WO2022196396A1 - Aqueous resin dispersion, method for producing same, and ink containing said dispersion - Google Patents

Abstract

An aqueous resin dispersion which contains a urethan polymer A and an acrylic polymer B in each particle, wherein: the acrylic polymer B has a constituent unit derived from a radically polymerizable monomer that has an alicyclic skeleton; and the glass transition temperature of the acrylic polymer B is not less than -60°C but less than 5°C.

Description

Aqueous resin dispersion, method for producing the same, and ink containing the dispersion

The present invention relates to aqueous resin dispersions and inks containing said dispersions.
This application claims priority based on Japanese Patent Application No. 2021-042708 filed in Japan on March 16, 2021, the content of which is incorporated herein.

Aqueous resin dispersions for aqueous coating materials are widely used in various applications because they are excellent in mechanical properties and chemical resistance, and are easy to mold at low cost. Since these resins are excellent in recyclability, their applications are further expanding against the background of recent global environmental problems. However, it is generally considered difficult to adhere to a base material such as polypropylene, which is a base material having low surface tension and poor adhesion.
As an aqueous resin dispersion for aqueous coating materials, for example, Patent Document 1 discloses an acrylic/urethane block co-polymer having a pendant nonionic hydrophilic group and a pendant anionic hydrophilic group on the side chain of a urethane block that crosslinks an acrylic block. A method using an aqueous polymer emulsion is described. Patent Document 2 describes a method of using an acrylic/urethane composite resin emulsion in which an ethylenically unsaturated monomer is reacted with a urethane urea resin containing mercapto groups at both ends.

Although the method described in Patent Document 1 has good film formability, a pendant nonionic hydrophilic group and a pendant anionic hydrophilic group are introduced into the side chain of the urethane block in order to impart film formability. Therefore, there is a problem that it is difficult to impart adhesion to low-surface-tension, difficult-to-adhere substrates such as polypropylene substrates.

In addition, although the method described in Patent Document 2 has excellent ink pigment dispersibility and adhesion to non-polar film substrates, it has an acidic group in the acrylic block, so it is a low-molecular-weight polymer that is widely used as a diluent solvent for water-based inks and the like. It has a problem that it is thickened by alcohol and has poor applicability as a water-based ink.

JP 2009-057451 A JP 2017-002222 A

An object of the present invention is to provide a water-based resin dispersion which, when used as a raw material for a water-based ink, provides a coating film having low viscosity, excellent coating properties, adhesion to various plastic film substrates, and good gloss, and the above-mentioned An object of the present invention is to provide an ink containing a dispersion.

That is, the gist of the present invention is the following [1] to [32].
[1] The acrylic polymer B contains a urethane polymer A and an acrylic polymer B in the same particle, the acrylic polymer B having a constitutional unit derived from a radically polymerizable monomer having an alicyclic skeleton, and the acrylic polymer B An aqueous resin dispersion having a glass transition temperature of -60°C or higher and lower than 5°C.
[2] The acrylic polymer B has a structural unit derived from a radically polymerizable monomer having an alicyclic skeleton in an amount of 5% by mass or more relative to the total mass of the structural units constituting the acrylic polymer B, [ 1] The aqueous resin dispersion described above.
[3] The aqueous resin dispersion according to [1] or [2], wherein the acrylic polymer B has a glass transition temperature of -40°C or higher and -2°C or lower.
[4] The aqueous resin dispersion according to any one of [1] to [3], wherein the acrylic polymer B has a glass transition temperature of -40°C or higher and -6°C or lower.
[5] The aqueous resin dispersion according to any one of [1] to [4], wherein the hydrodynamic average particle size of the aqueous resin dispersion measured by a dynamic light scattering method is 120 nm or less.
[6] The aqueous resin dispersion according to any one of [1] to [5], wherein the solid content of the aqueous resin dispersion is 35% by mass or more with respect to the total mass of the aqueous resin dispersion.
[7] The acrylic polymer B contains 5% by mass or more and 95% by mass of structural units derived from a radically polymerizable monomer having an alicyclic skeleton, based on the total mass of the structural units constituting the acrylic polymer B. It preferably has the following, more preferably 10% by mass or more and 90% by mass or less, even more preferably 30% by mass or more and 85% by mass or less, the aqueous according to any one of [1] to [6] Resin dispersion.
[8] The radically polymerizable monomer in which the acrylic polymer B has an alicyclic skeleton is cyclohexyl (meth)acrylate, 3,4-epoxycyclohexyl (meth)acrylate, isobornyl (meth)acrylate and 4-t- It is preferably at least one selected from the group consisting of butylcyclohexyl (meth)acrylate, more preferably at least one selected from the group consisting of cyclohexyl (meth)acrylate and isobornyl (meth)acrylate. ] The aqueous resin dispersion according to any one of [7].
[9] The acrylic polymer B contains a structural unit derived from another vinyl-based monomer d copolymerizable with a radically polymerizable monomer having an alicyclic skeleton, and the other vinyl-based monomer Any one of [1] to [8], wherein the content of the structural unit derived from d is more preferably 10% by mass or more and 90% by mass or less, and further preferably 25% by mass or more and 70% by mass or less. The aqueous resin dispersion according to .
[10] The other vinyl-based monomer d is an alkyl (meth)acrylate, hydroxyalkyl (meth)acrylate, glycol di(meth)acrylate, or alkylamino (meth)acrylate in which the alkyl group has 1 to 18 carbon atoms. , a monomer having an acid group, dimethylaminoethyl (meth)acrylate methyl chloride salt, allyl (meth)acrylate, trimethylolpropane tri(meth)acrylate, glycidyl (meth)acrylate, styrene, vinyl acetate, vinyl propionate, and (meth) is preferably at least one selected from the group consisting of acrylonitrile; methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, t -More preferably at least one selected from the group consisting of butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, and stearyl (meth)acrylate; methyl (meth)acrylate, At least one selected from the group consisting of ethyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, t-butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate is more preferable, the aqueous resin dispersion according to any one of [1] to [9].
[11] Any one of [1] to [10], wherein the average particle size of the urethane polymer A measured by photon correlation spectroscopy is preferably 30 to 100 nm, more preferably 40 to 80 nm. The aqueous resin dispersion according to item 1.
[12] Any one of [1] to [11], wherein the viscosity of the urethane polymer A at 20° C. measured according to DIN53019 is preferably 10 to 50 mPa s, more preferably 20 to 40 mPa s. The aqueous resin dispersion according to the item.
[13] The content of the acrylic polymer B with respect to the total mass of the urethane polymer A and the acrylic polymer B is preferably 10 to 80% by mass, more preferably 20 to 50% by mass. 12], the aqueous resin dispersion according to any one of items.
[14] The content of the acrylic polymer B with respect to the total mass of the urethane polymer A and the acrylic polymer B is preferably 20 to 90% by mass, more preferably 50 to 80% by mass. 13], the aqueous resin dispersion according to any one of items.
[15] The solid content of the aqueous resin dispersion is preferably 30% by mass or more and 60% by mass or less, more preferably 35% by mass or more and 50% by mass or less, relative to the total mass of the aqueous resin dispersion. The preferred aqueous resin dispersion according to any one of [1] to [14].
[16] The hydrodynamic average particle size of the aqueous resin dispersion measured by a dynamic light scattering method is preferably 30 to 150 nm, more preferably 40 to 100 nm, [1] to [15] ] The aqueous resin dispersion as described in any one of ].
[17] An ink containing the water-based resin dispersion is prepared, and the viscosity of the ink at 23° C. is measured using a Zahn Cup No. 3 (manufactured by Tester Sangyo Co., Ltd.), the Zahn cup passage time is preferably less than 10 seconds, more preferably less than 10 seconds and 3 seconds or more, and 9.5 seconds or less and 5.0 seconds or more. is more preferable, the aqueous resin dispersion according to any one of [1] to [16].
[18] An ink containing the water-based resin dispersion is prepared, the ink is printed on a resin film to form an ink coating film, dried under drying conditions at 25 ° C. for 1 day, and the thickness after drying is 1. The glossiness (60°) when the ink film was formed to a thickness of 2 μm was measured using a variable angle gloss meter (manufactured by Nippon Denshoku Industries Co., Ltd., trade name: GLOSS METER VG7000), and the gloss value was 10. The aqueous resin dispersion according to any one of [1] to [17], which is preferably 5 or more and 20.0 or less, more preferably 9.0 or more and 18.0 or less.
[19] An ink containing the water-based resin dispersion is prepared, the ink is printed on a resin film to form an ink coating film, dried under drying conditions at 25 ° C. for 1 day, and the thickness after drying is 1. An ink film of ~2 μm was applied, cellophane tape (manufactured by Nichiban Co., Ltd., trade name: CT405AP-12) was attached, and a peel test was performed in the vertical direction to measure the adhesion to the substrate. It is preferably 15 area% or more and 100 area% or less, more preferably 20 area% or 100 area% or less, further preferably 30 area% or 99 area% or less, [1] to [18] The aqueous resin dispersion according to any one of the items.
[20] The SP value calculated from the feeding ratio of the raw material monomers of the acrylic polymer B by the Fedors equation is preferably 9.5 to 11.0 (cal/cm ³ ) ^1/2 , and 9.7. The aqueous resin dispersion according to any one of [1] to [19], which is more preferably up to 10.1 (cal/cm ³ ) ^1/2 .
[21] The glass transition temperature of the acrylic polymer B is preferably -40°C or higher and -2°C or lower, more preferably -40°C or higher and lower than -6°C, further preferably -40°C or higher and lower than -10°C. ] The aqueous resin dispersion according to any one of [20].
[22] The mass ratio of the urethane polymer A to the acrylic polymer B is preferably 20:80 to 90:10, more preferably 40:60 to 70:30, [1] to [21]. Aqueous resin dispersion according to any one of.
[23] The particles are core-shell particles having a core layer and a shell layer, wherein the core layer contains the urethane polymer A and the shell layer contains the acrylic polymer, [1] to [22] ] The aqueous resin dispersion as described in any one of ].
[24] The acrylic polymer B is produced by polymerization using a radical polymerization initiator of 0.35% by mass or less with respect to the total amount of the radically polymerizable monomers for constituting the acrylic polymer B [1] ] The method for producing an aqueous resin dispersion according to any one of [23].
[25] The method according to any one of [1] to [23], wherein the urethane polymer A is used as a seed and a radically polymerizable monomer for forming the acrylic polymer B is seed-polymerized to produce the particles. A method for producing the described aqueous resin dispersion.
[26] The method for producing an aqueous resin dispersion according to [24] or [25], wherein the polymerization temperature is preferably 10 to 90°C, more preferably 30 to 70°C.
[27] The amount of the radical polymerization initiator used in the polymerization is preferably 0.01 to 5% by mass, more preferably 0.05 to 2%, based on the total amount of radically polymerizable monomers for constituting the acrylic polymer B. The method for producing an aqueous resin dispersion according to any one of [24] to [26], which is more preferably 0.10 to 1% by mass, more preferably 0.10 to 1% by mass. [28] An ink containing the aqueous resin dispersion according to any one of [1] to [23].
[29] The ink of [28], further comprising a pigment paste.
[30] Use of the aqueous resin dispersion according to any one of [1] to [23] for producing an ink.
[31] The use according to [30], wherein the ink comprises the aqueous resin dispersion according to any one of [1] to [23].
[32] Use according to [30] or [31], wherein the ink comprises a pigment paste.

According to the present invention, when used as a raw material for a water-based ink, the water-based resin dispersion has a low viscosity, is excellent in coatability, and provides a coating film having good adhesion to various plastic film substrates and good gloss. An ink containing the dispersion can be provided.

In the present invention, "(meth)acrylate" is a generic term for acrylate and methacrylate. "(Meth)acrylic acid" is a generic term for acrylic acid and methacrylic acid.
A “monomer-derived structural unit” means a monomer-derived structural unit constituting a polymer.
"Solid content" means non-volatile components at 0.1 MPa and 105°C.

The aqueous resin dispersion of the present invention contains urethane polymer A and acrylic polymer B within the same particle. The aqueous resin dispersion may further contain components such as additives in addition to the polymer A and the polymer B.

<Urethane polymer A>
Urethane polymer A is a polymer having urethane bonds obtained by reacting polyol a with polyisocyanate b.

The urethane polymer A promotes film formation of the aqueous coating composition and imparts adhesion of the obtained coating film to a polar substrate such as polyethylene terephthalate. The content of the acrylic polymer B with respect to the total mass of the urethane polymer A and the acrylic polymer B is preferably 10 to 80% by mass, more preferably 20 to 50% by mass. Within the above range, the more the acrylic polymer B, the better the adhesion to the low-polarity substrate, the better the miscibility with the low-molecular-weight alcohol, the lower the viscosity of the aqueous coating composition, and the better the coatability. Tend. In addition, the smaller the content, the more the film-forming property of the coating film, the adhesion to the polar substrate, and the dispersion stability of the aqueous resin dispersion tend to improve.

As the urethane polymer A, a urethane polymer having an average particle size and molecular weight that can be mixed with the (meth)acrylic monomer used in the synthesis of the acrylic polymer B is preferable. As the urethane polymer, a commercially available aqueous urethane emulsion may be used as it is. Specifically, Sumika Covestro Urethane Co., Ltd.: Bihydrol UH2606, Bihydrol UH650, Bihydrol UHXP2648/1, Bihydrol UHXP2650, Impranil DLE, Impranil DLC-F, Impranil DLN, Impranil DLN-W50, Implanel Neal DLP-R, Implaneal DLS, Implaneal DLU, Implaneal XP2611, Implaneal LP RSC 1380, Implaneal LP RSC 1537, Implaneal LP RSC 1554, Implaneal LP RSC 3040; manufactured by Dainippon Ink and Chemicals Co., Ltd. : Hydran HW-301, HW-310, HW-311, HW-312B, HW-333, HW-340, HW-350, HW-375, HW-920, HW-930, HW-940, HW-950, HW-970, AP-10, AP-20, ECOS3000; Sanyo Chemical Industries Co., Ltd.: Uprene UXA-3005, Chemitylene GA-500; Daiichi Kogyo Seiyaku Co., Ltd.: Superflex 110, Superflex 150, Superflex 260S, Superflex 210, Superflex 420, Superflex 500M; Manufactured by ADEKA CORPORATION: ADEKA BONTITER UHX-210, ADEKA BONTITER UHX-280; Manufactured by Mitsui Chemicals, Inc.: Takelac W-4000, Takelac W- Commercially available products such as 6010 and Takelac W-6110 may also be used.

The polyol a is an organic compound having at least two hydroxyl groups in one molecule, and various polyols can be used.
Specific examples of the polyol a include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6 - low molecular weight polyols such as hexanediol, neopentyl glycol, diethylene glycol, trimethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, hexanediol, cyclohexanedimethanol; and at least one of said low molecular weight polyols; , ethylene oxide, propylene oxide, tetrahydrofuran, etc.; and at least one of the low-molecular-weight polyols, adipic acid, sebacic acid, itaconic acid, maleic anhydride, terephthalic acid, isophthalic acid, etc. Polyester polyol obtained by polycondensation with dicarboxylic acid, polyether polyol such as polyethylene glycol, polypropylene glycol, polycaprolactone polyol, polytetramethylene ether polyol, polycarbonate polyol; other polybutadiene polyol, hydrogenated polybutadiene polyol, polyacrylic Examples include acid ester polyols.
These may be used individually by 1 type, and may use 2 or more types together.

The polyisocyanate b is an organic compound having at least two isocyanate groups in one molecule, and various polyisocyanates can be used.
Specific examples of the polyisocyanate b include ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), dodecamethylene diisocyanate, 1,6,11-undecane triisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, and lysine. Diisocyanate, 2,6-diisocyanatomethylcaproate, bis(2-isocyanatoethyl)fumarate, bis(2-isocyanatoethyl)carbonate, 2-isocyanatoethyl-2,6-diisocyanatohexanoate, etc. of aliphatic polyisocyanates; isophorone diisocyanate (IPDI), 4,4′-dicyclohexylmethane diisocyanate (hydrogenated MDI), cyclohexylene diisocyanate, methylcyclohexylene diisocyanate (hydrogenated TDI), bis(2-isocyanatoethyl)-4 -cyclohexene-1,2-dicarboxylate, 2,5-norbornane diisocyanate, 2,6-norbornane diisocyanate and other cycloaliphatic polyisocyanates; 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 2,4- tolylene diisocyanate (TDI), 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate (MDI), 2,4-diphenylmethane diisocyanate, 4,4'-diisocyanatobiphenyl, 3,3'-dimethyl- 4,4'-diisocyanatobiphenyl, 3,3'-dimethyl-4,4'-diisocyanatodiphenylmethane, 1,5-naphthylene diisocyanate, 4,4',4''-triphenylmethane triisocyanate, aromatic polyisocyanates such as m-isocyanatophenylsulfonyl isocyanate and p-isocyanatophenylsulfonyl isocyanate;
These may be used individually by 1 type, and may use 2 or more types together.

Examples of the method for producing the urethane polymer A include a method in which the polyol a and the polyisocyanate b are reacted in an ether such as dioxane using a catalyst such as dibutyltin dilaurate.

<Acrylic polymer B>
The acrylic polymer B has structural units derived from (meth)acrylic monomers. The polymer B may contain structural units derived from radically polymerizable monomers other than (meth)acrylic monomers. Radically polymerizable monomer is a monomer having a radically polymerizable group, radically polymerizable carbon-carbon unsaturated double bond, radically polymerizable carbon-carbon unsaturated triple bond, radical ring-opening Examples thereof include monomers having a polymerizable ring and the like.

The acrylic polymer B is a component that has the function of improving miscibility with low-molecular-weight alcohols and imparting adhesion of the obtained coating film to low-polarity substrates such as polypropylene. The acrylic polymer B has a structural unit derived from the radically polymerizable monomer c having an alicyclic skeleton, and optionally another vinyl-based monomer d copolymerizable with the monomer c. You may have a structural unit derived from. The acrylic polymer B preferably has 5% by mass or more, more preferably 10% by mass or more, and preferably 30% by mass or more of a radically polymerizable monomer-derived structural unit having an alicyclic skeleton. More preferred. Within the above range, the more structural units derived from the radical polymerizable monomer having an alicyclic skeleton, the more the dispersion stability of the aqueous resin dispersion is improved, and the resulting coating film adheres to the low-polarity substrate. tend to endow. Further, as the number of structural units derived from the radically polymerizable monomer having an alicyclic skeleton increases, the miscibility with the low-molecular-weight alcohol of the aqueous resin dispersion improves, and the viscosity of the aqueous coating composition becomes low, resulting in improved coatability. At the same time, the gloss tends to be improved. In addition, the less structural units derived from the radically polymerizable monomer having an alicyclic skeleton, the better the film-forming properties of the aqueous coating composition, and the better the adhesion of the obtained coating film to the polar substrate. tend to

Specific examples of the radically polymerizable monomer c having an alicyclic skeleton include cyclohexyl (meth)acrylate, 3,4-epoxycyclohexyl (meth)acrylate, isobornyl (meth)acrylate and 4-t-butylcyclohexyl ( meth)acrylate and the like. Among these, cyclohexyl (meth)acrylate is preferable from the viewpoint of easiness of polymerization when producing the polymer B.

Another vinyl-based monomer d copolymerizable with the radically polymerizable monomer c having an alicyclic skeleton is a component that adjusts the physical properties and characteristics of the acrylic polymer B. Specific examples of the other vinyl-based monomer d include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, t-butyl (meth) acrylate. , 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate and other alkyl (meth)acrylates having 1 to 18 carbon atoms in the alkyl group; 2-hydroxyethyl (meth)acrylate, 2-hydroxy hydroxyalkyl (meth)acrylates such as propyl (meth)acrylate; glycol di(meth)acrylates such as ethylene glycol di(meth)acrylate and butylene glycol (meth)acrylate; alkylamino (meth)acrylates such as dimethylaminoethyl (meth)acrylate; ) acrylates; monomers having an acid group such as (meth)acrylic acid, vinylsulfonic acid, styrenesulfonic acid and neutralized salts thereof; dimethylaminoethyl (meth)acrylate methyl chloride salt, allyl (meth)acrylate, tri Vinyl group-containing monomers such as methylolpropane tri(meth)acrylate, glycidyl(meth)acrylate, styrene, vinyl acetate, vinyl propionate, and (meth)acrylonitrile can be used. Adhesion to a polar substrate and dispersion stability of the aqueous resin dispersion can be improved by using the monomer having an acid group.

The glass transition temperature (Tg) (unit: °C) of the acrylic polymer B means a value calculated by Fox's formula shown in formula (1) below.

Abbreviations in formula (1) are as follows.
Wi: Mass fraction of monomer i Tgi: Tg (°C) of homopolymer of monomer i
For the Tg of the homopolymer, the numerical value described in "Polymer Handbook 4th Edition by John Wiley &Sons" can be used. As the Tg of a homopolymer not described in the polymer handbook, a value obtained by actually measuring the Tg with a differential scanning calorimeter can be used.

The glass transition temperature of the acrylic polymer B is -60°C or higher and lower than 5°C, preferably -40°C or higher and -2°C or lower, more preferably -40°C or higher and lower than -6°C, and -40°C or higher and -10°C. Less than is particularly preferred. Within the above range, the blocking resistance tends to improve as the glass transition temperature increases. In addition, the lower the glass transition temperature, the better the adhesion to the low-polarity substrate and the better the gloss tends to be. The glass transition temperature of the acrylic polymer B is adjusted by, for example, increasing the ratio of structural units derived from long-chain alkyl (meth)acrylates such as lauryl (meth)acrylate and stearyl (meth)acrylate to lower the glass transition temperature. can be the value of, short-chain alkyl (meth) acrylates such as methyl (meth) acrylate and ethyl (meth) acrylate, or (meth) acrylates with rigid structures such as isobornyl (meth) acrylate A higher glass transition temperature can be obtained by increasing the ratio of the structural units. Further, when butyl acrylate and cyclohexyl methacrylate are used as monomers, the glass transition temperature can be lowered by increasing the ratio of structural units derived from butyl acrylate. Higher glass transition temperature values can be obtained by increasing the proportion of units.
The SP value calculated from the feed ratio of the raw material monomers of the acrylic polymer B by the Fedors estimation formula is preferably from 9.5 to 11.0 (cal/cm ³ ) ^1/2 , and from 9.7 to 10.5. 1 (cal/cm ³ ) ^1/2 is more preferable. Within the above range, there is a tendency that the larger the SP value, the better the adhesion of the coating film to the polar substrate. Also, the smaller the size, the better the miscibility with the low-molecular-weight alcohol, and the lower the viscosity of the water-based coating composition, the better the coatability.

As a method for producing the aqueous resin dispersion of the present invention containing the urethane polymer A and the acrylic polymer B in the same particles, for example, a radical having an alicyclic skeleton is prepared in the presence of an aqueous medium and the urethane polymer A. An aqueous resin obtained by polymerizing a polymerizable monomer c and, as an optional component, another vinyl-based monomer d copolymerizable with the monomer c, and containing a urethane polymer A and an acrylic polymer B in the same particle. Mention may be made of the method of producing the dispersion liquid (seeded polymerization). The particles contained in the aqueous resin dispersion liquid obtained by seed polymerization are core-shell particles having a core layer (nucleus) and a shell layer (shell), the core layer containing the urethane polymer A, and the shell layer containing an acrylic resin. Core-shell particles containing a polymer may also be used.

As the radical polymerization initiator for the polymerization, a conventional radical polymerization initiator may be used. Persulfate-based initiators such as sodium persulfate, potassium persulfate and ammonium persulfate, t-butyl hydroperoxide, dilauroyl peroxide, t-butyl peroxy-2-ethylhexanoate, t-butyl peroxy Organic peroxide initiators such as barate can be used. A redox polymerization initiator obtained by combining an organic peroxide initiator or a persulfate initiator with a reducing agent such as ascorbic acid, Rongalite or metal sulfite can also be used. The amount of the radical polymerization initiator used is preferably 0.01 to 5% by mass, and 0.05 to 2% by mass, based on the total mass of the (meth)acrylic monomer and the other monomer d. % is more preferred. Within the above range, the larger the amount of the radical polymerization initiator used, the lower the molecular weight of the acrylic polymer B, which tends to improve the wettability to the substrate. Also, the smaller the amount of the radical polymerization initiator used, the higher the molecular weight of the acrylic polymer B, which suppresses the swelling of the particles due to the low-molecular-weight alcohol, and the lower the viscosity of the aqueous coating composition. In addition, the smaller the amount of the radical polymerization initiator used, the more the cohesive force of the coating film tends to improve. The molecular weight of acrylic polymer B can be adjusted, for example, by adding an appropriate amount of a chain transfer agent such as n-dodecylmercaptan, 1-octanethiol, or 2-ethylhexyl thioglycolate during polymerization.

The polymerization temperature for the polymerization is preferably 10 to 90°C, more preferably 30 to 70°C. Within the above range, the higher the polymerization temperature, the more the polymerization reaction is accelerated and the amount of low-molecular-weight components can be efficiently reduced. In addition, the lower the polymerization temperature, the more energy required for the polymerization process can be reduced. The polymerization is generally almost completed by maintaining the temperature at about 40 to 90° C. for about 30 minutes to 3 hours after the end of heat generation.

The emulsion can be further stabilized by using an emulsifier as necessary during the polymerization. The amount of the emulsifier used is generally preferably 0.05 to 10% by mass, more preferably 0.1 to 5% by mass, based on the total mass of monomers used as starting materials for polymerization. Within the above range, the greater the amount of the emulsifier used, the more the dispersion stability of the dispersion tends to improve. Also, the smaller the amount of the emulsifier used, the more the adhesion to the low-polarity substrate tends to improve. Anionic, cationic, and nonionic surfactants can be used as the emulsifier.
These may be used individually by 1 type, and may use 2 or more types together.

Specific examples of the anionic surfactant include potassium oleate, sodium laurate, sodium dodecylbenzenesulfonate, sodium alkanesulfonate, sodium alkylnaphthalenesulfonate, sodium dialkylsulfosuccinate, sodium polyoxyethylene alkyl ether sulfate, Non-reactive surfactants such as sodium polyoxyethylene alkylallyl ether sulfate, polyoxyethylene alkyl phosphate, polyoxyethylene alkyl allyl phosphate, and alkyl allyl sulfosuccinate (e.g. Sanyo Chemical Co., Ltd.: Eleminol (registered Trademark) JS-2, manufactured by Kao Corporation: Latemul (registered trademark) S-180A, S-180), polyoxyethylene alkylpropenylphenyl ether sulfate ester ammonium salt (for example, Daiichi Kogyo Seiyaku Co., Ltd.) Manufactured by: Aqualon (registered trademark) HS-10, HS-5, BC-10, BC-5), α-sulfo-ω-(1-(nonylphenoxy)methyl-2-(2-propenyloxy ) Ethoxy)-poly(oxy-1,2-ethanediyl) ammonium salt (for example, manufactured by Asahi Denka Kogyo Co., Ltd.: Adekaria Soap (registered trademark) SE-10, SE-1025A), polyoxyethylene- 1-(allyloxymethyl)alkyl ether sulfate ester ammonium salt (for example, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.: Aqualon (registered trademark) KH-10), α-sulfo-ω-(1-(alkoxy) Methyl-2-(2-propenyloxy)ethoxy)-poly(oxy-1,2-ethanediyl)ammonium salt (for example, manufactured by ADEKA Co., Ltd.: Adekaria Soap (registered trademark) SR-10, SR-1025) ), polyoxyalkylene alkenyl ether sulfate ammonium salt (for example, Latemul (registered trademark) PD-104 manufactured by Kao Corporation), and other reactive surfactants.
Specific examples of the cationic surfactant include non-reactive surfactants such as stearylamine hydrochloride, lauryltrimethylammonium chloride, and trimethyloctadecylammonium chloride.

Specific examples of the nonionic surfactant include non-reactive surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkylallyl ethers, polyoxyethyleneoxypropyl block polymers, polyethylene glycol fatty acid esters, polyoxyethylene sorbitan fatty acid esters, and the like. Activator, α-hydro-ω-(1-alkoxymethyl-2-(2-propenyloxy)ethoxy)-poly(oxy-1,2-ethanediyl) (manufactured by Asahi Denka Kogyo Co., Ltd.: Adekaria Soap ER- 10, ER-20, ER-30, ER-40), polyoxyethylene alkylpropenyl phenyl ether (Daiichi Kogyo Seiyaku Co., Ltd.: Aqualon RN-20, RN-30, RN-50), polyoxyalkylalkenyl Reactive surfactants such as ethers (manufactured by Kao Corporation: Latemul PD-420, PD-430, PD-450) and the like.

The acid value of the aqueous resin dispersion containing the urethane polymer A and the acrylic polymer B in the same particles is preferably 3 to 40 mgKOH/g, more preferably 5 to 20 mgKOH/g. Within the above range, the higher the acid value, the better the dispersion stability of the dispersion, and the lower the acid value, the better the miscibility with the low-molecular-weight alcohol, the lower the viscosity of the aqueous coating composition, and the better the coatability. tend to Including the urethane polymer A and the acrylic polymer B in the same particle can be obtained by staining an ultra-thin section prepared by a general gel embedding method with ruthenium oxide and observing it using a transmission electron microscope. can be determined by

The hydrodynamic average particle size of the aqueous resin dispersion containing the urethane polymer A and the acrylic polymer B in the same particle is preferably 30 to 150 nm, more preferably 40 to 100 nm. Within the above range, the smaller the hydrodynamic average particle size, the better the pigment dispersibility, and the larger the value, the lower the viscosity of the dispersion and the viscosity of the water-based coating composition, which tends to improve the coatability.
Here, the "hydrodynamic average particle size" is measured at room temperature using a particle size distribution measuring device using the photon correlation method (for example, a concentrated particle size analyzer FPAR-1000 manufactured by Otsuka Electronics Co., Ltd.), and the cumulant It means the value of the harmonic mean particle size based on the scattered light intensity calculated by analysis.

Although the main solvent of the ink composition containing the water-based resin dispersion is water, it may contain a solvent other than water. Examples of solvents other than water include alcohol-based solvents, glycol-based solvents, and carbitol-based solvents.
These may be used individually by 1 type, and may use 2 or more types together.
The content of solvents other than water is preferably 3 to 60% by mass, more preferably 5 to 50% by mass, based on the total mass of all solvents. Within the above range, the higher the content of the solvent other than water, the better the film formability of the aqueous coating composition and the better the gloss tends to be. Moreover, the higher the content of the solvent other than water, the more the drying properties of the coating film tend to improve. Also, the smaller the content of the solvent other than water, the lower the viscosity of the aqueous coating composition, which tends to improve the coatability.

The ink composition containing the water-based resin dispersion can be produced by blending the pigment and the solvent with the water-based resin dispersion of the present invention, and may contain an adjuvant as a compounding component. Examples of the adjuvant include acrylic pigment dispersing resins, antifoaming agents such as silicone resins, lubricants such as polyethylene waxes, surfactants, leveling agents, and preservatives.

The ink of the present invention containing the aqueous resin dispersion can be produced by mixing a pigment, a resin and water. Examples of the method for producing the ink include a method including the following varnish production step, pigment dispersion step, and product finishing step.

<Varnish manufacturing process>
In the varnish manufacturing process, a pigment dispersion resin and an alcohol-containing aqueous solution are mixed. During the mixing, heating may be performed or may not be performed.
The concentration of the varnish is preferably 20 to 40% by mass from the viewpoint that the pigment paste has a viscosity that is easy to handle in the following pigment dispersing step. Also, the pH of the varnish is preferably 6-9.

<Pigment dispersion step>
In the pigment dispersion step, first, the pigment and varnish are mixed to produce a premix, and then the obtained premix is kneaded using a disperser. By kneading, the aggregated pigment is dispersed to produce a pigment paste in which the pigment dispersing resin is adsorbed on the surface of the pigment. Dispersers used for kneading include, for example, bead mills, sand mills, ball mills, attritors, and roll mills.

<Product finishing process>
In the product finishing step, the pigment paste and the aqueous resin dispersion are mixed to produce an ink composition. In the product finishing process, if necessary, a diluent containing at least one of water and an organic solvent may be added to adjust the solid content concentration of the ink.
When the ink contains the adjuvant, the adjuvant can also be appropriately blended in the product finishing process. Moreover, the adjuvant can also be blended in a process prior to the product finishing process.

The ink is suitably used when printing on the surface of a printing medium such as a resin film, a resin molding, or paper.
Examples of methods for printing the ink include gravure printing, offset printing, flexographic printing, inkjet printing, spray coating, roller coating, bar coating, air knife coating, casting, and brush coating. , dipping method.
Drying conditions after forming the ink coating film may be appropriately selected according to the printing method or the like. For example, when gravure printing is performed on a resin film, drying is preferably performed at a temperature in the range of 20 to 60° C. for 10 seconds to 10 hours.

The present invention will be described in detail below with examples and comparative examples, but the present invention is not limited to these. "Parts" and "%" in Examples and Comparative Examples mean "parts by mass" and "% by mass", respectively.

<Synthesis Example 1> Production of water-based resin dispersion containing urethane polymer A and acrylic polymer B in the same particles Water-based urethane resin Bihydrol UH2648/1 (manufactured by Sumika Covestro Urethane Co., Ltd., solid content 35.0%) as a dispersion with a solid content concentration of 35.0% 285.7 parts (solid content 100.0 parts) , 247 parts of deionized water, 79.0 parts of cyclohexyl acrylate (hereinafter abbreviated as CHA), and 21.0 parts of butyl acrylate (hereinafter abbreviated as BA) (meth)acrylic monomers were charged, and the flask was The temperature was raised to 40°C. Then, 0.02 parts of a t-butyl hydroperoxide aqueous solution (manufactured by Arkema Yoshitomi Co., Ltd., trade name: Luperox TBH68X, solid content 68%) as a polymerization initiator, and 0.0002 parts of ferrous sulfate as a reducing agent. , 0.00027 parts of ethylenediaminetetraacetic acid (EDTA), 0.082 parts of sodium isoascorbate monohydrate, and 4 parts of deionized water were added. Subsequently, after confirming the heat of polymerization at 0.5° C., 0.03 parts of t-butyl hydroperoxide aqueous solution and 20 parts of deionized water were added dropwise for 15 minutes. After confirming the peak top temperature due to polymerization heat generation, the inner temperature of the flask was raised to 60 ° C., 0.05 parts of t-butyl hydroperoxide aqueous solution, 0.082 parts of sodium isoascorbate monohydrate and deionized water 4 parts were added in two portions. After that, the reaction solution was cooled to obtain an aqueous resin dispersion containing urethane polymer A and acrylic polymer B in the same particles and having a solid concentration of 30%. Table 1 shows the synthesis results of the resulting aqueous resin dispersion and the form of the resin.

<Synthesis Examples 2 to 9> Production of aqueous resin dispersions containing urethane polymer A and acrylic polymer B in the same particles The same procedure as in Synthesis Example 1 was performed except that the monomer composition ratios shown in Table 1 were used. By doing so, an aqueous resin dispersion having a solid concentration of 30% containing urethane polymer A and acrylic polymer B in the same particles was obtained. Table 1 shows the synthesis results of the resulting aqueous resin dispersion and the form of the resin.

<Synthesis Example 10> Production of aqueous resin dispersion mixture of urethane polymer A and acrylic polymer B not containing urethane polymer A and acrylic polymer B in the same particles Stirrer, reflux condenser, temperature controller and dropping pump 180 parts of deionized water and Adekaria Soap SR-1025 (manufactured by ADEKA Co., Ltd., solid content 25.0%) 3.8 parts as a dispersion with a solid content concentration of 25.0% (solid content 0 .95 parts) was charged, and the internal temperature of the flask was raised to 80°C. 0.5 hours after the temperature stabilized, 2.5 parts of cyclohexyl methacrylate (hereinafter abbreviated as CHMA), 2.5 parts of BA, 2.0 parts of deionized water and 0.19 parts of Adekari Soap SR-1025 were added. A pre-emulsion liquid emulsified and dispersed in advance and 1.0 part of deionized water were prepared and stirred for 0.5 hour. Thereafter, an aqueous polymerization initiator solution prepared by dissolving 0.3 parts of ammonium persulfate in 3.0 parts of deionized water was added as a polymerization initiator. After confirming the peak top temperature due to polymerization heat generation, and after the internal temperature returned to 80° C., 47 parts of CHMA, 47 parts of BA, 38 parts of deionized water, and 3.6 parts of Adekaria Soap SR-1025 were emulsified and dispersed in advance to form a pre-emulsion. The liquid was added dropwise over 2 hours and 30 minutes. The internal temperature was maintained at 80°C during the dropwise addition. Stirring was continued for 1 hour and 30 minutes from the end of the dropwise addition while maintaining the internal temperature at 80° C., and then the reaction liquid was cooled to obtain an acrylic polymer B water-based resin dispersion having a solid content concentration of 30%. Bihydrol UH2648/1 as a urethane polymer A water-based resin dispersion and the acrylic polymer B water-based resin dispersion are mixed in equal amounts to obtain a urethane polymer A that does not contain urethane polymer A and acrylic polymer B in the same particles. and an aqueous resin dispersion mixture of acrylic polymer B was obtained. Table 1 shows the synthesis results of the obtained aqueous resin dispersion mixture and the form of the resin.

<Preparation of dispersant>
900 parts of deionized water, 60 parts of sodium 2-sulfoethyl methacrylate, 10 parts of potassium methacrylate, and 12 parts of methyl methacrylate (hereinafter abbreviated as MMA) are placed in a polymerization apparatus equipped with a stirrer, a condenser, and a thermometer. The temperature was raised to 50° C. while the inside of the polymerization apparatus was being replaced with nitrogen. Next, 0.08 part of 2,2'-azobis(2-methylpropionamidine) dihydrochloride was added as a polymerization initiator, and the temperature was raised to 60°C. After raising the temperature, a dropping pump was used to continuously drop MMA at a rate of 0.24 parts/minute for 75 minutes. The total amount of MMA added dropwise was 18 parts. After completion of dropping, the reaction solution was held at 60° C. for 6 hours and then cooled to room temperature to obtain a dispersant having a solid concentration of 10% as a transparent aqueous solution.

<Production of pigment dispersion resin>
145 parts of deionized water, 0.1 part of sodium sulfate, and 0.25 part of the dispersant (solid concentration: 10%) are placed in a polymerization apparatus equipped with a stirrer, a cooling tube, and a thermometer, and stirred to homogenize. aqueous solution. Next, 13 parts of MMA, 10 parts of styrene (hereinafter abbreviated as St), 67 parts of n-butyl methacrylate (hereinafter abbreviated as n-BMA), and 10 parts of methacrylic acid (hereinafter abbreviated as MAA) are added and stirring is started again. and 0.5 parts of 2,2-dimethyl-2,2-diazenediyldibutanenitrile (hereinafter abbreviated as AMBN) and 1.9 parts of n-dodecylmercaptan (hereinafter abbreviated as n-DM), 1-octane 1.9 parts of thiol (hereinafter abbreviated as n-OM) and 1.9 parts of 2-ethylhexyl thioglycolic acid (hereinafter abbreviated as OTG) were added and the temperature was raised to 80°C, and the reaction temperature was raised to 80-85°C. After that, the temperature was raised to 95° C. and maintained for 1 hour to complete the reaction. The resulting pigment dispersion resin had a molecular weight of 8,000 and an acid value of 61 mgKOH/g.

<Dissolution and Neutralization of Pigment Dispersion Resin>
In a 200 ml flask equipped with a stirrer and a thermometer, 90 g of the pigment dispersion resin, 81.3 g of isopropyl alcohol (hereinafter abbreviated as IPA), and 120 g of deionized water were added, stirring was started, and dimethylaminoethanol (hereinafter, DMAE abbreviated) was gradually added. Thereafter, the temperature was maintained at room temperature (25° C.) for 2 hours to complete dissolution, and the pigment dispersion resin was neutralized with dimethylaminoethanol to obtain a pigment dispersion resin varnish.

(Example 1)
Take 45 g of the varnish of the pigment dispersion resin, 9.0 g of TEGO740 (manufactured by Evonik) as a pigment dispersant, 157.5 g of pigment (titanium oxide manufactured by Ishihara Sangyo Co., Ltd., trade name: CR-90), deionized water 36.0 g, IPA 67.5 g, and glass beads 60.0 g were mixed and stirred in this order to obtain a premix. The premix was kneaded for 3 hours using a rocking shaker to obtain a pigment paste. The dispersity of the pigment paste was evaluated using a particle cage. Then, 20 g of the pigment paste was taken, 8.6 g of the aqueous resin dispersion obtained in Synthesis Example 1 was added, and thoroughly stirred to prepare an ink. The ink was diluted with 10.3 g of IPA and 12.6 g of pure water. Using the diluted ink, a biaxially oriented polypropylene (hereinafter abbreviated as OPP) film (manufactured by Toyobo Co., Ltd., trade name: P-2108) and It was printed on the corona-treated surface of a polyethylene terephthalate (hereinafter abbreviated as PET) film (manufactured by Futamura Chemical Co., Ltd., trade name: FE2001). An ink coating film was formed to have a thickness of 1 to 2 μm. The ink coating film was dried at 25° C. for 1 day. The smoothness of the ink coating film after drying was evaluated. Table 2 shows the evaluation results of the viscosity of the ink, the smoothness of the coating film, the glossiness, and the adhesion to various substrates. In addition, the evaluation method is as follows.

[Ink viscosity]
The viscosity of the blended ink at 23°C was measured by Zahn cup No. 3 (manufactured by Tester Sangyo Co., Ltd.) to evaluate the viscosity of the ink according to the following evaluation criteria.
(Evaluation criteria)
◯: The Zahn cup passage time is less than 10 seconds, the viscosity is low, and the coatability is excellent.
x: The Zahn cup passage time is 10.0 seconds or more, and the viscosity is high and the application property is poor.

[Gloss]
By measuring the gloss (60°) of the ink coating film with a thickness of 1 to 2 μm after drying using a variable angle gloss meter (manufactured by Nippon Denshoku Industries Co., Ltd., trade name: GLOSS METER VG7000), the following evaluation was performed. Gloss was evaluated according to a standard.
(Evaluation criteria)
A: The gloss value is 11.5 or more.
Good: The gloss value is 11.0 or more and less than 11.5.
Δ: The gloss value is higher than 10.5 and lower than 11.0.
x: The gloss value is 10.5 or less.

[Substrate Adhesion]
A cellophane tape (manufactured by Nichiban Co., Ltd., trade name: CT405AP-12) was attached to the ink coating film having a thickness of 1 to 2 μm after drying, and a peeling test was performed in the vertical direction. Base material adhesion was evaluated according to the standard.
(Evaluation criteria)
⊚: The substrate residual rate of the ink after the peeling test was 80% or more, and the adhesion was excellent.
○: The substrate residual rate of the ink after the peeling test was 25% or more and less than 80%, and the adhesion was good.
Δ: The substrate residual rate of the ink after the peeling test was 15% or more and less than 25%, which was at a practical level.
x: The substrate residual rate of the ink after the peeling test was less than 15%, which did not meet the practical level.

[Examples 2 to 5 and Comparative Examples 1 to 5]
Inks were produced in the same manner as in Example 1 except that the aqueous resin dispersions of Synthesis Examples 2 to 10 were used instead of the aqueous resin dispersions of Synthesis Example 1, and the same evaluation items as in Example 1 were evaluated. The evaluation results are shown in Table 2.

The abbreviations in Tables 1 and 2 mean the following.
CHMA: cyclohexyl (meth)acrylate CHA: cyclohexyl acrylate IBXA: isobornyl acrylate BA: n-butyl acrylate St: styrene

Examples 1 to 5 using the ink of the present invention containing the aqueous resin dispersion of the present invention have low viscosity of the ink and excellent coatability, excellent smoothness and gloss of the ink coating after drying, and OPP Adhesion to the substrate and PET substrate was also good.
In Comparative Examples 1 and 4, in which the acrylic polymer having a glass transition temperature outside the range specified in the present application was used, the gloss of the ink coating film after drying was poor.
On the other hand, in Comparative Examples 2 and 3 using an acrylic polymer having no structural unit derived from a radically polymerizable monomer having an alicyclic skeleton, the adhesion of the dried ink film to the substrate and One of the glosses was bad.
Comparative Example 5, which used an aqueous resin dispersion containing no urethane polymer A and acrylic polymer B in the same particles, had a high ink viscosity and poor applicability.

The aqueous resin dispersion of the present invention and the ink containing the dispersion have low viscosity and excellent coatability, and can provide a coating film having good adhesion to various plastic film substrates and good gloss. It can be suitably used as a raw material for aqueous coating compositions such as, and is extremely important industrially.

Claims (9)

The urethane polymer A and the acrylic polymer B are contained in the same particle, the acrylic polymer B has a structural unit derived from a radically polymerizable monomer having an alicyclic skeleton, and the glass transition of the acrylic polymer B An aqueous resin dispersion having a temperature of -60°C or higher and lower than 5°C. 2. The method according to claim 1, wherein the acrylic polymer B contains 5% by mass or more of the structural units derived from a radically polymerizable monomer having an alicyclic skeleton, based on the total mass of the structural units constituting the acrylic polymer B. The aqueous resin dispersion described. The aqueous resin dispersion according to claim 1 or claim 2, wherein the acrylic polymer B has a glass transition temperature of -40°C or higher and -2°C or lower. The aqueous resin dispersion according to any one of claims 1 to 3, wherein the acrylic polymer B has a glass transition temperature of -40°C or higher and -6°C or lower. The aqueous resin dispersion according to any one of claims 1 to 4, wherein the aqueous resin dispersion has a hydrodynamic average particle size of 120 nm or less as measured by a dynamic light scattering method. The aqueous resin dispersion according to any one of claims 1 to 5, wherein the solid content of the aqueous resin dispersion is 35% by mass or more with respect to the total mass of the aqueous resin dispersion. Claims 1 to 6, wherein the acrylic polymer B is produced by polymerization using a radical polymerization initiator of 0.35% by mass or less with respect to the total amount of radically polymerizable monomers for constituting the acrylic polymer B. A method for producing an aqueous resin dispersion according to any one of. The water-based resin dispersion according to any one of claims 1 to 6, wherein the particles are produced by seed polymerization of a radically polymerizable monomer for constituting the acrylic polymer B using the urethane polymer A as a seed. body manufacturing method. An ink containing the aqueous resin dispersion according to any one of claims 1 to 6.