JP7159740B2 - Core-shell type aqueous biomass emulsions, and aqueous binder resins and aqueous coating varnishes for printing inks containing core-shell type aqueous biomass emulsions - Google Patents

Description

The present invention relates to a core-shell type aqueous biomass emulsion that uses plant-derived resources and has excellent adhesion to paper and films, and to an aqueous binder resin for printing ink and an aqueous coating varnish containing the core-shell type aqueous biomass emulsion.

In recent years, due to growing interest in environmental conservation, attempts have been made to switch to materials using bio-derived resources with less environmental impact. Among them, the use of plant-derived biomass resources is said to be effective in saving petroleum resources and reducing carbon dioxide emissions. Also, in the printing industry, by switching printing inks, varnishes, etc. from oil-based to water-based, measures against environmental impact are being promoted.

Along with this, ink manufacturers are trying to differentiate between existing ink products and so-called biomass inks by obtaining approval from certification bodies or establishing voluntary standards. For example, according to the acquisition criteria for the "Biomass Mark" certified by the Japan Organic Resources Association, the degree of biomass (in the case of ink, the ratio of raw materials of biological origin contained in the ink) is the lower limit of 10 in dry weight. % is regarded as an environmental product, and this is one indicator of biomass ink.

An example of using a rosin-based compound as an aqueous biomass material is a method for producing a rosin-based compound-containing emulsion obtained by atomizing a rosin-based compound, a monomer and an emulsifier in an aqueous medium, followed by emulsion polymerization (Patent Document 1) or a method of obtaining an emulsion polymer by emulsion polymerizing monomers in the presence of a rosin support resin having an acid value of 120 to 250 obtained by esterifying a polyol to a reinforced rosin such as fumarated rosin and a surfactant. (Patent Document 2), or in the presence of a neutralized primary polymer obtained by polymerizing a radically polymerizable monomer containing a carboxyl group-containing monomer and an aromatic monomer and rosin and a method for producing an aqueous dispersion obtained by emulsion polymerization of a radically polymerizable monomer containing an aromatic monomer (Patent Document 3).

However, the aqueous biomass emulsions obtained by these methods are not sufficiently satisfactory in adhesion to paper and films. In addition, materials using rosin generally have a problem of a peculiar odor derived from rosin. Odor problems arise not only after coating as printing ink or varnish, but also during the manufacturing process. The aqueous biomass emulsion obtained by the above method has not been able to improve the odor problem.

JP-A-2002-97213 JP-A-6-206912 Japanese Patent Application Laid-Open No. 2002-256011

An object of the present invention is to provide a core-shell type aqueous biomass emulsion that uses a high content of rosin as a plant-derived resource, has little odor peculiar to rosin, and has excellent adhesion to paper and films. Another object of the present invention is to provide an aqueous binder resin for printing ink and an aqueous coating varnish containing the core-shell type aqueous biomass emulsion.

The present inventors have found that a modified rosin alkali salt having a specific molecular weight is used as a biomass material, and a core-shell type emulsion containing a water-soluble synthetic resin alkali salt and a modified rosin alkali salt on the shell side. The present inventors have completed the present invention based on the finding that the adhesiveness to paper and film is excellent with little peculiar odor.

That is, the present invention
<1> Water, (A) modified rosin alkali salt, (B) styrene-acrylic resin, acrylic resin, styrene-maleic acid resin, and styrene-acrylic-maleic acid resin. a soluble synthetic resin alkali salt, and (C) an emulsion polymer of a monomer having a vinyl group, wherein the components (A) and (B) constitute the shell portion, the component (C) constitutes the core portion, and the ( The modified rosin contained in component A) has a number average molecular weight of 250 to 5,000, and the modified rosin is contained in an amount of 20 to 55% by mass in the total mass of the modified rosin, the synthetic resin and the component (C). core-shell type aqueous biomass emulsion,
<2> The core-shell type aqueous biomass emulsion according to <1> above, wherein the synthetic resin is a styrene-acrylic resin,
<3> The core-shell type aqueous biomass emulsion according to <1> or <2> above, wherein the vinyl group-containing monomer has a solubility in water of less than 3 g/100 g water at 20°C;
<4> Aqueous binder resin for printing ink containing the core-shell type aqueous biomass emulsion according to any one of <1> to <3> above,
<5> Aqueous coating varnish containing the core-shell type aqueous biomass emulsion according to any one of <1> to <3> above,
is.

The core-shell type aqueous biomass emulsion provided by the present invention has reduced rosin-specific odor and excellent adhesion to paper and film, so it can be suitably used as a binder for printing inks or a raw material for coating varnish.

The core-shell type aqueous biomass emulsion of the present invention comprises at least water, (A) a modified rosin alkali salt, and (B) a group of styrene-acrylic resins, acrylic resins, styrene-maleic acid resins, and styrene-acrylic-maleic acid resins. and (C) an emulsion polymer of a vinyl group-containing monomer.

<(A) Modified rosin alkali salt>
(A) Modified rosin alkali salt is obtained by completely or partially neutralizing the acid groups of modified rosin with an alkali substance to obtain an alkali salt. By making the denatured rosin an alkali salt, the denatured rosin can be introduced into the shell of the core-shell type aqueous biomass emulsion, resulting in better adhesion to paper and film than when the denatured rosin is introduced into the core. Become. Moreover, by introducing the modified rosin as an alkali salt into the shell, the odor can be reduced.

Modified rosins include natural rosins such as gum rosin, tall oil rosin, and wood rosin, their refined products, various modified rosins obtained by disproportionating, hydrogenating, dehydrating, dimerizing, and sulfonating the rosins, and maleic rosins to the rosins. Examples include acid-added rosin obtained by addition reaction of acid, maleic anhydride, fumaric acid, acrylic acid, etc., and partial esters or partial amidates of such acid-added rosin. From the viewpoint of dispersion stability, the modified rosin should have a number average molecular weight of 250 to 5,000. The number-average molecular weight referred to here is a value obtained as a polystyrene-equivalent molecular weight according to the GPC method using a standard polystyrene resin.

The modified rosin may have an acid value that is soluble or dispersible in water as an alkali salt, but it is preferably 100 to 250 mgKOH/g in order to stably disperse it in the shell portion. Alkaline substances include ammonia and organic amines such as ammonia, methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, propylamine, butylamine, monoethanolamine, diethanolamine, propanolamine, dimethylethanolamine, methyldiethanolamine, and morpholine. ; alkali metals such as sodium hydroxide and potassium hydroxide can be mentioned, and these are used singly or in combination of two or more. Among them, ammonia and sodium hydroxide are preferable from the viewpoint of handling of the emulsion and adhesion to the substrate. The amount of the alkaline substance to be added is desirably 50 to 150 equivalent % with respect to the acid value of the modified rosin.

<(B) Water-soluble synthetic resin alkali salt>
(B) The water-soluble synthetic resin alkali salt is an acid group of at least one synthetic resin selected from the group consisting of styrene-acrylic resin, acrylic resin, styrene-maleic acid resin, and styrene-acrylic-maleic acid resin. is solubilized in water by completely or partially neutralizing with an alkaline substance to form an alkaline salt. By using the component (B) in the shell part of the core-shell type aqueous biomass emulsion, even if the emulsion contains 10% by mass or more of the biomass material, the adhesion to the substrate is better than when a low-molecular-weight surfactant is used. It will be excellent for Among these, it is preferable to use styrene-acrylic resin because of its excellent adhesion.

Styrene-acrylic resins, acrylic resins, styrene-maleic acid resins, and styrene-acrylic-maleic acid resins are copolymers of corresponding styrene monomers, acrylic monomers, and maleic acid monomers, respectively, and contain at least an acid group ( (including those that act as acid groups during alkali neutralization, such as acid anhydrides).

Styrene monomers include, for example, styrene and α-methylstyrene.

Examples of acrylic monomers include acrylic monomers having an acid group such as (meth)acrylic acid; methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate; , (meth)acrylates such as benzyl (meth)acrylate; and (meth)acrylates having a hydroxyl group such as 2-hydroxyethyl (meth)acrylate.

Examples of maleic acid monomers include maleic anhydride, maleic acid, and maleic acid monoester obtained by monoesterifying these with alcohol.

In addition to the above-described monomers, monomers having acid groups such as itaconic acid and phosphoric acid ester group-containing monomers, and bifunctional or higher monomers such as ethylene glycol di(meth)acrylate and diethylene glycol di(meth)acrylate can be used. It may be included in the composition of monomers to be copolymerized.

The synthetic resin may have an acid value that is solubilized in water as an alkali salt, but it is preferably 50 to 350 mgKOH/g from the viewpoint of the stability of the core-shell type biomass emulsion of the present invention.

Examples of the alkaline substance include the alkaline substances used in the modified rosin alkali salt (A) described above. The amount of the alkaline substance to be added is desirably 50 to 150 equivalent % with respect to the acid value of the synthetic resin.

(A) Modified rosin alkali salt and (B) Water-soluble synthetic resin alkali salt may be separately prepared and then used to prepare the core-shell type aqueous biomass emulsion of the present invention, or may be synthesized with modified rosin. A mixture of components (A) and (B) may be prepared by adding a necessary amount of an alkaline substance to a mixture of resins. In addition, it is preferable to obtain both the components (A) and (B) as aqueous solutions for ease of handling in preparation of the core-shell type aqueous biomass emulsion of the present invention.

<(C) Emulsion Polymer of Monomer Having Vinyl Group>
(C) an emulsion polymer of a monomer having a vinyl group is a monomer that can be used for synthesizing the above-mentioned (B) copolymer constituting the water-soluble synthetic resin alkali salt; vinyl such as vinyl acetate and alkyl vinyl ether Compounds; emulsion polymerization products of monomers having at least one vinyl group selected from the group of epoxy group-containing monomers such as glycidyl (meth)acrylate and 3,4-epoxycyclohexyl (meth)acrylate. Among these, considering the balance of hydrophilicity and hydrophobicity of the emulsion that affects the uniformity of the coating film, it is an emulsion polymer of a monomer having a vinyl group with a solubility in water at 20 ° C. of less than 3 g / 100 g. is preferred. More preferably, styrene (solubility in water: 0.1 g/100 g water or less), methyl methacrylate (solubility in water: 1.0 g/100 g water), ethyl acrylate (solubility in water: 1.5 g/ 100 g water), ethyl methacrylate (solubility in water: 0.4 g/100 g water), butyl acrylate (solubility in water: 0.1 g/100 g water), butyl methacrylate (solubility in water: 0.1 g /100 g water or less), 2-ethylhexyl (meth)acrylate (water solubility: 0.1 g/100 g water or less), benzyl (meth) acrylate (water solubility: 0.1 g/100 g water or less), It is glycidyl methacrylate (solubility in water: 2.3 g/100 g water). It can be obtained by subjecting one or a combination of two or more of these to emulsion polymerization to be described later.

The core-shell type aqueous biomass emulsion of the present invention is an emulsion in which particles having a core-shell structure consisting of a hydrophilic shell portion and a hydrophobic core portion are stably dispersed in water. Specifically, (A) a modified rosin alkali salt and (B) a water-soluble synthetic resin alkali salt constitute the shell portion, and (C) an emulsion polymer of a monomer having a vinyl group constitutes the core portion. When the component (A) is introduced into the core portion, adhesion deteriorates. In addition, when the component (A) is outside the core-shell emulsion, that is, when the core-shell emulsion consisting of the components (B) and (C) is mixed with the component (A), the viscosity increases and the solid content ( That is, the mass ratio of all components (A) to (C) in the emulsion must be lowered (as a result, the physical properties of the ink and coating suitability may be adversely affected).

The method for polymerizing the core-shell type aqueous biomass emulsion of the present invention is not particularly limited. It can be obtained by emulsion polymerization. Alternatively, an aqueous solution of (A) a modified rosin alkali salt and (B) a synthetic resin alkali salt and a monomer having a vinyl group are premixed to form a monomer micelle state, followed by emulsion polymerization. be able to.

Polymerization initiators used for emulsion polymerization include known water-soluble and oil-soluble polymerization initiators, and these can be used alone or in combination of two or more.

The core-shell type aqueous biomass emulsion of the present invention can be appropriately used according to the physical properties required for inks and coating varnishes, as long as there are no problems with emulsion stability during production, handling, and product storage stability. The ratio of component C) can be set arbitrarily, but usually the total weight of modified rosin, synthetic resin and component (C) includes 20 to 55% by mass of modified rosin, 10 to 55% by mass of synthetic resin, ( C) Each component contains 5 to 50% by mass. With this mass ratio, the core-shell type aqueous biomass emulsion of the present invention contains 13 to 51% by mass of biomass material in the total mass of the modified rosin, the synthetic resin, and the component (C) as the rosin, which is the raw material of the modified rosin. contains

The total amount of components (A) to (C) is preferably 20 to 60% by mass of the core-shell type aqueous biomass emulsion for handling during production, storage, transportation, and use of the product.

The core-shell type aqueous biomass emulsion of the present invention contains surfactants, antifoaming agents, antiseptics, leveling agents, rust inhibitors, lubricants (wax), freeze stabilizers, Various additives such as fillers, other resin varnishes, emulsions, organic solvents, etc. can be added.

When the core-shell type aqueous biomass emulsion of the present invention is used for ink, it is used by adding it as a binder resin to a dispersion in which a pigment is dispersed using a pigment dispersant. In addition, in the case of coating varnish, it can be obtained by adding the various additives described above to the core-shell type aqueous biomass emulsion according to the various physical properties required.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to Examples. However, the present invention is not limited to these examples.

<Number average molecular weight measurement>
The number average molecular weight (Mn) of the modified rosin used in the examples was measured by the GPC method under the following conditions.
Measuring device: High-speed GPC device (HLC-8320GPC: manufactured by Tosoh Corporation)
Column: Two TSKGEL SUPERMULTIPORE-HZ H and TSKGEL SUPERMULTIPORE-HZ M (both manufactured by Tosoh Corporation) are connected together Guard column: TSKguardcolumn SuperMP (HZ)-M (manufactured by Tosoh Corporation)
Eluent: Tetrahydrofuran Flow rate: 0.35 mL/min Column temperature: 40°C
Sample concentration: 0.1%
Standard: TSKgel standard polystyrene (manufactured by Tosoh Corporation)

<Synthesis of modified rosin>
<Synthesis Example 1>
225 g of raw rosin (A5: Mn230, acid value: 180 mgKOH/g) was charged into a reaction vessel equipped with a stirring motor, stirring blades, temperature sensor, reflux condenser, and nitrogen inlet tube. The temperature was raised to After confirming that the raw rosin was sufficiently melted, 56 g of maleic anhydride was added in portions and kept warm for 8 hours. After that, the internal temperature was raised to 215° C., and 56 g of pentaerythritol and 1.5 g of glycerin were added. After the addition, the internal temperature was kept at 200° C., and the reaction was terminated when the acid value reached 150 mgKOH/g to obtain a maleated rosin ester of Mn430. This is designated as modified rosin (A1).

<Synthesis Example 2>
A reaction vessel equipped with a stirring motor, a stirring blade, a temperature sensor, a reflux condenser and a nitrogen inlet tube was charged with 100 g of raw rosin. After confirming that the raw rosin was sufficiently melted, 12 g of maleic anhydride was added in portions and allowed to react for 8 hours to obtain a maleated reinforced rosin having an Mn of 270 and an acid value of 230 mgKOH/g. This is designated as modified rosin (A2).

<Synthesis Example 3>
A fumarated reinforced rosin having an Mn of 270 and an acid value of 190 mgKOH/g was obtained in the same manner as in Synthesis Example 2, except that 8.5 g of fumaric acid was used as the maleic anhydride to be added to the raw rosin. This is designated as modified rosin (A3).

<Synthesis Example 4>
A maleated rosin ester of Mn 4,000 was obtained in the same manner as in Synthesis Example 1, except that the reaction was terminated when the acid value reached 125 mgKOH/g. This is designated as modified rosin (A4).

<Synthesis Example 5>
A maleated rosin ester of Mn 6,000 was obtained in the same manner as in Synthesis Example 1, except that the reaction was terminated when the acid value reached 115 mgKOH/g. This is called modified rosin (A6).

<Synthesis of core-shell type aqueous biomass emulsion>
<Example 1>
A reaction vessel equipped with a stirring motor, a stirring blade, a temperature sensor, a reflux condenser, a dropping funnel, a polymerization initiator addition line and a nitrogen inlet tube was charged with 40 g of modified rosin (A1) and an acid value of 240 mg KOH/g as synthetic resin (B1). 10 g of styrene-acrylic resin VS-1047 (manufactured by Seiko PMC Co., Ltd.) and 100 g of water were charged and stirred. Aqueous ammonia was added thereto in an amount equivalent to 100% of the total acid value of the modified rosin (A1) and the synthetic resin (B1), and the internal temperature was raised to 75° C. to dissolve. On the other hand, in a dropping funnel, 27 g of styrene (hereinafter sometimes abbreviated as St), 19 g of 2-ethylhexyl acrylate (hereinafter sometimes abbreviated as 2EHA), and 4 g of glycidyl methacrylate (hereinafter sometimes abbreviated as GMA) were mixed. A mixed monomer solution was prepared. In another container, 0.4 g of ammonium persulfate as a polymerization initiator was dissolved in 22 g of water and set so that it could be added from the polymerization initiator addition line. After the interior of the reaction vessel was sufficiently purged with nitrogen, the monomer mixture and the polymerization initiator were added into the reaction vessel over 3 hours to obtain a core-shell type aqueous biomass emulsion (E1).

<Examples 2 to 11>
Core-shell emulsions (E2) to (E11) of Examples 2 to 11 were obtained in the same manner as in Example 1, except that the types and amounts of components (A) to (C) were changed as shown in Table 1. rice field.

<Comparative Example 1>
An attempt was made to obtain a core-shell type aqueous biomass emulsion in the same manner as in Example 1, except that instead of the modified rosin (A1) in Example 1, raw rosin (A5: Mn230) was used without modification. After standing still, the emulsion separated and could not be subjected to the next evaluation.

<Comparative Example 2>
An attempt was made to obtain a core-shell type aqueous biomass emulsion in the same manner as in Example 1, except that modified rosin (A6: Mn 6,000) was used instead of modified rosin (A1) in Example 1. However, during emulsion polymerization, The emulsion gelled and could not be used for the next evaluation.

<Comparative Examples 3 to 5>
Emulsions (RE3) to (RE5) of Comparative Examples 3 to 5 were obtained in the same manner as in Example 1 except that the types and amounts of components (A) to (C) were changed as shown in Table 1.

<Comparative Example 6>
A reaction vessel equipped with a stirring motor, a stirring blade, a temperature sensor, a reflux condenser, a dropping funnel, a polymerization initiator addition line and a nitrogen introduction tube was charged with a styrene-acrylic resin VS- having an acid value of 240 mgKOH/g as the synthetic resin (B1). 25 g of 1047 (manufactured by Seiko PMC Co., Ltd.) and 100 g of water were charged and stirred. Aqueous ammonia was added thereto in an amount equivalent to 100% of the total acid value of the modified rosin (A1) and the synthetic resin (B1), and the internal temperature was raised to 75° C. to dissolve. On the other hand, in a dropping funnel, 27 g of styrene (hereinafter sometimes abbreviated as St), 19 g of 2-ethylhexyl acrylate (hereinafter sometimes abbreviated as 2EHA), and 4 g of glycidyl methacrylate (hereinafter sometimes abbreviated as GMA) were mixed. Then, a modified rosin-containing monomer mixture in which the modified rosin (A1) was completely dissolved was prepared. In another container, 0.4 g of ammonium persulfate as a polymerization initiator was dissolved in 22 g of water, and set so that it could be added from the polymerization initiator addition line. After the interior of the reaction vessel is sufficiently purged with nitrogen, the monomer mixture and the polymerization initiator are added to the reaction vessel over 3 hours to form a core-shell type aqueous biomass emulsion (RE6 ).

<Comparative Example 7>
100 g of the maleated rosin ester (A1) obtained in Synthesis Example 1 was added with an aqueous ammonia equivalent to 100% equivalent to the acid value of the maleated rosin ester, heated to an internal temperature of 75° C. and dissolved to obtain a varnish (RE7). got

Table 1 shows the types and amounts of components (A) to (C) used in each example and comparative example, and Table 2 shows the physical properties of the emulsion obtained in each example and comparative example (varnish in comparative example 7). and the rosin content (% by mass) with respect to the total of modified rosin, synthetic resin and component (C). The viscosity here is the emulsion viscosity at 25°C measured with a Brookfield viscometer, and the non-volatile content is 2 g of each emulsion weighed in an aluminum cup, dried at 140°C for 1 hour, and then dried with a desiccant. After cooling to 25° C. in a desiccator containing the emulsion, the mass of the residue was measured, and the mass ratio (%) of non-volatile components in the emulsion was calculated.

(Abbreviations in Table 1)
(B) Component B1: VS-1047 (styrene-acrylic resin, manufactured by Seiko PMC Co., Ltd.), acid value 240 mgKOH/g
B2: US-1243 (styrene-acrylic-maleic acid resin, manufactured by Seiko PMC Co., Ltd.), acid value 190 mgKOH / g
B3: X-310 (acrylic resin, manufactured by Seiko PMC Co., Ltd.), acid value 60 mgKOH / g
B4: X-210 (styrene-maleic acid resin, manufactured by Seiko PMC Co., Ltd.) acid value 190 mg KOH / g
B5: PVA-117 (polyvinyl alcohol, manufactured by Kuraray Co., Ltd.)
B6: Newcoal 2320-SN (polyoxyethylene alkyl ether sulfate, manufactured by Nippon Nyukazai Co., Ltd.)
(C) Component St: Styrene (solubility in water: 0.1 g/100 g water or less)
2EHA: 2-ethylhexyl acrylate (solubility in water: 0.1 g/100 g water or less)
MA: methyl acrylate (solubility in water: 6.0 g/100 g water)
GMA: glycidyl methacrylate (solubility in water: 2.3g/100g water)
NaOH: sodium hydroxide

<Paint film evaluation>
Commercially available coated paper, untreated PET film, and corona discharge-treated PET film were used as substrates, and each emulsion obtained in Examples and Comparative Examples (varnish in Comparative Example 7) was used as a coating liquid on each substrate. , bar coater No. 10 (manufactured by Daiichi Rika Co., Ltd.) and air-dried to obtain a coated product. By visual inspection, the case where a uniform coating film was obtained was rated as good (3), the practical level was acceptable (2) although there was some rubbing and unevenness, and the case where there was overall rubbing and unevenness was rated as unsatisfactory (1). evaluated.

<Adhesion evaluation>
A cellophane tape was attached to each coated product obtained by the above coating and peeled off perpendicularly to the coated surface. When the coated material was not peeled off at all, it was evaluated as good (3).
<Odor>
The odor of each emulsion (varnish in Comparative Example 7) obtained in Examples and Comparative Examples was directly smelled, and the evaluation was made as good (3) when no odor of rosin was felt, and as poor (1) when odor of rosin was felt. .

Table 3 shows the coating film of each sample, the adhesion test evaluation, and the odor results.

The core-shell type aqueous biomass emulsions (E1 to E11) obtained in Examples 1 to 11, which satisfy the conditions of the present invention, exhibited a practical level of adhesion to all substrates, and no rosin odor was felt ( Evaluation Examples 1 to 11). On the other hand, in Comparative Evaluation Examples 1 to 5, which did not satisfy any one of the conditions of the present invention, either the emulsion was not obtained, or the coating film was uneven or the adhesion to the substrate was poor in the coating evaluation. (Comparative Evaluation Examples 1 to 5). Also, the emulsions of Comparative Examples 6 and 7 smelled of rosin (Comparative Evaluation Examples 4 and 5).

From the comparison between Evaluation Example 1 and Evaluation Example 8, and between Evaluation Example 5 and Evaluation Examples 6 and 7, using a styrene-acrylic resin as the component (B) compared to using the other component (B). , the adhesion evaluation was good for all substrates.

From a comparison between Evaluation Example 1 and Evaluation Example 9, when a monomer having a solubility in water at 20° C. of less than 3 g/100 g water is used as the component (C), compared to the case of using the other component (C) A more uniform coating was obtained.

The core-shell type aqueous biomass emulsion provided by the present invention has reduced rosin-specific odor and excellent adhesion to paper and film, and is therefore useful as a raw material for printing ink binders or coating varnishes.

Claims (4)

water, (A) modified rosin alkali salt, (B) at least one water-soluble synthesis selected from the group of styrene-acrylic resin, acrylic resin, styrene-maleic acid resin, and styrene-acrylic-maleic acid resin resin alkali salt, (C) an emulsion polymer of a vinyl group-containing monomer having a solubility in water at 20° C. of less than 3 g/100 g water , wherein the components (A) and (B) are the shell portion; ) component constitutes the core portion, the modified rosin contained in the component (A) has a number average molecular weight of 250 to 5,000, and the modified rosin, the synthetic resin and the modified rosin in the total mass of the component (C) A core-shell type aqueous biomass emulsion characterized by containing 20 to 55% by mass of rosin. The core-shell type aqueous biomass emulsion according to claim 1, wherein the synthetic resin is a styrene-acrylic resin. An aqueous binder resin for printing ink, comprising the core-shell type aqueous biomass emulsion according to claim 1 or 2 . An aqueous coating varnish comprising the core-shell type aqueous biomass emulsion according to claim 1 or 2 .