JP6225518B2 - Reactive polymer emulsifier for epoxy resin and aqueous resin composition containing the same - Google Patents

Description

The present invention relates to a reactive polymer emulsifier for epoxy resin and an aqueous resin composition containing the same.

  In recent years, in the paint field, there is an increasing demand for water-based paints due to environmental and safety issues. In order to meet this requirement, an aqueous emulsion is prepared using a large amount of a surfactant as an emulsifier for the purpose of maintaining a stable dispersion state of the resin in water. However, the water resistance of the coating film is lowered due to the influence of the surfactant remaining in the coating film after the coating film is formed, and there is a problem that it has adverse effects such as blistering and whitening due to water absorption, and a decrease in hardness.

In order to solve this problem, Patent Document 1 discloses a monomer having a carboxyl group in a polymer obtained by polymerizing a monomer having an epoxy group and a monomer having a polyalkylene glycol ether structure. It is disclosed that a reactive polymer having a vinyl group can be obtained by reacting with water, and a cured film having excellent hardness can be obtained by crosslinking an aqueous resin composition obtained by self-emulsifying the reactive polymer by UV irradiation. It is disclosed that can be formed.
However, in this method, the emulsion stability of the aqueous resin composition is not sufficient. In addition, since an aqueous resin composition using an epoxy resin is often used not only indoors but also outdoors, this aqueous resin composition that is crosslinked by UV irradiation is difficult to be stored in a harsh environment. It is not suitable as a paint for outdoor or building materials.

Patent Document 2 discloses that an aqueous resin composition containing a poly (N-acylethyleneimine) polymer as a polymer emulsifier for an epoxy resin has excellent emulsification stability and has a film such as water resistance and strength of a coating film. It is disclosed that it is excellent in physical properties.
However, since the epoxy resin and the polymer emulsifier have not reacted and the emulsifier remains in the coating film, the coating film made of this aqueous resin composition still has insufficient water resistance.

JP 2009-149875 A JP 10-46008 A

The present invention has been made based on the circumstances as described above, and its purpose is to have excellent emulsion stability and to form a coating film having excellent water resistance. It is to provide an aqueous resin composition suitable for a paint for building materials, and to provide a reactive polymer emulsifier for epoxy resin suitable for the aqueous resin composition.

The inventors have obtained a copolymer obtained by copolymerizing a monomer mixture containing glycidyl (meth) acrylate and a specific monomer in a specific ratio and having a weight average molecular weight within a predetermined range. It has been found that the above object can be achieved by incorporating an aqueous resin composition as a reactive polymer emulsifier for an epoxy resin .

That is, the reactive polymer emulsifier of the present invention is obtained by copolymerizing a monomer mixture containing glycidyl (meth) acrylate (A) and a monomer (B) represented by the following general formula (1). The glycidyl (meth) acrylate (A) content in the monomer mixture is 20 to 60 mol%, the monomer (B) content is 40 to 80 mol%, and glycidyl (meth) acrylate (A) and It is a reactive polymer emulsifier for epoxy resins comprising a copolymer having a total content of the monomer (B) of 85 mol% or more and a weight average molecular weight of 3,000 to 30,000.

（式中、ｎ＝２〜９０、ＸおよびＹは、それぞれ独立してＨまたはＣＨ_３を示す。）

(In the formula, n = 2 to 90, X and Y each independently represent H or CH _3. )

Moreover, the aqueous resin composition of this invention is an aqueous resin composition containing the epoxy resin and the reactive polymer emulsifier for epoxy resins of this invention.

By containing the reactive polymer emulsifier for epoxy resin of the present invention in the aqueous resin composition, the aqueous resin composition of the present invention excellent in emulsion stability and water resistance of the coating film can be obtained. The aqueous resin composition of the present invention is an aqueous epoxy resin composition containing an epoxy resin and water, and a cured film can be formed by further containing a curing agent. Therefore, the aqueous resin composition of the present invention can be stored in harsh environments and is suitable as a paint for outdoor use or building materials.
Hereinafter, the reactive polymer emulsifier for epoxy resin of the present invention is also simply referred to as a reactive polymer emulsifier.

  Hereinafter, the reactive polymer emulsifier of the present invention and the aqueous resin composition containing the same will be described. In this specification, (meth) acrylate represents acrylate or methacrylate, (meth) acryl represents acryl or methacryl, and (meth) acrylo represents acrylo or methacrylo. In addition, the numerical range defined using the symbol “to” in this specification includes numerical values at both ends (upper limit and lower limit) of “to”. For example, “2 to 5” represents 2 or more and 5 or less.

(Reactive polymer emulsifier)
The reactive polymer emulsifier of the present invention is a copolymer obtained by copolymerizing a monomer mixture containing glycidyl (meth) acrylate (A) and the monomer (B) represented by the general formula (1). Composed of coalescence.

  Glycidyl (meth) acrylate (A) is glycidyl acrylate or glycidyl methacrylate. Glycidyl methacrylate is preferably used because it is easily available industrially. Glycidyl acrylate and glycidyl methacrylate may be used in combination.

The monomer (B) is represented by the general formula (1). In the formula, X is H or CH ₃ , Y is H or CH ₃ , and X and Y may be the same or different.
n is 2-90, Preferably it is 3-70, More preferably, it is 4-60. When n is less than 2, the hydrophilicity of the resulting copolymer is lowered, and the emulsification property may be lowered. Moreover, when n exceeds 90, there exists a possibility that the water resistance of the coating film formed from an aqueous resin composition may fall. A monomer (B) may be used individually by 1 type, and may use 2 or more types together.

The content of the glycidyl (meth) acrylate (A) in the monomer mixture is from 20 to 60 mol%, preferably from 20 to 50 mol%, more preferably 20 to 40 mol%.
The content of the monomer in the monomer mixture (B) is 40 to 80 mol%, preferably 50 to 80 mol%, more preferably from 60 to 80 mol%.
Therefore, the content ratio of the glycidyl in the monomer mixture (meth) acrylate (A) monomer and (B) is 20 / 80-60 / 40, preferably 20 / 80-50 / 50, more preferably Is 20/80 to 40/60.
If the content of glycidyl (meth) acrylate (A) and monomer (B) in the monomer mixture is out of the above range, the emulsifiability of the resulting copolymer may be reduced.

  The monomer mixture in the present invention may contain other monomers together with glycidyl (meth) acrylate (A) and monomer (B). Other monomers are monomers other than the monomers (A) and (B) described above, for example, styrene, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate. , (Meth) acrylic acid, (meth) acrylamide, N, N′-diethylacrylamide, N, N′-dimethylacrylamide, N-isopropyl (meth) acrylamide, (meth) acrylonitrile, methoxypolypropylene glycol (degree of polymerization 2-30) ) Mono (meth) acrylate and the like. Other monomers may be used alone or in combination of two or more.

  The content of other monomers in the monomer mixture is 15 mol% or less (0 to 15 mol%), preferably 10 mol% or less (0 to 10 mol%), and more preferably 5 mol%. The following is (0 to 5 mol%). That is, the total content of acrylate (A) and monomer (B) is 85 mol% or more (85 to 100 mol%) in the monomer mixture, preferably 90 mol% or more (90 to 100 mol%). More preferably, it is 95 mol% or more (95 to 100 mol%).

The copolymer obtained by copolymerizing a monomer mixture containing at least glycidyl (meth) acrylate (A) and monomer (B) has a weight average molecular weight of 3,000 to 30,000, preferably Is from 5,000 to 25,000, more preferably from 7,000 to 15,000. If the weight average molecular weight is less than 3,000, the water resistance of the coating film formed from the aqueous resin composition may be lowered, and if it exceeds 30,000, the emulsifiability may be lowered.
In addition, the weight average molecular weight of a copolymer can be measured using a gel permeation chromatography (GPC), for example.

Next, a method for producing a copolymer by copolymerizing a monomer mixture will be described.
The copolymer in the present invention can be obtained by radical polymerization of a monomer mixture containing at least glycidyl (meth) acrylate (A) and monomer (B). The polymerization can be performed by a known method. For example, solution polymerization, suspension polymerization, and emulsion polymerization may be mentioned, but solution polymerization is preferable in terms of easy adjustment of the weight average molecular weight to the above range.

A well-known thing can be used for a polymerization initiator. For example, di (4-t-butylcyclohexyl) peroxydicarbonate, organic peroxides such as 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, 2,2′-azobis Examples thereof include azo polymerization initiators such as isobutyronitrile. These polymerization initiators may be used alone or in combination of two or more.
The usage-amount of a polymerization initiator can be suitably set according to the combination of the monomer to be used, reaction conditions, etc.
In addition, when charging the polymerization initiator, for example, the whole amount may be charged all at once, a part may be charged all at once and the remaining may be dropped, or the whole amount may be dropped. Moreover, it is preferable to add a polymerization initiator together with the monomer because the reaction can be easily controlled, and it is preferable to add a polymerization initiator even after the monomer is added because the residual monomer can be reduced.

As a polymerization solvent used in the solution polymerization, a solvent in which a monomer and a polymerization initiator are dissolved can be used. Specifically, methanol, ethanol, 1-propanol, acetone, methyl ethyl ketone, propylene glycol monomethyl An ether etc. can be mentioned.
As for the density | concentration of the monomer mixture with respect to a polymerization solvent, 10-60 mass% is preferable, More preferably, it is 20-50 mass%. If it is less than 10% by mass, the monomer tends to remain, the molecular weight of the resulting copolymer may be reduced, and if it exceeds 60% by mass, it may be difficult to control heat generation.
When the monomer is added, for example, the whole amount may be charged all at once, a part may be charged all at once and the rest may be dropped, or the whole amount may be dropped. From the viewpoint of easy control of heat generation, it is preferable to prepare a part of the solution and add the rest, or add the entire amount.
The polymerization temperature depends on the polymerization solvent and is, for example, 50 ° C to 110 ° C.
The polymerization time depends on the type of polymerization initiator and the polymerization temperature. For example, when di (4-t-butylcyclohexyl) peroxydicarbonate is used as the polymerization initiator, the polymerization temperature is set to 70 ° C. A suitable time is 6 hours.

  By performing the above polymerization reaction, a copolymer according to the reactive polymer emulsifier of the present invention is obtained. The obtained reactive polymer emulsifier may be used as it is for the preparation of the aqueous resin composition, or may be isolated from the reaction solution after the polymerization reaction by filtration or purification.

[Aqueous resin composition]
The aqueous resin composition of the present invention is an aqueous resin composition containing an epoxy resin and the reactive polymer emulsifier of the present invention, and further containing water. In some cases, the aqueous resin composition further includes pigments, curing agents, additives, and the like. A component may be included.

  As the epoxy resin, a known epoxy resin can be used. Specifically, bisphenol A type, bisphenol F type, brominated bisphenol A type, hydrogenated bisphenol A type, bisphenol S type, bisphenol AF type, biphenyl type and other epoxy compounds having a bisphenyl group, polyalkylene glycol type, Bifunctional glycidyl ether epoxy resin such as alkylene glycol type epoxy compound, epoxy compound having naphthalene ring, epoxy compound having fluorene group; phenol novolac type, orthocresol novolac type, trishydroxyphenylmethane type, tetraphenylol Polyfunctional glycidyl ether type epoxy resin such as ethane type; glycidyl ester type epoxy resin of synthetic fatty acid such as dimer acid, etc., and one kind selected from these epoxy resins alone , Or it can be used as a mixture of two or more.

The aqueous resin composition in the present invention can be obtained by emulsifying an epoxy resin using a reactive polymer emulsifier and water.
The content of the reactive polymer emulsifier with respect to the epoxy resin is preferably 1 to 30% by mass, more preferably 3 to 20% by mass, and further preferably 5 to 5% by mass in terms of emulsion stability and water resistance of the coating film. 10% by weight. Further, the solid content concentration in the aqueous resin composition is preferably 30 to 90% by mass, more preferably 40 to 85% by mass, and further preferably 50 to 80% by mass in terms of emulsion stability.

  Examples of the pigment include titanium oxide, yellow iron oxide, red iron oxide, carbon black, phthalocyanine blue, phthalocyanine green, azo red, quinacridone red, benzimidazolone yellow, and other colored pigments, calcium carbonate, barium sulfate, kaolin, clay, Examples include extender pigments such as talc.

  As a hardening | curing agent, a well-known hardening | curing agent for epoxy resins can be used according to the kind of epoxy resin. Specifically, amines such as ethylenediamine, propylenediamine, phenylenediamine, pentaethylenehexamine, tetraethylenepentamine, triethylenetetramine, diethylenetriamine, metaxylenediamine, isophoronediamine, norbornenediamine, polycarboxylic acids, polycarboxylic anhydride And imidazoles such as phenyl imidazole, polymercaptans, polyamide resins, dicyandiamides, dihydrazides such as adipic acid dihydrazide, and the like.

Examples of the additive include a dispersant, an antifoaming agent, a rust preventive agent, a film forming aid, a viscosity adjusting agent, a curing catalyst, a surface adjusting agent, a plasticizer, an ultraviolet absorber, and an antioxidant.
As an emulsification method, a known method can be used. Examples thereof include a high pressure emulsification method, a phase inversion emulsification method, and a D phase emulsification method.

  The aqueous resin composition of the present invention can be used, for example, in a wide range of applications related to building materials. Specifically, paints for materials such as concrete, cement mortar, various metals, leather, glass, etc. It can be used for adhesives, sealing materials, cement admixtures, flooring materials, anticorrosive paints, interior paints, exterior paints, and the like. Since the aqueous resin composition of the present invention is excellent in the water resistance of the coating film, it is particularly preferable to use it as an outdoor paint or adhesive.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.
The monomer abbreviations and emulsifiers used in Examples and Comparative Examples are shown below.
GMA: Glycidyl methacrylate MEM 4: Monomer of X = CH ₃ , Y = CH ₃ , n = 4 in general formula (1) AN: Acrylonitrile Emulsifier A: Polyethylene glycol-polypropylene glycol-polyethylene glycol block copolymer Emulsifier B: Polyoxy Ethylene nonyl phenyl ether (degree of polymerization of ethylene glycol: 10)

Example 1
300 g of 1-propanol was charged into a 1 L separable flask equipped with a stirrer, a thermometer, a cooler, a dropping funnel, and a nitrogen introduction tube, and the atmosphere was placed in a nitrogen atmosphere. A monomer solution in which 46 g of GMA (product name: Blemmer GMA (manufactured by NOF Corporation)) and 354 g of MEM4 (product name: Blemmer PME-200 (manufactured by NOF Corporation)) are mixed, and 100 g of 1-propanol And 26 g of di (4-t-butylcyclohexyl) peroxydicarbonate (product name: Perroyl TCP (manufactured by NOF Corporation)) were prepared.
The temperature in the reaction vessel was raised to 70 ° C., and the monomer solution and the polymerization initiator solution were simultaneously added dropwise over 3 hours. Then, it was made to react at 70 degreeC for 3 hours, and the copolymer as a reactive polymer emulsifier was obtained.
36.4 parts of the obtained reactive polymer emulsifier and 363.6 parts of bisphenol A type epoxy resin (product name: JER828 (manufactured by Mitsubishi Chemical Corporation)) are mixed, and the mixture is transferred using 100 parts of ion-exchanged water. Phase emulsification was performed to obtain an aqueous resin composition.
The weight average molecular weight of the obtained reactive polymer emulsifier, the emulsion stability of the aqueous resin composition, and water resistance were evaluated under the following conditions.

(Measurement of weight average molecular weight)
The weight average molecular weight of the reactive polymer emulsifier was determined under the following conditions using gel permeation chromatography (GPC).
Apparatus: manufactured by Tosoh Corporation, HLC-8220
Column: manufactured by shodex, LF-804
Standard substance: Polyethylene glycol Eluent: THF (tetrahydrofuran)
Flow rate: 1.0 ml / min
Column temperature: 40 ° C
Detector: RI (differential refractive index detector)

[Evaluation of emulsion stability]
30 g of the aqueous resin composition was placed in a 50 mL screw tube and stored in a constant temperature bath at 40 ° C. It was confirmed visually and evaluated according to the following criteria.
◎: Maintain a uniform emulsified state for 1 month or longer ○: Maintain a uniform emulsified state for 1 week or longer and less than 1 month Δ: Maintain a uniform emulsified state for 3 days or longer and shorter than 1 week ×: Separation or precipitation by 3 days

[Evaluation of water resistance]
50 parts by mass of an aqueous resin composition and 3.6 parts by mass of diethylenetriamine as a curing agent were blended and applied to a 10 cm × 10 cm steel plate with a bar coater so that the dry film thickness was 60 μm. A test piece was prepared by drying for 3 hours.
The obtained test piece was immersed in ion-exchanged water at room temperature for 1 hour, the mass increase rate before and after immersion was measured, and evaluated according to the following criteria.
◎: 0 to less than 0.5% by mass ○: 0.5% by mass or more, less than 1% by mass Δ: 1% by mass or more, less than 1.5% by mass ×: 1.5% by mass or more

Moreover, the coating film after being immersed in ion-exchange water was visually observed, and the external appearance was evaluated according to the following criteria.
○: There is no change in the coating film.
(Triangle | delta): A whitening area is less than 5% with respect to the total area of a coating film.
X: The whitening area is 5% or more with respect to the total area of the coating film.

(Examples 2 and 3)
Except that the amount of the polymerization initiator in Example 1 was changed, the same operation as in Example 1 was performed to obtain a copolymer as a reactive polymer emulsifier.
The weight average molecular weight of the obtained reactive polymer emulsifier, the emulsion stability of the aqueous resin composition, and the water resistance were evaluated in the same manner as in Example 1.

Example 4
A copolymer as a reactive polymer emulsifier was obtained in the same manner as in Example 1 except that the monomer ratio and the amount of the polymerization initiator in Example 1 were changed.
The weight average molecular weight of the obtained reactive polymer emulsifier, the emulsion stability of the aqueous resin composition, and the water resistance were evaluated in the same manner as in Example 1.

(Example 5)
A copolymer as a reactive polymer emulsifier was obtained in the same manner as in Example 1 except that the type and ratio of the monomer and the amount of the polymerization initiator in Example 1 were changed.
The weight average molecular weight of the obtained reactive polymer emulsifier, the emulsion stability of the aqueous resin composition, and the water resistance were evaluated in the same manner as in Example 1.

(Examples 6 and 7)
Except having changed the addition amount of the reactive polymer emulsifier in Example 2 , operation similar to Example 2 was performed and the aqueous resin composition was obtained.
The emulsion stability and water resistance of the obtained aqueous resin composition were evaluated in the same manner as in Example 1.

(Comparative Examples 1 and 2)
Except having changed the reactive polymer emulsifier in Example 1, operation similar to Example 1 was performed and the aqueous resin composition was obtained.
The weight average molecular weight of the emulsifier used, the emulsion stability of the aqueous resin composition, and the water resistance were evaluated in the same manner as in Example 1.

(Comparative Examples 3-5)
A copolymer as a reactive polymer emulsifier was obtained in the same manner as in Example 1 except that the monomer ratio and the amount of the polymerization initiator in Example 1 were changed.
The weight average molecular weight of the obtained reactive polymer emulsifier, the emulsion stability of the aqueous resin composition, and the water resistance were evaluated in the same manner as in Example 1.
The results of Examples 1 to 7 are summarized in Table 1, the results of Comparative Examples 1 and 2 are summarized in Table 2, and the results of Comparative Examples 3 to 5 are summarized in Table 3, respectively.

  In Examples 1 to 7 related to the aqueous resin composition using the reactive polymer emulsifier of the present invention, all were excellent in emulsion stability and water resistance of the coating film.

On the other hand, in Comparative Examples 1 and 2 using a conventional emulsifier, blistering or whitening due to water absorption was observed after the coating film of the aqueous resin composition was immersed.
Moreover, the comparison using each reactive polymer emulsifier prepared so that each content of the glycidyl (meth) acrylate (A) and the monomer (B) represented by the general formula (1) exceeds the specified range of the present invention In Examples 3 and 4, both the emulsion stability and the water resistance of the coating film were inferior. In Comparative Example 4, since the coating film made of the aqueous resin composition could not be formed, the water resistance of the coating film could not be evaluated.
Furthermore, in Comparative Example 5 using a reactive polymer emulsifier having a weight average molecular weight exceeding the specified range of the present invention, the water resistance of the coating film was good, but the emulsion stability was not sufficient.

Claims (2)

A glycidyl (meth) acrylate (A) and a monomer mixture containing the monomer (B) represented by the following general formula (1) are copolymerized to obtain a glycidyl (meth) acrylate ( The content of A) is 20 to 60 mol%, the content of monomer (B) is 40 to 80 mol%, and the total content of glycidyl (meth) acrylate (A) and monomer (B) is 85 mol %, A reactive polymer emulsifier for epoxy resin comprising a copolymer having a weight average molecular weight of 3,000 to 30,000.

(In the formula, n = 2 to 90, X and Y each independently represent H or CH _3. ) An aqueous resin composition comprising an epoxy resin and the reactive polymer emulsifier for epoxy resin according to claim 1.