JP2018104620A - Aqueous resin dispersion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aqueous resin dispersion that makes it possible to conveniently obtain excellent adhesion even to a polyolefin base material such as a polypropylene base material, and can also reduce the energy consumption.SOLUTION: The present invention provides an aqueous resin dispersion in which: in an aqueous medium, dispersed are an olefin polymer (A), and a polymer (B) containing a constitutional unit derived from a radical-polymerizable monomer (b1) containing a reactive functional group excluding a carboxyl group and a hydroxyl group, such as a radical-polymerizable monomer having an epoxy group.SELECTED DRAWING: None

Description

  The present invention relates to an aqueous resin dispersion.

  Polyolefins such as propylene polymers and propylene-α-olefin copolymers are inexpensive and are used in a wide range of fields because of their excellent mechanical properties, heat resistance, chemical resistance, water resistance, and the like. However, since polyolefin does not have a polar group in its molecule and has low polarity, it is often difficult to paint or adhere to a polyolefin substrate.

  As a method for modifying the surface of a polyolefin substrate, a method of chemically treating with a chemical or the like, a method of oxidizing the substrate surface by corona discharge treatment, plasma treatment, flame treatment or the like are known. However, these methods require not only a special apparatus but also an effect of improving paintability and adhesiveness.

  As a method for modifying the surface of a polyolefin substrate, a modified polyolefin or a graft copolymer in which a hydrophilic polymer is grafted to an olefin polymer is used as a surface treatment agent, an adhesive, or a paint on the surface of the substrate. A method of applying an aqueous resin dispersion containing the same is also known. As the modified polyolefin, chlorinated polypropylene, acid-modified propylene-α-olefin copolymer, acid-modified chlorinated polypropylene, or the like is used.

  In addition, in order to improve the performance and storage stability of the aqueous resin dispersion, a modified polyolefin or graft copolymer may be combined with a polymer obtained by polymerizing a radical polymerizable monomer. Proposed. Examples thereof include aqueous resin dispersions obtained by emulsion polymerization of radically polymerizable monomers in the presence of modified polyolefins and graft copolymers (Patent Documents 1 to 5).

JP 2011-46777 A JP2013-133417A JP 2006-36920 A JP 2004-91559 A JP 2002-308921 A

  However, even if the aqueous resin dispersions of Patent Documents 1 to 5 are used, it is difficult to obtain a sufficient improvement effect on the adhesion to the polyolefin substrate, and in order to obtain excellent adhesion, baking at high temperature is essential and energy consumption The amount increases. In particular, it is difficult to obtain excellent adhesion to a polypropylene substrate.

  An object of the present invention is to provide an aqueous resin dispersion that can easily and excellently adhere to a polyolefin substrate such as a polypropylene substrate and can reduce energy consumption.

The present invention has the following configuration.
[1] An olefin polymer (A) and a polymer (B) containing a structural unit derived from a radical polymerizable monomer (b1) containing a reactive functional group excluding a carboxyl group and a hydroxyl group are aqueous. An aqueous resin dispersion dispersed in a medium.
[2] The aqueous resin dispersion according to [1], wherein the radical polymerizable monomer (b1) is a radical polymerizable monomer having an epoxy group.
[3] The aqueous resin dispersion according to [1] or [2], wherein the olefin polymer (A) does not contain a chlorine atom.

  By using the aqueous resin dispersion of the present invention, excellent adhesiveness can be easily obtained even for polyolefin substrates such as polypropylene substrates, and energy consumption can be reduced.

  The aqueous resin dispersion of the present invention comprises an olefin polymer (A) and a polymer containing a structural unit derived from a radical polymerizable monomer (b1) containing a reactive functional group excluding a carboxyl group and a hydroxyl group ( B) is an aqueous resin dispersion dispersed in an aqueous medium.

<Olefin polymer (A)>
The olefin polymer (A) means a polymer containing 50 mol% or more of olefin-derived structural units with respect to all the structural units. The olefin polymer (A) may be a homopolymer or a copolymer.

  The olefin polymer (A) is preferably a propylene polymer containing a propylene-derived structural unit from the viewpoint of excellent adhesion to a polypropylene substrate.

The content of propylene-derived structural units in the propylene-based polymer is preferably 50 mol% or more, more preferably 60 mol% or more, and even more preferably 70 mol% or more with respect to all the structural units.
The melting point (Tm) of the propylene-based polymer is preferably 125 ° C. or lower, more preferably 100 ° C. or lower, and further preferably 90 ° C. or lower. The melting point of the propylene polymer is preferably 60 ° C. or higher.

As the olefin polymer (A), those having a small number of chlorine atoms are preferable from the viewpoint of excellent weather resistance, and a non-chlorinated olefin polymer containing no chlorine atoms is more preferable.
Examples of the olefin polymer (A) include an olefin polymer (A1) having no reactive group (hereinafter also referred to as “polymer (A1)”), and a modified olefin polymer having a reactive group ( A2) (hereinafter also referred to as “polymer (A2)”) and the like, and the polymer (A2) is preferred.

(Polymer (A1))
The polymer (A1) is not particularly limited, and various known olefin homopolymers and olefin copolymers can be used. Specifically, the following polyolefin is mentioned, for example.
A homopolymer of ethylene or propylene; a copolymer of ethylene and propylene; a monomer copolymerizable with at least one of ethylene and propylene and ethylene and propylene (for example, butene-1, pentene-1, hexene-1, A copolymer with α-olefin having 4 or more carbon atoms such as heptene-1, octene-1, cyclopentene, cyclohexene, norbornene); from two or more selected from the group consisting of the α-olefin having 4 or more carbon atoms A copolymer of an α-olefin having 2 or more carbon atoms and a non-aromatic monomer other than an α-olefin such as vinyl acetate, acrylic acid ester or methacrylic acid ester; having 2 or more carbon atoms Copolymer of α-olefin and aromatic monomer such as aromatic vinyl monomer or hydrogenated product thereof; Conjugated diene block copolymer Body or hydrogenated product thereof. The α-olefin having 2 or more carbon atoms is preferably an α-olefin having 2 to 4 carbon atoms. In addition, as a polymer (A1), you may use the chlorinated polyolefin which chlorinated the above-mentioned polyolefin.
In addition, when it is simply referred to as “copolymer”, it may be a random copolymer or a block copolymer.

  The degree of chlorination of the chlorinated polyolefin is usually 5% by mass or more, preferably 10% by mass or more. Moreover, the chlorination degree of chlorinated polyolefin is 40 mass% or less normally, Preferably it is 30 mass% or less.

Specific examples of the polymer (A1) include polyethylene, polypropylene, ethylene-butene copolymer, ethylene-propylene copolymer, propylene-butene copolymer, propylene-hexene copolymer, chlorinated polyethylene, and chlorinated polypropylene. , Chlorinated ethylene-propylene copolymer, chlorinated propylene-butene copolymer, ethylene-vinyl acetate copolymer, hydrogenated product of styrene-butadiene-styrene block copolymer (SEBS), styrene-isoprene-styrene block Examples thereof include a hydrogenated copolymer (SEPS). These polymers (A1) may be used individually by 1 type, and may be used in combination of 2 or more type.
The polymer (A1) may be linear or branched.

  The polymer (A1) preferably has few chlorine atoms, and more preferably does not contain chlorine atoms. As the polymer (A1), a propylene homopolymer or a copolymer of propylene and an α-olefin other than propylene is preferable, and a propylene homopolymer, an ethylene-propylene copolymer, and a propylene-butene copolymer are preferable. More preferred.

  As the polymer (A1), a propylene-based polymer containing a propylene-derived structural unit is preferable. The content of propylene-derived structural units in the propylene-based polymer is preferably 50 mol% or more, more preferably 60 mol% or more, and even more preferably 70 mol% or more with respect to all the structural units. There exists a tendency for the adhesiveness to a polypropylene base material to increase, so that the content rate of structural units other than propylene is high.

The weight average molecular weight (Mw) of the polymer (A1) is preferably 5,000 to 500,000. The lower limit of Mw of the polymer (A1) is more preferably 10,000, further preferably 20,000, and particularly preferably 30,000. As for the upper limit of Mw of a polymer (A1), 300,000 is more preferable. If Mw of a polymer (A1) is 5,000 or more, the stickiness degree of a coating film will become small and there exists a tendency for the adhesiveness to a base material to increase. If the Mw of the polymer (A1) is 500,000 or less, the viscosity of the aqueous powdered resin dispersion is further lowered, and thus the aqueous powdered resin dispersion tends to be easily prepared.
In addition, Mw is the value converted into the calibration curve obtained by measuring each polymer with a known molecular weight using GPC (Gel Permeation Chromatography). GPC measurement is performed by a conventionally known method using a commercially available apparatus using orthodichlorobenzene or the like as a solvent.

The melting point (Tm) of the polymer (A1) is preferably 125 ° C. or lower. If the melting point of the polymer (A1) is 125 ° C. or lower, it is preferable because a high temperature is not required for drying and baking after application of the aqueous resin dispersion. The upper limit value of the melting point of the polymer (A1) is more preferably 100 ° C, further preferably 90 ° C.
The melting point of the polymer (A1) is preferably 60 ° C. or higher. When the melting point of the polymer (A1) is 60 ° C. or higher, the polymer (A1) is less likely to be sticky, and handling is easy when the aqueous resin dispersion is used as a paint.

  The manufacturing method of a polymer (A1) is not specifically limited, For example, radical polymerization, cationic polymerization, anionic polymerization, coordination polymerization etc. are mentioned. These may be living polymerisations.

In the case of coordination polymerization, for example, a method of polymerizing with a Ziegler-Natta catalyst or a method of polymerizing with a single site catalyst can be mentioned, and a method of polymerizing with a single site catalyst is preferred. This is because the single-site catalyst can sharpen the molecular weight distribution and stereoregularity distribution by the ligand design.
As the single site catalyst, for example, a metallocene catalyst or a Brookhart catalyst can be used. As the metallocene catalyst, those having a symmetric type such as a C1 symmetric type, a C2 symmetric type, a C2V symmetric type, and a CS symmetric type are known. In the present invention, an appropriate symmetric metallocene catalyst may be selected and used according to the stereoregularity of the target olefin polymer.

  The polymerization may be in any form such as solution polymerization, slurry polymerization, bulk polymerization, and gas phase polymerization. In the case of solution polymerization or slurry polymerization, examples of the solvent include aromatic hydrocarbons such as toluene and xylene; aliphatic hydrocarbons such as hexane, heptane and octane; alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; Examples include hydrogen; esters; ketones; ethers and the like. Among these, aromatic hydrocarbons, aliphatic hydrocarbons, and alicyclic hydrocarbons are preferable, and toluene, xylene, heptane, and cyclohexane are more preferable. These solvent may be used individually by 1 type, and may be used in combination of 2 or more type.

(Polymer (A2))
The polymer (A2) is a modified olefin polymer having a reactive group. Examples of the reactive group include a carboxyl group and its anhydride, an amino group, an epoxy group, an isocyanato group, a sulfonyl group, and a hydroxyl group. Among these, a carboxyl group and its anhydride are preferable.

  Examples of the polymer (A2) include a copolymer (A21) obtained by copolymerizing an olefin and a radical polymerizable monomer having a reactive group, and a radical polymerizable unsaturated compound having a reactive group. Examples thereof include a graft polymer (A22) obtained by graft polymerization on the coalescence.

The copolymer (A21) is obtained by copolymerizing an olefin and a radical polymerizable monomer having a reactive group, and a structural unit derived from the radical polymerizable monomer having a reactive group is in the main chain. It is an inserted copolymer.
Examples of the olefin used in the copolymer (A21) include α-olefins such as ethylene, propylene, and butene. One olefin may be used alone, or two or more olefins may be used in combination.

  Examples of the reactive radical polymerizable monomer used for the copolymer (A21) include α, β-unsaturated carboxylic acids or anhydrides such as acrylic acid and maleic anhydride. One radically polymerizable monomer having reactivity may be used alone, or two or more kinds may be used in combination.

Specific examples of the copolymer (A21) include, for example, an ethylene-acrylic acid copolymer, an ethylene-acrylic acid ester-maleic anhydride copolymer, and the like. A copolymer (A21) may be used individually by 1 type, and may be used in combination of 2 or more type.
As a method for producing the copolymer (A21), the method described for the polymer (A1) can be used in the same manner.

The graft polymer (A22) can be obtained by graft polymerization of a radical polymerizable unsaturated compound having a reactive group to an olefin polymer. As the olefin polymer, the above-mentioned polymer (A1) can be used.
Examples of the radical polymerizable unsaturated compound having a reactive group include (meth) acrylic acid, fumaric acid, maleic acid or its anhydride, itaconic acid or its anhydride, crotonic acid, and the like. These may be used individually by 1 type and may be used in combination of 2 or more type. “(Meth) acrylic acid” is a general term for acrylic acid and methacrylic acid, and other compounds are also equivalent thereto.

  Specific examples of the graft polymer (A22) include maleic anhydride-modified polypropylene and its chlorinated product, maleic anhydride-modified ethylene-propylene copolymer and its chlorinated product, maleic anhydride-modified propylene-butene copolymer, acrylic acid Examples thereof include modified polypropylene and chlorinated products thereof, acrylic acid-modified ethylene-propylene copolymers and chlorinated products thereof, and acrylic acid-modified propylene-butene copolymers. These may be used individually by 1 type and may be used in combination of 2 or more type.

The radical polymerization initiator used for the graft polymerization can be appropriately selected from ordinary radical polymerization initiators, and examples thereof include organic peroxides and azonitriles.
Examples of the organic peroxide include peroxyketals such as di (t-butylperoxy) cyclohexane; hydroperoxides such as cumene hydroperoxide; dialkyl peroxides such as di (t-butyl) peroxide; And diacyl peroxides such as benzoyl peroxide; and peroxyesters such as t-butylperoxyisopropyl monocarbonate. These may be used individually by 1 type and may be used in combination of 2 or more type.
Examples of the azonitrile include azobisbutyronitrile and azobisisopropylnitrile. These may be used individually by 1 type and may be used in combination of 2 or more type.
As the radical polymerization initiator, benzoyl peroxide and t-butylperoxyisopropyl monocarbonate are preferable.

The use ratio of the radical polymerization initiator and the graft copolymer unit of the graft polymer (A22) is preferably radical polymerization initiator: graft copolymer unit = 1: 100 to 2: 1 (molar ratio), and 1:20 to 1: 1 is more preferred.
The reaction temperature of graft polymerization is usually 50 ° C. or higher, preferably in the range of 80 to 200 ° C. The reaction time for graft polymerization is usually about 2 to 20 hours.

  The manufacturing method of a graft polymer (A22) is not specifically limited, What kind of manufacturing method may be sufficient. Examples of the production method include a method of producing by heating and stirring in a solution, a method of producing by melting and heating and stirring without a solvent, a method of producing by heating and kneading with an extruder. As a solvent in the case of manufacturing in a solution, the solvent illustrated as a manufacturing method of a polymer (A1) can be used similarly.

  The content of the reactive group in the polymer (A22) is preferably 0.01 to 1 mmol, that is, 0.01 to 1 mmol / g, per 1 g of the olefin polymer used for the polymer (A22). The lower limit of the content of the reactive group in the polymer (A22) is more preferably 0.05 mmol / g, further preferably 0.1 mmol / g. 0.5 mmol / g is preferable and, as for the upper limit of content of the reactive group in a polymer (A22), 0.3 mmol / g is more preferable. If the content of the reactive group is 0.01 mmol / g or more, the hydrophilicity increases and the dispersed particle size tends to decrease. Moreover, if content of a reactive group is 1 mmol / g or less, it exists in the tendency for the adhesiveness with respect to a polypropylene base material to increase.

When the reactive group in the graft polymer (A22) is an acidic group such as a carboxyl group or an anhydride thereof, or a sulfonyl group, the acidic group is neutralized with a basic compound. The mechanical stability tends to be good.
Examples of the basic compound include inorganic bases such as sodium hydroxide, potassium hydroxide and ammonia; triethylamine, diethylamine, ethanolamine, dimethylethanolamine, 2-methyl-2-amino-propanol, triethanolamine, morpholine, And organic bases such as pyridine.

  The neutralization rate of the graft polymer (A22) with the basic compound is not particularly limited in the range of 1 to 100 mol% as long as dispersibility in water is obtained, and is preferably 50 mol% or more. As the neutralization rate is higher, the dispersibility of the graft polymer (A22) in water tends to be improved.

<Polymer (B)>
The polymer (B) is a structural unit derived from the radical polymerizable monomer (b1) containing a reactive functional group excluding a carboxyl group and a hydroxyl group (hereinafter referred to as “reactive functional group (i)”). It is a polymer containing. Since the polymer (B) includes a structural unit derived from the radical polymerizable monomer (b1), the polymer (B) forms a crosslinked structure, and thus the coating film strength is increased. Therefore, the adhesiveness of the coating film formed by the aqueous resin dispersion of the present invention to a polyolefin substrate such as a polypropylene substrate is excellent.

  The reactive functional group (i) is a functional group that reacts with the reactive group of the olefin polymer (A). Examples of the reactive functional group (i) include an amino group, an epoxy group, an isocyanato group, and a sulfonyl group, and an epoxy group is preferable from the viewpoint of excellent adhesion to a polyolefin substrate such as a polypropylene substrate.

  Examples of the radical polymerizable monomer (b1) include epoxy group-containing vinyl monomers such as glycidyl (meth) acrylate and methallyl glycidyl ether; and amino groups such as (2-aminoethyl) (meth) acrylate. Examples thereof include vinyl-containing monomers; isocyanato group-containing vinyl monomers such as 2-isocyanatoethyl methacrylate; and sulfonyl group-containing vinyl monomers such as acrylamide t-butylsulfonic acid. Among these, an epoxy group-containing monomer is preferable, and glycidyl (meth) acrylate is particularly preferable. A radically polymerizable monomer (b1) may be used individually by 1 type, and may be used in combination of 2 or more type.

Since the polymer (B) is excellent in polymerizability and improves the stability of the aqueous resin dispersion, in addition to the structural unit derived from the radical polymerizable monomer (b1), the radical polymerizable monomer (b1) is used. It is preferable to have a structural unit derived from another radical polymerizable monomer (b2) other than.
As the radical polymerizable monomer (b2), those having excellent copolymerizability with the radical polymerizable monomer (b1) are preferable, and vinyl monomers having no reactive functional group (i) are more preferable. .

  Examples of the vinyl monomer having no reactive functional group (i) include, for example, a (meth) acrylic acid ester having no carboxyl group, hydroxyl group and reactive functional group (i) (hereinafter referred to as “single amount”). Body (b21) "), aromatic monomer, amide monomer, carboxyl group-containing vinyl monomer, hydroxyl group-containing vinyl monomer, (meth) acrylonitrile, vinyl acetate, propion Examples thereof include vinyl acid vinyl and vinyl versatate. These may be used individually by 1 type and may be used in combination of 2 or more type.

  Examples of the monomer (b21) include methyl (meth) acrylate, ethyl (meth) acrylate, (meth) acrylic acid-n-propyl, (meth) acrylic acid isopropyl, and (meth) acrylic acid-n-. Butyl, (butyl) (meth) acrylate, (t-butyl) (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, octyl (meth) acrylate, (meth) acrylate-2-ethylhexyl, (Meth) acrylic acid nonyl, (meth) acrylic acid lauryl, (meth) acrylic acid stearyl, (meth) acrylic acid ester having an aryl group or aralkyl group having 6 to 12 carbon atoms (for example, benzyl (meth) acrylate) , Dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, (meth) a 2-methoxyethyl toluate, 3-methoxypropyl (meth) acrylate, adducts of polyethylene oxide of (meth) acrylic acid, etc .; (meth) acrylic acid esters having a fluoroalkyl group having 1 to 20 carbon atoms (For example, trifluoromethyl methyl (meth) acrylate, 2-trifluoromethyl ethyl (meth) acrylate, (meth) acrylic acid-2-perfluoroethyl ethyl, etc.) and the like.

Examples of the aromatic monomer include styrene and α-methylstyrene.
Examples of amide monomers include (meth) acrylamide, dimethyl (meth) acrylamide and the like.

Examples of the carboxyl group-containing vinyl monomer include (meth) acrylic acid.
Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate. , (Meth) acrylic acid 2-hydroxybutyl, (meth) acrylic acid polypropylene glycol and the like.

  As the radical polymerizable monomer (b2), the monomer (b21) and the aromatic monomer are preferable from the viewpoint of weather resistance and solvent resistance. Of these, isobutyl methacrylate, tert-butyl methacrylate, butyl acrylate, styrene, and cyclohexyl methacrylate are more preferable, and butyl acrylate and isobutyl methacrylate are particularly preferable from the viewpoint of adhesion to a polypropylene substrate.

  The content of the structural unit derived from the radical polymerizable monomer (b1) in the polymer (B) is preferably 1 to 50% by weight, more preferably 3 to 40% by weight, based on all the structural units. More preferably, it is -30 mass%. If the said content rate is more than a lower limit, the outstanding adhesiveness to polyolefin base materials, such as a polypropylene base material, will be easy to be obtained. If the said content rate is below an upper limit, stability of an aqueous resin dispersion will improve.

  In the aqueous resin dispersion of the present invention, the olefin polymer (A) and the polymer (B) may be dispersed as separate particles, respectively, and the olefin polymer (A) and the polymer (B) The composite particles may be dispersed. From the viewpoint of the stability of the aqueous resin dispersion, it is preferable to include composite particles of the olefin polymer (A) and the polymer (B).

  The mass ratio (B) / (A) (solid content) of the polymer (B) to the olefin polymer (A) contained in the aqueous resin dispersion is preferably 0.5 to 2. The larger the mass ratio (B) / (A) is within the above range, the easier it is to produce the aqueous resin dispersion stably, and the storage stability of the aqueous resin dispersion is improved. Further, the smaller the mass ratio (B) / (A) is within the above range, the better the initial adhesion of the coating film to a polyolefin substrate such as a polypropylene substrate.

  When the olefin polymer (A) has a reactive group, the reactive functional group of the polymer (B) with respect to the total amount of reactive groups of the olefin polymer (A) contained in the aqueous resin dispersion ( The molar ratio of the total amount of i) is preferably 0.3 to 10, and more preferably 0.5 to 8. The larger the molar ratio, the more the bonds with the olefin polymer (A) are sufficiently formed, and the adhesion of the olefin polymer (A) to the polypropylene substrate tends to be less likely to be inhibited. The smaller the molar ratio, the more difficult the particle properties of the olefin polymer (A) and the polymer (B) are, and the better the storage stability tends to be.

  10-60 mass% is preferable and, as for the total solid content concentration of the olefin polymer (A) and polymer (B) in the aqueous resin dispersion of this invention, 20-50 mass% is more preferable.

<Aqueous medium>
The aqueous medium contains water and may contain a solvent other than water.
Examples of solvents other than water include ketones such as methyl ethyl ketone and cyclohexanone; alcohols such as n-propanol, isopropanol, n-butanol, isobutanol, t-butanol and cyclohexanol; ethers such as tetrahydrofuran; 2-methoxyethanol, 2 -Glycol ethers such as ethoxyethanol, 2-butoxyethanol, 2-methoxypropanol, 2-ethoxypropanol, and the like. These may be used individually by 1 type and may be used in combination of 2 or more type.

<Optional component>
The aqueous resin dispersion of the present invention may contain optional components other than the olefin polymer (A), the polymer (B) and the aqueous medium. For example, a surfactant may be added to the aqueous resin dispersion of the present invention for the purpose of improving storage stability.
As the surfactant, various anionic surfactants, cationic surfactants, nonionic surfactants, or polymer surfactants can be used. Furthermore, a so-called reactive surfactant having an ethylenically unsaturated bond in the surfactant component can also be used. Among these, it is preferable to use an anionic surfactant from the viewpoint of improving the storage stability of the aqueous resin dispersion.

  The anionic surfactant is not particularly limited. For example, the reactive surfactant, ADEKA rear soap SR (trade name, manufactured by ADEKA Co., Ltd.) and the non-reactive surfactant Neocor SW-C ( Trade name, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) can be used.

  3 mass parts or less are preferable with respect to 100 mass parts (solid content) of a polymer (B), and, as for content of surfactant (solid content) in the aqueous resin dispersion of this invention, 2 mass parts or less are more. preferable. If content of surfactant is below an upper limit, the storage stability of an aqueous resin dispersion will improve. Moreover, it is hard to impair water resistance, and it is easy to maintain stability when used as a coating composition.

  When the aqueous resin dispersion of the present invention is used as a paint, the aqueous resin dispersion of the present invention includes an inorganic filler, resin beads, a film-forming aid, a substrate wetting agent, a substrate wetting agent, an acrylic resin, and a urethane resin. Various additives such as a polyester resin, a colorant, an antifoaming agent, and a thickener may be included as necessary. Known additives can be used as these additives.

  An organic solvent can be used as a film-forming auxiliary compounded for the purpose of increasing the drying speed or obtaining a surface with a good finish feeling. Examples of the organic solvent include alcohols such as methanol, ethanol and isopropanol; ketones such as acetone; glycols such as ethylene glycol and propylene glycol; glycol ethers such as ethylene glycol monobutyl ether, diethylene glycol monobutyl ether and propylene glycol monomethyl ether.

The method for producing the aqueous resin dispersion of the present invention is not particularly limited. For example, after obtaining the aqueous dispersion of the olefin polymer (A), the raw material single amount of the polymer (B) in the aqueous dispersion Examples thereof include a method (1) of emulsion-polymerizing the polymer, a method (2) of emulsion-polymerizing the raw material monomers of the olefin polymer (A) and the polymer (B) dispersed in an aqueous medium, and the like. In the case of method (1) and method (2), it is not necessary to add a surfactant during the polymerization.
As a method for producing the aqueous resin dispersion, the method (1) is preferable from the viewpoint of polymerizability of the raw material monomer. The aqueous resin dispersion may be produced by separately preparing an aqueous dispersion of the olefin polymer (A) and an aqueous dispersion of the polymer (B) and then mixing the aqueous dispersions. Good.

  A commercially available product may be used as the aqueous dispersion of the olefin polymer (A). Examples of the aqueous dispersion of such an olefin polymer (A) include, for example, Supercron (registered trademark) series (manufactured by Nippon Paper Industries Co., Ltd.), Auroren (registered trademark) series (manufactured by Nippon Paper Industries Co., Ltd.), and Hardren (registered). Trademark) series (manufactured by Toyobo Co., Ltd.) and Aptolock (registered trademark) series (manufactured by Mitsubishi Chemical Corporation).

  The method for producing the aqueous dispersion of the olefin polymer (A) is not particularly limited, and may be a method in which a surfactant is mixed and dispersed. A hydrophilic polymer is grafted to the olefin polymer. It may be a method of dispersing using a graft copolymer. The latter method is preferred because the coating film obtained from the aqueous resin dispersion of the present invention has high water resistance, low bleed-out, etc. and excellent stability.

  The hydrophilic polymer graft-bonded to the olefin polymer is a polymer having an insoluble content of less than 1% by mass when dissolved in water at 25 ° C. at a concentration of 10% by mass. As the hydrophilic polymer, various polymers such as a synthetic polymer, a semi-synthetic polymer and a natural polymer can be used as long as the effects of the present invention are not significantly impaired. The number average molecular weight (Mn) of the hydrophilic polymer is preferably 300 or more because of excellent mechanical stability of the dispersion particles.

  Examples of the synthetic polymer that can be used as the hydrophilic polymer include polyether resins, polyvinyl alcohol resins, and polyvinyl pyrrolidone resins. Examples of natural polymers that can be used as the hydrophilic polymer include starch, gum arabic, tragacanth gum, casein, gelatin, and dextrin. Examples of the semi-synthetic polymer that can be used as the hydrophilic polymer include carboxylated starch, cationized starch, dextrin, ethyl cellulose, carboxylated methyl cellulose, hydroxyethyl cellulose, and cationized cellulose. Among them, preferred is a synthetic polymer that can easily control the degree of hydrophilicity and has stable characteristics. More preferred are polyvinyl alcohol resins, polyvinyl pyrrolidone resins, and polyether resins. In order to control the average particle diameter of the dispersion particles, these may be used singly or in combination of two or more. Among these, a highly hydrophilic polyether resin is particularly preferable. The polyether resin is usually produced by ring-opening polymerization of cyclic alkylene oxide or cyclic alkylene imine.

  Examples of the method of graft-bonding an olefin polymer and a polyether resin include, for example, a method of ring-opening polymerization of a cyclic alkylene oxide in an olefin polymer having a reactive group, a polyether polyol obtained by ring-opening polymerization, etc. And a method in which a reactive group such as polyetheramine is reacted with a reactive group of an olefin polymer.

  The polyether polyol has hydroxyl groups as reactive groups at both ends of a resin having a polyether skeleton. Polyetheramine has a primary amino group as a reactive group at one or both ends of a resin having a polyether skeleton. As the polyether resin to be bonded, polyetheramine is preferable.

  The structural unit of the polyether resin is preferably composed of polyethylene oxide or polyethyleneimine exhibiting hydrophilicity and polypropylene oxide or polypropyleneimine exhibiting hydrophobicity. More preferably, it is composed of polyethylene oxide and polypropylene oxide. The HLB of the polyether resin can be adjusted by the number of repeating units of polyethylene oxide and polypropylene oxide.

  The HLB of the polyether resin can also be adjusted by the amount of the hydrophobic polyether resin used in combination. When a hydrophobic polyether resin is used in combination, the average particle size of the olefin polymer (A) can be controlled. Here, the term “hydrophobic” refers to those having an insoluble content of 1% by mass or more when dissolved in water at 25 ° C. at a concentration of 10% by mass.

  Examples of the polyetheramine include “Jeffamine” M series, D series, ED series, “Surphonamine” L series, etc., manufactured by Huntsman.

  The polyether resin preferably has at least one reactive group capable of reacting with the olefin polymer before bonding with the olefin polymer. Examples of the reactive group include a carboxyl group, a dicarboxylic acid anhydride group, a dicarboxylic acid anhydride monoester group, a hydroxyl group, an amino group, an epoxy group, an isocyanate group, and the like, and preferably has at least an amino group. Since the amino group is highly reactive with various reactive groups such as a carboxylic acid group, a carboxylic anhydride group, a glycidyl group, and an isocyanate group, it is easy to bond the olefin polymer and the polyether resin. The amino group may be primary, secondary, or tertiary, but more preferably is a primary amino group.

  There may be one or more reactive groups in the polyether resin, but a more preferable number of reactive groups is one. When there are two or more reactive groups, there is a possibility that a three-dimensional network structure will be formed when the olefin polymer is combined, and gelation will occur. However, even if it has a plurality of reactive groups, it may not gel, such as in the case of a polyether resin having only one reactive group higher than the others. Examples of such polyether resins include polyether resins having one or more hydroxyl groups and one amino group having a higher reactivity. Here, the reactivity is the reactivity with the reactive group of the olefin polymer.

  The polyether resin in the present invention preferably has a weight average molecular weight (Mw) of 200 to 200,000 as measured by GPC and converted with a polystyrene calibration curve. A more preferable value of the lower limit value of Mw is 300, and a more preferable value is 500. A more preferable value of the upper limit value of Mw is 100,000, a more preferable value is 10,000, and a further preferable value is 3,000. The higher the Mw, the lower the surface energy of the aqueous resin dispersion and the better the wettability. Also, the lower the Mw, the lower the viscosity and the easier it is to prepare a resin dispersion. The GPC measurement is performed by a conventionally known method using a commercially available apparatus using tetrahydrofuran or the like as a solvent.

  In the olefin polymer (A), from the viewpoint of the polymerizability of the radical polymerizable monomer, the olefin polymer and the polyether resin are olefin polymer: polyether resin = 100: 1 to 100: 100 (mass). Those bonded at a ratio of (ratio) are preferred. This mass ratio is more preferably 100: 5 to 100: 70, and still more preferably 100: 10 to 100: 50. The larger the mass ratio of the polyether resin, the smaller the particle size of the olefin polymer (A). Further, the smaller the mass ratio of the polyether resin, the higher the acid value of the aqueous dispersion of the olefin polymer (A), and the adhesiveness to the polypropylene substrate tends to be improved.

  As described above, a method of obtaining an aqueous dispersion of an olefin polymer (A) by dispersing a graft copolymer obtained by grafting a hydrophilic polymer to an olefin polymer in water to obtain an aqueous dispersion of the olefin polymer (A) is not limited to water. Examples include a method of adding a solvent, heating and dissolving as necessary, and then adding water to obtain an aqueous dispersion.

  The aqueous dispersion of the olefin polymer (A) used in the production of the aqueous resin dispersion of the present invention is an aqueous dispersion of an olefin polymer obtained by grafting a hydrophilic polymer to an olefin polymer. A certain Aptolock (registered trademark) series (Mitsubishi Chemical Corporation) is preferred.

In polymerization of the raw material monomer of the polymer (B), either batch polymerization or dropwise polymerization can be used as long as the effects of the present invention are not impaired. Here, batch polymerization is a method in which the whole amount of monomers is charged at once and polymerized. When batch polymerization is employed in the method (1), for example, radical polymerization is performed after mixing the entire amount of the raw material monomer of the polymer (B) with the aqueous dispersion of the olefin polymer (A). Moreover, dripping polymerization is a method of polymerizing while dropping monomers little by little. In the case of employing dropping polymerization in the method (1), for example, radical polymerization is performed while dropping the raw material monomer of the polymer (B) into an aqueous dispersion of the olefin polymer (A).
From the viewpoint of polymerization stability and adhesiveness to a polyolefin substrate such as a propylene substrate, batch polymerization is preferred.

  As the initiator used for radical polymerization, those generally used for radical polymerization can be used. Specific examples include persulfates such as potassium persulfate, sodium persulfate and ammonium persulfate; azobisisobutyronitrile, 2,2′-azobis (2-methylbutyronitrile), 2,2′- Oil solubility of azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2-phenylazo-4-methoxy-2,4-dimethylvaleronitrile, etc. Azo compound; 2,2′-azobis {2-methyl-N- [1,1-bis (hydroxymethyl) -2-hydroxyethyl] propionamide}, 2,2′-azobis {2-methyl-N- [ 2- (1-hydroxyethyl)] propionamide}, 2,2′-azobis {2-methyl-N- [2- (1-hydroxybutyl)] propionamide} 2,2 -Azobis [2- (5-methyl-2-imidazolin-2-yl) propane] and salts thereof; 2,2′-azobis [2- (2-imidazolin-2-yl) propane] and salts thereof; 2′-azobis {2- [1- (2-hydroxyethyl) -2-imidazolin-2-yl] propane} and salts thereof; 2,2′-azobis (2-methylpropyneamidine) and salts thereof; 2 , 2′-azobis [N- (2-carboxyethyl) -2-methylpropionamidine] and other water-soluble azo compounds; benzoyl peroxide, cumene hydroperoxide, t-butyl hydroperoxide, t-butyl peroxy- And organic peroxides such as 2-ethylhexanoate and t-butylperoxyisobutyrate. These initiators may be used individually by 1 type, and may be used in combination of 2 or more type.

In the polymerization, a redox polymerization reaction may be performed by further adding a reducing agent.
As a polymerization method, a method of performing polymerization using a water-soluble initiator, a method of performing polymerization by a redox reaction using an organic peroxide as an initiator and ferrous sulfate or isoascorbic acid as a reducing agent Is preferred.

  When performing the polymerization reaction, a known chain transfer agent such as n-dodecyl mercaptan, t-dodecyl mercaptan, α-methylstyrene dimer may be used as a molecular weight adjusting agent.

  After the polymerization reaction is completed, when cooling and taking out the aqueous resin dispersion, it is preferable to perform a filtration operation in order to prevent contamination of foreign matters and cullet. As the filtration method, a known method can be used. For example, nylon mesh, bag filter, filter paper, metal mesh, etc. can be used.

  The aqueous resin dispersion of the present invention can be used as a primer, a paint, an adhesive, an ink binder, a compatibilizing agent for polyolefin and a different material, and is particularly useful as a paint, an adhesive, and an ink binder. Applications include automobile paints for automobile interiors and exteriors, paints for home appliances such as mobile phones and personal computers, paints for building materials, heat sealants and the like. Among these, it is useful as a primer coating for plastic substrates, particularly polypropylene substrates.

For example, the coating containing the olefin polymer (A) and the polymer (B) can be formed on the substrate surface by baking after applying the aqueous resin dispersion of the present invention to the substrate surface.
The baking temperature is preferably 30 to 200 ° C, more preferably 40 to 180 ° C. When the baking temperature is equal to or higher than the lower limit, it is easy to form a coating film having excellent adhesion to a polyolefin substrate such as a polypropylene substrate. If the baking temperature is not more than the upper limit value, the energy consumption can be reduced.

The state of the olefin polymer (A) and the polymer (B) in the coating film is observed using a transmission electron microscope by staining an ultrathin section prepared by a general gel embedding method with RuO ₄ . Can be determined.

As described above, the aqueous resin dispersion of the present invention includes a structural unit derived from the olefin polymer (A) and the radical polymerizable monomer (b1) containing the reactive functional group (i). The polymer (B) is combined. Thereby, the coating film which has the outstanding adhesiveness also to polyolefin base materials, such as a polypropylene base material, can be formed.
In addition, since the coating film formed from the aqueous resin dispersion of the present invention has excellent adhesion to substrates other than polyolefin substrates such as metal substrates, other than polyolefin substrates and metal substrates, etc. It can be suitably used as an adhesive or the like for adhering to the substrate.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited by the following description. In the examples, “parts” and “%” represent “parts by mass” and “% by mass”, respectively.

[Evaluation of adhesion]
1. Initial adhesiveness 60 parts by weight of diethylene glycol monobutyl ether as a film forming aid and TEGO (registered trademark) WET KL-245 (trade name, EVONIK) as a base material wetting agent with respect to 100 parts by mass of the solid content of the aqueous resin dispersion of each example 3 parts) and BYK-345 (manufactured by Nippon Big Chemie Co., Ltd.) were added in portions and stirred at 700 rpm for 5 minutes using a homodisper stirrer (Polytron PT-3100). After leaving at room temperature for one day, an aqueous paint was obtained by performing filtration using 300 mesh.

  Next, the surface of the substrate having a thickness of 3 mm formed from polypropylene (“TSOP-6” manufactured by Nippon Polypro Co., Ltd.) was wiped with isopropyl alcohol. The obtained water-based paint was spray-coated on this substrate so that the dry film thickness was 20 μm, set at room temperature for 10 minutes, and then baked at 70 ° C. or 90 ° C. for 30 minutes with a safe ben dryer to form a coating film. . This was left still at room temperature for 1 day to obtain a test piece.

Next, 11 cuts were made at intervals of 1 mm in length and breadth so as to reach the substrate on the coating surface of the test piece to make 100 grids. Next, after attaching a cellophane adhesive tape on the grid, the adhesive tape was peeled off rapidly. The state of the coating film after peeling the adhesive tape was observed, and the number of strips (peeling cells) of the coating film that was peeled was confirmed. The initial adhesion of the coating film to the substrate was evaluated based on the following evaluation criteria.
○: The peeling mass is 0 square in 100 squares.
(Triangle | delta): The peeling mass is 1-60 masses in 100 masses.
X: In 100 squares, a peeling mass is 61 squares or more.

2. Water Resistance Adhesive After obtaining a test piece in the same manner as the “initial adhesion” evaluation method, the test piece was immersed in warm water at 60 ° C. for 1 day. Subsequently, the test piece was taken out from the warm water and dried at 23 ° C. for 10 minutes.
Next, 11 cuts were made at intervals of 1 mm in length and breadth so as to reach the substrate on the coating surface of the test piece to make 100 grids. Next, after attaching a cellophane adhesive tape on the grid, the adhesive tape was peeled off rapidly. The state of the coating film after peeling the adhesive tape was observed, and the number of strips (peeling cells) of the coating film that was peeled was confirmed. The water-resistant adhesion of the coating film to the substrate was evaluated based on the same evaluation criteria as the initial adhesion.

[Example 1]
In a flask equipped with a stirrer, a reflux condenser, and a temperature controller, Aptolock (registered trademark) BW-5683 (Mitsubishi Chemical Corporation: solid content 30%) which is an aqueous dispersion of the olefin polymer (A) Of 333.3 parts (100 parts in solid content) and 126.3 parts of deionized water were added, and the temperature was raised to 30 ° C.
Aptolock (registered trademark) BW-5683 is an aqueous dispersion of an olefin polymer prepared by reacting a maleic anhydride-modified propylene-butene copolymer with a hydrophilic polymer. The olefin polymer has a melting point (Tm) of 70 ° C., a weight average molecular weight (Mw) of about 150,000, maleic anhydride of 0.3 mmol / g per 1 g of propylene-butene copolymer, and per 100 g of propylene-butene copolymer. The hydrophilic polymer was 10 g.
Next, 5.2 parts of glycidyl methacrylate (GMA) as the radical polymerizable monomer (b1) and 47.4 parts of butyl acrylate (BA) and isobutyl methacrylate (b2) as the radical polymerizable monomer (b2) iBMA) 47.4 parts was added, heated to 60 ° C. and held for 1 hour. Further, 0.02 part of perbutyl (registered trademark) H69 (trade name, manufactured by NOF CORPORATION, solid content 69%) as an initiator, 0.0002 part of ferrous sulfate as a reducing agent, .000027 parts, 0.08 part of sodium isoascorbate monohydrate, and 2 parts of deionized water were added to initiate the polymerization.
After detecting the exothermic peak of polymerization, 0.03 part of perbutyl (registered trademark) H69 and 10 parts of deionized water were added dropwise over 15 minutes. After completion of dropping, the mixture was aged at 60 ° C. for 30 minutes to obtain an aqueous resin dispersion.

[Examples 2 and 3]
An aqueous resin dispersion was obtained in the same manner as in Example 1 except that the amounts of the radical polymerizable monomer (b1) and the radical polymerizable monomer (b2) used were changed as shown in Table 1.

[Comparative Example 1]
An aqueous resin dispersion was prepared in the same manner as in Example 1 except that the radical polymerizable monomer (b1) was not used and the amount of the radical polymerizable monomer (b2) used was changed as shown in Table 1. Obtained.

[Comparative Example 2]
Example 2 except that GMA corresponding to the radical polymerizable monomer (b1) was changed to 4-hydroxybutyl acrylate (4HBA) not corresponding to the radical polymerizable monomer (b1) as shown in Table 1. Similarly, an aqueous resin dispersion was obtained.

  Table 1 shows the evaluation results of the initial adhesion and water-resistant adhesion of the coating film formed using the aqueous resin dispersion of each example. In addition, “100/100” in Table 1 means that all 100 squares remained without peeling out of 100 squares formed on the coating film. “0/100” means that 100 out of 100 squares formed on the coating film are peeled off, and the remaining squares are 0 squares.

  As shown in Table 1, the combination of the olefin polymer (A) and the polymer (B) containing the structural unit derived from the radical polymerizable monomer (b1) containing the reactive functional group (i). In Examples 1-3, it replaces with a polymer (B), the comparative example 1 using the polymer containing the structural unit derived from the radically polymerizable monomer (b2) which does not have a reactive functional group, and a polymer ( Compared to Comparative Example 2 using a polymer containing a structural unit derived from 4HBA having a hydroxyl group that is a reactive functional group other than the reactive functional group (i) in place of B), the adhesive property is excellent even by baking at 75 ° C. A coating film having Moreover, the coating film formed using the aqueous resin dispersions of Examples 1 to 3 was excellent in water-resistant adhesion as compared with the coating film formed using the aqueous resin dispersion of Comparative Example 1.

Claims (3)

  An olefin polymer (A) and a polymer (B) containing a structural unit derived from a radical polymerizable monomer (b1) containing a reactive functional group excluding a carboxyl group and a hydroxyl group are dispersed in an aqueous medium. An aqueous resin dispersion.   The aqueous resin dispersion according to claim 1, wherein the radical polymerizable monomer (b1) is a radical polymerizable monomer having an epoxy group.   The aqueous resin dispersion according to claim 1 or 2, wherein the olefin polymer (A) does not contain a chlorine atom.