum rosin and 15 T 2 T and esterified at 15O ⁰ C, until the acid number 55 of pentaerythritol are the addition of xylene to approximately 70 has fallen. The esterification is purposefully esterified at 260 to 270 ^° C. until the acid number is moderately carried out under vacuum. Dilution, new has dropped to almost zero. The xylene is then distilled off; neutralization and use correspond to the examples with 38 parts of maleic anhydride play 1 and 2 reacted at 180 to 220 ⁰ C, is dropped to the content of free maleic anhydride ^6o Example 7 below 1%. The _TT . _1t , j .. 1 T ^, presence of 0.15 T triphenyl phosphite during preparation of the water-thinnable synthetic resin the adduct formation can have beneficial effects on the color

27.5 T of dehydrated castor oil and 10 T of soybean oil of the adduct have an effect. Then with

^{are heated to 25O 0} C for 1 hour, reacting for 4.6 T of ethanol for 2 hours at 100 ⁰ C and with

ensures the exclusion of oxygen. Then 65 37.2 T trimethylolpropane at one temperature

it is esterified with 10 P maleic anhydride at 180 to below 150 ^° C. until the acid number is 70 to 75

220 ⁰ C in a known manner. After finished amounts. Neutralization, dilution and use

Adduct formation is ^{cooled to 100 °} C. and corresponds accordingly to Examples 1 and 2.

Example 27

165 T safflower oil, soybean oil 60T, 30T rosin and 3.9 T of pentaerythritol are esterified in a known manner at 260 to 27O ⁰ C until an acid number of approximately zero. Thereafter, it is reacted at 180 to 220 ⁰ C and 92 T, maleic anhydride is dropped to the content of free maleic anhydride I ⁰ I _0th The adduct is partially digested with 11.4 parts of ethanol at 80 to 100 ^° C. for 2 hours and then boiled with 93 parts of trimethylolpropane at a maximum of 150 ^° C. until the viscosity of the product (50% measured in butyl glycol) has a value of G ( Gardner). Following the esterification, the mixture is held at 100 ° C. for a further 2 hours using 5 parts of water. Dilution, neutralization and use correspond analogously to Examples 1 and 2.

Comparison s example

The behavior of two resins was compared with one another:

1. the resin according to Example 2 of the present invention,

2. the resin according to example 6 of Belgian patent 633 074.

In order to get comparable results, both resins were neutralized with triethylamine and diluted with water to a solids content of 10%. This solution was poured into an electrophoresis test tank which has a capacity of 2 liters. The cathode-anode distance was 16 cm. The area of the cathode and the anode was 150 cm ² each. The resins were electrophoretically deposited from the aqueous solution by applying a voltage of 101 volts in 120 seconds. The metal sheets were then rinsed with water and baked in a drying cabinet at 170 ° C. for 30 minutes.

1. Resin according to Example 2 of the invention:

Layer thickness 31.25 μ

Specific film resistance .. 2320 · 10 ⁴ Ω · αη
König pendulum hardness 112 seconds

2. Comparative resin according to Example 6 of Belgian patent 633 074:

Layer thickness 37.5 μ

Specific film resistance .. 1613 · 10 ⁴ Ω · αη
König pendulum hardness 34 seconds

By visual comparison of the two coated sheets, it can easily be determined that the comparative resin according to the prior art is an essential one has a stronger yellowing and, compared to the resin according to the invention, a much more restless one Has area. The superiority of the product used according to the invention over that by the Belgian patent 663 074 is clearly proven. That according to the invention The product used is much harder with a comparable layer thickness and also has a higher film resistance and, associated with it, a higher throwing power, which is

ao phoretic coating has a particularly beneficial effect.

Claims (1)

Claim: Use of water-thinnable synthetic resins made entirely or partially with ammonia or strong organic nitrogen bases neutralized with monovalent and polyvalent or polyvalent ones Alcohols only partially esterified adducts «, ethylenically unsaturated dicarboxylic acids or their anhydrides to drying and / or semi-drying oils and / or their Fatty acids and / or resin acids and / or partially hydrogenated resin acids and / or esters of the aforementioned Acids with polyhydric alcohols as the sole binder in aqueous coating compositions for the electrophoretic application process. 40 Publications considered:
German Auslegeschrift No. 1036 426;
Belgian Patent No. 633 074;
British Patent Nos. 500,349, 925,038;
U.S. Patent No. 2,414,712;
Farbe und Lack, 1964, pp. 271 to 279;
Panit Technology, 1963 (December), pp. 13-23. 809 574/442 4.68 Bundesdruckerei Berlin