阅读说明：本技术 多孔建筑材料的涂料组合物 (Coating composition for porous building materials ) 是由 B·C·马 J-P·勒孔特 J·夫约尔凯 S·萨尔瓦蒂 于 2019-09-23 设计创作，主要内容包括：本公开提供水性涂料组合物以涂布多孔建筑材料并且在上面形成膜,以帮助控制所述多孔建筑材料中的风化。所述水性涂料组合物包括粘合剂,其具有：在丙烯酸聚合物水性分散体中的丙烯酸聚合物,其中所述丙烯酸聚合物具有1℃到60℃的玻璃转变温度(Tg)；以及在水性硅烷聚结乳液中的烷氧基硅烷聚结剂。所述水性涂料组合物任选地进一步包括选自由以下组成的群组的添加剂：颜料、填充剂和其组合。在一个实施例中,所述烷氧基硅烷聚结剂为所述水性涂料组合物中的所述丙烯酸聚合物水性分散体提供唯一聚结剂。(The present disclosure provides aqueous coating compositions to coat and form films on porous building materials to help control efflorescence in the porous building materials. The aqueous coating composition includes a binder having: an acrylic polymer in an aqueous acrylic polymer dispersion, wherein the acrylic polymer has a glass transition temperature (Tg) of 1 ℃ to 60 ℃; and an alkoxysilane coalescing agent in the aqueous silane coalescing emulsion. The aqueous coating composition optionally further comprises an additive selected from the group consisting of: pigments, fillers, and combinations thereof. In one embodiment, the alkoxysilane coalescing agent provides the only coalescing agent for the aqueous dispersion of acrylic polymer in the aqueous coating composition.)

1. An aqueous coating composition for porous building materials comprising:

3.5 to 100 weight percent (wt%) of the binder, the binder comprising, on a dry weight basis, based on the total dry weight of binder:

85 to 97% by weight of an acrylic polymer in an aqueous acrylic polymer dispersion,

wherein the acrylic polymer has

A glass transition temperature (Tg) of 1 ℃ to 60 ℃; and

15 to 3 weight percent of an alkoxysilane coalescing agent in the aqueous silane coalescing emulsion; and

96.5 to 0 wt% of an additive selected from the group consisting of: pigments, fillers, and combinations thereof, the weight% of the binder and the additive being based on the total dry weight of the aqueous coating composition.

2. The aqueous coating composition of claim 1, wherein the alkoxysilane coalescing agent provides the only coalescing agent for the aqueous dispersion of acrylic polymer in the aqueous coating composition.

3. The aqueous coating composition of claim 1, wherein 100 wt.% of the binder forms the aqueous coating composition, wherein the weight percentages are based on the total dry weight of the aqueous coating composition.

4. The aqueous coating composition of claim 1, wherein the acrylic polymer in the aqueous acrylic polymer dispersion has a Tg of 25 ℃ to 55 ℃.

5. The aqueous coating composition of claim 1, wherein the alkoxysilane coalescing agent is selected from the group consisting of: r¹Si(OR)₃、(R¹)₂Si(OR)₂And a method of producing the sameIn combination, each R¹Independently selected from an alkyl group having 1 to 20 carbon atoms, a substituted alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or a substituted aryl group having 6 to 20 carbon atoms, and wherein each R is independently selected from an alkyl group having 1 to 6 carbon atoms.

6. The aqueous coating composition of claim 5, wherein the alkoxysilane coalescing agent is R¹Si(OR)₃。

7. The aqueous coating composition of claim 6, wherein R¹Has 8 carbon atoms and R has 2 carbon atoms to provide triethoxy (octyl) silane; or

Wherein R is¹Has 6 carbon atoms and R has 2 carbon atoms to provide triethoxy (hexyl) silane.

8. The aqueous coating composition of any one of claims 1-7, wherein the aqueous acrylic polymer dispersion has an acid content of acid monomers of at most 2 wt.%, based on the dry weight of the acrylic polymer.

9. The aqueous coating composition of any one of claims 1-8, wherein the acrylic polymer of the aqueous acrylic polymer dispersion is formed from a nonionic monomer selected from the group consisting of: methyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, styrene, butyl methacrylate, 2-ethylhexyl acrylate, tert-butyl acrylate, alpha-methylstyrene, vinyl acetate, hexyl acrylate, and combinations thereof.

10. The aqueous coating composition of claim 9, wherein the acrylic polymer of the aqueous acrylic polymer dispersion is formed from a nonionic monomer selected from the group consisting of: methyl methacrylate and butyl acrylate.

11. The aqueous coating composition of claim 9, wherein the acrylic polymer of the aqueous acrylic polymer dispersion is formed from a nonionic monomer selected from the group consisting of: methyl methacrylate and 2-ethylhexyl acrylate.

12. The aqueous coating composition of any one of claims 1-11 having an amount of water sufficient to provide the aqueous coating composition with a solids content of 2 to 70 weight percent, based on the total weight of the aqueous coating composition.

13. A porous building material at least partially coated with a film formed with the aqueous coating composition according to any one of claims 1 to 12.

14. The porous building material of claim 13, wherein the porous building material is an inorganic porous building material.

15. The porous building material of claim 13, wherein the porous building material is an organic porous building material.

Technical Field

The present disclosure relates generally to coating compositions, and more particularly to coating compositions for use with porous building materials.

Background

Porous building materials like cement-based building materials need to be protected against water penetration to prevent problems like corrosion of the reinforcing bars, weathering and structural damage due to freeze-thaw cycles. Efflorescence is a phenomenon which describes the migration and precipitation of salts to the surface of porous building materials, such as concrete, wherein the salts form specks, powdery and/or crystalline deposits. Efflorescence occurs when the absorbed moisture dissolves salts in the porous building material. The salt then migrates to the surface of the porous building material. Once at the surface, the water evaporates and the salt remains on the surface of the porous building material in the form of a white paint.

It is known to reduce efflorescence by reducing water movement in porous building materials. Typically, this can be done by coating or by impregnation with a silicon-based material. The silicone-based impregnation provides protection against invisible water penetration and gives the surface of the porous building material an unmodified appearance. However, it has been observed that silicone-based impregnation solutions are sometimes not effective in preventing efflorescence.

Accordingly, there is a need to protect porous building materials not only to provide protection against water ingress which can lead to freeze-thaw damage, swelling, corrosion, deformation or impaired mechanical properties (as observed for fiber cement boards), but also to prevent observable efflorescence despite effective reduction of water penetration after treatment of the surface with silicone-based water repellents.

Another approach is to use acrylic-based protection in an attempt to reduce water penetration in porous building materials. Acrylic-based protection is based on the formation of a film at the porous building material surface and results in some surface appearance modification. Even without the addition of pigments/fillers to the acrylic, the surface of the porous building material will have a clear visual gloss. For some applications, it is desirable to provide protection to porous building materials so that the appearance of the material is unmodified (i.e., has a "natural appearance") and does not have a visual sheen.

Many acrylic-based protective compositions also require the use of coalescents to aid in film formation. Coalescing agents generally consist of solvents based on alcohols, esters, ketones, and glycol ethers. However, due to environmental concerns, there is a tendency to reduce the use of organic solvents as coalescents in coating compositions.

Accordingly, there is a need in the art to develop new coalescents for use with acrylic-based protective compositions that provide desirable properties, such as aiding acrylic latex film formation, compatibility, and providing water repellency properties to films formed on porous building materials, such as fiber cement roofs/walls and concrete roof tiles.

Disclosure of Invention

The present disclosure provides aqueous coating compositions to coat and subsequently form a film on porous building materials, where the film helps control efflorescence in the porous building materials. The aqueous coating compositions of the present disclosure provide novel coalescents for use with acrylic-based protective compositions that provide desirable properties, such as aiding in acrylic latex film formation, compatibility, and water repellency properties to films formed on porous building materials, such as fiber cement roofs/walls and concrete roof tiles.

As provided herein, the aqueous coating compositions of the present disclosure include a mixture of alkoxysilane coalescent in an aqueous silane coalescent emulsion and acrylic polymer in an aqueous dispersion of acrylic polymer that work synergistically when formed into a film to provide better protection of porous building materials from water penetration than when using standard coalescents such as ethylene glycol monobutyl ether. While not wishing to be bound by theory, it is believed that the alkoxysilane coalescent in the aqueous silane coalescing emulsion acts as a coalescent during the acrylic polymer film forming process to effectively lower the minimum film forming temperature and aid in film formation of the acrylic polymer in the acrylic polymer aqueous dispersion at room temperature with a mechanism similar to the standard coalescent, ethylene glycol monobutyl ether.

For the various embodiments, the aqueous coating composition includes a binder having: an acrylic polymer in an aqueous acrylic polymer dispersion, wherein the acrylic polymer has a glass transition temperature (Tg) of 1 ℃ to 60 ℃; and an alkoxysilane coalescing agent in the aqueous silane coalescing emulsion. The aqueous coating composition optionally further comprises an additive selected from the group consisting of: pigments, fillers, and combinations thereof. For the purposes of this disclosure, it is possible for an alkoxysilane coalescent to provide the only coalescent to the aqueous dispersion of acrylic polymer in an aqueous coating composition.

For the various embodiments, the aqueous coating composition of the present disclosure includes 3.5 to 100 weight percent (wt%) of a binder and 96.5 to 0 wt% of an additive selected from the group consisting of: pigments, fillers, and combinations thereof. The weight% of the binder and additives are based on the total dry weight of the aqueous coating composition. The adhesive comprises 85 to 97 weight percent acrylic polymer in an aqueous dispersion of an acrylic polymer on a dry basis, based on the total dry weight of the adhesive, wherein the acrylic polymer has a glass transition temperature (Tg) of 1 ℃ to 60 ℃; and 15 to 3 weight percent of an alkoxysilane coalescing agent in the aqueous silane coalescing emulsion. For the various embodiments, it is possible for the alkoxysilane coalescent to provide the only coalescent to the aqueous dispersion of acrylic polymer in the aqueous coating composition. Preferably, the Tg of the acrylic polymer in the aqueous acrylic polymer dispersion is from 25 ℃ to 55 ℃. In a particular embodiment, 100 weight percent of the binder forms the aqueous coating composition, with weight percent being based on the total dry weight of the aqueous coating composition.

The aqueous acrylic polymer dispersions used in the various embodiments may also have an acid content of acid monomers of up to 2 weight percent based on the dry weight of the acrylic polymer. For the various embodiments, the acrylic polymer of the acrylic polymer aqueous dispersion is formed from a nonionic monomer selected from the group consisting of: methyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, styrene, butyl methacrylate, 2-ethylhexyl acrylate, tert-butyl acrylate, alpha-methylstyrene, vinyl acetate, hexyl acrylate, and combinations thereof. More specifically, for the various embodiments, the acrylic polymer of the acrylic polymer aqueous dispersion is formed from a nonionic monomer selected from the group consisting of: methyl methacrylate and butyl acrylate. In other embodiments, the acrylic polymer of the aqueous acrylic polymer dispersion is formed from a nonionic monomer selected from the group consisting of: methyl methacrylate and 2-ethylhexyl acrylate.

For the various embodiments, the alkoxysilane coalescing agent is selected from the group consisting of: r¹Si(OR)₃、(R¹)₂Si(OR)₂And combinations thereof, wherein each R¹Independently selected from an alkyl group having 1 to 20 carbon atoms, a substituted alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or a substituted aryl group having 6 to 20 carbon atoms, and wherein each R is independently selected from an alkyl group having 1 to 6 carbon atoms. More specifically, for the various examples, the alkoxysilane coalescing agent is R¹Si(OR)₃. When the alkoxysilane coalescing agent is R¹Si(OR)₃For various embodiments, R¹Has 8 carbon atoms and R has 2 carbon atoms to provide triethoxy (octyl) silane. Or, R¹Has 6 carbon atoms and R has 2 carbon atoms to provide triethoxy (hexyl) silane.

For the various embodiments, an aqueous coating composition as provided herein can have an amount of water sufficient to provide the aqueous coating composition with a solids content of 2 to 70 weight percent, based on the total weight of the aqueous coating composition. The aqueous coating compositions of the present disclosure can be used to form a film on porous building materials. In particular, the present disclosure includes porous building materials at least partially coated with a membrane formed with an aqueous coating composition as provided herein. Examples of porous building materials include inorganic porous building materials. Other examples of porous building materials include organic porous building materials.

Drawings

Fig. 1A-1H provide film forming speckle rate kinetic curves for comparative examples and example waterborne coating compositions of the present disclosure.

Fig. 2A-2B illustrate water absorption as a function of contact time with a substrate coated with the aqueous coating compositions of comparative examples and examples of the present disclosure.

Detailed Description

The present disclosure provides aqueous coating compositions to coat and subsequently form a film on porous building materials, where the film helps control efflorescence in the porous building materials. The aqueous coating compositions of the present disclosure provide novel coalescents for use with acrylic-based protective compositions that provide desirable properties, such as aiding in acrylic latex film formation, compatibility, and water repellency properties to films formed on porous building materials, such as fiber cement roofs/walls and concrete roof tiles.

As provided herein, the aqueous coating compositions of the present disclosure include a mixture of an alkoxysilane coalescent in an aqueous silane coalescing emulsion and an acrylic polymer in an aqueous dispersion of acrylic polymer that, when formed into a film, work synergistically to provide better protection of porous building materials from water penetration than when using the standard coalescent, ethylene glycol monobutyl ether. While not wishing to be bound by theory, it is believed that the alkoxysilane coalescing agent in the aqueous silane coalescing emulsion acts as a coalescing agent by: effectively lower the minimum film forming temperature and assist in film formation of the acrylic polymer in an aqueous acrylic polymer dispersion at room temperature using a mechanism similar to that of the standard coalescent agent, ethylene glycol monobutyl ether.

For the various embodiments, the aqueous coating composition of the present disclosure does not include another coalescent agent in addition to the alkoxysilane coalescent agent. In other words, the alkoxysilane coalescent provides the only coalescent to the aqueous dispersion of acrylic polymer in the aqueous coating composition of the present disclosure. Alternatively, for various embodiments, one or more additional coalescents as known in the art may be used with the alkoxysilane coalescent of the aqueous coating composition as provided herein for use in the aqueous acrylic polymer dispersion in the aqueous coating composition of the present disclosure. Coalescing agents are used to aid in the formation of a film in a film-forming composition, as is typical in the art. Coalescents aid in film formation, particularly by lowering the minimum film-forming temperature (MFFT) of one or more polymers dispersed in the composition. Reducing the MFFT of the one or more polymers contributes to their better coalescence, with the coalescing agent acting as a transient plasticizer for the one or more polymers. Thus, the coalescing agent facilitates film formation at a temperature below the MFFT of the polymer or polymers present in the composition. Examples of known coalescents include glycol ethers, such as propylene glycol alkyl ethers and dipropylene glycol alkyl ethers, including DOWANOL^TMPnP, DOWANOL PnB, and DOWANOL DPnB; ethylene glycol monobutyl ether, e.g. butyl CELLOSOLVE^TMSolvent and Texanol^TMAn ester alcohol.

Surprisingly, the use of alkoxysilane coalescing agents as provided in the present disclosure has not been recognized, nor has they been used as coalescing agents in coating compositions for controlling weathering in porous building materials. Furthermore, the use of aqueous silane coalescing emulsions in providing alkoxysilane coalescents as provided in the present disclosure demonstrates low volatility and does not include other Volatile Organic Compounds (VOCs), both of which are very environmentally beneficial. Thus, it is possible that the aqueous coating composition of the present disclosure does not include any other coalescent agent or agents, other than the alkoxysilane coalescent agent as provided in the present disclosure, as they are not needed.

Aqueous coating composition

For the various embodiments, the aqueous coating composition includes a binder having: an acrylic polymer in an aqueous acrylic polymer dispersion, wherein the acrylic polymer has a glass transition temperature (Tg) of 1 ℃ to 60 ℃; and an alkoxysilane coalescing agent in the aqueous silane coalescing emulsion. The aqueous coating composition may optionally further comprise an additive selected from the group consisting of: pigments, fillers, and combinations thereof. For the various embodiments, the aqueous coating composition of the present disclosure includes 3.5 to 100 weight percent (wt%) of a binder and 96.5 to 0 wt% of an additive selected from the group consisting of: pigments, fillers, and combinations thereof. The weight% of the binder and additives are based on the total dry weight of the aqueous coating composition.

For clarity, when ingredients of the aqueous coating composition are described as being present in weight percent, it is understood that the weight percent is based on the dry weight of the aqueous coating composition, and the dry weight of all ingredients, including any optional additives, will total 100 weight percent. For example, the weight% of the binder and additives are based on the total dry weight of the aqueous coating composition and will total 100 weight%, without regard to the water phase used in the aqueous coating composition. Thus, when the binder is 90 wt.%, for example, the additive is 10 wt.% of the aqueous coating composition, to achieve 100 wt.% (dry weight basis) of the aqueous coating composition.

Individual values and subranges from 3.5 to 100 weight percent binder and 96.5 to 0 weight percent additive are included and disclosed herein. For example, the aqueous coating composition may include a binder from a lower value of 3.5, 4, 5, 6, 7, 10, 15, 20, 25, or 30 wt% to an upper value of 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 99, or 100 wt%, while the additive may include an additive from a lower value of 0, 1, 5, 10, 15, 20, 25, 30, 35, 40, 45, or 50 wt% to an upper value of 70, 75, 80, 85, 90, 92, 94, or 96.5 wt%. Preferably, the range includes 3.5 to 85 wt% binder and 0.1 to 15 wt% additive. More preferably, the range includes 3.5 to 70 wt% binder and 0.15 to 15 wt% additive. Most preferably, the range includes 3.5 to 60 weight percent binder and 0.2 to 10 weight percent additive. In a particular embodiment, 100 weight percent of the binder forms the aqueous coating composition, with weight percent being based on the total dry weight of the aqueous coating composition.

Adhesive agent

The adhesive of the present disclosure comprises 85 to 97 weight percent acrylic polymer in an aqueous dispersion of acrylic polymer on a dry weight basis, based on the total dry weight of the adhesive, wherein the acrylic polymer has a glass transition temperature (Tg) of 1 ℃ to 60 ℃; and 15 to 3 weight percent of an alkoxysilane coalescing agent in the aqueous silane coalescing emulsion. When the ingredients of the binder of the aqueous coating composition are described as being present in weight percent, it is understood that the weight percent basis is the dry weight of the binder, and the dry weight of all ingredients will total 100 weight percent. The weight% of acrylic polymer and alkoxysilane coalescing agent in the binder is based on the total dry weight of the binder and will total 100 weight% without regard to the aqueous phase used in the acrylic polymer aqueous dispersion or aqueous silane coalescing emulsion. Thus, when the acrylic polymer in the aqueous acrylic polymer dispersion is 85 weight percent, for example, the alkoxysilane coalescing agent in the aqueous silane coalescing emulsion will be 15 weight percent to achieve 100 weight percent (on a dry basis) of binder.

All individual values and subranges from 85 to 97 weight percent acrylic polymer in the acrylic polymer aqueous dispersion and from 15 to 3 weight percent alkoxysilane coalescing agent in the aqueous silane coalescing emulsion are included and disclosed herein. For example, the binder may include acrylic polymer in an acrylic polymer aqueous dispersion having a lower value of 85, 86, 88, 90 wt% to an upper value of 92, 94, 95, or 97 wt%, while the alkoxysilane coalescing agent in the aqueous silane coalescing emulsion may include alkoxysilane coalescing agent in the aqueous silane coalescing emulsion having a lower value of 3, 5, 6, or 8 wt% to an upper value of 10, 12, 14, or 15 wt%. Preferably, the range includes 97 to 85 weight percent acrylic polymer and 3 to 15 weight percent alkoxysilane coalescing agent. More preferably, the range includes 96.5 to 88 weight percent acrylic polymer and 3.5 to 12 weight percent alkoxysilane coalescing agent. Most preferably, the range includes 95 to 90 weight percent acrylic polymer and 5 to 10 weight percent alkoxysilane coalescing agent.

Acrylic acid polymer

As used herein, an aqueous acrylic polymer dispersion refers to a mixture of acrylic polymers in a water-based continuous phase. As used herein, an aqueous acrylic polymer dispersion refers to a water-based emulsion in which the acrylic polymer of the aqueous acrylic polymer dispersion is formed from nonionic monomers selected from the group consisting of: methyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, styrene, butyl methacrylate, 2-ethylhexyl acrylate, tert-butyl acrylate, alpha-methylstyrene, vinyl acetate, hexyl acrylate, and combinations thereof. The use of the term "(meth)" followed by another term such as methacrylate refers to both acrylates and methacrylates. Preferably, the acrylic polymer of the aqueous acrylic polymer dispersion is formed from a nonionic monomer selected from the group consisting of: methyl methacrylate and butyl acrylate. Preferably, the acrylic polymer of the aqueous acrylic polymer dispersion is formed from a nonionic monomer selected from the group consisting of: methyl methacrylate and 2-ethylhexyl acrylate.

For the various examples, the acrylic polymer in the aqueous acrylic polymer dispersion has a glass transition temperature (Tg) of 1 ℃ to 60 ℃. Preferably, the Tg of the acrylic polymer in the aqueous acrylic polymer dispersion is from 5 ℃ to 55 ℃. More preferably, the Tg of the acrylic polymer in the aqueous acrylic polymer dispersion is from 10 ℃ to 50 ℃. The Tg value of an acrylic polymer can be calculated using Fox equation (t.g.fox, american society for physics, gazette (ball.am. physics Soc.), volume 1, phase 3, page 123 (1956)), wherein the Tg of a copolymer of monomers M1 and M2 is calculated using the following equation:

1/Tg (calculated) ═ w (M1)/Tg (M1) + w (M2)/Tg (M2)

Wherein Tg (calculated) is the glass transition temperature calculated for the copolymer; w (M1) is the weight fraction of monomer M1 in the copolymer; w (M2) is the weight fraction of monomer M2 in the copolymer; tg (M1) is the glass transition temperature of homopolymer of M1; tg (M2) is the glass transition temperature of the homopolymer of M2, all temperatures in kelvin. The glass transition temperature of homopolymers can be found, for example, in "Handbook of polymers" (edited by j. brandrup and e.h. immergut, international scientific press (Interscience Publishers). The contribution of copolymerized graft-linking monomers is excluded herein in calculating Tg. The calculated Tg is calculated from the total overall composition of the acrylic polymer particles.

The acrylic polymer is substantially uncrosslinked, i.e., the acrylic polymer comprises less than 1 weight percent, preferably less than 0.2 weight percent, and more preferably 0 percent, of copolymerized polyethylenically unsaturated monomer, based on the weight of the polymer. The polyethylenically unsaturated monomers include, for example, allyl (meth) acrylate, diallyl phthalate, 1, 4-butanediol di (meth) acrylate, 1, 2-ethylene glycol di (meth) acrylate, 1, 6-hexanediol di (meth) acrylate, and divinylbenzene.

The aqueous acrylic polymer dispersions used in the various embodiments may also have an acid content of acid monomers of up to 2 weight percent based on the dry weight of the acrylic polymer. Acid monomers include carboxylic acid monomers such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, fumaric acid, maleic acid, monomethyl itaconate, monomethyl fumarate, monobutyl fumarate, and maleic anhydride; and sulfur and phosphorus containing acid monomers. Preferred acid monomers are carboxylic acid monomers. A more preferred monomer is (meth) acrylic acid. The acid content can be calculated by determining the number of milliequivalents per gram of acid in the acrylic polymer and multiplying by the molecular weight of the potassium hydroxide.

Polymerization techniques for preparing acrylic polymers for the acrylic polymer aqueous dispersion include emulsion polymerization, which are well known in the art (e.g., examples disclosed in U.S. Pat. Nos. 4,325,856; 4,654,397; and 4,814,373, etc.). Conventional surfactants may be used, such as anionic and/or nonionic emulsifiers, for example alkali metal or ammonium alkyl sulfates, alkyl sulfonic acids, fatty acids and ethoxylated alkylphenols. The amount of surfactant used may be from 0.1 to 6 weight percent based on the weight of the total monomers. Either a thermal or redox initiation process may be used. Conventional free radical initiators such as hydrogen peroxide, t-butyl hydroperoxide, t-amyl hydroperoxide, ammonium and/or alkali metal persulfates may be used, typically at levels of 0.01 to 3.0 weight percent based on the weight of the total monomers. Redox systems using the same initiators coupled with suitable reducing agents (e.g., sodium formaldehyde sulfoxylate, sodium bisulfite, erythorbic acid, hydroxylamine sulfate, and sodium bisulfite) can be used at similar levels, optionally in combination with metal ions such as iron and copper, optionally additionally including metal complexing agents. The monomer mixture for a certain stage can be added neat or in the form of an emulsion in water. The monomer mixture for a stage can be added in a single addition or in multiple additions using homogeneous or different compositions or continuously over the reaction period allotted to the stage; preferred are emulsions in which one or more of the polymeric monomers are added in a single addition. Additional ingredients such as free radical initiators, oxidizing agents, reducing agents, chain transfer agents, neutralizing agents, surfactants, and dispersants may be added before, during, or after any stage.

The acrylic polymer particles may have an average particle diameter of 40 to 1000 nanometers (measured using a Brookhaven Instruments particle size analyzer). The acrylic polymer aqueous dispersion of the present disclosure may have a solid content of 30 to 70% by weight, based on the total weight of the acrylic polymer aqueous dispersion. The viscosity of the aqueous acrylic polymer dispersions of the present disclosure can be from 10 centipoise to 9000 centipoise as measured using a Brookfield viscometer (Brookfield viscometer); the viscosity changes significantly for different coating methods. The acrylic polymer aqueous dispersion of the present disclosure may have a pH of 3 to 11 as measured at 23 ℃.

Representative, non-limiting examples of commercially produced acrylic polymer aqueous dispersions suitable for use in the adhesives of the present disclosure include those sold under the trade names: PRIML^TMSS-640、PRIMAL^TMAC-339、PRIMAL^TME-822K、UCAR^TMLatex DL 420G、PRIMAL^TMAC-337ER、PRIMAL^TMCM-330、PRIMAL^TMAC-285 and PRIML^TMCM-160 (all available from Dow, Inc.).

Alkoxysilane coalescents

By aqueous silane coalescing emulsion is meant a mixture of two immiscible liquids in which an alkoxysilane coalescing agent is dispersed in an aqueous based continuous phase. For the various embodiments, the alkoxysilane coalescing agent is selected from the group consisting of: r¹Si(OR)₃、(R¹)₂Si(OR)₂And combinations thereof, wherein each R¹Independently selected from an alkyl group having 1 to 20 carbon atoms, a substituted alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or a substituted aryl group having 6 to 20 carbon atoms, and wherein each R is independently selected from an alkyl group having 1 to 6 carbon atoms. More specifically, for the various examples, the alkoxysilane coalescing agent is R¹Si(OR)₃. When the alkoxysilane coalescing agent is R¹Si(OR)₃For various embodiments, R¹Has 8 carbon atoms and R has 2 carbon atoms to provide triethoxy (octyl) silane. Or, R¹Has 6 carbon atoms and R has 2 carbon atoms to provide triethoxy (hexyl) silane.

Unless otherwise indicated, the term "substituted" as used with respect to another group (e.g., alkyl) means that one or more hydrogen atoms in the alkyl group have been replaced with another substituent. Examples of such substituents include alkyl groups having 1 to 6 carbon atoms, halogen atoms such as chlorine, fluorine, bromine and iodine; halogen atom-containing groups such as chloromethyl group, perfluorobutyl group, trifluoroethyl group, and nonafluorohexyl group; an oxygen atom; oxygen atom-containing groups such as (meth) acrylic acid and carboxyl groups; a nitrogen atom; nitrogen atom-containing groups such as amine, amino-functional group, amido-functional group, and cyano-functional group; a sulfur atom; and groups containing sulfur atoms, such as mercapto groups.

Forming the aqueous silane coalescing emulsions of the present disclosure may include forming a mixture by combining a desired ratio of alkoxysilane coalescing agent with water or a water-based solution, and mixing and homogenizing to form the aqueous silane coalescing emulsions of the present disclosure. As used herein, water may include deionized water, while a water-based solution may include water and one or more hydrophilic additives. Such hydrophilic additives include, but are not limited to, low molecular weight alcohols such as methanol, ethanol, propanol, isopropanol, and the like. One or more of a foam control agent and/or a pH control agent may be included with the aqueous silane coalescing emulsion as desired.

Mixing to form the aqueous silane coalescing emulsion can be achieved by known methods and can occur in a batch, semi-continuous, or continuous process. Forming the aqueous silane coalescing emulsions of the present disclosure may include adding 30 to 900 parts of water or water-based solution per 100 parts of alkoxysilane coalescing agent. This allows the aqueous silane coalescing emulsion to have a "solids" content of 5% to 80% by volume. The alkoxysilane coalescing agent may have an average volume particle size of 0.1 to 5 μm. Viscosity of the aqueous silane coalescing emulsions of the present disclosure as measured using a brookfield viscometer; the viscosity suitable for different coating methods varies considerably, depending on the actual solids content.

The process of combining and mixing the components of the aqueous silane coalescing emulsion may occur in a single-step or multi-step process. Thus, the components may all be combined and subsequently mixed by any of the techniques described herein. Alternatively, one or more portions of the components may be combined first, mixed, and then additional quantities of the components combined and mixed in addition. Those skilled in the art will be able to select the optimum portion of the components for carding and mixing, depending on the selection of the amounts used in forming the aqueous silane coalescing emulsion and the particular mixing technique utilized.

Representative, non-limiting examples of commercially produced aqueous silane coalescing emulsions suitable for use in the adhesives of the present disclosure include those under the trade name DOWSIL^TMIE-6692 (dow corporation).

The aqueous coating composition can be prepared by techniques well known in the coating art. Acrylic polymer aqueous dispersion and aqueous silane coalescent emulsionThe liquid may be added with optional additives and coating aids, as desired, under low shear agitation. In addition to the aqueous acrylic polymer dispersion and the aqueous silane coalescing emulsion, the aqueous coating composition may also contain optional additives. Examples of such additives include, but are not limited to, inorganic fillers such as calcium carbonate (CaCO)₃) Quartz, biocide (when water is present), untreated and treated silica; metal hydroxide fine powders such as aluminum hydroxide fine powder, calcium hydroxide fine powder and magnesium hydroxide fine powder; a bisamide; plate-like fillers, such as mica, dimethylpolysiloxane, epoxy-functional diorganopolysiloxane and amino-functional diorganopolysiloxane. The additive may further comprise a pigment, as known in the art. Other additives also include curing agents, buffers, corrosion inhibitors, neutralizing agents, humectants, wetting agents, defoamers, UV absorbers, fluorescent brighteners, light or heat stabilizers, biocides, dispersants, colorants, colorant dispersions, waxes, water repellents, pigments, extenders, antioxidants, and dyes may be added to the coating composition. Additional components that may also be included in the coating composition may be preservatives, freeze/thaw additives, and various thickeners.

The aqueous coating compositions of the present disclosure can be used to help control weathering in porous building materials. For the various embodiments, an aqueous coating composition as provided herein can have an amount of water sufficient to provide the aqueous coating composition with a solids content of 2 to 70 weight percent, based on the total weight of the aqueous coating composition. Mixing to form an aqueous coating composition having a solids content of from 2 to 70% by weight, based on the total weight of the aqueous coating composition, can be achieved by known methods and can be carried out as a batch, semi-continuous or continuous process. The aqueous coating composition forming the disclosed aqueous coating composition can include water or an aqueous coating composition as provided herein to achieve a solids content of 2 to 70 weight percent based on the total weight of the aqueous coating composition. As will be appreciated, the solids content to obtain the aqueous coating composition will depend on the solids content of each of the aqueous acrylic polymer dispersion and the aqueous silane coalescing emulsion.

The process of combining and mixing the aqueous acrylic polymer dispersion and the aqueous silane coalescing emulsion can be performed in a single or multi-step process. Thus, the components may all be combined and subsequently mixed by any of the techniques described herein. Alternatively, one or more portions of the components may be combined first, mixed, and then additional quantities of the components combined and mixed in addition. Those skilled in the art will be able to select the optimum portion of the components for combing and mixing, depending on the selection of the amounts used to form the aqueous coating composition and the particular mixing technique utilized.

As discussed herein, embodiments of the aqueous coating compositions can be used to control efflorescence in porous building materials. The aqueous coating compositions of the present disclosure can be used to form a film on porous building materials. In particular, the present disclosure includes porous building materials at least partially coated with a membrane formed with an aqueous coating composition as provided herein. For example, the aqueous coating compositions of the present disclosure can be used to at least partially coat and subsequently form a membrane porous building material. Examples of the porous building material may include an inorganic porous building material, wherein the inorganic porous building material may be a cement-based porous building material. Other examples of inorganic porous building materials include, but are not limited to, bricks, clays, fiber cement, concrete, gypsum, stucco, drywall, and mortar, which are new and have not previously been painted or treated, surfaces that have not previously been printed, painted, or primed, or surfaces that have not been weathered. Other examples of porous building materials may include organic porous building materials, wherein the organic porous building materials may be cellulose-based building materials. Other examples of organic porous building materials include, but are not limited to, wood, Oriented Strand Board (OSB), particle board, chip board, and Medium Density Fiberboard (MDF).

In providing a film formed with the aqueous coating composition of the present disclosure, the aqueous coating composition of the present disclosure is applied to a porous building material and dried or allowed to dry. Aqueous coating compositions are typically applied to porous building materials using conventional coating application methods such as paintbrushes, paint rollers, gravure printing rollers, curtain coaters, and spraying methods such as air atomized sprays, air assisted sprays, airless sprays, high volume low pressure sprays, and air assisted airless sprays. Drying of the aqueous coating composition may be carried out at ambient conditions, for example at 5 ℃ to 35 ℃, or the coating may be dried at elevated temperatures, for example at 35 ℃ to 100 ℃.

The following examples are provided to illustrate the present disclosure.

Examples of the invention

In examples, various terms and names of materials are used, including, for example, the following:

TABLE 1 bill of materials

Minimum Film Forming Temperature (MFFT)

The Minimum Film Forming Temperature (MFFT) of the aqueous coating composition is the lowest temperature at which the aqueous coating composition forms an actual film. MFFT is measured using ASTM standard D2354-10. For this test method, the MFFT was determined as the lowest temperature within a controlled temperature gradient, where the film became optically clear and mechanical integrity was achieved. In addition to the visual MFFT, the mechanical MFFT was also determined by locating the lowest temperature at which the aqueous coating composition formed a film with some mechanical strength.

To determine the coalescent efficiency, that is, the ability to reduce the MFFT of different molecules, the MFFT was measured at various coalescent levels. Tables 2A and 2B show various acrylic polymer aqueous dispersion binders with alkoxysilane coalescents (Dowsil) at various levels^TMIE-6692) or butyl CELLOSOLVE^TMMFFT of solvent. The weight percentages of the coalescent content are based on the dry weight of the acrylic polymer in the aqueous acrylic polymer dispersion.

For molecules to behave as effective coalescents, the glass transition temperature (Tg) of the acrylic polymer in the aqueous dispersion binder with which it is blended must be lowered. The coalescent agent must also be compatible with the acrylic polymer aqueous dispersion of interest and have a lower Tg than the acrylic polymer aqueous dispersion binder itself. For a given type of molecule, the compatibility (or solubility) will generally decrease as the molecular weight increases due to entropy effects.

Tables 2A and 2B provide visual MFFT data for the following: examples (EX)1 to 14 with coalescent Dowsil at 6 or 12 wt% effective coalescent/dry binder content^TMIE-6692; and comparative examples (CEx) a to Q without coalescent or using butyl CELLOSOLVE at 6 or 12 wt% content coalescent/dry binder content^TM. Tables 2A and 2B show that for each formulation, following Dowsil^TMThe IE-6692 content concentration increases and the MFFT decreases. At both 6 and 12 wt% levels, the MFFT of the aqueous coating composition of the present disclosure exhibited a reduction in MFFT value compared to the absence of any coalescent, but was closer to using the reference coalescent, butyl CELLOSOLVE^TMThe value of the solvent.

TABLE 2A-Minimum Film Forming Temperature (MFFT) of the aqueous coating composition

TABLE 2B-MFFT of waterborne coating compositions

Kinetics of film formation

Use ofRheolaser coating apparatus (formulation) measuring film forming speckle fluence rate dynamics of an aqueous coating composition, wherein the method is based on multiple speckle dispersive wave spectroscopy. Briefly, in this test, monitoring the film-forming speckle rate dynamics was performed by measuring the rate of speckle image fluctuation during the drying process of the film applied to an uncoated glass substrateAnd it is related to the speed of movement of the scatter in the sample. The laser irradiates the surface of the dried film and the light is scattered due to the change in microstructure. The detector captures the backscattered light and forms a speckle image, which by comparing different speckle images with the changing intensity, creates a pattern and can help identify the drying mechanism and characteristic drying times. Rapid structural changes during the drying process of the film produce high speckle rates due to events such as solvent evaporation and particle diffusion. As the motion of scattering slows due to the filling and interdiffusion of the particles forming the phase film, the speckle rate decreases and becomes constant over time.

The aqueous coating composition is prepared using a ratio of acrylic polymer to coalescent agent (weight: weight based on total weight of aqueous coating composition) of 90:10 to 95: 5. Using 95:05 of monobutyl acrylate CELLOSOLVE^TMThe solvent ratio was taken as reference coalescent. A 60 μm thick wet draw down of the selected formulation was applied using a gap coating applicator on an uncoated glass substrate using an automatic controlled coater (K controlled coater, RK Printcoat instrument) operating at a speed of 4 m/min (min). Immediately thereafter, use is made as described aboveThe film formation kinetics were measured with a rheoloser coating apparatus (formation).

Referring now to FIGS. 1A-1H, it can be seen that for the same acrylic adhesive composition, the adhesive composition has a butyl group CELLOSOLVE^TMAqueous coating compositions with solvent, Dowsil^TMIE-6692 forms a waterborne coating composition that exhibits similar speckle rate dynamics despite slower drying progress. Dowsil^TMIE-6692 is similar to the reference coalescing agent (butyl CELLOSOLVE) in the film forming process of acrylic latex^TMSolvent) mechanism. For using Dowsil^TMOne advantage of slower drying progression for the example waterborne coating composition formed from IE-6692 is that the additional time to film formation can allow more silane groups to migrate to the surface of the film.

Water absorption test

The waterproofing performance of films formed on fiber cement boards using different aqueous coating compositions was evaluated using a RILEM (Renion International des laboratories d' Essais et de Recochessur les materials et al constraints) test 11.4 (Water offset plate), which was designed to measure the masonry material surface (5 cm)²An outer exposed surface) the amount of water absorbed over a specified period of time. In this test, the rate of water movement through the fiber cement material is measured and can be used to assess the degree of protection provided by the water repellency treatment. After various times, in milliliters or cubic centimeters (cm)³) The water absorption per fiber cement board sample in units is seen in fig. 2A and 2B. Untreated fiber cement boards were used as reference. The values in FIGS. 2A and 2B are in cm³Is the unit of absorbed water.

The aqueous coating composition is prepared using a ratio of acrylic polymer to coalescent agent (weight: weight based on total weight of aqueous coating composition) of 90:10 to 95: 5. Using 95:05 of monobutyl acrylate CELLOSOLVE^TMThe solvent ratio was taken as reference coalescent. 200g/m²The aqueous coating composition of (a) is applied as a substrate on the surface of an uncoated fiber cement panel and kept dry at room temperature (23 ℃). Thereafter, a RILEM tube was mounted on top of the dried coated substrate and deionized water was added through the upper open end of the tube until a zero (0) scale mark. The sample was kept at room temperature (23 ℃) and the amount of water absorbed by the fiber cement board sample was recorded at specific intervals. Uncoated fiber cement boards were used as reference.

Fig. 2A and 2B show that excellent water repellency is obtained even over extended (long term) periods of time using alkoxysilane coalescing agents according to the present disclosure. It can be clearly seen that the same acrylic binder as butyl CELLOSOLVE used after each time interval test was used^TMSample comparison of solvents, using Dowsil^TMIE-6692 all the panels treated with the formulation blend had a lower volume of water uptake. These results show that Dowsil in aqueous coating compositions compares to the use of standard coalescents^TMThe presence of IE-6692 contributes to better performance of the fiber cement surface against water.