GB2113664A - Water emulsion paint compositions - Google Patents

Abstract

Manganomanganic oxide fume or a material containing manganomanganic oxide fume is used as a colorant with good staining and retention properties in compositions of water emulsion based coatings.

Description

SPECIFICATION Water emulsion paint compositions and pigment materials therefor The present invention relates generally to paints using water emulsion vehicles. More specifically, the invention relates to water emulsion paint compositions containing a novel colorant with improved properties for enhancing the colour stability of these paints.

Conventional water emulsion paint compositions are prepared by dispersing one or more colour pigments in water containing suitable additives such as surfactants, stabilizers, dispersing agents and thickeners, followed by mixing with film formers, for example, latex, acrylic, acrylic copolymers and acrylic containing emulsions. An essential requirement of any pigment is first that it must produce a distinctive and pleasant colour when added to the paint composition either alone or together with other pigments. Additionally, the pigment must be stable so as to retain its colour for a prolonged period of time. Another important requirement is that the pigment should have a very finely-divided particle size generally less than about ten microns.The fineness of the particles enhances the ability of the pigment to be easily dispersed throughout the paint mixture during processing and further assures that the paint will be evenly distributed in a thin layer upon application to a surface without any streaks or other imperfections. This latter requirement is most significant of course in those instances where the paint is to be applied by conventional brush, roller or spray techniques.

It is therefore an important object of the present invention to provide an improved pigement for use in water emulsion paint compositions. Another more specific object of the present invention is to provide an improved water emulsion paint composition having good colour stability and a relatively high resistance to fading upon exposure to sunlight.

In accordance with one aspect of the present invention, there is provided a water emulsion paint composition comprising a colour pigment material which comprises manganomanganic oxide fume. In accordance with another aspect of the invention a colour pigment material for a water emulsion paint composition comprises manganomanganic oxide fume. In accordance with a third aspect of the invention manganomanganic oxide fume is provided for use as, or as an ingredient of, a colour pigment material in a water emulsion paint composition. The improved colour pigments for use in water emulsion paint compositions preferably comprise manganomanganic oxide (Mn304) fume or a material containing manganomanganic oxide fume as their principle ingredient.The Mn304 fume colorant may first be dispersed in water containing surfactants, dispersing agents, defoamers, extenders, thickeners, stabilizers, glycols and the like and then introduced into a water emulsion based on latex type acrylics or acrylic copolymers. The Mn304 fume colorant may comprise from about 5 to 50% by weight of the total non-volatile portion of the paint composition.

The present invention will be described in greater detail with reference to the accompanying drawing which is a graph showing the particle size distribution for a preferred manganomangic oxide fume containing material for use as a colour pigment in accordance with the invention.

The present invention is based upon the discovery that manganomanganic oxide fume or a material containing predominantly manganomanganic oxide fume, preferably in a finely-divided state is anovel and useful colorant for use in formulating a variety of water emulsion paints. In particular, the My304 fume colour pigment material is especially useful in those applications where conventional iron oxide pigments have heretofore been employed in the preparation of coloured water emulsion paints. It has been found, for example, that finely-divided manganomanganic oxide fume when ised as, or as an ingredient of, a colour pigment exhibits a dark brown or deep reddish-brown colour which is similar to but yet quite readily distinguishable from the brown colour pigmentation produced by a number of synthetic iron oxide pigments, eg, yellow, tan or red iron oxide pigments.It has also been found that Mn2O4fume colour pigment material is stable at high temperatures up to about 600"C while, on the other hand, conventional yellow or tan iron oxide pigments revert to red iron oxide when heated to temperatures of about 350"C. The Mn304 fume colour pigment material also can be produced in a wide range of particle sizes which approach or equal the particle size of convention iron oxide pigments of the prior art. As indicated, it is desirable that the colour pigment material should possess a very finely divided particle size in order to enable the pigment material to be uniformly distributed throughout the entire paint composition during its formulation. Generally, the manganomanganic oxide fume pigment material should have a particle size of below about 10 microns.

As indicated, the colour pigment material used in the practice of the present invention is manganomanganic oxide fume or may be a composition or material containing predominantly manganomanganic oxide fume ie, greater than about 60% by weight.

The Mn3O4 fume of the present invention is most conveniently prepared by passing a stream of oxygen through or across the surface of a molten bath of ferro-manganese. Conventional ferro-manganese produced in a blast furnace or in an electro-metallurgical furnace and the like at high temperatures of about 1 2000C or more may contain up to 6 or more percent of carbon. The carbon content is usually reduced, as for example, to about 1.5% by blowing oxygen or a mixture of oxygen and air through or against the surface of a bath of molten ferro-manganese. This is done in a separate vessel that contains a molten ferro-manganese bath freshly tapped from the electric furnace and at a temperature of about 1000"C or more and preferably at about 1300"C or more.

One procedure for reducing the carbon content of molten ferro-manganese is described in US Patent No.

3,305,352, the description of which is incorporated by reference herein. In this preferred procedure for producing the manganomanganic oxide fume of the present invention, ferro-manganese is tapped from the electric furnace in which it is produced into a treating vessel such as a ladle or furnace at a temperature of about 1300"C or more. Any slag is preferably skimmed off and then oxygen is top blown against the surface of the molten ferro-manganese bath by any convenient means such as one or more conventional oxygen blowing lances held about an inch above the surface to direct one or more streams of oxygen at a pressure of about 7734 to about 10546g/cm2 (about 110 to about 150 psi) to impinge against the surface of the bath.The flow of oxygen is about 1814 to 2268gm (about 4 to 5 pounds) per minute for a 226800gm (500 pound) molten bath in a ladle about 76cm (30 inches) high and 51cm (20 inches) inside diameter. The foregoing procedure may be scaled up as desired. The off-gas thereby produced contains very finely divided particles of manganomanganic oxide fume of spherical configuration which are easily recovered from the off-gas by conventional recovery apparatus.

If desired, the manganomanganic oxide fume of the present invention may be produced as a by-product of the specific procedure described in US Patent No.3,305,352 for reducing the carbon content of the ferro-manganese bath. In such case, the ferro-manganese bath will be at a temperature of about 12500C and oxygen will be top blown at a rate sufficient to heat the bath to a temperature of 1 7000C before the carbon content of the molten metal has been reduced to 1.5%. Oxygen blowing will continue until the bath temperature reaches about 17500C as described in the patent. The manganomanganic oxide fume is recovered from the off-gas in conventional manner.

The terms Mn304 fume and manganomanganic oxide fume used in the specification and claims herein mean the spherical particles of fume recovered from the oxygen blowing of molten ferro-manganese as described above.

The following data outlines some typical characteristics of manganomanganic oxide fume produced as specified hereinabove for carrying out the present invention: Chemical Formula: Essentially Mn3O4. Typically, 90 to 95% and more by weight manganomanganic oxide, the balance being a mixture which includes calcium oxide, magnesium oxide, potassium oxide and silica with less than about 1% by weight of free manganese metal.

ChemicalAnalysis (typical wt%): 65.27Mn; 2.03Fe; 0.029AI; 0.28Si; 0.17C; 0.040P; 0.045As; 0.46Ca; 1.43Mg; 0.072K; 0.023Cr; and 0.002Pb.

Bulk Density: 720 - 1442kg/m3 (45 - 901bs/ft3).

Moisture: TypicallyO.22%(1 hour at 107%).

Particle Size: 98% below 10 microns (99% will pass through a 325 Tyler screen).

ph: 9-13 (50% Mn3O4 in distilled H2O).

Shape: spherical.

Specific Gravity: 4.6 to 4.75 grams/cc Thermal Stability: No effect up to 600"C.

Present day coating technology stresses the use of colour pigment materials having a very fine particle size in order to enhance colorant efficiency (staining and hiding power), suspension properties and uniform distribution of the pigment throughout the body of the paint formulation. It has been found that when used as a colour pigment in accordance with the present invention, the Mn304 fume should have a particle size of below about 10 microns. Typically, MN304 fume as described above may contain from about 1 to 2.0% particles of a of a size greater than about 10 microns. Accordingly, it may be desirable or even necessary in some cases to eliminate these large diameter particles from the Mn304fume. This may be done, for example, by conventional classification techniques or by impact methods such as ball milling.Mangano manganic oxide fume which has been classified or milled to a particle size wherein 99.5% is less than about 10 microns can be readily dispersed in the paint formulation with medium shear equipment such as by use of a Cowles dissolver. Paint compositions containing Mn304 fume in this particle size range can generally be applied to the surface to be treated without any evidence of streaking or other imperfections.

A typical particle size distribution curve for My304 fume is shown in the graph of the drawing. It will be seen from the curve that in the particular case of the classified Mn304 fume evaluated, the medium particle size distribution is about 0.68 microns.

Typical water emulsion paint compositions containing Mn304 fume colour pigment in accordance with the present invention are represented by the following: Amount Ingredients % by weight Latex 40 -65 Thickener 0.5 - 12 Dispersant/Stabilizer 0.2 - 2.0 Surfactant 0.2 - 2.0 Defoamer 0.1-1.0 Coalescing Agent 0.3 - 6.0 Preservative 0.1 - 1.5 Extender 0.0-15.0 Mn3O4fume 5.0-30 TiO2 0.0 - 25.0 Freeze Preventative 0.0 - 8.0 Alkyd Resin or Vegetable Oil 0.0 - 10.0 Water Balance The water emulsion paint compositions employing a manganomanganic oxide fume colour pigment material in accordance with the present invention can be made by appropriate conventional methods that are well known in the prior art.For example, the paint compositions can be prepared by first dispersing in water additives such as dispersant(s), thickening agent(s), protective colloid(s), defoamer(s) and surfactant(s). The colour pigment together with an extender is then dispersed through the water solution using suitable shear equipment such as a Cowles Dissolver or Pebble Mill. The fine solid particles of pigment and extenders are brought into uniform suspension. The pigmented water solution thus obtained is then blended with latex, coalescing agent and the remaining components. Physical properties and characteristics of the paint are checked and surface tension, pH, viscosity, and pigment dispersment are adjusted as necessary.

other methods and equipment may, of course, be employed with equal success as will readily occur to those skilled in the art.

The latex or emulsion vehicle used in the paint composition according to the present invention may be any one of the well known acrylic or acrylic copolymer type latex film formers conventionally employed in the paint industry. Rhoplex AC 507, Rhoples MV9 and Rhoplex MV23 latexes produced by Rohm and Haas Co and UCAR 336, UCAR 515, UCAR 4341 and UCAR 4358 latexes produced by Union Carbide Corporation are typical emulsions among many commercially available today which are useful in the practice of the present invention.

Thickeners and protective colloids are used in the paint composition in order 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 a uniform film of desired thickness. Those additives also function as protective colloids that guard against coagulation of pigments and extenders in the presence of electrolytes or excessive shears. Thickening agents jointly with surfactants, maintain pigments in suspension and stabilize the viscosity of the paint. The choice of a particular thickening agent will depend on a number of factors such as, for example, the type of emulsion and pigment volume concentration and coating rheology.

Generally, thickening agents, cellulosic type or salts of polyacrylic acids, conventionally used in the paint industry may be employed in the water emulsion paint compositions containing Mn304 fume. Suitable thickeners include, for example, salts of polycarboxylic acid such as Acrysol G-110 (trademark of Rohm & BR< Haas Co) or cellulosic type thickeners such as OP4400 (trade mark of Union Carbide Corp). Other thickeners include those sold under the trademarks Thickener 845, Thickener 4358 and Thickener E845 (trademarks of Rohm & Haas Co).

A combined dispersion-stabilizer agent may also be used in the paint formulation in order to assure that all of the pigment and other ingredients are uniformly dispersed throughout the paint. Various anionic, non-ionic and polymer type dispersion agents can be employed for this purpose such as those produced under the trademark Tamol 731 and Tamol 850 (Rohm and Haas Co). Other dispersants that may be employed are Triton X-100 (alkylaryl phenoxy polyethoxy ethanol), Triton X-301 (alkylaryl ether sulphate) and Triton X-405 (allylaryl polyether alcohol) all trademarks of Rohm and Haas Co.

The paint formulations of the present invention may also include various other ingedients that are conventionally employed in paint industry. For example, a defoamer such as Nopco NDW made by Nopco Chemical Company may also be used. Conventional driers ay also be employed in those instances where the paint formulation contains an alkyd resin as an ingredient. Such driers include for example cobalt and zirconium driers. A coalescing agent may also be used as 2,2,4 trimethyi 1,3 pentanediols monoisobutyrate produced by Eastman Kodak under the trade Texanol. Other known ingredients such as antioxidants, preservatives, freeze preventatives (eg, ethylene glycol) and modifiers may also be used in the paint formulations as will readly occur to those skilled in the art.

It has been found in certain experiments that Mn304 fume can be combined with conventional pigments such as titanium dioxide (TiO2) to produce various shades of colour. For example, in one such experiment, Mn3O4 fume was blended together with different amounts of TiO2 and the different shades of colour so produced were recorded. In the same experiments, control samples containing 100% Mn304 fume and TiO2 respectively were also made for comparison.It was found that the emulsion film in the case of 100% TiO2 (0%Mn304) was "basic white", 10% Mn3O4 fume (90%it02) was "light brown" or "beige", 40% Mn3O4 fume (60%TiO2) was "medium brown" and 100% Mn304fume (0%TiO2) was "dark brown" or "deep reddish brown".

The colour of the emulsion film in the above described experiment can be specified according to the Munsell Book of Color, Munsell Color Company, Baltimore, Maryland. The hue, value and Chroma were determined for each emulsion film in accordance with the procedures outlined in the Munsell Colour Book and are given in Table I below. In the column labelled "Munsell No.", the first numerical value and letter designation represent the "hue", the number following the letter designation represents the "value" and the last number represents the "Chroma".

TABLE 1 Colour definition % TiO2 % Mn304Fume Munsell No.

100 0 N 9.5/ 90 10 5YR 8/2 60 40 7.5YR 5/2 0 100 5YR 3/4 Based on quoted Munsel No. in Table I, it will be readily seen that the manganomanganic oxide fume colorant of the present invention will have a staining and modifying effect on other pigments such as TiO2, which produce definite shades such as yellow iron oxide, Hansa yellow, chrome oxide green, phthalocy anine blue, and phthalocyanine green.

The following examples will further illustrate the practice of the present invention: Example 1 Awater emulsion paint composition was prepared using a standard general purpose rutile grade titanium dioxide white pigment. The composition was prepared first by blending together 60.0 grams of rutile titanium dioxide; 70.0 grams of (pH 9.7) thickener, ie, 20% water solution Thickener 745 (Rohm and Haas Co); 2.0 grams of a dispersant/stabiliser, ie, Tamol 850 (Rohm and Haas Co); 10.0 grams of alkylaryl phenoxy polyethoxy ethanol, ie, Triton 100 (Rohm and Haas Co); 1.5 grams of defoamer, ie, Hevi-Duty AF Agent (Interstab Chemicals Inc); 2.0 grams polypropylene glycol; 20.0 grams of a coalescent, ie, Butyl Carbitol (Union Carbide Corp); 2.0 grams ammonium hydroxide 28%, and 87.5 grams of water.After thorough mixing, 622 grams of latex, ie, UCAE 4358 (Union Carbide Corp) were added to the blend.

The paint composition so prepared was spread onto the surface of several test panels made of bare aluminum measuring approximately 7.6cm x 22.9cm (3 x 9 inches) with a drawbar to a thickness of about 0.00254cm (1 mil). The coated test panels were then allowed to cure for approximately one week at room temperature and were then subjected to fade test on a laboratory scale using ultraviolet light. In the test, the coated panels were placed on test racks and continuously exposed to a constant source of ultraviolet light in accordance with ASTM G 25-70 Fadometer Test. The test panels were periodically observed for colour stability and fading over periods of up to 1,000 hours.A rating code was established for measuring the degree of fading of the test panels as follows: Rating Code 10 - No change 9 - Very slight change 8 - Slight change 7 - Medium + 6 - Medium 5 - Medium 4 - Slight bad 3 - Bad 2 - Very bad 1 - Partial Failure 0 - Failure The results of the fade tests are given in Table II. Each rating code given in the table is preceded by the letter "F" to indicate that the test is a fade test, except in the present example where the colour pigment was TiO2. TiO2 pigment produces essentially "white" pigmentation which upon prolonged exposure to ultraviolet light will bleach. Thus, in Table II, the abbreviation "Blch" is employed to denote bleaching of the paint formulation in this example.

Example 2 A water emulsion paint composition was prepared using the same ingredients as those employed in the paint composition of Example 1, except that in this case the 60.0 grams of TiO2 were replaced by 57.0 grams of leached Mn304 fume. The Mn3O4 fume was leached by subjecting the fume to hydrochloric acid. Also, in this example, 73.0 grams of polycarboxylic acid thickener, ie, Thickener 485 (Rohm and Haas Co) were employed along with 480.0 grams of latex ie, UCAR 4358 (Union Carbide Corp) instead of the 622.0 grams which were added. The paint composition was spread onto test panels in the same manner described in Example 1 and subjected to the same fade tests. The colour of the film was "dark brown" or "deep reddish brown".

Example 3 An emulsion type paint composition was prepared by dispersing extenders and pigments in an emulsion prepared by blending long oil alkyd ie, Aroplaz 1271 (Spencer Kellog Co) containing cobalt and zirconium driers, with water. To 350 grams of the alkyd emulsion was added 4.0 grams of cellulosic thickener ie, QP 4400 (Union Carbide Corp); 8.0 grams of anionic dispersion agent ie, Tamol 850 (Rohm and Haas Co); 5.0 grams of nonionic surfactant ie, Triton CF-10 (Rohm and Haas Co) an alkyl-aryl-ethertype; 5.0 grams of a defoamer ie, Hevi-Duty A F Agent; 20.0 grams of ethylene glycol.Into the thus obtained vehicle, 150.0 grams of synthetic red iron oxide, 35.0 grams of extender pigment ie, Mica 325 sold by English Mica Company; 75.0 grams of CaCO3; 50.0 grams of rust inhibitive pigment, modified barium metaborate; ie, Busan 11-M-1 (trademark of Buckman Labs, Inc) was introduced and dispersed using a Cowles Dissolver. After thorough mixing, 500 grams of styrene-acrylic copolymer latex, ie, UCAR 4341 trademark of Union Carbide Corp) and coalescing agent were added.

As in the previous examples, this paint formulation was spread onto bare aluminum test panels measuring approximately 7.6 x 22.9 cm (3 x 9 inches) with a wire wrap wet film aplicator bar (Meyers) to give a dry film thickness 0.00254cm (1 mail). The applied film or coating was then allowed to cure at room temperature. The test panels were then placed on test racks and subjected to the same fade tests.

Example 4 An emulsion type paint composition was prepared by blending an acrylic emulsion ie, Rhoplex MV23 (Rohm & Haas) Co together with M N304 fume. The composition was as follows: 59 grams of water; 25.0 grams of 20% concentration polyacrylate thickener, ie, Thickener E845 (Rohm and Haas Co); 17.6 grams 40% concentration dispersant ie, QR-681 40% (Rohm and Haas Co); 2.0 grams of benzylether of octylphenolethylene oxide aduct surfactant, ie, Triton CF-10 (Rohm and Haas Co); 28.0 grams ethylene glycol; 5.7 grams of defoamer, ie, Foamaster NDW (Diamond Shamrock Co); 12.0 grams of zinc oxide pigment, ie, AZO 77 (American Zinc Co); 53.0 grams CaCO3; 2.1 grams Skane M-8 (Rohm and Haas Co), which is 2-n-octyl-4-isothiazolin-3-one) biocide; and 151 grams Mn304 fume.After thorough mixing, 667.0 grams of acrylic latex, ie, Rhoplex MV 23 (Rohm and Haas Co), 7.0 grams of ammonium hydroxide (28%) and 5.7 grams coalescing agent, 2,2,4 Trimethyl 1,3 pentane-diol-monisobutyrate, ie, Taxanol (Eastman Kodak Co) were added to the blend. Test panels (aluminum) were coated with this paint formulation in the same manner as described in the previous examples and the coating allowed to cure at room temperature. The colour of the film was again "dark brown" or "deep reddish brown". There was basically no difference in colour between the leached and unleached Mn3O4 fume. The test panels were then subjected to the same fade tests.

The results of the fade tests using the various paint compositions described in Examples 1 to 4 are reported in Table II below.

TABLE II Fade test Time (hers.) Example Pigment 50 100 200 300 400 500 600 750 1000 1 TiO2 Blch Blch Blch Blch Blch Blch Blch Blch Blch 2 Mn3O4fume F-8 F-7 F-6 F-6 F-6 F-5 F-5 F-5 F-5 Leached 3 Red Oxide F-10 F-9 F-9 F-9 F-8 F-3 F-3 F-3 F-3 4 Mn304fume F-10 F-9 F-8 F-8 F-8 F-8 F-8 F-8 F-7 It will be seen from the rsults of the fade test reported in Table II that water emulsion paint compositions containing Mn304 fume pigments in accordance with the present invention exhibit colour stability and fade resistance which is equal or superior to that of paint compositions containing conventional pigments of the prior art. Thus it will be noted in particularthatthe paint compositions in Examples 2 and 4, containing Mn304fume as a colour pigment material demonstrated only a slight degree of fading while on the other hand, the paint composition employed in Example 3 using red oxide pigment evidenced a much 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 of Table II that paint compositions prepared using conventional titanium dioxide (TiO2) as a "white" pigment showed evidence of bleaching (Example 1) after only 50 hours exposure to ultra violet light.

It will be further evident from the results of Table II that the M n304 fume pigment can be employed in a wide variety of paint formulations using varius ingredients such as thickeners, dispersants, stabilizers, defoamers and preservatives without any adverse effect on the applied coating. It may be further noted from the test that paint formulations using leached M n304 fu me as the colour pigment material were not as stable as paint formulations using unleached Mn3O4 fume. However, the leached M n304 fu me when used as a colorant, presented more fade resisting properties compared with synthetic red iron oxide.

Claims (13)

1. A water emulsion paint composition comprising a colour pigment material which comprises manganomanganic oxide fume.

2. A paint composition as claimed in Claim 1 comprising latex acrylic emulsion vehicle, thickener, and dispersant.

3. A paint formulation as claimed in Claim 1 or Claim 2 wherein the manganomanganic oxide fume has the following characteristics: (a) a chemical composition containing at least 90% by weight manganomanganic oxide, the balance being a mixture including calcium oxide, magnesium oxide, potassium oxide and silica with less than 1% by weight of free manganese metal, and (b) a particle size wherein 98% is less than 10 microns.

4. A paint composition as claimed in any of Claims 1 to 3 comprising: from 40 to 65% by weight of a latex vehicle; from 0.5 to 12% by weight of thickener; from 0.2 to 2.0% by weight of dispersant; from 0.2 to 2.0% by weight of surfactant; from 0.1 to 1.0% by weight of defoamer; from 0.3 to 6.0% by weight of coalescing agent; from 0.1 to 1.5% by weight of preservative; from 0.0 to 15.0% by weight of extender; from 5.0 to 30% by weight of the Mn3O4 fume; from 0.0 to 25% by weight of TiO2; the balance being water;

5. A paint formulation as claimed in Claim 4 further including up to 8.0% by weight of freeze preventative.

6. A paint formulation according to claim 4 or claim 5 further including up to 10.0% by weight of an alkyd resin.

7. A water emulsion paint formulation substantially as described herein.

8. A colour pigment material for a water emulsion paint composition comprising manganomanganic oxide fume.

9. A colour pigment material as claimed in Claim 8 further comprising TiO2.

10. A colour pigment material as claimed in Claim 8 or Claim 9 wherein the manganomanganicfume has the following characteristics: (a) a chemical composition containing at least 90% by weight manganomanganic oxide, the balance being a mixture including calcium oxide, magnesium oxide, potassium oxide and silica with less than 1% by weight of free manganese metal, and (b) a particle size wherein 98% is less than 10 microns.

11. A colour pigment material for an emulsion paint composition substantially as described herein.

12. Manganomanganic oxide fume for use as, or as an ingredient of, a colour pigment material in a water emulsion paint composition.

13. Manganomanganic oxide fume as described in Claim 12 having the following characteristics: (a) a chemical composition containing at least 90% by weight manganomanganic oxide, the balance being a mixture including calcium oxide, magnesium oxide, magnesium oxide, potassium oxide and silica with less than 1% by weight of free magnese metal, and (b) a particle size wherein 98% is less than 10 microns.