DE1162731B - Process for the production of a multilayer paint system with top layers of polymethacrylic acid methyl ester on metallic surfaces - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Boarding school Class: B44d

German class: 75 c -5/04

Number: 1 162 731

File number: P 14170 VI b / 75 c

Filing date: May 24, 1955

Opening day: February 6, 1964

Polymethacrylic acid methyl ester lacquers are extremely weather resistant, especially pigmented ones Condition, very glossy, but its protective effect on metallic surfaces, in particular those that are exposed to the weather, such as steel motor vehicle housings, are insufficient, especially against rusting. Therefore, the metal surface must be applied before applying the polymethacrylic acid methyl ester paint be provided with a rust-proof primer beforehand. The primer must adhere well to the metal surface and at the same time a good surface for the applied Paint layers result. The oven-drying primers are used because of their better ones Properties preferred to air drying. The primed item is then sanded, to achieve a smooth surface for painting. When grinding irregularly shaped Parts, like doors and fenders, will apply the primer coat to the protruding parts of the Workpiece is often sanded down to the bare metal surface or the primer layer is so weakened that that it can no longer exercise its protective effect. Such positions have to be included again be covered with a primer layer, but it is not advisable to use the one originally used oven drying, but an air drying agent used to keep the The painting process is not interrupted. This primer used for post-priming should Adhere well to both the bare metal surface and the existing primer layer and result in a perfect surface on which the polymethacrylic acid methyl ester paint adheres well with a flawless surface.

Often it is a matter of touching up damaged, painted objects. For this purpose, the damaged area must be ground, if necessary after bulging, welding or the like, in order to remove the lacquer layer and the base layer. For touch-ups you have to use air-drying primers and lacquers, because the finished parts are oven-dried, ζ. Β. the body of a motor vehicle, is not possible because the textile and rubber components burn and the lubricant would leak. In these cases, too, the primer and the paint must adhere firmly to the metal or the existing paint layers, and the primer must produce a flawless surface on which the methyl polymethacrylate paint sets. The usual primers, sub-processes for producing a multi-layer paint system with top layers are suitable for such repair work
Polymethacrylic acid methyl ester
metallic surfaces

Applicant:

E. I. du Pont de Nemours and Company,

Wilmington, Del. (V. St. A.)

Representative:

Dr.-Ing. A. ν. Kreisler, Dr.-Ing. K. Schönwald
and Dr.-Ing. Th. Meyer, patent attorneys,
Cologne 1, Deichmannhaus

Named as inventor:

Ronald John Sheppard, Springfield, Pa.

(V. St. A.)

Claimed priority:

V. St. v. America, June 4, 1954 (No. 434 665)

and top coats of the usual alkyd resin lacquers, amine-aldehyde resin lacquers or cellulose nitrate lacquers not as intermediate layers for top layers made of methacrylic acid methyl ester resins, because these do not adhere adequately, the top layer flakes off and becomes cracked.

This object is achieved according to the present invention, which provides a method for producing a multi-layer paint structure with top layers of polymethacrylic acid methyl esters on metallic Surface concerns, which is characterized by the fact that you have the metal surface or an existing one sanded primer with a primer

a) an organic film former from 5 to 70%, preferably 25 to 50%, cellulose nitrate, 5 to 75%, preferably 20 to 55%, shellac, 0 to 40%, preferably 3 to 20%, polyvinyl butyral and 0 to 50%, preferably 10 to 40%, plasticizers,

409 507/357

3 4

b) 10 to 180% of a pigment, based on the total weight of Example 1, of the organic film former a) and ^ ^us i ° lg ^{en (} l ^en components was a primer

preparation means according to the invention:

c) a solvent for the film formers

• t- λ c j ■ jrr ⁵ part I parts and on the preferably in the air

dried coating a varnish made of polymeth- »/» "- grade collodion wool in

acrylic acid methyl ester with a relative viscosity of 25% solution 2.71

1.117 to 1.196 in one or more layers of titanium dioxide 4.56

brings up. ok

It is known that the butyral resins with shellac part II

are compatible. On the other hand, they are not compatible with V4 "grade collodion wool

with low-viscosity, ester-soluble collodion wool 29 6% solution 3 03

and only to a small extent with alcohol-soluble i / ". _gr ädige collodion ₂

Collodion wool. The three-part 15 23% solution according to the invention 16 80

bination was not known and one knew ,, - ",. _T .. _ ',', 7, ' 7'. '

especially not that this mixture is a favorable ⁴⁵ ° ^{/ ol} S ^e * r ° ^sun S. _A ^v ° ⁿ Sf ^{hellack in}

Lich link between metallic surfaces denatured ethanol 17.39

and polymethacrylic acid methyl ester lacquer layers - 15% solution of polyvinyl

represents. ao butyral in 60 parts of methanol

Under a lacquer cellulose nitrate is a lacquer ^and 40 parts of toluene 18.20

collodion wool, e.g. B. a Ε-wool or Α-wool, to paint solvent 17.31

understand how to manufacture nitrocellulose varnishes

is used. Apart from that used as a binder for the polyvinyl butyral had a 6% methanol top layer The polymethacrylic acid methyl solution used had a viscosity of 13 to 18 cP at 20 ° C. esters are also copolymers of methacrylic acid, the viscosity, of the collodion methyl ester with others with them mixed polymeric wool solutions in the lacquer solvents is after To understand sate forming substances, which is the main ASTM D-301-33, formula A, determined and is thing contain methyl methacrylate, as well as explained in more detail below.

Mixtures of such polymers with mixed poly-30 Part I were made in the usual manner in the paint mill

meren. The polymethacrylic acid methyl ester lacquers are ground to a homogeneous, smooth dispersion,

len liquid mixtures of methacrylic acid methyl- then the substances of Part II were successively

ester polymers as the main film-forming added and the whole thing intimately mixed. The get-

the component with customary pigments and solder contained liquid coating agents as film-forming agents

solvents, the plasticizers, inhibitors, 35 34% lacquer cellulose nitrate, 49% shellac and 17%

Dispersants, leveling agents, and the like, polyvinyl butyral. The pigment content was 28.5%,

may contain. Under layers or films related to the total organic film formers, are the dry coatings of polymethacrylic acid

To understand methyl ester lacquers, as they are according to Examples 2 to 6 or multiple applications on a suitable 40

Support can be obtained after drying. According to Example 1, modifying the

Unless there are quantitative ratios, all quantitative data relate to the following according to the invention

otherwise noted, on weight quantities. Primer made:

3 example 5 6th 2 3.05 4th 3.57 1.68 2.19 5.12 1.81 6.01 2.84 3.68 1.80 3.04 2.00 4.14 3.70 44.80 3.62 11.08 5.16 - 10.37 20.07 35.21 7.66 19.20 10.80 2.46 12.07 24.85 22.20 24.06 21.75 30.06 53.67 49.03 64.9 »/ 0 47.25 18.6% 28.3% 12.1% 26.1% 54.1% 73.1% 34.4% 63.5% 9.0% 11.6% 8.3% 37.3% 24.4% 28.6% 34.3% 28.2% 28.4% 27.0% 32.0%

TeUI

V2 "grade collodion wool in 25% strength

solution

Titanium dioxide

Part II

V / '- grade collodion wool in 29.6% strength

solution

W'-grade collodion wool in 23% strength
solution

45% shellac solution

15% polyvinyl butyral solution

Paint solvent

Film former content

Lacquer cellulose nitrate

shellac

Polyvinyl butyral

Pigment content, based on total film former

10

Example 7

Another primer according to the invention was prepared from the following ingredients:

Part I ^parts

Benzyl butyl phthalate 2.97

Methyl ethyl ketone 7.68

Methyl isobutyl ketone 7.68

Titanium dioxide 5.04

Barite 24.97

Talc 3.15

Carbon black 0.14

Part II

V / '- grade collodion wool in

29.6% solution 22.00

45% alcoholic shellac solution 15.84 50% resin acid glycerol ester

Solution in toluene 6.20

Benzyl butyl phthalate plasticizer 4.33

The mixture was processed according to Example 1. The organic film formers consisted of 27.1% _ag lacquer cellulose nitrate, 29.6% shellac, 30.4% plasticizer and 12.9% resin acid glycerol ester. The mass contained 139% pigment, based on the total amount of organic film formers.

Manufacture of primers

of the previously known kind

For comparison purposes, the following three air drying primers were made, the corresponded to the usual types used for foundation and repainting of automobile body parts previously used:

Middle A parts

Lacquer cellulose nitrate 83.3

GIy modified with 35% linseed oil

cerin phthalate resin 18.5

Dibutyl phthalate 18.5

Castor oil 4.6

Medium B

Lacquer cellulose nitrate 28.8

Shellac 42.4

Linseed oil stand oil 14.4

Tricresyl phosphate 14.4

Middle C

Glycerine phthalate resin modified with 45% soybean oil 100.0

For comparison, test panels were produced as follows:

Clean sheet metal from body parts, some with a bare, some with a phosphated metal surface were coated with various primers I to VIII listed below. In some Cases an intermediate layer was applied to the primer. There were two of each attempt Test panels made, one of which is exposed to outdoor weathering and the other in Laboratory was examined.

The primers were pigmented in a manner suitable for the metal primer. The coatings were applied in a suitable degree of liquid by spraying the agent in such an amount, that the dried films were about 12.5 microns thick. The films were then made as follows is described, dried. The primers contained the following film formers solvent-free substance calculated.

40

45

Primer I Parts GIy- modified with 55% linseed oil cerin phthalate resin 59.3 Phe modified with 50% linseed oil molformaldehyde resin 40.7 The reason was 30 minutes Baked in at 121 ° C. Primer II Parts Resin modified with 65% linseed oil acid-glycerine resin 92.8 Linseed oil stand oil .... 7.2 The primer was 30 minutes baked at 188 ° C. Primer III Parts GIy modified with 43% soybean oil cerin phthalate resin 11.2 GIy- modified with 35% soybean oil cerin phthalate resin 68.4 Butyl urea formaldehyde resin .... 20.4 Baked for 45 minutes at 135 ° C. Primer IV Parts GIy modified with 43% soybean oil cerin phthalate resin 100.0 4 hours at room temperature air dried. Primer V Parts GIy modified with 52% soybean oil cerin phthalate resin 100.0 15 minutes in the oven at 338 ° C burned. Primer VI Parts GIy modified with 65% linseed oil cerin phthalate resin 86.8 Linseed oil stand oil 13.2 Baked for 30 minutes at 121 ° C. Primer VII Parts GIy modified with 43% soybean oil cerin phthalate resin 21.7 With 24% linseed oil and 24% wood oil modified glycerine phthalate resin 57.5 Butyl urea formaldehyde resin .... 3.0 Lacquer cellulose nitrate 12.8 Dibutyl phthalate 5.0 Baked for 30 minutes at 121 ° C. Primer VIII Teüe GIy modified with 43% soybean oil cerin phthalate resin 2.0 GIy- modified with 35% soybean oil cerin phthalate resin 66.0 Lacquer cellulose nitrate 21.4 Dibutyl phthalate 10.6 Baked for 30 minutes at 149 ° C.

7 8

The wells sprayed with primers I to VI were applied to one or more of the

Sheets were sprayed with the following repair points prepared with the following intermediate layer means, one of the primers suitable for spraying viscosity, so that the agent according to Example 1 to 7 and the known after 5 minutes of drying at room temperature means A to C sprayed, the film thickness on the door a film of 100 microns thickness was obtained: 5 tapered lacquer edges according to the known spring edges injection molding technique so decreased that the excess interlayer Teüe _FOR g _of (J _6n edges is tapered and a Vs "was -grädige lacquer collodion cotton uniform bleed coating as a whole.

in 40% solution 28.4 The with the products according to Example 1 to 7

Dicyclohexyl phthalate 3.7 ^{10 ur} * d the remedies A and B repaired sheets

Lacquer solvent 679 were now 10 minutes, which with the agent C

* 'Improved sheet dried in the air for 4 hours.

Half of each primed ^floodplain was then covered with fine sheet metal and the free area was lightly sanded over with sandpaper. Then, polymethacrylic acid methyl ester varnish of suitable viscosity, finally the top varnish of polymethacrylic acid viscosity was sprayed in such a way that, after drying, a methyl ester was applied in such a way that it was formed over the outline film with a thickness of 50 microns. The metal sheets of the repaired area went out so that they would dry quickly for 20 minutes at 82 ° C - ^{no or barely} noticeable so that dry, hard coatings ²⁰ corresponds dried.

stood. The top coat had the following composition- ^The repaired areas of all sheets, so the

set: ^with the invention and the known

Primers treated were in the Aus-Polymethacrylsäuremethylester topcoat Teüe see the gloss and the hardness flawlessly and it

Polymethacrylic acid methyl ester 29.74 25 no differences were found by visual inspection.

Dibutyl phthalate 11.93 recognizable.

Titanium dioxide 716 ^ ' ⁿ ^ ^atz ^ ^er test sheets were now on the

^ 'Repairs crosswise over a length of

^{Carbon black} ° ^'07 each 5 cm vertically through the coating except for the

Ferrite yellow 0.98 ₃₀ Metal scratched in the shape of an X, with a CeIIu-

Red iron oxide 0.12 loose adhesive tape pressed and this with a

Toluene 25 00 pulled off, causing loose layers of the over-

Y, τ 2500 zuges were removed so that it could be seen how

y 'the individual layers on top of the ones below

The polymethacrylic acid methyl ester had a relatively adhesive strength.

tive viscosity of about 1.142, according to the formula ^For the sheet treated ^{with agent c}

the top layer was removed with the adhesive tape

(A) Polymer solution outflow time cracked. The layer C adhered to the cover

(B) The solvent layer used is insufficient. All other sheets

40 the primers adhered well to the sheet metal and

is determined, the outflow times according to the various overlying layers. Method according to ASTM D-445-46T, method B The sheets were then cracked

(See Zerbe, "Mineral oils and related products", coatings checked by putting a quick blow on them Berlin, 1952, p. 52), were determined by using a heavy sharp object, e.g. B. In place of the oil (A) a solution of 0.25 g of the poly-45 with a small chisel was applied. It could methacrylic acid methyl ester in 50 ecm ethylene dichloro observed what force was to be used, rid and (B) a sample of the ethylene diamine used to knock a piece out of the coating Chloride was used. The determinations and how big this piece was. With this blow at 25 ° C. in a modified Ostwald-Vis test showed those with the inventive Kosimeter No. 50 carried out. 50 primers according to example 1 to 7 coated

The polymethacrylic acid methyl ester lacquer was superior to means A to C, by grinding the pigment with the polymer. The second set of panels was eight in Florida

exposed to the elements until a smooth, uniform di- months. In all cases spersion made. the original paintwork remained fixed, shiny

After the sprayed metal sheets have cooled down to space zend and relatively crack-free. The ones with the invent temperature was in the middle of the sheet from the paint according to the primer according to Example 1 layer a point with a diameter of up to 7 repaired points also remained firm, 38 mm by means of sandpaper except for the metal surface shiny and relatively crack-free and showed ground in such a way that there are no noticeable differences on either side of the dividing line between the lacquered and the primer 60 closing original lacquer. With th half extended and the sanding point on the edge of the known means A to C primed Ausvon wafer-thin, gradually to full strength the improvement areas were badly cracked, so that Layers of varnish passed over, so that after renewing them from the surrounding original paintwork No edges were painted and the outline stood out so clearly that they were suitable for the prakder sanded point was no longer recognizable. 65 tables were unusable.

The sheets obtained in this way offered a large number. It follows from these test results that the

of the known primers for testing the coating according to the invention systems are suitable repair points. are far superior.

The collodion wool solutions listed in the examples can largely vary in their viscosity vary. All lacquer wools, i.e. lacquer cellulose nitrates, with viscosities between Vs "are suitable up to 1 ", which can also contain small amounts of higher viscosity components, e.g. up to 50" or 100 ". A V8 "-graded collodion wool has a viscosity of around 20 cP, while a 100" -graded collodion wool a viscosity of about 38,000 cP in 12.2% solution according to the ASTM method D-301-33, Formula A. With these cellulose nitrates, results similar to those obtained after Examples achieved. Vs "to V2" grade collodion wool with a viscosity of 20 to 150 cP to prefer.

The concentration of cellulose nitrates in the primers according to the invention can also be varied within wide limits, e.g. B. from about 5 to 70 ¹ Vo, based on the total weight of organic film formers, fluctuate. The concentration of cellulose nitrate is preferably 25 to 50%, calculated on the total organic film-forming agents.

All types of shellac suitable for lacquer purposes can be used for the lacquer structure according to the invention However, the pure, especially the wax-free, bleached shellacs are to be preferred. The shellac content can be varied within wide limits, e.g. B. between 5 and 75%, on the total film formers related, fluctuate. The shellac content is preferably between 20 and 55%.

All polyvinyl butyrals suitable for paint purposes can be used in the primers according to the invention used, which usually have viscosities of about 10 cP (in 6% methanol solution) up to 110 or 12OcP (in 5% ethanol solution).

The polyvinyl butyral content of the paint system according to the invention can be within wide limits, z. B. between 0 and 40%, based on the total weight of organic film formers, fluctuate. If the content is above 40%, the solids content of the agent must be avoided in order to avoid excessive viscosity be kept so low that a single spraying results in too thin films. That is avoided if a lower viscosity is used at higher polyvinyl butyral concentrations. The polyvinyl butyral content is expediently 3 to 20% of the total organic weight Related to film formers.

In addition to the benzyl butyl phthalate listed in Example 7, plasticizers can be used according to the invention for example also dibutyl phthalate, dicyclohexyl phthalate, di (2-ethylhexyl) phthalate, the diphthalic acid diesters of ethylene glycol monomethyl or monobutyl ether, tricresyl phosphate, triphenyl phosphate, Toluene ethyl sulfonamide, butyl phthalyl butyl glycolate, methyl phthalyl ethyl glycolate, glycol sebacate, Polyethylene glycol sebacate can be used. The plasticizers can not only be used in Example 7, but can also be added to the mixtures according to Example 1 to 6 in amounts of up to 50%, and they give primers and lacquer coatings of similar properties to those in the examples 1 to 7 described. The addition of plasticizers is preferably 10 to 40% of the total weight of organic film formers.

As can be seen from Example 7, the inventive Other organic film formers are also added to paints, preferably those which dry to hard films after the solvent has evaporated, such as rosin acid glycerol esters, Rosin, hydrocarbon resins and phenolic resins. The additives of such resins should, however do not exceed 15%, calculated on the total weight of organic film-forming agents.

The usual lacquer solvents for nitrocellulose, shellac can be used for the lacquers according to the invention and polyvinyl butyral or also solvent mixtures or mixtures with hydrocarbon thinners be used. These include esters such as ethyl acetate, butyl acetate or ethylene glycol monoethyl ether acetate; Ketones such as acetone or methyl ethyl ketone; Alcohols such as ethanol or isopropanol; Ethers, such as ethylene glycol monobutyl ether, and hydrocarbons, such as toluene, xylene or Mineral spirits.

Pigments for the agents according to the invention, for example, titanium dioxide, iron oxide, zinc chromate, Gas black, Berlin blue, phthalocyanine blue or green, barite, chalk, talc, clay, Color pigments, chromite and other pigments or mixtures such as are customary in the paint industry can be used. The pigment addition can be between about 10 and 180%, calculated on the total weight of organic film formers.

The agents according to the invention can be prepared by any suitable method, e.g. B. by spraying, diving, Brushing on, spraying being preferred. The strength of the individual layers of paint should generally be within the thicknesses of 5 to 50 microns commonly used in painting per shift.

Since the paint system according to the invention consists of air-drying substances, drying is expedient by evaporating the volatile constituents at room temperature. The drying however, it can also be abbreviated, e.g. B. by baking or oven drying, adding the sprayed Objects at a higher temperature, e.g. B. be dried from 65 to 95 ° C for 5 to 20 minutes.

The polymethacrylic acid methyl ester lacquers listed as topcoats in the examples represent only a selection. Their composition and proportions can vary within wide limits. In addition to the methyl polymethacrylate listed in the examples, mixed polymers with a lower content of z. B. 2 to 25% of other substances forming copolymers with the methyl methacrylate are used, such as acrylic and methacrylic acid, the C ₁ to C ₄ alkyl esters of acrylic acid, the C ₂ to C ₄ alkyl esters of methacrylic acid, vinyl acetate, acrylonitrile and styrene. A particularly suitable mixed polymer consists, for example, of 98% methyl methacrylate and 2% methacrylic acid.

The viscosity of the polymethacrylic acid methyl ester paints Polymers used is expediently between 1.117 and 1.196, determined by the method listed above, what a Molecular weight from 55,000 to 105,000. Such top coats are in the Belgian patent 538 692. Other top coats that are particularly suitable for spraying are in the Belgian patent 534,685.

409 507/357

The agents described in Examples 1 to 7 are not limited to repair work, but can also be used in general for priming metallic objects of any kind be used. The various coating compounds do not only need to be applied in one layer but you can also put two or more layers of the same remedy on top of each other splash.

The coating agents according to the invention are suitable for touching up damaged, painted metal objects, such as automobile bodies that have a top coat of methyl polymethacrylate topcoat have or should receive. They differ from the means previously used thanks to quick drying at room temperature, excellent adhesion to the metal surface as well as with the top layer, high resistance to abrasion. *

scroll, good elasticity, excellent weather resistance £ _ and especially because of their resistance to cracking.

Claims (1)

Claim: Process for producing a multilayer paint system with top layers of polymethacrylic acid methyl ester on metallic surfaces, characterized in that the metal surface or an existing one sanded primer with a primer a) an organic film former from 5 to 70%, preferably 25 to 50%, cellulose nitrate, 5 to 75%, preferably 20 to 55%, shellac, 0 to 40%, preferably 3 to 20%, polyvinyl butyral and 0 to 50%, preferably 10 to 40%, plasticizer, b) 10 to 180% of a pigment, based on the total weight of the organic Film former a), and c) a solvent for the film formers and on the coating, which is preferably air-dried, a varnish made of polymethac- trlüCU iaul 4UD rUiyiilPL acrylic acid methyl ester of a relative viscosity layers g yfhrinpt. ύ / S Considered publications: Kittel, "Farben-, Lack- und Kunststoff-Lexikon", 1952, p. 663; Chemisches Zentralblatt, 1951, II, p. 3661, para. 8; “Mowital B prospectus” by Farbwerke Hoechst A. G., May 1953, p. 3; Krauss, "Handbook of Nitrocellulose Lacquers". Part 2, 1952, p. 149, penultimate paragraph. 409 507/357 1.64 © Bundesdruckerei Berlin