JPH02251502A - Preparation of crosslinking agent-containing emulsified polymer emulsion - Google Patents

Abstract

PURPOSE:To provide the subject emulsion by emulsion-polymerizing an ethylenic unsaturated monomer in the pressure of an allyl group-containing surfactant and a water-insoluble cross-linking agent to encapsulate the water-insoluble cross-linking agent in the emulsified polymer particles. CONSTITUTION:(C) An ethylenic unsaturated monomers [e.g. styrene or alkyl (meth)acrylate] is emulsion-polymerized in the pressure of (A) an allyl group- containing surfactant [e.g. one having allyl group, hydrophilic group and hydrophobic group in the molecule such as a compound of formula I (X is Na, K, NH4, etc.; R is 8 to 18C alkyl)] and (B) a water-insoluble cross-linking agent (preferably polyepoxide such as a polyhydric alcohol polyglycidyl ether of formula II) to provide the objective emulsion. The component A is preferably 0.5-3.0wt.% based on the total amount of the components B+C.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a polymer emulsion in which a water-insoluble crosslinking agent is encapsulated in emulsion polymer particles.

Emulsions in which crosslinking agents are encapsulated in emulsion polymer particles are already known. However, from the viewpoint of crosslinking and curability, if a large amount of crosslinking agent is contained in the particles, problems such as generation of aggregates during emulsion polymerization and a decrease in the stability of the emulsion polymer arise.

In order to improve this, the only way to improve this is to increase the amount of surfactant used compared to when no crosslinking agent is used, but this causes problems such as a decrease in the water resistance, corrosion resistance, and glabellar adhesion of the heat-cured coating film. be. For this reason, at present, crosslinking agent-containing emulsion polymer emulsions have not yet been fully put to practical use as heat-curable coatings that require high performance.

The present invention solves the above problems, and contains a cross-linking agent that does not generate aggregates even when a large amount of cross-linking agent is included, is stable at room temperature, and can form a high-performance cured coating film by heating after painting. The present invention relates to a method for producing emulsion polymer 21ulsion. That is, the present invention provides (C) an ethylenic compound in the presence of (A) an allyl group-containing surfactant [hereinafter referred to as component (A)] and (B) a water-insoluble crosslinking agent E hereinafter referred to as component (B). The present invention provides a method for producing a crosslinking agent-containing emulsion polymer emulsion, which comprises emulsion polymerizing an unsaturated heptamer E (hereinafter referred to as component (C)).

One feature of the present invention is that an allyl group-containing surfactant [(A) component J] is used as a surfactant for emulsion polymerization. The allyl group (CH!-CH-CH,
-) rarely polymerizes alone in emulsion polymerization reactions, and other polymerizable unsaturated polymers [for example, (
It has the property of copolymerizing with component C). Therefore, when component (C) is emulsion polymerized in the presence of components (A) and (B) above, component (B) is water-insoluble, so it is dispersed in the form of fine particles in water, and around it, (C) The emulsion polymerization of the components is carried out to form a fine particulate emulsion polymer of the component (C) which includes the component (B).On the other hand, regarding the component (A), the aryl group is formed in the emulsion polymerization of the component (C). Sometimes applicable (
It is thought that it is copolymerized with a part of component C) and chemically bonded to the surface layer of the emulsion polymer fine particles, and the hydrophilic group portion of component (A) is suspended in the water. As a result, the component (A) is
It hardly forms polymer particles by itself, and at least most of it copolymerizes with a part of component (C).
Because it is chemically bonded to the emulsion polymer fine particles consisting of component B) and component (C), it effectively performs the surfactant's function of stably dispersing the fine particles in water. Even if a large amount of component (B) is used, the resulting emulsion is stable and almost no aggregates are formed. Furthermore, it seems that there are almost no individual fine particles of the crosslinking agent or fine particles composed of components (A) and (B) in the emulsion of the present invention. Of course, an allyl group-unbonded surfactant may be used in combination as long as the characteristics of the present invention described above are not lost.

The method of the present invention will be explained in more detail below.

(A) Component naryl group-containing surfactant Any type of surfactant, anionic, cationic, amphoteric, or nonionic, as long as it has one allyl group, a parent group, and a hydrophobic group in one molecule. Surfactants can also be used.

Specifically, for example, compounds represented by the following general formulas (1) to (2) are preferably used.

■ Anionic: ■ Nonionicity: Such.

(In the formula, X = Na % K 1N Ha, etc.) ■
Cationicity: CH.

CH, -CH-CH, -N'''-R.Y-Cl.

CH.

Such.

(In the formula, ¥-CQ, CH, Coo, etc.) etc.

(In the formula, n is an integer of 1 or more) In the general formulas ■ to ■ above, R is all C, ~C1
It represents an alkyl group of m or an alkenyl group of C, to C1.

Component (B): Water-insoluble crosslinking agent A component that can constitute the core of the particulate emulsion polymer in the emulsion obtained by the method of the present invention, and the surface of the emulsion is the component (C) described below. After coating, each component is melted by heating, and a cured coating film is formed mainly based on the crosslinking reaction between component (B) and component (C).

The component (B) is dissolved in water or (C) at room temperature to polymerization temperature.
It is preferable that it does not react with component (C) and has little or no solubility in water, but is freely compatible with component (C) in any proportion. In addition, component (B) and (C
It is desirable that the mixture with component ) be in a liquid state and have a viscosity within a range that allows the mixture to be dispersed in the form of fine particles in water.

Since component (B) needs to be melted and crosslinked with the emulsion polymer of component (C) by heating, the components must mutually have functional groups that can react complementary to each other to form a crosslinking bond. Preferably. For example, when using an ethylenically unsaturated monomer having a carboxyl group as the component (C), it is desirable to use a polyepoxide compound as the component (B), and an ethylenically unsaturated monomer having a hydroxyl group as the component (C). When using, it is convenient to use a polyN-alkoxymethyl compound or a blocked polyisocyanate compound as component (B).

Of course, component (B) is not limited to these,
In addition, alkoxysilane group-containing compounds can also be used.

Examples of the above-mentioned polyepoxide compounds include the following.

■ Polyglycidyl ether of polyhydric alcohol: etc.

■Polyglycidyl ether of polyhydric phenol; etc.

■ Polyglycidyl ether of polyhydric carboxylic acid: etc.

■ Poly(epoxidized cyclohexenyl) compounds: etc.

■ Poly(epoxidized vinylcyclohexenyl) compounds: etc.

(m% n=1 to 5) The poly N-alkoxymethyl compound is preferably a low molecular weight compound obtained by etherifying methylolated melamine or benzoguanamine with alcohol, for example.

As the blocked polyisocyanate, for example, aliphatic, alicyclic, or araliphatic diisocyanates such as oxime-blocked hexamethylene diisocyanate, xylylene diisocyanate, and impolon diisocyanate are suitable.

Component (C): an ethylenically unsaturated monomer having at least one polymerizable unsaturated bond in one molecule which is emulsion polymerized in the presence of the above components (A) and (B) in the present invention. The polymer formed by this emulsion polymerization is mainly composed of fine particles ((
B) Coating the surface of the component. In other words, the emulsion obtained by the method of the present invention has fine particles having a multilayer structure in which component (B) is the core and the surface layer is covered with a polymer layer based on component (C) dispersed in an aqueous medium. This is what happens.

The component (C) does not react with the aqueous medium or the component (B) at room temperature to the polymerization temperature, is freely compatible with the component (B) in any proportion, and is furthermore at a temperature higher than the polymerization temperature. It is preferable that the composition contains a functional polymer having a functional group capable of crosslinking with component (B). Specifically, examples include styrene, vinyl acetate, (meth)acrylic acid alkyl esters (such as methyl methacrylate, ethyl acrylate, n-butyl acrylate, and 2-acrylic acid).
non-functional monomers (C-1) such as (ethylhexyl) and ethylenically unsaturated carboxylic acids such as (meth)acrylic acid;
Hydroxyalkyl ester of meth)acrylic acid; glycidyl (meth)acrylate, β-(meth)acrylate
Epoxy group-containing unsaturated polymers such as 3,4-epoxycyclohexyl)methyl and allyl glycidyl ether
It is preferable to use it in appropriate combination with a functional monomer (C-2) such as N-butoxymethylacrylamide in order to carry out the crosslinking reaction of component CB).

Emulsion polymerization: The composition ratio of each component (A), (B), and (C) can be arbitrarily selected depending on the desired characteristics of the resulting polymer emulsion, but first, component (B) and (C) In terms of dispersion stability, etc., the components are (B) component/(C) component - 5/95 to 75/25, based on the solid content weight ratio, especially IO/
It is preferable and convenient to have a range of 90 to 50,150, especially 20
/80 to 40/60 (weight ratio) is preferable.

Further, an organic solvent may be added as appropriate to the mixture of components (B) and (C) in an amount of 50% by weight or less to adjust the solubility and viscosity of the mixture.

Component (A) should be used in an amount of 0.2 to 5% by weight, especially 0.5 to 3% by weight, based on the total weight of components CB) and (C) to improve dispersion stability and coating performance. Preferable from this point of view.

Further, as the polymerization initiator for component (C), known radical polymerization initiators such as benzoyl peroxide and azobisisobutyronitrile can be used. Among these, water-soluble hydrogen peroxide, ammonium persulfate, t-butyl hydroperoxide, 1-/tilperoxymaleic acid, succinic acid peroxide, 2,2'-azobis(N-hydroxyethylisobutyramide), and the like are preferred.

Furthermore, a redox initiator in which the peroxide is combined with a reducing agent such as sodium bisulfite, sodium thiosulfate, sodium hydroxymethanesulfinate, cuprous salt, or ferrous salt can be advantageously used.

The method of the present invention is carried out by emulsion polymerization using the components (A) to (C) described above by a method known per se. For example, the reaction temperature is below the reaction temperature of component (B) and component (C), for example 0-100°C, especially 30-90°C.
The temperature is preferably within the range of 0.degree. C., and component (C) containing component (B) is emulsion polymerized in the presence of component (A) and a polymerization initiator in an aqueous phase under an inert gas atmosphere.

Methods for adding the polymerization initiator and a mixture of components (B) and (C) include methods of adding the entire amount at the start of polymerization, methods of adding continuously as the polymerization progresses, and methods of adding part of the mixture after making a seed polymer. In addition, methods for adding component (A) include adding the entire amount before polymerization, and adding a portion to (B) # minutes, (C) t, minutes, and after emulsifying with water. There are various methods of adding, which can be selected as appropriate.

The emulsion obtained by the method of the present invention can not only be used alone in, for example, a water-based baking paint, but also one with a high crosslinking material content can be used as a curing agent for other aqueous resin dispersions.

Further, as a coating method when used in a paint, spray coating, roll coating, shower coating, electrodeposition coating, dipping coating, etc. can be used.

EXAMPLES Next, the present invention will be described in more detail with reference to Examples, but the present invention is not limited only to these Examples. Note that parts and percentages are basically based on weight.

Example 1 250 g of deionized water was charged into an IQ flask equipped with a reflux condenser, stirring period, dropping (0-), nitrogen inlet, and thermometer, the system was replaced with nitrogen gas, and the temperature was heated to 70°C in a water bath. Warm up. Allyl group-containing anionic surfactant Lamutil S-18O
2 g of A (Kao Corporation product, 50% aqueous solution) and 0.4 g of a 70% aqueous solution of 7-butylbaitolova-oxide were charged, and to this was added a crosslinking agent-containing monomer mixture lo having the following composition.
ng and 50 g of an aqueous solution of 0.3 g of sodium hydroxymethylsulfinate were separately added dropwise over 1 hour. After dropping, it was further aged at 70℃ for 1 hour, and the solid content was 24.2
%, a polymerization conversion rate of 96%, and a stable emulsion with an average particle size of 0,012 μm was obtained.

Composition: Styrene 20g Butyl acrylate 20g Methacrylic acid 10g Trimethylolpropane triglycidyl ether 50g When this is applied to a steel plate and baked at 140°C for 30 minutes, a hard coating film with excellent solvent resistance and adhesion is obtained. Ta.

Example 2 250 g of deionized water was placed in a lQ7 flask similar to Example 1, and after purging with nitrogen gas, the temperature was raised to 90°C, and allyl group-containing quaternary ammonium salt cationic surfactant, Nucor RF755 (Japan) 2 g of Emulsifier Co., Ltd. product) was charged, and to this was added 100 g of the following crosslinking agent-containing mixture and 50 g of an aqueous solution of 0.8 g of a water-soluble azoamide initiator, VA-086 (Wako Tsumugi Co., Ltd. product). Dropped over 1 hour, further aged at 90℃ for 1 hour, solid content 25.3
%, a polymerization conversion rate of 99%, and a stable emulsion with an average particle size of 0.08 μm were obtained.

Blend: 48 g of styrene, 20 g of 2-ethylhexyl acrylate, 12 g of methacrylic acid, 20 g of hexane carboxylate This was applied to a tin plate and baked at 160°0 for 20 minutes to obtain a hard, solvent-resistant film.

Example 3 350 g of deionized water was charged into a TC flask similar to that in Example 1, and after purging with nitrogen gas, the temperature was raised to 70°C, and allyl group-containing anionic surfactant, 50% Ramuthyl S5-18 was added.
OA4 and its nonionic surfactant Neugen H-3355
N (product of Daiichi Kogyo Seiyaku Co., Ltd.) Ig and 0.5 g of a 70% aqueous solution of t-butyl hydroperoxide were charged, and to this was added 100 parts of a heptamine mixture containing a crosslinking agent and sodium hydroxymethyl sulfinate having the following composition. 0.3 aqueous solution was separately added dropwise over 40 minutes, and further heated to 70°C.
Aged for 90 minutes, solid content 19.7%, polymerization conversion rate 9.
A stable emulsion of 7% and an average particle size of 0.20μ was obtained.

Blend: 40 g of methyl methacrylate 30 g of 2-ethylhexyl acrylate 10 g of acrylic acid 20 g of bisphenol A diglycidyl ether Add 2 parts of triethylamine to this, spray paint on a chromic acid-treated galvanized steel sheet, and bake at 130°C for 20 minutes to make it solvent resistant. A coating film with good adhesion was obtained.

Example 4 In a lQ7 flask similar to Example 1, add 250 g of deionized water.
The system was purged with nitrogen gas and heated to 60°C in a water bath. Sulfosuccinic acid allyl ester anionic surfactant, Ramuthyl s-tgOA (Kao Corporation product) 50
% aqueous solution 4 g and t-butyl hydroperoxide 70
% aqueous solution, 100 parts of a 7-mer mixture containing a crosslinking agent with the following composition and 50 g of an aqueous solution of 0.25 g of ammonium bisulfite were separately added dropwise over 1 hour, and further aged at 60°C for 2 hours. An emulsion having a solid content of 25.1%, a polymerization conversion rate of 99%, and an average particle size of 0.17 μm was obtained.

Blend: Styrene 30g n-butyl acrylate 25g 2-hydroxyethyl methacrylate 17g Michal Co., Ltd. product) 25g Spray paint on a tin plate and bake at 170°C for 20 minutes to create a hard, solvent-resistant coating. A membrane was obtained.

Example 5 A monomer mixture containing a crosslinking agent having the following composition was emulsion polymerized in the same manner as in Example 4 to obtain an emulsion with a solid content of 20.5%, a polymerization conversion rate of 100%, and an average particle size of 0.20μ. .

Composition: Styrene 25g 2-ethylhexyl acrylate 25g acrylic acid 2-
Hydroxyethyl 20g Acrylic acid g (Product of Hitachi Chemical TR Co., Ltd.) 40g Example 6 300g of deionized water was charged into an IQ7 flask similar to that in Example 1, and after purging with nitrogen gas, the temperature was raised to 80°C to remove allyl groups. A quaternary ammonium salt-based cationic surfactant containing 3 g of 1180Ac (manufactured by Kao Corporation) was added to Ramuthyl, and the following monomer mixture containing a polymerization initiator and crosslinking agent 1 was added to it.
01g was added dropwise over 1 hour and further aged at 70°C for 2 hours to obtain a stable emulsion with a solid content of 24.9%, a polymerization conversion rate of 99%, and an average particle size of 0.21μ.

Blend: 0 g of styrene, 0 g of n-butyl acrylate, 20 g of xime adduct, 0.5 g of dibutyltin dilaurate, 0.5 g of t-butyl hydroperoxide, and when spray-painted on a tin plate and baked at 160°C for 20 minutes, it becomes flexible and solvent-resistant. A coating film with good properties was obtained.

Comparative Example 1 When the surfactant in Example 1 was replaced with allyl group-free Nucor 271A (manufactured by Nippon Nyukazai Co., Ltd.),
The mixture of crosslinking agent and monomer is about 1/1.

When added dropwise, it aggregated.

Comparative Example 2.6 When the surfactant in Example 2.6 was replaced with allyl group-free Cortamine 86P (manufactured by Kao Corporation), some sedimentation occurred after polymerization.

Comparative Example 3 In Example 3, the surfactants were Allyl group-free Neogen R and Neugen EA-120 manufactured by Daiichi Kogyo Seiyaku (both Daiichi Kogyo Seiyaku).
Co., Ltd.), it separated after polymerization.

Comparative Example 4.5 Nucor 70 without allyl groups in Polymer 4.5
When it was replaced with 75F (manufactured by Nippon Nyukazai Co., Ltd.), a large amount of aggregates were formed in both polymers.

Claims (4)

[Claims] (1) A crosslinking agent-containing emulsion polymer emulsion characterized in that (C) an ethylenically unsaturated monomer is emulsion polymerized in the presence of (A) an allyl group-containing surfactant and (B) a water-insoluble crosslinking agent. Production method. (2) The method according to claim 1, wherein component (A) is used in an amount of 0.5 to 3.0% by weight based on the total amount of components (B) and (C). (3) Component (B) is a polyepoxide compound, and (C
3. The method according to claim 1, wherein component ) contains a monomer having a carboxyl group. (4) Component (B) is a poly N-alkoxymethyl compound or a blocked polyisocyanate compound, and (C)
3. A method according to claim 1 or 2, characterized in that the component comprises a monomer having hydroxyl groups.