CN111349190A

CN111349190A - Aqueous polymer emulsion, preparation method and application thereof

Info

Publication number: CN111349190A
Application number: CN201911325514.3A
Authority: CN
Inventors: 孙丽超; 曾重; 李真真; 周娟; 徐双双
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2018-12-21
Filing date: 2019-12-20
Publication date: 2020-06-30
Anticipated expiration: 2039-12-20
Also published as: CN111349190B

Abstract

The invention relates to aqueous polymer emulsions, to a process for their preparation and to their use. The aqueous multistage polymer emulsion comprises a multistage polymer having a total calculated Fox Tg (Tg0) in the range of-15 to +5 ℃, a difference (Δ Tg) between the calculated Fox Tg (Tg2) of the second stage polymer and the Fox Tg (Tg1) of the first stage polymer of more than 10 ℃, and a weight ratio of the first stage polymer to the second stage polymer in the range of 95:5 to 30:70, based on the total amount of monomers used for each stage polymerization. The emulsion has balanced Low Temperature Film Flexibility (LTFF), DPUR and acid resistance properties.

Description

Aqueous polymer emulsion, preparation method and application thereof

Technical Field

The present invention relates to aqueous multistage polymer emulsions, to a process for their preparation and to their use. In particular, the present invention relates to multistage polymer emulsions suitable for coating applications. The invention also discloses a preparation method and application thereof.

Background

Aqueous polymer emulsions are used in many fields, for example in coatings, adhesives, etc. When applied in coatings, especially exterior wall coatings, the polymeric material is exposed to the atmosphere and subjected to weathering processes, wherein the material dissolves, wears or breaks into smaller and smaller pieces when in contact with acids, bases, dust, etc. Thus, it is desirable that the aqueous polymer emulsion may have excellent performance against weathering processes. In addition, the flexibility of the film, especially Low Temperature Film Flexibility (LTFF), is also an important property of the coating, which is typically produced from the emulsions used in the coating.

Many solutions have been proposed to impart LTFF, acid resistance and stain resistance (DPUR) to coatings. Also, emphasis has been placed on aqueous emulsions as the main component in coating formulations. In general, stain resistance requires a hard emulsion polymer, while flexibility of the film requires a soft emulsion polymer.

CN1256295A discloses a method of balancing DPUR and flexibility by using a multistage polymer emulsion. The multistage polymer comprises both hard segments and soft segments in the final polymer. However, to address DUPR performance, the flexibility of the membrane is sacrificed to some extent.

JP2003147150A discloses an aqueous polymer dispersion capable of forming a coating film having low-temperature flexibility and a method for producing the same. It constructs a film of a two-layer structure, wherein the a layer comprises a polymer having a carboxyl group with a measured Tg of-15 ℃ and the B layer comprises a polymer with a measured Tg of 30-150 ℃. After the layer a is formed, the layer B is formed by polymerization. This method requires two-step film formation and the use of two different polymers, and is therefore not ideal for exterior wall coatings.

CN106118175A discloses an acid and corrosion resistant coating. The coating comprises a fluorinated acrylate emulsion and polydimethyldiallylammonium chloride (polydadmac). In this application, no antacid data are provided. Also, the use of fluorinated acrylate emulsions will increase the overall cost of the coating.

Accordingly, there is still a need to develop an emulsion system more suitable for coatings, especially exterior wall coatings, which requires balanced Low Temperature Film Flexibility (LTFF), DPUR and acid resistance properties.

Disclosure of Invention

It is an object of the present invention to provide aqueous multistage polymer emulsions having balanced Low Temperature Film Flexibility (LTFF), DPUR and acid resistance properties. The aqueous multistage polymer emulsion comprises a polymer having a total calculated FoxTg (Tg0) in the range of-15 ℃ to +5 ℃, a difference (Δ Tg) between the calculated Fox Tg (Tg2) of the second stage polymer and the Fox Tg (Tg1) of the first stage polymer of greater than 10 ℃, and a weight ratio of the first stage polymer to the second stage polymer in the range of 95:5 to 30:70, based on the total amount of monomers used for each stage polymerization.

It is another object of the present invention to provide a method for preparing the same. The aqueous multistage polymer emulsion is synthesized by multistage emulsion polymerization.

A third object of the present invention is to provide the use of an aqueous multistage polymer emulsion, i.e. a coating, especially an architectural coating.

Detailed Description

Unless otherwise defined, all terms/terms of art/nomenclature used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

The terms "a", "an" and "the" when used in defining a term include both the plural and singular forms of that term.

The term "polymer" as used herein includes both homopolymers, i.e. polymers prepared from a single reactive compound, and copolymers, i.e. polymers prepared by reaction of at least two monomeric compounds which are reactive towards polymer formation.

The term "multistage emulsion polymer" means a polymer that includes at least a first stage polymer formed in a first emulsion polymerization process, and includes at least a second stage polymer that is subsequently polymerized in a second emulsion polymerization process.

The name (meth) acrylate and similar names are used herein as abbreviations for "acrylate and/or methacrylate".

All percentages and ratios are expressed as weight percentages and weight ratios, unless otherwise indicated.

The present invention relates to aqueous multistage polymer emulsions having balanced Low Temperature Film Flexibility (LTFF), DPUR and acid resistance properties. The aqueous multistage polymer emulsion comprises a multistage polymer having a total calculated Fox Tg (Tg0) in the range of-15 ℃ to +5 ℃, a difference (Δ Tg) between the calculated Fox Tg (Tg2) of the second stage polymer and the Fox Tg (Tg1) of the first stage polymer of greater than 10 ℃, and a weight ratio of the first stage polymer to the second stage polymer in the range of 95:5 to 30:70, based on the total amount of monomers used for each stage polymerization.

In a preferred embodiment, the total calculated Fox Tg (Tg0) of the aqueous multistage polymer emulsion is in the range of-10 ℃ to +5 ℃, the difference (Δ Tg) between the calculated Fox Tg (Tg2) of the second stage polymer and the Fox Tg (Tg1) of the first stage polymer is more than 10 ℃, and the weight ratio of the first stage polymer to the second stage polymer is in the range of 90:10 to 40:60, based on the total amount of monomers used for each stage polymerization.

In a more preferred embodiment, the total calculated Fox Tg (Tg0) of the aqueous multistage polymer emulsion is in the range of-10 ℃ to 0 ℃, the difference (Δ Tg) between the calculated Fox Tg (Tg2) of the second stage polymer and the Fox Tg (Tg1) of the first stage polymer is more than 15 ℃, and the weight ratio of the first stage polymer to the second stage polymer is in the range of 90:10 to 50:50, based on the total amount of monomers used for each stage polymerization.

In the context of the present application, the term Fox Tg refers to the glass transition temperature (Tg) calculated according to the following Fox equation disclosed in t.g. Fox, Bulletin of the american physical Society, volume 1, phase 3, page 123 (1956):

1/Tg＝W₁/Tg₁+W₂/Tg₂+...+W_n/Tg_n

wherein,

W₁、W₂、…W_nare mass fractions of monomers 1,2,. n, respectively, and

Tg₁、Tg₂、…Tg_nglass transition temperatures in kelvin for homopolymers of monomers 1,2,. n, respectively.

The homopolymer Tg values of most monomers are known and are listed, for example, in Ullmann's Ecylopedia of Industrial Chemistry, volume 5, column A21, page 169, VCH Weinheim, 1992. Other sources of glass transition temperatures for homopolymers include, for example, j.brandrup, e.h.immergut, Polymer Handbook, first edition, j.wiley, New York 1966, second edition, j.wiley, New York 1975, and third edition, j.wiley, New York 1989.

The aqueous multistage polymer emulsion comprises one or more multistage polymers in an aqueous medium. There is no particular limitation on the monomers used to prepare the polymer. However, the resulting polymer should have an overall Fox Tg in the range of-15 ℃ to 5 ℃, preferably-10 ℃ to 5 ℃ and most preferably-10 ℃ to 0 ℃. It is also necessary that the weight ratio of the first stage polymer to the second stage polymer be in the range of 95:5 to 30:70, preferably 90:10 to 40:60 and most preferably 90:10 to 50:50, based on the total amount of monomers used in each stage polymerization. In addition, the difference (Δ Tg) between the calculated Fox Tg of the second stage polymer (Tg2) and the Fox Tg of the first stage polymer (Tg1) must also be maintained above 10 ℃ and preferably above 15 ℃.

The monomers used for the first stage polymer and the second stage polymer may each be independently selected from monomers known in the coating art to be useful in preparing aqueous polymer dispersions. The types of monomers used for the first stage polymer and the second stage polymer can be the same or different, so long as the resulting polymer can have a particular Tg as discussed above.

The monomers used for the first stage polymer and the second stage polymer may each independently comprise:

(A) at least one hydrophobic monoethylenically unsaturated monomer (a), the total amount of hydrophobic monoethylenically unsaturated monomers may be at least 80 wt.%, preferably at least 85 wt.%, more preferably at least 90 wt.%, most preferably at least 95 wt.%; and

(B) at least one hydrophilic monoethylenically unsaturated monomer (b), the total amount of hydrophilic monoethylenically unsaturated monomers may be at least 0.1% and not more than 20% by weight, preferably not more than 15% by weight, more preferably not more than 10% by weight, most preferably not more than 5% by weight;

each based on the total weight of monomers used to make the respective first stage and second stage polymers.

The at least one hydrophobic monoethylenically unsaturated monomer (a) may be selected from (meth) acrylate monomers, (meth) acrylonitrile monomers, styrene monomers, vinyl alkanoate monomers, and monoethylenically unsaturated dicarboxylate and tricarboxylate monomers.

In particular, the (meth) acrylate monomer may be (meth) acrylic acid C₁-C₁₉Alkyl esters, such as but not limited to: methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, n-octyl (meth) acrylate, n-decyl (meth) acrylate, n-dodecyl (meth) acrylateAlkyl esters (i.e., lauryl (meth) acrylate), tetradecyl (meth) acrylate, oleyl (meth) acrylate, palmityl (meth) acrylate, stearyl (meth) acrylate, isobornyl (meth) acrylate, benzyl (meth) acrylate, phenyl (meth) acrylate, and mixtures thereof.

In particular, the styrene monomer may be unsubstituted styrene or C1-C6-alkyl substituted styrene such as, but not limited to, styrene, α -methylstyrene, o-methylstyrene, m-and p-methylstyrene, o-ethylstyrene, m-and p-ethylstyrene, o-dimethylstyrene, p-dimethylstyrene, o-diethylstyrene, p-diethylstyrene, isopropylstyrene, o-methyl-p-isopropylstyrene, or any mixture thereof.

In particular, the vinyl alkanoate monomer may be C₂-C₁₁Vinyl esters of alkanoic acids, such as but not limited to: vinyl acetate, vinyl propionate, vinyl butyrate, vinyl valerate, vinyl hexanoate, vinyl versatate, or mixtures thereof.

In addition, the monoethylenically unsaturated dicarboxylate ester monomers and monoethylenically unsaturated tricarboxylate ester monomers may be full esters of monoethylenically unsaturated dicarboxylic acids and monoethylenically unsaturated tricarboxylic acids, such as, but not limited to: diethyl maleate, dimethyl fumarate, ethyl methyl itaconate, or any mixture thereof.

In a preferred embodiment of the present invention, one or more (meth) acrylic acids C₁-C₁₂Alkyl esters, such as methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate and 2-ethylhexyl (meth) acrylate, styrene, or mixtures thereof, are selected as the at least one hydrophobic monoethylenically unsaturated monomer (a).

The at least one hydrophilic monoethylenically unsaturated monomer (b) may be a monoethylenically unsaturated monomer having at least one functional group selected from the group consisting of carboxyl, carboxylic anhydride, sulfonic acid, phosphoric acid, hydroxyl, and amide.

In particular, hydrophilic monoethylenically unsaturated monomers (b) include, but are not limited to: monoethylenically unsaturated carboxylic acids such as (meth) acrylic acid, itaconic acid, fumaric acid, citraconic acid, sorbic acid, cinnamic acid, glutaconic acid, and maleic acid; monoethylenically unsaturated carboxylic acid anhydrides such as itaconic anhydride, fumaric anhydride, citraconic anhydride, sorbic anhydride, cinnamic anhydride, glutaric anhydride, and maleic anhydride; monoethylenically unsaturated amides, especially N-alkylolamides, such as (meth) acrylamide, N-methylol (meth) acrylamide, 2-hydroxyethyl (meth) acrylamide; and hydroxyalkyl esters of monoethylenically unsaturated carboxylic acids, such as hydroxyethyl (meth) acrylate and hydroxypropyl (meth) acrylate.

In a preferred embodiment of the present invention, acrylic acid, methacrylic acid, itaconic acid, acrylamide, methacrylamide, or mixtures thereof are preferred as the at least one hydrophilic monoethylenically unsaturated monomer (b).

The monomer of the present invention may further comprise one or more crosslinking monomers (c). The crosslinking monomer may be selected from diisocyanates or polyisocyanates, polyaziridines, polycarbodiimides, poly

Oxazolines, glyoxals, triols, epoxy molecules, organosilanes, carbamates, diamines and triamines, hydrazides, carbodiimides and polyethylenically unsaturated monomers. In the present invention, suitable crosslinking monomers include, but are not limited to: glycidyl (meth) acrylate, N-methylol (meth) acrylamide, (isobutoxymethyl) acrylamide, vinyltrialkoxysilane (e.g., vinyltrimethoxysilane); alkylvinyldialkoxysilanes (e.g., dimethoxymethylvinylsilane), (meth) acryloxyalkyltrialkoxysilanes (e.g., (meth) acryloxyethyltrimethoxysilane, (3-acryloxypropyl) trimethoxysilane, and (3-methacryloxypropyl) trimethoxysilane), allyl methacrylate, diallyl phthalate, 1, 4-butanediol dimethacrylate, 1, 2-ethylene glycol dimethacrylate, 1, 6-hexanediol diacrylate, divinylbenzene, or any mixture thereof.

The amount of crosslinking agent that may be added is not more than 10% by weight, preferably not more than 8% by weight, more preferably not more than 5% by weight, based on the total weight of all monomers used for polymer synthesis.

The calculated Fox Tg of the polymer can be controlled by varying the weight ratio of hard and soft monomers applied to the polymer synthesis. In the present invention, a monomer is considered a hard monomer if it can produce a homopolymer with a calculated Fox Tg in excess of 10 ℃ and a soft monomer otherwise.

Soft monomers may include, but are not limited to: methyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, nonyl acrylate, ethyl acrylate, decyl methacrylate, isodecyl methacrylate, hexyl (meth) acrylate, cyclohexyl acrylate, dodecyl (meth) acrylate, octyl methacrylate, propyl acrylate, ethylene adipate, diethyl fumarate, 1, 4-butadiene, 1-pentene, di-2-ethylhexyl maleate, di-2-ethylhexyl fumarate, and mixtures thereof. In a preferred embodiment, alkyl acrylates having 4 to 12 carbon atoms in the alkyl group, such as n-butyl acrylate and 2-ethylhexyl acrylate, are used as soft monomers.

Hard monomers may include, but are not limited to: methyl methacrylate, tert-butyl acrylate, benzyl methacrylate, ethyl methacrylate, acrylamide, acrylic acid, methacrylic acid, itaconic acid, fumaric acid, citraconic acid, sorbic acid, cinnamic acid, glutaric and maleic vinyl alcohols, vinyl acetate, vinyl butyrate, vinyl formate, vinyl valerate, vinyl versatate, styrene, C1-C6-alkyl-substituted styrene. In a preferred embodiment, acrylic acid, methacrylic acid, methyl (meth) acrylate, styrene, acrylamide, methacrylamide, or mixtures thereof are used as hard monomers.

It is essential that the total calculated Fox Tg (Tg0) of the emulsion polymer be in the range of-15 deg.C to +5 deg.C, preferably-10 deg.C to +5 deg.C and most preferably-10 deg.C to 0 deg.C. A high total Fox Tg of the polymer reduces film flexibility at low temperatures, while a too low total Fox Tg reduces DPUR. Acid resistance performance can also be affected by Fox Tg.

It is also necessary to control the weight ratio of the first stage polymer to the second stage polymer and the difference (Δ Tg) between the calculated Fox Tg (Tg2) of the second stage polymer and the Fox Tg (Tg1) of the first stage polymer. In the present invention, the weight ratio of the first-stage polymer to the second-stage polymer is in the range of 95:5 to 30:70, preferably 90:10 to 40:60 and most preferably 90:10 to 50:50, based on the total amount of monomers used in each stage polymerization. In the present invention, the Δ Tg is preferably 10 ℃ or higher, more preferably 15 ℃ or higher.

The aqueous multistage polymer emulsion of the present invention may be prepared by a multistage polymerization process comprising polymerization of a first stage monomer to produce a first stage polymer, and subsequent polymerization of a second stage monomer to produce a second stage polymer. Multistage polymerization techniques well known in the art can be used to prepare the aqueous multistage copolymer dispersions of the present invention, for example the processes disclosed in US2728804A, US20170096575a1, US20170355802a1 and the like.

The emulsion polymerization can be carried out as a batch operation or as a feed process (i.e., the reaction mixture is fed to the reactor in a staged or gradient procedure). The feed process is the preferred process. In this process, a small portion of the reaction mixture of the first stage monomers may be introduced as an initial charge and heated to a polymerization temperature that will generally produce a polymer seed. The remainder of the polymerization mixture of the first stage polymer is then supplied to the reactor, typically by means of two or more spatially separated feed streams. After the feed is complete, the reaction is allowed to proceed for a further 10 to 30 minutes and, optionally, the mixture is subsequently fully or partially neutralized. After completion of the first-stage polymerization, the polymerization mixture of the second-stage monomers was supplied to the reactor in the same manner as described above. After the feed was complete, the polymerization was held for a further 30 to 90 minutes. Thereafter, the reaction mixture may be treated with an oxidizing agent, a neutralizing agent, or the like.

In a multistage polymerization process, most surfactants known to those skilled in the art can be used. The surfactant used according to the present invention may be a non-reactive surfactant, a reactive surfactant, or a combination thereof. The surfactant may be formulated with the monomer and fed to the reactor of the reaction. Alternatively, the surfactant may be added to the reaction medium first, followed by the feed of monomer. The surfactant may be used in suitable amounts known to those skilled in the art (e.g., in a total amount of 0.1 to 6 wt%, based on the total weight of the monomers).

The surfactant may be a non-reactive anionic and/or nonionic surfactant. Suitable non-reactive anionic surfactants include, for example, but are not limited to: alkyl, aryl or alkylaryl sulfates, sulfonates or phosphates; an alkyl sulfonic acid; a sulfosuccinate salt; fatty alcohol ether sulfates and fatty acids. Suitable non-reactive nonionic surfactants include, for example, alcohol or phenol ethoxylates, such as polyoxyethylene alkylphenyl ethers.

The surfactant may also be a polymerizable surfactant, also referred to as a reactive surfactant, which contains at least one ethylenically unsaturated functional group. Suitable polymerizable surfactants include, for example, but are not limited to: allyl polyoxyalkylene ether sulfate such as sodium allyl polyoxyethylene alkyl ether sulfate; allyl alkyl succinate sulfonate; allyl ether hydroxypropane sulfonates, such as the sodium salt; polyoxyethylene styrenated phenyl ether sulfates, e.g. ammonium salts, e.g. DKS

AR 1025 and DKS

AR 2020; polyoxyethylene alkyl phenyl ether ammonium sulfate salt; polyoxyethylene allyloxy nonylphenoxypropyl ether, and compositions such as

Acrylic acid phosphates of PAM100 or the like, e.g. PAM

Phosphorus acrylate such as PAM 200Acid esters, and the like.

Emulsion polymerization can be carried out in the presence of various common initiation systems, including but not limited to thermal initiators or redox initiators. The amount of initiator used is generally not more than 10% by weight, preferably from 0.02 to 5% by weight, more preferably from 0.1 to 1.5% by weight, based on the total weight of the two-stage monomers.

Thermal initiators are generally used, such as peroxides, persulfates, and azo compounds. Peroxides that can be used include, but are not limited to: inorganic peroxides, such as hydrogen peroxide or peroxydisulfate; or organic peroxides, for example tert-butyl hydroperoxide, p-menthyl hydroperoxide or cumyl hydroperoxide, tert-butyl perpivalate and dialkyl peroxides or diaryl peroxides, such as di-tert-butyl or dicumyl peroxide. Azo compounds that can be used include, but are not limited to: 2,2 '-azobis (isobutyronitrile), 2' -azobis (2, 4-dimethylvaleronitrile). Among them, Sodium Persulfate (SPS), potassium persulfate (KPS), Ammonium Persulfate (APS), 2 '-azobis (amidinopropyl) dihydrochloride (AIBA, V-50. TM.), and 4,4' -azobis (4-cyanovaleric acid) (ACVA, V501) are preferable as the thermal initiator.

Redox initiators generally comprise an oxidizing agent and a reducing agent. Suitable oxidizing agents include the peroxides described above. Suitable reducing agents may be alkali metal sulfites, such as potassium sulfite and/or sodium sulfite; or alkali metal bisulfites such as potassium bisulfite and/or sodium bisulfite. Preferred redox initiators include oxidizing agents selected from t-butyl hydroperoxide and hydrogen peroxide, and reducing agents selected from ascorbic acid, sodium formaldehyde sulfoxylate, sodium acetone bisulfite and sodium metabisulfite (sodium bisulfite).

The polymerization may be carried out and maintained at a temperature below 100 c throughout the reaction. Preferably, the polymerization is carried out at a temperature between 60 ℃ and 95 ℃. Depending on the various polymerization conditions, the polymerization can be carried out for several hours, for example from 2 to 8 hours.

The organic base and/or inorganic base may be added to the polymerization system as a neutralizing agent during the polymerization process or after the completion of the process. Suitable neutralizing agents include, but are not limited to: an inorganic base, such as ammonia, sodium/potassium hydroxide, sodium/potassium carbonate, or any combination thereof. Organic bases such as dimethylamine, diethylamine, triethylamine, monoethanolamine, triethanolamine, or mixtures thereof can also be used as neutralizing agents. Among them, sodium hydroxide, ammonia, dimethylaminoethanol, 2-amino-2-methyl-1-propanol, or any mixture thereof is preferable as the neutralizer that can be used in the polymerization process. After addition of the neutralizing agent, the pH of the final polymer emulsion should be in the range of 6.0 to 10.0, preferably in the range of 7.0 to 9.5, more preferably in the range of 7.0 to 9.0.

The mean particle diameter of the polymer particles dispersed in the aqueous dispersion is preferably less than 300nm, in particular less than 250 nm. Particularly preferably, the average particle size lies between 50 and 200 nm.

The solids content of the aqueous multistage copolymer dispersion of the present invention may range from 10 to 70 wt. -%, preferably from 20 to 60 wt. -%, more preferably from 30 to 60 wt. -% and most preferably from 40 to 60 wt. -%.

The aqueous multistage polymer emulsions of the present invention may be formulated with pigments, emulsifiers, buffers, neutralizers, rheology modifiers, humectants, wetting agents, biocides, plasticizers, defoamers, colorants, waxes, antioxidants, and other materials used to prepare coating compositions. The formulation is not particularly limited, and commonly used formulations known to those skilled in the art, such as those disclosed in US20090149591a1, US20140235752a1, WO2012021826a2, and the like, may be applied. Suitable pigments include, but are not limited to, zinc oxide, antimony oxide, zirconium oxide, titanium dioxide, and Ropaque^TMOpaque polymers (Rohm and haas co., philiadelphia, pa., USA). Suitable emulsifiers include, but are not limited to: alkali metal or ammonium alkyl sulfates, alkyl sulfonic acids, fatty acids, nonylphenol ethoxylates, sodium dodecylbenzenesulfonate, known under the trade name Triton^TMOr Igepal^TMOr Rhodapon^TMThose sold. Suitable rheology modifiers include, but are not limited to: starch and cellulose derivatives, alkali swellable acrylic thickeners, materials under the trade name ACRYSOL. Suitable anti-foaming agents include, but are not limited to: the name of the commodity is

Colloid and

And

the material of (1). Suitable biocides include, but are not limited to: under the trade name Nuosept^TMAnd

the compound of (1).

The aqueous multistage polymer emulsions of the present invention can be formulated into coating compositions by various methods known to those skilled in the art. The preparation of the coating composition is not particularly preferred. For example, a suitable amount of pigment is dispersed in an aqueous medium in a suitable mixer at high shear rates. The aqueous multistage polymer dispersion is then added to the dispersion by continuous feeding. At the same time, other necessary materials are also fed into the mixer, which may include emulsifiers, rheology modifiers, defoamers, plasticizers, colorants, waxes, antioxidants, and the like.

The invention will be further illustrated and exemplified in the examples, but is not limited to the embodiments described in the examples.

Examples

Description of commercially available materials used in the following examples:

RS-710: dispersant, phosphate, from Solvay (hereinafter referred to as RS-710).

PAM 100: reactive surfactants, phosphate methacrylate derivatives, from Solvay (hereinafter referred to as PAM 100).

FF6M reducing agent, sodium salt of an organic sulfinic acid derivative from Br ü ggemann chemical (hereinafter FF 6M).

DB 45: diphenyl ether disulfonate anionic surfactant from Pilot chemical company (hereinafter DB 45).

24T: phosphate ester surfactant from BASF.

LDBS 23: alkylbenzene sulfonate surfactant from BASF.

ADEKA Resoap SR-1025: the reaction product of a surfactant, ethylene oxide [ (2-propenyloxy) methyl ] with a C10-14 branched alcohol, ethylene oxide and sulfamic acid, from ADEKA CORPORATION, Japan (hereinafter referred to as SR 1025).

All experiments described below were carried out at a temperature of 20 ℃ unless otherwise stated.

Example 1 (invention):

the first stage mixture pre-emulsion was prepared by the following procedure: 13.6g SR1025, 8.4gRS710, 5.2g PAM100, 763.2g Butyl Acrylate (BA), 252.2g Styrene (ST), 16.8g Acrylic Acid (AA), 44.2g acrylamide solution (Am, 30 wt% aqueous solution) and 518.7g deionized water were mixed in a vessel and then emulsified by stirring at 500rpm for 10 minutes using a magnetic stir bar.

The pre-emulsion of the second stage mixture was prepared by the following procedure: 62.5g Butyl Acrylate (BA), 150.2g Styrene (ST), 26.4g Glycidyl Methacrylate (GMA), 7.2g SR1025, 4.5g RS710 and 157.9g deionized water were mixed in a vessel and then emulsified by stirring at 500rpm for 10 minutes using a magnetic stir bar.

5.25g SR1025 and 401.4g water were charged to a four-liter, multi-necked flask equipped with a mechanical stirring device under a nitrogen atmosphere. The mixture was heated to a temperature of 90 ℃ under a nitrogen atmosphere and, unless otherwise stated, this condition was maintained in the following operation. 71.4g of a pre-emulsion of the first stage monomer (first portion) and 20.8g of sodium persulfate (SPS, 4.1% by weight in water) were added in parallel to the flask with stirring over 2 minutes. Five minutes after the first portion was added, the remaining pre-emulsion of the first stage monomers was fed over 120 minutes. Then, the pre-emulsion of the second stage monomer was added over 30 minutes. Separately, once the addition of the second portion of the first stage monomers was started, a feed of 73.5g of SPS (4.1% by weight in water) was started for 150 minutes. After 30 minutes of completion of the SPS feed, the reaction temperature was lowered to 55 ℃ and 6.47g of ammonia solution (20% by weight aqueous solution) and 10.4g of NaOH solution (8% by weight aqueous solution) were added to neutralize the system. Then, 23.0g t-BHP (10 wt% aqueous solution) and 45.4g FF6M (10 wt% aqueous solution) were added in parallel over 90 minutes. After the feed of t-BHP and FF6M was complete, the reaction mixture was cooled to 20 ℃ and neutralized with aqueous NaOH to pH 8. Finally, biocide (2.7 g) was added

MV and 8.7g

MBS, all from THOR, Germany) was added to the mixture.

The resulting aqueous polymer emulsion had a pH of 8, a solids content of 49% by weight and a particle size of 156 nm.

Example 2 (invention):

a pre-emulsion of the first stage mixture was prepared by the following procedure: 7.5g of DB45, 8.4g of Maphos24T, 5.1g of PAM100, 64.3g of acrylamide solution (Am, 30% by weight aqueous solution), 16.8g of Acrylic Acid (AA), 606.8g of Butyl Acrylate (BA), 139.2g of Styrene (ST) and 514.3g of deionized water were mixed in a vessel and then emulsified by stirring at 500rpm for 10 minutes using a magnetic stir bar.

Pre-emulsion 2 was prepared by the following procedure: 4.0g of DB45, 4.5g of Maphos24T, 54.4g of acetoacetoxyethyl methacrylate (AAEMA), 214.2g of Butyl Acrylate (BA) and 257.7g of Styrene (ST) and 156.6g of deionized water were mixed in a vessel and then emulsified by stirring at 500rpm for 10 minutes using a magnetic stir bar.

Under the protection of nitrogen atmosphere, 5.7g

LDBS23, 0.33g of copper sulfate solution (0.1% by weight in water), and 398g of deionized water were charged into a four-liter, multi-necked flask equipped with a mechanical stirring device. The mixture was heated to a temperature of 90 ℃ under a nitrogen atmosphere and, unless otherwise stated, this condition was maintained in the following operation. 79.2g of a pre-emulsion of the first stage monomer (first part) and 20.7g of sodium persulfate (SPS, 4.1% by weight in water) were added in parallel to the flask with stirring over 2 minutes. Five minutes after the first portion was added, the remaining pre-emulsion of the first stage monomers was fed over 90 minutes. Then, the pre-emulsion of the second stage monomer was added over 60 minutes. Separately, once the addition of the second portion of the first stage monomers was started, a feed of 72.9g of SPS (4.1 wt% aqueous solution) was started, which feed lasted 150 minutes. After 30 minutes of completion of the SPS feed, the reaction temperature was lowered to 75 ℃ and 6.5g of an ammonia solution (20% by weight aqueous solution) was added to neutralize the system. Then, 7.7g t-BHP (10 wt% aqueous solution) and 9.8g sodium acetone bisulfite (SAB, 13 wt% aqueous solution) were added in parallel over 90 minutes. After the feeds of t-BHP and SAB were complete, the reaction mixture was cooled to 20 ℃ and neutralized with aqueous NaOH to pH 8. Finally, biocide (2.7 g) was added

MV and 8.7g

MBS, all from THOR, Germany) was added to the mixture.

The resulting aqueous polymer emulsion had a pH of 8, a solids content of 49% by weight and a particle size of 130 nm.

Example 3 (invention):

a pre-emulsion of the first stage mixture was prepared by the following procedure: 16.7g SR1025, 9.8gRS710, 5.1g PAM100, 45.7g acrylamide solution (Am, 30 wt% aqueous solution), 10.7g Acrylic Acid (AA), 19.4g Glycidyl Methacrylate (GMA), 632.7g Butyl Acrylate (BA), 343.7g Styrene (ST), and 524.6g deionized water were mixed in a vessel, and then emulsified with a magnetic stir bar for 10 minutes at 500 rpm.

The pre-emulsion of the second stage mixture was prepared by the following procedure: 1.5g SR1025, 7.0gRS710, 5.7g Acrylic Acid (AA), 16.3g Glycidyl Methacrylate (GMA), 192.7g Butyl Acrylate (BA), 35.2g Styrene (ST), and 159.7g deionized water were mixed in a vessel and then emulsified by stirring at 500rpm for 10 minutes using a magnetic stir bar.

5.3g SR1025 and 405.9g water were charged to a four liter, multi-necked flask equipped with a mechanical stirring device under a nitrogen atmosphere. The mixture was heated to a temperature of 90 ℃ under a nitrogen atmosphere and, unless otherwise stated, this condition was maintained in the following operation. 72.2g of a pre-emulsion of the first stage monomer (first part) and 21.1g of sodium persulfate (SPS, 4.1% by weight in water) were added in parallel to the flask over 2 minutes with stirring. Five minutes after the first portion was added, the remaining pre-emulsion of the first stage monomers was fed over 120 minutes. After the feed of the first stage monomer was completed, the reaction was kept as it was for 30 minutes. Then, the addition of the pre-emulsion of the second stage monomer was started and completed within 30 minutes. Separately, once the addition of the second portion of the first stage monomers was started, a feed of 74.3g of SPS (4.1% by weight in water) was started. The SPS feed was first continued for 120 minutes, then paused for 30 minutes, and then continued for another 30 minutes. After 30 minutes of completion of the SPS feed, the reaction temperature was lowered to 55 ℃ and 39.9g of NaOH solution (8% by weight aqueous solution) was added to neutralize the system. Then, 23.2g t-BHP (10 wt% aqueous solution) and 45.4g FF6M (10 wt% aqueous solution) were added in parallel over 90 minutes. After the feed of t-BHP and FF6M was complete, the reaction mixture was cooled to 20 ℃ and neutralized with aqueous NaOH solution topH 8. Finally, biocide (2.7 g) was added

MV and 8.7g

MBS, all from THOR, Germany) was added to the mixture.

The aqueous multistage polymer emulsion obtained had a pH of 8, a solids content of 47% by weight and a particle size of 150 nm.

Example 4 (invention):

a pre-emulsion of the first stage mixture was prepared by the following procedure: 16.6g SR1025, 0.08gRS710, 5.1g PAM100, 55.5g acrylamide solution (Am, 30 wt% aqueous solution), 12.0g Acrylic Acid (AA), 24.8g Glycidyl Methacrylate (GMA), 670.6g Butyl Acrylate (BA), 266.7g Styrene (ST), and 524.6g deionized water were mixed in a vessel, and then emulsified by stirring at 500rpm for 10 minutes using a magnetic stir bar.

The pre-emulsion of the second stage mixture was prepared by the following procedure: 1.0g SR1025, 6.4gRS710, 4.2g Acrylic Acid (AA), 18.7g Glycidyl Methacrylate (GMA), 105.7g Butyl Acrylate (BA), 150.5g Styrene (ST), and 159.7g deionized water were mixed in a vessel and then emulsified by stirring at 500rpm for 10 minutes using a magnetic stir bar.

5.3g SR1025 and 405.9g water were charged to a four liter, multi-necked flask equipped with a mechanical stirring device under a nitrogen atmosphere. The mixture was heated to a temperature of 90 ℃ under a nitrogen atmosphere and, unless otherwise stated, this condition was maintained in the following operation. 72.2g of a pre-emulsion of the first stage monomer (first part) and 21.1g of sodium persulfate (SPS, 4.1% by weight in water) were added in parallel to the flask over 2 minutes with stirring. Five minutes after the first portion was added, the remaining pre-emulsion of the first stage monomers was fed over 120 minutes. After the feed of the first stage monomer was completed, the reaction was kept as it was for 30 minutes. Then, the addition of the pre-emulsion of the second stage monomer was started and completed within 30 minutes. Separately, once the first addition is startedA second portion of the stage monomers, a feed of 74.3g of SPS (4.1% by weight in water) was started. The SPS feed was first continued for 120 minutes, then paused for 30 minutes, and then continued for another 30 minutes. After 30 minutes of completion of the SPS feed, the reaction temperature was lowered to 55 ℃ and 39.9g of NaOH solution (8% by weight aqueous solution) was added to neutralize the system. Then, 23.2g t-BHP (10 wt% aqueous solution) and 45.4g FF6M (10 wt% aqueous solution) were added in parallel over 90 minutes. After the feed of t-BHP and FF6M was complete, the reaction mixture was cooled to 20 ℃ and neutralized with aqueous NaOH to pH 9. Finally, biocide (2.7 g) was added

MV and 8.7g

MBS, all from THOR, Germany) was added to the mixture.

The resulting aqueous polymer emulsion had a pH of 9, a solids content of 48% by weight and a particle size of 156 nm.

Example 5 (invention):

a pre-emulsion of the first stage mixture was prepared by the following procedure: 13.4g SR1025, 8.4gRS710, 5.1g PAM100, 43.7g acrylamide solution (Am, 30 wt% aqueous solution), 16.7g Acrylic Acid (AA), 754.7g Butyl Acrylate (BA), 249.4g Styrene (ST), and 512.9g deionized water were mixed in a vessel and then emulsified by stirring at 500rpm for 10 minutes using a magnetic stir bar.

The pre-emulsion of the second stage mixture was prepared by the following procedure: 7.4g SR1025, 4.5gRS710, 54.2g acetoacetoxyethyl methacrylate, 61.8g Butyl Acrylate (BA), 148.6g Styrene (ST), and 156.2g deionized water were mixed in a vessel, and then emulsified by stirring at 500rpm for 10 minutes using a magnetic stir bar.

5.2g SR1025 and 396.9g water were charged to a four liter, multi-necked flask equipped with a mechanical stirring device under a nitrogen atmosphere. The mixture was heated to a temperature of 90 ℃ under a nitrogen atmosphere and, unless otherwise stated, this condition was maintained in the following operation. Under stirring for 2 minutes70.6g of a pre-emulsion of the first stage monomer (first portion) and 20.6g of sodium persulfate (SPS, 4.1% by weight in water) were added in parallel to the flask. Five minutes after the first portion was added, the remaining pre-emulsion of the first stage monomers was fed over 120 minutes. Then, the addition of the pre-emulsion of the second stage monomer was started and completed within 30 minutes. Separately, once the addition of the second portion of the first stage monomers was started, a feed of 72.7g of SPS (4.1% by weight in water) was started for 150 minutes. After 30 minutes of completion of the SPS feed, the reaction temperature was lowered to 75 ℃ and 6.5g of an ammonia solution (20% by weight aqueous solution) was added to neutralize the system. Then, 22.7g t-BHP (10 wt% aqueous solution) and 30.4g SAB (13 wt% aqueous solution) were added in parallel over 90 minutes. After the feeds of t-BHP and SAB were complete, the reaction mixture was cooled to 20 ℃ and neutralized with aqueous NaOH to pH 8. Finally, biocide (2.7 g) was added

MV and 8.7g

MBS, all from THOR, Germany) was added to the mixture.

The aqueous multistage polymer emulsion obtained had a pH of 8, a solids content of 49% by weight and a particle size of 166 nm.

Example 6 (control):

a pre-emulsion of the first stage mixture was prepared by the following procedure: 16.8g SR1025, 8.9gRS710, 5.1g PAM100, 34.2g acrylamide solution (Am, 30 wt% aqueous solution), 12.4g Acrylic Acid (AA), 32.2g Glycidyl Methacrylate (GMA), 735.1g Butyl Acrylate (BA), 154.1g Styrene (ST), and 524.6g deionized water were mixed in a vessel, and then emulsified by stirring at 500rpm for 10 minutes using a magnetic stir bar.

The pre-emulsion of the second stage mixture was prepared by the following procedure: 1.8g SR1025, 6.4gRS710, 5.2g Acrylic Acid (AA), 24.4g Glycidyl Methacrylate (GMA), 193.2g Butyl Acrylate (BA), 103.0g Styrene (ST), and 159.7g deionized water were mixed in a vessel and then emulsified by stirring at 500rpm for 10 minutes using a magnetic stir bar.

5.3g SR1025 and 405.9g water were charged to a four liter, multi-necked flask equipped with a mechanical stirring device under a nitrogen atmosphere. The mixture was heated to a temperature of 90 ℃ under a nitrogen atmosphere and, unless otherwise stated, this condition was maintained in the following operation. 72.2g of a pre-emulsion of the first stage monomer (first part) and 21.1g of sodium persulfate (SPS, 4.1% by weight in water) were added in parallel to the flask over 2 minutes with stirring. Five minutes after the first portion was added, the remaining pre-emulsion of the first stage monomers was fed over 120 minutes. After the feed of the first stage monomer was completed, the reaction was kept as it was for 30 minutes. Then, the addition of the pre-emulsion of the second stage monomer was started and completed within 30 minutes. Separately, once the addition of the second portion of the first stage monomers was started, a feed of 74.3g of SPS (4.1% by weight in water) was started. The SPS feed was first continued for 120 minutes, then paused for 30 minutes, and then continued for another 30 minutes. After 30 minutes of completion of the SPS feed, the reaction temperature was lowered to 55 ℃ and 39.9g of NaOH solution (8% by weight aqueous solution) was added to neutralize the system. Then, 23.2g t-BHP (10 wt% aqueous solution) and 45.9g FF6M (10 wt% aqueous solution) were added in parallel over 90 minutes. After the feed of t-BHP and FF6M was complete, the reaction mixture was cooled to 20 ℃ and neutralized with aqueous NaOH to pH 7. Finally, biocide (2.7 g) was added

MV and 8.7g

MBS, all from THOR, Germany) was added to the mixture.

The aqueous multistage polymer emulsion obtained had a pH of 7, a solids content of 48% by weight and a particle size of 155 nm.

Example 7 (control):

a pre-emulsion of the first stage mixture was prepared by the following procedure: 3.2g SR1025, 2.0gRS710, 8.8g acrylamide solution (Am, 30 wt% aqueous solution), 3.4g Acrylic Acid (AA), 26.4g Glycidyl Methacrylate (GMA), 62.5g Butyl Acrylate (BA), 150.2g Styrene (ST), and 157.9g deionized water were mixed in a vessel, and then emulsified with a magnetic stir bar for 10 minutes at 500 rpm.

The pre-emulsion of the second stage mixture was prepared by the following procedure: 17.6g SR1025, 10.5gRS710, 5.2g PAM100, 763.2g Butyl Acrylate (BA), 252.2g Styrene (ST), 35.3g acrylamide solution (Am, 30 wt% aqueous solution), 13.5g Acrylic Acid (AA), and 518.7g deionized water were mixed in a vessel, and then emulsified by stirring at 500rpm for 10 minutes using a magnetic stir bar.

5.25g SR1025 and 401.4g water were charged to a four-liter, multi-necked flask equipped with a mechanical stirring device under a nitrogen atmosphere. The mixture was heated to a temperature of 90 ℃ under a nitrogen atmosphere and, unless otherwise stated, this condition was maintained in the following operation. 79.5g of a pre-emulsion of the first stage monomer (first part) and 20.8g of sodium persulfate (SPS, 4.1% by weight in water) were added in parallel to the flask with stirring over 2 minutes. Five minutes after the first portion was added, the remaining pre-emulsion of the first stage monomers was fed over 120 minutes. Then, the pre-emulsion of the second stage monomer was added over 30 minutes. Separately, once the addition of the second portion of the first stage monomer was started, a feed of 73.5g of SPS (4.1 wt% aqueous solution) was started. The SPS feed was first continued for 120 minutes, then paused for 30 minutes, and then continued for another 30 minutes. 30 minutes after the completion of the SPS feed, the reaction temperature was lowered to 55 ℃ and 6.47g of an ammonia solution (20% by weight aqueous solution) and 10.4g of an NaOH solution (8% by weight aqueous solution) were added to neutralize the system. Then, 23.0g t-BHP (10 wt% aqueous solution) and 45.4g FF6M (10 wt% aqueous solution) were added in parallel over 90 minutes. After the feed of t-BHP and FF6M was complete, the reaction mixture was cooled to 20 ℃ and neutralized with aqueous NaOH to pH 8. Finally, biocide (2.7 g) was added

MV and 8.7g

MBS, all from THOR, Germany) was added to the mixture.

The aqueous multistage polymer emulsion obtained had a pH of 8, a solids content of 49% by weight and a particle size of 169 nm.

Example 8 (control):

a pre-emulsion of the first stage mixture was prepared by the following procedure: 12.9g SR1025, 11.6gRS710, 5.0g PAM100, 53.0g acrylamide solution (Am, 30 wt% aqueous solution), 15.1g Acrylic Acid (AA), 0.0014g Glycidyl Methacrylate (GMA), 587.2g Butyl Acrylate (BA), 231.5g Styrene (ST), and 524.6g deionized water were mixed in a vessel, and then emulsified by stirring at 500rpm for 10 minutes using a magnetic stir bar.

The pre-emulsion of the second stage mixture was prepared by the following procedure: 1.0g SR1025, 7.7gRS710, 0.7g Acrylic Acid (AA), 26.0g Glycidyl Methacrylate (GMA), 252.9g Butyl Acrylate (BA), 140.7g Styrene (ST), and 159.7g deionized water were mixed in a vessel and then emulsified by stirring at 500rpm for 10 minutes using a magnetic stir bar.

5.3g SR1025 and 405.9g water were charged to a four liter, multi-necked flask equipped with a mechanical stirring device under a nitrogen atmosphere. The mixture was heated to a temperature of 90 ℃ under a nitrogen atmosphere and, unless otherwise stated, this condition was maintained in the following operation. 72.2g of a pre-emulsion of the first stage monomer (first part) and 21.1g of sodium persulfate (SPS, 4.1% by weight in water) were added in parallel to the flask over 2 minutes with stirring. Five minutes after the first portion was added, the remaining pre-emulsion of the first stage monomers was fed over 120 minutes. After the feed of the first stage monomer was completed, the reaction was kept as it was for 30 minutes. Then, the addition of the pre-emulsion of the second stage monomer was started and completed within 30 minutes. Separately, once the addition of the second portion of the first stage monomers was started, a feed of 74.3g of SPS (4.1% by weight in water) was started. The SPS feed was first continued for 120 minutes, then paused for 30 minutes, and then continued for another 30 minutes. 30 minutes after the completion of the SPS feed, the reaction temperature was lowered to 55 ℃ and 39.9g of NaOH solution (8% by weight aqueous solution) was added to neutralize the productIs described. Then, 23.2g t-BHP (10 wt% aqueous solution) and 45.9g FF6M (10 wt% aqueous solution) were added in parallel over 90 minutes. After the feed of t-BHP and FF6M was complete, the reaction mixture was cooled to 20 ℃ and neutralized with aqueous NaOH to pH 8. Finally, biocide (2.7 g) was added

MV and 8.7g

MBS, all from THOR, Germany) was added to the mixture.

The aqueous multistage polymer emulsion obtained had a pH of 8, a solids content of 47% by weight and a particle size of 165 nm.

Example 9 (control):

the pre-emulsion mixture was prepared by the following procedure: 11.5g of DB45, 13.0g of Maphos24T, 5.2g of PAM100, 65.0g of an acrylamide solution (Am, 30 wt% aqueous solution), 16.9g of Acrylic Acid (AA), 25.5g of Glycidyl Methacrylate (GMA), 725.5g of butyl acrylate, 505.7g of Styrene (ST) and 678.3g of deionized water were mixed in a vessel, and then emulsified by stirring at 500rpm for 10 minutes using a magnetic stirring bar.

Under the protection of nitrogen atmosphere, 5.7g

LDBS23, 0.33g of copper sulfate solution (0.1% by weight in water), and 398g of deionized water were charged into a four-liter, multi-necked flask equipped with a mechanical stirring device. The mixture was heated to a temperature of 90 ℃ under a nitrogen atmosphere and, unless otherwise stated, this condition was maintained in the following operation. 66.5g of the pre-emulsion of the first stage monomer (first part) and 20.7g of sodium persulfate (SPS, 4.1% by weight in water) were added in parallel to the flask with stirring over 2 minutes. Five minutes after the first portion was added, the remaining pre-emulsion of the first stage monomers was fed over 90 minutes. Then, the pre-emulsion of the second stage monomer was added over 60 minutes. Separately, once the addition of the second portion of the first stage monomer was started, 72.9g SPS (4.1% by weight) was startedAqueous solution of (d) is fed). The SPS feed was first continued for 120 minutes, then paused for 30 minutes, and then continued for another 30 minutes. After 30 minutes of completion of the SPS feed, the reaction temperature was lowered to 75 ℃ and 6.5g of an ammonia solution (20% by weight aqueous solution) was added to neutralize the system. Then, 7.7g t-BHP (10 wt% aqueous solution) and 9.8g SAB (13 wt% aqueous solution) were added in parallel over 90 minutes. After the feeds of t-BHP and SAB were complete, the reaction mixture was cooled to 20 ℃ and neutralized with aqueous NaOH to pH 8. Finally, biocide (2.7 g) was added

MV and 8.7g

MBS, all from THOR, Germany) was added to the mixture.

The aqueous multistage polymer emulsion obtained had a pH of 8, a solids content of 49% by weight and a particle size of 144 nm.

Preparation and testing methods of coatings

A flask was first formulated with 130g deionized water, 6.5g Dispex AA 4140 (from BASF), 1.5g Dispex ultra FA4480 (from BASF), 2g Foamstar ST2410 AC (from BASF), 3g Natrosol250HBR (from Ashland), 2g Silres BS168 (from Wacker), 220g Lomon R996 (from Lomon), 110g Omyacarb 2 (from Omya), and 60g DB-80 (from Bright Industrial Co.). Then, 1g Kathon LX150 (from Dow), Acticide MBS (from Thor) with 81.5g deionized water was added followed by 324.32g of the polymer emulsion prepared above, 1.5g Foamstar ST2410 AC (from BASF), 1.5g of Dispex ultra FA4480 (from BASF), 5.8g of a solution of Rheovis HS 1212 (50% by weight in water from BASF), 1.67g of Rheovis PU1291 (50% by weight in water from BASF) and 46.71g deionized water. The pigment volume concentration of the resulting coating was 43%.

The DPUR and acid resistance tests were carried out according to the procedures and standards established in GB/T97802013. For testing of DPUR and acid resistance properties, step 6 has been followed. DPUR performance was evaluated using only the test score (R-value) for petrolatum black and a score of at least 6 points was considered acceptable. The acid resistance was evaluated using only the test score (R value) for vinegar, and at least 6 scores were considered acceptable.

The Low Temperature Film Flexibility (LTFF) test was performed as follows: each coating obtained in the above procedure was brushed on a putty plate of a4 size. And the coating was applied uniformly to the panels (i.e., the coating thickness was the same across the panel), each coated panel containing 40 grams of coating. The coated panels were then placed in a refrigerator at a temperature of 5 ℃ for 12 hours. Finally, the plates were inspected by visual inspection immediately after being removed from the refrigerator. If the panel did not show significant cracking, it would be rated "pass"; otherwise, it will be rated as "failed". For the present invention, a rating of "pass" is required.

The average particle diameter of the copolymer particles referred to herein is a Z average particle diameter measured by a Dynamic Light Scattering (DLS) method. The measurement method is described in the ISO 13321:1996 standard. For this purpose, a sample of the aqueous copolymer dispersion is diluted and the resulting aqueous dilution is analyzed. In the case of DLS, the water dilution may have a polymer concentration in the range of 0.001 wt% to 0.5 wt%, depending on the particle size. For most purposes, a suitable concentration is 0.01% by weight. However, higher or lower concentrations may be used to obtain the best signal-to-noise ratio. To avoid flocculation, dilution can be achieved by adding the aqueous copolymer dispersion to water or an aqueous solution of a surfactant. Typically, dilution is carried out by using as diluent a 0.1% by weight aqueous solution of a non-ionic emulsifier, for example an ethoxylated C16/C18 alkanol (degree of ethoxylation of 18).

Measurement configuration: high Performance Particle Sizers (HPPS), from Malvern Instruments, UK, automated, with continuous flow cell and Gilson autosampler.

Parameters are as follows: the measurement temperature is 20.0 ℃; measurement time 120 seconds (6 cycles, 20s each); scattering angle 173; laser wavelength 633nm (HeNe); refractive index of medium 1.332 (aqueous); the viscosity was 0.9546 mPas.

The measurements give the mean (fitted mean) of the second order cumulant analysis, i.e. the Z-mean. The "fitted average" is the average, intensity weighted hydrodynamic particle size in nm.

The results for DPUR, acid resistance and Low Temperature Film Flexibility (LTFF) are listed in table 1.

Examples 1-5 are working examples showing that polymer emulsions with appropriately controlled total Fox Tg (Tg0), Δ Tg, and weight ratio of first stage polymer to second stage polymer show better performance. In contrast, examples 6 to 9 were regarded as failed examples because at least one requirement was not satisfied.

TABLE 1

However, the present invention is not to be limited in scope by the specific embodiments and examples described herein. Indeed, various modifications of the invention in addition to those described herein will become apparent to those skilled in the art from the foregoing description. Such modifications are intended to fall within the scope of the appended claims.

Claims

1. An aqueous multistage polymer emulsion wherein the total calculated Fox Tg (Tg0) of the polymer is in the range of-15 ℃ to +5 ℃, the difference (Δ Tg) between the calculated Fox Tg (Tg2) of the second stage and the Fox Tg (Tg1) of the first stage is more than 10 ℃, and the weight ratio of the first stage polymer to the second stage polymer is in the range of 95:5 to 30:70 based on the total amount of monomers used for polymerization in each stage.

2. The aqueous multistage polymer emulsion of claim 1 wherein the monomers used in the first and second stages each independently comprise:

(A) at least one hydrophobic monoethylenically unsaturated monomer (a), the total amount of hydrophobic monoethylenically unsaturated monomers may be at least 80 wt.%, preferably at least 85 wt.%, more preferably at least 90 wt.%, most preferably at least 95 wt.%;

(B) at least one hydrophilic monoethylenically unsaturated monomer (b), the total amount of hydrophilic monoethylenically unsaturated monomers may be at least 0.1% by weight and not more than 20% by weight, preferably not more than 15% by weight, more preferably not more than 10% by weight, most preferably not more than 5% by weight.

3. The aqueous multistage polymer emulsion according to claim 2 wherein the monomers used in the first stage and/or the second stage further comprise one or more crosslinking monomers (c).

4. The aqueous multistage polymer emulsion according to any of claims 1 to 3 wherein the total calculated Fox Tg (Tg0) is in the range of-10 ℃ to +5 ℃, more preferably in the range of-10 ℃ to 0 ℃.

5. The aqueous multistage polymer emulsion according to any of claims 1 to 4 wherein the difference (Δ Tg) between the calculated Fox Tg of the second stage (Tg2) and the Fox Tg of the first stage (Tg1) exceeds 15 ℃.

6. The aqueous multistage polymer emulsion according to any of claims 1 to 5 wherein the weight ratio of first stage polymer to second stage polymer is in the range of 95:5 to 40:60, preferably in the range of 90:10 to 40:60, more preferably in the range of 90:10 to 50: 50.

7. The aqueous multistage polymer emulsion according to any of claims 1 to 6 wherein the particle size of the emulsion is in the range of 50-300nm, preferably in the range of 50-250nm, most preferably in the range of 50-200 nm.

8. A method of preparing a multistage polymer emulsion according to any of the preceding claims comprising:

step 1: polymerizing the first stage polymer;

step 2: the second stage polymer is then polymerized.

9. A coating comprising any one of the multistage polymer emulsions of any one of the preceding claims.