NL8300068A - PAINT COMPOSITIONS WITH IMPROVED COLOR STABILITY. - Google Patents

Description

* 4 »..

N.0. 31,543 ±

Paint compositions with improved color stability. ^

The present invention generally relates to coatings using water emulsion carriers. More particularly, the invention relates to water-emulsion paint compositions containing a new colorant with improved properties for increasing the color stability of these paints.

Conventional water emulsion paint compositions are prepared by dispersing one or more aqueous color pigments containing suitable additives such as surfactants, stabilizers, dispersants and thickeners, followed by mixing with film-forming agents such as acrylic, acrylic copolymers and acrylic containing emulsions. An essential requirement of any pigment is primarily that it must produce a distinctive and pleasant color when added to the paint composition either alone or together with other pigments. In addition, the pigment should be stable so that its color is maintained for an extended period of time. Another important requirement is that the pigment should have a very finely divided particle size, which is generally less than about 10 microns. The fineness of the particles increases the ability of the pigment to be easily dispersed by the paint mixture during processing and further ensures that the paint will be evenly thinly coated after application to the surface without streaks or other imperfections . The latter requirement is of course most important in those cases where the paint must be applied according to the usual brush, roller or spray techniques.

It is therefore an important object of the present invention to provide an improved pigment for use in water-emulsion paint compositions. Another more specific object of the present invention is to provide an improved water-emulsion paint composition with good color stability and relatively high fade resistance after exposure to sunlight.

According to the present invention, there is provided an improved color pigment for use in water-emulsion paint compositions consisting of smoked manganese (II, III) oxide (M 2 O 3) or a product containing smoked 110 3 0 3 0 3 as the main ingredient. The smoked pigment is first dispersed in water containing surfactants, dispersants, anti-foaming agents, extenders, thickeners, stabilizers, glycols and the like 8300068 ♦ 1 "2 and then fed to a water emulsion based on acrylic polymers or acrylic copolymers. The smoked M 2 O 2 pigment can make up about 5 to 50% by weight of the total non-volatile portion of the paint composition.

The present invention will be described in more detail with reference to the accompanying figure, which is a graphical representation showing the particle size distribution of a smoked product which is preferred for use as a color pigment.

The present invention is based on the finding that smoked MngO4 or a product containing predominantly smoked M113O4 in finely divided state is a new and ideal colorant for use in formulating various raiter emulsion paints. In particular, the smoked MngO 2 color pigment is particularly suitable for those applications where conventional iron oxide pigments have hitherto been used for the preparation of colored water emulsion paints. For example, it has been found that finely divided smoked ΜηβΟ ^ when used as a color pigment exhibits a dark brown or deep reddish brown color, which is similar to, yet fairly easily distinguishable from, the brown color pigmentation induced by a number of synthetic iron oxide pigments, for example yellow, tan or red iron oxide pigments. It has also been found that smoked i-color carbon pigment is stable at high temperatures up to about 600 ° C, while, on the other hand, conventional yellow or tan iron oxide pigments return to red iron oxide upon heating at temperatures of about 180 ° C. The smoked linocolor pigment can also be produced in a wide range of particle sizes that approximate or equal the particle size of the iron oxide pigments of the prior art. As indicated, it is desirable that the color pigment should have a very finely divided particle size in order to distribute the pigment evenly throughout the paint composition during its formulation. Generally, the smoked MngO 2 pigment should have a particle size less than about 10 microns.

As indicated, the color pigment used in the practice of the present invention is smoked M 2 O 2, or may be a composition or product containing predominantly smoked Mr 2 O 2, i.e., greater than about 60% by weight.

The smoked vanηβΟ ^ of the present invention is most conveniently prepared by passing a stream of oxygen through or over the surface of a molten ferro-manganese bath. The conventional ferro-manganese produced in a blast furnace or in an electro-metallurgical furnace and the like at high temperatures of about 1200 ° C or more may contain up to 6 or more percent carbon. The carbon content is usually reduced, such as, for example, to about 1.5% by blowing oxygen or a mixture of oxygen and air through or against the surface of a molten ferro-manganese bath. This is carried out in a separate kettle containing a freshly melted ferrous manganese drawn from the electric oven and at a temperature of about 1000 ° C or more and preferably at about 1300 ° C or more.

One method of reducing the carbon content of molten ferro-manganese is described in U.S. Patent 3,305,352. In this preferred method for the preparation of smoked 15 MngO 2 of the present invention, ferro-manganese is drawn from the electric furnace in which it is produced into a treatment kettle such as a spoon or oven at a temperature of about 1300 ° C or more. Preferably, any slag is skimmed and then oxygen is blown up against the surface of the molten fer-20 manganese bath by any suitable means, such as one or more conventional oxygen blowing lances, which are held approximately one inch above the surface to provide one or more bumping more oxygen streams against the surface of the bath at a pressure of about 720 to 1050 kPa. The oxygen flow is about 18 to 22.5 kg per minute for a 225 kg molten bath in a spoon about 75 cm high and 50 cm internal diameter. The preceding method can be increased in scale if desired. The waste gas generated thereby contains very finely divided particles of smoked M113O4 of spherical configuration, which are easily recovered from the waste gas by conventional extraction equipment. If desired, the smoked β-βαβΟΟ of the present invention can be produced as a by-product of the specific method described in U.S. Pat. No. 3,305,352 for reducing the carbon content of the ferro-manganese bath. In such a case, the ferro-manganese bath 35 will be at a temperature of about 1250 ° C and oxygen will be blown on top at a rate sufficient to heat the bath at a temperature of 1700 ° C before the carbon content of the molten metal decreases is up to 1.5%. Inflation of oxygen will continue until the bath temperature reaches about 1750 ° C, as described in the patent 40. The smoked MngO4 is recovered from the waste gas in the usual manner in 8300068 * 4.

The term smoked Mn-10, as used herein, means the finely divided spherical smoke particles recovered from the oxygen blowing of molten ferro-manganese as described above.

The following data outline some conventional properties of smoked Mi 2 O 2 as prepared as indicated above for the practice of the present invention.

Chemical formula: Mainly Μη30 ^. Usually 90 to 95 wt% and more M 2 O 2, the balance consisting of a mixture containing 10 calcium oxide, magnesium oxide, potassium oxide and silicon oxide with less than about 1 wt% free manganese metal.

Chemical analysis (wt%): 65.27Mh; 2.03Fe; 0.029A1; 0.28Si; 0.17C; 0.040P; 0.045As; 0.46Ca; 1.43Mg; 0.072K; 0.023Cr and 0.002Pb.

Bulk density: 7.2 - 14.4 g / cm ^ 15 Moisture: usually 0.22% (1 hour at 107 ° C)

Particle size: 98% 10 μm (99% will pass through a 325

Tyler sieve) pH: 9-13 (50% Mn30 ^ in distilled H20)

Shape: sphere 20 Density: 4.6 to 4.75 grams / cnr *

Thermal stability: no effect up to 600 ° C

Contemporary coating technology emphasizes the use of very fine particle size color pigments to improve colorant efficiency (coloring and hiding power), slurry properties and even distribution of the pigment by the mass of the paint formulation. It has been found that when used as a color pigment in accordance with the present invention, the smoked Mn304 will have a particle size less than about 10 microns. Typically, as described above, smoked Μη30 ^ may contain from about 1 to 2.0% particles of a size greater than about 10 microns. Accordingly, in some cases it may be desirable or even necessary to remove these large diameter particles from the smoked Mn30. This can be done, for example, according to the usual classification techniques or by collision methods, such as ball milling. Smoked Mn 3 O 3 classified or milled to a particle size where 99.5% is less than about 10 micrometers can be dispersed readily in the paint formulation with medium shear equipment such as using a Cowles dissolver. Paint compositions containing smoked 40 Hn 3 O 3 in this particle size range can generally be applied to the surface to be treated without any evidence of streaks or other imperfections.

A typical particle size distribution curve for smoked is shown in the graph of the accompanying figure. This curve shows that in the particular case of the rated, classified smoked, the average particle size distribution is about 0.68 micrometers.

Conventional water-emulsion paint formulations containing smoked kleurηβ uitvinding ^ color pigments of the present invention are suggested by the following:

Ingredients Amount in wt%

Latex 40-65

Thickener 0.5-12

Dispersant / stabilizer 0.2-2.0 Surface active agents 0.2-2.0

Anti-foaming agent 0.1-1.0

Coalescing agent 0.3-6.0

Preservative 0.1-1.5

Removal agents 0.0-15.0 20 Smoked MU3O4 5.0-30

TiO2 0.0-25.0

Antifreeze 0.0-8.0

Alkyd resin or vegetable oil 0.0-10.0

Water residue The water-emulsion paint compositions using a smoked Ο3Ο4 color pigment of the present invention can be prepared by conventional methods known in the art. For example, the paint formulations can be prepared by first dispersing in water additives such as dispersants, thickeners, protective colloids, anti-foaming agents, surfactants, etc. The color pigment along with a cutting agent is then dispersed through the water solution using suitable shearing equipment, such as a Cowles solution. direction or ball mill. The fine solid particles of pigment and extenders are placed in an even suspension. The pigmented water solution thus obtained is then mixed with latex, coalescing agent and the other ingredients. The physical properties and properties of the paint are controlled and the surface tension, pH, viscosity and pigment dispersion 40 are adjusted if necessary. Other methods and equipment 8300068 6 can of course be used with equal success, as will be apparent to those skilled in the art.

The latex or emulsion support used in the paint composition of the present invention can be any of the known acrylic or acrylic copolymer type latex-film formers commonly used in the paint industry. Rhoplex AC 507, Rhoplex MV9 and Rhoplex MV23 latices from Rohm and Haas co. and UCAR 336, UCAR 515, UCAR 4341 and UCAR 4358 latices from Union Carbide Corp. are conventional emulsions among many commercially available emulsions suitable for the practice of the present invention.

Thickeners and protective colloids are used in the paint composition to achieve the desired consistency and viscosity. The consistency and viscosity should be such that the paint can be easily applied to the surface to be treated in a uniform film of desired thickness. These additives also function as protective colloids, which guard against coagulation of pigments and extenders in the presence of electrolytes or excessive shear forces. Thickeners along with surfactants maintain pigments in suspension and stabilize the viscosity of the paint. The choice of a particular thickener will depend on a number of factors, such as, for example, the type of emulsion and pigment volume concentration and coating rheology.

Generally, cellulose type 25 thickeners or polyacrylic acid salts commonly used in the paint industry can be used in the water-emulsion paint compositions containing smoked ,ηβooktΜ. Suitable thickeners include, for example, salts of polycarboxylic acids such as Acrysol G-1010 (trade name of Rohm and Haas Co.) or thickeners of the cellulose type, such as QP4400 (trade name of Union Carbide Corp.). Other thickeners include those sold under the trade names Thickener 845, Thickener 4358 and Thickener 45845 (trade names of Rohm and Haas Co.).

A combined dispersant stabilizer can also be used in the paint formulation to ensure that the total amount of pigment and other ingredients are evenly dispersed throughout the paint. Various anionic, nonionic polymer-type dispersants and dispersants can be used for this purpose, such as those prepared under the tradenames Tamol 731 40 and Tamol 850 (Rohm and Haas Co.). Other dispersants that can be used are 8300 068 7 Triton X-100 (alkylarylphenoxypolyethoxyethanol), Triton X-301 (alkylaryl ether sulfate) and Triton X-405 (alkylaryl polyether alcohol), all trade names of Rohm and Haas Co.

The paint formulations of the present invention may also contain various other ingredients commonly used in the paint industry. For example, an anti-foaming agent such as Nopco NDW manufactured by Nopco Chemical Company can be used. Conventional drying agents can also be used in those cases when the paint formulation contains an alkyd resin as a component. Such desiccants include, for example, cobalt and zirconium dryers. A coalescing agent may also be used such as 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate prepared by Eastman Kodak under the tradename Texanol. Other known ingredients, such as antioxidants, preservatives, antifreezes (eg ethylene glycol) and modifiers can also be used in the paint formulations, as will be apparent to those skilled in the art.

In certain experiments, it has been found that smoked M113O4 can be combined with conventional pigments, such as titanium dioxide (1103) to produce different hues. For example, in such an experiment, smoking was mixed together with different amounts of TiO2 and the different color tones thus produced were recorded. In the same experiments, control samples containing 100% smoked Mh 2 O 3 and TiO 2 respectively for comparative purposes were also prepared. It was found that the emulsion film in the case of 100% TiO2 (C ^ Mn ^ O ^) was "single white", 10% smoked MhgO ^ (90% TiO2) was "light brown" or "beige", 40% smoked MnjO 2 (60% Ti 2) was "medium brown" and 100% smoked ^ 0 (0% Ti 2) was "dark brown" or "deep reddish brown."

The color of the emulsion film in the experiment described above 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 according to the methods outlined in the Munsell Color Book and are given in Table A below. In the column marked "Munsell No.", the first value and letter designation represent the "hue", the number following the letter designation represents the "value", and the last number represents the "Chroma" .

8300068 8

Table A Color definition% T102 smoked Hunsell no.

5 100 ON 9.5 / 90 10 5 YR 8/2 60 .40 7.5 YR 5/2 0 100 5 YR 3/4 10 Based on the quoted Munsell No. in Table A, it can easily be seen that the smoked colorant of the present invention has a coloring and modifying effect on other pigments such as TiO2 which produce certain shades such as yellow iron oxide, Hansa yellow, chromium oxide green, phthalocyanine blue, and phthalo-15 cyanine green.

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

Example 1

A water emulsion paint composition was prepared using a standard general purpose white titanium dioxide pigment of rutile grade. The composition was prepared by first combining together 60.0 g of rutile titanium dioxide, 70.0 g (pH 9.7) of thickener, ie a 20 percent solution of Thickener 745 (Rohm and Haas Co.) in water, 2.0 g of a dispersant / stabilizer, ie Tamol 850 25 (Rohm and Haas Co.), 10.0 g alkylarylphenoxypolyethoxyethanol, ie Triton 100 (Rohm and Haas Co.), 1.5 g anti-foaming agent, ie

Hevi-Duty AF agent (Interstab Chemicals Ine.), 2.0 g of polypropylene glycol, 20.0 g of a coalescing agent, ie butyl arbitol (Union Carbide Corp.), 2.0 g of 28% ammonium hydroxide and 87.5 g mixing water. After thorough mixing, 622 g of latex, i.e. UCAR 4358 (Union Carbide corp.), Was added to the mixture.

The paint composition thus prepared was spread on the surface of several test panels made of bare aluminum measuring 7.5 x 22.5 cm with a draw bar to a thickness of about 25.4 µm. The coated test panels were then cured at ambient temperature for about 1 week and then subjected to a laboratory scale fading test using ultraviolet light. In the test, the coated panels were placed on test racks and continuously exposed to a constant source of 40 ultraviolet light according to the ASTM G 25-70 Fadometer test. Test panels 8300068 9 were periodically observed for color stability and faded for periods up to 1000 hours. A valuation code was established to measure the degree of fading of the test panels and shore in the following manner: 5

Valuation code 10 - no change 9 - very slight change 8 - slight change 10 7 - moderate + 6 - moderate 5 - moderate-4 - slightly poor 3 - poor 15 2 - very poor 1 - partly failed 0 - failed.

The results of the shooting tests are given in Table B.

Each evaluation code given in the table is preceded by the letter "F" to indicate that the test is a fading test, except in the present example, when the color pigment was T1O2. TiO2 pigment produces a substantially "white" pigmentation, which will bleach after continued exposure to ultraviolet light.

Therefore, in Table 3, the abbreviation "Blch" is used to indicate bleaching of the paint formulation in this example.

Example 2

A water emulsion paint composition was prepared using the same ingredients as used in the paint formulation of Example 1, except that in this case the 60.0 g of T102 were replaced by 57.0 g of leached smoked MhgO4. The smoked MhgO4 was leached by subjecting the smoking product to hydrochloric acid. Also in this case, 73.0 g of polycarboxylic acid thickener, i.e., Thickener 485 (Rohm and Haas Co.) were used together with 480.0 g of latex, i.e.

35 UCAR 4358 (Union Carbide Corp.) in place of the 622.0 g added. The paint composition was spread on test panels in the same manner as described in Example 1 and subjected to the same fading tests. The color of the film was "dark brown" or "deep reddish brown".

40 Example 3 8300068 ✓ 10

An emulsion-type paint composition was prepared by dispersing extenders and pigments in an emulsion prepared by mixing a long oil alkyd resin, i.e., Aroplaz 1271 (Spencer Kellog Co.), containing cobalt and zircon dryers.

To 350 g of the alkyd emulsion, 4.0 g of a cellulosic thickener, ie QP 4400 (Union Carbide Corp.), 8.0 g of an anionic dispersant, ie Tamol 850 (Rohm and Haas Co.), 5 .0 g of a nonionic surfactant, ie Triton CF-10 (Rohm and Haas Co.) of the alkyl aryl ether type, 5.0 g of anti-foaming agent, 10 ie Hevi-Duty AF agent, 20.0 g of ethylene glycol added. To the carrier thus obtained, 150.0 g of synthetic red iron oxide, 35.0 g of cutting pigment, ie Mica 325, sold by English Mica Company, 75.0 g of CaCO 3, 50.0 g of a rust-inhibiting pigment, modified barium metaborate , ie Busan 11-Ml (trade name 15 from Buckman Labs, Ine.) added and dispersed using a Cowles dissolver. After thorough mixing, 500 g of styrene-acrylic copolymer latex, i.e. UCAR 4341 (trade name of Union Carbide Corp.) and a coalescing agent, were added.

As in the previous examples, this paint formulation was spread on bare aluminum test panels of the size 7.5 x 22.5 cm with a wound wire rod applicator for a wet film (Meyers) to obtain a dry film thickness of 25.4 µm . The applied film or coating was then cured at ambient temperature. The test panels were then placed on test racks and subjected to the same fading tests.

Example 4

An emulsion-type paint composition was prepared by mixing an acrylic emulsion, i.e., Rhoplex MV 23 (Rohm and Haas Co.) together with smoked MnjO 2. The composition was as follows: 59 g of water, 25.0 g of a 20% polyacrylate thickener, ie Thickener E845 (Rohm and Haas Co.), 17.6 g of a 40% dispersant, ie QR-681 40% ( Rohm and Haas Co.), 2.0 g of benzyl ether of octylphenol-epoxyethane addition product as surfactant, ie Triton CF-10 (Rohm and Haas Co.), 28.0 g of ethylene glycol, 5.7 g of anti-foaming agent, 35 i.e. Foamaster NDW (Diamond Shamrock Co.), 12.0 g zinc oxide pigment, ie ΑΖ0 77 (American Zink Co.), 53 g CaC03> 2.1 g Skane M-8 (Rohm and Haas Co.) containing the biocide (2 -n-octyl-4-isothiazolin-3-one) and 151 g of smoked Mtt30. After thorough mixing, 667.0 g of acrylic latex, ie Rhoplex MV 23 (Rohm and Haas Co.), 7.0 g of 28% ammonium hydroxide 40 and 5.7 g of coalescing agent, 2,2,4-trimethyl-1,3-pentanediol -monoisobu-8300068 c.

* 11 tyrate, i.e., Texanol (Eastman Kodak Co.) added to the mixture.

Test panels (aluminum) were coated with this paint formulation in the same manner as described in the previous examples, and the coating was cured at ambient temperature. The color of the film 5 was again "dark brown" or "deep reddish brown". In principle, there was no difference in color between the leached and non-leached smoked MhgO 2. The test panels were then subjected to the same firing tests.

The results of the fading tests using the 10 different paint compositions as described in Examples 1-4 are shown in Table B.

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From the results of the fading test shown in Table B, it appears that water emulsion paint compositions containing smoked Mn 2 O 2 pigments of the present invention exhibit color stability and fade resistance equal to 5 or better than that of paint compositions containing conventional pigments of the prior art. In particular, it is noted that the paint compositions in Examples 2 and 4 containing smoked MngO 2 as color pigments showed only a small amount of fading, while on the other hand the paint composition used in Example 3 using of red iron oxide pigment, exhibit a much greater degree of fading (ie, from F-10 at 50 hours to F-3 at 1000 hours). As a further comparison, it appears from the results of Table B that paint formulations prepared using conventional titanium dioxide (TiCl 3) as a "white" pigment showed signs of fading (Example 1) after only 50 hours of exposure to ultraviolet light. It will further be apparent from the results of Table B that the smoked pigment can be used in a wide variety of paint formulations using various ingredients such as thickeners, dispersants, stabilizers, anti-foaming agents, preservatives, etc., without any harmful effect on the applied coating. Furthermore, it may be noted from the test that paint formulations using caustic smoked as color pigments were not as stable as paint formulations using non-caustic smoked 25 M 2 O 2. However, the leached smoked ΗηβΟ ^ when used as a colorant showed better fade resistant properties compared to synthetic red iron oxide.

8300068

Claims (5)

1. Water emulsion paint composition Mainly consisting of an acrylic emulsion, a thickener, dispersants and a color pigment with improved color stability and flak resistance of the paint formulation, characterized by the presence of a color pigment consisting of finely divided smoked ΜηβΟ ^ particles. Water emulsion paint formulation according to claim 1, characterized in that the smoked Mn 2 O 2 has the following properties: (a) a chemical composition containing at least about 90% by weight Contains 10 Mn 2 O 2, the balance being a mixture containing calcium oxide, magnesium oxide, potassium oxide, and silica with less than about 1 wt% free manganese metal and (b) a particle size, where 98% is less than about 10 micrometers. Water emulsion paint composition according to claims 1 or 2, characterized by the presence of about 40 to 65% by weight of a latex composition, about 0.5 to about 12% by weight of a thickener, about 0.2 to 2, 0 wt% of a dispersant, about 0.2 to 2.0 wt% of a surfactant, about 0.1 20 to 1.0 wt% of an anti-foaming agent, about 0.3 to 6.0 wt .% of a coalescing agent, about 0.1 to 1.5 wt% of a preservative, about 0.0 to 15.0 wt% of an excipient, about 5.0 to 30 wt% of smoked MnjO 2, about 0.0 to 25 wt% T1O2 and the rest water. The water emulsion paint composition according to claim 3, characterized by the presence of 0 to about 8.0% by weight of an antifreeze agent. Water-emulsion paint composition according to claim 3 or 4, characterized by the presence of 0 to about 10.0% by weight of an alkyd resin. 8300068