Water-based polymer, its production method, and its use

Abstract

The present invention relates to an aqueous multi-stage polymer, a method for preparing the same, and an aqueous multi-stage polymer emulsion containing the aqueous multi-stage polymer, which are suitable for printing ink applications. The emulsion containing the aqueous multi-stage polymer has demonstrated excellent gloss and anti-blocking performance.

Description

[Technical field]

[0001] The present invention relates to water-borne multi-stage polymers, their preparation methods, aqueous multi-stage polymer emulsions containing the aqueous multi-stage polymers, and their uses. In particular, the present invention relates to multi-stage polymer emulsions suitable for printing ink applications. [Background technology]

[0002] Aqueous polymer emulsions are applied in many fields such as coatings, adhesion, etc. When applied to inks, especially printing inks for food packaging, it is desirable for the material to have good gloss and blocking resistance. Many technical solutions have been proposed to develop emulsion polymers and / or compositions that can have such properties.

[0003] US Patent No. 8,420,709 B2 discloses a coating composition comprising at least one photoinitiator and at least one (meth)acrylic polymer having units derived from a (meth)acrylic monomer having at least one double bond and 8 to 40 carbon atoms in the alkyl residue. According to this disclosure, the coating composition exhibits high chemical resistance and increased weathering stability, as well as high blocking resistance and quickly becomes tack-free and dust-free. Moreover, the coating composition also results in a coating with high gloss. However, to obtain such a coating composition, special monomers are applied in addition to expensive exposure equipment.

[0004] French Patent No. 2819515A1 discloses a latex with a high dry extractive content and low Tg, obtained by emulsion copolymerization of styrene with 2-ethylhexyl acrylate, using as the sole emulsifier a styrene / maleic anhydride copolymer in the form of an aqueous solution and in partially or completely neutralized or esterified form. The object of the invention is to provide a latex with a dry extractive content of at least 40% by weight, a glass transition temperature (Tg) of less than or equal to 50°C and a Brookfield viscosity at 23°C of less than or equal to 1000 mPa·s. The invention also mentions that such a latex may be useful for use in paints, inks and varnishes, paper, etc. However, there is no information on properties such as gloss and blocking resistance. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] U.S. Patent No. 8420709B2 [Patent Document 2] French Patent No. 2819515A1 Summary of the Invention [Problem to be solved by the invention]

[0006] Therefore, there remains a need to develop more suitable emulsion systems for applications in printing inks requiring excellent gloss and blocking resistance properties, particularly printing inks for food packaging. [Means for solving the problem]

[0007] One object of the present invention is to provide an aqueous multi-stage polymer.

[0008] Another object of the present invention is to provide an aqueous multi-stage polymer emulsion comprising an aqueous multi-stage polymer, which when applied in a printing ink composition exhibits excellent gloss and blocking resistance.

[0009] A third object of the present invention is to provide a method for preparing an aqueous multi-stage polymer which is synthesized using monoethylenically unsaturated monomers in the presence of a styrene-maleic anhydride copolymer by multi-stage emulsion polymerization.

[0010] A fourth object of the present invention is to provide a use of the aqueous multi-stage polymer emulsion as a printing ink, particularly as a printing ink for food packaging. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Unless otherwise defined, all terms / terminology / nomenclature used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0012] The words "a," "an," and "the," when used in the foreign language specification of this application, when used to define a term, include both the plural and the singular form of that term.

[0013] As used herein, the term "polymer" in the singular or plural form includes both one or more homopolymers, i.e., polymers prepared from a single reactive monomeric compound, and one or more copolymers, i.e., polymers prepared by the reaction of at least two polymer-forming reactive monomeric compounds.

[0014] The term "multi-stage emulsion polymer" means a polymer that comprises at least a first stage polymer formed in a first emulsion polymerization process and that comprises at least a second stage polymer that is subsequently polymerized in a second emulsion polymerization process.

[0015] The designation (meth)acrylate and similar designations are used herein as shorthand for "acrylate and / or methacrylate."

[0016] All percentages and ratios are by weight unless otherwise stated.

[0017] The present invention relates to an aqueous multi-stage polymer emulsion comprising an aqueous multi-stage polymer which exhibits excellent gloss and blocking resistance, the aqueous multi-stage polymer being synthesized using monoethylenically unsaturated monomers in the presence of a styrene-maleic anhydride copolymer.

[0018] In one embodiment, the Fox Tg of the multi-stage polymers according to the present invention is in the range of 0 to 80° C. In the context of this application, the term Fox Tg refers to the glass transition temperature (Tg) calculated according to the following Fox equation, as disclosed in T. G. Fox, Bulletin of the American Physical Society, Volume 1, Issue No. 3, page 123 (1956): 1 / Tg=W 1 / Tg 1 +W 2 / Tg 2 +···+W n / Tg n During the ceremony, W 1 , W 2 , ... W n are the mass fractions of monomers 1, 2, ..., n, respectively, Tg 1 , Tg 2 , ...Tg n are the glass transition temperatures (in Kelvin) of the homopolymers of monomers 1, 2, ...n, respectively.

[0019] Tg values ​​for homopolymers of most monomers are known and are listed, for example, in Ullmann's Ecyclopedia of Industrial Chemistry, Vol. 5, Vol. A21, page 169, VCH Weinheim, 1992. Other sources of glass transition temperatures of homopolymers include, for example, J. Brandrup, EH Immergut, Polymer Handbook, 1st Edition, J. Wiley, New York 1966, 2nd Edition, J. Wiley, New York 1975 and 3rd Edition, J. Wiley, New York 1989.

[0020] For the avoidance of doubt, the Fox Tg is calculated without consideration of styrene-maleic anhydride copolymers.

[0021] The aqueous multistage polymer emulsion comprises one or more multistage polymers in an aqueous medium. There is no particular limitation on the monomers used to prepare the aqueous multistage polymer. In a preferred embodiment, the Fox Tg of the resulting polymer is in the range of 0 to 80°C, preferably 5 to 70°C, and most preferably 10 to 50°C. Meanwhile, the aqueous multistage polymer emulsion is preferably synthesized in at least three stages.

[0022] The monomers for the first stage polymer, the second stage polymer, and the third stage polymer may each be independently selected from monomers known to be useful in preparing water-based polymers in the printing ink art. These types of monomers may be the same or different, so long as the resulting polymer may have a particular Fox Tg as described above.

[0023] The monomers for the first stage polymer, the second stage polymer, and the third stage polymer may each independently comprise at least one hydrophobic monoethylenically unsaturated monomer (a).

[0024] The at least one hydrophobic monoethylenically unsaturated monomer (a) may be selected from the group consisting of (meth)acrylate monomers, (meth)acrylonitrile monomers, styrene monomers, vinyl alkanoate monomers, and monoethylenically unsaturated di- and tricarboxylic acid ester monomers.

[0025] In particular, the (meth)acrylate monomer is C 1 ~C 19 The alkyl (meth)acrylate may be, for example, but is not limited to, methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, n-octyl (meth)acrylate, n-decyl (meth)acrylate, n-dodecyl (meth)acrylate (i.e., lauryl (meth)acrylate), tetradecyl (meth)acrylate, oleyl (meth)acrylate, palmityl (meth)acrylate, stearyl (meth)acrylate, isobornyl (meth)acrylate, benzyl (meth)acrylate, phenyl (meth)acrylate, and mixtures thereof.

[0026] In particular, the styrene monomer is unsubstituted styrene or C 1 ~C 6 The alkyl substituted styrene may be, for example, but is not limited to, styrene, α-methylstyrene, ortho-, meta-, and para-methylstyrene, ortho-, meta-, and para-ethylstyrene, o,p-dimethylstyrene, o,p-diethylstyrene, isopropylstyrene, o-methyl-p-isopropylstyrene, or any mixture thereof.

[0027] In particular, the vinyl alkanoate monomer is C 2 ~C 11 It can be, but is not limited to, a vinyl ester of an alkanoic acid, such as vinyl acetate, vinyl propionate, vinyl butanoate, vinyl valerate, vinyl hexanoate, vinyl versatate, or mixtures thereof.

[0028] Additionally, the monoethylenically unsaturated di- and tricarboxylic acid ester monomers can be complete esters of monoethylenically unsaturated di- and tricarboxylic acids, such as, but not limited to, diethyl maleate, dimethyl fumarate, ethyl methyl itaconate, or any mixtures thereof.

[0029] In a preferred embodiment according to the present invention, one or more C 1 ~C 12 An alkyl (meth)acrylate, such as methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate, styrene, or a mixture thereof, is selected as the at least one hydrophobic monoethylenically unsaturated monomer (a).

[0030] For the synthesis of aqueous multistage polymers, it is possible that one or more hydrophilic monoethylenically unsaturated monomers (b) may be present.

[0031] Such hydrophilic monoethylenically unsaturated monomer (b) may be a monoethylenically unsaturated monomer containing at least one functional group selected from the group consisting of a carboxyl group, a carboxylic anhydride group, a sulfonic acid group, a phosphoric acid group, a hydroxyl group, and an amide group.

[0032] In particular, hydrophilic monoethylenically unsaturated monomers (b) include, but are not limited to, monoethylenically unsaturated carboxylic acids such as (meth)acrylic acid, itaconic acid, fumaric acid, citraconic acid, sorbic acid, cinnamic acid, glutaconic acid, and maleic acid; monoethylenically unsaturated carboxylic acid anhydrides such as itaconic anhydride, fumaric anhydride, citraconic anhydride, sorbic anhydride, cinnamic anhydride, glutaconic anhydride, and maleic anhydride; monoethylenically unsaturated amides, particularly N-alkylolamides such as (meth)acrylamide, N-methylol(meth)acrylamide, 2-hydroxyethyl(meth)acrylamide; and hydroxyalkyl esters of monoethylenically unsaturated carboxylic acids such as hydroxyethyl(meth)acrylate and hydroxypropyl(meth)acrylate.

[0033] In a preferred embodiment according to the present invention, acrylic acid, methacrylic acid, itaconic acid, acrylamide, methacrylamide or mixtures thereof are preferred as the at least one hydrophilic monoethylenically unsaturated monomer (b).

[0034] When both at least one hydrophobic monoethylenically unsaturated monomer (a) and at least one hydrophilic monoethylenically unsaturated monomer (b) are present, the at least one hydrophobic monoethylenically unsaturated monomer (a) may be present in an amount of at least 80% by weight, preferably at least 85% by weight, more preferably at least 90% by weight, and most preferably at least 95% by weight, while the at least one hydrophilic monoethylenically unsaturated monomer (b) may be present in an amount of at least 0.1% by weight and not more than 20% by weight, preferably not more than 15% by weight, more preferably not more than 10% by weight, and most preferably not more than 5% by weight. The above weight percentages are relative to the total weight of (a) and (b).

[0035] The monomers for the aqueous multi-stage polymer may further comprise one or more cross-linking monomers (c). The cross-linking monomers may be selected from di- or polyisocyanates, polyaziridines, polycarbodiimides, polyoxazolines, glyoxals, triols, epoxy molecules, organosilanes, carbamates, di- and triamines, hydrazides, carbodiimides, and multi-ethylenically unsaturated monomers. In the present invention, suitable crosslinking monomers include, but are not limited to, glycidyl (meth)acrylate, N-methylol (meth)acrylamide, (isobutoxymethyl)acrylamide, vinyltrialkoxysilanes, such as vinyltrimethoxysilane; alkylvinyldialkoxysilanes, such as dimethoxymethylvinylsilane; (meth)acryloxyalkyltrialkoxysilanes, such as (meth)acryloxyethyltrimethoxysilane, (3-acryloxypropyl)trimethoxysilane, and (3-methacryloxypropyl)trimethoxysilane, allyl methacrylate, diallyl phthalate, 1,4-butylene glycol dimethacrylate, 1,2-ethylene glycol dimethacrylate, 1,6-hexanediol diacrylate, divinylbenzene, or any mixture thereof.

[0036] The crosslinking agent may be added in an amount of 10% by weight or less, preferably 8% by weight or less, and more preferably 5% by weight or less, based on the total weight of all monomers used in the synthesis of the polymer.

[0037] The calculated Fox Tg of a polymer can be controlled by varying the mass ratio of hard and soft monomers applied in the synthesis of the polymer. In the present invention, a monomer is considered as a hard monomer if it can result in a homopolymer with a calculated Fox Tg of more than 10° C., otherwise it is considered as a soft monomer.

[0038] The soft monomer may include, but is not limited to, methyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, nonyl acrylate, ethyl acrylate, decyl methacrylate, isodecyl methacrylate, hexyl (meth)acrylate, cyclohexyl acrylate, dodecyl (meth)acrylate, octyl methacrylate, propyl acrylate, ethylene adipate, diethyl fumarate, 1,4-butadiene, 1-pentenylene, di-2-ethylhexyl maleate, di-2-ethylhexyl fumarate, and mixtures thereof. In a preferred embodiment, alkyl acrylates having 4 to 12 carbon atoms in the alkyl group, such as n-butyl acrylate and 2-ethylhexyl acrylate, are used as the soft monomer.

[0039] Hard monomers include methyl methacrylate, t-butyl acrylate, benzyl methacrylate, ethyl methacrylate, acrylamide, acrylic acid, methacrylic acid, itaconic acid, fumaric acid, citraconic acid, sorbic acid, cinnamic acid, glutaconic acid, and vinyl alcohol maleate, vinyl acetate, vinyl butyrate, vinyl formate, vinyl valerate, vinyl versitate, styrene, C 1 ~C 6 These may include, but are not limited to, alkyl substituted styrenes. In a preferred embodiment, acrylic acid, methacrylic acid, methyl (meth)acrylate, styrene, acrylamide, methacrylamide, or mixtures thereof are used as hard monomers.

[0040] In a preferred embodiment, the Fox Tg of the aqueous multistage polymer of the present invention is in the range of 0-80°C, preferably 5-70°C, and most preferably 10-50°C.

[0041] In one embodiment, the styrene-maleic anhydride (SMA) copolymer used in the present invention may have a weight average molecular weight of 500 to 15,000, a molar ratio of styrene / maleic anhydride of 1:6 to 6:1, and an acid index of 50 to 500 KOH / g. Preferably, the SMA may have a weight average molecular weight of 1,000 to 10,000, a molar ratio of styrene / maleic anhydride of 1:3 to 3:1, and an acid index of 100 to 500 KOH / g. More preferably, the SMA may have a weight average molecular weight of 1,500 to 7,500, a molar ratio of styrene / maleic anhydride of 1:3 to 3:1, and an acid index of 150 to 500 KOH / g. The SMA is used in the form of an aqueous solution, especially in neutralized form, and the neutralizing agent may be an organic base, such as an amine or ammonia, or an inorganic base, such as sodium hydroxide, potassium hydroxide, etc.

[0042] Examples of aqueous solutions of SMA copolymers that can be used in the present invention include aqueous solutions of hydrolyzed forms of styrene-maleic anhydride copolymers neutralized with sodium or ammonium salts. More specifically, many commercially available SMAs can be used for the purposes of the present invention. Such commercially available SMAs include, but are not limited to, products from Cray Valley, such as SMA® 1000, SMA® 2000, SMA® 3000, SMA® 3840, SMA® 4000, SMA® 1000 HNa, SMA® 2000 HNa, SMA® 3000 HNa, SMA® 1000G, SMA® 2000G, SMA® 3000G, etc.; products from Polyscope, such as XIRAN® SL series, XIRAN® SG series.

[0043] According to a preferred embodiment of the present invention, the SMA (dry weight) may comprise from 20% to 80% by weight, preferably from 30% to 70% by weight, and more preferably from 35% to 55% by weight, based on the total dry weight of the aqueous multistage polymer emulsion.

[0044] In a preferred embodiment, the first stage polymer may comprise 5% to 40% by weight, the second stage polymer may comprise 5% to 40% by weight, and the third stage polymer may comprise 25% to 90% by weight, based on the total weight of the multi-stage polymer (not including SMA). Preferably, the first stage polymer may comprise 10% to 30% by weight, the second stage polymer may comprise 10% to 30% by weight, and the third stage polymer may comprise 30% to 80% by weight, based on the total weight of the multi-stage polymer (not including SMA). More preferably, the first stage polymer may comprise 15% to 30% by weight, the second stage polymer may comprise 15% to 30% by weight, and the third stage polymer may comprise 40% to 70% by weight, based on the total weight of the multi-stage polymer (not including SMA).

[0045] In a preferred embodiment, the first stage polymer is 1 ~C 12 It is synthesized using alkyl (meth)acrylate and styrene, and C 1 ~C 12 The mass ratio of alkyl (meth)acrylate to styrene is greater than 1 (i.e., styrene is C 1 ~C 12 (Accounting for less than 50% by mass based on the total mass of alkyl (meth)acrylate and styrene).

[0046] In a more preferred embodiment, both the first stage polymer and the second stage polymer are 1 ~C 12 It is synthesized using alkyl (meth)acrylate and styrene. 1 ~C 12 The weight ratio of alkyl (meth)acrylate to styrene is greater than 1 for the first stage polymer and is C 1 ~C 12 The weight ratio of alkyl (meth)acrylate to styrene is less than 1.2 for the second stage polymer.

[0047] In another preferred embodiment, the first stage polymer, the second stage polymer, and the third stage polymer are 1 ~C 12They are synthesized using alkyl (meth)acrylates and styrene, and the styrene content increases (i.e., the mass ratio of styrene is lowest in the first stage polymer, higher in the second stage polymer, and highest in the third stage polymer).

[0048] In an even more preferred embodiment, C 1 ~C 12 The weight ratio of alkyl (meth)acrylate to styrene is greater than 1 for the first stage polymer and is C 1 ~C 12 The weight ratio of alkyl (meth)acrylate to styrene is less than 1.2 for the second stage polymer, and styrene is the only monomer used in the preparation of the third stage polymer.

[0049] The aqueous multi-stage polymer emulsion according to the present invention may be prepared by a multi-stage polymerization process including polymerization of a first stage monomer to give a first stage polymer, followed by polymerization of a second stage monomer to give a second stage polymer, and finally polymerization of a third stage monomer to give a third stage polymer. Multi-stage polymerization techniques well known in the art, such as those disclosed in US 2728804A, US 20170096575A1, US 20170355802A1, etc., may be used to prepare the aqueous multi-stage copolymer dispersion according to the present invention.

[0050] Emulsion polymerization may be carried out as a batch operation or in the form of a feed method (i.e., the monomer mixture is fed to the reactor in a stepwise or gradient procedure). The feed method is the preferred method. In such a method, the monomer mixture of the first stage polymerization is usually fed to the reactor by two or more spatially separated feed streams. After the feed is completed, the reaction is carried out for an additional 10 to 30 minutes, and optionally the mixture is subsequently fully or partially neutralized. After the first stage polymerization is finished, the monomer mixture of the second stage polymerization is fed to the reactor in the same manner as above. The monomers of the third stage polymerization are then added. After the feed is completed, the polymerization is maintained for an additional 30 to 90 minutes. The reaction mixture may then be subjected to an oxidizing agent, a neutralizing agent, etc.

[0051] In the multi-stage polymerization process, most surfactants known to those skilled in the art can be used. The surfactants used according to the present invention can be non-reactive surfactants, reactive surfactants, or a combination thereof. The surfactants can be blended together with the monomers and fed into the reactor. Alternatively, the surfactants can be added to the reaction medium first, followed by the monomers. The surfactants can be used in any suitable amount known to those skilled in the art, for example, a total amount of 0.1% to 6% by weight based on the total weight of the monomers.

[0052] Surfactant can be non-reactive anionic surfactant and / or non-ionic surfactant.Suitable non-reactive anionic surfactants include, but are not limited to, for example, alkyl, aryl, or alkylaryl sulfate, sulfonate, or phosphate; alkylsulfonic acid; sulfosuccinate; fatty alcohol ether sulfate and fatty acid.Suitable non-reactive non-ionic surfactants include, for example, alcohol or phenol ethoxylate, such as polyoxyethylene alkyl phenyl ether.

[0053] Surfactant can also be polymerizable surfactant, also called reactive surfactant, and contains at least one ethylenically unsaturated functional group.Suitable polymerizable surfactant includes but is not limited to, for example, allyl polyoxyalkylene ether sulfate, such as sodium salt of allyl polyoxyethylene alkyl ether sulfate, allyl alkyl succinic acid sulfonate, allyl ether hydroxyl propane sulfonate, such as sodium salt, polyoxyethylene styrenated phenyl ether sulfate, such as ammonium salt, such as DKS Hitenol® AR 1025 and DKS Hitenol® AR 2020, polyoxyethylene alkyl phenyl ether sulfate ammonium salt, polyoxyethylene allyloxy nonyl phenoxypropyl ether, and phosphoric acid acrylate, such as SIPOMER® PAM 100, phosphoric acid acrylate, such as SIPOMER® PAM 200, etc.

[0054] The emulsion polymerization can be carried out in the presence of a variety of common initiation systems, including but not limited to thermal or redox initiators. The initiator is typically used in an amount of 10% by weight or less, preferably 0.02 to 5% by weight, more preferably 0.1 to 1.5% by weight, based on the total weight of the second stage monomers.

[0055] Thermal initiators such as peroxides, persulfates, and azo compounds are commonly used.Peroxides that can be used include, but are not limited to, inorganic peroxides, such as hydrogen peroxide or peroxodisulfates, or organic peroxides, such as tert-butyl, p-menthyl, or cumyl hydroperoxide, tert-butyl perpivalate, and dialkyl or diaryl peroxides, such as di-tert-butyl or di-cumyl peroxide.Azo compounds that can be used include, but are not limited to, 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile). Among these, the thermal initiators preferably include sodium persulfate (SPS), potassium persulfate (KPS), ammonium persulfate (APS), 2,2'-azobis(amidinopropyl) dihydrochloride (AIBA, V-50 TM), and 4,4'-azobis(4-cyanovaleric acid) (ACVA, V501).

[0056] The redox initiator usually includes an oxidizing agent and a reducing agent. Suitable oxidizing agents include the above-mentioned peroxides. Suitable reducing agents can be alkali metal sulfites, such as potassium sulfite and / or sodium sulfite, or alkali metal bisulfites, such as potassium bisulfite and / or sodium bisulfite. A preferred redox initiator includes an oxidizing agent selected from the group consisting of t-butyl hydroperoxide and hydrogen peroxide, and a reducing agent selected from ascorbic acid, sodium formaldehyde sulfoxylate, sodium acetone bisulfite, and sodium metabisulfite (sodium disulfite).

[0057] The polymerization may be carried out and maintained at a temperature below 100° C. throughout the reaction. Preferably, the polymerization is carried out at a temperature between 60° C. and 95° C. Depending on the various polymerization conditions, the polymerization may be carried out for several hours, for example, 2 to 8 hours.

[0058] Organic and / or inorganic bases may be added to the polymerization system as neutralizing agents during polymerization or after completion of the polymerization process. Suitable neutralizing agents include, but are not limited to, inorganic bases such as ammonia, sodium hydroxide / potassium hydroxide, sodium carbonate / potassium carbonate, or any combination thereof. Organic bases such as dimethylamine, diethylamine, triethylamine, monoethanolamine, triethanolamine, or mixtures thereof may also be used as neutralizing agents. Among them, sodium hydroxide, ammonia, dimethylaminoethanol, 2-amino-2-methyl-1-propanol, or any mixture thereof are preferred as neutralizing agents useful in the polymerization process. Upon addition of the neutralizing agent, the pH of the final polymer emulsion will be in the range of 6.0 to 10.0, preferably in the range of 7.0 to 9.5, and more preferably in the range of 7.0 to 9.0.

[0059] The solids content of the aqueous multi-stage copolymer dispersion according to the present invention may be in the range of 10% to 70% by weight, preferably 20% to 60% by weight, more preferably 30 to 60% by weight, and most preferably 40 to 60% by weight.

[0060] The fourth object of the present invention is to provide a use of the aqueous multi-stage polymer emulsion as a printing ink, especially a printing ink for food packaging. In different ink applications, the component concentrations can be adjusted. For example, a gravure ink or a flexographic printing ink preferably contains about 8-60% by weight of the aqueous multi-stage polymer emulsion, about 3-30% by weight of a pigment colorant, and about 15-60% by weight of a solvent or water.

[0061] Colorants can be organic or inorganic. The most common pigments include azo dyes (e.g., Solvent Yellow 14, Disperse Yellow 23, and Metanil Yellow), anthraquinone dyes (e.g., Solvent Red 111, Disperse Violet 1, Solvent Blue 56, and Solvent Orange 3), xanthene dyes (Solvent Green 4, Acid Red 52, Basic Red 1, and Solvent Orange 63), azine dyes (e.g., Jet Black), and the like. The main organic pigments that can be used include Diarylide Yellow AAOT (e.g. Pigment Yellow 14 Cl#21095), Diarylide Yellow AAOA (e.g. Pigment Yellow 12 Cl#21090), Phthalocyanine Blue (e.g. Pigment Blue 15), Lithol Red (e.g. Pigment Red 52:1 C 5860:1), Toluidine Red (e.g. Pigment Red 22 Cl#12315), Dioxazine Violet (e.g. Pigment Violet 23 Cl#51319), Phthalocyanine Green (e.g. Pigment Green 7 Cl#74260), Phthalocyanine Blue (e.g. Pigment Blue 15 Cl#74160), Naphthoic Acid Red (e.g. Pigment Red 48:2 Cl#15865:2). Inorganic pigments include titanium dioxide (e.g., Pigment White 6 Cl#77891), carbon black (e.g., Pigment Black 7 Cl#77266), iron oxide (e.g., red, yellow, and brown), ferric oxide black (e.g., Pigment Black 1 1 Cl#77499), chromium oxide (e.g., green), ferric ammonium ferrocyanide (e.g., blue), etc. Colorants are not limited to the above.Thus, the colorant may be any conventional organic or inorganic pigment, for example zinc sulfide, Pigment White 6, Pigment Yellow 1, Pigment Yellow 3, Pigment Yellow 12, Pigment Yellow 13, Pigment Yellow 14, Pigment Yellow 17, Pigment Yellow 63, Pigment Yellow 65, Pigment Yellow 73, Pigment Yellow 74, Pigment Yellow 75, Pigment Yellow 83, Pigment Yellow 97, Pigment Yellow 98, Pigment Yellow 106, Pigment Yellow 1 14, Pigment Yellow 121, Pigment Yellow 126, Pigment Yellow 127, Pigment Yellow 136, Pigment Yellow 174, Pigment Yellow 176, Pigment Yellow 188, Pigment Orange 5, Pigment Orange 13, Pigment Orange 16, Pigment Orange 34, Pigment Red 2, Pigment Red 9, Pigment Red 14, Pigment Red 17, Pigment Red 22, Pigment Red 23, Pigment Red 37, Pigment Red 38, Pigment Red 41, Pigment Red 42, Pigment Red 57, Pigment Red 1 Pigment Red 12, Pigment Red 122, Pigment Red 170, Pigment Red 210, Pigment Red 238, Pigment Blue 15, Pigment Blue 15:1, Pigment Blue 15:2, Pigment Blue 15:3, Pigment Blue 15:4, Pigment Green 7, Pigment Green 36, Pigment Violet 19, Pigment Violet 23, Pigment Black 7, and the like.

[0062] Printing inks may also contain conventional ink additives to adjust the flow, surface tension, and gloss of the printing ink. Such additives are typically polymeric dispersants, surfactants, waxes, or combinations thereof. These additives may function as leveling agents, wetting agents, fillers, dispersants, defoamers, or degassing agents, or alternatively, additional auxiliaries may be added to provide specific functions. Laminated printing inks may contain polymeric dispersants, if the colorant is a pigment, to disperse the pigment during mixing and grinding operations in the solvent. All components of the ink may be blended together and ground to bring the pigment particles to the desired size distribution, typically 10 microns or less, or the pigment and polymeric dispersant may be premixed and ground in a solvent (medium) to form a "base", which is then blended with the remaining components of the ink composition. The ink components may be mixed in a high-speed mixer until a slurry consistency is reached, and then passed through a media mill until the pigment is 10 microns or less. Because of their versatility, the inks of the present invention can be prepared without polymeric dispersants, but are preferably prepared with polymeric dispersants, for example for grinding in polyvinyl butyral or for blending with, for example, nitrocellulose-based or acrylic resin solutions. Thus, the inks of the present invention may contain from 0 to about 12 parts by weight of polymeric dispersant. Other useful colorants, solvents, and adjuvants can be identified by consulting The Printing Ink Manual.

[0063] The printing ink preferably contains 8 to 60% by mass, preferably 15 to 50% by mass, of an aqueous multi-stage polymer emulsion, 3 to 30% by mass, preferably 6 to 30% by mass, of a pigment, 15 to 60% by mass, preferably 30 to 60% by mass, of water, and 0.1 to 5% by mass of additives, such as surfactants, defoamers, and waxes.

[0064] The present invention is further demonstrated and illustrated in the examples, but is not limited to the embodiments described therein. EXAMPLES

[0065] Description of commercially available materials used in the following examples: SMA® 1000, styrene-maleic anhydride copolymer (Mn approx. 2,000, styrene:maleic anhydride molar ratio approx. 1:1), manufactured by Cray Valley XIRAN® 1000, styrene-maleic anhydride copolymer (Mn ≈5,000, styrene:maleic anhydride molar ratio ≈1:1), manufactured by Polyscope Uniol D-1200, polypropylene glycol, NOF Corporation (hereinafter referred to as "PPG") EHA: 2-ethylhexyl acrylate, manufactured by Mitsubishi Chemical Corporation Styrene: GODO Corporation

[0066] All experiments described below were carried out at a temperature of 20° C. unless otherwise stated.

[0067] Example 1 (present invention): To a 2.5 L glass reactor equipped with a mechanical stirrer was added 7.93 g of PPG, 19.6 g of diethylene glycol monoethyl ether, 235.0 g of SMA® 1000, and 249.0 g of deionized water. The mixture was then diluted with 136.7 g of 25% NH 3 The mixture was neutralized with aqueous solution and 50.0 g of deionized water and stirred at 88°C for 60 minutes. The reaction temperature was maintained at 88°C until cooling. After the addition of 2.35 g of ammonium persulfate dissolved in 28.0 g of deionized water, a mixture containing 24.7 g of styrene and 45.8 g of EHA was added over 30 minutes and then stirred for an additional 10 minutes. Then, a mixture containing 39.4 g of styrene and 19.4 g of EHA was added over 20 minutes and stirred for an additional 10 minutes. Then, 2.4 g of ammonium persulfate and 25.0 g of deionized water were added and stirred for 5 minutes. Finally, 105.8 g of styrene was added over 40 minutes and stirred for an additional 90 minutes. After polymerization at the same temperature, the mixture was cooled. This emulsion was used for evaluation without further treatment.

[0068] The resulting polymer has a Fox Tg of 29° C. The resulting aqueous polymer emulsion has a pH of 9 and a solids content of 49% by weight.

[0069] Example 2 (present invention): To a 2.5 L glass reactor equipped with a mechanical stirrer was added 7.93 g of PPG, 19.6 g of diethylene glycol monoethyl ether, 188.0 g of SMA® 1000, and 275.7 g of deionized water. The mixture was then diluted with 109.4 g of 25% NH 3 The mixture was neutralized with an aqueous solution and 50.0 g of deionized water and stirred at 88°C for 60 minutes. The reaction temperature was maintained at 88°C until cooling. After the addition of 2.8 g of ammonium persulfate dissolved in 28.0 g of deionized water, a mixture containing 19.7 g of styrene and 36.7 g of EHA was added over 30 minutes and then stirred for an additional 10 minutes. After that, a mixture containing 47.2 g of styrene and 23.3 g of EHA was added over 20 minutes and stirred for an additional 10 minutes. Then, 2.5 g of ammonium persulfate and 25.0 g of deionized water were added and stirred for 5 minutes. Finally, 155.1 g of styrene was added over 40 minutes and stirred for an additional 90 minutes. After polymerization at the same temperature, the mixture was cooled. This emulsion was used for evaluation without further treatment.

[0070] The resulting polymer has a Fox Tg of 44° C. The resulting aqueous polymer emulsion has a pH of 9 and a solids content of 49% by weight.

[0071] Example 3 (present invention): To a 2.5 L glass reactor equipped with a mechanical stirrer was added 7.93 g of PPG, 19.6 g of diethylene glycol monoethyl ether, 164.5 g of XIRAN® 1000, and 288.9 g of deionized water. The mixture was then diluted with 95.7 g of 25% NH 3The mixture was neutralized with an aqueous solution and 50.0 g of deionized water and stirred at 88°C for 60 minutes. The reaction temperature was maintained at 88°C until cooling. After the addition of 3.1 g of ammonium persulfate dissolved in 28.0 g of deionized water, a mixture containing 6.4 g of styrene and 85.2 g of EHA was added over 30 minutes and then stirred for an additional 10 minutes. After that, a mixture containing 30.6 g of styrene and 30.6 g of EHA was added over 20 minutes and stirred for an additional 10 minutes. Then, 2.8 g of ammonium persulfate and 25.0 g of deionized water were added and stirred for 5 minutes. Finally, 152.8 g of styrene was added over 40 minutes and stirred for an additional 90 minutes. After polymerization at the same temperature, the mixture was cooled. This emulsion was used for evaluation without further treatment.

[0072] The resulting polymer has a Fox Tg of 10° C. The resulting aqueous polymer emulsion has a pH of 9 and a solids content of 49% by weight.

[0073] Example 4 (invention): To a 2.5 L glass reactor equipped with a mechanical stirrer was added 7.93 g of PPG, 19.6 g of diethylene glycol monoethyl ether, 188.0 g of XIRAN® 1000, and 275.7 g of deionized water. The mixture was then diluted with 109.4 g of 25% NH 3 The mixture was neutralized with an aqueous solution and 50.0 g of deionized water and stirred at 88°C for 60 minutes. The reaction temperature was maintained at 88°C until cooling. After the addition of 2.8 g of ammonium persulfate dissolved in 28.0 g of deionized water, a mixture containing 34.6 g of styrene and 64.2 g of EHA was added over 30 minutes and then stirred for an additional 10 minutes. After that, a mixture containing 47.2 g of styrene and 23.3 g of EHA was added over 20 minutes and stirred for an additional 10 minutes. Then, 2.5 g of ammonium persulfate and 25.0 g of deionized water were added and stirred for 5 minutes. Finally, 112.8 g of styrene was added over 40 minutes and stirred for an additional 90 minutes. After polymerization at the same temperature, the mixture was cooled. This emulsion was used for evaluation without further treatment.

[0074] The resulting polymer has a Fox Tg of 23° C. The resulting aqueous polymer emulsion has a pH of 9 and a solids content of 49% by weight.

[0075] Example 5 (invention): To a 2.5 L glass reactor equipped with a mechanical stirrer was added 7.93 g of PPG, 19.6 g of diethylene glycol monoethyl ether, 188.0 g of XIRAN® 1000, and 275.7 g of deionized water. The mixture was then diluted with 109.4 g of 25% NH 3 The mixture was neutralized with an aqueous solution and 50.0 g of deionized water and stirred at 88°C for 60 minutes. The reaction temperature was maintained at 88°C until cooling. After the addition of 2.8 g of ammonium persulfate dissolved in 28.0 g of deionized water, a mixture containing 5.9 g of styrene and 78.7 g of EHA was added over 30 minutes and then stirred for an additional 10 minutes. After that, a mixture containing 28.2 g of styrene and 28.2 g of EHA was added over 20 minutes and stirred for an additional 10 minutes. Then, 2.5 g of ammonium persulfate and 25.0 g of deionized water were added and stirred for 5 minutes. Finally, 141.0 g of styrene was added over 40 minutes and stirred for an additional 90 minutes. After polymerization at the same temperature, the mixture was cooled. This emulsion was used for evaluation without further treatment.

[0076] The resulting polymer has a Fox Tg of 10° C. The resulting aqueous polymer emulsion has a pH of 9 and a solids content of 49% by weight.

[0077] Example 6 (Comparative Example): A 2.5 L glass reactor equipped with a mechanical stirrer was charged with 135.8 g of XIRAN® 1000 and 506.3 g of deionized water. The mixture was then diluted with 78.2 g of 25% NH 3The mixture was neutralized with aqueous solution and 78.2 g of deionized water and heated at 85° C. The reaction temperature was maintained at 85° C. until cooled. After adding 7.4 g of ammonium persulfate dissolved in 82.3 g of deionized water, a mixture containing 267.6 g of styrene and 144.1 g of EHA was added over 120 minutes and stirred at the same temperature for 120 minutes. After polymerization, the mixture was cooled. This emulsion was used for evaluation without further treatment.

[0078] The resulting aqueous polymer emulsion has a pH of 8 and a solids content of 43% by weight.

[0079] Paint Preparation and Test Methods The emulsions prepared in Examples 1 to 6 were printed on paper using a bar coater No. 6 and dried in an oven at 110° C. for 1 minute.

[0080] Gloss Measurement a) Prepare a drawdown under the conditions described above. b) Allow the drawdown to dry at room temperature for 24 hours. c) Measure the gloss five times (at a 60° angle) and record the average gloss value. 5=Very high gloss 3=Intermediate level 1=Very low gloss

[0081] Blocking resistance measurement a) Prepare a drawdown under the conditions described above. b) Allow the drawdown to dry at room temperature for 24 hours. c) The drawdown is cut into 4 x 5 cm pieces, placed face to face, and then stored at 50°C and 80% relative humidity for 24 hours. 2 A load of was applied. d) After storage, release the pressure and allow the specimen to cool to room temperature. e) The drawdowns are pulled away from each other and the damage rated as follows: 5=No damage / completely detached 3=Lots of damage / blocking 1=Stay with me

[0082] The results of the gloss and blocking resistance measurements for Examples 1 to 6 are shown in Table 1 below.

[0083] [Table 1]

Claims

1. An aqueous multi-stage polymer, the aqueous multi-stage polymer being synthesized using monoethylenically unsaturated monomers in the presence of a styrene-maleic anhydride (SMA) copolymer.

2. 2. The aqueous multistage polymer of claim 1, having a Fox Tg in the range of 0 to 80°C, preferably 5 to 70°C, more preferably 10 to 50°C.

3. 3. The aqueous multistage polymer of claim 1 or 2, wherein said SMA copolymer has a weight average molecular weight (Mw) of 500 to 15,000, a styrene / maleic anhydride molar ratio of 1:6 to 6:1, and an acid index of 50 to 500 KOH / g, preferably said SMA copolymer has a Mw of 1,000 to 10,000, a styrene / maleic anhydride molar ratio of 1:3 to 3:1, and an acid index of 100 to 500 KOH / g, and more preferably said SMA copolymer has a Mw of 1,500 to 7,500, a styrene / maleic anhydride molar ratio of 1:3 to 3:1, and an acid index of 150 to 500 KOH / g.

4. The aqueous multi-stage polymer of claim 3 which is synthesized in at least three stages.

5. 5. The aqueous multistage polymer of claim 3 or 4, wherein the SMA (dry weight) comprises from 20% to 80% by weight, preferably from 30% to 70% by weight, more preferably from 35% to 55% by weight, based on the total dry weight of the multistage polymer.

6. 6. The aqueous multistage polymer of any one of claims 3 to 5, wherein the first stage polymer comprises 5% to 40% by weight, the second stage polymer comprises 5% to 40% by weight, and the third stage polymer comprises 25% to 90% by weight, based on the total weight of the multistage polymer (not including SMA); preferably, the first stage polymer comprises 10% to 30% by weight, the second stage polymer comprises 10% to 30% by weight, and the third stage polymer comprises 30% to 80% by weight; and more preferably, the first stage polymer comprises 15% to 30% by weight, the second stage polymer comprises 15% to 30% by weight, and the third stage polymer comprises 40% to 70% by weight.

7. The first stage polymer is １ ~C １２ It is synthesized using alkyl (meth)acrylate and styrene, and C １ ~C １２ 7. The aqueous multistage polymer of any one of claims 3 to 6, wherein the weight ratio of alkyl (meth)acrylate to styrene is greater than 1.

8. The second stage polymer is １ ~C １２ It is synthesized using alkyl (meth)acrylate and styrene, and C １ ~C １２ 8. The aqueous multistage polymer of any one of claims 7, wherein the weight ratio of alkyl (meth)acrylate to styrene is less than 1.2 for said second stage polymer.

9. The first stage polymer, the second stage polymer, and the third stage polymer are １ ~C １２ 7. The water-based multistage polymer of any one of claims 3 to 6, synthesized with an alkyl (meth)acrylate and styrene, with increasing weight ratios of styrene in said first stage polymer, said second stage polymer, and said third stage polymer.

10. 9. The aqueous multistage polymer of any one of claims 8 wherein styrene is the only monomer used in the preparation of the third stage polymer.

11. 11. An aqueous multistage polymer emulsion comprising the aqueous multistage polymer of any one of claims 1 to 10 in an aqueous medium.

12. 12. The aqueous multistage polymer emulsion of claim 11, wherein the solids content is in the range of 10% to 70%, preferably 20% to 60%, more preferably 30 to 60%, and most preferably 40 to 60% by weight.

13. A method for producing the multi-stage polymer of any one of claims 1 to 10, comprising the steps of: Step 1: polymerizing a first stage polymer in the presence of a styrene-maleic acid copolymer; Step 2: subsequently polymerizing the second stage polymer; and Step 3: Polymerizing the third stage polymer A method comprising:

14. 13. A printing ink comprising any of the multi-stage polymer emulsions of claims 11 or 12.

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