CA1257034A - One-component coating composition and method of producing a protective coating - Google Patents
One-component coating composition and method of producing a protective coatingInfo
- Publication number
- CA1257034A CA1257034A CA000438512A CA438512A CA1257034A CA 1257034 A CA1257034 A CA 1257034A CA 000438512 A CA000438512 A CA 000438512A CA 438512 A CA438512 A CA 438512A CA 1257034 A CA1257034 A CA 1257034A
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- CA
- Canada
- Prior art keywords
- coating composition
- weight
- isocyanate
- component coating
- polyurethane
- Prior art date
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Abstract
ABSTRACT
A one-component coating composition which hardens under exposure to moisture contains 15 to 70% by weight polyurethane-forming isocyanate, 5 to 25% by weight light, liquid OH-groups-containing, low molecular, aromatic hydrocarbon resin, 0.2 to 2% by weight anti-settling agent, 10 to 35% by weight flake-shaped exten-der, 2 to 25% by weight coloring pigments, 1 to 5% by weight moisture absorbing agent, and at least 5% by weight known resin solvent. This coating composition can be applied in the usual way on a dirt- and dust-free base with a thickness of at least 20 µm and hardened solely on exposure to moisture of the surround-ing atmosphere. The coating composition is particularly adapted for the protection of all kinds of roofs, the coating of concrete, the corrosion protection of steel concrete, the coating of steel and/or, the sealing of flat roofs covered with tar board.
A one-component coating composition which hardens under exposure to moisture contains 15 to 70% by weight polyurethane-forming isocyanate, 5 to 25% by weight light, liquid OH-groups-containing, low molecular, aromatic hydrocarbon resin, 0.2 to 2% by weight anti-settling agent, 10 to 35% by weight flake-shaped exten-der, 2 to 25% by weight coloring pigments, 1 to 5% by weight moisture absorbing agent, and at least 5% by weight known resin solvent. This coating composition can be applied in the usual way on a dirt- and dust-free base with a thickness of at least 20 µm and hardened solely on exposure to moisture of the surround-ing atmosphere. The coating composition is particularly adapted for the protection of all kinds of roofs, the coating of concrete, the corrosion protection of steel concrete, the coating of steel and/or, the sealing of flat roofs covered with tar board.
Description
~2570~4 The invention reIates to coating compos~tions which due to their content of polyurethane-forming isocyanate harden chemically. More particularly, the invention relates to one-component coating compositions of this kind which in ready mixed form are stable on storage under exclusion of moisture, but harden on exposure to moisture. Moreover, the invention relates to a method of producing a protective coating using such coating compositions and various applications thereof. The coating compositions are particularly suitable for the protection of building structures such as the protection of roofs of any kind, the sealing of flat roofs covered with tar board or tar paper, for the coating of concrete and/or for the corrosion protection of steel concrete.
Coating compositions for the protection of building structures are known. The known preparations include, for example, water-dilutable acrylates. How-ever, these acrylates had to be applied in several layers and, in practice, did not afford satisfactory protection. A further known coating composition consists of a two-component epoxy resin system. How-ever, this system was only workable under specific temperature and humidity conditions and difficulties occurred with regard to the pot time. Moreover, coating compositions based on combinations of coal tar and polyurethanes are known (see "Farbe und Lack", 83, p. 701-705 (1977)). Coal tar is typically character-i~ed by its black color and viscous consistency and consists practically exclusively of aromatic compounds which, besides carbon and hydrogen, contain a certain percentage of other atoms such as oxygen, nitrogen and sulphur. A portion of these heteroatoms are present in hydroxyl and amino groups. Accordingly, such tar con-tains active hydrogen atoms which can react with ~257034
Coating compositions for the protection of building structures are known. The known preparations include, for example, water-dilutable acrylates. How-ever, these acrylates had to be applied in several layers and, in practice, did not afford satisfactory protection. A further known coating composition consists of a two-component epoxy resin system. How-ever, this system was only workable under specific temperature and humidity conditions and difficulties occurred with regard to the pot time. Moreover, coating compositions based on combinations of coal tar and polyurethanes are known (see "Farbe und Lack", 83, p. 701-705 (1977)). Coal tar is typically character-i~ed by its black color and viscous consistency and consists practically exclusively of aromatic compounds which, besides carbon and hydrogen, contain a certain percentage of other atoms such as oxygen, nitrogen and sulphur. A portion of these heteroatoms are present in hydroxyl and amino groups. Accordingly, such tar con-tains active hydrogen atoms which can react with ~257034
- 2 ~
isocyanate groups. T~pically, thexefore~ mixture$ of coal tar and polyurethane forming isocyanate are not one-component coating compositions.
In general, it can be said that processing of the known coating compositions requires an air temperature of about 10C and a relative humidity of below 80~
To achieve useful protection, the known coating composi-tions have to be applied in an amount of 170 g/m2 per coat. Even when complying with these conditions the known coating compositions were not fully satisfactory.
In their practical applications the following diffi-culties became particularly apparent:
- the diffusability of the coating composition was insufficient;
- the coating composition had to be applied at least twice;
- the hardened protective coating had only a low elasticity;
- due to strong weathering reworkability of the protective coating was poor;
- with time strong chalking occurred (for this reason the respective directions for those known systems provide for renewal after at least five years);
- the coating composition can only be applied in good, dry weather;
- the finished protective coating exhibits only slight pore sealing;
- the known coal tar/polyurethane-forming isocyan-ate mixtures necessarily have the disadvantages connected with coal tar such as the black color, the bleeding of tar through covering coatings, and the decomposition of coal tar components by W-radiation.
Accordingly it is an object of the present inven-tion to provide a one-component coating composition for the protection of building structures which shows improvements over at least some, preferably all, of the disadvantages of the known systems.
The coating composition according to the in-vention is a one-component coating composition which hardens under exposure to moisture and which comprises:
15 to 70% by weight polyurethane-forming iso-cyanate, 5 to 25~ by weight light-liquid, OH-grou~s-con-taining, low molecular, aromatic hydrocarbon resin, 0.2 to 2% by weight anti-settling agent, 10 to 35% by weight flake-shaped extender, 2 to 25% by weight coloring pigment, 1 to 5~ by weight moisture-absorbing agent, and the remainder,at least however 5% by weight,resin solvent.
In contrast to the known coal tar the hydrocarbon resin according to the invention is a colorless or lightly yellow oil so that the inventive composition results in a clear and light, even white, coating which nevertheless exhibits the advantageous properties of the polyurethane/coal tar coating. When exposed to the sunlight, the light coatings according to the invention compose, due to UV-radiation, to a lesser extend than the known coal tar containing coatings.
Moreover, it is an object of the present invention to provide a method of producing a protective coating by applying the inventive one-ccmponent coating composition to a clean base and allowing the composition to harden under exposure to moisture in the surrounding atmos-phere.
Due to the fact that the inventive coating compo-sition is a one-com~onent system, the composition can,on exclusion of moisture, be stored for substantially ,~P .~ i' ~25~034 unlimited time while hardening w-ithin about lO to 30 minutes after application to a base a~d on expos~re bo moisture in the surrounding atmosphere so that, if desired, already after about 30 minutes one or more additional coating(s) can be applied. After about 15 to 20 hours the total protective coating is completely hardened and can be exposed to the intended load.
The coating composition according to the invention is suited for producing protective coatings for the protection of building structures in general. Preferred applications include the protection of roofs of all kinds including the sealing of flat roofs covered with tar board or tar paper, the coating of concrete and the corrosion protection of steel concrete.
Further object and advantages of the invention will become apparent from the following description and claims.
In the following the advantages and characteris-tics of the coating composition according to the invention are listed in abbreviated form:
- the coating composition is still workable at temperatures of less than 5C;
- the coating composition is workable even at relatively high atmospheric humidity, for example, at humidities of more than 90~;
- the coating composition is self-spreading;
- the coating produced with the coating composi-tion affords excellent protection against ultrava let radiation;
- the finished protective coat exhibits good reflection values in respect of radiation of light and heat;
- even when the protective coat is thin, for ex-ample in the magnitude of only 50 ym, the finished coat exhibits high pore sealing;
~257034 - the finished protecti~e coat shows good elasticity and high adhesive strengths - even after weather~ng the protective coat is reworkable without problem;
- prior to application of the coating composition only the usual simple pre-treatme~t of the base is required;
- the protective coat is flame-resistant; and - even when the protective coat is thick, for example thicker than 200 ~m, no cracking of the coat occurs during hardening.
In the following the invention is described in more detail with reference to preferred embodiments.
The coating composition according to the inven-tion comprises the following ingredients in the given proportions:
15 to 70% by weight polyurethane-forming iso-cyanate;
5 to 25% by weight light, liquid, OH-groups-c~n-taining, low molecular, aromatic hydrocarbon resin;
0.2 to 2% by weight anti-settling agent;
10 to 35% by weight flake-shaped extender;
2 to 25% by weight coloring pigments;
1 to 5% by weight moisture absorbing agent; and at least 5% by weight resin solvent.
In addition to the listed nec~ssary ingredients the coating composition according to the invention can contain additives and supplements commonly used in the resin, varnish, lac~uer or related technologies such as, anti-bacterial or anti-fungal agents, additives inhibit-ing decomposition ~y light, heat and/or corrosive influences, and other commonly used additives adapted for specific requirements (for example to suppress blister formation) or anti-drip agents.
12570~4 - 6 .
As pol~ureth~ne~forming isocyanates kno~n di-~
isocyanates, triisocyanates and low ~olecular poly isocyanatesmay be used such as, for ex~le, the grouP of ~socyanates available under the trademark "Desmodur".
Good results were obtained with toluylene diisocyanates, whereby 2,4- as well as 2,6- toluylene diisocvanate or the commercially available isomer mixture may be used.
Furthe~more, diphenylmethane-4,4'-diisocyanate or hexamethylene-1,6-diisocyanate can be used as poly-urethane-forming isocyanate.
As further essential ingredients the coating composition according to the invention contains a liquid OH-groups-containing aromatic hydrocarbon resin.
In contrast to the known tar, in particular, coal tar, the hydrocarbon resin according to the invention is a light, i.e. colorless to light yellow, material with a brightness according to Barrett of between about 0.5 and 2.
The hydrocarbon res;n is liquid and has at 25C
a viscosity of between about 700 and 2,000 cP.
The resin is a low molecular, aromatic material with a~ average molecular weight of 600. The density of the hydrocarbon resin at 20C is between about 1 and 1.2 g/cm3.
The acid number of the hydrocarbon resin is preferably between about 0.2 and 3.
The hydrocarbon resin necessarily contains a certain portion of OH-groups. Preferably, these are aromatic OH-groups which result from a prior "phenol modification" or "activation". Preferably, the hydrocarbon resin contains OH-groups,particularly aromatic OH-groups, in an amount of about 2 to 4%
by weight of the resin.
The hydrocarbon resin is preferably free of water and solvents. The amount of volatile components in the hydrocarbon resin ~s less than~l0% and can in certain commercially available products be between about ~25~03~
~ 7 -5 and ~% by wei~ht.
Hydrocarbon resins of this kind are known in the art and are offered by commerc~al establ~shments specifically for the requirements of the resin and related industries. To descri~e these materials terms such as special light resistant tar", "Albino-tar" etc. are used in the art. For example, materials available under the tradèmark "aktivierte VFT Spezial-Flussigharze" from VFT-Vertriebsgesellschaft fur Teererzeugnisse mbH, Essen,Federal R~Iblic o~ G~Eny, may be used as hydrocarbon resin according to the invention.
Anti-settling agentsfor the present kind of coating compositions are known in the art. Known anti-settling agents which are useful according to the invention include, for example,montmorillonite, silica, hydrogenated castor oil and the like.
Flake-shaped extenders or fillers are also known. Flake-shaped extenders which are useful ac-cording to the invention include, for example, talc,barium sulphate, flaked pigments based on Si/Al-oxides and similar filler materials. The extenders according to the invention should contain little or, preferably, no carbonate and/or CO2-releasing components so that in admixture with polyisocyanate stability on storage is assured.
Coloring pigments for the present kind of coating compositions are also known. These pigments convey to the protective coat the ability to reflect 3Q light and heat and give the coat a certain color.
Suitable coloring pigments are commercially available, for example, under the trademarks "Sicominp~gment", "Heliogenpi~ment", "Litholpigment" and the like.
According to a further aspect of the invention at least a portion of the "coloring" pigments consists of aluminum powder. Preferably, a flake-shaped alum-~num powder having an area extension of less than 45 ,um ~Z57034 ` 8 .
is used. Prefe~ably, the alum~num component amounts to about 20 to 80~ hy weight of the coloring pigment.
In a particularly preferred embodiment the coating composition contains about 1 to 6~ aluminum pigment relative to the total weight of the coating composition.
Su~table moisture-absorbing or mois~ure-extracting agents include finely divided natural and synthetic zeolites (for example "Zeolith l-Paste" (trademark) available from Bayer AG), and molecular sieves made of alumina and silica compounds, which may be supplemented with titanium. Moreover, agents which bind or absorb water chemically such as monoisocyanate can also be employed. Such moisture-binding, moisture-absorbent or moisture-extracting agents are also commercially available.
As resinsolvents the known solvents and solvent mixtures are suitable. For example, ~ommonly available mixtures of aromatics with a molecular weight of between 100 and 200 proved useful. Furthermore, solvents commonly used in the resin industry based on aliphatic esters such as acetates, propionates and/or butylates can be employed. Higher esters are less suitable, because the resulting drying time may be too long.
The preparation of the coating composition according to the invention can be effected according to techniques commonly used in the resin industry.
Generally, the ingredients are placed into a vessel in the required proportions and mixed with a speed stirrer or dissolver. It proved useful to place a mixture of polyurethane-forming isocyanate and hydro-carbon resin into the vessel and then successively add the other ingredients, whereby the moisture-ab-sorbing agent is added last. Stirring for a period of 10 to 20 minutes at room temperature was found to give satisfactory results. A slight rise in tempera-ture, for example up to about 40C, may occur. This is probably not attributable to any reaction heat, but ~2S~034 to shearing forces. Finally, the re~uired amount of solvent is added to ensure workability of the material.
Following this the material is again mixed for a short period yielding a self-spreading, structurally viscous composition which is ready for use.
If required, the coating composition can be stored. The storage stability at room temperature is at least 6 months. Individual samples were stored for more than 12 months without noticable increase in viscosity and/or decrease in reactivity.
Since the coating composition according to the invention is a one-component system, no pot time worth mentioning is given. After opening of the storage container the composition should be applied speedily otherwise film formation and slow through-reaction takes place due to the presence of atmospheric moisture.
Application of the coating composition to the intended base can be effected according to conventional methods such as by way of a roller or by spraying.
For example, the Airles (trademark) spraying method which employs high pressure was found useful.
The coating composition is applied to the provided base in a thickness of at least 20,um. Pre-ferably the thickness of the coating is between about 50 and 70Jum. It is also possible to apply several coats, each new coat being applied after each previously applied coat has substantially hardened. For example, a coat which is 45~m thick dries at the ambient conditions within about 15 minutes and is reworkable after about 30 minutes so that one or more additional coat(s) can be applied.
After about 18 hours the protective coating is com-pletely hardened and firm and can be exposed to the intended load. After weathering and/or aging of the resulting protective coating,even over a period of one year or longer, this coating can,without difficulty, again be coated with the same inventive coating composition.
i , . ..
~s lQ ~
The preparation of the hase does not call for special measures. It is sufficient if the base is free of dirt and dust as can be ach~eved by s~mple sweeping. No special requirements regarding the dry-ness of the base has to be met. The coating compositionaccording to the invention can be applied to a moist, but not quite wet area without effecting either the hardening and setting or the quality of the finished protective coating.
After application of the coating composition to the base,the composition hardens by itself under the influence of the moisture in the surrounding atmos-phere without necessitating any special measures.
According to a further aspect of the invention there is provided a one-ol~onent composition which hardens under exposure to moisture and which within the framework of the above described composition contains a relatively small amount of polyurethane-forming isocyanate. Preferably, this specific coating composition comprises:
15 to 40% by weight polyurethane-forming isocyanate;
5 to 25% by weight of the above described hydrocarbon resin;
0.5 to 2% by weight anti-settling agent;
15 to 35~ by weight flake-shaped extender;
5 to 25% by weight coloring pigments;
1 to 5% by weight moisture-absorbing agent; and the remainder, at least however 5% by weight, ~ mon resin solvent.
In this embodiment, too, the coloring plgments contain a certain portion of aluminum powder. Prefer-ably, the portion of aluminum powder amounts to between 20 and 80% by weight of the coloring pigment. In a particularly preferred embodiment the amount of poly-urethane-forming isocyanate is 15 to 30% of the total weight of the coating composition. Toluylene di-, ~2s7a34 --` 11 ~`
isocyanate containing isocyanate groups in an amount of about 5.5 to 7.5% of the t~tal weight of isocyanate is preferred as polyurethane-forming ;socyanate for this embodiment.
This "reIatively isocyanate-poor" embodiment of the invention is well suited for the protection of building structures due to its good elasticity, its high adhesive strength on various materials and due to its resistance to UV-radiation. This embodiment is particularly suitable for the protection of roofs of all kinds such as, for example, Eternit (trademark) roofs, roofs insulated with PU-Hartschaum (trademark) and the like. A further application in the art of roofs is the foam coating, namely, the roof foam coating of so-called reverse roofs. Moreover, this particular coating composition is suitable as protect-ive coating for engineering constructions, industrial and energy construction, steel construction, ship construction, off-shore construction and the like.
If this particular coating composition is used to coat steel, prior sand blasting (Sa 2.5) is recommended.
To achieve especially good corrosion protection the application of the coating composition may be preceded by priming. Moreover, this particular coating com-position is suitable for the protection of concrete and for the corrosion protection of steel concrete.
In all cases excellent resistance to radiation, light, heat and/or corrosion influences is achieved.
A further specific embodiment of the invention contains within the framework of the above described composition a relatively high portion of polyurethane-forming isocyanate. Preferably, this specific coating composition comprises:
40 to 70% by weight polyurethane-forming isocyanate;
5 to 25~ by weight hydrocarbon resin;
0.2 to 1% by weight anti-settling agent;
~ ~5703~i ~ 12 .
10 to 20~ by weight flake-shaped extendex;
2 to 15% by ~eight coloring pigments;
1 to 4~ by weight moisture-absorbing agent; and the remainder, at least however 5%by weight, resin solvent.
In the coating composition according to this particular embodiment at least a portion of the color-ing pigment consists of aluminum powder. Preferably the portion of aluminum powder amounts to 20 to 80% of the total weight of the coloring pigments.
This"relatively isocyanate-rich" coating compo-sition contains as polyurethane-forming isocyanate preferably diphenylmethane diisocyanate, especially a diphenylmethane diisocyanate containing isocyanate groups in an amount of 9 to 12% of the weight of the isocyanate. Particularly preferred is a mixture of different diphenylmethane diisocyanates which differ in their isocyanate content. In this respect good results were obta~dwhen the total amount of 40 to 70~
by weight of polyurethane-forming isocyanate (relative to the total weight of the coating composition) con-sists of a) 30 to 50% by weight diphenylmethane diiso-cyanate containing isocyanate groups in an amount of 8 to 9% of the total weight of isocyanate; and b) 10 to 20~ by weight diphenylmethane diiso-cyanate containing isocyanate groups in an amount of 14 to 17% of ~he tota~ weight of isocyanate.
Such a relatively isocyanate-rich coating com-position containing different diphenylmethane diiso-cyanate yields after exposure to moisture a lightly foaming coating. The latter has a joint-sealing effect, particularly in coating and sealing of roofs which are covered with tar board. In spite of this foam formation the resulting film is highly pore-sealing and water-impervious. This particular coating composition is workable at air temperatures o~ from 5 to 40~C and also at high atmospheric moisture, for example at a relative humidity of over 90~. This coating composition isi on the one hand,self-spreading and can, on the other hand, ~e applied in thick layers so that, for example, in one application coats having a thickness of up to 200 ~m or more can be achieved.
On hardening the composition forms a lightly foaming film which evens out roughness of the base and which seals the joints. The coating resulting from this particular coating composition also exhibits high pore-sealing, high elasticity and high adhesive strength.
In view of the preferred application of this particular coating composition for the sealing of flat roofs covered with tar board this coating composition pre-ferably contains resin solvents based on aliphatic esters such as acetates, propionates and/or butylates so as to avoid partial and/or complete dissolving of the tar-constituents in the tar board by aromatic solvent components.
This particular coating composition can be applied in one step up to a thickness of 1000 ,um without encountering adhesivity problems or the like.
As previously indicated, this particular coating composition is especially adapted to seal flat roofs covered with tar board. To this effect the coating composition is applied with a thickness of at least 50 ,um. Preferably, at least 500 g coating composition are applied per s~uare meter of tar board. Due to the light foam formation which occurs on hardening this coating composition enters joints, overlapping areas and border areas of the tar board sheets and provides sealing of joints which lasts for many years.
isocyanate groups. T~pically, thexefore~ mixture$ of coal tar and polyurethane forming isocyanate are not one-component coating compositions.
In general, it can be said that processing of the known coating compositions requires an air temperature of about 10C and a relative humidity of below 80~
To achieve useful protection, the known coating composi-tions have to be applied in an amount of 170 g/m2 per coat. Even when complying with these conditions the known coating compositions were not fully satisfactory.
In their practical applications the following diffi-culties became particularly apparent:
- the diffusability of the coating composition was insufficient;
- the coating composition had to be applied at least twice;
- the hardened protective coating had only a low elasticity;
- due to strong weathering reworkability of the protective coating was poor;
- with time strong chalking occurred (for this reason the respective directions for those known systems provide for renewal after at least five years);
- the coating composition can only be applied in good, dry weather;
- the finished protective coating exhibits only slight pore sealing;
- the known coal tar/polyurethane-forming isocyan-ate mixtures necessarily have the disadvantages connected with coal tar such as the black color, the bleeding of tar through covering coatings, and the decomposition of coal tar components by W-radiation.
Accordingly it is an object of the present inven-tion to provide a one-component coating composition for the protection of building structures which shows improvements over at least some, preferably all, of the disadvantages of the known systems.
The coating composition according to the in-vention is a one-component coating composition which hardens under exposure to moisture and which comprises:
15 to 70% by weight polyurethane-forming iso-cyanate, 5 to 25~ by weight light-liquid, OH-grou~s-con-taining, low molecular, aromatic hydrocarbon resin, 0.2 to 2% by weight anti-settling agent, 10 to 35% by weight flake-shaped extender, 2 to 25% by weight coloring pigment, 1 to 5~ by weight moisture-absorbing agent, and the remainder,at least however 5% by weight,resin solvent.
In contrast to the known coal tar the hydrocarbon resin according to the invention is a colorless or lightly yellow oil so that the inventive composition results in a clear and light, even white, coating which nevertheless exhibits the advantageous properties of the polyurethane/coal tar coating. When exposed to the sunlight, the light coatings according to the invention compose, due to UV-radiation, to a lesser extend than the known coal tar containing coatings.
Moreover, it is an object of the present invention to provide a method of producing a protective coating by applying the inventive one-ccmponent coating composition to a clean base and allowing the composition to harden under exposure to moisture in the surrounding atmos-phere.
Due to the fact that the inventive coating compo-sition is a one-com~onent system, the composition can,on exclusion of moisture, be stored for substantially ,~P .~ i' ~25~034 unlimited time while hardening w-ithin about lO to 30 minutes after application to a base a~d on expos~re bo moisture in the surrounding atmosphere so that, if desired, already after about 30 minutes one or more additional coating(s) can be applied. After about 15 to 20 hours the total protective coating is completely hardened and can be exposed to the intended load.
The coating composition according to the invention is suited for producing protective coatings for the protection of building structures in general. Preferred applications include the protection of roofs of all kinds including the sealing of flat roofs covered with tar board or tar paper, the coating of concrete and the corrosion protection of steel concrete.
Further object and advantages of the invention will become apparent from the following description and claims.
In the following the advantages and characteris-tics of the coating composition according to the invention are listed in abbreviated form:
- the coating composition is still workable at temperatures of less than 5C;
- the coating composition is workable even at relatively high atmospheric humidity, for example, at humidities of more than 90~;
- the coating composition is self-spreading;
- the coating produced with the coating composi-tion affords excellent protection against ultrava let radiation;
- the finished protective coat exhibits good reflection values in respect of radiation of light and heat;
- even when the protective coat is thin, for ex-ample in the magnitude of only 50 ym, the finished coat exhibits high pore sealing;
~257034 - the finished protecti~e coat shows good elasticity and high adhesive strengths - even after weather~ng the protective coat is reworkable without problem;
- prior to application of the coating composition only the usual simple pre-treatme~t of the base is required;
- the protective coat is flame-resistant; and - even when the protective coat is thick, for example thicker than 200 ~m, no cracking of the coat occurs during hardening.
In the following the invention is described in more detail with reference to preferred embodiments.
The coating composition according to the inven-tion comprises the following ingredients in the given proportions:
15 to 70% by weight polyurethane-forming iso-cyanate;
5 to 25% by weight light, liquid, OH-groups-c~n-taining, low molecular, aromatic hydrocarbon resin;
0.2 to 2% by weight anti-settling agent;
10 to 35% by weight flake-shaped extender;
2 to 25% by weight coloring pigments;
1 to 5% by weight moisture absorbing agent; and at least 5% by weight resin solvent.
In addition to the listed nec~ssary ingredients the coating composition according to the invention can contain additives and supplements commonly used in the resin, varnish, lac~uer or related technologies such as, anti-bacterial or anti-fungal agents, additives inhibit-ing decomposition ~y light, heat and/or corrosive influences, and other commonly used additives adapted for specific requirements (for example to suppress blister formation) or anti-drip agents.
12570~4 - 6 .
As pol~ureth~ne~forming isocyanates kno~n di-~
isocyanates, triisocyanates and low ~olecular poly isocyanatesmay be used such as, for ex~le, the grouP of ~socyanates available under the trademark "Desmodur".
Good results were obtained with toluylene diisocyanates, whereby 2,4- as well as 2,6- toluylene diisocvanate or the commercially available isomer mixture may be used.
Furthe~more, diphenylmethane-4,4'-diisocyanate or hexamethylene-1,6-diisocyanate can be used as poly-urethane-forming isocyanate.
As further essential ingredients the coating composition according to the invention contains a liquid OH-groups-containing aromatic hydrocarbon resin.
In contrast to the known tar, in particular, coal tar, the hydrocarbon resin according to the invention is a light, i.e. colorless to light yellow, material with a brightness according to Barrett of between about 0.5 and 2.
The hydrocarbon res;n is liquid and has at 25C
a viscosity of between about 700 and 2,000 cP.
The resin is a low molecular, aromatic material with a~ average molecular weight of 600. The density of the hydrocarbon resin at 20C is between about 1 and 1.2 g/cm3.
The acid number of the hydrocarbon resin is preferably between about 0.2 and 3.
The hydrocarbon resin necessarily contains a certain portion of OH-groups. Preferably, these are aromatic OH-groups which result from a prior "phenol modification" or "activation". Preferably, the hydrocarbon resin contains OH-groups,particularly aromatic OH-groups, in an amount of about 2 to 4%
by weight of the resin.
The hydrocarbon resin is preferably free of water and solvents. The amount of volatile components in the hydrocarbon resin ~s less than~l0% and can in certain commercially available products be between about ~25~03~
~ 7 -5 and ~% by wei~ht.
Hydrocarbon resins of this kind are known in the art and are offered by commerc~al establ~shments specifically for the requirements of the resin and related industries. To descri~e these materials terms such as special light resistant tar", "Albino-tar" etc. are used in the art. For example, materials available under the tradèmark "aktivierte VFT Spezial-Flussigharze" from VFT-Vertriebsgesellschaft fur Teererzeugnisse mbH, Essen,Federal R~Iblic o~ G~Eny, may be used as hydrocarbon resin according to the invention.
Anti-settling agentsfor the present kind of coating compositions are known in the art. Known anti-settling agents which are useful according to the invention include, for example,montmorillonite, silica, hydrogenated castor oil and the like.
Flake-shaped extenders or fillers are also known. Flake-shaped extenders which are useful ac-cording to the invention include, for example, talc,barium sulphate, flaked pigments based on Si/Al-oxides and similar filler materials. The extenders according to the invention should contain little or, preferably, no carbonate and/or CO2-releasing components so that in admixture with polyisocyanate stability on storage is assured.
Coloring pigments for the present kind of coating compositions are also known. These pigments convey to the protective coat the ability to reflect 3Q light and heat and give the coat a certain color.
Suitable coloring pigments are commercially available, for example, under the trademarks "Sicominp~gment", "Heliogenpi~ment", "Litholpigment" and the like.
According to a further aspect of the invention at least a portion of the "coloring" pigments consists of aluminum powder. Preferably, a flake-shaped alum-~num powder having an area extension of less than 45 ,um ~Z57034 ` 8 .
is used. Prefe~ably, the alum~num component amounts to about 20 to 80~ hy weight of the coloring pigment.
In a particularly preferred embodiment the coating composition contains about 1 to 6~ aluminum pigment relative to the total weight of the coating composition.
Su~table moisture-absorbing or mois~ure-extracting agents include finely divided natural and synthetic zeolites (for example "Zeolith l-Paste" (trademark) available from Bayer AG), and molecular sieves made of alumina and silica compounds, which may be supplemented with titanium. Moreover, agents which bind or absorb water chemically such as monoisocyanate can also be employed. Such moisture-binding, moisture-absorbent or moisture-extracting agents are also commercially available.
As resinsolvents the known solvents and solvent mixtures are suitable. For example, ~ommonly available mixtures of aromatics with a molecular weight of between 100 and 200 proved useful. Furthermore, solvents commonly used in the resin industry based on aliphatic esters such as acetates, propionates and/or butylates can be employed. Higher esters are less suitable, because the resulting drying time may be too long.
The preparation of the coating composition according to the invention can be effected according to techniques commonly used in the resin industry.
Generally, the ingredients are placed into a vessel in the required proportions and mixed with a speed stirrer or dissolver. It proved useful to place a mixture of polyurethane-forming isocyanate and hydro-carbon resin into the vessel and then successively add the other ingredients, whereby the moisture-ab-sorbing agent is added last. Stirring for a period of 10 to 20 minutes at room temperature was found to give satisfactory results. A slight rise in tempera-ture, for example up to about 40C, may occur. This is probably not attributable to any reaction heat, but ~2S~034 to shearing forces. Finally, the re~uired amount of solvent is added to ensure workability of the material.
Following this the material is again mixed for a short period yielding a self-spreading, structurally viscous composition which is ready for use.
If required, the coating composition can be stored. The storage stability at room temperature is at least 6 months. Individual samples were stored for more than 12 months without noticable increase in viscosity and/or decrease in reactivity.
Since the coating composition according to the invention is a one-component system, no pot time worth mentioning is given. After opening of the storage container the composition should be applied speedily otherwise film formation and slow through-reaction takes place due to the presence of atmospheric moisture.
Application of the coating composition to the intended base can be effected according to conventional methods such as by way of a roller or by spraying.
For example, the Airles (trademark) spraying method which employs high pressure was found useful.
The coating composition is applied to the provided base in a thickness of at least 20,um. Pre-ferably the thickness of the coating is between about 50 and 70Jum. It is also possible to apply several coats, each new coat being applied after each previously applied coat has substantially hardened. For example, a coat which is 45~m thick dries at the ambient conditions within about 15 minutes and is reworkable after about 30 minutes so that one or more additional coat(s) can be applied.
After about 18 hours the protective coating is com-pletely hardened and firm and can be exposed to the intended load. After weathering and/or aging of the resulting protective coating,even over a period of one year or longer, this coating can,without difficulty, again be coated with the same inventive coating composition.
i , . ..
~s lQ ~
The preparation of the hase does not call for special measures. It is sufficient if the base is free of dirt and dust as can be ach~eved by s~mple sweeping. No special requirements regarding the dry-ness of the base has to be met. The coating compositionaccording to the invention can be applied to a moist, but not quite wet area without effecting either the hardening and setting or the quality of the finished protective coating.
After application of the coating composition to the base,the composition hardens by itself under the influence of the moisture in the surrounding atmos-phere without necessitating any special measures.
According to a further aspect of the invention there is provided a one-ol~onent composition which hardens under exposure to moisture and which within the framework of the above described composition contains a relatively small amount of polyurethane-forming isocyanate. Preferably, this specific coating composition comprises:
15 to 40% by weight polyurethane-forming isocyanate;
5 to 25% by weight of the above described hydrocarbon resin;
0.5 to 2% by weight anti-settling agent;
15 to 35~ by weight flake-shaped extender;
5 to 25% by weight coloring pigments;
1 to 5% by weight moisture-absorbing agent; and the remainder, at least however 5% by weight, ~ mon resin solvent.
In this embodiment, too, the coloring plgments contain a certain portion of aluminum powder. Prefer-ably, the portion of aluminum powder amounts to between 20 and 80% by weight of the coloring pigment. In a particularly preferred embodiment the amount of poly-urethane-forming isocyanate is 15 to 30% of the total weight of the coating composition. Toluylene di-, ~2s7a34 --` 11 ~`
isocyanate containing isocyanate groups in an amount of about 5.5 to 7.5% of the t~tal weight of isocyanate is preferred as polyurethane-forming ;socyanate for this embodiment.
This "reIatively isocyanate-poor" embodiment of the invention is well suited for the protection of building structures due to its good elasticity, its high adhesive strength on various materials and due to its resistance to UV-radiation. This embodiment is particularly suitable for the protection of roofs of all kinds such as, for example, Eternit (trademark) roofs, roofs insulated with PU-Hartschaum (trademark) and the like. A further application in the art of roofs is the foam coating, namely, the roof foam coating of so-called reverse roofs. Moreover, this particular coating composition is suitable as protect-ive coating for engineering constructions, industrial and energy construction, steel construction, ship construction, off-shore construction and the like.
If this particular coating composition is used to coat steel, prior sand blasting (Sa 2.5) is recommended.
To achieve especially good corrosion protection the application of the coating composition may be preceded by priming. Moreover, this particular coating com-position is suitable for the protection of concrete and for the corrosion protection of steel concrete.
In all cases excellent resistance to radiation, light, heat and/or corrosion influences is achieved.
A further specific embodiment of the invention contains within the framework of the above described composition a relatively high portion of polyurethane-forming isocyanate. Preferably, this specific coating composition comprises:
40 to 70% by weight polyurethane-forming isocyanate;
5 to 25~ by weight hydrocarbon resin;
0.2 to 1% by weight anti-settling agent;
~ ~5703~i ~ 12 .
10 to 20~ by weight flake-shaped extendex;
2 to 15% by ~eight coloring pigments;
1 to 4~ by weight moisture-absorbing agent; and the remainder, at least however 5%by weight, resin solvent.
In the coating composition according to this particular embodiment at least a portion of the color-ing pigment consists of aluminum powder. Preferably the portion of aluminum powder amounts to 20 to 80% of the total weight of the coloring pigments.
This"relatively isocyanate-rich" coating compo-sition contains as polyurethane-forming isocyanate preferably diphenylmethane diisocyanate, especially a diphenylmethane diisocyanate containing isocyanate groups in an amount of 9 to 12% of the weight of the isocyanate. Particularly preferred is a mixture of different diphenylmethane diisocyanates which differ in their isocyanate content. In this respect good results were obta~dwhen the total amount of 40 to 70~
by weight of polyurethane-forming isocyanate (relative to the total weight of the coating composition) con-sists of a) 30 to 50% by weight diphenylmethane diiso-cyanate containing isocyanate groups in an amount of 8 to 9% of the total weight of isocyanate; and b) 10 to 20~ by weight diphenylmethane diiso-cyanate containing isocyanate groups in an amount of 14 to 17% of ~he tota~ weight of isocyanate.
Such a relatively isocyanate-rich coating com-position containing different diphenylmethane diiso-cyanate yields after exposure to moisture a lightly foaming coating. The latter has a joint-sealing effect, particularly in coating and sealing of roofs which are covered with tar board. In spite of this foam formation the resulting film is highly pore-sealing and water-impervious. This particular coating composition is workable at air temperatures o~ from 5 to 40~C and also at high atmospheric moisture, for example at a relative humidity of over 90~. This coating composition isi on the one hand,self-spreading and can, on the other hand, ~e applied in thick layers so that, for example, in one application coats having a thickness of up to 200 ~m or more can be achieved.
On hardening the composition forms a lightly foaming film which evens out roughness of the base and which seals the joints. The coating resulting from this particular coating composition also exhibits high pore-sealing, high elasticity and high adhesive strength.
In view of the preferred application of this particular coating composition for the sealing of flat roofs covered with tar board this coating composition pre-ferably contains resin solvents based on aliphatic esters such as acetates, propionates and/or butylates so as to avoid partial and/or complete dissolving of the tar-constituents in the tar board by aromatic solvent components.
This particular coating composition can be applied in one step up to a thickness of 1000 ,um without encountering adhesivity problems or the like.
As previously indicated, this particular coating composition is especially adapted to seal flat roofs covered with tar board. To this effect the coating composition is applied with a thickness of at least 50 ,um. Preferably, at least 500 g coating composition are applied per s~uare meter of tar board. Due to the light foam formation which occurs on hardening this coating composition enters joints, overlapping areas and border areas of the tar board sheets and provides sealing of joints which lasts for many years.
Claims (15)
1. Moisture-setting single-component coating composition, comprising from about:
15 to 70 wt.-% polyurethane-forming isocyanate, 5 to 25 wt.-% light-colored, liquid, aromatic hydrocarbon resin, brightness according to Barrett of between about 0.5 to 2, of low molecular weight containing hydroxyl groups, 0.2 to 2 wt.-% antisettling agents, 10 to 35 wt.-% flake-shaped extender, 2 to 25 wt.-% tinting pigment, 1 to 5 wt.-% moisture-binding agent, balance, but not less than 5% by weight, of conventional paint solvent.
15 to 70 wt.-% polyurethane-forming isocyanate, 5 to 25 wt.-% light-colored, liquid, aromatic hydrocarbon resin, brightness according to Barrett of between about 0.5 to 2, of low molecular weight containing hydroxyl groups, 0.2 to 2 wt.-% antisettling agents, 10 to 35 wt.-% flake-shaped extender, 2 to 25 wt.-% tinting pigment, 1 to 5 wt.-% moisture-binding agent, balance, but not less than 5% by weight, of conventional paint solvent.
2. Moisture-setting single-component coating composition for the protection of buildings, comprising from about:
15 to 40 wt.-% polyurethane-forming isocyanate, 5 to 25 wt.-% light-colored, liquid, aromatic hydrocarbon resin, brightness according to Barrett of between about 0.5 to 2, of low molecular weight containing hydroxyl groups, 0.5 to 2 wt.-% antisettling agents, 15 to 35 wt.-% flake-shaped extender, 5 to 25 wt.-% tinting pigments, 1 to 5 wt.-% moisture-binding agent, balance, but at least 5% by weight, of conventional paint solvent.
15 to 40 wt.-% polyurethane-forming isocyanate, 5 to 25 wt.-% light-colored, liquid, aromatic hydrocarbon resin, brightness according to Barrett of between about 0.5 to 2, of low molecular weight containing hydroxyl groups, 0.5 to 2 wt.-% antisettling agents, 15 to 35 wt.-% flake-shaped extender, 5 to 25 wt.-% tinting pigments, 1 to 5 wt.-% moisture-binding agent, balance, but at least 5% by weight, of conventional paint solvent.
3. Single-component coating composition of Claim 2, wherein the content of polyurethane-forming isocyanate amounts to 15 to 30% of the total weight of the coating composition.
4. Single-component coating composition of Claim 1 or Claim 3, wherein the polyurethane-forming isocyanate has a content of isocyanate groups of 5.5 to 7.5% with respect to the isocyanate weight.
5. Single-component coating composition of Claim 2, wherein the polyurethane-forming isocyanate is a toluylene diisocyanate, or a mixture of different toluylene diisocyanate isomers.
6. Single-component coating composition of Claim 2, wherein the paint solvent is a mixture of aromatic hydrocarbons.
7. Moisture-setting single-component coating composition for sealing flat roofs covered with roofing felt, comprising from about:
40 to 70 wt.-% polyurethane-forming isocyanate, 5 to 25 wt.-% light-colored, liquid, aromatic hydrocarbon resin, brightness according to Barrett of between about 0.5 to 2, of low molecular weight containing hydroxyl groups, 0.2 to 1 wt.-% antisettling agent, 10 to 20 wt.-% flake-shaped extender, 2 to 15 wt.-% tinting pigments, 1 to 4 wt.-% moisture-binding agent, balance, but no less than 5% by weight, of paint solvent.
40 to 70 wt.-% polyurethane-forming isocyanate, 5 to 25 wt.-% light-colored, liquid, aromatic hydrocarbon resin, brightness according to Barrett of between about 0.5 to 2, of low molecular weight containing hydroxyl groups, 0.2 to 1 wt.-% antisettling agent, 10 to 20 wt.-% flake-shaped extender, 2 to 15 wt.-% tinting pigments, 1 to 4 wt.-% moisture-binding agent, balance, but no less than 5% by weight, of paint solvent.
8. Single-component coating composition of Claim 7, wherein the polyurethane-forming isocyanate has an isocyanate group content of 9 to 12% of the isocyanate weight.
9. Single-component coating composition of Claim 7 or Claim 8, wherein the polyurethane-forming isocyanate is diphenylmethane diisocyanate.
10. Single-component coating composition of Claim 7, wherein the total content of 40 to 70 wt.-%
polyurethane-forming isocyanate - with respect to the total weight of the coating composition - comprises from about:
(a) 30 to 50 wt.-% of diphenylmethane diisocyanate having an isocyanate group content of 8 to 9%, with respect to the isocyanate weight, and (b) 10 to 20 wt.-% of diphenylmethane diisocyanate with an isocyanate group content of 14 to 17% of the isocyanate weight.
polyurethane-forming isocyanate - with respect to the total weight of the coating composition - comprises from about:
(a) 30 to 50 wt.-% of diphenylmethane diisocyanate having an isocyanate group content of 8 to 9%, with respect to the isocyanate weight, and (b) 10 to 20 wt.-% of diphenylmethane diisocyanate with an isocyanate group content of 14 to 17% of the isocyanate weight.
11. Single-component coating composition of Claim 7, wherein aliphatic hydrocarbons of a molecular weight of about 100 to 150, containing ester groups, serve as lacquer and varnish solvents.
12. Single-component coating composition of Claim 1, wherein the hydrocarbon resin -- with respect to the resin weight -- has a hydroxyl group content of 2 to 4%.
13. Single-component coating composition of Claim 1, wherein the hydrocarbon resin has at 25°C a viscosity of 700 to 2000 cP.
14. Single-component coating composition of Claim 1, wherein the hydrocarbon resin has at 20°C a density between 1.02 and 1.2 grams per cubic centimeter.
15. Single-component coating composition of claim 1, wherein a part of the tinting pigment, namely 20 to 80% of the total pigment weight, consists of aluminum powder.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000438512A CA1257034A (en) | 1983-10-06 | 1983-10-06 | One-component coating composition and method of producing a protective coating |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000438512A CA1257034A (en) | 1983-10-06 | 1983-10-06 | One-component coating composition and method of producing a protective coating |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1257034A true CA1257034A (en) | 1989-07-04 |
Family
ID=4126238
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000438512A Expired CA1257034A (en) | 1983-10-06 | 1983-10-06 | One-component coating composition and method of producing a protective coating |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1257034A (en) |
-
1983
- 1983-10-06 CA CA000438512A patent/CA1257034A/en not_active Expired
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