Patent Grant
9771484
The present invention is related to the procedures for the preparation of additives for use in coatings applied to structural elements or as finishing for materials susceptible to combustion, such as wood and its derivatives, with the purpose being to provide properties that are flame retarding once the material to be protected is covered; specifically, the invention discloses a procedure for the preparation of an additive formulated with a metallic hydroxide and a mix of a dispersant, a compatible vehicle (an organic solvent), water and resin that allow the easy incorporation of the additive into the coating.
It is well known that the construction of residential buildings or buildings used for the realization of other activities: work, recreation, etc. have a need to incorporate means that help control fires and slow the expansion of a fire. For example, some countries have released regulations on materials for the construction of buildings, as much as for the fabrication of the furniture that is contained within them.
The majority of the furniture has coatings that have esthetic purposes as well as for the protection the material which it is made from, nonetheless, the majority of these coatings are inflammable, which when added to the natural combustible property of the base material, generates an excellent source for the spreading of the fire.
Coatings that are flame retarding can be found Such flame retardants are usually made of phosphates, silicates, borates (intumescent). An intumescent flame retarding material such as those mentioned is characterized by its reaction to fire: first, it forms a foam layer that transforms into ash, which then forms a crust that impedes the penetration of the fire into the base material.
The metallic hydroxides, on the other hand, are used as flame retarding additives, for example, in polymers, with various applications: coatings for cables, furniture, roofing tiles, etc. Magnesium hydroxide has an advantage over other types of flame retarders because it is environmentally friendly and it does not release toxic fumes when utilized as a smoke suppressant.
There already exists a large variety of alternatives to control the problem of fire expansion, through the use of metallic hydroxides. Some examples are mentioned below.
In patent EP 1156092, it describes the fabrication of an adhesive of two components that is created by using magnesium hydroxide, mentioning that said adhesive can be used as a varnish with flame retarding properties.
In the U.S. Pat. No. 6,448,308, it includes magnesium hydroxide as part of the formulation of a coating that is flame retarding that has a base of red phosphorus. The use of the magnesium hydroxide is specifically used for reducing the production of phosphoric acid during the process of flame inhibition.
In U.S. Pat. No. 4,849,298, it describes the use of aluminum hydroxide in the formulation of paints adding it directly to the paint and also, it is used as a substitute for conventional filler in paints (TiO2, for example). The patent describes the effect of the flame retarding properties of coatings prepared with this additive.
By integrating the properly treated magnesium hydroxide into traditional wood coatings, such as varnishes and sealants, or architectonic, such as paints, waterproofing, etc. excellent flame retardation and smoke suppression effects are achieved. The coating thus prepared does not change its final appearance (brightness, transparency, covering power, mechanical strength, etc.)
In light of the problems seen in the previous inventions, one objective of the present invention is to provide an additive that is a flame retarder and a smoke suppresser when used in the preparation of coatings designed to cover and protect surfaces that are susceptible to combustion, and whose efficiency would be better than those offered by the present flame retardant coatings.
Another objective of the present invention is to provide a flame retarding additive that is easily incorporated into the coating before being applied to the surface it is going to protect.
One more objective of the present invention is that the additive incorporates as the flame resistant ingredient a material that does not generate toxic residues when such is the case that it is exposed to flames.
Another objective of the present invention is for the flame retarding ingredient to be of the family of metallic hydroxides.
Still another objective of the present invention is that the flame retarding ingredient of the additive of the invention does not form groupings in the interior volume of the coating before its application.
One more objective of the present invention is for the flame retarding ingredient of the invention's additive to be distributed in a uniform (homogeneous) manner in the film of the final coating on the surface to be covered and protected.
Another objective of the present invention is that the flame retarding additive does not interfere with the fundamental properties of the coating to which it is added, as an example, the transparency of a varnish.
One more objective of the present invention is the flame retarding ingredient of the additive presents grain finesse similar to that of the coating in which it is included.
The additive of the coating prepared with the procedural ingredient of the invention has as a source of its flame retarding properties a metallic hydroxide, preferably of magnesium, with individual characteristics according to the size of the particle, that is submitted to a treatment associated with the nature of the coating into which it will be incorporated, in a way that the resulting additive is able to be efficiency integrated into the coating selected.
Some characteristics of the additive created by the procedure described in the invention are:
The invention's procedure produces a paste or preferably a suspension of particles of metallic hydroxides treated with other compatible vehicles (organic solvents or water), dispersants and eventually surfactants, in a substance made up of an organic solvent, a dispersant, a resin and in some cases water, that show the following advantages:
For a better understanding of the description that follows, the attached FIGURE should be regarded when reading the description.
The additive prepared according to the procedure of the present invention is created from a metallic hydroxide with an average particle size selected from the range of 1 nanometer to 10 microns, preferably being monodispersed, and having a wide variety of sizes and with a purity of at least 90%.
The metallic hydroxide particles are submitted to a treatment for their integration into the final coating, so that they can be separated from a hydroxide in an aqueous, organic or dust suspension, without which the compatibility between the initial hydroxide vehicle and the base of the additive that will be formed would be limited.
In the preferred form of the present invention, the metallic hydroxide is magnesium hydroxide. It has as an advantage in addition to its flame retarding properties, that it helps control the emission of fumes upon releasing the water when the elements in the reaction break down (1);
With reference to
In zone I, or the pretreatment phase, the block (10) represents the flame retarding ingredient that will be used for the preparation of the additive, preferably being a wet paste of metallic hydroxide although for some very specific applications that require the absence of water, it is preferable to use a hydroxide in a dry powdery form. As was mentioned before, the hydroxide is formed by particles with an average size in the range from 1 nanometer to 10 microns and with a purity of at least 90%. This material is added to the following block.
The block (20) represents an operation called the “change of vehicle” in which the wet paste of the metallic hydroxide is washed in order to displace the water contained therein and substituting a “compatible” organic solvent, that is, it is incorporated without provoking separation of the stages, with the solvent or the thinner of the final application (the “objective” coating), which will stop in the moment the formation of lumps when it comes in contact with the objective coating; the process takes place with strong agitation, preferably for between 5 and 30 minutes, or for the time deemed necessary. The mix will be maintained in agitation in a turbulent pattern by means of a diffuser with a sharp disk or other device that allows the peripheral velocity to be at least 2 m/sec and up to 30 m/sec. After the agitation, the separation of the stages results and the process can be repeated until a residual humidity of less than 5% is obtained when in the solid state.
When by the nature of the solvent or the thinner and of the resin of the final application, the metallic hydroxide could react, it is evaluated, as is indicated by the block (15), in order to give the particles a surface treatment (16) before the operation of the “change of vehicle” (20), using conventional surfactants compatible with the objective coating.
The process of the “change of vehicle” (20) serves to guarantee that the hydroxide particles do not group together in the dispersion process (50) in Zone II, in the incorporation to the coating or in the application of the same on to the surface to be treated.
The block of decision (30) indicated that in case that the tolerated residual humidity in the additive is very low, close to zero, due to the nature of the resin and solvents or thinners in the objective coating and once the “change of vehicle” (20) stage is complete, the solid phase is summated to a process of drying (40), where the temperature of the operation in said drying stage always needs to be lower than the boiling point of the vehicle. The operation continues until the tolerated residual humidity for the objective coating is obtained.
The result of the operation is a “dry” powder of hydroxide that can be stored for the later preparation of the additive. The product obtained by this means can remain as a “dry” powder dispersible for periods of 12 months.
If in the final application a humidity content of 5% is tolerated, the drying stage that is represented by block (30) is omitted.
The product obtained, be it “dry” or wet, coming from one of the two previous steps of the first phase of the process then passes to a process of dispersion (50), in Zone II, which is adequately identified with the preparation of the additive ready for use in the objective coating that is the material of the present invention.
In this stage, the paste or the “dry” powder coming from blocks (20) or (30), are added to a process of dispersion (50) where a compatible resin and a compatible dispersant are added to the objective coating, according to the following table:
The dispersion (50) is done by means of an agitator or a disperser having a peripheral velocity of between 15 and 30 m/sec. The viscosity of the mix is adjusted to that of the objective coating by the addition of the solvent or the thinner that preferably is of the same base that will be used with the coating or at least should be compatible with it. The percentage of dispersant in the mix is maintained between 0.5 and the 10% in relation to the hydroxide in the dry base.
The product (60) obtained from the process of the dispersion (50) is the additive of the invention, the same product that can be in the preferred form, a formulation with up to 99% of its weight in metallic hydroxide.
Among the advantages that the additive has obtained by the process of the invention are that as a consequence of the treatment of the change of vehicle in stage (20) and the mix with resins and dispersants in stage (50), the product is completely compatible with the objective coating for that which was prepared during the selection of the appropriate surfactant, resin and dispersant according to the table previously included, furthermore, maintaining a high grade of homogeny in the dispersion of the metallic hydroxide particles in the formation. For that which when added to the objective coating, the additive will integrate quickly and easily and it is guaranteed that the particles maintain the homogeny throughout the whole volume and thus, in the layer of the coating after the application onto the surface it is to protect.
In the preferred means of the invention, useful in the case of transparent finishes, particles with an average size in the range of nanoparticles with a low variability (monodisperse) are used with those that the properties of the transparency of the varnish are not altered, that which is not guaranteed with particles of larger sizes or with a non homogenous sample or a sample of wide dispersion.
For that reason, it is suggested that in the preparation of an additive for transparent varnishes to use particles from the extreme low end of the average size range. In the same way, with opaque coatings it is acceptable to use particles of larger sizes, and in the texturized finishes, particles from the extreme high end of the range can be used.
The use of particles from the extreme high end of the range (10 microns) does not guarantee a homogenous distribution in the layer of the coating on the surface that it is to protect, and thus, the flame retardant efficiency is considerably diminished.
Table 2 shows a summary of the selections of the reagents and the parameter values recommended for a variety of classes of conventional coatings used for common applications, that is possible to create additives, following the procedure according to the present invention, that will offer the characteristics of being easy to incorporate into the objective coating, homogenous (uniform) distribution of the particles of the flame retarding and smoke repressing ingredient, and conservation of the desired properties of the coating to name a few.
For a better understanding of the use of the data contained in tables 1 and 2, the following examples are realized according to standards ASTM D1360. They offer illustrations of diverse alternatives for the creation of the additives according to the procedure of the present invention.
The flame retarding additive for the alkydalic varnish, prepared in Example 1, can be mixed in different proportions with any alkydalic varnish that is found on the market. Also, the flame retarding additive for the nitrocellulose based sealer prepared in Example 2 can be mixed with any nitrocellulose based sealer that is on the market.
Frequently, a wood varnish is used for its sealant properties as well as its varnishing properties. Table 3 shows different combinations of sealers and varnishes mixed with the flame retarding additives prepared in Examples 1 and 2, and the results upon submitting them to the flame test according to the ASTM D1360.
Table 4 shows the rest of the examples of the additives prepared with different types of resins that have applications to different types of coatings.
The effects of the use of the additive with magnesium hydroxide in the wood coatings in the previous tests are illustrated in Table 5. They show the result of the examples of the application of the prepared additive according to the previously described procedure.
The effect of the flame retardant when the coating includes magnesium hydroxide can be clearly observed. In the physical tests, it can be seen that that there is no change in the final appearance of the coating with the additive of the invention after its application with respect to the appearance that the coating offers without the additive; this is also valid for coatings that have a high transparency such as varnishes.
In this aspect, the size of the hydroxide particles is important, as well as the uniformity of the size and the homogeny of the distribution of the particles in the final layer of the coating once applied.
As has been described and illustrated through the previous examples, the present invention is directed to the preparation of an additive that has the properties of a flame retardant and a suppresser of smoke, without affecting the properties of the coating to which it is added.
In the examples, there has been used some common coatings for the protection of surfaces, in particular wood and its derivative, as can be seen by a technician with knowledge of the art, these examples do not limit the reach of the invention but they are to be illustrative of the same, and the use of the additive in other coatings for the application to other surfaces, is found to be also within the reach of the present invention that, thus should be considered in light of the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| NL/A/2006/000089 | Nov 2006 | MX | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/MX2007/000046 | 4/3/2007 | WO | 00 | 3/1/2011 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2008/056966 | 5/15/2008 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 2552314 | Gloss | May 1951 | A |
| 4145404 | Miyata et al. | Mar 1979 | A |
| Number | Date | Country | |
|---|---|---|---|
| 20120312190 A1 | Dec 2012 | US |
