DE1221748B - Air-drying coating agent - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. CL:

C09d

German KL: 22 g -10/01

Number: 1221748

File number: D31168IVc / 22g

Filing date: July 27, 1959

Opening day: July 28, 1966

The invention relates to aqueous emulsions which form air-drying coatings and are based on Styrene-butadiene copolymers containing acid groups.

From the German Auslegeschrift 1011 548 mixed polymer emulsions for coating purposes are known, those made of elasticizing vinyl compounds, ζ. B. butadiene, in amounts greater than 30 percent by weight, non-elasticizing vinyl compounds, ζ. B. styrene or acrylonitrile, in ίο Amounts of less than 70 percent by weight and half-esters of «, / I-ethylene carboxylic acid derivatives, e.g. B. Maleic acid half-esters, in amounts of about 1 to 20 percent by weight, based on the total amount of the monomers. US Pat. No. 2,894,857 describes coating compositions which consist of latexes of copolymers of dienes, styrene and an unsaturated acid. To In the examples of the latter publication, the minimum amount of acid monomers is about 30%.

It has surprisingly been found that the adhesiveness of such coating compositions on metal and paper can be increased significantly when the acid monomer content is 10 percent by weight does not exceed the total amount of monomers. According to the invention, air-drying coating agents are used based on aqueous emulsions of styrene-butadiene copolymers containing acid groups proposed, which are characterized in that they are made from an aqueous latex of a copolymer from 2 to 10 percent by weight of a monoethylenically unsaturated carboxylic acid, 30 to 50 percent by weight Butadiene and 48 to 68 percent by weight of a monomer or monomer mixture, which is composed of 10 to 100 percent by weight of an alkenyl aromatic monomer such as styrene and 90 composed of up to 0 percent by weight of acrylonitrile.

Although any copolymerizable diolefin can be used in the polymerization approach, butadiene is preferably used. Butadiene is cheap and readily available, and those made from it Copolymers have excellent properties. When using substituted butadienes no additional benefits are given to the crowd.

As alkenyl aromatic monomers, all aromatic compounds can be used, which am Aryl nucleus carry monoethyl unsaturated substituents. Typical examples of such monomers are styrene, tert-butyl styrene and vinyl toluenes. the end Of these, styrene is preferably used for reasons of economy and accessibility. Up to Air-drying coating agent

Applicant:

The Dow Chemical Company,

Midland, me. (V. St. A.)

Representative:

Dr.-Ing. H. Ruschke, patent attorney,

Berlin 33, Auguste-Viktoria-Str. 65

Named as inventor:

John Francis Vitkuske, Midland, Mich. (V. St. A.)

90 percent by weight of the alkenyl aromatic monomer can by acrylonitrile to form a quaternary polymer are replaced. All attempts at making latices in which the entire Styrene had been replaced by acrylonitrile were unsuccessful.

It has been found that the acrylonitrile has a small influence on the pigment binding capacity, on the adhesive strength or on other properties of these polymeric latices.

The ethylenically unsaturated acid derivative can be selected from various compounds be like from carboxylic acids, sulfonic acids and their anhydrides. The condition is that the acid derivative with the other monomers is copolymerizable and that it is an acid or hydrolyzable to an acid is. Typical examples of these derivatives are itaconic acid, acrylic acid, vinylsulfonic acid, vinylbenzoic acid and isopropenylbenzoic acid.

The proportion of the diolefin is 30 to 50 percent by weight of the total weight of the monomers used. If less than 30% by weight of the diolefin is used, a latex is obtained which is not film-forming.

The latexes can be prepared by known processes for polymerization in aqueous emulsion. In a typical process, the monomers in an aqueous solution of about 0.05 to 5 ° / ₀ be a polymerization catalyst such as potassium persulfate, and from about 0.05 to 5 weight percent of a pH-stable surfactant, which can emulsify the monomers dispersed . Such surfactants are known in large numbers. The polymerization is started by heating the emulsified mixture to a temperature

609 607/367

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temperature between about 30 and 70 ° C and by fillers. Thereby a more uniform and permanent-sustained the selected temperature will continue to color and fill at a lower temperature. After the polymerization, the desired likelihood of leaching of the color-conversion of the monomer to the polymer or filler achieved.

has been reached, the latex is removed for the purpose of removal any pre-separation filtered and can then surfaces well suited, although they are in the same way for storage by adding a small amount, also for covering paper or similar dimensions known stabilizing agents stabilized materials are useful. You can use roller, will. Brushing, spraying or immersion processes or after a

The copolymerizable acid is then applied in an effective other known coating process

samiest when they become poly- close to the surface of the latex. The thin coatings obtained are for the

merisate is arranged. The acid can therefore most purposes satisfactorily. If something stronger

after the initiation of the polymerization, coatings are to be produced that are added

will. To achieve the desired coating emulsions with a small amount of a hydro-

properties is less 15 philic colloids in this working process, e.g. B. cellulose ethers, are thickened,

copolymerizable acid as required then The coating agents of the present invention

if all of the acid is already at the beginning of the poly- can form an adhesive, high-gloss underneath-

merization approach is added. Regardless of the broken coating being air-dried,

whether the acid is added before or after the bump. This is compared to the corresponding styrene but-

has been, the polymer has the above ao tadiene latexes an unexpected result, the purpose

functional properties. Achieving an impermeable coating

The coating latices of the present invention must be fired. Of course you can

require fewer emulsifiers than those previously used, and these coatings may also be baked on

knew styrene-butadiene latices. As a result, will be, which shortens the drying time significantly

significantly less foam is formed in these latices. 25 will.

The latices also have, in comparison with known ones, the coatings obtained can according to conventional Styrene-butadiene latexes are an unusual resistant process and are printed on and have a distinctive feature. When latices using mechanical devices recorded water resistance. If the Mixed and worn on, the mechanical coatings when wet is from clear to opaque-resistance of great importance. 3 ° can visually change, then the protection is off For practical reasons, the polymer strength is not reduced, and the bond between body content of the latices is essential. Latices, the coating and the backing will even be elevated less than 20 percent by weight polymeric solids temperatures not weakened so that they are included for sheet metal uneconomical to manufacture, to store cans that use the common washing and sterile and to be transported, if the latex are subjected to considerably more 35 sizing processes, are suitable, than 50 percent by weight of the polymeric solid constituents That a copolymer with hydrophilic sides contains it is usually towards storage and groups towards a copolymer that is more mechanical Shear forces sensitive and cannot contain previous groups, an increased water time can be precipitated. The thickness of the coating will have a slight strength, is a completely unexpected result, due to the polymer solids content of latex 40 The advantages of the coating agent and the resulting * regulated. The covers provided are made up of the following he *

In order to achieve the best of film formation, self-explanatory examples will be apparent in which all

shanks, the largest part of the particles should be individual parts and percentages are weight units,
diameter between about 500 and 2500 Ä units

to have. If most of the particles have an extra- 45 Example
half of this size is the latex

during storage and mechanical processing, an aqueous polymer latex was

processing is less resistant and has a lower film ion polymerization of 30 ° / ₀ styrene, 40 ° / ₀ butadiene,

forming ability as a latex the particles of which the 25 ° / ₀ acrylonitrile and 5 ° / ₀ of itaconic acid at a

have specified size. When coated by Me- 50 temperature of 50 ° C produced. After filtering

Tallen has been found to have trier within this for the purpose of removing the pre-separation

In the lower particle size range, the latex has a pH of 2.5. He was about a

For various coating purposes, the sample piece cleaned with a cleaning agent is off

incorporation of certain additives into the latex - purpose-made cold-rolled automotive steel flow

moderate. Typical examples of such additives are air-dried for 55 and 7 days. The coating had

Metal chelants, pigments and stabilizers - a thickness of about 0.0127 mm. He would have a high

agents. The coating compositions of the present gloss, did not stick and had excellent

Invention may contain such additives that for hardness and adhesive strength. The coated specimen

a specific purpose other than film formation could be bent without loss of adhesive strength *

can be added. These additives are used with the 60 The coated specimen has been in for 24 hours

Latex mixed according to standard mixing methods. The desalinated water is immersed and then examined.

Additive can therefore be finely crushed and in the latex there was a slight discoloration, but none

are introduced, or an aqueous emulsion of the loss of adhesive strength is noted.

The additive can be mixed homogeneously with the latex. A test piece coated in the same way was produced

will. 6g baked for 30 minutes at 135 ° C and then in

One advantage of the coating compositions according to the invention is immersed in water. After 7 days of immersion it became there is a slight discoloration in the improved binding of the film-forming components, but no loss of the adhesive components with solid additives such as pigments and strength determined.

Example 2

The latex produced in Example 1 was processed as follows: To 100 parts of latex solids were added 0.1 part of cobalt acetate in a 3.3 ° / _o aqueous solution of Isooctylphenylpolyglykoläther added as a surfactant and 20 parts of a pigment comprising 90 parts Eisenoxydgelb, I ¹ J contained ₂ parts of dimethylhexynediol and 2 parts of dinaphthyl methanesulfonate surfactant in 90 parts of water. This dispersion was sprayed onto steel coupons and air dried for 3 days. A very glossy coating with good adhesive strength and hardness was obtained. The adhesive strength was not impaired when the test piece was bent. The coating was resistant to light gasoline and white spirit. After 48 hours of exposure to a salt spray, only a slight loss of adhesive strength was observed, which, however, returned when exposure was ceased.

For comparison, a latex was made from 60% styrene and 40% butadiene with the same solids content, which was then processed in the manner indicated above. After spraying and air drying the coating was cloudy and showed poor adhesive strength. After immersing for 15 minutes in water the coating could easily be peeled off the specimen. After 16 hours of immersion the stoved coating could be peeled off the specimen in water.

Example 3

The latex produced in Example 1 and adjusted to a pH of 5.5 with ammonium hydroxide was flowed over a tin test piece cleaned with a detergent and started for 30 minutes air dried. The coating was 0.0127 mm thick, had a high gloss, was clear, and white good adhesive strength. The coated coupon was heated to 135 ° C for 5 minutes and then 30 minutes immersed in boiling water for a long time. The coating turned somewhat whitish, but did not show any Decrease in bond strength and no bubbles. 5 minutes after removing from the boiling Water, the coating returned to its original state.

Example 4

The latex produced in Example 3 was covered with 1.6 ° / ₀ ethylenediaminetetraacetic acid to the latex solids, mixed, were coated whereupon Zinnprobestücke as described in the Example 3 with it. The coated test pieces were baked for 5 minutes at 135 ° C., then immersed in boiling water for 30 minutes and then examined. A test piece was bent around a 2.54 cm mandrel without loss of adhesive strength. Another specimen was subjected to a 4.53 kg Gardner drop ball impact test without damage to the coating.

Example 5

The latex from Example 1 was processed by mixing 100 parts of solid substance as a latex in a 20 ⁰ / o aqueous dispersion were dispersed carbon black. The dispersion was sprayed onto an anodized magnesium casting and air dried. The coating was 0.0127 mm thick, had a high gloss and good adhesive strength, and was tack free. The coated casting was immersed in tap water for 24 hours without loss of adhesive strength. The coated casting was also immersed in boiling water for 1 hour with very little loss of adhesive strength, but which was regained 30 minutes after withdrawal.

Example 6

Various latexes were made from styrene, butadiene, and acrylic acid in the following percentages manufactured:

Styrene

Butadiene ..
Acrylic acid

60
40

55

40

50
40
10

A pigment dispersion of clay coated dyes was made into each latex in a proportion of 100 parts pigment solids mixed to 15 parts latex solids. The homogeneously mixed Dispersion was applied to bleached sulfite paper using a wire-wound rod and then air-dried for 24 hours.

The pigment binding was determined with a Warren print tester, in which a coated paper a metal plate is attached and an inked cylinder with the coated paper is brought into contact at increasing speeds until a speed has been reached in which the ink partially removes the coating from the paper. Each of the crowds was with one compared to commercially available styrene-butadiene paper-coating latex. In this comparison it turned out the masses A and B far worse than the standard mass. The masses C, D and E were the commercial dimensions equivalent or slightly better. Latices with similar properties were produced, by replacing acrylic acid with itaconic acid, maleic acid, fumaric acid or cinnamic acid.

Example 7

Different latices were made in the following monomer composition:

F. G H I. J Styrene 55
0
5
40 53
2
5
40 30th
25th
5
40 10
45
5
40 30th
40
0
40 Acrylonitrile
Itaconic acid Butadiene

The latexes were made with 5 percent by weight of a commercially available anionic emulsifier. After polymerizing and filtering to remove the preseparation, the latices had excellent mechanical resistance. Coatings on automotive steel showed excellent Adhesive strength.

Following the procedure given in Example 6 A pigment dispersion was prepared and homogeneously mixed with each latex, whereupon the obtained Dispersions were applied to paper. the

Pigment binding was determined using the Warren Print Tester with the following results, which include the Speed of the plate in 0.30 m per minute with a printing pressure of 35 kg below the Specify spring balancer B. Less pick-up is the point at which the plate starts picking up the Ink from the paper begins, which can be seen through pinholes. Bigger uptake is the point at which the ink is completely removed from the paper. The greater the speed is, the greater the adhesive strength of the coating.

latex
F j GIHII 500
no no
no 480
600 J Speed up to the lower take up ....
Speed up to larger take-up 550
no 380
440

From these results it can be seen that the latexes have approximately the same adhesive strength.

Attempts to replace all of the styrene with acrylonitrile always resulted in no useful latex.

Example 8.

Latices were made with the following approach:

135 parts by weight of water,

'. 2 parts by weight of a sodium salt of an alkylaryl polyether sulfate as surface-active
Middle,

* 0.7 parts by weight of the diocryl ester of sodium sulfosuccinic acid, as a surfactant,

- ^r 0.5 parts by weight of potassium persulfate and

100 parts by weight of those listed in the table below Monomer mixtures.

The polymerization was set in a conventional manner by heating the components at 50 ⁰ C in motion and maintained for 40 hours under movement in a tumbler at 12 revolutions per minute at this temperature. After the polymerization, each latex was filtered through fine paint filters. A pigment dispersion of clay coated dyes was mixed into each latex in a ratio of 100 parts pigment solids to 15 parts latex solids. The mixed dispersion was applied to bleached sulfite paper using a wire wound rod and air dried for 24 hours. Pigment binding was determined using a standard test method

zo an I.G.T. print tester. With this test method is the coated paper with a platen, which is coated with a standard printing ink, brought into contact. The speed of rotation of the roller is continuously accelerated until a predetermined one Amount of paper covering has been removed or until the paper backing is destroyed. The results are reported as the speed of the pressure roller in meters per second. These results are listed in the table in the column "Dry removal".

In a modification of the detachment attempt, before the paper was brought into contact with the Pressure roller placed 3 drops of water on the paper and distributed with a rubber sponge.

The test was then carried out as described above. These results are in the column "Wet peeling" is listed in the table. For one

For a useful coating approach, the wet release should be 15 or more.

Tabel!

example Styrene Butadiene Itaconic acid Acrylic acid Solid
salary Dry
replacement
(m / sec) Wet peeling
(m / sec) comparison 10 60 40 - - 40.0 140 6th 11 45 40 - 15th 39.3 74 12th 12th 40 40 - 20th 40.5 coag. * - 13th 30th 40 - 30th 36.3 coag. * - 14th 40 40 10 10 35.0 coag. * - According to the invention Crowds 15th 58 40 2 - 39.4 213 15 to 18 16 55 '40 5 - 37.8 213 15 to 18 17th 58 40 2 39.3 171 21 18th 55 40 - 5 40.4 146 18 to 21 19th 50 40 - 10 39.8 117 21 20th 56 40 2 2 38.4 213 18th 21 50 40 5 5 36.9 213 21 22nd 55 40 5 g methacrylic acid 40.3 134 15 to 18

: when added to the pigment dispersion.

It should be noted that if the quantity of acid monomers is greater than 10 ° / ₀ (z. B. in the masses that "under the caption comparison" are listed), the latex composition does not make more coating that the minimum requirements for Offset printing.

The latices listed above were also flowed onto cold rolled steel plates and air dried for 24 hours. If the concentration of acidic monomer in the polymer was greater than 15%, the plates rusted and the coatings were discontinuous with pinholes and cracks. Furthermore, were the coatings that were prepared from compositions containing more than 10 ° / contained ₀ acid monomer, sensitive in water to water upon immersion of the dried sheets, as evidenced by whitening, as the coatings containing less than 10 ° / ₀ acid monomer contained.

Example 9

Various latices were made using the following approach:

100 parts of water,

1.1 parts by weight of sodium lauryl sulfate as a surface-active agent,
1.22 parts by weight of the dioctyl ester of sodium ^ao

sulfosuccinic acid as a surfactant, 0.7 parts potassium persulfate,
0.8 parts of sodium sulfate,
95 parts per million versenic acid and
100 parts of the monomer mixtures listed in the table below.

The polymerization was carried out according to the procedure described in the previous example. After the polymerization, each latex was filtered. A clay pigment dispersion (for paper coating purposes) was mixed with each latex in a ratio of 100 parts clay to 24 parts latex to give a composition having a total solids content of 60 ° / ₀ . The mixed dispersion was applied to bleached sulfite paper with a # 10 wire wound rod to give a coating weight of about 9.76 grams per square meter.

The dried coated papers were made according to the dry release procedure mentioned in Example 8 checked.

The coated papers were also tested by a wet wipe method. With this test method was cut with lacquer-coated black photographic paper into 16.5 cm strips and with a white pencil divided into sections about 5 cm wide. The coating to be tested was along one Section of black paper and placed on the coated paper 3 drops of water at intervals applied from about 2.5 cm. A finger was placed on the water stain without applying pressure pulled across the black paper by the coated paper. This procedure was with everyone Water drops repeated. The amount of coating that goes from the coated paper to the black Paper transferred was rated as zero, small, medium, or large. The results are in the following Table summarized.

Table II

example Styrene Butadiene Fumaric acid Acrylic acid Dry detachment Wet wiping attempts comparison 23 47 47 4th 2 122 middle 24 42.7 51.3 4th 2 91.5 Big 25th 43.6 52.4 3 1 122 middle According to the invention Crowds 26th 48 48 3 1 183 Small amount 27 50.2 45.8 3 1 183 zero

Claims (1)

Claim: Air-drying coating compositions based on aqueous emulsions containing acid groups Styrene-butadiene copolymers, characterized in that they consist of an optionally pigmented aqueous latex of a copolymer of 2 to 10 percent by weight a monoethylenically unsaturated carboxylic acid, 30 to 50 percent by weight butadiene and 45 50 from 48 to 68 percent by weight of monomers ^ or A mixture of monomers consist of 10 to 100 percent by weight of an alkenyl aromatic Monomers such as styrene and 90 to 0 percent by weight acrylonitrile. Considered publications:
German Patent No. 908 652;
German Auslegeschrift No. 1 011 548;
U.S. Patent No. 2,894,857. 609 607/367 7.66 © Bundesdruckerei BerliD