Polymer latex and an elastomeric film having self-healing properties made therefrom

Abstract

The present invention relates to an aqueous dispersion comprising core-shell polymer latex particles, wherein the shell of the core-shell polymer latex particles bears ethylenically unsaturated groups pendant from the polymer backbone of the latex particle shell, wherein the ethylenically unsaturated moiety is separated from the polymer backbone by at least three chemical bonds, and wherein the shell of the core-shell particles is crosslinked and the core of the core-shell particles is not crosslinked, to a method of manufacturing the aqueous dispersion, to an elastomeric film made from the aqueous dispersion, to an article comprising the elastomeric film and to a method of manufacturing a self-supporting elastomeric film from the aqueous dispersion.

Description

[0001] The present invention relates in particular, but not exclusively, to an aqueous dispersion comprising core-shell polymer latex particles particularly suitable for the preparation of elastomeric membranes, a method for manufacturing such an aqueous dispersion, an elastomeric membrane made from said aqueous dispersion, and a method for manufacturing a self-supporting elastomeric membrane using said aqueous dispersion. Background of the Invention

[0003] According to current industrial standards, elastomeric membranes, particularly in dip molding applications such as surgical gloves, are manufactured from blends containing carboxylated nitrile latex (XNBR). In order to obtain the mechanical strength required for the use of these elastomeric membranes, some crosslinking of the membrane needs to be achieved during the manufacture of the elastomeric membrane.

[0004] In the prior art, several different concepts can be utilized to obtain such crosslinked elastomeric membranes. One possibility is that the blend for manufacturing the elastomeric membrane contains a conventional sulfur vulcanization system, for example, a combination of sulfur with accelerators such as thiuram and carbamate and zinc oxide.

[0005] Since sulfur vulcanization systems may cause allergic reactions, alternative concepts for curing latex membranes have been developed. Another possibility is to include a crosslinking agent component such as a polyvalent cation, for example, zinc oxide or other polyfunctional organic compounds, in the blend, which are suitable for reacting with functional groups on the latex particles to achieve chemical crosslinking. In addition, if the polymer latex carries a sufficient amount of self-crosslinking groups such as N-hydroxymethylamide groups, the sulfur vulcanization system and / or crosslinking agent can be completely avoided.

[0006] Systems using specific additives such as sulfur or crosslinking agents are summarized in WO2018 / 111087 and WO2017 / 164726.

[0007] WO2017 / 209596 discloses a polymer latex for dip molding applications, which comprises two different types of latex particles. One type of latex particle is carboxylated, while the second type of latex particle contains ethylene oxide functional groups.

[0008] All these different concepts result in crosslinked elastomeric membranes, where the crosslinking is essentially irreversible, such that these elastomeric membranes can neither be easily regenerated, nor do they exhibit any self-healing properties. For example, if any type of defect such as a pinhole occurs during the manufacture of the elastomeric membrane, due to the lack of self-healing properties of the membrane, these products need to be scrapped, which generates non-reusable waste. Additionally, if such an elastomeric membrane breaks during its use, it cannot be repaired, resulting in irreversible damage to the elastomeric membrane and thus the failure of the article containing such an elastomeric membrane.

[0009] Accordingly, there is a desire in the industry for such elastomeric membranes that have inherent self-healing properties and can potentially be regenerated in order to reduce the non-usable waste of such elastomeric membranes and avoid the ultimate failure of articles containing such elastomeric membranes. This would also lead to a more environmentally friendly technology for manufacturing elastomeric membranes. In addition, such a system would avoid the need for using materials that can cause the so-called type IV allergic reactions.

[0010] US4244850, JPS6069178, and US5306744 disclose polymer latex compositions to be used in coating compositions or adhesives, which comprise: polymer latex particles having ethylenically unsaturated groups, and the ethylenically unsaturated groups can be introduced by reacting with ethylenically unsaturated compounds having functional groups reactive with the functional groups present on the latex particles through the functional groups present on the latex particles. Although US5306744 and JPS6069178 disclose core-shell particles obtained by two-step emulsion polymerization, the core in these particles is crosslinked, and the shell is not crosslinked. None of these references relate to elastomeric membranes, nor do they relate to the self-healing properties of elastomeric membranes.

[0011] Accordingly, the present invention seeks to provide a polymer latex composition suitable for preparing an elastomeric membrane having self-healing properties. Summary of the Invention

[0013] According to a first aspect of the present invention, there is provided an aqueous dispersion comprising core-shell polymer latex particles, wherein the shell of the core-shell polymer latex particles bears ethylenically unsaturated groups pendant from the polymer backbone of the latex particle shell, wherein the ethylenically unsaturated moiety is separated from the polymer backbone by at least 3 chemical bonds, and wherein the shell of the core-shell particles is crosslinked and the core of the core-shell particles is not crosslinked.

[0014] Furthermore, according to another aspect, the present invention also relates to a method for manufacturing an aqueous dispersion comprising core-shell polymer latex particles by aqueous emulsion polymerization including at least two steps, wherein the shell of the core-shell polymer latex particles bears ethylenically unsaturated groups pendant from the polymer backbone of the latex particle shell, wherein the shell of the core-shell particles is crosslinked and the core of the core-shell particles is not crosslinked, wherein

[0015] I) in the step of manufacturing the core of the core-shell particles, polymerize ethylenically unsaturated monomers that do not contain monomers having more than one non-conjugated ethylenically unsaturated group; and

[0016] II) in the step of manufacturing the shell, polymerize a monomer mixture comprising the following:

[0017] a) a monomer selected from conjugated dienes, monoethylenically unsaturated monomers that do not have a functional group capable of subsequently reacting after the formation of the latex particles to introduce an ethylenically unsaturated group, and combinations thereof; and

[0018] b) i) a monomer having at least two non-conjugated ethylenically unsaturated groups that exhibit different reactivities in the aqueous emulsion polymerization, wherein at least a portion of the ethylenically unsaturated groups having a lower reactivity remain unreacted after the termination of the aqueous emulsion polymerization; and / or

[0019] ii) a monoethylenically unsaturated monomer having a functional group capable of subsequently reacting after the formation of the latex particles to introduce an ethylenically unsaturated group; and

[0020] c) a monomer different from b i) having at least two non-conjugated ethylenically unsaturated groups, wherein:

[0021] if there is no monomer b i), at least a portion of the functional groups of monomer b ii) react after the termination of the aqueous emulsion polymerization to introduce an ethylenically unsaturated group.

[0022] Additionally, according to a further aspect, the present invention relates to an elastomeric film made from the aqueous dispersion of the present invention, wherein the film is preferably self-supporting and substantially free of sulfur crosslinking and substantially free of ionomer crosslinking.

[0023] Another aspect of the present invention relates to a method for manufacturing a self-supporting elastomeric film, comprising:

[0024] a) providing a composition comprising the aqueous dispersion defined above,

[0025] b) applying the composition onto a substrate to form a wet film,

[0026] c) drying and / or curing the wet film to form an elastomeric film, and

[0027] d) separating the elastomeric film from the substrate,

[0028] e) optionally, before or after step d), heat-treating the elastomeric film at a temperature of 20 °C - 160 °C, preferably 25 °C - 100 °C, more preferably 75 °C - 100 °C.

[0029] Furthermore, in another aspect, the present invention also relates to an article comprising the elastomeric film according to the present invention.

[0030] Additionally, the inventors have surprisingly found that the elastomeric film obtained from the aqueous dispersion of the present invention exhibits shape retention properties when the elastomeric film is subjected to moderate temperatures, in addition to self-healing properties, as shown in more detail in the examples. Description of the Drawings

[0031] Figure 1 Shows the d of the nanoparticles of the examples measured by dynamic light scattering as a function of pH z value.

[0032] Figure 2a Shows (a) before cutting, (b) the dumbbell cut into two pieces and the upper surface of the dumbbell marked, (c) reconnected by pressing for 60 seconds, and (d) after annealing at 40 °C for 24 hours, according to Examples 3 and 11.

[0033] Figure 2b Shows the stress-strain data of the original and cut-and-recombined dumbbell films according to Examples 3, 8, 11, and 13.

[0034] Figure 3 Shows the shape memory performance of the films according to Examples 3 and 11.

[0035] Figure 4 Shows the relaxation of the folded and spring-like film samples according to Examples 3 and 11.

[0036] Detailed Description

[0037] The present invention will be described in more detail below.

[0038] Shows an aqueous dispersion comprising core-shell latex particles, wherein the shell of the core-shell particles is crosslinked and the core of the core-shell particles is not crosslinked. In particular, the core-shell polymer latex particles carry ethylenically unsaturated groups pendant from the polymer backbone of the latex particle shell, wherein the ethylenically unsaturated moiety is separated from the polymer backbone by at least 3 chemical bonds.

[0039] Thus, the polymer latex particles are clearly distinguishable from core-shell particles in which the crosslinked shell is formed by polymerizing a monomer mixture containing a conjugated diene such as butadiene, because the remaining double bond formed by the polymerization of one double bond of the conjugated diene during free radical emulsion polymerization will be separated from the polymer backbone of the shell by less than three chemical bonds.

[0040] In particular, the shell of the core-shell polymer particles may comprise a structural unit represented by formula (1):

[0041] - L - CR 1 =CR 2 R 3 (1)

[0042] wherein L is between the polymer backbone of the latex particle shell and -CR 1 =CR 2 R 3A linear or branched divalent group providing at least two atoms in the chain between, or a divalent group containing a cyclic group, and R 1 、R 2 and R 3 are independently selected from hydrogen and monovalent organic groups, preferably C 1 -C 4 alkyl groups.

[0043] In formula (1), -L- can be selected from divalent hydrocarbon groups and groups containing at least one heteroatom in the chain connecting -CR 1 =CR 2 R 3 to the polymer backbone. Preferably, -L- contains groups selected from the following in the chain connecting -CR 1 =CR 2 R 3 to the polymer backbone: ester, ether, carbamate, thiocarbamate, urea, amide groups and combinations thereof.

[0044] Thus, there are generally two different synthetic routes by which polymer latex particles can be produced. According to one route, the monomer mixture for the shell portion of the core-shell particles for polymerization contains, in addition to monomers having at least two non-conjugated ethylenically unsaturated groups that cause crosslinking of the shell portion of the polymer latex particles, monomers having at least two non-conjugated ethylenically unsaturated groups that exhibit different reactivities in the aqueous emulsion polymerization, whereby at least a portion of these ethylenically unsaturated groups having lower reactivity remain unreacted after termination of the aqueous emulsion polymerization. Thus, ethylenically unsaturated groups having the required spacing from the polymer backbone of the shell polymer remain present on the surface of the polymer latex particles according to the present invention.

[0045] Alternatively, the polymer latex particles can be prepared by polymerizing a monomer mixture for the shell portion of the core-shell particles containing monoethylenically unsaturated monomers having such functional groups that can react subsequently after the formation of the latex particles to introduce ethylenically unsaturated groups, and then reacting the functional groups after termination of the aqueous emulsion polymerization to introduce ethylenically unsaturated groups.

[0046] Thus, the core-shell latex particles can be manufactured by an aqueous emulsion polymerization comprising at least two steps, wherein:

[0047] I) In the step of manufacturing the core of the core-shell particles, polymerize ethylenically unsaturated monomers that do not contain monomers having more than one non-conjugated ethylenically unsaturated group; and

[0048] II) In the step of manufacturing the shell, polymerize a monomer mixture comprising:

[0049] a) monomers selected from conjugated dienes, monoethylenically unsaturated monomers that do not have functional groups capable of subsequently reacting after latex particle formation to introduce ethylenically unsaturated groups, and combinations thereof; and

[0050] b) i) monomers having at least two non-conjugated ethylenically unsaturated groups that exhibit different reactivities in aqueous emulsion polymerization, wherein at least a portion of the ethylenically unsaturated groups having lower reactivity remain unreacted after termination of the aqueous emulsion polymerization; and / or

[0051] ii) monoethylenically unsaturated monomers having functional groups capable of subsequently reacting after latex particle formation to introduce ethylenically unsaturated groups; and

[0052] c) monomers different from b i) having at least two non-conjugated ethylenically unsaturated groups, wherein:

[0053] if there are no monomers b i), then at least a portion of the functional groups of monomers b ii) react after termination of the aqueous emulsion polymerization to introduce ethylenically unsaturated groups.

[0054] Monomer a)

[0055] The monomers a) for polymerizing the shell portion of the core-shell particles of the present invention can suitably be selected from conjugated dienes, aromatic vinyl compounds, linear alkyl esters of ethylenically unsaturated acids, branched alkyl esters of ethylenically unsaturated acids, linear alkylamides of ethylenically unsaturated acids, branched alkylamides of ethylenically unsaturated acids, ethylenically unsaturated nitriles, vinyl esters of carboxylic acids, diesters of ethylenically unsaturated acids, vinyl ethers, ethylenically unsaturated silanes, olefins, and any combination thereof.

[0056] Suitable conjugated dienes may be selected from 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-octatriene, 2-methyl-6-methylene-1,7-octadiene, 7-methyl-3-methylene-1,6-octadiene, 1,3,7-octatriene, 2-ethyl-1,3-butadiene, 2-pentyl-1,3-butadiene, 3,7-dimethyl-1,3,7-octatriene, 3,7-dimethyl-1,3,6-octatriene, 3,7,11-trimethyl-1,3,6,10-dodecatetraene, 7,11-dimethyl-3-methylene-1,6,10-dodecatriene, 2,6-dimethyl-2,4,6-octatriene, 2-phenyl-1,3-butadiene, 2-methyl-3-isopropyl-1,3-butadiene, and 1,3-cyclohexadiene. 1,3-Butadiene, isoprene, and combinations thereof are preferred conjugated dienes. 1,3-Butadiene is particularly preferred.

[0057] 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 vinyldimethylbenzene, 2-vinylpyridine, 4-vinylpyridine, 1,1-diphenylethylene, and substituted 1,1-diphenylethylene, 1,2-diphenylethylene, and substituted 1,2-diphenylethylene. Mixtures of one or more vinyl aromatic compounds may also be used. Preferred monomers are styrene and α-methylstyrene.

[0058] The alkyl esters of ethylenically unsaturated acids may be selected from the n-alkyl esters, isoalkyl esters, or tert-alkyl esters of (meth)acrylic acid, wherein the alkyl group has 1 to 20 carbon atoms, the reaction product of (meth)acrylic acid with the glycidyl ester of a neo-carboxylic acid (preferably a tert-carbonic acid, neodecanoic acid, or pivalic acid), and (meth)acrylic acid alkoxyalkyl ester monomers.

[0059] Generally, preferred (meth)acrylic acid alkyl esters may be selected from (meth)acrylic acid C 1 -C 20 alkyl esters, preferably (meth)acrylic acid C 1 -C 10 alkyl esters. Examples of such acrylate monomers include n-butyl acrylate, sec-butyl acrylate, methyl 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 cetyl methacrylate. Particularly preferably selected from the following (meth)acrylates: methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and combinations thereof.

[0060] (Meth)acrylic acid alkoxyalkyl ester monomers that can be used as monomer (a) include methoxyethyl methacrylate, ethoxyethyl methacrylate, methoxybutyl methacrylate, ethoxyethyl acrylate, butoxyethyl methacrylate, methoxybutyl acrylate, and methoxyethoxyethyl acrylate. Preferred (meth)acrylic acid alkoxyalkyl ester monomers are ethoxyethyl acrylate and methoxyethyl acrylate.

[0061] Amides of ethylenically unsaturated acids may be selected from (meth)acrylamide, N-hydroxymethyl (meth)acrylamide, and diacetone acrylamide. The preferred amide monomer is (meth)acrylamide.

[0062] Examples of ethylenically unsaturated nitrile monomers of monomer (a) that can be used to prepare the shell of the core-shell latex particles according to the present invention include polymerizable unsaturated aliphatic nitrile monomers containing 2-4 carbon atoms in a linear or branched arrangement, which may be substituted with an acetyl group or another nitrile group. Such nitrile monomers include acrylonitrile, methacrylonitrile, α-cyanoethyl acrylonitrile, fumaric acid nitrile, and combinations thereof, and acrylonitrile is most preferred.

[0063] Suitable vinyl esters of ethylenically unsaturated acids may be selected from vinyl acetate, vinyl propionate, vinyl butyrate, vinyl benzoate, vinyl 2-ethylhexanoate, vinyl stearate, and vinyl versatate. The most preferred vinyl ester is vinyl acetate.

[0064] Suitable diesters of ethylenically unsaturated acids may be selected from dimethyl maleate, diethyl maleate, dipropyl maleate, dibutyl maleate, dihexyl maleate, bis(2-ethylhexyl) maleate, dioctyl maleate, bis(6-methylheptyl) maleate, dimethyl fumarate, diethyl fumarate, dipropyl fumarate, dibutyl fumarate, dihexyl fumarate, bis(2-ethylhexyl) fumarate, dioctyl fumarate, bis(6-methylheptyl) fumarate. The most preferred diester is dibutyl maleate.

[0065] The ethylenically unsaturated silanes may be selected from trialkoxyvinyl esters such as trimethoxyvinylsilane, triethoxyvinylsilane; (meth)acrylic acid trialkoxy esters such as trimethylsilyl (meth)acrylate and triethylsilyl (meth)acrylate, 3-(trimethoxysilyl)propyl (meth)acrylate and 3-(trimethoxysilyl)propyl (meth)acrylate, 3-methacryloylaminopropyltriethoxysilane and combinations thereof; and / or the vinyl ethers are selected from alkyl vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, 2-ethylhexyl vinyl ether, dodecyl vinyl ether, octadecyl vinyl ether and cyclohexyl vinyl ether.

[0066] Monomer bi)

[0067] Suitable monomers bi) are selected from allyl (meth)acrylate, allyl crotonate, N,N-diallyl (meth)acrylamide, 2-allyloxyethyl (meth)acrylate, 2-allyloxyethoxyethyl (meth)acrylate, vinyl oxybutyl (meth)acrylate and butenyl (meth)acrylate.

[0068] Monomer bii)

[0069] Suitable monomers bii) for preparing the shell of the core-shell particles according to the present invention may be selected from carboxylic acid-functional ethylenically unsaturated monomers, ethylene oxide-functional ethylenically unsaturated monomers, hydroxyl-functional ethylenically unsaturated monomers, isocyanate-functional monomers and amino-functional ethylenically unsaturated monomers.

[0070] The ethylenically unsaturated carboxylic acid monomers suitable as monomer (bii) according to the present invention include monocarboxylic and dicarboxylic acid monomers and monoesters of dicarboxylic acids. For carrying out the present invention, it is preferred to use ethylenically unsaturated aliphatic monocarboxylic or dicarboxylic acids or acid anhydrides having 3 to 5 carbon atoms. Examples of monocarboxylic acid monomers include acrylic acid, acrylic anhydride, methacrylic acid, 4-vinylbenzoic acid, trichloroacrylic acid, crotonic acid, 2-carboxyethyl acrylate, and monoesters of maleic acid or fumaric acid such as monomethyl maleate, monoethyl maleate, monobutyl maleate, monohexyl maleate, mono(2-ethylhexyl) maleate, monolauryl maleate, monomethyl fumarate, monoethyl fumarate, monobutyl fumarate, monohexyl fumarate, mono(2-ethylhexyl) fumarate, monolauryl fumarate; and examples of dicarboxylic acid monomers include fumaric acid, itaconic acid, 4-methacryloyloxyethyl trimellitic anhydride, maleic acid, and maleic anhydride. Examples of other suitable ethylenically unsaturated acids include vinylacetic acid, vinyllactic acid, vinylsulfonic acid, 2-methyl-2-propene-1-sulfonic acid, styrenesulfonic acid, acrylaminomethylpropanesulfonic acid and its salts. Preferably, the ethylenically unsaturated carboxylic acid monomer is selected from (meth)acrylic acid, crotonic acid, 2-carboxyethyl acrylate, itaconic acid, maleic acid, fumaric acid and combinations thereof.

[0071] Suitable ethylene oxide-functional ethylenically unsaturated monomers may be selected from glycidyl (meth)acrylate, allyl glycidyl ether, vinyl glycidyl ether, vinylcyclohexene oxide, limonene oxide, 2-ethylglycidyl acrylate, 2-ethylglycidyl methacrylate, 2-(n-propyl)glycidyl acrylate, 2-(n-propyl)glycidyl methacrylate, 2-(n-butyl)glycidyl acrylate, 2-(n-butyl)glycidyl methacrylate, dimethylglycidyl methacrylate, glycidylmethyl methacrylate, glycidyl acrylate, 2,3-epoxybutyl methacrylate, 2-ethyl(3',4'-epoxyheptyl) acrylate, 2-ethyl(3',4'-epoxyheptyl) methacrylate, (6',7'-epoxyheptyl) acrylate, (6',7'-epoxyheptyl) methacrylate, allyl-3,4-epoxyheptyl ether, 6,7-epoxyheptyl allyl ether, vinyl-3,4-epoxyheptyl ether, 3,4-epoxyheptyl vinyl ether, 6,7-epoxyheptyl vinyl ether, o-vinylbenzyl glycidyl ether, m-vinylbenzyl glycidyl ether, p-vinylbenzyl glycidyl ether, 3-vinylcyclohexene oxide, α-methylglycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, (3-methyloxirane-2-yl)methyl 2-methylacrylate, styrene glycidyl ether, 2,4-vinylphenyl glycidyl ether and combinations thereof. Glycidyl (meth)acrylate is particularly preferred.

[0072] The (meth)acrylic acid hydroxyalkyl ester monomers include acrylic acid hydroxyalkyl esters and methacrylic acid hydroxyalkyl ester monomers, which are based on ethylene oxide, propylene oxide, and higher epoxides or mixtures thereof. Examples are 2-hydroxyethyl acrylate, 3-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, and 4-hydroxybutyl acrylate, glycerol monomethacrylate, N-hydroxyethylacrylamide, N-(2-hydroxypropyl)methacrylamide, 3-phenoxy-2-hydroxypropyl methacrylate, hydroxy polyethoxy(10)allyl ether, poly(ethylene glycol)-derived or poly(propylene glycol)-derived (meth)acrylates such as poly(propylene glycol) monomethacrylate containing an average of 6 propylene glycol units. Preferably, the (meth)acrylic acid hydroxyalkyl ester monomer is selected from 2-hydroxyethyl (meth)acrylate. Additionally or alternatively, the hydroxy monomer may include (meth)acrylic acid phenol ester, dopamine methacrylamide, or 4-vinylphenol.

[0073] Examples of the isocyanate monomer are 2-(acryloyloxy)ethyl isocyanate and 2-(methacryloyloxy)ethyl isocyanate.

[0074] The amino-functional ethylenically unsaturated compounds may be selected from 2-aminoethyl (meth)acrylate, aminopropyl (meth)acrylate, and aminobutyl (meth)acrylate, N-(2-aminoethyl)methacrylamide, N-(3-aminopropyl)methacrylamide, or salts thereof.

[0075] Monomer c)

[0076] Suitable monomers c) for crosslinking the shell of the core-shell latex particles of the present invention may be selected from monomers containing two ethylenically unsaturated groups, preferably selected from divinylbenzene, (meth)acrylates of polyols, allyl ethers of polycarboxylic acids, monomers containing three ethylenically unsaturated groups, preferably selected from diallyl maleate or trimethylolpropane tri(meth)acrylate, monomers containing four ethylenically unsaturated groups, preferably selected from pentaerythritol tetra(meth)acrylate, and any combination thereof. Examples of (meth)acrylates of polyols are ethylene glycol di(meth)acrylate, hexanediol di(meth)acrylate, tripropylene glycol di(meth)acrylate, butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, and dipropylene glycol di(meth)acrylate. Further examples of suitable monomers are those described in EP3119815. Monomers having at least two ethylenically unsaturated groups are preferably selected from divinylbenzene, 1,2-ethylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, and 1,6-hexanediol di(meth)acrylate.

[0077] According to the present invention, it is preferred that the shell of the core-shell particles is prepared by aqueous emulsion polymerization of a mixture of ethylenically unsaturated monomers comprising monomer a), monomer bii) and monomer c) and optionally monomer bi), thereby forming polymer latex particles having a shell with a first functional group bearing a functional group derived from monomer bii); and subsequently reacting the polymer latex particles bearing said first functional group with an ethylenically unsaturated compound which, in addition to an ethylenically unsaturated moiety, has a second functional group reactive with said first functional group.

[0078] Thus, according to the present invention, monomer bii) may be present and comprise an ethylenically unsaturated carboxylic acid, with the result that the first functional group is a carboxyl group and the ethylenically unsaturated compound having a second functional group to be reacted with the polymer latex particles is selected from epoxy-functional ethylenically unsaturated compounds. These epoxy-functional ethylenically unsaturated compounds may be selected from the epoxides as defined above as monomer bii) for use in preparing the shell of the core-shell particles.

[0079] Alternatively, monomer bii) may comprise an epoxy-functional ethylenically unsaturated compound as defined above, and said first functional group is an epoxy group and the ethylenically unsaturated compound having a second functional group is selected from ethylenically unsaturated carboxylic acids. These ethylenically unsaturated carboxylic acids may be selected from those carboxylic acid-functional monomers as defined above for use in making the shell of the core-shell particles.

[0080] Alternatively, monomer bii) may comprise a hydroxy-functional and / or amino-functional ethylenically unsaturated compound which may be selected from the monomers defined above, which gives a first functional group selected from hydroxy and amino, and the ethylenically unsaturated compound having a second functional group to be reacted with the polymer latex particles is selected from carboxylic acids, isocyanate-functional or thiocyanate-functional ethylenically unsaturated compounds.

[0081] Suitable carboxylic acids are those listed above; and suitable isocyanate-functional or thiocyanate-functional ethylenically unsaturated compounds may be selected from allyl isocyanate, 2-isocyanatoethyl (meth)acrylate, 3-isopropenyl-α,α'-dimethylbenzyl isocyanate, 2-isocyanatoethyl methacrylate, allyl isothiocyanate, 4-vinylbenzyl isothiocyanate.

[0082] According to the present invention, it is preferred that only monomer bii) and no monomer bi) are used for making the shell of the core-shell particles. Particularly preferably, monomer bii) comprises an ethylenically unsaturated carboxylic acid and the ethylenically unsaturated compound having a second functional group to be reacted with the polymer latex particles is selected from epoxy-functional ethylenically unsaturated compounds, preferably as defined above.

[0083] The relative amounts of the monomers for the shell of the core-shell particles of the present invention are not particularly critical, provided that the amounts of monomers b) and c) as defined above for their preferred embodiments are sufficient to provide a crosslinked shell and an ethylenically unsaturated moiety of the shell, either by initially using monomer bi) or by subsequent reaction with a functional ethylenically unsaturated compound if monomer bii) is present. Thus, the monomer mixture for the shell of the core-shell particles of the present invention may comprise 78-99.8 wt% of monomer a); preferably, the monomer composition for the shell of the core-shell particles may comprise 78-99 wt% of monomer a), 0.5-16 wt% of monomer b) and 0.5-6 wt% of monomer c), more preferably 80-98 wt% of monomer a), 1-15 wt% of monomer b) and 0.1-5 wt% of monomer c), even more preferably 85-98 wt% of monomer a), 1-10 wt% of monomer b) and 1-5 wt% of monomer c), even more preferably 88-96 wt% of monomer a), 3-8 wt% of monomer b) and 0.1-4 wt% of monomer c), and most preferably 90-97 wt% of monomer a), 2-7 wt% of monomer b), 0.5-3 wt% of monomer c).

[0084] The monomers a) which typically constitute the major monomers in the monomer mixture for the shell of the core-shell particles according to the present invention and their relative amounts are selected to adjust the desired properties of the polymer latex composition and the elastomeric film prepared therefrom.

[0085] Thus, monomer a) may comprise:

[0086] - 15-99 wt% of an alkyl (meth)acrylate, including an alkoxyalkyl (meth)acrylate;

[0087] - 1-80 wt% of an ethylenically unsaturated nitrile compound,

[0088] - 0-50 wt% of a vinyl aromatic monomer,

[0089] - 0-90 wt% of a conjugated diene,

[0090] - 0-18 wt% of a vinyl carboxylate and / or vinyl ether,

[0091] - 0-10 wt% of an ethylenically unsaturated compound with a silane, and

[0092] - 0-18 wt% of an ethylenically unsaturated compound with an amide group,

[0093] wherein the weight percentages are based on the total weight of monomer a).

[0094] According to the present invention, the monomer amount of monomer a) of the monomer mixture for preparing the shell of the core-shell particles of the present invention defined above can add up to 100 wt%.

[0095] Typically, the amount of (meth)acrylate monomers including alkoxyalkyl (meth)acrylates is 15 - 99 wt%, preferably 20 - 90 wt%, more preferably 40 - 80 wt%, most preferably 50 - 75 wt%, based on the total weight of the monomers. Accordingly, the amount of conjugated diene present can be at least 15 wt%, at least 20 wt%, at least 22 wt%, at least 24 wt%, at least 26 wt%, at least 28 wt%, at least 30 wt%, at least 32 wt%, at least 34 wt%, at least 36 wt%, at least 38 wt% or at least 40 wt%, based on the total weight of the ethylenically unsaturated monomer (a).

[0096] Accordingly, the amount of (meth)acrylate monomers including alkoxyalkyl (meth)acrylates used can be not more than 95 wt%, not more than 90 wt%, not more than 85 wt%, not more than 80 wt%, not more than 78 wt%, not more than 76 wt%, not more than 74 wt%, not more than 72 wt%, not more than 70 wt%, not more than 68 wt%, not more than 66 wt%, not more than 64 wt%, not more than 62 wt%, not more than 60 wt%, not more than 58 wt% or not more than 56 wt%. Those skilled in the art will understand any range between any explicitly disclosed lower and upper limits disclosed herein.

[0097] The nitrile monomer can be included in an amount of 1 - 80 wt%, preferably 10 - 70 wt% or 1 - 60 wt% and more preferably 15 - 50 wt%, even more preferably 20 - 50 wt%, most preferably 20 - 40 wt%, based on the total weight of the ethylenically unsaturated monomer (a).

[0098] Accordingly, the amount of unsaturated nitrile present can be at least 1 wt%, at least 5 wt%, at least 10 wt%, at least 12 wt%, at least 14 wt%, at least 16 wt%, at least 18 wt%, at least 20 wt%, at least 22 wt%, at least 24 wt%, at least 26 wt%, at least 28 wt%, at least 30 wt%, at least 32 wt%, at least 34 wt%, at least 36 wt%, at least 38 wt% or at least 40 wt%, based on the total weight of the ethylenically unsaturated monomer (a).

[0099] Therefore, the amount of the unsaturated nitrile monomer used may be no more than 80 wt%, no more than 75 wt%, no more than 73 wt%, no more than 70 wt%, no more than 68 wt%, no more than 66 wt%, no more than 64 wt%, no more than 62 wt%, no more than 60 wt%, no more than 58 wt%, no more than 56 wt%, no more than 54 wt%, no more than 52 wt%, no more than 50 wt%, no more than 48 wt%, no more than 46 wt% or no more than 44 wt%. Those skilled in the art will understand that any range between any explicitly disclosed lower and upper limits is disclosed herein.

[0100] The amount of the vinyl aromatic compound used may be 0 - 50 wt%, preferably 0 - 40 wt%, more preferably 0 - 25 wt%, even more preferably 0 - 15 wt% and most preferably 0 - 10 wt%, based on the total weight of the ethylenically unsaturated monomer (a). Therefore, the amount of the vinyl aromatic compound present may be no more than 35 wt%, no more than 30 wt%, no more than 25 wt%, no more than 20 wt%, no more than 18 wt%, no more than 16 wt%, no more than 14 wt%, no more than 12 wt%, no more than 10 wt%, no more than 8 wt%, no more than 6 wt%, no more than 4 wt%, no more than 2 wt% or no more than 1 wt%, based on the total weight of the ethylenically unsaturated monomer (a). The vinyl aromatic compound may also be completely absent.

[0101] Typically, the amount of the conjugated diene monomer present may be no more than 90 wt%, no more than 85 wt%, no more than 80 wt%, no more than 70 wt%, no more than 60 wt%, no more than 50 wt%, no more than 40 wt%, no more than 30 wt%, no more than 20 wt%, no more than 10 wt%, no more than 5 wt%, no more than 2 wt% or no more than 1 wt%, based on the total weight of the ethylenically unsaturated monomer (a).

[0102] Typically, the amount of the vinyl ester and / or vinyl ether monomer present may be no more than 18 wt%, no more than 16 wt%, no more than 14 wt%, no more than 12 wt%, no more than 10 wt%, no more than 8 wt%, no more than 6 wt%, no more than 4 wt%, no more than 2 wt% or no more than 1 wt%, based on the total weight of the ethylenically unsaturated monomer (a).

[0103] The amount of the ethylenically unsaturated silane compound present may be no greater than 10 wt%, no greater than 8 wt%, no greater than 6 wt%, no greater than 4 wt%, no greater than 2 wt% or no greater than 1 wt%, based on the total weight of the ethylenically unsaturated monomer (a). In particular, the amount of the ethylenically unsaturated silane compound present may be 0.05 - 5.0 wt%, preferably 0.3 - 2.0 wt%, more preferably 0.3 - 1.0 wt%, based on the total weight of the ethylenically unsaturated monomer (a).

[0104] Typically, the amount of the amide of the ethylenically unsaturated acid present may be no greater than 18 wt%, no greater than 16 wt%, no greater than 14 wt%, no greater than 12 wt%, no greater than 10 wt%, no greater than 8 wt%, no greater than 6 wt%, no greater than 4 wt%, no greater than 2 wt% or no greater than 1 wt%, based on the total weight of the ethylenically unsaturated monomer (a).

[0105] In addition, the amount of the monomer c) having at least two non-conjugated ethylenically unsaturated groups present in the monomer mixture for preparing the shell of the core-shell polymer latex particles of the present invention may be 0.1 - 6.0 wt%, preferably 0.1 - 3.5 wt%, based on the total weight of the ethylenically unsaturated monomers. Typically, the amount of these monomers present may be no greater than 6 wt%, no greater than 4 wt%, no greater than 2 wt%, no greater than 1 wt%, based on the total weight of the ethylenically unsaturated monomers in the monomer mixture for preparing the shell of the core-shell polymer latex particles of the present invention.

[0106] In the monomer mixture for preparing the shell of the core-shell particles of the present invention, the typical amount of the monomer b) present is 0.1 - 16 wt%, based on the total weight of the monomers in the mixture. The amount of the monomer bi) present may be at most 15 wt%, at most 14 wt%, at most 13 wt%, at most 12 wt%, at most 11 wt%, at most 10 wt%, at most 9 wt%, at most 8 wt%, at most 7 wt%, at most 6 wt%, at most 5 wt%, at most 4 wt%, at most 3 wt%, at most 2 wt%, at most 1 wt%. As described above, it is preferred that the monomer bi) is absent in the monomer mixture for preparing the shell of the core-shell particles according to the present invention.

[0107] In the case where the monomer bii) is selected from ethylenically unsaturated carboxylic acids and ethylene oxide-functional ethylenically unsaturated compounds, preferably as defined above, the amount of these compounds present is 0.05 - 10 wt%, in particular 0.1 - 10 wt% or 0.05 - 7 wt%, preferably 0.1 - 9 wt%, more preferably 0.1 - 8 wt%, even more preferably 1 - 7 wt%, most preferably 2 - 7 wt%, based on the total weight of the monomers for preparing the shell of the core-shell particles. Thus, the amount of the ethylenically unsaturated carboxylic acid monomer or the ethylene oxide-functional ethylenically unsaturated monomer present can be at least 0.01 wt%, at least 0.05 wt%, at least 0.1 wt%, at least 0.3 wt%, at least 0.5 wt%, at least 0.7 wt%, at least 0.9 wt%, at least 1 wt%, at least 1.2 wt%, at least 1.4 wt%, at least 1.6 wt%, at least 1.8 wt%, at least 2 wt%, at least 2.5 wt% or at least 3 wt%. Similarly, the amount of the ethylenically unsaturated acid monomer or the ethylene oxide-functional ethylenically unsaturated monomer present can be not more than 10 wt%, not more than 9.5 wt%, not more than 9 wt%, not more than 8.5 wt%, not more than 8 wt%, not more than 7.5 wt%, not more than 7 wt%, not more than 6.5 wt%, not more than 6 wt%, not more than 5.5 wt% or not more than 5 wt%, based on the total weight of the ethylenically unsaturated monomers for preparing the shell of the core-shell particles according to the present invention. A person skilled in the art will understand any range defined by the explicitly disclosed lower limit and the explicitly disclosed upper limit disclosed herein.

[0108] In the case where the monomer bii) is selected from hydroxy-functional and / or amino-functional ethylenically unsaturated monomers, the amount of these monomers present may be from 0.05 to 18 wt%, in particular from 0.1 to 15 wt% or from 0.05 to 10 wt%, preferably from 0.1 to 12 wt%, more preferably from 1 to 10 wt%, even more preferably from 2 to 8 wt%. Thus, the amount of the hydroxy-functional and / or amino-functional ethylenically unsaturated monomers present may be at least 0.01 wt%, at least 0.05 wt%, at least 0.1 wt%, at least 0.3 wt%, at least 0.5 wt%, at least 0.7 wt%, at least 0.9 wt%, at least 1 wt%, at least 1.2 wt%, at least 1.4 wt%, at least 1.6 wt%, at least 1.8 wt%, at least 2 wt%, at least 2.5 wt% or at least 3 wt%. Similarly, the amount of the hydroxy-functional and / or amino-functional ethylenically unsaturated monomers present may be not more than 18 wt%, not more than 16 wt%, not more than 15 wt%, not more than 14 wt%, not more than 13 wt%, not more than 12 wt%, not more than 11 wt%, not more than 10 wt%, not more than 9.5 wt%, not more than 9 wt%, not more than 8.5 wt%, not more than 8 wt%, not more than 7.5 wt%, not more than 7 wt%, not more than 6.5 wt%, not more than 6 wt%, not more than 5.5 wt% or not more than 5 wt%, based on the total weight of the ethylenically unsaturated monomers used to make the shell of the core-shell particles according to the invention. A person skilled in the art will understand any range defined by the explicitly disclosed lower and upper limits disclosed herein.

[0109] The monomer composition for making the core of the core-shell particles according to the invention is not particularly limited, provided that the monomers are selected such that no internal crosslinking of the core occurs. Thus, the monomer mixture for making the core may not contain monomers having a plurality of non-conjugated ethylenically unsaturated groups in the molecule. Conjugated dienes may be present, but it is preferred to select the polymerization conditions to avoid gelation of the core portion, preferably by using a molecular weight regulator such as an alkyl mercaptan during the emulsion polymerization process.

[0110] In particular, the monomers for preparing the core of the core-shell particles according to the present invention may be selected from the monomers a) described above for the monomer mixture of the shell of the core-shell particles according to the present invention. Preferably, the monomer mixture for manufacturing the core comprises 50-100 wt% of (meth)acrylic acid alkyl ester monomers, based on the total weight of the monomers for manufacturing the core of the core-shell particles according to the present invention. Preferably, the alkyl group contains 1-20 carbon atoms, more preferably 2-12 carbon atoms, even more preferably 3-10 carbon atoms and most preferably 4-8 carbon atoms. Thus, the amount of (meth)acrylic acid alkyl ester monomers present in the mixture for polymerizing the core of the core-shell particles according to the present invention may be at least 55 wt%, at least 60 wt%, at least 65 wt%, at least 70 wt%, at least 75 wt%, at least 80 wt%, at least 82 wt%, at least 85 wt%, at least 87 wt%, at least 90 wt%, based on the total weight of the monomers for manufacturing the core of the core-shell particles according to the present invention. The remaining monomers may be particularly selected from conjugated dienes, vinyl aromatic monomers, ethylenically unsaturated amides, ethylenically unsaturated nitriles, (meth)acrylic acid alkoxyalkyl esters, vinyl esters and vinyl ethers, as defined above for the monomer a) of the shell of the core-shell particles according to the present invention.

[0111] In particular, the amount of conjugated diene present may be no more than 90 wt%, no more than 80 wt%, no more than 70 wt%, no more than 60 wt%, no more than 50 wt%, no more than 40 wt%, no more than 30 wt%, no more than 20 wt%, no more than 10 wt%, no more than 2 wt%, based on the total weight of the monomers for manufacturing the core of the core-shell particles according to the present invention. In particular, no conjugated diene may be present.

[0112] In particular, the amount of vinyl aromatic compound present may be no more than 20 wt%, no more than 18 wt%, no more than 16 wt%, no more than 14 wt%, no more than 12 wt%, no more than 10 wt%, no more than 8 wt%, no more than 6 wt%, no more than 4 wt%, no more than 2 wt%, based on the total weight of the monomers for manufacturing the core of the core-shell particles according to the present invention. In particular, no vinyl aromatic compound may be present.

[0113] In particular, the amount of ethylenically unsaturated amide present may be no more than 20 wt%, no more than 18 wt%, no more than 16 wt%, no more than 14 wt%, no more than 12 wt%, no more than 10 wt%, no more than 8 wt%, no more than 6 wt%, no more than 4 wt%, no more than 2 wt%, based on the total weight of the monomers for manufacturing the core of the core-shell particles according to the present invention. In particular, no ethylenically unsaturated amide may be present.

[0114] In particular, the amount of vinyl ester or ether present may be no greater than 20 wt%, no greater than 18 wt%, no greater than 16 wt%, no greater than 14 wt%, no greater than 12 wt%, no greater than 10 wt%, no greater than 8 wt%, no greater than 6 wt%, no greater than 4 wt%, no greater than 2 wt%, based on the total weight of the monomers of the core for producing the core-shell particles according to the invention. In particular, no vinyl ester or ether may be present.

[0115] In particular, the amount of alkoxyalkyl (meth)acrylate present may be no greater than 20 wt%, no greater than 18 wt%, no greater than 16 wt%, no greater than 14 wt%, no greater than 12 wt%, no greater than 10 wt%, no greater than 8 wt%, no greater than 6 wt%, no greater than 4 wt%, no greater than 2 wt%, based on the total weight of the monomers of the core for producing the core-shell particles according to the invention. In particular, no alkoxyalkyl (meth)acrylate may be present.

[0116] In addition, the monomer mixture for producing the core of the core-shell particles according to the invention may contain a small amount of ethylenically unsaturated acid, which is suitably selected from the ethylenically unsaturated acids described above for the monomer mixture of the shell for producing the core-shell particles. Thus, the amount of such ethylenically unsaturated carboxylic acid present may be at most 20 wt%, at most 16 wt%, at most 12 wt%, at most 8 wt%, at most 6 wt%, at most 4 wt%, at most 3 wt%, at most 2 wt%, at most 1 wt%, based on the total weight of the monomers of the core for producing the core-shell particles according to the invention. The ethylenically unsaturated acid may also be completely absent.

[0117] The core of the core-shell particles according to the invention may also be formed from separately produced seed latex, provided that the requirements defined above for the core are met for the seed latex. Alternatively, such seed latex may also be generated in situ at the start of the emulsion polymerization, before the polymerization of the core monomers. Alternatively, such seed latex may also be generated in situ at the start of the emulsion polymerization, before the polymerization of the shell monomers.

[0118] It is also possible for the core-shell polymerization according to the invention to be carried out as a seeded core-shell polymerization, whereby the seed latex may be preformed or formed in situ at the start of the core-shell emulsion polymerization.

[0119] In the core-shell particles of the present invention, the shell can account for 10-90 wt%, preferably 20-80 wt%, more preferably 20-50 wt%, most preferably 25-45 wt% of the total weight of the core-shell particles, and the core can account for 90-10 wt%, preferably 80-20 wt%, more preferably 80-50 wt%, most preferably 75-55 wt%. In the case where the core is formed by preformed seeds or in-situ seeds or the core-shell polymerization is carried out in the presence of preformed or in-situ seeds, when defining the relative amounts of the core and the shell of the core-shell particles according to the present invention, the seeds are calculated as part of the core of the core-shell particles. The seeds can account for 0-100 wt%, preferably 5-30 wt%, more preferably 10-30 wt%, even more preferably 15-30 wt% and most preferably 20-30 wt% of the total weight of the core.

[0120] The monomers used for making the core and for making the shell can be selected such that the glass transition temperature T of the core g is lower than that of the shell, where preferably the T of the core g is lower than 0 °C, preferably lower than -20 °C, and the T of the shell g is higher than 0 °C, preferably higher than 20 °C, which is measured by dynamic mechanical thermal analysis at a fixed frequency of 1 Hz and a heating rate of 3 °C / min.

[0121] In the case where the monomer for making the shell of the core-shell particles according to the present invention contains monomer bii), the core-shell particles according to the present invention are reacted with an ethylenically unsaturated compound having a second functional group reactive with the first functional group of monomer bii) after the termination of the emulsion polymerization to construct a part of the shell of the core-shell particles according to the present invention.

[0122] The amount of the ethylenically unsaturated compound bearing the second functional group is selected so as to be at least 20 mol% of the core-shell particles reacting with the ethylenically unsaturated compound bearing the second functional group, based on the total molar amount of the first functional group introduced into the core-shell particles according to the invention. Preferably, the amount is selected to be at least 25 mol%, at least 30 mol%, at least 35 mol%, at least 40 mol%, at least 42 mol%, at least 45 mol%, at least 47 mol%, at least 50 mol%, at least 52 mol%, at least 55 mol%, at least 57 mol%, or at least 60 mol%, based on the total molar amount of the first functional group in the shell of the core-shell particles reacting with the ethylenically unsaturated compound bearing the second functional group. Likewise, the ethylenically unsaturated compound bearing the second functional group reacts in an amount not greater than 100 mol%, not greater than 90 mol%, not greater than 85 mol%, not greater than 80 mol%, not greater than 77 mol%, not greater than 75 mol%, not greater than 72 mol%, not greater than 70 mol%, not greater than 68 mol%, not greater than 65 mol%, not greater than 62 mol% of the total molar amount of the first functional group present in the shell of the core-shell particles reactive with the ethylenically unsaturated compound bearing the second functional group. Those skilled in the art will understand that all ranges defined by any of the lower or upper limits as defined above are disclosed herein.

[0123] Surprisingly, it has been found that the core-shell latex of the invention can be modified by subsequent reaction with a difunctional monomer to produce a self-supporting elastomeric film, one of the functional groups of which is capable of reacting with a suitable reactive group on the core-shell latex of the invention, and the other of which is capable of reacting, for example by polymerization, in the presence of oxygen or a free radical initiator or a suitable controlled free radical initiator system known in the art such as RAFT, ATRP, MADIX or NMP. Such reactions can be exemplified by: selecting a core-shell latex of the invention having a carboxylic acid functional group; preferably but not necessarily exclusively, such a functional group is located at the surface of the latex particles and it can react with a suitable monomer such as glycidyl methacrylate. In addition, it has been found that such an esterification reaction can be carried out at a pH above 8, or preferably at a pH below 8, preferably at a pH of 7 or lower, more preferably at a pH of 6 or lower, most preferably at a pH of 5 or lower. In addition, such an esterification reaction can be carried out in the presence or absence of a catalyst known in the art such as metal ions, preferably polyvalent metal ions, for example zinc acetate can be used; or a quaternary or ammonium salt can be used, particularly useful being cetyl dimethyl benzyl ammonium chloride, tetrabutyl ammonium hydroxide or tetramethyl guanidine. In addition, the difunctional monomer can react or not react with another monomer in the core-shell latex of the invention.

[0124] The amount of monomer added to functionalize the core-shell latex can be less than the stoichiometric amount required to react with all available groups of the core-shell latex. Alternatively, the amount of monomer added to functionalize the core-shell latex can be greater than the stoichiometric amount required to react with all available groups of the core-shell latex. Preferably, an excess of functional monomer is used, and this excess can be up to 2 times, up to 3 times, or no greater than 4 times the available groups. If there is an excess of functional monomer, efforts should be made to minimize this excess of unreacted monomer in the final latex. This can be achieved by washing the latex with a solvent in which the functional monomer is soluble but the latex particles are insoluble, such a solvent being chloroform. Alternatively, the unreacted difunctional monomer can be retained in the latex.

[0125] The core-shell particles according to the invention can be manufactured by standard seeded or non-seeded emulsion polymerization processes. Particularly suitable for making seeds is the method described in WO2017164726(A1).

[0126] Emulsion (or latex) polymerization can be carried out under an inert atmosphere, such as an inert atmosphere provided by nitrogen or argon, or it can be carried out without an inert atmosphere. A delayed monomer feed (typically containing a chain transfer agent) that defines the core as described above is added to the dispersion of seed particles, and after completion of this monomer feed and a post-cooking period, then a monomer mixture that defines the shell as described above is added using continuous monomer addition (also called a delayed addition scheme). Alternatively, the shell can be produced by adding a single aliquot or a number of aliquots of the desired monomer mixture. Preferably, the components of the monomer mixture containing the delay do not change during addition.

[0127] The core does not contain a crosslinked structure. The shell may or may not form a continuous layer around the core. Preferably, the shell forms a continuous layer around the core. The shell can contain a crosslinked structure. Alternatively, emulsion (or latex) polymerization can be carried out with in-situ seed formation, which is typically produced by adding aliquots of core monomer and polymerizing it, and then adding a delayed monomer when the exotherm of this polymerization is detected. The preferred option is to carry out the core-shell latex polymerization in a continuous manner in a single vessel.

[0128] The process for preparing the above polymer latex can be carried out at a temperature of 0 - 130 °C, preferably 0 - 100 °C, particularly preferably 5 - 70 °C, very particularly preferably 5 - 60 °C, in the absence or presence of one or more emulsifiers, in the absence or presence of one or more colloids and one or more initiators. The temperature includes all values and sub - values therebetween, particularly including 5 °C, 10 °C, 15 °C, 20 °C, 25 °C, 30 °C, 35 °C, 40 °C, 45 °C, 50 °C, 55 °C, 60 °C, 65 °C, 70 °C, 75 °C, 80 °C, 85 °C, 90 °C, 95 °C, 100 °C, 105 °C, 110 °C, 115 °C, 120 °C and 125 °C.

[0129] The initiators that can be used when carrying out the present invention include water - soluble and / or oil - soluble initiators that are effective for the purpose of polymerization. Representative initiators are well - known in the art and include, for example: azo compounds (such as AIBN, AMBN and cyano - valeric acid) and inorganic peroxide compounds such as hydrogen peroxide, persulfates of sodium, potassium and ammonium, percarbonates and perborates, as well as organic peroxide compounds 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.

[0130] The amount of the initiator used is sufficient to initiate the polymerization reaction at a desired rate. Generally, an amount of 0.01 - 5% by weight, preferably 0.1 - 4% by weight of the initiator is sufficient, based on the weight of the total polymer. The amount of the initiator is most preferably 0.01 - 2% by weight, based on the total weight of the polymer. The amount of the initiator includes all values and sub - values therebetween, particularly including 0.01, 0.1, 0.5, 1, 1.5, 2, 2.5, 3, 4 and 4.5% by weight, based on the total weight of the polymer.

[0131] The above - mentioned inorganic and organic peroxide compounds can also be used alone or in combination with one or more suitable reducing agents, as is well - known in the art. Examples of such reducing agents that can be mentioned are sulfur dioxide, alkali metal dithionites, bisulfites of alkali metals and ammonium, thiosulfates, dithionites and formaldehyde sulfoxylates, as well as hydroxylamine hydrochloride, hydrazine sulfate, iron(II) sulfate, copper naphthenate, glucose, sulfonic acid compounds such as sodium methanesulfonate, amine compounds such as dimethylaniline and ascorbic acid. The amount of the reducing agent is preferably 0.03 - 10 parts by weight / part by weight of the polymerization initiator.

[0132] The initiator is present during the polymerization of the initial monomer charge for forming seeds, whether external seeds or in-situ seeds, and the latter scenario is preferred as it has been found that this does not require the addition of additional initiator to the core-shell latex polymerization. Alternatively, additional aliquots of the initiator can be added during the polymerization process or after the delayed monomer completion to reduce the final level of free monomer in the latex.

[0133] Surfactants or emulsifiers suitable for stabilizing the latex particles include those conventional surfactants used in the polymerization process. One or more surfactants can be added to the aqueous phase and / or the monomer phase. The effective amount of surfactant in the seeded method is an amount selected to support the stabilization of the particles as a colloid, minimizing inter-particle contact and preventing coagulation. In a non-seeded method, the effective amount of surfactant is an amount selected to affect the particle size.

[0134] The effective amount of surfactant is an amount selected for any method of producing a seed latex of suitable particle size, whether external or in-situ. In addition, a portion of the surfactant is required to produce a pre-emulsion for both the monomers used to produce the core and / or the monomers used to produce the shell. The total amount of surfactant is such that it maintains a stable latex during the production of both the core and the shell and also during the functionalization of the latex, and it minimizes the nucleation of any new particles.

[0135] Representative surfactants include saturated and ethylenically unsaturated sulfonic acids or their salts, including, for example, unsaturated hydrocarbon sulfonic acids such as vinyl sulfonic acid, allyl sulfonic acid, and methallyl sulfonic acid and their salts; aromatic hydrocarbon acids such as p-styrene sulfonic acid, isopropenylbenzene sulfonic acid, and vinyloxybenzene sulfonic acid and their salts; sulfonated alkyl esters of acrylic and methacrylic acids such as sodium 2-sulfoethyl methacrylate and sodium 3-sulfopropyl methacrylate and their salts and 2-acrylamido-2-methylpropane sulfonic acid and its salts; alkylated diphenyl ether disulfonates, sodium dodecylbenzenesulfonate, and dihexyl esters of sodium sulfosuccinate, sodium alkyl sulfates, sodium alkyl ethoxysulfates, ethoxylated alkylphenols, and ethoxylated alcohols; fatty alcohol (poly) ether sulfates.

[0136] The type and amount of surfactant are typically governed by the number of particles, their size, and their composition. Typically, the amount of surfactant used is 0 - 20 wt%, preferably 0 - 10 wt%, more preferably 0 - 5 wt%, based on the total weight of the monomers. The amount of surfactant includes all values and sub-values therebetween, particularly including 0, 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, and 19 wt%, based on the total weight of the monomers. According to one embodiment of the present invention, the polymerization is carried out in the absence of a surfactant.

[0137] Instead of or in addition to the above surfactants, various protective colloids can also be used. 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. Usually, these protective colloids are used in an amount of 0 - 10, preferably 0 - 5, more preferably 0 - 2 parts by weight, based on the total weight of the monomers. The amounts of the protective colloids include all values and sub - values therebetween, especially including 1, 2, 3, 4, 5, 6, 7, 8, and 9 wt%, based on the total weight of the monomers.

[0138] In the case where the polymer latex composition is used for dip - molding applications, it is preferred that the polymer latex composition has a certain maximum electrolyte stability as determined by the critical coagulation concentration of less than 30 mmol / l calcium chloride, preferably less than 25 mmol / l, more preferably less than 20 mmol / l, and most preferably less than 10 mmol / l (measured at pH 10 and 23 °C for a total solids content of 0.1% of the composition).

[0139] It is often feasible to conduct the emulsion polymerization additionally in the presence of buffer substances and chelating agents. Suitable substances are, for example, alkali metal phosphates and pyrophosphates (buffer substances) and alkali metal salts of ethylenediaminetetraacetic acid (EDTA) or hydroxy - 2 - ethylenediaminetriacetic acid (HEEDTA) (as chelating agents). The amounts of the buffer substances and chelating agents are usually 0.001 - 1.0 wt%, based on the total amount of the monomers.

[0140] In embodiments of the present invention, it has been found that the presence of a buffer is not necessary for producing a stable latex, and thus the final pH of a typical core - shell latex is less than 5, typically it is about 3.

[0141] Furthermore, it can be advantageous to use a chain transfer agent (modulator) in the emulsion polymerization. Typical reagents are, for example, organic sulfur compounds such as thioesters, 2 - mercaptoethanol, 3 - mercaptopropionic acid, and C 1 -C 12 alkyl mercaptans, n - dodecyl mercaptan, and tert - dodecyl mercaptan are preferred. When present, the amount of the chain transfer agent is usually 0.05 - 3.0 wt%, preferably 0.2 - 2.0 wt%, based on the total weight of the monomers used.

[0142] In addition, it can be beneficial to introduce partial neutralization in the polymerization process. Those skilled in the art will understand that by appropriately selecting this parameter, the necessary control can be achieved.

[0143] Various other additives and ingredients can be incorporated to prepare the latex compositions of the present invention. Such additives include, for example: defoamers, wetting agents, thickeners, plasticizers, fillers, pigments, dispersants, optical brighteners, crosslinking agents, accelerators, antioxidants, biocides and metal chelating agents. Known defoamers include silicone oils and acetylene glycols. Commonly known wetting agents include alkylphenol ethoxylates, alkali metal dialkyl sulfosuccinates, acetylene glycols and alkali metal alkyl sulfates. Typical thickeners include polyacrylates, polyacrylamides, xanthan gum, modified celluloses or particulate thickeners such as silica and clay. Typical plasticizers include mineral oil, liquid polybutene, liquid polyacrylate and lanolin. Zinc oxide is a suitable ionic crosslinking agent. Titanium dioxide (TiO 2 ), calcium carbonate and clay are typical fillers used. Known accelerators and secondary accelerators include dithiocarbamates such as zinc diethyldithiocarbamate, zinc dibutyldithiocarbamate, zinc diphenyldithiocarbamate, zinc pentamethylenedithiocarbamate (ZPD), xanthates, thiurams such as tetramethylthiuram monosulfide (TMTM), tetramethylthiuram disulfide (TMTD), tetraethylthiuram disulfide (TETD), dipentamethylenethiuram hexasulfide (DPTT) and amines such as diphenylguanidine (DPG), di-o-tolylguanidine (DOTG), o-tolylbiguanide (OTBG).

[0144] As described above, the present invention also relates to an elastomeric film made from the aqueous dispersion according to the present invention.

[0145] One advantage of the present invention is that the core-shell polymer latex particles according to the present invention allow the preparation of elastomeric films without using conventional sulfur vulcanization, which is embodied in adding elemental sulfur and a suitable accelerator to a blend containing polymer latex particles. Nor is it necessary to add polyvalent cations such as zinc compounds to the latex blend used to manufacture the elastomeric film.

[0146] Thus, in the process of manufacturing a self-supporting elastomeric film, as defined above in the Summary of the Invention, it is preferred that step a) neither includes adding elemental sulfur and an accelerator to the composition for sulfur vulcanization nor includes adding a zinc compound to the composition; thus, it is preferred that the pH of the composition in step a) is at most 8.5, preferably at most 8.0, preferably at most 7.5, more preferably at most 7.

[0147] The elastomeric film can be obtained by casting, dip molding, spraying or knife coating.

[0148] Before or after separating the elastomeric film from the substrate, the elastomeric film can be heat-treated at a temperature of 40 °C - 180 °C, preferably 60 °C - 100 °C, more preferably 75 °C - 100 °C. Thus, according to the present invention, the elastomeric film is preferably self-supporting and substantially free of sulfur crosslinking and substantially free of ionomer crosslinking.

[0149] Furthermore, the present invention also relates to an article comprising the elastomeric film as defined above. According to the present invention, the elastomeric film can have a first and a second outer surface and a core between the first and the second outer surfaces, wherein the degree of crosslinking between the polymer particles at the first and the second outer surfaces is higher than the degree of crosslinking in the core of the film.

[0150] The article according to the present invention can be selected from disposable gloves, including surgical gloves and examination gloves, industrial gloves, household gloves, fabric-supported gloves, medical devices such as catheters, condoms and female condoms or the article comprises an adhesive component for an energy battery, which energy battery is preferably a lithium-ion-containing storage battery.

[0151] The present invention will now be further illustrated with reference to the following examples. Examples

[0152] Determination of physical parameters:

[0153] Latex (also referred to as emulsion or dispersion) is characterized by determining the total solids content (TSC), pH value and z-average particle size. In addition, the tensile properties of the final film were tested both before and after cutting and re-bonding. The film which was cut in half and then the two halves were then held together and which was able to exhibit a certain tensile strength when the two halves thus joined were subsequently separated was said to be self-healing.

[0154] Determination of total solids content (TSC):

[0155] The TSC of the dispersion sample was measured gravimetrically. The latex was gently stirred by hand vortexing the contents. Three aliquots of the latex (~2.0 g) were pipetted into pre-weighed aluminum dishes and weighed before drying in a pre-heated oven set at 80 °C for 24 h. After cooling to room temperature, the final weight was then determined. The TSC was calculated as follows:

[0156] TSC (%) = (m o / m i ) × 100 (1)

[0157] Wherein m o and m i are the weight of the dried sample and the weight of the latex sample, respectively. The average value of the three samples tested was used.

[0158] Determination of pH value:

[0159] The pH of the dispersion was measured using a CyberScan pH meter.

[0160] Determination of particle size (PS):

[0161] Dynamic light scattering

[0162] Dynamic light scattering (DLS) was performed using a Malvern Zetasizer NanoZS90 (Malvern Instruments Ltd.) equipped with a 20 mW He-Ne laser. Typically, the final concentration of the sample was 0.01 wt%, to ensure that the photon counting rate remained between 100 - 200 kcps (kilo counts per second). The measurements were carried out at 25 °C. The values were recorded as the z-average particle size (dz).

[0163] Transmission electron microscopy

[0164] Transmission electron microscopy was performed using a Philips CM200 instrument operating at 200 kV. For a typical formulation, 0.4 mL of 0.2 wt% latex was mixed with 1.6 mL of 2 wt% phosphotungstic acid (H 3 O 40 PW 12 ) at room temperature for at least 15 - 20 minutes. Phosphotungstic acid was used as a negative stain for the particle specimens. The final mixture concentration used was approximately 0.04 wt%. One drop (μL) of the mixture was pipetted onto a 300 mesh holey carbon grid copper (Agar Scientific Ltd.) and left for 2 minutes, then the excess liquid was drained off (using thin paper to absorb the excess liquid). The sample was left to dry in a desiccator overnight. At least 100 particles were analyzed to calculate the number average diameter (d TEM ) using the following equation:

[0165] d TEM = Σn i d i / Σn i (2)

[0166] Where d i is the diameter of the particles in the i-th group, and n i is the number of particles in the i-th group.

[0167] The coefficient of variation (CV) was calculated from the standard deviation (SD) using equation (3):

[0168] CV =(100×SD) / d TEM (3)

[0169] In the following examples, the CV is given in parentheses after the average particle size value.

[0170] Potentiometric titration of latex samples

[0171] A Mettler Toledo DL15 titrator was used to determine the carboxylic acid content of the samples. For a typical formulation, 1 wt% (0.88 g of 45 wt%) of the dispersion was mixed in 40 mL of 0.1 M aqueous NaCl solution. The diluted latex was mechanically stirred for 15 seconds at room temperature and then titrated against a standardized NaOH (1.0 M) solution.

[0172] Zeta potential measurement

[0173] Zeta potential measurements were made using a Malvern Zetasizer NanoZS90 (Malvern Instruments Ltd.) instrument. A latex with a concentration of 0.01 wt% was prepared, which contained NaNO 3 (0.001 wt%). The diluted mixture was transferred to the measurement cell using a 1 mL plastic syringe. The average zeta potential and electrophoretic mobility obtained from the software were then averaged over three measurements. The measurement temperature was set at 25 °C.

[0174] Determination of dynamic mechanical properties

[0175] The viscoelastic behavior of the materials under study was measured using a TA-Q800 Instrument dynamic mechanical thermal analyzer in tensile mode. The film specimens were in the form of rectangular strips with dimensions of 15 mm × 5.5 mm × 0.5 mm. The measurements were carried out at temperatures from -110 °C to 200 °C, a heating rate of 3 °C min-1, and a frequency of 1 Hz. The data obtained measured the storage modulus (E’), loss modulus (E”), and tanδ value (E″ / E′) as a function of temperature from -110 °C to 200 °C.

[0176] Determination of tensile properties:

[0177] The tensile properties of the specimens were measured using a Hounsfield H10KS tensile tester (2000 N load cell) equipped with a laser extensometer. The film was cut into dumbbell shapes using a steel die, which had a length of 75.0 mm and a width of 4.0 mm at its narrowest part and extended over a length of 25 mm. Before measurement, the film was conditioned in a climate-controlled room at 25 °C (±2) and 50% (±5) relative humidity for 24 hours. The extension rate was determined at a constant crosshead speed of 500 mm / min.

[0178] The measurements were carried out at 25 °C and 50% RH. The reported results are the average values obtained from 3 - 5 measurements.

[0179] Polymerization apparatus

[0180] A 2 L five-necked reaction glass vessel was immersed in a water bath equipped with a thermostat; the reactor lid had suitable entry points for a mechanical stirrer, a condenser for the cooling system, an argon, and a reactant feed inlet. The stirrer rate indicator was kept constant at 250 rpm. The polymerization temperature was maintained at 75 °C. The reactants for the emulsion polymerization were fed at a rate of ~5.50 g min -1 (for core growth) and ~3.21 g min -1 (for the shell growth phase) using a Watson-Marlow 505S peristaltic pump.

[0181] BA = n-butyl acrylate

[0182] ACN = acrylonitrile

[0183] BDDA = 1,4-butanediol diacrylate

[0184] MAA = methacrylic acid

[0185] t-ddm = tert-dodecyl mercaptan

[0186] GMA = glycidyl methacrylate

[0187] KPS = potassium persulfate

[0188] TSC = total solids content

[0189] PS = particle size

[0190] DLS = dynamic light scattering

[0191] TEM = transmission electron microscopy

[0192] DMTA = dynamic mechanical thermal analysis

[0193] Hereinafter, the terms "latex" and "dispersion", "emulsion" or "heterogeneous" are used interchangeably.

[0194] Hereinafter, all parts and percentages are by weight unless otherwise specified.

[0195] Example 1: Preparation of seed latex

[0196] In the apparatus described in detail above, deionized water (300 g) was added to the reaction vessel and purged with argon for 20 min. Then an aqueous solution of surfactant Aerosol (sodium dihexyl sulfosuccinate, supplied by Solvay) Aerosol (Supplied as 14 g dissolved in 76 g deionized water). After stirring for 5 minutes under an argon stream and at a constant stirring rate of 250 rpm, butyl acrylate monomer (54.0 g, 0.42 mol) was added and stirred for 5 minutes. Finally, an initiator solution containing potassium persulfate (1.37 g, dissolved in 54 g deionized water) was added (time = 0). After polymerization at 75 °C for 60 minutes, seed particles with an average particle size of 45 nm (DLS) and 43 (15) nm (TEM) were obtained.

[0197] It has been found important to control the target particle size of the seeds to ~50 nm in order to obtain the formation of monodisperse final core - shell particles with a diameter of ~100 nm. The results of the seed particles are given in Table 1.

[0198] Example 2: Preparation of core latex

[0199] The core nanoparticles were prepared using the seed latex of Example 1. At the completion of the seed stage, a mixture of surfactant (Aerosol MA - 80), butyl acrylate, tert - dodecyl mercaptan, and a pre - emulsion of potassium persulfate in deionized water was continuously added at a feed rate of 5.50 g min -1 using a metering pump. After the addition of the pre - emulsion to the reaction vessel was completed, the polymerization continued for 135 minutes to obtain the core latex.

[0200] The pre - emulsion contained the following: deionized water (171.45 g), tert - dodecyl mercaptan (0.085 g), Aerosol MA - 80 (2.97 g), and butyl acrylate (237.50 g, 2.13 mol), which were mixed and stirred for 30 minutes before the start of the delayed addition.

[0201] The average particle size of the obtained core particles was 79 nm (DLS) and 80 (28) nm (TEM). The results of the core particles are given in Table 1.

[0202] Example 3: Preparation of core - shell particles with a cross - linked shell

[0203] Using a setting of 3.21 g min -1A metering pump with a feed rate of was used to add a pre-emulsion to the latex of Example 2. The pre-emulsion contained Aerosol MA-80 (2.97 g), tert-dodecyl mercaptan (0.085 g), and a shell comonomer solution (237.51 g, containing butyl acrylate (64 wt%, 152.00 g), acrylonitrile (30 wt%, 71.25 g), methacrylic acid (5 wt%, 11.88 g), and 1,4-butanediol diacrylate (1 wt%, 2.38 g)). After the reaction was completed (a total of 4 hours at 75 °C), the latex was immediately cooled in an ice container. Then it was filtered through a sieve (28 μm) to separate any coagulum. The average particle size of the obtained core-shell particles was 76 nm (DLS) and 63 (16) nm (TEM). The results of the core-shell particles are given in Table 1.

[0204] Example 4: (Comparative) Preparation of core-shell particles without shell crosslinking

[0205] Using 3.21 g min -1 A metering pump with a feed rate of was used to add a pre-emulsion to the latex of Example 2. The pre-emulsion contained Aerosol MA-80 (2.97 g), tert-dodecyl mercaptan (0.085 g), and a shell comonomer solution (237.51 g, containing butyl acrylate (65 wt%, 154.38 g), acrylonitrile (30 wt%, 71.25 g), and methacrylic acid (5 wt%, 11.88 g)). After the reaction was completed (a total of 4 hours at 75 °C), the latex was immediately cooled in an ice container. It was filtered through a sieve (28 μm) to separate any coagulum. The average particle size of the obtained core-shell particles was 97 nm (DLS) and 93 (20) nm (TEM). The results of the core-shell particles are given in Table 1.

[0206] Example 5: Preparation of core-shell particles containing a crosslinked shell

[0207] Using 3.21 g min -1A metering pump with a feed rate of was used to add a pre-emulsion to the replicated latex of Example 2. The pre-emulsion contained Aerosol MA-80 (2.97 g), tert-dodecyl mercaptan (0.085 g), and a shell comonomer solution (237.51 g, containing butyl acrylate (64 wt%, 154.38 g), acrylonitrile (30 wt%, 71.25 g), methacrylic acid (5 wt%, 11.88 g), and 1,4-butanediol diacrylate (1 wt%, 2.38 g)). After the reaction was completed (a total of 4 hours at 75 °C), the latex was immediately cooled in an ice container. It was filtered through a sieve (28 μm) to separate any coagulum. The average particle size of the obtained core-shell particles was 95 nm (DLS) and 91(15) nm (TEM). The results of the core-shell particles are given in Table 1.

[0208] Example 6: Preparation of core-shell particles containing a crosslinked shell

[0209] Using 3.21 g min -1 A metering pump with a feed rate of was used to add a pre-emulsion to the replicated latex of Example 2. The pre-emulsion contained Aerosol MA-80 (2.97 g), tert-dodecyl mercaptan (0.085 g), and a shell comonomer solution (237.51 g, containing butyl acrylate (66 wt%, 156.75 g), acrylonitrile (28 wt%, 66.5 g), methacrylic acid (5 wt%, 11.88 g), and 1,4-butanediol diacrylate (1 wt%, 2.38 g)). After the reaction was completed (a total of 4 hours at 75 °C), the latex was immediately cooled in an ice container. It was filtered through a sieve (28 μm) to separate any coagulum. The average particle size of the obtained core-shell particles was 96 nm (DLS) and 84(14) nm (TEM). The results of the core-shell particles are given in Table 1.

[0210] Example 7: Preparation of core-shell particles containing a crosslinked shell

[0211] Using 3.21 g min -1A metering pump with a feed rate of was used to add a pre-emulsion to the replicated latex of Example 2. The pre-emulsion contained Aerosol MA-80 (2.97 g), tert-dodecyl mercaptan (0.085 g), and a shell comonomer solution (237.51 g, containing butyl acrylate (71 wt%, 168.63 g), acrylonitrile (23 wt%, 54.63 g), methacrylic acid (5 wt%, 11.88 g), and 1,4-butanediol diacrylate (1 wt%, 2.38 g)). After the reaction was completed (a total of 4 hours at 75 °C), the latex was immediately cooled in an ice container. It was filtered through a sieve (28 μm) to separate any coagulum. The average particle size of the obtained core-shell particles was 93 nm (DLS) and 82 (24) nm (TEM). The results of the core-shell particles are given in Table 1.

[0212] Example 8: Preparation of Core-Shell Particles Containing a Crosslinked Shell

[0213] Using a metering pump with a feed rate of 3.21 g min -1 A metering pump with a feed rate of was used to add a pre-emulsion to the replicated latex of Example 2. The pre-emulsion contained Aerosol MA-80 (2.97 g), tert-dodecyl mercaptan (0.085 g), and a shell comonomer solution (237.51 g, containing butyl acrylate (74 wt%, 175.75 g), acrylonitrile (20 wt%, 44.5 g), methacrylic acid (5 wt%, 11.88 g), and 1,4-butanediol diacrylate (1 wt%, 2.38 g)). Then the latex was kept at 75 °C for an additional 55 minutes to complete the polymerization. After the reaction was completed, the latex was immediately cooled in an ice container and then filtered through a sieve (28 μm) to separate any coagulum. The average particle size of the obtained core-shell particles was 90 nm (DLS) and 83 (20) nm (TEM). The results of the core-shell particles are given in Table 1.

[0214] Table 1 Latex Properties

[0215]

[0216] a = Nominal volume fraction of the core present, based on 100% conversion.

[0217] b = z-average diameter measured by DLS at pH 5.0.

[0218] c = Number-average diameter of the particles measured by TEM (the number in parentheses is the coefficient of variation).

[0219] d = Shell thickness, which was calculated from the DLS data using the following formula:

[0220] (dz (cs) -dz (c) ) / 2, (4)

[0221] where dz (cs) and dz (c) are the z-average diameters of the final core-shell and core nanoparticles, respectively.

[0222] NA = Not applicable

[0223] Example 9: Influence of the pH response and the shell of crosslinked core-shell polymer particles of the examples

[0224] During the preparation of coated and dip-coated films made from the polymers of the present invention, it may be necessary to increase the pH of the latex to enhance storage stability, or incorporate metals, preferably polyvalent metals such as zinc ions (in the form of zinc oxide), to form an ionomer crosslink in order to form a self-supporting nitrile latex film, which is known in the prior art, see for example "Crosslinking in carboxylated nitrile rubber dipped films", Kells, A. and Groves, B. (paper presented at Latex 2006: Frankfurt, Germany, 24-25 January 2006). Additionally, the viscosity-pH response of the latex is critical for the quality of cast or dip-coated films formed from such carboxylated latexes.

[0225] The d z value of the nanoparticles was measured as a function of pH by dynamic light scattering, and the results are shown in Figure 1 :

[0226] Figure 1 It is shown that the presence of the crosslinked shell renders any pH response of the latex ineffective, and visual reference indicates that while all examples are free-flowing liquids at pH 3, Example 4 forms a gel at pH 8, while Example 5 remains a free-flowing latex as an example.

[0227] Example 10: Evaluation of available methacrylic acid by potentiometric titration

[0228] The measured methacrylic acid (MAA) (wt%) value is determined from the titration data by applying the following equation:

[0229] MAA (wt%) = ((V KOH × C KOH ) / (m 分散体 × TSC (wt%) 分散体 ) × Mw (MAA) (3)

[0230] MAA (wt%) = (mass of neutralized MAA / mass of solid polymer) × 100 (4)

[0231] From this, VKOH and C KOH are the volume of KOH at the neutralization point (from the maximum slope point of the graph of Ph versus added KOH) and the concentration of the KOH solution, respectively. M 分散体 is the mass of the polymer dispersion used for titration (weight solids percentage of the polymer dispersion used). Mw( MAA ) is the molecular weight of MAA, which is 86.09 g mol -1 .

[0232] Table 2 Potentiometric titration data

[0233]

[0234] a = the nominal concentration of MAA in the whole particle, based on the composition.

[0235] b = the measured value of the MAA concentration, calculated from the titration data.

[0236] Apparatus for functionalizing the shell of a core - shell latex

[0237] Place one - third of a 1 L round - bottomed conical glass container in a paraffin oil bath at 40 °C. Magnetically stir the reaction mixture, and the stirring rate is controlled by setting the magnetic stirrer plate at a constant rate of 250 rpm. The nanoparticle dispersion is functionalized with glycidyl methacrylate; the amount (g) of glycidyl methacrylate added to the latex to be functionalized is shown in Table 3.

[0238] The degree of glycidyl methacrylate functionalization achieved is detected using acid - base potentiometric titration by the decrease in wt% of detectable methacrylic acid in the formed functionalized core - shell latex. That is, it detects the amount of methacrylic acid that has not undergone an esterification reaction with glycidyl methacrylate functionalization. The titration data (Table 3) shows the decrease in the methacrylic acid content obtained.

[0239] Example 11: Functionalization of Example 3

[0240] The mixture of Example 3 (300 g, 10 wt%) was adjusted to pH 5.0 using 0.5 M aqueous KOH solution. The mixture was initially stirred at 250 rpm for 15 min before being added to a 1 L flask. Then an aliquot of glycidyl methacrylate (5.94 g, 4.18 mol%) was added to the flask, and the mixture was heated at 40 °C at 250 rpm for 8 h. The unreacted glycidyl methacrylate was removed using a separatory funnel. The nanoparticle dispersion was washed twice with 200 mL of chloroform. The chloroform remaining in the glycidyl methacrylate-functionalized latex was removed by evaporation using a rotary evaporator at a temperature of 25 °C. The thus purified latex was then concentrated to 12 wt% using a rotary evaporator. The characteristic data of the functionalized core-shell of Example 9 obtained were given in Table 3, where it was compared with the unfunctionalized core-shell precursor latex of Example 3. It can be seen that after functionalization, a decrease in the detected wt% of methacrylic acid was detected, which decreased from 3.8 wt% to 1.7 wt% respectively. This difference was then used to calculate the mol% of glycidyl methacrylate now present on the latex particles after the reaction between the carboxylic acid groups on the latex particles and the epoxy groups on glycidyl methacrylate, which was 2.5 mol% in the case of Example 9.

[0241] Example 12: Functionalization of Example 5

[0242] The mixture of Example 5 (300 g, 10 wt%) was adjusted to pH 5.0 using 0.5 M aqueous KOH solution. The mixture was initially stirred at 250 rpm for 15 min before being added to a 1 L flask. Then an aliquot of glycidyl methacrylate (53.42 g, 2.41 mol%) was added to the flask, and the mixture was heated at 40 °C at 250 rpm for 8 h. The unreacted glycidyl methacrylate was removed using a separatory funnel. The nanoparticle dispersion was washed twice with 200 mL of chloroform. The thus purified latex was then concentrated to 12 wt% using a rotary evaporator. The chloroform remaining in the glycidyl methacrylate-functionalized latex was removed by evaporation using a rotary evaporator at a temperature of 25 °C. The characteristic data of Example 10 obtained before (i.e., Example 5) and after functionalization with glycidyl methacrylate were given in Table 3. The mol% of glycidyl methacrylate now present on the latex particles was 1.5 mol%.

[0243] Example 13

[0244] This was a repetition of Example 12, except that the latex of Example 8 was used instead of the latex of Example 5.

[0245] Table 3 Titration data of nanoparticles before and after functionalization

[0246]

[0247] a = pH of the final dispersion.

[0248] b = MAA content, based on potentiometric titration data.

[0249] c = GMA (mol%) added to the latex particles.

[0250] The stability of the functionalized latex particles was then evaluated by measuring the z-average diameter (d z ), the zeta potential (ξ), and the number-average diameter (d TEM ) from TEM. Without wishing to be bound by theory, it is believed that the constancy of these parameters is important for enabling the preparation of similar membranes. Table 4 shows the characteristic data of the latex particles before and after functionalization with glycidyl methacrylate, respectively.

[0251] Table 4 Characteristic data of the latex before and after functionalization

[0252]

[0253] a = Value determined by DLS.

[0254] b = Number-average diameter measured by TEM (at least 100 particles) (the number in parentheses is the coefficient of variation).

[0255] c = Zeta potential value measured at pH 5.0. Sample concentration 0.01 wt%, and 0.001 M sodium nitrate NaNO 3

[0256] d = Value determined by DLS.

[0257] e = Zeta potential value measured at pH 6.0. Sample concentration 0.01 wt%, and 0.001 M sodium nitrate NaNO 3

[0258] Table 4 shows that both d z and d TEM increased only minimally after functionalization. Without wishing to be bound by theory, this is believed to reflect the functionalization of the surface carboxylic acid groups. Low polydispersity values were observed for all functionalized dispersions, and the zeta potential values were not significantly different before and after functionalization.

[0259] TEM micrographs of the core-shell latex samples deposited on carbon grids (note that some deformation may occur as the particles dry) and subsequently stained with phosphotungstic acid confirmed that the functionalization procedure did not perceptibly alter the morphology of the latex particles.

[0260] Example 14: Preparation of cast films and determination of their glass transition temperatures

[0261] The dispersion (60 g of 12 wt%) was stirred at 200 rpm for 15 minutes and then poured into a glass mold (100×125 mm) surrounded by a removable stainless-steel wall (5 mm high). The surface of this mold had been previously cleaned and then sprayed with an anti-stick aerosol spray of Ambersil Dry PTFE film (supplied by CRC Industries UK Ltd) to prevent the dry film from adhering to the mold surface. Then the mold surface was dried to prevent Ambersil from mixing into the latex. Then the cast latex film was placed in a circulating air oven at 25 °C for 3 days. The film was dried at atmospheric pressure in a humidity-controlled environment (50% RH). The typical average thickness of the dried film was 550 - 600 μm, which was measured with a set of calipers.

[0262] To anneal the films, they were further dried in a circulating air oven at 90 °C for 24 h.

[0263] Dynamic mechanical thermal analysis (DMTA) experiments were performed on the cast films using a TA-Q800 Instrument dynamic mechanical thermal analyzer operating in tensile mode. The samples were in the form of rectangular strips with dimensions of 15 mm×5.5 mm×0.5 mm, and the measurements were carried out at a heating rate of 3 °C min -1 during a temperature ramp from -110 °C to 200 °C and at a frequency of 1 Hz. The data obtained measured the storage modulus (E’), loss modulus (E’’), and tanδ value (E″ / E′) as a function of temperature.

[0264] The Tg values of the obtained core-shell polymers are given in Table 5.

[0265] Table 5 Characteristic data of latex films

[0266]

[0267] a = latex pH during film casting

[0268] b = annealing temperature of the film

[0269] c = Tg (c) and Tg (s) are the core and shell glass transition temperatures of the measured GMA-functionalized films, respectively, determined from the tand maximum.

[0270] d = Young's modulus

[0271] e = breaking stress

[0272] f = breaking strain

[0273] ND = not detected, NM = not measured

[0274] Example 15: Self-healing property of the film of the present invention

[0275] Diligent observation noted that when a cast film sample was cut into 2 pieces, it could re-bond by keeping the interface of the two halves together, and this self-healing process took only a few minutes at room temperature.

[0276] To improve the self-healing process and thus enhance the physical properties of the self-healing film, the cut sample was heated to above the Tg of the latex film (s) . Figure 2a The results obtained when dumbbell films of non-functionalized Example 3 and functionalized Example 11 were cut in half using a blade are shown. The upper surface of the cut dumbbell was immediately marked with a pen at 2 points, and then the two halves were re-bonded by pressing them together at room temperature for 60 seconds, and then the sample was annealed in a circulating air oven at 40 °C for 24 hours.

[0277] Figure 2a Shown are (a) before cutting, (b) the dumbbell cut into 2 pieces and the upper surface of the dumbbell marked, (c) re-connected by pressing for 60 seconds, (d) after annealing at 40 °C for 24 hours. It should be noted that Example 3 (non-functionalized film) failed after re-bonding at room temperature.

[0278] Figure 2b The stress-strain data shown in were obtained from dumbbell film examples that had been cut and re-bonded according to the above protocol using a Hounsfield H10KS (200N load cell):

[0279] From the trend in the data, it can be speculated that using a higher annealing temperature (which is shown here as 40 °C) will further enhance the re-healing process of the films of the present invention. Observation of the self-healing properties of these films is expected to enable the healing of pinhole defects in elastomeric film products such as gloves and catheters; or in cavitated films such as elastomeric films used to bond active ingredients in lithium-ion batteries, and if left unhealed, would allow dendrite formation and battery short-circuiting.

[0280] Example 16: Shape memory property of the film of the present invention

[0281] Diligent observation also found that cast films produced from the latex of the present invention were able to exhibit shape memory behavior. To further demonstrate this observation, strips of the cast films of Examples 3 and 11 were immersed in hot (60 °C) water for 30 minutes (i.e., T > Tg (S) ), removed and immediately wrapped around a cylinder to form a coiled spring-like shape, and then cooled in cold (15 °C) water (i.e., T < Tg (S) ), as shown in Figure 3 (a) and (b). Note that the strip of the cast film of Example 11 had been decorated with an ink strip to assist in identification.

[0282] The thus formed samples were then placed in a water bath maintained at 60 °C for 1 minute, and they were observed to return to their near original shape (see Figure 3 (e)).

[0283] The process was repeated, but this time the samples were wrapped into a coil shape ( Figure 3 (c)) before cooling and allowed to relax. Additional experiments were conducted where the relaxed films were placed in a zigzag configuration ( Figure 3 (d)) using the same protocol and then relaxed at 60 °C.

[0284] Shape memory relaxation of the formed films prepared from Examples 3 and 11 was also evident when stored at room temperature, Figure 4 showing relaxation as a function of storage time for both folded and spring-like samples prepared according to the above temperature profile but then allowed to relax at 25 °C, the samples having first been warmed from storage at 15 °C for 1 minute after generating the shape.

Claims

1. An aqueous dispersion comprising core - shell polymer latex particles, wherein the shell of the core - shell polymer latex particles bears ethylenically unsaturated groups pendant from the polymer backbone of the shell of the latex particles, wherein the ethylenically unsaturated moiety is separated from the polymer backbone by at least 3 chemical bonds, and wherein the shell of the core - shell particles is cross - linked and the core of the core - shell particles is not cross - linked.

2. The aqueous dispersion according to claim 1, wherein the shell of the core - shell polymer latex particles comprises a structural unit represented by formula (1): – L – CR 1 =CR 2 R 3 (1) where L is a linear or branched divalent group providing at least two atoms in the chain between the polymer backbone of the shell of the latex particle and –CR 1 =CR 2 R 3 and is a divalent group which may be linear or branched and contains a cyclic group, and R 1 、R 2 and R 3 are independently selected from hydrogen and monovalent organic groups.

3. The aqueous dispersion according to claim 2, wherein the monovalent organic group is C 1 -C 4 alkyl group.

4. The aqueous dispersion according to claim 2, wherein –L– is selected from divalent hydrocarbon groups and groups containing at least one heteroatom in a chain connecting –CR 1 =CR 2 R 3 to the polymer backbone.

5. The aqueous dispersion according to claim 2, wherein –L– comprises a group selected from the following in a chain connecting –CR 1 =CR 2 R 3 to the polymer backbone: ester, ether, carbamate, thiocarbamate, urea, amide groups, and combinations thereof.

6. The aqueous dispersion according to any one of claims 1 or 2, wherein the core - shell polymer latex particles are produced by an aqueous emulsion polymerization comprising at least two steps, wherein: I) In the step of producing the core of the core - shell particles, an ethylenically unsaturated monomer that does not contain a monomer having a plurality of non - conjugated ethylenically unsaturated groups is polymerized; and II) In the step of producing the shell, a monomer mixture comprising the following is polymerized: a) monomers selected from conjugated dienes, monoethylenically unsaturated monomers that do not have a functional group capable of subsequently reacting after the formation of the latex particles to introduce an ethylenically unsaturated group, and combinations thereof; and bi) monomers having at least two non - conjugated ethylenically unsaturated groups that exhibit different reactivities in the aqueous emulsion polymerization, wherein at least a portion of the ethylenically unsaturated groups having lower reactivity remain unreacted after the termination of the aqueous emulsion polymerization; and / or bii) monoethylenically unsaturated monomers having a functional group capable of subsequently reacting after the formation of the latex particles to introduce an ethylenically unsaturated group; and c) monomers different from bi) having at least two non - conjugated ethylenically unsaturated groups, wherein: when monomer bi) is not present, at least a portion of the functional groups of monomer bii) react after the termination of the aqueous emulsion polymerization to introduce an ethylenically unsaturated group.

7. The aqueous dispersion according to claim 6, wherein: - monomers a) are selected from conjugated dienes, aromatic vinyl compounds, alkyl esters of ethylenically unsaturated acids, amides of ethylenically unsaturated acids, ethylenically unsaturated nitriles, vinyl esters of carboxylic acids, vinyl ethers, ethylenically unsaturated silanes, olefins, and any combination thereof; and / or - monomers bi) are selected from allyl (meth)acrylate and allyl crotonate; and / or - monomers bii) are selected from ethylenically unsaturated carboxylic acids, epoxy - functional ethylenically unsaturated compounds, hydroxy - functional ethylenically unsaturated compounds, amino - functional ethylenically unsaturated compounds, and any combination thereof; and / or - monomers c) are selected from monomers containing two ethylenically unsaturated groups; monomers containing three ethylenically unsaturated groups; monomers containing four ethylenically unsaturated groups, and any combination thereof; and - the monomers used in step I) are selected from monomers a) and bii) and combinations thereof.

8. The aqueous dispersion according to claim 7, wherein the monomer containing two ethylenically unsaturated groups is selected from divinylbenzene, ethylene glycol di(meth)acrylate or butanediol di(meth)acrylate; and / or the monomer containing three ethylenically unsaturated groups is selected from diallyl maleate or trimethylolpropane tri(meth)acrylate; and / or the monomer containing four ethylenically unsaturated groups is selected from pentaerythritol tetra(meth)acrylate.

9. The aqueous dispersion according to claim 7, wherein: - the conjugated diene is selected from 1,3 - butadiene, isoprene and 2,3 - dimethyl - 1,3 - butadiene; and / or - the aromatic vinyl compound is selected from styrene, α - methylstyrene, p - methylstyrene, tert - butylstyrene and vinyltoluene; and / or - the alkyl ester of the ethylenically unsaturated acid is selected from the n - alkyl ester, iso - alkyl ester or tert - alkyl ester of (meth)acrylic acid, wherein the alkyl has 1 - 20 carbon atoms, the reaction product of (meth)acrylic acid and glycidyl ester of a new carboxylic acid, and the (meth)acrylic acid alkoxyalkyl ester monomer; and / or - the amide of the ethylenically unsaturated acid is selected from (meth)acrylamide, N - hydroxymethyl(meth)acrylamide and diacetone acrylamide; and / or - the ethylenically unsaturated nitrile is selected from (meth)acrylonitrile and fumaric nitrile; and / or - the vinyl ester of the carboxylic acid is selected from vinyl acetate, vinyl propionate, vinyl butyrate, vinyl benzoate, vinyl 2 - ethylhexanoate, vinyl stearate and vinyl versatate; and / or - the ethylenically unsaturated silane is selected from trimethoxyvinylsilane, triethoxyvinylsilane, (meth)acrylic acid trimethylsilyl ester and (meth)acrylic acid triethylsilyl ester, 3 - (trimethoxysilyl)propyl (meth)acrylate; and / or the vinyl ether is selected from alkyl vinyl ether; and / or - the olefin is selected from ethylene, propylene, butene, hexene and cyclohexene; and / or - the ethylenically unsaturated carboxylic acid is selected from monofunctional acids, and / or difunctional acids and their half - esters; and / or - the hydroxy - functional ethylenically unsaturated compound is selected from 2 - hydroxyethyl (meth)acrylate, 2 - hydroxypropyl (meth)acrylate and 2 - hydroxybutyl (meth)acrylate; and / or - the amino - functional ethylenically unsaturated compound is selected from 2 - aminoethyl (meth)acrylate, 2 - aminopropyl (meth)acrylate and 2 - aminobutyl (meth)acrylate; and / or - The epoxy-functional ethylenically unsaturated compounds are selected from glycidyl (meth)acrylate, allyl glycidyl ether, vinyl glycidyl ether, vinylcyclohexene oxide, limonene oxide, 2-ethylglycidyl acrylate, 2-ethylglycidyl methacrylate, 2-(n-propyl)glycidyl acrylate, 2-(n-propyl)glycidyl methacrylate, 2-(n-butyl)glycidyl acrylate, 2-(n-butyl)glycidyl methacrylate, glycidyl methyl methacrylate, (3',4'-epoxyheptyl)-2-ethyl acrylate, (3',4'-epoxyheptyl)-2-ethyl methacrylate, (6',7'-epoxyheptyl) acrylate, (6',7'-epoxyheptyl) methacrylate, allyl 3,4-epoxyheptyl ether, 6,7-epoxyheptyl allyl ether, vinyl 3,4-epoxyheptyl ether, 6,7-epoxyheptyl vinyl ether, o-vinylbenzyl glycidyl ether, m-vinylbenzyl glycidyl ether, p-vinylbenzyl glycidyl ether, α-methylglycidyl methacrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, and combinations thereof.

10. The aqueous dispersion according to claim 9, wherein the vinylcyclohexene oxide is 3-vinylcyclohexene oxide.

11. The aqueous dispersion according to claim 9, wherein the conjugated diene is 1,3-butadiene; and / or the aromatic vinyl compound is styrene; and / or the new carboxylic acid is selected from tertiary carboxylic acids; and / or the monofunctional acid is selected from (meth)acrylic acid, crotonic acid, 2-carboxyethyl acrylate, vinylacetic acid, vinyl lactic acid, vinylsulfonic acid, 3-aminopropylsulfonic acid; and / or the difunctional acid is selected from fumaric acid, itaconic acid, maleic acid.

12. The aqueous dispersion according to claim 11, wherein the tertiary carboxylic acid is selected from neodecanoic acid or pivalic acid.

13. The aqueous dispersion according to claim 6, wherein the shell of the core-shell particles is prepared as follows: - An aqueous emulsion polymerization of a mixture of ethylenically unsaturated monomers comprising monomer a), monomer bii), and monomer c) and optionally monomer bi), thereby forming polymer latex particles having a shell with a first functional group derived from monomer bii); and - Subsequently reacting the polymer latex particles having the first functional group with an ethylenically unsaturated compound that has a second functional group reactive with the first functional group in addition to an ethylenically unsaturated moiety.

14. The aqueous dispersion according to claim 13, wherein: A) monomer bii) comprises an ethylenically unsaturated carboxylic acid and the first functional group is a carboxyl group, and the ethylenically unsaturated compound having the second functional group is selected from epoxy-functional ethylenically unsaturated compounds; or B) monomer bii) comprises an epoxy-functional ethylenically unsaturated compound and the first functional group is an epoxy group, and the ethylenically unsaturated compound having the second functional group is selected from ethylenically unsaturated carboxylic acids; or C) Monomer bii) an ethylenically unsaturated compound containing hydroxyl and / or amino functional groups, which gives rise to a first functional group selected from hydroxyl and amino, and said ethylenically unsaturated compound having a second functional group is selected from ethylenically unsaturated compounds having isocyanate or thiocyanate functional groups.

15. The aqueous dispersion according to claim 14, wherein the ethylenically unsaturated compound having epoxy functional groups in A) is as defined in claim 9; or the ethylenically unsaturated carboxylic acid in B) is as defined in claim 9.

16. The aqueous dispersion according to claim 6, wherein: - the core is constructed by seed latex, which is prefabricated or in-situ manufactured at the start of free radical emulsion polymerization, or - the core is formed by seeded free radical emulsion polymerization in the presence of prefabricated or in-situ manufactured seed latex; or - the core is formed in non-seeded free radical emulsion polymerization.

17. The aqueous dispersion according to claim 6, wherein the monomer mixture for polymerizing the core contains (meth)acrylic acid alkyl esters, and the monomer mixture for polymerizing the shell contains the following: - (meth)acrylic acid alkyl esters, - ethylenically unsaturated nitrile compounds, - ethylenically unsaturated acids, and - non-conjugated dienes; and the core-shell particles are reacted with an ethylenically unsaturated epoxide after termination of the aqueous emulsion polymerization.

18. The aqueous dispersion according to claim 17, wherein the monomer mixture for polymerizing the core contains n-butyl acrylate, and the (meth)acrylic acid alkyl ester in the monomer mixture for polymerizing the shell is n-butyl acrylate, and / or the ethylenically unsaturated nitrile compound is acrylonitrile, and / or the ethylenically unsaturated acid is methacrylic acid, and / or the non-conjugated diene is 1,4-butanediol diacrylate.

19. The aqueous dispersion according to claim 17, wherein the core-shell particles are reacted with glycidyl methacrylate after termination of the aqueous emulsion polymerization.

20. The aqueous dispersion according to any one of claims 1 or 2, wherein the core has a lower glass transition temperature Tg compared to the shell, which is measured by dynamic mechanical thermal analysis at a fixed frequency of 1 Hz and a heating rate of 3 °C / min.

21. The aqueous dispersion according to claim 20, wherein the Tg of the core is below 0 °C and the Tg of the shell is above 0 °C, which is measured by dynamic mechanical thermal analysis at a fixed frequency of 1 Hz and a heating rate of 3 °C / min.

22. The aqueous dispersion according to claim 20, wherein the Tg of the core is below -20 °C and the Tg of the shell is above 20 °C.

23. A method for manufacturing an aqueous dispersion containing core-shell polymer latex particles by aqueous emulsion polymerization as defined in any one of claims 6-19, wherein the shell of the core-shell polymer latex particles bears ethylenically unsaturated groups pendant from the polymer backbone of the shell of the latex particles, wherein the shell of the core-shell particles is crosslinked, and the core of the core-shell particles is not crosslinked.

24. An elastomeric film, which is made from the aqueous dispersion according to any one of claims 1 - 22.

25. The elastomeric film according to claim 24, wherein the film is self - supporting and has no sulfur cross - linking and no ionomer cross - linking.

26. The elastomeric film according to claim 24, wherein the elastomeric film has first and second outer surfaces and a core between the first and second outer surfaces, and the degree of cross - linking between polymer particles at the first and second outer surfaces is higher than the degree of cross - linking in the core of the film.

27. An article comprising the elastomeric film according to any one of claims 24 - 26.

28. The article according to claim 27, which is selected from disposable gloves, industrial gloves, household gloves, fabric - supported gloves, medical devices, or the article comprises a binder for an active ingredient of an energy battery.

29. The article according to claim 27, which is a surgical glove.

30. The article according to claim 27, which is an examination glove.

31. The article according to claim 28, which is selected from catheters and condoms.

32. The article according to claim 28, which is a female condom.

33. The article according to claim 28, wherein the energy battery is a lithium - ion storage battery.

34. A method for manufacturing a self - supporting elastomeric film, which comprises: a) providing a composition comprising the aqueous dispersion according to any one of claims 1 - 22, b) applying the composition onto a substrate to form a wet film, c) drying and / or curing the wet film to form an elastomeric film, and d) separating the elastomeric film from the substrate, e) optionally, before or after step d), heat - treating the elastomeric film at a temperature of 20°C - 160°C.

35. The method according to claim 34, wherein before or after step d), the elastomeric film is heat - treated at a temperature of 25°C - 100°C.

36. The method according to claim 34, wherein before or after step d), the elastomeric film is heat - treated at a temperature of 50°C - 100°C.

37. The method according to claim 34, wherein before or after step d), the elastomeric film is heat - treated at a temperature of 75°C - 100°C.

38. The method according to claim 34, wherein providing step a) neither includes adding sulfur and a promoter for sulfur vulcanization to the composition nor includes adding a zinc compound to the composition.

39. The method according to claim 38, wherein the composition in step a) has a pH of at most 8.

40. The method according to claim 38, wherein the composition in step a) has a pH of at most 7.

41. The method according to claim 34, wherein applying step b) includes casting, dip - molding, spraying, or knife - coating.

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