NO830103L - COLOR PIGMENT FOR PAINTING COMPOSITIONS. - Google Patents

Description

The present invention generally relates to coatings using water emulsion binders. More precisely defined, the invention relates to water emulsion paints that contain a new dye with improved properties that increase the color stability of these paints.

Conventional water emulsion paints are prepared by mixing one or more color pigments in water containing suitable additives such as surfactants, stabilizers, dispersants and thickeners, followed by mixing with film formers such as acrylic resin emulsion, acrylic copolymer emulsion and acrylic resin containing emulsions. An essential requirement for any pigment is first that it must give a clear and appealing color when added to the paint either alone or together with other pigments. In addition, the pigment must be stable so that it keeps the color for a long period of time. Another important requirement is that the pigment should have a very finely divided particle size, generally smaller than approx. 10 right. The fineness of the particles increases the pigment's ability to be easily dispersed throughout the paint mixture during processing and also ensures that the paint will be evenly distributed in a thin layer when applied to a surface without streaks or other defects. The latter requirement is naturally most significant in those cases

where the paint is to be applied by conventional technique with brush, roller or spray.

It is therefore an important object of the present invention to arrive at an improved pigment for use in water emulsion paints. Another more specific purpose of the present invention is to produce an improved water emulsion paint which has good color stability and a relatively high resistance to fading when exposed to sunlight.

According to the present invention, an improved color pigment for use in water emulsion paints has been produced, which comprises manganese manganese oxide (Mn^O^ )-r oil or a material containing manganese manganese oxide fumes as the main ingredient. The Mn^O^ smoke dye is first dispersed in water containing surfactants, dispersants, antifoams, extenders, thickeners, stabilizers, glycols and the like. and is then added to a water emulsion based on acrylic resins or acrylic copolymers. The Mn^O^-smoke dye can make up from approx. 5 to 50% by volume of the total non-volatile proportion of the paint.

The present invention will now be described in more detail with reference to the drawing which is a curve showing particle size distribution for a preferred manganese oxide fume-containing material used as the color pigment.

The present invention is based on the discovery that manganese manganese oxide smoke or a material which predominantly contains manganese manganese oxide smoke in a finely divided state is a new and ideal colorant for use in the formulation of various water emulsion paints. In particular, the Mn^O^ smoke color pigment is particularly useful in those applications where conventional iron oxide pigments have been used in the production of colored water emulsion paint. It has e.g. It has been shown that finely divided manganese oxide smoke when used as a color pigment gives a dark brown or dark reddish brown color similar to, but still clearly quite easily distinguishable from, the brown pigmentation produced by a number of synthetic iron oxide pigments, e.g. yellow, golden brown and red iron oxide pigments. It has also been shown that Mn^O^ smoke color pigment is stable at temperatures up to approx. 600°C, while on the other hand, conventional yellow or yellow-brown iron oxide pigments turn into red iron oxide when heated to approx. 175°C. The Mn-joO^ smoke color pigment can also be produced within a wide range of particle sizes, which approach or are equal to the particle size of conventional iron oxide pigments according to prior art. As mentioned, it is desirable that the color pigment has a very finely divided particle size 1 to make it possible for the pigment to be distributed evenly over the entire paint during its production. In general, the carbon monoxide pigment should have a particle size of less than about 10 right.

As mentioned, the color pigment used in carrying out the present invention is manganese-manganese oxide smoke or it can be a mixture or a material which mainly contains manganese-manganese oxide smoke, e.g. over approx. 60 volume %.

The Mn^O^ smoke in question is most easily produced by passing a jet of oxygen through or across a surface of a molten bath of ferro-manganese. Conventional ferro-manganese produced in a blast furnace or in an electrometallurgical furnace etc. at a temperature of approx. 1200°C or more can contain up to 6% or more carbon. Usually the carbon content is reduced, e.g. to approx. 1.5% by blowing oxygen or a mixture of oxygen and air through or against the surface of the bath of molten ferro-manganese. This is done in a separate vessel containing a melting bath of ferro-manganese which has just been drawn from the melting furnace at a temperature of approx. 1000°C or more and preferably at approx. 1300°C or more.

A method for reducing the carbon content in molten ferro-manganese is described in US Patent No. 3,305,352. In the preferred method for producing the aforementioned manganese manganese oxide smoke, the ferro-manganese is drained from the melting furnace, where it is produced, into a treatment vessel, e.g. a ladle or oven with a temperature of approx. 1300°C or more.

All slag is preferably skimmed off and afterwards oxygen is top blown towards the surface of the molten ferro-manganese bath by any conventional means, e.g. one or more conventional oxygen blowing lances held approx. 2.5 cm above the surface to direct one or more oxygen jets with a pressure of approx. 7.7 to approx. 10.5 kg/cm2 ten to bump against bath over-

the surface. The oxygen flow is approx. 1.8 to 2.3 kg per minute for a melt pool of 227 kg in a ladle with a height of approx. 76 cm and an inner diameter of 50 cm. The above-mentioned method can, if desired, be worked up to a larger scale. The waste gas produced here contains very finely divided particles of manganese-manganese oxide smoke with a spherical configuration. These particles are easily removed from the exhaust gas by conventional extraction equipment ■

If desired, the aforementioned manganese manganese oxide smoke can be produced as a by-product by the special method described in US Patent No. 3,305,352 for reducing the carbon content in the ferro-manganese bath. In such a case, the ferro-manganese bath will have a temperature of approx. 1250°C and oxygen will be top blown at a rate great enough to heat the bath to a temperature of 1700°C before the carbon content of the molten metal is reduced to 1.5% carbon. The oxygen blowout will continue until the temperature in the bath is approx. 1750°C as described in the patent document. The manganese oxide smoke is extracted from the off-gas in a conventional way.

By the terms Mn-jO^-smoke and manganese-manganese oxide smoke which are used in the present description and claims, are meant finely divided spherical particles of smoke obtained from the oxygen blowing out of molten ferro-manganese as described above.

The following data broadly indicate some typical properties of the manganese manganese oxide smoke produced as indicated above for use in the production of the present invention.

Chemical formula: Essentially Mn^O^. Typically 90-95% by weight manganese manganese oxide, the rest being a mixture comprising calcium oxide, magnesium oxide, potassium oxide and silicon dioxide with less than approx. 1 w e c t ?o free manganese metal.

Chemical analysis (typical weight) : 65.27 Mn, 2.03 Fe, 0.029 Al,

0.28 Si, o.17 C, 0.040 P, 0.045 As, 0.46 Ca, 1.43 Mg, 0.072 K,

0.023 Cr and 0.00 2 Pb.

Room weight: 720-1442 kg/m3.

Moisture: 0.22?^ (1 hour at 107°C).

Particle size; 98% under approx. 10 .u . (99?^ will pass through a 325 mesh Tyler sieve).

j2±Ll 9"13 (50?in Mn^O^in distilled water).

Shape: spherical shape.

Specific gravity: 4.6 to 4.75 g/cm3.

Thermal stability: No effect up to 600°C.

Today's coating technology emphasizes the use of color pigments with a very fine particle size re1se to increase color efficiency (staining and covering ability), suspending properties and uniform distribution of the pigment over the entire paint. It has been found that when the Mn-jO^ smoke is used as a color pigment in accordance with the present invention it should have a particle size of less than approx. 10 yt. Typically, Mn.j0^ smoke as described above can contain approx. 1 - 2.0 ?□ particles with a size greater than approx. 10 yrs. Accordingly, it may be desirable or in some cases necessary to eliminate these large diameter particles from the Mn^Oq smoke. This can be done e.g. by a conventional classification technique or by impact methods such as treatment in a ball mill. Manganomonium-ganium oxide smoke which is classified or ground to a particle size where 93.5% of the particles are smaller than approx. 10 jj can be easily dispersed in the paint with a medium displacement equipment, such as using Cowles Dissolver. Paints containing Mn^O^ fumes within this particle size range can generally be applied to the surface to be treated without any signs of streaking or other defects.

A typical particle size measurement for the Mn^O^ fumes is shown in the drawing. It will be seen from the curve in the particular case that for the classified Mn^O^ smoke, which has been determined, the mean particle size distribution is approx. 0.68 jj .

Typical water mu 1 s j on sm a 1 i nges containing Mn^Oty - r ey k-color pigment consistent with the invention are represented by the following:

Water emulsion paints, in which, according to the invention, manganese manganese oxide smoke color pigment is used, can be produced by conventional methods which are well known in the art. E.g. the paints can be produced by first dispersing additives such as dispersing agents, thickeners, protective colloids, antifoam agents, surfactants, etc. in water. The color pigment together with a stretching agent is then dispersed in the water solution using suitable equipment that provides a displacement force such as a Cowles Dissolver or Pebble Mill. The fine solid particles of the pigment and stretching agents are brought into uniform suspension. This prepared pigmented water solution is then mixed with latex, together with liquid agent and the remaining components. The physical properties and characteristics of the paint are tested and the water retention, pH, viscosity and pigment dispersant are adjusted as required. Other methods and equipment can of course be used with equal success, which is easy to see for those skilled in the art.

The latex or emulsion binder used in the paint according to the invention can be any of the well-known latex film formers of acrylic type or acrylic copolymer type which are conventionally used within the paint industry. The latexes "Rhoplex"® AC 507, "Rhoplex" MV9 and "Rhoplex" MV23 manufactured by Rohm and Haas Co., and the latexes "UCAR" R 336, "UCAR" 515, "UCAR" 4341 and "UCAR" 4358 manufactured by Union Carbide Corp. are typical emulsions among many of those commercially available today that are applicable in the practice of the present invention. Thickening agents and protective colloids are used in the paint to achieve the desired consistency and viscosity. The consistency and viscosity should be such that the paint is able to be easily applied to the surface to be treated in an even film of the desired thickness. These additives also act as protective colloids that prevent coagulation of pigments and stretching agents in the presence of electrolytes or under particularly large displacement forces. Thickeners together with surfactants maintain the pigments in suspension and stabilize the viscosity of the paint. The choice of the particular thickener will depend on a number of factors such as e.g. the type of emulsion and plomentVolume concentration and the coating rheology.

In general, thickeners, cellulose type or salts of polyacrylic acids, which are conventionally used within the paint industry can be used in water emulsion paints containing Mn^O^ smoke. Suitable thickeners include e.g. saline polycarboxylic acid such as "Acrysol" (r) G-110 (Rohm and Haas Co.) or cellulose-type thickeners such as "QP 4400" (Union Carbide Corp.). Other thickeners include those sold under the trade names "Thickener" (g) 845, "Thickener" 4358 and "Thickener" E845 (Rohm and Haas Co.).

A combined dispersing-stabilising agent can also be used in the paint to ensure that the entire amount of pigment and the amount of other ingredients are evenly dispersed over the paint. Various anionic, nonionic and polymer-type dispersants can be used for this purpose, such as those manufactured under the trade name "Tamol" ©731 and "Tamol" 850 (Rohm and Haas Co.) Other dispersants that can be used are "Triton" (R) X-100 (alkylary1 phenoxypolyethoxyethanol), "Triton" X-301 (alkylaryl ether sulfate), and "Triton" X-405 (alkylaryl polyether alcohol), all supplied by Rohm and Haas Co.

The paints according to the present invention can also include various other ingredients which are conventionally used within the paint industry. E.g. an antifoam agent such as "Nopco" @ NDW supplied by Nopco Chemical Company can also be used. Conventional drying agents can also be used in cases where the paint contains an alkyd resin as an ingredient. Such drying agents include e.g. cobalt and zirconium desiccants. It is also possible to use a co-flowing agent such as 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate which is supplied by Eastman Kodak under the trademark "Texanol"®. Other known ingredients such as antioxidants, preservatives, antifreeze agents (e.g. ethylene glycol) and modifiers can also be used in the paint, which will be completely clear to the expert.

It has been shown in certain experiments that Mn^Oy smoke can be combined with conventional pigments such as titanium dioxide (TiO ) to produce different color shades.

In such an attempt, e.g. Mn^O^ smoke mixed together with different amounts of Ti0 2°9 the different shades of color produced by this method were recorded. In the same experiments, control samples containing 10 0% Mn xO^ smoke and 100% TiO^ were also prepared for comparison. It was found that the emulsion film in the case of 100% TiO^ (0% Mn^O^) was "basic white", 10% Mn30^ smoke (90% TiO^.) was "light brown" or "beige colored", 40 % Mn 0 smoke (60% TiO^) was "medium brown" and 100% Mn^O^ smoke (0% TiO^) was "dark brown" or "dark reddish-brown".

The color of the emulsion film In the experiment described above can be specified in accordance with the Munsell Book of Color, Munsell Color Company, Baltimore, Maryland, "hue", "value" and "Chroma" determined for each emulsion film in accordance with the methods that are indicated in the Munsell Color Book and is given in Table 1 below. In the column marked "Munsell no." shows the first numerical value and the letter "hue", the number after the letter shows "value" and the last number shows "Chroma". On the basis of the indicated Munsell numbers in table 1, it is easy to see that the manganese manganese oxide smoke dye according to the invention will have a coloring and modifying effect on other pigments such as TiO^, which give certain shades such as yellow iron oxide, Hansa yellow, chrome oxide green , phthalocyanine blue and phthalocyanine green.

The following examples will further illustrate the practice of the present invention.

Example 1

A water emulsion paint was prepared using a standard white titanium dioxide pigment of ruti 1 quality intended for general purposes. The paint composition was first prepared by mixing 60.0 g of rutile titanium dioxide, 70.0 g (pH 9.7) of thickener, i.e. 20% aqueous solution of "Thickener" 745 (Rohm and Hass Co.), 2.0 g dispersant/stabilizer, i.e. "Tamol" 850 (Rohm and Haas Co.), 10.0 g alkylarylphenoxypolyethoxyethanol, i.e. "Triton" 100 (Rohm and Haas Co.), 1.5 g antifoam, i.e. ( Hevi-Duty A.F. Agent" (g)(Interstab Chemicals Inc.), 2.0 g Polypropylene Glycol, 20.0 g Coagulating Agent, i.e. "Butyl Carbitol" ® (Union Carbide Corp.), 2.0 g 28% ammonium hydroxide and 87.5 g of water.After complete mixing, 622 g of latex, i.e. "UCAR" 4358 (Union Carbide Corp.), was added to the mixture.

The above prepared paint was spread on the surface of

several test plates made of bare aluminum of approx. 7.6x23 cm with a drawbar to a thickness of approx. 0.025 mm. The coated test panels were then allowed to cure for approx. 1 week at room temperature and then subjected to a laboratory scale fading test using ultraviolet light. In the test, the coated plates were placed on a test stand and exposed continuously to a constant beam of ultraviolet light conforming to the ASTM G 25-70 Fadometer test. The sample plates were observed periodically for color stability and fading for periods of up to 1000 hours. A fading scale was determined for measuring the degree of fading on the sample plates in the following way:

The results from the fading samples are given in table 2. Each assessment value given in the table is marked "F" to show that the sample is a fading sample, except for the present example where the color pigment was the TiO^.Ti<O>^ pigment mostly gives a "white" pigmentation which will fade with prolonged exposure to ultraviolet light. Thus, in Table 2, the abbreviation "Bl" is used to describe the bleaching of the paint according to this example.

Example 2

A water emulsion paint was prepared using the same ingredients as those used for the paint according to Example 1, except that the 60.0 g of TiO 2 was in this case replaced by 57.0 g of leached Mr 2 O 2 smoke. The Mn^O^ smoke was washed out by exposing the smoke to sodium chloride. In this example, 73.0 g of polycarboxylic acid thickener, i.e. "Thickener" 485 (Rohm and Haas Co.) was added together with 480.0 g of latex, i.e. "UCAR" 4358 (Union Carbide Corp.) instead of the 622.0 g. The paint was spread on test plates in the same way as described in example 1 and subjected to the same fading tests. The film's color was "dark brown" or "dark reddish brown".

Example 3

An emulsion type paint was prepared by dispersing extenders and pigments in an emulsion prepared by mixing long oil alkyd, i.e. "Aroplaz" (r) 1271 (Spencer Kellog Co.) containing cobalt and zirconium drying agents, with water. To 350 g of the alkyd emulsion was added 4.0 g of cellulose thickener, i.e. "QP 4400" (Union Carbide Corp.), 8.0 g of anionic dispersant, i.e. "Tamol" 850 (Rohm and Haas Co.), 5.0 g nonionic surfactant, i.e. "Triton" CF-10 (Rohm and Haas Co.) an alkyl aryl ether type, 50.0 g of an antifoam agent,

i.e. "Hevi-Duty A.F. Agent", and 20.0 g of ethylene glycol. To this prepared binder was added 150.0 g synthetic red iron oxide, 35.0 g stretching agent pigment, i.e. "Mica" © 325 1 evert of the English Mica Company, 75.0 CaCo , 50.0 g rust inhibiting pigment, modified bare iummetagobor at, ie "Busan" © 11-M-1 (Buckman Labs, Inc.) and which was dispersed using a Cowles Dissolver. After complete mixing, 500 g of styrene-acrylic copolymer latex, i.e. "UCAR" 4341 (Union Carbide Corp.) was added

and together liquid.

As in the previous examples, this paint was spread on bare aluminum test plates of approx. 7.6x23 cm with a wire-cover wet film applicator (Meyers) so that a dry film thickness of 0.025 mm was obtained. The applied film or coating was then allowed to cure at room temperature. The test plates were then placed in test stands and subjected to the same fading tests.

Example 4

An emulsion-type paint was prepared by mixing an acrylic resin emulsion, mist. "Rhoplex" (§) MV 23 (Rohm & Haas Co.) together with Mn^Oq fume. The composition was as follows: 5 9 g uann, 25.0 g 20 Vs polyacrylate thickener, dus. "Thickener" E845 (Rohm and Haas Co.), 17.6 g 40 Vs dispersant, doz. "QR-681"

40% (Rohm and Haas Co.), 2.0 g benzyl ether au octylphenol ethylene oxide adduct surfactant, dos. "Triton" CF-10 (Rohm and Haas Co.), 28.0 g ethylene glycol, 5.7 g antifoam, dos. "Foamaster" ® NDW (Diamond Shamrock Co.), 53.0 g CaCo , 2.1 g "Skåne" ® M-8 (Rohm and Haas Co.) which is (2-n-octy1-4-isot iazoline - 3-one )-biocide, and 151 g of Mn^O^-smoke. After complete mixing, 667.0 g of acrylic acid was added. "Rhoplex" MV 23 (Rohm and Haas Co.), 7.0 g ammonium hydroxide (28V; and 5.7 g coagulant, 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, dos. "Texanol " (Eastman Kodak Co.). Test plates (aluminum) were coated with this paint in the same manner as described in the previous examples and the coating was allowed to cure at room temperature. The color of the film was again "dark brown" or "dark reddish brown". It there was no difference in color between the leached and non-leached Mn^O^ fumes.The sample plates were then tested for the same fade samples.

The results of the fading tests using the different paints described in Examples 1-4 are set out in Table 2 below. It will be seen from the results for the fading tests given in table 2 that water emulsion paints containing Mn-^O^ smoke pigments in accordance with the invention provide a color stability and fading resistance which is the same as or better than for paints containing conventional previously known pigments. It will thus be particularly mentioned that the paints according to examples 2 and 4, which contain Mnz,0^ smoke as a color pigment, only showed a small degree of fading, while on the other hand the paint used in ex. 3 using red oxide pigment showed a significantly greater degree of fading (ie from F-10 at 50 hours to F-3 at 1000 hours) As a further comparison, it will be seen from the results in Table 2 that paints produced by using conventional titanium dioxide (Ti0.j_) as a "white" pigment showed signs of bleaching (ex. 1) after only 50 hours of exposure to ultraviolet light. It vU-?

Furthermore, it can be seen from the results in Table 2 that the MnjO^ smoke pigment can be used within a wide variety of paint formulations using different ingredients such as thickeners, dispersants, stabilizers, antifoam agents, preservatives, etc. without any detrimental effect on it on - led the coating. It can be further mentioned from the sample that paints in which leached Mn^O^ smoke is used as a color pigment were not as stable as paints using non-leached Mn^O^ smoke. However, the leached Mn^O^ fume when used as a dye showed better light fastness properties compared to synthetic red iron oxide.

Claims (5)

1. V/an emu 1 sion sma l i ng mainly containing acrylic resin emulsion, thickener, dispersant and color pigment, with improved color stability and resistance to fading, characterized in that the paint has added a color pigment comprising finely divided manganese manganese oxide smoke particles. 2. Water emulsion paint according to claim 1, characterized in that the manganese oxide color pigment is Mn^Oq smoke with the following properties: a) a chemical composition containing at least approx. 90% manganese manganese oxide, the rest being a mixture comprising calcium oxide, magnesium oxide, potassium oxide and silicon oxide with less than approx. 1 wt% free manganese metal, and b) a particle size where 98% is less than approx. 10 right. 3. Water emulsion paint according to claim 1, characterized in that it comprises from approx. 40 to 65% latex preparation, from approx. 0.5 to approx. 12% by weight thickener, from approx. 0.2 to 2.0 % dispersing agent, from approx. 0.2 to 2.0 % surfactant, from approx. 0.1 to 1.0 wt% antifoam, from approx. 0.3 to 6.0 wt.% of coagulant, from approx. 0.1 to 1.5 wt % preservative, from approx. 0.0 to 15.0% by weight extender, from approx. 5.0 to 30 wt% Mn^Ou fume, from approx. 0.0 to 25 \/ ect% TiO^, and the rest water, 4. Water emulsion paint according to claim 3, characterized in that it further contains from 0 to approx. 8.0 \ iect% antifreeze. 5. Water emulsion paint according to claim 3, characterized in that it further contains from 0 to approx. 10.0 wt % alkyd resin.