Polymer latex for construction applications

Abstract

The present invention relates to a polymer latex obtained by aqueous emulsion polymerization of a mixture of ethylenically unsaturated monomers comprising a) a vinyl aromatic compound; b) a conjugated diene; c) a hydroxyalkyl ester of an ethylenically unsaturated acid in an amount of 2 to 10 wt.-%, based on the total weight of monomers; and d) an ethylenically unsaturated carboxylic acid or a salt thereof in an amount of 0 to 0.15 wt.-%, based on the total weight of monomers; wherein the weight ratio of the vinyl aromatic compound to the conjugated diene is at least 1.3:1, and the polymer latex comprises 2 to 10 wt.-% of a non-ionic surfactant having an HLB of 17 to 19, based on the total weight of monomers. The present invention further relates to a building material, preferably a cement composition, comprising the polymer latex.

Description

[0001] This invention relates to polymer latexes for construction applications, and specifically, but not exclusively, to cement compositions. The invention also relates to building materials comprising such polymer latexes, particularly cement compositions. Background of the Invention

[0003] US4,368,077 relates to styrene-butadiene-based latex and its use in cement compositions. The SBR latex is prepared by emulsion polymerization in the presence of N-hydroxymethylmethacrylamide and anionic surfactant, wherein the weight ratio of styrene to butadiene is greater than 1.5.

[0004] WO2003 / 27039 relates to SBR latex for use in gypsum-bonded wall panels. The disclosed SBR latex is preferably functionalized with 2-acrylamido-2-methylpropanesulfonic acid or its salt. In a preferred embodiment, the latex is polymerized from a monomer composition comprising 2-6 wt% 2-acrylamido-2-methylpropanesulfonic acid, 65-80 wt% styrene, 15-13 wt% butadiene, 0-3 wt% hydroxyethyl acrylate, and 0-10 wt% acrylonitrile. This application discloses polymerization in the presence of anionic surfactants. Nonionic surfactants may also be present. However, no disclosure is made regarding the amount of nonionic surfactant.

[0005] EP1024154 discloses a styrene-butadiene rubber for use in cement compositions. The styrene to butadiene weight ratio is greater than 1.5, and acrylamide methylpropane sulfonic acid is present in the seed for latex polymerization. In the examples, anionic surfactants are used, and hydroxyethyl acrylate may be present in an amount of 1.5% by weight.

[0006] WO2014 / 122031 relates to SBR latex for use in cement compositions and aims to reduce costs by replacing butadiene with esters of unsaturated carboxylic acids. This reference discloses core-shell latex particles, wherein the core comprises a vinyl aromatic compound and an ester of an unsaturated carboxylic acid. In addition to hydroxyalkyl acrylates, olefinic unsaturated acids and other functional monomers may be present. The shell comprises a vinyl aromatic monomer and a conjugated diene, and up to 10% by weight of additional monomers, such as hydroxyalkyl acrylates. No general description is given regarding surfactants and their amounts. In the examples, monomer compositions without hydroxyalkyl acrylates are used, and the amount of nonionic surfactant is 0.33% by weight, based on the total weight of the monomers.

[0007] None of the cited literature addresses the improved properties of cement compositions imparted by the addition of polymer latex, such as spreadability, retarding, and strength development. Therefore, according to one aspect of the invention, an object of the invention is to provide a polymer latex that imparts an improved balance of properties, such as spreadability, retarding, and strength development, to cement compositions containing said polymer latex. Invention Overview

[0009] According to one aspect of the invention, this object has been surprisingly achieved by a polymer latex obtained by aqueous emulsion polymerization of a mixture of olefinically unsaturated monomers, the mixture of olefinically unsaturated monomers comprising:

[0010] a) Vinyl aromatic compounds;

[0011] b) Conjugated dienes;

[0012] c) Hydroxyalkyl esters of olefinic unsaturated acids, in an amount of 2-10% by weight based on the total weight of the monomers; and

[0013] d) An olefinic unsaturated carboxylic acid or its salt, in an amount of 0-0.15% by weight based on the total weight of the monomers;

[0014] The vinyl aromatic compound to conjugated diene has a weight ratio of at least 1.3:1, and the polymer latex contains 2-10% by weight of a nonionic surfactant having an HLB of 17-19, based on the total weight of the monomers.

[0015] In other respects, the present invention relates to the use of the polymer latex in cement compositions and cement compositions containing the polymer latex.

[0016] Detailed description of the invention

[0017] Monomer mixtures:

[0018] The polymer latex of the present invention is obtained by aqueous emulsion polymerization of a mixture of olefinically unsaturated monomers, wherein the mixture of olefinically unsaturated monomers comprises:

[0019] a) Vinyl aromatic compounds;

[0020] b) Conjugated dienes;

[0021] c) Hydroxyalkyl esters of olefinic unsaturated acids, in an amount of 2-10% by weight based on the total weight of the monomers; and

[0022] d) An olefinic unsaturated carboxylic acid, in an amount of 0-0.15% by weight based on the total weight of the monomers;

[0023] The weight ratio of the vinyl aromatic compound to the conjugated diene is at least 1.3:1.

[0024] Representative vinyl aromatic monomers include, for example, styrene, α-methylstyrene, vinyltoluene, o-methylstyrene, p-methylstyrene, p-tert-butylstyrene, 2,4-dimethylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2-ethylstyrene, 3-ethylstyrene, 4-ethylstyrene, 2,4-diisopropylstyrene, 2,4-dimethylstyrene, 4-tert-butylstyrene, 5-tert-butyl-2-methylstyrene, 2-chlorostyrene, 3-chlorostyrene, 4-chlorostyrene, 4-bromostyrene, 2-methyl-4,6-dichlorostyrene, 2,4-dibromostyrene, vinylnaphthalene, vinyltoluene and vinylxylene, 2-vinylpyridine, 4-vinylpyridine, and 1,1-diphenylethylene and substituted 1,1-diphenylethylene, 1,2-diphenylethylene and substituted 1,2-diphenylethylene. Mixtures of one or more of the aforementioned vinyl aromatic compounds may also be used. Preferred monomers are styrene and α-methylstyrene, with styrene being the most preferred. The amount of the vinyl aromatic compound may be in the range of 24-70% by weight, preferably in the range of 38-65% by weight, more preferably in the range of 40-60% by weight, based on the total weight of the olefinically unsaturated monomers. Therefore, the amount of the vinyl aromatic compound present may not exceed 70% by weight, 68% by weight, 65% by weight, 63% by weight, 60% by weight, or 58% by weight, based on the total weight of the olefinically unsaturated monomers. The vinyl aromatic compound may be present in amounts of at least 24% by weight, at least 30% by weight, at least 33% by weight, at least 35% by weight, at least 38% by weight, or at least 40% by weight, based on the total weight of the olefinically unsaturated monomers. Those skilled in the art will understand that any range defined by any of the lower and upper limits of the above disclosure is disclosed herein.

[0025] The conjugated diene monomers suitable for use in this invention include those selected from the group consisting of: 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2-chloro-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, 2,4-hexadiene, 1,3-octadiene, 2-methyl-1,3-pentadiene, 2,3-dimethyl-1,3-pentadiene, 3,4-dimethyl-1,3-hexadiene, 2,3-diethyl-1,3-butadiene, 4,5-diethyl-1,3-octadiene, 3-butyl-1,3-octadiene, 3,7-dimethyl-1,3,6-octtriene, 2-methyl- 6-Methylene-1,7-octadiene, 7-methyl-3-methylene-1,6-octadiene, 1,3,7-octtriene, 2-ethyl-1,3-butadiene, 2-pentyl-1,3-butadiene, 3,7-dimethyl-1,3,7-octtriene, 3,7-dimethyl-1,3,6-octtriene, 3,7,11-trimethyl-1,3,6,10-dodecanetraene, 7,11-dimethyl-3-methylene-1,6,10-dodecanetraene, 2,6-dimethyl-2,4,6-octtriene, 2-phenyl-1,3-butadiene, and 2-methyl-3-isopropyl-1,3-butadiene, 1,3-cyclohexadiene, myrcene, ocimene, and farnesene. 1,3-Butadiene, isoprene, and combinations thereof are preferred conjugated dienes. 1,3-Butadiene is the most preferred diene. Typically, the amount of the conjugated diene monomer can range from 15 to 45 wt%, preferably from 20 to 40 wt%, and more preferably from 24 to 39 wt%, based on the total weight of the monomers. Therefore, the conjugated diene can be present in an amount of at least 15 wt%, at least 20 wt%, at least 22 wt%, or at least 24 wt%, based on the total weight of the olefinically unsaturated monomers.

[0026] Therefore, the amount of the conjugated diene monomer may not exceed 45% by weight, 43% by weight, 40% by weight, 39% by weight, or 38% by weight, based on the total weight of the olefinically unsaturated monomer. Those skilled in the art will understand that any range between any of the explicitly disclosed lower and upper limits is disclosed herein.

[0027] The weight ratio of the vinyl aromatic compound to the conjugated diene in the monomer mixture is at least 1.3:1, preferably at least 1.5:1, more preferably at least 1.6:1, even more preferably at least 1.8:1, even more preferably at least 1.9:1, and most preferably at least 2.0:1.

[0028] The hydroxyalkyl esters of olefinically unsaturated acids that can be used to prepare the polymer latex of the present invention include hydroxyalkyl acrylate and hydroxyalkyl methacrylate monomers based on ethylene oxide, propylene oxide, and higher epoxides or mixtures thereof. Examples are hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, and hydroxybutyl acrylate. Preferably, the (meth)acrylate hydroxyalkyl ester monomer is 2-hydroxyethyl (meth)acrylate or 2-hydroxypropyl (meth)acrylate. The (meth)acrylate hydroxyalkyl ester monomer is present in an amount of 2 to 10% by weight, preferably 2 to 9% by weight, more preferably 2 to 7% by weight, and most preferably 2 to 6% by weight, based on the total weight of the olefinically unsaturated monomers.

[0029] The monomer mixture of the present invention contains up to 0.15% by weight, preferably up to 0.1% by weight, more preferably up to 0.05% by weight, and even more preferably up to 0.01% by weight of an olefinically unsaturated carboxylic acid or its salt. Most preferably, the monomer mixture does not contain olefinically unsaturated carboxylic acids or their salts.

[0030] If present, the olefinically unsaturated carboxylic acid or its salts may be selected from monocarboxylic and dicarboxylic acid monomers and their anhydrides, and polycarboxylic acid esters. Examples of monocarboxylic acid monomers include acrylic acid, methacrylic acid, and crotonic acid. Examples of dicarboxylic acid monomers include fumaric acid, itaconic acid, maleic acid, cis-cyclohexene-1,2-dicarboxylic acid, dimethylmaleic acid, bromomaleic acid, 2,3-dichloromaleic acid, and (2-dodecen-1-yl)succinic acid. Examples of polycarboxylic acid esters include monomethyl maleate, monomethyl fumarate, monoethyl maleate, monoethyl fumarate, monopropyl maleate, monopropyl fumarate, monobutyl maleate, monobutyl fumarate, mono(2-ethylhexyl) maleate, and mono(2-ethylhexyl) fumarate. Other examples of olefinically unsaturated carboxylic acids include vinylacetic acid, vinyllactic acid, and their salts.

[0031] The monomer mixture of the present invention may optionally further comprise e) an olefinic unsaturated monomer that is copolymerizable with monomers a)-d) and is different from monomers a)-d).

[0032] The olefinic unsaturated monomer e) can be selected from:

[0033] e1) An olefinic unsaturated sulfonic acid, preferably present in the monomer mixture in an amount of 0-10% by weight, more preferably 0-6% by weight, even more preferably 0-4% by weight, even more preferably 0-2% by weight, even more preferably 0-1% by weight, based on the total weight of the olefinic unsaturated monomers.

[0034] e2) C1-C20 alkyl esters of acrylic acid or methacrylic acid, preferably in an amount of 0-25% by weight, more preferably 0-10% by weight, based on the total weight of the olefinically unsaturated monomers; and

[0035] e3) An olefinic unsaturated nitrile compound, preferably in an amount of 0-15% by weight, more preferably 0-10% by weight, based on the total weight of the olefinic unsaturated monomer.

[0036] The olefinically unsaturated sulfonic acid (e1) is preferably selected from styrene sulfonic acid, vinyl sulfonic acid, allyl sulfonic acid, methyl allyl sulfonic acid, 3-sulfopropyl (meth)acrylate, and 2-acrylamido-2-methylpropanesulfonic acid. Most preferably, the monomer mixture of the present invention does not contain olefinically unsaturated sulfonic acids.

[0037] Alkyl esters of olefinic unsaturated acids that can be used according to the present invention include n-alkyl esters, isoalkyl esters or tertiary alkyl esters of acrylic acid or (meth)acrylic acid, wherein the alkyl group has 1 to 20 carbon atoms.

[0038] Typically, preferred alkyl (meth)acrylates can be selected from (meth)acrylates C1-C. 10 Alkyl esters, preferably C1-C8 alkyl esters of (meth)acrylate. Examples of such acrylate monomers include n-butyl acrylate, sec-butyl acrylate, ethyl acrylate, hexyl acrylate, tert-butyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, 4-methyl-2-pentyl acrylate, 2-methylbutyl acrylate, methyl methacrylate, butyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, ethyl methacrylate, isopropyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, and hexadecyl methacrylate. Methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, and combinations thereof are preferred.

[0039] Typically, the amount of the (meth)acrylate alkyl ester monomer present may not exceed 25 wt%, 23 wt%, 20 wt%, 18 wt%, 16 wt%, 14 wt%, 12 wt%, 10 wt%, 8 wt%, 6 wt%, 4 wt%, 2 wt%, or 1 wt%, based on the total weight of the olefinic unsaturated monomer.

[0040] The unsaturated nitrile monomers (e3) that can be used according to the invention comprise polymerizable unsaturated aliphatic nitrile monomers containing 2 to 4 carbon atoms arranged in a straight or branched chain, and which may be substituted with acetyl or other nitrile groups. Such nitrile monomers include acrylonitrile, methacrylonitrile, α-cyanoethyl acrylonitrile, fumaric acid, and combinations thereof, with acrylonitrile being most preferred. The content of these nitrile monomers may not exceed 15% by weight, 14% by weight, 12% by weight, 10% by weight, 8% by weight, 6% by weight, 4% by weight, 2% by weight, or 1% by weight, based on the total weight of the olefinically unsaturated monomers.

[0041] According to the present invention, preferably the polymer latex does not contain core / shell particles.

[0042] The method for preparing polymer latex of the present invention:

[0043] The latex polymer (I) of the present invention can be prepared by any emulsion polymerization method known to those skilled in the art, provided that a monomer mixture as defined herein is used. The method described in EP-A 792 891 is particularly suitable.

[0044] In the emulsion polymerization used to prepare the polymer latex of the present invention, a seed latex can be used. The seed latex is preferably prepared separately, and the emulsion polymerization is carried out in the presence of the separately prepared seed latex. The seed latex particles are preferably present in an amount of 0.01-10 parts by weight, preferably 1-5 parts by weight, based on 100 parts by weight of the total olefinically unsaturated monomers used in the polymer latex, including those used to manufacture the seed particles, such as ethylene oxide-functionalized latex particles (b). Therefore, the lower limit of the amount of seed latex particles can be 0.01, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, or 2.5 parts by weight. The upper limit of the quantity may be 10, 9, 8, 7, 6, 5.5, 5, 4.5, 4, 3.8, 3.6, 3.4, 3.3, 3.2, 3.1, or 3 parts by weight. Those skilled in the art will understand that any range formed by any explicitly disclosed lower and upper limits is explicitly included in this specification.

[0045] The method for preparing the above-mentioned latex polymer (I) can be carried out at a temperature in the range of 0-130°C, preferably 0-100°C, particularly preferably 10-95°C, and very particularly preferably 20-90°C, in the absence of one or more emulsifiers, in the absence of one or more colloids, and in the presence of one or more initiators. The temperature includes all values ​​and sub-values ​​therebetween, particularly including 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, and 125°C.

[0046] Initiators that can be used in carrying out this invention include water-soluble and / or oil-soluble initiators effective for polymerization purposes. Representative initiators are well known in the art and include, for example, azo compounds (e.g., AIBN, AMBN, and cyanopentanoic acid) and inorganic peroxides, such as hydrogen peroxide, sodium, potassium, and ammonium persulfate, percarbonates, and perborates, as well as organic peroxides, such as alkyl hydroperoxides, dialkyl peroxides, acyl hydroperoxides, and diacyl peroxides, and esters, such as tert-butyl perbenzoate, and combinations of inorganic and organic initiators.

[0047] The amount of initiator is sufficient to initiate the polymerization reaction at the desired rate. Generally, an initiator dosage of 0.01-5% by weight, preferably 0.1-4% by weight, is sufficient based on the total polymer weight. The most preferred amount of initiator based on the total polymer weight is 0.01-2% by weight. The amount of initiator includes all values ​​and sub-values ​​within this range, particularly 0.01, 0.1, 0.5, 1, 1.5, 2, 2.5, 3, 4, and 4.5% by weight, based on the total polymer weight.

[0048] The aforementioned inorganic and organic peroxides can be used alone or in combination with one or more suitable reducing agents, as is known in the art. Examples of such reducing agents include sulfur dioxide, alkali metal sulfites, alkali metal and ammonium bisulfites, thiosulfates, dithionites, and formaldehyde hyposulfites, as well as hydroxylamine hydrochloride, hydrazine sulfate, ferric(II) sulfate, cuprous naphthate, glucose, sulfonic acid compounds such as sodium methanesulfonate, amine compounds such as dimethylaniline, and ascorbic acid. More preferably, proprietary organic sulfinic acid derivative sodium salts are used, for example... FF6 or FF6M. The amount of reducing agent is preferably 0.03-10 parts by weight per part by weight of polymerization initiator.

[0049] Surfactants or emulsifiers suitable for stabilizing latex particles include those conventional surfactants used in polymerization processes. One or more surfactants can be added to the aqueous phase and / or monomer phase. In seed processes, the effective amount of surfactant is selected to support the stabilization of particles as colloids, minimize inter-particle contact, and prevent aggregation. In non-seed processes, the effective amount of surfactant is selected to influence particle size.

[0050] Since the polymer latex of the present invention contains 2-10% by weight of a nonionic surfactant having an HLB of 17-19 based on the total weight of the olefinically unsaturated monomers, such an amount of nonionic surfactant can be used in the emulsion polymerization process. Alternatively, a portion of the total required amount of nonionic surfactant may be used in the emulsion polymerization process, and the remaining amount may be added to the final polymer latex after the emulsion polymerization process is terminated. Post-reaction addition of the nonionic surfactant is preferred.

[0051] Suitable nonionic surfactants having an HLB of 17-19 can be selected from alkyl ethoxylates, alkylphenol ethoxylates, fatty acid ethoxylates, ethylene glycol-propylene glycol block copolymers, or tristryryl phenol ethoxylates. Preferred nonionic surfactants have an HLB value of 17 to 18.5, more preferably 17 to 18. The HLB value is calculated as the quotient of the molar mass of the hydrophilic portion of the surfactant to the total molar mass of the surfactant multiplied by 20. The nonionic surfactant is present in the polymer latex of the present invention in an amount of 2-10% by weight, preferably 2-8% by weight, more preferably 2-7% by weight, based on the total weight of the olefinically unsaturated monomers.

[0052] Therefore, the amount of nonionic surfactant in the polymer latex of the present invention is at least 2% by weight, or may be at least 2.5% by weight, at least 3% by weight, at least 3.5% by weight, at least 4% by weight, at least 4.5% by weight, or at least 5% by weight, based on the total weight of the olefinically unsaturated monomers. The amount of nonionic surfactant in the polymer latex of the present invention is at most 10% by weight, or may be at most 9.5% by weight, at most 9% by weight, at most 8.5% by weight, at most 8% by weight, at most 7.5% by weight, at most 7% by weight, at most 6.5% by weight, at most 6% by weight, based on the total weight of the olefinically unsaturated monomers. Those skilled in the art will understand that all ranges formed by any of the limits defined above are disclosed herein.

[0053] Optionally, in addition to the aforementioned nonionic surfactants, anionic surfactants may also be used. Representative anionic surfactants include saturated and olefinically unsaturated sulfonic acids or their salts, including, for example, unsaturated hydrocarbon sulfonic acids such as vinyl sulfonic acid, allyl sulfonic acid, and methyl allyl sulfonic acid and their salts; aromatic acids such as p-styrene sulfonic acid, isopropenylbenzene sulfonic acid, and vinyloxybenzene sulfonic acid and their salts; sulfonyl alkyl esters of acrylic acid and methacrylic acid, such as sulfoethyl methacrylate and sulfopropyl methacrylate and their salts, and 2-acrylamido-2-methylpropanesulfonic acid and its salts; alkylated diphenyl ether disulfonates, sodium dodecylbenzene sulfonate and sodium sulfosuccinate dihexyl esters, sodium salts of alkyl sulfonates, ethoxylated alkylphenols and ethoxylated alcohols; and fatty alcohol (poly)ether sulfates. The presence of anionic surfactants during polymerization may be beneficial in supporting process stability and latex stability.

[0054] Various protective colloids may be used in place of or as a supplement to the surfactants described above. Suitable colloids include polyhydroxy compounds such as partially acetylated polyvinyl alcohol, casein, hydroxyethyl starch, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, polysaccharides and degraded polysaccharides, polyethylene glycol, and gum arabic. Preferred protective colloids are carboxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose. Typically, these protective colloids are used in amounts of 0-10, preferably 0-5, more preferably 0-2 parts by weight, based on the total weight of the monomers. The amount of protective colloid includes all values ​​and sub-values ​​therebetween, particularly including 1, 2, 3, 4, 5, 6, 7, 8, and 9% by weight, based on the total weight of the monomers.

[0055] It is generally recommended to conduct emulsion polymerization in the presence of additional buffers and chelating agents. Suitable substances are, for example, alkali metal carbonates and bicarbonates, alkali metal phosphates and pyrophosphates (buffers), and alkali metal salts of ethylenediaminetetraacetic acid (EDTA) or hydroxy-2-ethylenediaminetriacetic acid (HEEDTA) as chelating agents. The amounts of buffers and chelating agents are typically 0.001–1.0% by weight, based on the total amount of monomers.

[0056] Furthermore, the use of chain transfer agents (regulators) in emulsion polymerization can be advantageous. Typical agents are, for example, organosulfur compounds such as thioesters, 2-mercaptoethanol, 3-mercaptopropionic acid, isooctyl 3-mercaptopropionate, and C1-C12-methyl-2-methyl-2-ethylhexylene. 12 Alkyl mercaptan, preferably n-dodecyl mercaptan and tert-dodecyl mercaptan. If present, the amount of chain transfer agent is typically 0.05-3.0% by weight, preferably 0.2-2.0% by weight, based on the total weight of the monomers used.

[0057] Polymer latex:

[0058] The polymer latex of the present invention is prepared by aqueous emulsion polymerization using a monomer mixture as described above. If a nonionic surfactant, including the preferred surfactant, is not already used in sufficient quantity in the emulsion polymerization, it can be added to the polymer latex obtained by emulsion polymerization to provide the required amount (including the preferred amount) of the nonionic surfactant as described above.

[0059] To prepare the polymer latex of the present invention, various other additives and components can be added. Such additives include, for example, defoamers, wetting agents, thickeners, plasticizers, fillers, pigments, dispersants, fluorescent whitening agents, antioxidants, biocides, and metal chelating agents. Known defoamers include silicone oil and acetylenic glycol. Commonly known wetting agents include alkylphenol ethoxylates, alkali metal salts of dialkyl sulfosuccinate, acetylenic glycol, and alkali metal alkyl sulfates. Typical thickeners include polyacrylates, polyacrylamide, xanthan gum, modified cellulose, micron or nanocellulose fibers, polyurethane-type associative thickeners, or particulate thickeners such as silica and clay. Typical plasticizers include mineral oil, liquid polybutene, liquid polyacrylates, polyalkylene glycols such as polypropylene glycol or polybutane glycol, carboxylic esters such as alkyl esters of adipic acid, citric acid, phthalic acid, terephthalic acid, isophthalic acid, or trimellitic acid, and lanolin. Titanium dioxide (TiO2), calcium carbonate, and clay are commonly used fillers.

[0060] Building materials:

[0061] The polymer latex of the present invention can be used in building materials, particularly in applications where the solidification behavior of building materials may be affected by the polymer latex of the present invention.

[0062] The polymer latex of the present invention is particularly suitable for imparting an improved performance balance to building materials, preferably cement compositions. The cement compositions of the present invention may be selected from concrete, cement-based building materials such as mortar, tile adhesives or cement-based interface agents, and mortars such as bricklaying mortar, gypsum mortar, repair mortar, waterproof mortar, self-leveling mortar, exterior wall insulation bonding mortar, decorative mortar, thermal insulation mortar or flooring mortar.

[0063] The polymer used in these cement compositions is in a weight ratio of 0.02 to 0.4 to cement, primarily 0.05 to 0.2.

[0064] Depending on the intended end use, cement compositions may contain conventional components present in conventional amounts in individual cement compositions.

[0065] Besides water, typical compounds used in such cementitious systems include ordinary Portland cement, special Portland cement, high-alumina cement and blended cement, fine aggregates and coarse aggregates such as river sand, gravel, crushed sand and stone, silica sand and fly ash. Pigments can be added to obtain the desired color. Natural or synthetic glass fibers, carbon fibers and metal fibers can be added to enhance the cemented system. Additives can be added to adjust processing or mechanical properties. Examples include plasticizers or superplasticizers, flow agents, accelerators, retarders, defoamers, and air-entraining agents.

[0066] Other suitable applications of the polymer latex of the present invention are as filler materials for bricks, glass or metals.

[0067] The present invention will now be described in more detail with reference to the following embodiments. Example

[0068] The polymer latex compositions used in the examples and comparative examples were prepared by free radical emulsion polymerization combining an initial feed and a final feed. The initial feed consisted of 1.2 parts by weight (pphm) of polystyrene seeds with an average particle size of 36 nm based on total monomers, water (30 pphm), and HEEDTA (0.05 pphm) as a complexing agent. The initial feed was heated to 85°C with continuous stirring, and polymerization was initiated by starting with an ammonium persulfate (1 pphm). The temperature was maintained constant at 85°C. Ten minutes after the start of the persulfate feed, the monomers shown in Table 1, anionic surfactant (0.5 pphm of C14), and other components were added over a 6-hour period. 13 -C 15 Alkyl aryl sulfonate, 0.8 parts of tert-dodecyl mercaptan as a chain transfer agent, and water were added to the reactor at a constant feed rate. Post-activation with 0.25 pphm of ammonium persulfate was then initiated to reduce residual monomer and continued for 3 hours. The product was cooled to ambient temperature, sieved through a 50 μm mesh filter cloth, and the pH was adjusted to 7.5 using a 10% sodium hydroxide aqueous solution. The nonionic surfactants shown in Table 1 were then added and homogenized for 5 minutes. The final total solids content of the latex was adjusted to 50% by weight, and the final pH was adjusted to 8.5 using a sodium hydroxide solution.

[0069] The particle size of the latex was between 155 and 160 nm, as determined using a Mastersizer 2000, Malvern.

[0070] The latexes shown in Table 1 were used to prepare polymer-modified cement mortars. For each mortar, 900 g of CEMI 32.5 Portland cement (Schwenk) was mixed with 1350 g of standard sand according to EN196. Before use, 0.6% of the defoamer Tego Antifoam 2-89 (Evonik) was added to the latex. The test mortars were prepared by thoroughly mixing water and latex in a planetary mixer (Hobart N50) equipped with agitator blades at 140 rpm for 1 minute and then at 280 rpm for 1 minute, with a polymer-cement ratio of 0.075 (dry-dry) and a water-cement ratio of 0.38 (total 342 g water and 67.5 g polymer).

[0071] The mortar density was determined according to DIN EN 196-1:2016-11, the slump performance was determined according to DIN EN 1015-3:200-5 immediately after mixing and at 20, 40 and 60 minutes after mixing, and the compressive and flexural strengths were determined according to DIN EN 196-1:2016-11 after 48 hours, 7 days and 28 days.

[0072] The target value is:

[0073] Mortar density >2g / mL. Immediate collapse test: >16cm, after 20 minutes: >14cm, after 40 minutes: >13cm, after 60 minutes: >12cm. Compressive strength: after 48 hours: >4.5MPa, after 7 days: >6MPa, after 28 days: >8.5MPa. Flexural strength: after 48 hours: >18MPa, after 7 days: >25MPa, after 28 days: >35MPa.

[0074] The results are listed in Table 2.

[0075]

[0076]

Claims

1. A polymer latex obtained by aqueous emulsion polymerization of a mixture of olefinically unsaturated monomers, wherein the mixture of olefinically unsaturated monomers comprises a) A vinyl aromatic compound, in an amount of 24-70% by weight based on the total weight of the olefinically unsaturated monomers, wherein the vinyl aromatic compound is selected from styrene. -Methylstyrene, 4-methylstyrene -Chlorostyrene, 4-chlorostyrene, divinylbenzene, 4-methoxy-3-methylstyrene, 3,4-dimethyl- -Methylstyrene and their combinations; b) Conjugated dienes, in an amount of 16-45% by weight based on the total weight of the olefinically unsaturated monomers, wherein the conjugated dienes are selected from 1,3-butadiene, 2-chloro-1,3-butadiene, isoprene, conjugated straight-chain and branched pentadiene and hexadiene, and combinations thereof. c) A hydroxyalkyl ester of an olefinic unsaturated acid, wherein the amount is 2-10% by weight based on the total weight of the monomers, wherein the hydroxyalkyl ester of the olefinic unsaturated acid is selected from hydroxyalkyl acrylate and hydroxyalkyl methacrylate monomers based on ethylene oxide, propylene oxide and higher alkyl oxides or mixtures thereof; and d) An olefinically unsaturated carboxylic acid or a salt thereof, in an amount of 0-0.15% by weight based on the total weight of the monomers, wherein the olefinically unsaturated carboxylic acid or a salt thereof is selected from the group consisting of monocarboxylic and dicarboxylic acid monomers and their anhydrides, polycarboxylic acid esters, and their salts. The vinyl aromatic compound to conjugated diene has a weight ratio of at least 1.3:1, and the polymer latex contains 2-10% by weight of a nonionic surfactant having an HLB of 17-19, based on the total weight of the monomers.

2. The polymer latex of claim 1, wherein the vinyl aromatic compound is styrene.

3. The polymer latex of claim 1 or 2, wherein the vinyl aromatic compound is present in the monomer mixture in an amount of 38-65% by weight, based on the total weight of the olefinically unsaturated monomers.

4. The polymer latex of claim 1 or 2, wherein the conjugated diene is 1,3-butadiene.

5. The polymer latex of claim 1 or 2, wherein the conjugated diene is present in the monomer mixture in an amount of 24-39% by weight, based on the total weight of the olefinically unsaturated monomers.

6. The polymer latex of claim 1 or 2, wherein the hydroxyalkyl ester of the olefinic unsaturated acid is selected from 2-hydroxyethyl (meth)acrylate and 2-hydroxypropyl (meth)acrylate.

7. The polymer latex of claim 1 or 2, wherein the hydroxyalkyl ester of the olefinic unsaturated acid is present in the monomer mixture in an amount of 2-9% by weight, based on the total weight of the olefinic unsaturated monomers.

8. The polymer latex of claim 1 or 2, wherein the monomer mixture comprises up to 0.1% by weight of an olefinically unsaturated carboxylic acid and its salt.

9. The polymer latex of claim 1 or 2, wherein the monomer mixture further comprises e) an olefinic unsaturated monomer that is copolymerizable with monomers a)-d) and is different from monomers a)-d).

10. The polymer latex of claim 9, wherein the olefinically unsaturated monomer (e) is selected from: e1) Alkenyl unsaturated sulfonic acid; e2) C1-C20 alkyl esters of acrylic acid or methacrylic acid; and e3) Alkenyl bond unsaturated nitrile compounds.

11. The polymer latex of claim 1 or 2, wherein the nonionic surfactant is selected from alkyl ethoxylates, alkylphenol ethoxylates, fatty acid ethoxylates, ethylene glycol-propylene glycol block copolymers or tristyrylphenol ethoxylates, and / or the nonionic surfactant has an HLB value of 17 to 18.5, and / or the nonionic surfactant is present in the polymer latex in an amount of 2-9% by weight, based on the total weight of the olefinically unsaturated monomers.

12. The polymer latex of claim 1 or 2, further comprising an anionic surfactant.

13. The polymer latex of claim 1 or 2, wherein the polymer latex does not contain core / shell particles.

14. A building material comprising the polymer latex of any one of claims 1-13.

15. Use of the polymer latex according to any one of claims 1-13 in building materials.

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