Aqueous resin emulsion

Abstract

Disclosed is an aqueous resin emulsion obtainable by multi-stage emulsion polymerization of a plurality of polymerizable unsaturated monomers in the presence of a surfactant, polymerizable unsaturated monomers (a) being polymerized in stages other than the last stage, and polymerizable unsaturated monomers (b) being polymerized in the last stage, wherein the surfactant contains a sulfate salt having an allyl group and a polyoxyethylene group, and the aqueous resin emulsion contains a copolymer of specific polymerizable unsaturated monomers (a) and a copolymer of specific polymerizable unsaturated monomers (b).

Description

TECHNICAL FIELD

[0001] The present application relates to an aqueous resin emulsion obtainable by multistage emulsion polymerization, an aqueous resin composition containing the aqueous resin emulsion, and a substrate such as paper and plastic coated with the aqueous resin composition. BACKGROUND

[0002] The aqueous resin emulsion is prepared by emulsion polymerization of a polymerizable unsaturated monomer in the presence of various surfactants. Using the aqueous resin emulsion thus obtained, for example, as a raw material for paints, adhesives, and as a coating agent for paper and plastic, etc.

[0003] Emulsion polymerization is excellent in terms of the environment and safety because a large amount of organic solvent does not need to be used as in solution polymerization, and there is no difficulty in performing slow cooling as in bulk polymerization. But the fact that the mechanical stability of the emulsion can be insufficient because impurities easily enter the aqueous resin emulsion and the emulsion is not easily stably dispersed can be exemplified as a disadvantage of emulsion polymerization.

[0004] Patent Document 1 discloses an aqueous pressure-sensitive adhesive in which two emulsions having different glass transition temperatures, i.e., containing two aqueous resins having different glass transition temperatures, are mixed (see [Claim 1] and Tables 1 to 4 in the Examples). The aqueous pressure-sensitive adhesive of Patent Document 1 exhibits satisfactory curved surface adhesion due to its high tackiness, and is capable of preventing the pressure-sensitive adhesive from adhering to a cutting machine when the pressure-sensitive adhesive product is manufactured by the cutting machine (see Table 3 in

[0141] ).

[0005] Patent Document 2 discloses an aqueous resin prepared by multistage emulsion polymerization of a polymerizable monomer, and a floor polish prepared from the aqueous resin (see

[0019] and Tables 5 to 8 in

[0153] to

[0156] ). The multistage emulsion polymerization of the polymerizable monomer enables improvement in the durability of the aqueous resin emulsion (specifically, water resistance and black heelmark resistance). Thus, the aqueous resin emulsion of Patent Document 2 is suitable as a raw material for a floor polish.

[0006] Bibliographic List

[0007] Patent Document

[0008] [Patent Document 1] JP 2016-117785 A

[0009] [Patent Document 2] JP 2016-98358 A SUMMARY

[0010] PROBLEMS TO BE SOLVED BY THE INVENTION

[0011] As described above, the water-based resin emulsion of Patent Literature 1 is suitable as a raw material for a water-based pressure-sensitive adhesive, and the water-based resin emulsion of Patent Literature 2 is most suitable as a water-based resin for a floor polish. However, in addition to the above-described applications, the water-based resin emulsion is used in various fields. For example, there are applications in which the water-based resin emulsion is directly applied to a substrate such as paper and a film, an inorganic material, and there are applications in which a resin layer formed on a substrate is covered with an emulsion composition to protect the substrate.

[0012] In view of the use of the water-based resin emulsion in various applications, it is desirable that, in addition to the retention property and the water resistance, the water-based resin emulsion has excellent other types of durability (e.g., alcohol resistance, ester-based solvent resistance, plasticizer resistance, etc.) at a higher level.

[0013] The present application was completed in order to solve the above-described problems, and an object of the present application is to provide a water-based resin composition having excellent water resistance, alcohol resistance, ester-based solvent resistance, and plasticizer resistance, which can be applied to various substrates and is capable of protecting a substrate by coating a resin layer previously formed on the substrate; to provide a water-based resin emulsion as a main component of the water-based resin composition; and to provide a substrate coated with the water-based resin composition.

[0014] Solution

[0015] As a result of intensive studies to solve the above-described problems, the present inventors have found that, when a specific polymerizable unsaturated monomer is subjected to a multi-stage emulsion polymerization in the presence of a specific surfactant, the water-based resin emulsion thus obtained has excellent durability (water resistance, alcohol resistance, ester-based solvent resistance, and plasticizer resistance), and a water-based resin composition containing the water-based resin emulsion can be applied to various substrates, and the coated substrate thus obtainable has excellent durability, and thus completed the present application.

[0016] The present application and the preferred embodiments of the present application are as follows:

[0017] 1. A water-based resin emulsion, which is obtainable by subjecting a plurality of polymerizable unsaturated monomers to a multi-stage emulsion polymerization in the presence of a surfactant, a polymerizable unsaturated monomer (a) being polymerized in a stage other than the last stage, and a polymerizable unsaturated monomer (b) being polymerized in the last stage, wherein

[0018] the surfactant comprises a sulfate salt having an allyl group and a polyoxyethylene group,

[0019] the water-based resin emulsion comprises a copolymer of the polymerizable unsaturated monomer (a) and a copolymer of the polymerizable unsaturated monomer (b),

[0020] the copolymer of the polymerizable unsaturated monomer (a) has a lower glass transition temperature than the copolymer of the polymerizable unsaturated monomer (b),

[0021] the polymerizable unsaturated monomer (a) and the polymerizable unsaturated monomer (b) include a (meth)acrylate and a monomer having an alkoxysilyl group and an olefinic double bond, and

[0022] the polymerizable unsaturated monomer (a) includes the monomer (a2) having an alkoxysilyl group and an olefinic double bond in an amount of 0.05 to 1.0 parts by mass per 100 parts by mass of the polymerizable unsaturated monomer (a).

[0023] 2. The aqueous resin emulsion according to 1, wherein the polymerizable unsaturated monomer (a) further includes a monomer having a carboxyl group.

[0024] 3. The aqueous resin emulsion according to 1 or 2, wherein the polymerizable unsaturated monomer (b) includes the monomer (b2) having an alkoxysilyl group and an olefinic double bond in an amount of 0.01 to 1.0 parts by mass per 100 parts by mass of the polymerizable unsaturated monomer (b).

[0025] 4. The aqueous resin emulsion according to any one of 1 to 3, wherein the mass ratio of (b) to (a) ((b) / (a)) is 30 / 70 to 70 / 30.

[0026] 5. An aqueous resin composition including the aqueous resin emulsion according to any one of 1 to 4.

[0027] 6. A substrate coated with the aqueous resin composition according to 5.

[0028] Advantages of the Invention

[0029] The aqueous resin emulsion according to the embodiments of the present invention is obtainable by multi-stage emulsion polymerization of various polymerizable unsaturated monomers in the presence of a surfactant, and when the surfactant includes a sulfate salt having an allyl group and a polyoxyethylene group and the polymerizable unsaturated monomers include a (meth)acrylate, remarkably excellent durability (water resistance, alcohol resistance, solvent resistance, and plasticizer resistance) can be achieved.

[0030] The aqueous resin composition including the aqueous resin emulsion according to the embodiments of the present invention can be coated onto various substrates, and also can protect a layer previously formed on the substrate. The coated substrate has a high level of various durability properties, and can be used for various applications. DETAILED DESCRIPTION

[0031] The aqueous resin emulsion according to the present embodiment is obtainable by subjecting a polymerizable unsaturated monomer to a multi-stage emulsion polymerization in the presence of a specific surfactant.

[0032] <surfactant>

[0033] The surfactant is used to form an emulsion of the aqueous medium and the monomer mixture, and has a hydrophilic group that is easily compatible with water and a lipophilic (hydrophobic) group that is easily compatible with oil in the molecule. When a small amount of the surfactant is dissolved in a solvent, the surfactant significantly reduces the surface tension of the solution, and the polymer solids (dispersoids) can be uniformly dispersed in the aqueous medium.

[0034] The "surfactant" in the present disclosure includes a sulfate salt having an allyl group (2-propenyl group: CH2=CH-CH2-) and a polyoxyethylene group ((OCH2CH2) n ). The presence of the sulfate salt having an allyl group and a polyoxyethylene group allows the aqueous resin emulsion according to the present embodiment to have excellent water resistance.

[0035] Examples of the sulfate salt having an allyl group and a polyoxyethylene group include an ammonium sulfate salt having an allyl group and a polyoxyethylene group, a sodium sulfate salt having an allyl group and a polyoxyethylene group, and a potassium sulfate salt having an allyl group and a polyoxyethylene group.

[0036] Specifically, examples include:

[0037] polyoxyethylene-1-(allyloxymethyl)alkyl ether ammonium sulfate salt, polyoxyethylene-1-(allyloxymethyl)alkyl ether sodium sulfate salt, polyoxyethylene-1-(allyloxymethyl)alkyl ether potassium sulfate salt, α-[1-[(allyloxy)methyl]-2-(nonylphenoxy)ethyl]-ω-polyoxyethylene sulfate ammonium salt, α-[1-[(allyloxy)methyl]-2-(nonylphenoxy)ethyl]-ω-polyoxyethylene sulfate sodium salt, α-[1-[(allyloxy)methyl]-2-(nonylphenoxy)ethyl]-ω-polyoxyethylene sulfate potassium salt, and the like. These sulfate salts can be used alone or in combination.

[0038] The sulfate salt having an allyl group and a polyoxyethylene group according to the present embodiment is preferably an ammonium sulfate salt. That is, polyoxyethylene-1-(allyloxymethyl)alkyl ether ammonium sulfate salt and α-[1-[(allyloxy)methyl]-2-(nonylphenoxy)ethyl]-ω-polyoxyethylene sulfate ammonium salt are preferred, and polyoxyethylene-1-(allyloxymethyl)alkyl ether ammonium sulfate salt is particularly most preferred.

[0039] When the surfactant includes an ammonium sulfate salt having an allyl group and a polyoxyethylene group, the water resistance of the aqueous resin emulsion is further improved.

[0040] Examples of commercially available products of the sulfate salt having an allyl group and a polyoxyethylene group include polyoxyethylene-1-(allyloxymethyl)alkyl ether sulfate ammonium salt ("AQUALON KH-10" (trade name): polyoxyethylene chain length is 10) and ("AQUALON KH-1025" (trade name): 25% aqueous solution of AQUALON KH-10) manufactured by the first industrial co., ltd.; and "Adecaria Soap SR-1025" (trade name) manufactured by Asahi Denka Co., Ltd. as α-[1-[(allyloxy)methyl]-2-(nonylphenoxy)ethyl]-ω-polyoxyethylene sulfate salt.

[0041] "Adecaria Soap SR-1025" (trade name) manufactured by Asahi Denka Co., Ltd. as α-[1-[(allyloxy)methyl]-2-(nonylphenoxy)ethyl]-ω-polyoxyethylene sulfate salt.

[0042] <Polymehzable unsaturated monomer>

[0043] In an embodiment of the present application, "a polymerizable unsaturated monomer" refers to a radical polymerizable monomer having an olefinic double bond.

[0044] In the present specification, "an olefinic double bond" refers to a double bond between carbon atoms which can undergo a polymerization reaction (radical polymerization). Examples of functional groups having an olefinic double bond include a vinyl group (CH2=CH-), a (methyl)allyl group (CH2=CH-CH2- and CH2=C(CH3)-CH2-), a (methyl)acryloyloxy group (CH2=CH-COO- and CH2=C(CH3)-COO-), a (methyl)acryloyloxyalkyl group (CH2=CH-COO-R- and CH2=C(CH3)-COO-R-), and -COO-CH=CH-COO-, and the like.

[0045] In an embodiment of the present application, "a polymerizable unsaturated monomer" includes a (meth)acrylate.

[0046] In the present specification, "(meth)acrylic acid" refers to both of acrylic acid and methacrylic acid, and includes at least one of acrylic acid and methacrylic acid.

[0047] "(Meth)acrylate" refers to an ester of (meth)acrylic acid, i.e., a (meth)acrylate. (Meth)acrylate refers to both of an acrylate and a methacrylate, and includes at least one of an acrylate and a methacrylate. Note that a vinyl ester having a structure in which a vinyl group and an oxygen are bonded to each other, such as vinyl acetate, is not included in the (meth)acrylate described in the present specification.

[0048] Specific examples of the (meth)acrylate include alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, amyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, octyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, stearyl (meth)acrylate, behenyl (meth)acrylate, and the like; and

[0049] hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and the like.

[0050] Such (meth)acrylates can be used alone, or in combination of two or more thereof.

[0051] In the embodiments of the present application, the (meth)acrylate is preferably an alkyl (meth)acrylate. More specifically, it is preferable to include methyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, or cyclohexyl (meth)acrylate, and it is particularly preferable to include at least one selected from n-butyl acrylate and 2-ethylhexyl (meth)acrylate. The alkyl (meth)acrylate includes a (meth)acrylic acid cycloalkyl ester.

[0052] In the mixing of these monomers to form a monomer emulsion and the preparation of a pre-emulsion, and then the final preparation of an aqueous resin emulsion by a multi-stage emulsion polymerization, the glass transition temperature of the pre-emulsion and the aqueous resin emulsion (final product) will be easily controlled, thereby enabling the improvement of the water resistance and the like of the aqueous resin emulsion.

[0053] In the embodiments of the present application, the polymerizable unsaturated monomer can include, in addition to the (meth)acrylate, a "monomer having an alkoxysilyl group and an olefinic double bond" and / or a "monomer having a carboxyl group".

[0054] The monomer having an alkoxysilyl group and an olefinic double bond refers to a compound capable of imparting an alkoxysilyl group to an aqueous resin emulsion obtainable by an emulsion polymerization reaction, and is not particularly limited as long as the aqueous resin emulsion of the embodiments of the present application can be obtained.

[0055] The monomer having an alkoxysilyl group and an olefinic double bond has both an alkoxysilyl group and an olefinic double bond, and the alkoxysilyl group and the olefinic double bond can be bonded through other functional groups such as an ester bond, an amide bond, an alkylene group, and the like.

[0056] Herein, "alkoxysilyl group" refers to a silicon-containing functional group capable of producing a silicon-bonded hydroxyl group (Si-OH) by hydrolysis. Examples of "alkoxysilyl group" include alkoxysilyl groups such as trimethoxysilyl group, triethoxysilyl group, dimethoxysilyl group, dimethoxymethylsilyl group, diethoxysilyl group, monoethoxysilyl group, and monomethoxysilyl group. Trimethoxysilyl group and triethoxysilyl group are particularly preferred. "Ethylenic double bond" is as described above.

[0057] Monomers having an alkoxysilyl group and an ethylenic double bond are not included in the above (meth)acrylates.

[0058] In an embodiment of the present application, when the polymerizable unsaturated monomer includes "monomers having an alkoxysilyl group and an ethylenic double bond", the water-based resin that becomes a dispersion has an alkoxysilyl group. Upon drying of a coated film formed from a water-based resin composition including an emulsion of the water-based resin of the embodiment of the present application, the alkoxysilyl group undergoes dehydration condensation and crosslinking in the coated film to form a crosslinked structure within or between the water-based resins, thereby contributing to improvement in durability (water resistance, alcohol resistance, solvent resistance, plasticizer resistance), etc. of the coated film.

[0059] A compound that is a monomer having an alkoxysilyl group and an ethylenic double bond can be exemplified by the following formula (1):

[0060] R 1 Si(OR 2 )(OR 3 )(OR 4 ) (1)

[0061] wherein, in formula (1), R 1 is a functional group having an ethylenic double bond, R 2 , R 3 , and R 4 are alkyl groups having 1 to 5 carbon atoms, and R 2 , R 3 , and R 4 may be the same as or different from each other.

[0062] Examples of the functional group having an ethylenic double bond for R 1 include vinyl group, (meth)allyl group, (meth)acryloyloxy group, 2- (meth)acryloyloxyethyl group, 2-(meth)acryloyloxypropyl group, 3- (meth)acryloyloxypropyl group, 2-(meth)acryloyloxybutyl group, 3- (meth)acryloyloxybutyl group, and 4-(meth)acryloyloxybutyl group.

[0063] Examples of the alkyl group having 1 to 5 carbon atoms for R 2 , R 3 , and R4 Examples of the alkyl group having 1 to 5 carbon atoms include linear or branched alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, t-butyl, n-pentyl, and the like. Examples of the "monomer having an alkoxysilyl group and an olefinic double bond" include vinyl trialkoxysilane such as vinyl trimethoxysilane, vinyl triethoxysilane, and vinyl tri-n-butoxysilane.

[0064] In particular, 3-(meth)acryloyloxypropyl trimethoxysilane and 3- (meth)acryloyloxypropyl triethoxysilane are preferred, and 3- (meth)acryloyloxypropyl trimethoxysilane is particularly preferred. The use of 3-(meth)acryloyloxypropyl trimethoxysilane can further improve the durability of the aqueous resin emulsion of the embodiments of the present application.

[0065] Such monomers having an alkoxysilyl group and an olefinic double bond can be used alone or in combination.

[0066] In the embodiments of the present application, the polymerizable unsaturated monomer can further include a "monomer having a carboxyl group". Examples of the monomer having a carboxyl group include (meth)acrylic acid. As described above, the (meth)acrylic acid refers to both acrylic acid and methacrylic acid. It is preferred that acrylic acid is used as the (meth)acrylic acid. Unsaturated carboxylic acids such as itaconic acid, fumaric acid, maleic acid, and the like and their monoesters can also be exemplified.

[0067] In the embodiments of the present application, the polymerizable unsaturated monomer can include "other monomers" as long as the target aqueous resin emulsion can be obtained. The other monomers refer to monomers other than the (meth)acrylate, the monomer having an alkoxysilyl group and an olefinic double bond, and the monomer having a carboxyl group.

[0068] Examples of the "other monomers" include, but are not limited to:

[0069] styrene-based monomers such as styrene and styrene sulfonic acid; and

[0070] acrylamides such as (meth)acrylamide and diacetone (meth)acrylamide.

[0071] <Multi-stage emulsion polymerization>

[0072] The aqueous resin emulsion of the embodiments of the present application is obtainable by multi-stage emulsion polymerization of the polymerizable unsaturated monomers in the presence of a surfactant, in which the polymerizable unsaturated monomer (a) is polymerized in stages other than the last stage, and the polymerizable unsaturated monomer (b) is polymerized in the last stage.

[0073] In the present specification, an aqueous resin emulsion is obtainable by emulsion polymerization of polymerizable unsaturated monomers in multiple stages (essentially two stages). Polymerizable unsaturated monomers used during polymerization in stages other than the last stage are defined as (a), while polymerizable unsaturated monomers used during polymerization in the last stage are defined as (b).

[0074] The aqueous resin emulsion ultimately obtainable by the multiple-stage emulsion polymerization can be obtained by polymerizing the polymerizable unsaturated monomers (b) in the presence of a pre-emulsion containing a copolymer obtainable by polymerization of the polymerizable unsaturated monomers (a).

[0075] Thus, the aqueous resin emulsion contains a copolymer of the polymerizable unsaturated monomers (a) and a copolymer of the polymerizable unsaturated monomers (b).

[0076] In an embodiment of the present application, the multiple-stage emulsion polymerization is performed in the presence of a surfactant having a sulfate salt of an allyl group and a polyoxyethylene group. The polymerizable unsaturated monomers (a) preferably contain (al) a (meth)acrylate; more preferably, in addition to (al), (a2) a monomer having an alkoxysilyl group and an olefinic double bond; particularly preferably, in addition to (al) and (a2), (a3) a monomer having a carboxyl group. The polymerizable unsaturated monomers (b) preferably contain (bl) a (meth)acrylate; more preferably, in addition to (bl), (b2) a monomer having an alkoxysilyl group and an olefinic double bond.

[0077] The aqueous resin emulsion obtainable by the multiple-stage emulsion polymerization contains two copolymers: a copolymer based on the polymerizable unsaturated monomers (a) used in stages other than the last stage, and a copolymer based on the polymerizable unsaturated monomers (b) used in the last stage. The two copolymers can have a multilayer (core-shell) structure. The aqueous resin emulsion containing the two copolymers can be coated onto various substrates because it is easy to form a film. Furthermore, the durability (alcohol resistance, ester solvent resistance, and plasticizer resistance) of the aqueous resin emulsion containing the two copolymers obtainable by the multiple-stage emulsion polymerization is further improved.

[0078] When a sulfate salt of an allyl group and a polyoxyethylene group is used as the surfactant, the aqueous resin emulsion of the present application embodiment has remarkably excellent water resistance.

[0079] Thus, the aqueous resin composition of the present application embodiment contains the above-described aqueous resin emulsion, so that the aqueous resin composition has excellent coatability and durability (water resistance, alcohol resistance, ester solvent resistance, and plasticizer resistance), and is easy to coat onto various substrates, and is also suitable as a protective layer for the substrates.

[0080] The polymerizable unsaturated monomer (a) and the polymerizable unsaturated monomer (b) can be the same or different.

[0081] In the embodiment of the present application, the polymerizable unsaturated monomers used in the multi-stage emulsion polymerization include the polymerizable unsaturated monomer (a) used in the stages other than the last stage and the polymerizable unsaturated monomer (b) used in the last stage, and the mass ratio of (b) to (a) ((b) / (a)) is preferably 30 / 70 to 70 / 30, particularly preferably 40 / 60 to 60 / 40.

[0082] When the mass ratio of (b) to (a) is within the above ratio, the aqueous resin composition of the embodiment of the present application is excellent in the balance between coatability and durability (water resistance, alcohol resistance, ester-based solvent resistance, and plasticizer resistance).

[0083] The method of the multi-stage emulsion polymerization in the embodiment of the present application will be described specifically below.

[0084] First, the polymerizable unsaturated monomer (a) is prepared in a container such as a flask. It is preferable that the polymerizable monomer (a) include (al) a (meth)acrylate, (a2) a monomer having an alkoxysilyl group and an olefinic double bond, and (a3) a monomer having a carboxyl group. These monomers are mixed uniformly to prepare a mixture of the polymerizable unsaturated monomer (a).

[0085] To the sulfate salt having an allyl group and a polyoxyethylene group, water (or an aqueous medium) is added to obtain an aqueous solution. To the aqueous solution, the mixture of the polymerizable unsaturated monomer (a) is added to prepare a monomer emulsion (A).

[0086] The polymerizable unsaturated monomer (a) includes, per 100 parts by mass of the polymerizable unsaturated monomer, more preferably 85 to 99 parts by mass, particularly preferably 90 to 98 parts by mass of (al) the (meth)acrylate.

[0087] The polymerizable unsaturated monomer (a) includes, per 100 parts by mass of the polymerizable unsaturated monomer, more preferably 0.05 to 1.0 parts by mass, particularly preferably 0.4 to 0.8 parts by mass of (a2) the monomer having an alkoxysilyl group and an olefinic double bond.

[0088] The polymerizable unsaturated monomer (a) includes, per 100 parts by mass of the polymerizable unsaturated monomer, more preferably 0.5 to 10.0 parts by mass, particularly preferably 2.0 to 6.0 parts by mass of (a3) the monomer having a carboxyl group.

[0089] When the polymerizable unsaturated monomer (a) has the above composition, the durability (water resistance, alcohol resistance, solvent resistance, and plasticizer resistance) of the coated film formed from the aqueous resin composition containing the aqueous resin emulsion of the present embodiment is improved in a well-balanced manner.

[0090] The monomer emulsion (B) is prepared separately from the monomer emulsion (A) in another container. The monomer emulsion (B) can be prepared using the same method as the above method for preparing the monomer emulsion (A).

[0091] Specifically, the polymerizable unsaturated monomer (b) is prepared in another container, such as a flask. Preferably, the polymerizable unsaturated monomer (b) contains (bl) a (meth)acrylate and (b2) a monomer having an alkoxysilyl group and an olefinic double bond. These monomers are mixed uniformly to prepare a mixture of the polymerizable unsaturated monomer (b).

[0092] The mixture of the polymerizable unsaturated monomer (b) is added to an aqueous solution of a sulfate salt having an allyl group and a polyoxyethylene group to obtain a monomer emulsion (B).

[0093] The polymerizable unsaturated monomer (b) includes, per 100 parts by mass of the polymerizable unsaturated monomer (b), more preferably 85 to 99.9 parts by mass, particularly preferably 95 to 99.9 parts by mass of (bl) the (meth)acrylate.

[0094] The polymerizable unsaturated monomer (b) includes, per 100 parts by mass of the polymerizable unsaturated monomer (b), more preferably 0.01 to 1.0 parts by mass, particularly preferably 0.1 to 0.4 parts by mass of (b2) the monomer having an alkoxysilyl group and an olefinic double bond.

[0095] When the polymerizable unsaturated monomer (b) has the above composition, the durability (water resistance, alcohol resistance, solvent resistance, and plasticizer resistance) of the coated film formed from the aqueous resin composition containing the aqueous resin emulsion of the present embodiment is improved in a well-balanced manner.

[0096] Next, water and a sulfate salt having an allyl group and a polyoxyethylene group are fed into a reactor equipped with a stirrer, a thermometer, and the like, and a part of the monomer emulsion (A) and a catalyst are added. While the temperature in the reactor is maintained at a suitable temperature, the remaining monomer emulsion (A) and the catalyst are further added dropwise to prepare a pre-emulsion.

[0097] The monomer emulsion (B) and the catalyst are added dropwise to the pre-emulsion, and then polymerization is performed, and an aqueous resin emulsion as a final product can be synthesized by a multi-stage emulsion polymerization.

[0098] In the present specification, "aqueous medium" means ordinary water such as tap water, distilled water, ion-exchange water, etc., can include a water-soluble or water-dispersible organic solvent which is less reactive with the raw materials (e.g., monomers) of the resin of the present application, such as acetone, ethyl acetate, etc., and can also include a water-soluble or water-dispersible monomer, oligomer, prepolymer and / or resin, and can also include an emulsifier, polymerizable emulsifier, polymerization initiator, chain extender and / or various additives generally used for producing an aqueous or water-soluble resin, as described below.

[0099] The conditions of the polymerization, such as the reaction temperature and reaction time of emulsion polymerization, the kind and concentration of monomers, the stirring rate and the kind and concentration of catalyst, are not particularly limited as long as the aqueous resin emulsion of the embodiments of the present application can be obtained.

[0100] The "catalyst" is preferably a compound which is capable of initiating emulsion polymerization of the polymerizable unsaturated monomers by a small amount of addition, and can be used in the aqueous medium. Examples thereof include ammonium persulfate, sodium persulfate, potassium persulfate, t-butyl peroxybenzoate, 2,2-azobisisobutyronitrile (AIBN) and 2,2-azobis(2-amidinopropane) dihydrochloride and 2,2-azobis(2,4-dimethylvaleronitrile), etc., and ammonium persulfate, sodium persulfate and potassium persulfate are particularly preferred.

[0101] It is preferred that the glass transition temperature of the copolymer of the polymerizable unsaturated monomer (a) is lower than that of the copolymer of the polymerizable unsaturated monomer (b).

[0102] In the embodiments of the present application, the glass transition temperature of the copolymer of the polymerizable unsaturated monomer (a) is preferably -20 to 20°C, more preferably -10 to 20°C, particularly preferably -10 to 15°C. When the glass transition temperature of the copolymer of the polymerizable unsaturated monomer (a) is within the above range, the durability, particularly water resistance, of the aqueous resin emulsion of the embodiments of the present application is further improved.

[0103] In the embodiments of the present application, the glass transition temperature of the copolymer of the polymerizable unsaturated monomer (b) is preferably 10 to 50°C, more preferably 25 to 50°C, particularly preferably 30 to 50°C. When the glass transition temperature of the copolymer of the polymerizable unsaturated monomer (b) is within the above range, the durability, particularly solvent resistance, of the aqueous resin emulsion of the embodiments of the present application is further improved.

[0104] In the present specification, the glass transition temperature of the copolymer of the polymerizable unsaturated monomer (a) can be the glass transition temperature of each homopolymer obtainable by homopolymerization of each polymerizable unsaturated monomer (a) (including (al), (a2) and (a3)), also referred to as "homopolymer T g) to calculate.

[0105] The glass transition temperature can be calculated by taking into account the homopolymer T g and the mixing ratio (mass ratio) of each of (a1), (a2), and (a3) in the polymerizable unsaturated monomer (a).

[0106] Similarly, the glass transition temperature of the copolymer of the polymerizable unsaturated monomer (b) can be calculated from the glass transition temperature of each homopolymer obtained by homopolymerizing each of the polymerizable unsaturated monomers (b) (including (b1) and (b2)) (hereinafter also referred to as "homopolymer T g ").

[0107] Since (a2) and (b2) are used in substantially small amounts, the calculation of the T g does not need to be taken into account in the present specification.

[0108] Specifically, the T g of the copolymer (or resin) of the polymerizable unsaturated monomers can be determined by calculation with the following equation (1). In equation (1), the polymerizable unsaturated monomers are represented as monomers:

[0109] Equation (1):

[0110] 1 / T g = C1 / T g1 + C2 / T g2 +... + C n / T gn

[0111] where, in the calculation equation (1), T g is the theoretical T g of the copolymer (or resin) of the polymerizable unsaturated monomers (mixture), C n is the mass percentage of the nth monomer n in the polymerizable unsaturated monomer mixture, T gn is the homopolymer T g of the nth monomer n, and n is the number of monomers constituting the copolymer and is a positive integer.

[0112] The values mentioned in the literature can be used as the homopolymer T g . Such literature includes, for example, POLYMER HANDBOOK (4th edition; published by John Wiley & Sons, Inc.). As an example, the homopolymer T g of the monomers mentioned in POLYMER HANDBOOK is as shown below.

[0113] Methyl methacrylate ("MMA", T g = 105°C)

[0114] n-butyl acrylate ("n-BA", T g = -54°C)

[0115] 2-ethylhexyl acrylate ("2EHA", T g = -70°C)

[0116] styrene ("St", T g = 100°C)

[0117] acrylic acid ("AA", T g = 106°C)

[0118] methacrylic acid ("MAA", T g = 130°C)

[0119] n-butyl methacrylate ("BMA", T g = 20°C)

[0120] cyclohexyl methacrylate ("CHMA", T g = 83°C)

[0121] In the present specification, in addition to the T g of each homopolymer obtainable by homopolymerizing each of the above-mentioned monomers, the glass transition temperature (T g ) of each homopolymer obtainable by homopolymerizing other monomers can also be applied to formula (1).

[0122] In the embodiments of the present application, the aqueous resin emulsion can be neutralized depending on the properties of the aqueous resin emulsion used as a dispersion. Here, "neutralization" can be performed by adding a basic substance which is usually used for neutralization.

[0123] In the present specification, "basic substance" means a substance which has a pH higher than 7 when dissolved in water. Generally, the form of the basic substance can be a gas, a liquid or a solid, but a water-soluble form in which the basic substance is made soluble in water is preferred because it is easy to handle and control the neutralization reaction. Examples of such "basic substance" include ammonia, alkali metals such as sodium and potassium, and alkaline earth metals such as calcium and magnesium. Aqueous ammonia, an aqueous solution of sodium and an aqueous solution of potassium are preferred.

[0124] The basic substance is added so as to adjust the pH of the aqueous medium containing the aqueous resin to preferably 8.0 or higher, more preferably 8.0 to 10.0, particularly preferably 8.0 to 9.5.

[0125] The aqueous resin emulsion of the embodiments of the present application preferably includes a dispersed substance (or aqueous resin) having an average particle diameter of 0.25 μm or less.

[0126] In an embodiment of the present application, the average particle diameter of the dispersoid (or the aqueous resin) is particularly preferably 0.05 to 0.20 μm. The average particle diameter in the present specification means a particle diameter determined by measuring the particle diameter using a dynamic light scattering method and analyzing using a cumulative amount method using a PAR III (laser particle size analyzer) manufactured by Otsuka Electronics Co., Ltd.

[0127] The aqueous resin composition according to the embodiment of the present application can optionally contain pigments, fillers, rust-preventive agents, thickeners, dispersants, antifoaming agents, preservatives, film-forming aids, and the like known to those skilled in the art, as long as the aqueous resin composition contains the aqueous resin emulsion according to the embodiment of the present application.

[0128] The pigment is not particularly limited as long as it is generally used as a pigment. The pigment is generally classified into organic pigments and inorganic pigments.

[0129] Examples of the organic pigment include insoluble azo pigments such as fast yellow, fast yellow, fast orange, and naphthol red; phthalocyanine pigments such as phthalocyanine copper; dye lakes such as fast scarlet lake, tannin lake, and katanol; isoindolino-based pigments such as isoindolino yellow-green and isoindolino yellow-red; quinacridone-based pigments; and perylene-based pigments such as perylene scarlet and perylene purple, and the like.

[0130] Examples of the inorganic pigment include carbon black, white lead, red lead, chrome yellow, vermilion, ultramarine, cobalt oxide, titanium dioxide, titanium yellow, strontium chromate, molybdenum red, molybdenum white, iron black, lithopone, malachite green, guillet green, cobalt blue, and the like.

[0131] The filler refers to a substance added for the purpose of improving performance and reducing cost, and is not particularly limited as long as it is generally used as a filler. Specific examples thereof include calcium carbonate, magnesium carbonate, silica, talc, clay, alumina, and the like.

[0132] The rust-preventive agent refers to a substance added to a material for the purpose of suppressing corrosion of the material, and is not particularly limited as long as it is generally used as a rust-preventive agent. Examples thereof include red lead, white lead, plumbous lead, white lead basic sulfate, white lead basic chromate, calcium plumbate, zinc chromate, cyanamide plumbate, sub-powder, dichloromate, barium chromate, sodium nitrite, dicyclohexyl ammonium nitrile, cyclohexylamine carbonate, rust-preventive oil, and the like.

[0133] The thickening agent is not particularly limited as long as it is generally used as a thickening agent. Examples thereof include a modified acrylic polymer as a basic thickening type thickening agent, and a urethane-modified polyether and a polyether as an associative type thickening agent. Examples of the basic thickening type thickening agent include hydroxyethyl cellulose (SP600 (trade name) manufactured by Daicel Chemical Industries, Inc.), SN thickener 615 (trade name) manufactured by SAN NOPCO LIMITED, ASE60 (trade name) manufactured by R&H Corporation, KA10K (trade name) manufactured by Henkel Japan Ltd., and the like. Examples of the associative type thickening agent include SN812 (trade name) manufactured by SAN NOPCO LIMITED, RM8W (trade name) manufactured by R&H Corporation, UH752 (trade name) manufactured by ADEKA Corporation, and the like.

[0134] The dispersing agent is not particularly limited as long as it is generally used as a dispersing agent. Examples thereof include potassium tripolyphosphate manufactured by Taihei Chemical Industry Co., Ltd., Primal 850 (trade name) manufactured by Rohm & Haas, DEMOL EP (trade name) manufactured by Kao Corporation, Discoat N-14 (trade name) manufactured by DKS International, OROTAN 165A (trade name) manufactured by R&H Corporation, and SN DISPERSANT 5020 (trade name) manufactured by SAN NOPCO LIMITED.

[0135] The defoaming agent is not particularly limited as long as it is used as a defoaming agent. Examples thereof include hydrophobic silica, and metal soap-based, amide-based, modified silicone-based, silicone compound-based, polyether-based, emulsion-based, and powder-based defoaming agents. Examples thereof include NOPCO S NDeformer 777 (trade name) and SN Deformer VL (trade name) manufactured by SAN NOPCO LIMITED as hydrophobic silica; NOPCO NXZ (trade name) manufactured by SAN NOPCO LIMITED as a metal soap-based defoaming agent; NOPCO 267-A (trade name) manufactured by SAN NOPCO LIMITED as an amide-based defoaming agent; Silicone KM80 (trade name) manufactured by SHIN-ETU CHEMICAL CO., LTD. as a modified silicone-based defoaming agent; SN Deformer 121N (trade name) manufactured by SAN NOPCO LIMITED as a silicone compound-based defoaming agent; SN Deformer PC (trade name) manufactured by SAN NOPCO LIMITED as a polyether-based defoaming agent; NOPCO KF-99 (trade name) manufactured by SAN NOPCO LIMITED as an emulsion-based defoaming agent; SN Deformer 14-HP (trade name) manufactured by SAN NOPCO LIMITED as a powder-based defoaming agent, and the like.

[0136] Examples of the preservative include ACTICIDE LG (trade name) and ACTICIDE MBS (trade name) manufactured by THOR Japan Co.

[0137] The film-forming aid is not particularly limited as long as it is generally used as a film-forming aid. Examples thereof include 2,2,4-trimethylpentanediol-1,3-monoisobutyrate (CS-12 (trade name) manufactured by Chisso Corporation), 2,2,4-trimethylpentanediol-1,3-diisobutyrate (CS-16 (trade name) manufactured by Chisso Corporation), benzyl alcohol, butyl glycol, 2-ethylhexyl glycol, and phenylpropanediol, and dibutyl glycol;

[0138] Organic esters of polyhydric alcohol monoalkyl ethers, such as dipropylene glycol mono-n-butyl ether, trypropylene monoglycol n-butyl ether, ethylene glycol monoethyl ether, ethylene glycol mono-n-butyl ether, and diethylene glycol mono-n-butyl ether; 3-ethoxypropionate, 3-methoxy-3-methylbutyl acetate, benzoate, and adipic acid-based polyesters, and the like.

[0139] The aqueous resin composition of the present embodiment can be applied to various general substrates such as metals, wood, plastics, inorganic building materials, and the like, and is capable of coating and protecting a resin layer formed on the substrate.

[0140] For example, a resin is applied to a plastic film as a carrier of a heat-sensitive recording medium, and dried to form a heat-sensitive recording layer, and the aqueous resin composition of the present embodiment is applied to the layer to form a protective layer.

[0141] As described above, the dispersant contained in the aqueous resin emulsion of the present embodiment has an average particle diameter of 0.25 μm or less, so that the aqueous resin composition of the present embodiment penetrates into wood very well. The aqueous resin composition of the present embodiment penetrates into wood, and does not remain on the surface of the wood in large amounts, so that the appearance of the wood is improved, and the aqueous resin that has penetrated into the wood can prevent the wood from rotting from the inside of the wood.

[0142] Examples

[0143] Embodiments of the present application will be described in detail below, but these embodiments are only one embodiment of the present application, and the present application is not limited by these embodiments.

[0144] Each of the aqueous emulsions according to the embodiments was prepared from a monomer emulsion (A) and a monomer emulsion (B). The polymerizable unsaturated monomers used to prepare (A) and (B), surfactants, and the like are described below.

[0145] Homopolymer T of polymerizable unsaturated monomer g is the value calculated by the aforementioned theoretical formula, and T of the copolymer of the polymerizable unsaturated monomer (a) and the copolymer of the polymerizable unsaturated monomer (b) g is the value calculated by the aforementioned theoretical formula.

[0146] <polymerizable unsaturated monomer>

[0147] Methyl methacrylate (methyl methacrylate, hereinafter referred to as "MMA" (manufactured by FUJIFILM Wako Pure Chemical Corporation, T of homopolymer g = 105°C)

[0148] 2-Ethylhexyl acrylate (2-ethylhexyl acrylate, hereinafter referred to as "2EHA" (manufactured by FUJIFILM Wako Pure Chemical Corporation, T of homopolymer g = -70°C)

[0149] n-Butyl acrylate (n-Butyl acrylate, hereinafter referred to as "n-BA") (manufactured by FUJIFILM Wako Pure Chemical Corporation, Tg of homopolymer = -54°C) g = -54°C)

[0150] n-Butyl methacrylate (n-Butyl methacrylate, hereinafter referred to as "n-BMA") (manufactured by FUJIFILM Wako Pure Chemical Corporation, Tg of homopolymer = 20°C) g = 20°C)

[0151] Cyclohexyl methacrylate (Cyclohexyl methacrylate, hereinafter referred to as "CHMA") (manufactured by FUJIFILM Wako Pure Chemical Corporation, Tg of homopolymer = 83°C) g = 83°C)

[0152] 3-Methacryloyloxypropyl trimethoxysilane (manufactured by FUJIFILM Wako Pure Chemical Corporation)

[0153] Acrylic acid (hereinafter referred to as "AA") (manufactured by FUJIFILM Wako Pure Chemical Corporation, Tg of homopolymer = 106°C) g = 106°C)

[0154] Styrene (hereinafter referred to as "St") (manufactured by FUJIFILM Wako Pure Chemical Corporation, Tg of homopolymer = 100°C) g = 100°C)

[0155] <Surfactant>

[0156] Polyoxyethylene-1-(allyloxymethyl) alkyl ether sulfate ammonium salt (Aqualon KH10 manufactured by the First Industrial Co., Ltd.) (hereinafter also referred to as "S1"), polyoxyethylene styryl phenyl ether (EMULGEN A-500 manufactured by Kao Corporation) (hereinafter also referred to as "S2")

[0157] <Example 1>

[0158] A monomer emulsion was prepared from a plurality of polymerizable unsaturated monomers, and then a pre-emulsion was prepared from the monomer emulsion, and an aqueous resin emulsion was synthesized from the pre-emulsion. The specific process was as follows.

[0159] (Preparation of monomer emulsion (A))

[0160] As shown in Table 1, 5 parts by mass of (al-1) MMA, 23 parts by mass of (al-3) BA, 10 parts by mass of (al-4) BMA, 10 parts by mass of (al-5) CHMA, 2 parts by mass of (a3) AA, and 0.3 parts by mass of (a2) 3-methacryloxypropyltrimethoxysilane were uniformly mixed to prepare a polymerizable unsaturated monomer (a) solution (50.3 parts by mass).

[0161] To a solution prepared by uniformly mixing 14 parts by mass of water and 0.1 parts by mass of (S1) polyoxyethylene-1-(allyloxymethyl) alkyl ether sulfate ammonium salt, the above polymerizable unsaturated monomer (a) solution was added, and then the mixed solution was stirred by a stirrer to obtain a monomer emulsion (A).

[0162] (Preparation of monomer emulsion (B))

[0163] The monomer emulsion (B) was prepared separately from the monomer emulsion (A). The preparation is shown below. As shown in Table 1, 16.6 parts by mass of (bl-1) MMA, 13 parts by mass of (bl-3) BA, 10 parts by mass of (bl-4) BMA, 10 parts by mass of (bl-5) CHMA, and 0.1 parts by mass of (b2) 3-methacryloxypropyltrimethoxysilane were uniformly mixed to prepare a polymerizable unsaturated monomer (b) solution.

[0164] To a solution prepared by uniformly mixing 14 parts by mass of water and 0.1 parts by mass of (S1) polyoxyethylene-1-(allyloxymethyl) alkyl ether sulfate ammonium salt, the above polymerizable unsaturated monomer (b) solution was added, and then the mixed solution was stirred by a stirrer to obtain a monomer emulsion (B).

[0165] (Synthesis of pre-emulsion)

[0166] 78 parts by mass of water and 1.25 parts by mass of (S1) polyoxyethylene-1-(allyloxymethyl) alkyl ether sulfate ammonium salt were fed into a reactor equipped with a stirrer, a capacitor, and a thermometer, and after replacing the inside of the system with nitrogen, the feed solution was heated to 80°C.

[0167] Subsequently, to the feed solution, 1 mass% aqueous solution of 2 parts by mass of sodium persulfate (hereinafter also referred to as "SPS") and the monomer emulsion (A) (corresponding to 10.1 parts by mass of a part of the polymerizable unsaturated monomer (a), while the entire monomer emulsion (A) contains 50.3 parts by mass of the polymerizable unsaturated monomer (a)) were added.

[0168] After an additional 10 minutes, while maintaining the temperature in the reactor at 80°C, the remaining monomer emulsion (A) (corresponding to 40.2 parts by mass of the portion of the polymerizable unsaturated monomer (a)) and 4 parts by mass of a 1% aqueous solution of SPS as a polymerization catalyst were simultaneously added dropwise over 2 hours to obtain a pre-emulsion (an aqueous resin emulsion based on the polymerizable unsaturated monomer (a)).

[0169] (Synthesis of the aqueous resin emulsion)

[0170] After the completion of the dropwise addition, the temperature in the reactor was maintained at 80°C for 30 minutes, and then the above monomer emulsion (B) (containing 49.7 parts by mass of the unsaturated polymerizable monomer (b)) and 4 parts by mass of a 1% aqueous solution of SPS were simultaneously added dropwise over 2 hours, respectively, to obtain an aqueous resin emulsion.

[0171] The pH of the aqueous resin emulsion thus obtained was adjusted to 8.0 with aqueous ammonia. With respect to the aqueous resin emulsion, the copolymer of the polymerizable unsaturated monomer (a) had a glass transition temperature of -3.8°C, the copolymer of the polymerizable unsaturated monomer (b) had a glass transition temperature of 26.7°C, and the aqueous resin emulsion had a solid concentration of 45% by mass. The solid content was the mass percentage of the remaining portion of the aqueous resin emulsion after drying in an oven at 105°C for 3 hours with respect to the mass of the aqueous resin emulsion before drying.

[0172] <Examples 2 to 5>

[0173] The monomer emulsion and the aqueous resin emulsion were also synthesized in the same manner as in Example 1 using the raw material monomers as shown in Table 1.

[0174] The aqueous resin emulsions of the examples and comparative examples were evaluated by the following method.

[0175] <Water resistance>

[0176] Each of the aqueous resin emulsions finally obtained in the examples and comparative examples was applied to a glass plate using a 5-mil applicator, and immediately dried in a dryer at 105°C to prepare a resin film.

[0177] The film thus obtained was immersed in warm water at 50°C, and its state was confirmed after 24 hours. The evaluation criteria were as follows.

[0178] Coated film is transparent A: by level

[0179] Coated film is thin and hazy, but adheres to the glass plate B: by level

[0180] Coated film is hazy or peels off from the glass plate C: failure level

[0181] <Alcohol resistance>

[0182] Each of the respective aqueous resin emulsions finally obtained in the examples and comparative examples was applied to a thermal recording paper (SD standard thermal paper for word processing manufactured by KOKUYO Co., Ltd.) using a bar coater, and immediately dried in a dryer at 60°C for 5 minutes to obtain a coated paper. One drop of isopropyl alcohol was dropped onto the coated paper and its state was confirmed. The evaluation criteria were as follows.

[0183] No discoloration of thermal paper A: pass level

[0184] Slight discoloration of thermal paper B: pass level

[0185] Blackening of thermal paper C: fail level

[0186] <Ester-based solvent resistance>

[0187] The ester-based solvent resistance was evaluated using the same method as described in the alcohol resistance test except that isopropyl alcohol used in the alcohol resistance evaluation was changed to ethyl acetate. The evaluation criteria were as follows.

[0188] No discoloration of thermal paper A: pass level

[0189] Slight discoloration of thermal paper B: pass level

[0190] Blackening of thermal paper C: fail level

[0191] <Plasticizer resistance>

[0192] The plasticizer resistance was evaluated using the same method as described in the alcohol resistance test except that isopropyl alcohol used in the alcohol resistance evaluation was changed to acetyl tributyl citrate. The evaluation criteria were as follows.

[0193] No discoloration of thermal paper A: pass level

[0194] Slight discoloration of thermal paper B: pass level

[0195] Blackening of thermal paper C: fail level

[0196] [Table 1]

[0197]

[0198] As shown in Table 1, the aqueous resin emulsions of the examples were obtained by multi-stage emulsion polymerization by specific polymerizable unsaturated monomers in the presence of a sulfate ester salt having an allyl group and a polyoxyethylene group as a surfactant, and were excellent in all properties of water resistance, alcohol resistance, ester-based solvent resistance, and plasticizer resistance, and could be coated onto both a glass plate and a thermal recording paper.

[0199] With regard to the aqueous resin emulsion of Comparative Example 1, a sulfated salt having an allyl group and a polyoxyethylene group was not used as a surfactant, but a surfactant (polyoxyethylene styryl phenyl ether) having no sulfated salt was used. Thus, the aqueous resin emulsion of Comparative Example 1 was inferior in all properties of water resistance, alcohol resistance, ester group solvent resistance, and plasticizer resistance.

[0200] With regard to the aqueous resin emulsion of Comparative Example 2, although a sulfated salt having an allyl group and a polyoxyethylene group was used as a surfactant, the aqueous resin emulsion was synthesized by a conventional emulsion polymerization (single-stage polymerization) instead of a multi-stage emulsion polymerization. Thus, the aqueous resin emulsion of Comparative Example 2 contained only one resin, and was excellent in water resistance, but was inferior in other durability properties (alcohol resistance, ester group solvent resistance, and plasticizer resistance).

[0201] As described above, it has been determined that the aqueous resin emulsion of the present embodiment has excellent water resistance, alcohol resistance, ester group solvent resistance, and plasticizer resistance, and has a good balance of durability.

[0202] Industrial applicability

[0203] The present application can provide an aqueous resin emulsion, which can be used in various fields, such as laminated materials, wood materials, paper-based substrates, plastic films, resin layers, and the like.

[0204] An aqueous resin composition containing the aqueous resin emulsion is suitable for use in the production of sanitary materials, building materials, laminated films, packaging materials, electronic materials, heat-sensitive recording media, and the like.

[0205] Cross-reference to related applications

[0206] This application is based on Japanese Patent Application No. 2019-224681 filed in Japan on December 12, 2019, the content of which is incorporated herein by reference in its entirety. The priority application is based on Japanese Patent Application No. 2019-224681 filed in Japan on December 12, 2019, the content of which is incorporated herein by reference in its entirety.

Claims

1. An aqueous resin emulsion obtained by multi-stage emulsion polymerization of a plurality of polymerizable unsaturated monomers in the presence of a surfactant, polymerizable unsaturated monomers (a) being polymerized in stages other than the last stage, and polymerizable unsaturated monomers (b) being polymerized in the last stage, wherein, the surfactant comprises a sulfate salt having an allyl group and a polyoxyethylene group, the aqueous resin emulsion comprises a copolymer of the polymerizable unsaturated monomers (a) and a copolymer of the polymerizable unsaturated monomers (b), the copolymer of the polymerizable unsaturated monomers (a) has a lower glass transition temperature than the copolymer of the polymerizable unsaturated monomers (b), the glass transition temperature of the copolymer of the polymerizable unsaturated monomers (a) is -20 to 15°C, and the glass transition temperature of the copolymer of the polymerizable unsaturated monomers (b) is 10 to 50°C, the polymerizable unsaturated monomers (a) consist of, based on 100 parts by mass of the polymerizable unsaturated monomers (a) and (b): (al) 5 parts by mass of methyl methacrylate, 23 parts by mass of butyl acrylate, 10 parts by mass of n-butyl methacrylate, and 10 parts by mass of cyclohexyl methacrylate, (a2) 0.30 parts by mass of 3-methacryloyloxypropyltrimethoxysilane, and (a3) 2 parts by mass of an acrylic monomer; and the polymerizable unsaturated monomers (b) consist of, based on 100 parts by mass of the polymerizable unsaturated monomers (a) and (b): (bl) 16.6 parts by mass of methyl methacrylate, 13 parts by mass of butyl acrylate, 10 parts by mass of n-butyl methacrylate, and 10 parts by mass of cyclohexyl methacrylate, (b2) 0.10 parts by mass of 3-methacryloyloxypropyltrimethoxysilane; or the polymerizable unsaturated monomers (a) consist of, based on 100 parts by mass of the polymerizable unsaturated monomers (a) and (b): (al) 18 parts by mass of methyl methacrylate, 20 parts by mass of 2-ethylhexyl acrylate, 5 parts by mass of n-butyl methacrylate, and 5 parts by mass of cyclohexyl methacrylate, (a2) 0.50 parts by mass of 3-methacryloyloxypropyltrimethoxysilane, and (a3) 2 parts by mass of an acrylic monomer; and the polymerizable unsaturated monomers (b) consist of, based on 100 parts by mass of the polymerizable unsaturated monomers (a) and (b): (bl) 22 parts by mass of methyl methacrylate, 12.2 parts by mass of 2-ethylhexyl acrylate, 10 parts by mass of n-butyl methacrylate, and 5 parts by mass of cyclohexyl methacrylate, (b2) 0.30 parts by mass of 3-methacryloyloxypropyltrimethoxysilane; or the polymerizable unsaturated monomers (a) consist of, based on 100 parts by mass of the polymerizable unsaturated monomers (a) and (b): (al) 15 parts by mass of methyl methacrylate, 23.6 parts by mass of 2-ethylhexyl acrylate, 5 parts by mass of n-butyl methacrylate, and 5 parts by mass of cyclohexyl methacrylate, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (a2) 0.30 parts by mass of 3-methacryloxypropyltrimethoxysilane, and (a3) 2 parts by mass of an acrylic monomer; and the polymerizable unsaturated monomers (b) consist of, based on 100 parts by mass of the polymerizable unsaturated monomers (a) and (b): (b1) 23.7 parts by mass of methyl methacrylate, 15.3 parts by mass of butyl acrylate, 5 parts by mass of n-butyl methacrylate, and 5 parts by mass of cyclohexyl methacrylate, (b2) 0.10 parts by mass of 3-methacryloxypropyltrimethoxysilane.

2. An aqueous resin composition, the composition comprising the aqueous resin emulsion according to claim 1.

3. A substrate coated with the aqueous resin composition according to claim 2.

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