NL2028611B1

NL2028611B1 - Elastic polymer coating composition for coating of a wall or ceiling surface

Info

Publication number: NL2028611B1
Application number: NL2028611A
Authority: NL
Inventors: Kouwenhoven Dirk
Original assignee: Sinck&Ko B V
Priority date: 2021-07-02
Filing date: 2021-07-02
Publication date: 2023-01-10
Also published as: EP4363470A1; WO2023275319A1

Abstract

present invention relates to a composition for providing a wall and/or ceiling With an elastic polymer coating composition that free of solvent. The present invention further relates to a method for providing a wall and/or ceiling With a coating of elastic composition that is 5 flexible, resistant to cracking and durable.

Description

ELASTIC POLYMER COATING COMPOSITION FOR COATING OF A WALL OR

CEILING SURFACE Description The present invention relates to a composition for providing a wall and/or ceiling with an elastic polymer coating composition. The present invention further relates to a method for providing a wall and/or ceiling with a coating of elastic composition.

Wall or ceiling plaster is the most common form of interior finishing, next to wall paper and ordinary paint. These plaster compositions that are generally rough and not smooth, and are prone to breakage or cracking over time (dying out and aging effect). At first instance, a plaster coating creates a strong and wall finish due to the chemical reaction that occurs when water evaporates out of the plaster mixture. However, over time the plaster becomes less resistant to knocks and dents. Plaster is continually curing becoming harder which makes it more brittle over time. Furthermore, due to its complete inflexibility of the plaster and in case of small shifting foundations or a strong blow or vibrations (i.e. high traffic) to the wall or ceiling surface, the plaster cracks or crumbles which are difficult to repair. Damaged plaster must be cut and scraped out without damaging the intact wall material.

Plaster also changes colour slightly as it ages, resulting in small changes in colour and patches of wall that stand out and need repair or further coating, such as paint. In addition, it can take up to a month for a plaster wall to cure fully enough, depending on the thickness of the applied layer, to allow for painting which can slow down the construction process.

Coinciding with the durability of the plaster, a drawback is the look and feel of the surfaces comprising plaster; these surfaces are often hard, irregular and result in that the coating has a tendency to attract air born dust and dirt and to stick to the surface, making the surface more difficult to clean. A drawback when using the plaster on a wall and/or ceiling have an open cell or porous structure, that is that it is difficult to achieve a smooth and durable coating. When coating a wall and/or ceiling with plaster, the porous cellular structure of the material will providing an irregular coated surface that is not uniform in thickness and density. Finishing the wall or ceiling with plaster as such to provide a smooth surface, takes multiple days because the seams between boards of most ceilings or walls needs to dry before another coat can be added providing a smooth finish.

Considering the above, there is a need in the art for a wall or ceiling coating providing a protective and more durable coating that retains the advantageous physical, i.e. protective and durability properties of a plaster, and furthermore provides a wall finish that is completely seamless, waterproof, and has improved elastic properties and reduced tendency to attract dust and dirt. The coating should improve in durability (resistant to denting, breakage or cracking) over time and provide at the same time an improved tactility of the wall and/or ceiling being coated, i.e. softer look and feel as compared to for example plaster.

It is an object of the present invention, amongst other objects, to address the above need in the art. The object of present invention, amongst other objects, is met by the present invention as outlined in the appended claims.

Specifically, the above object, amongst other objects, is met, according to a first aspect, by the present invention by An elastic polymer coating composition for coating of a wall and/or ceiling surface, wherein said composition is free of solvent and is comprised of between 20 - 30 wt%, preferably 24 to 28 wt% caster oil based hydroxyl polyol, 4 - 10 wt%, preferably 6 to § wit% polyether polyol having a molecular weight of at least 450 MW, 17 — 25wt%, preferably 19 to 22 wt% isocyanate, 32 - 45 wt%, preferably 35 to 39 wt% filler, 1.5 -4 wt% molecular sieve agent, 0.01 - 0.1 wt% organometallic- or dioctyltin mercaptide based catalyst, based on the total weight of the elastic polymer coating composition, wherein said composition, when polymerized as coating on a wall and/or ceiling surface, has a Young's modulus elasticity as determined by ASTM D638 of at least 80 MPa, preferably at least 100 MPa. 4 - 10 wt, glycerol The composition of present invention provides an elastic wall or ceiling finish on the coated surfaces. In contrast to the mineral plaster coatings, the composition of present invention is durable, provides high resistance to cracking and denting due to its flexible properties, is fully resistant to moisture (100% waterproof), UV resistant and does not fade significantly in colour over time. Furthermore, due to a closed cell structure the provided finish of the composition of present invention on a surface does not attract dust and dirt, such as on a coated wall, ceiling or floor. When coated on a wall or ceiling surface the composition will polymerize providing a solid coating. Due to the molecular weight of at least 450 MW of the polyether polyol, the coating composition of present invention will undergo elastic deformation when a small load or pressure (i.e. as occurs with plaster leading to denting or cracking) is applied to it in compression or extension. However, with the coating composition of present invention, elastic deformation is reversible and the material returns to its original shape after the load is removed, due to the elastic properties of the composition. The composition of present invention, when polymerized as coating on a wall and/or ceiling surface, has a displacement of at least 8 mm without leading to breakage or cracking of the coating composition at a tensile force exerted of 40 N, and has a critical engineering stress {MPa) at the breaking point of at least 1.2 MPa, preferably at least 1.5 MPa, as determined by ASTM D638 in a tensile strength test.

The composition, when coated and fully cured on a wall or ceiling surface is closed cell structure, with no pores where dust and dirt can accumulate, as occurs with plaster. Due to the reduced porosity and improved smoothness air born dust and other small debris will not tend to stick to coated surface of the wall and/or ceiling. Furthermore, surfaces being provided with the composition of present invention are easy to clean. The coating composition provides improved tactility of the coated wall surface, i.e. has improved look and feel of a material and determines how the sensation is of the person who touches the material. Especially tangible physical properties of a material such as smoothness, flexibility, softness and heat play a role in the improved tactility due to the elastic polymer coating composition of present invention. A wall and/or ceiling coated with the composition of present invention provides the wall and/or ceiling with a soft touch, and a warm look and feel, the a wall and/or ceiling does not feel rough and hard, as other plasters or wall covering materials do.

According to a preferred embodiment, the present invention relates to the elastic IO polymer coating composition, wherein the caster oil based hydroxyl polyol has a viscosity of 700- 1000 cPs. Castor oil based natural polyols are hydroxyl (OH-) functional polyols based on castor oil and are based on renewable raw materials having a viscosity specification range of 700-1000 cPs. Too low viscocity will make the composition unsuitable to apply to a wall as coating and will drip, too high viscosity will also hamper application to the wall and to provide an even finish.

According to another preferred embodiment, the present invention relates to the elastic polymer coating composition, wherein the polyether polyol is glycerol propoxylated polyether triol. Compositions with glycerol propoxylated polyether triol provided the most optimal composition providing a wall finish that is completely seamless, waterproof, and has improved elastic properties and reduced tendency to attract dust and dirt.

According to yet another preferred embodiment, the present invention relates to the elastic polymer coating composition, wherein the filler is one or more selected from the group consisting of calcium carbonate, magnesium carbonate, calcium magnesium carbonate, silica and quartz, preferably magnesium carbonate or calcium carbonate.

According to another preferred embodiment, the present invention relates to the elastic polymer coating composition, wherein the organometallic or dioctyltin mercaptide based catalyst is selected from the group consisting of dioctyltin dithioglycolate, titanium trichloride, and triethylaluminum, preferably dioctyltin dithioglycolate. Multiple organometallic catalysts are suitable in the composition of present invention, such as titanium trichloride, triethylalaminum or organotin carboxylate catalysts. Most preferred is dioctyltin dithioglycolate, a catalyst based on dioctyltin mercaptide. This provides a higher hydrolytic stability than the organotin carboxylate catalysts. Furthermore, dioctyltin dithioglycolate has a short shelf life and provides faster curing times.

According to yet another preferred embodiment, the present invention relates to the elastic polymer coating composition, wherein the molecular sieve agent is a crystalline metal aluminosilicates. Crystalline metal aluminosilicates have a relatively high contact surface area and a uniform pore distribution that have been activated for adsorption by removing their water of hydration. Unlike other adsorbents, Crystalline metal aluminosilicates have a precise uniform size and molecular dimension, providing the most optimal removal of gases and liquids (mainly water) from the composition of present invention during polymerization, when applied on the wall or ceiling surfaces. The molecular sieve is used in combination with the anti foaming agent for solvent-free coating of present invention to obtain a clear air free formulation.

According to a preferred embodiment, the present invention relates to the elastic polymer coating composition, wherein the composition further comprises 1 - 2 wt% anti foaming agent.

According to a preferred embodiment, the present invention relates to the elastic polymer coating composition, wherein the composition further comprises between 2 - 6 wt%, preferably 3 - 4 wt% of a thickening or thixotropic agent selected from the group consisting of polyethylene based thickener, polyurethane based thickener, and organically modified phyllosilicate. Thickeners are not only used to increase the viscosity and provide a stable viscosity of the composition, but also to adjust their rheological profiles and flow behaviour of the composition, required for a proper application processes and optimal coating of the wall or ceiling, e.g. for thick layer applications. In many cases it is desirable for the elastic polymer coating composition of present invention to flow sufficiently to form a uniform layer (coating), then to resist further flow, thereby preventing sagging on a vertical surface. Also the viscosity of the composition should be such that it is able to adhere to the wall or ceiling that is coated. A thixotropic agent can increase the viscosity and reduce the flowability of the composition without adversely affect the physical properties of the elastic composition, when cured. Preferably the thixotropic agent is based on a laminar silicate that, once it has been dispersed and evenly distributed in the composition of present invention interact and form a structure similar to that of a house of cards, resulting in a gelling effect of the composition.

According to another preferred embodiment, the present invention relates to the elastic polymer coating composition, wherein the composition further comprises one or more additives, such as a pigment.

The present invention, according to a second aspect, relates to a method for providing a wall and/or ceiling with an elastic polymer coating composition, wherein the method comprises the steps of a) providing a composition of any one of claims 1-8 on the surface of the a wall and/or ceiling, thereby coating the surface of the a wall and/or ceiling with a layer of elastic polymer coating composition, b) allowing polymerization of the composition, and optionally c) providing at least a further layer of said composition to form a further layer of elastic polymer coating composition coating on said a wall and/or ceiling. When the first layer is allowed to cure, adherence of the first layer of (basis) 5 composition to the a wall and/or ceiling (e.g. a foam a wall and/or ceiling) is provided by mechanical binding to the a wall and/or ceiling. The elastic polymer coating composition is allowed to polymerize, although not fully cured. For optimal adhesion of the at least further layer of coating, said layer is preferably provided on the first {or preceding) layer within the gel time of the composition of the first layer. Polymerization time depends on various conditions, such as IO temperature of the surrounding air of the wall and/or ceiling, and humidity, and can be influenced by the addition of additives or the presence of impurities in the liquid composition mixture. The first layer can provide an optimal basis of further coating of the wall and/or ceiling. The method of present invention provides a wall and/or ceiling with a coating of elastic composition that is durable, provides high resistance to cracking and denting due to its flexible properties, is fully resistant to moisture (100% waterproof) and does not fade significantly in colour over time.

According to a preferred embodiment, the present invention relates to the method for providing a wall and/or ceiling with an elastic polymer coating composition, wherein said layer of elastic polymer coating composition has a thickness of between 0.2 - 5 mm, preferably 1 -3 mm. In case the layer of elastic polymer coating composition exceeds the indicated thickness, the coating is likely to drip off or flow down over the surface providing a less clean finish or coated surface area. In case the layer of elastic polymer coating becomes too thin, the Young's modulus elasticity and the force at breaking point decrease.

According to another preferred embodiment, the present invention relates to the method for providing a wall and/or ceiling with an elastic polymer coating composition, wherein polymerization is allowed for at least four hours, preferably at least six hours, more preferably at least eight hours, most preferably at least twelve hours, subsequently followed by application of a further layer said elastic polymer coating composition. For optimal adhesion of a further layer of coating composition, said layer is preferably provided on the first layer after polymerization of the first layer is largely completed, i.e. after at least 4 hours after application of the composition of the first layer. For the method of present invention, it is not necessary to await a fully cured first layer in order to proceed with providing the coated a wall and/or ceiling with an additional layer of the elastic polymer coating composition of present invention. When the first layer is fully cured less optimal adhesion of the additional layer is achieved, since the additional layer bind to the first layer via chemical interaction. This chemical interaction is strongly reduced or even absent, when the base layer (first layer) is fully cured in stead of still being in the gel time of the composition of the first layer. Furthermore, small repairs can easily and quickly be done to guarantee a 100%

waterproof coating of the surface. Known plasters for ceiling or wall coating require at least 24 to 72 hours before additional layers can be further applied to the coated surface comprising a first layer of plaster.

The present invention will be further detailed in the following examples and figures wherein: Figure 1: The mechanical properties of a composition of present invention is tested in a tensile strength test. Figure 1 shows mechanical test results on the tensile strength (tensile carves) of the sample 1. At a force exerted on the sample of approximately 25 Newton (N) the sample breaks as observed as a loss in exerted force after a displacement of the material of approximately 3.5 mm.

Figure 2: Shows mechanical test results on the tensile strength of sample 2 comprised of the composition of present invention. The maximum force being tested of 50 N could be exerted on the sample 2 without instant breakage as observed with sample 1. After a displacement of approximately 10 mm, and at an exerted force of 40 N, the material of sample 2 breaks.

Figure 3: The composition of present invention, sample 2, is much more resistant to both stress and deformation (strain) when compared to the wall coating composition known in the art, sample 1. Figure 3 shows the difference between the critical engineering stress (MPa) at the breaking point of the two tested samples. Here it shows that the sample 2 comprising the composition of present invention has improved properties being able to cope with 70% higher pressure when compared to sample 1, due to a higher elasticity of the composition compared to known wall/ceiling coating materials.

Figure 4: Shows that the critical strain (deformation) at breaking point is more than a factor of 30 larger for the sample 2 comprising the composition of present invention compared to sample 1, further indicating a high elasticity and durability of the sample 2.

Figure 5: Shows the modulus of elasticity (Young's modulus) in tension (MPa) that measures the tensile stiffness of the sample material. It quantifies the relationship between tensile stress and axial strain in the linear elastic region of the sample material, according to the formula of Young's modulus E.

Example — tensile strength test of the composition A comparative study was performed on the mechanical properties of composite materials for wall covering by the Institute of Physics (Van der Waals-Zeeman Institute) at the University of Amsterdam.

Tensile specimens were created to perform tensile tests in silicone molds that allow an easy removal of the test sample. The samples are removed from its mold after curing. Briefly, two different test samples were produced having identical dimensions of 6mm(h) x 4mm{w) x 30mm (1). Test sample 1 is comprised of commonly used cement based plaster (Leef beton of Romar Voss) used for coating of ceiling and wall surfaces that was mixed with an acrylic resin dispersion in a ration 5:1 providing a mineral wall or ceiling finish. Test sample 2 is a composition according to present invention is comprised of 27 wt% caster oil based hydroxyl polyol, 7wt% glycerol propoxylated polyether triol, 20 wt% isocyanate, 38.5 wt% filler (Microdol), and 1.5 wt% anti foaming agent (Airex), 2.7 wt% molecular sieve agent (UOP), 0.015 wt% organometallic catalyst (TIB kat). Both test samples were mixed to a homogenous mixture and left to set and dry for at 8 days. Test sample 2 was fully chemically cured.

Next both tests sample are used in the tensile strength test to test the consolidation of the treated samples. A Zwick- Roell tensile testing machine working for tensile and compression tests is used. All the specimens are tested with a speed of J.1 mm/min up to a maximal strength of 50 N. The tests samples were included in specifically manufactured plastic molds to match with the ends of the tensile specimen without stressing them, such to avoid breakage during the clamping in the vices of the testing machine. The testing machine is connected to a computer which records the position of movable end of the sample and the force exerted on the sensor. Knowing the sample dimensions, the tensile curve (engineering stress vs. extension) of the sample was determined.

From the data and the resulting curves {figure 1 and 2) three important parameters are the Young modulus elasticity (slope of the curve) and the critical stress and strain (measured strain when the sample breaks) were determined {figure 3 to figure 5). This experiment was done for 5 samples each.

The composition of present invention, sample 2, is much more resistant to both stress and deformation when compared to the wall coating composition known in the art, sample 1. The critical stress at breaking and the critical strain at breaking are much higher for sample 2 as compared to sample 1. Notably the critical strain is more than a factor of 30 larger for the sample comprising the composition of present invention. This composition of present invention provides a coating that improves the look and feel of the a wall and/or ceiling i.e. uniform coating with soft touch finish, improved elasticity and durability. The composition of present invention is a very suitable wall finish for wet rooms, a wall finish that is completely seamless, waterproof and elastic.

Claims

Conclusions

An elastic polymer coating composition for coating a wall and/or ceiling surface, said composition being free of solvent and comprising between 20 - 30% by weight caster oil based hydroxyl polyol, 4 - 10% by weight polyether polyol having a molecular weight of at least at least 450 MW, 17 - 25 wt% isocyanate, 32 - 45 wt% filler, 1.5 - 4 wt% molecular sieve, 0.01 - 0.1 wt% organometallic or dioctyltin mercaptide based catalyst , based on the total weight of the elastic polymer coating composition, said composition, when polymerized as a coating on a wall and/or ceiling surface, having a Young's modulus of elasticity as determined by ASTM D638 of at least 80 MPa, preferably at least 100 MPa ,

The elastic polymer coating composition according to claim 1, wherein the caster oil based hydroxyl polyol has a viscosity of 700-1000 cPs.

The elastic polymer coating composition of claim 1 or 2, wherein the polyether polyol is glycerol-propoxylated polyethertriol.

An elastic polymer coating composition according to any one of claims 1-3, wherein the filler is one or more selected from the group consisting of calcium carbonate, magnesium carbonate, calcium magnesium carbonate, silica and quartz, preferably magnesium carbonate or calcium carbonate.

An elastic polymer coating composition according to any one of claims 1-4, wherein the organometallic or dioctyltin mercaptide based catalyst is selected from the group consisting of dioctyltin dithioglycolate, titanium trichloride and triethyl aluminum, preferably dioctyltin dithioglycolate.

The elastic polymer coating composition according to any one of claims 1-5, wherein the molecular sieve agent is a crystalline metal aluminum silicate.

The elastic polymer coating composition according to any one of claims 1-6, wherein the composition further comprises 1-2% by weight of an anti-foaming agent.

The elastic polymer coating composition of any one of claims 1-7, wherein the composition further comprises between 2-6% by weight of a thickening or thixotropic agent selected from the group consisting of polyethylene based thickener, polyurethane based thickener and organically modified phyllosilicate.

An elastic polymer coating composition according to any one of claims 1-8, wherein the composition further comprises one or more additives, such as a pigment.

A method for providing a wall and/or ceiling with an elastic polymer coating composition, the method comprising the steps of: a) providing a composition according to any one of claims 1-9 on the surface of the wall and/or the ceiling, thereby coating the surface of the wall and/or ceiling with a low elastic polymer coating composition, b) allowing polymerization of the composition, and optionally c) applying at least one further layer of the composition to achieve a further layer of an elastic polymer coating composition on the wall and/or ceiling.

A method according to claim 10, wherein said low elastic polymer coating composition has a thickness between 0.2 - 5 mm.

A method according to claim 10 or 11, wherein the polymerization is allowed for at least four hours, followed by the application of a further layer of the elastic polymer coating composition.