JPH08134308A - Aqueous emulsion and its production - Google Patents

Abstract

PURPOSE: To obtain an aqueous emulsion containing a specific copolymer emulsion having a ladder silicone structure as a protecting colloid, reduced in the amount of an organic solvent, and improved in coatability. CONSTITUTION: The aqueous emulsion of the polymer of a polymerizable compound uses as a protecting colloid the emulsion of a neutralized copolymer comprising (A) a ladder type polyorganosiloxane having polymerizable unsaturated groups preferably a polymer having a structure of the formula [2-30mol% of R1 and R2 is polymerizable unsaturated groups such as (meth)acrylic groups, and the other is 1-18C alkyl, 6-8C aromatic group; >=30mol% of R3 to R6 is alkylsilylated groups such as trimethylsilylated groups], (B) an unsaturated carboxylic acid and (C) a polymerizable unsaturated compound. The aqueous emulsion is obtained by solution-polymerizing the components A to C in the presence of a polymerization initiator in a hydrophilic organic solvent, neutralizing the polymer solution, dispersing the product in water, adding a polymerizable compound and a polymerization initiator to the obtained emulsion, and subsequently emulsion-polymerizing the mixture.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an aqueous emulsion excellent in weather resistance, stain resistance and adhesion, and a method for producing the same,
The aqueous emulsion has a wide range of applications such as coating resins (building materials, vehicles, structures, etc.), adhesives, fiber processing agents, paper processing agents, mortar admixtures.

[0002]

2. Description of the Related Art Acrylic emulsions containing a silicone skeleton are more water resistant, weather resistant, and more durable than paints, adhesives and various processing agents using ordinary acrylic emulsions.
It has already been recognized that it is excellent in terms of adhesion to a substrate (for example, JP-A-5-214277).
For this reason, it has been attempted to incorporate a silicone segment into the acrylic polymer skeleton, but the water resistance, weather resistance, and adhesion to the substrate can be improved with an increase in the compounding amount, but the polymer film becomes flexible. At the same time, there is a problem that the stain resistance is lowered, and the adhesive strength, especially the tensile shear strength is lowered.

On the other hand, the ladder silicone (polyorganosilsesquioxane) has a rigid molecule and is excellent in weather resistance, hardness and stain resistance, and the rigidity can be improved by introducing a ladder silicone structure into the polymer. It can be expected that the ladder silicone itself has no solubility in water, and it was difficult to prepare a polymer emulsion by a usual emulsion polymerization method, even for a ladder silicone having an acrylic group in its side chain. It is considered that, because of the mechanism of emulsion polymerization, a small amount of the monomer dissolves in water and diffuses, solubilizes in the emulsifier micelle, and starts emulsion polymerization, which cannot be the usual mechanism of emulsion polymerization. ing.

The present inventors have succeeded in producing an aqueous emulsion of a polymer having a ladder silicone structure, and filed an application for it before. Furthermore, there is a demand for the development of an aqueous emulsion in which the amount of an organic solvent used for a polymerizable compound polymer using this emulsion as a protective colloid is small and various functional functional groups are introduced into the molecule.

[0005]

From the viewpoints of global environment conservation and improvement of working environment, efforts have been made to reduce the amount of organic solvents used in paints or processing agents, or to use them as little as possible. Solvent-free and water-based are strongly demanded. It is an object of the present invention to provide an aqueous emulsion of a polymerizable compound polymer using an aqueous emulsion of a polymer having a ladder silicone structure as a protective colloid, in which the amount of an organic solvent used is further reduced and the coating ability is improved. .

[0006]

The present invention provides, as protective colloids, (1) ladder-type polyorganosiloxane having a polymerizable unsaturated group, (2) unsaturated carboxylic acid and (3).
Aqueous emulsion of polymer of polymerizable compound using emulsion of neutralized copolymer composed of polymerizable unsaturated compound, (1) ladder type polyorganosiloxane having polymerizable unsaturated group, (2) unsaturated carvone The acid and (3) the polymerizable unsaturated compound are solution-polymerized in the presence of a polymerization initiator in a hydrophilic organic solvent, and the copolymer solution is neutralized or dispersed in water while being neutralized. A method for producing an aqueous emulsion, characterized in that a polymerizable compound and a polymerization initiator are added to the emulsion to carry out emulsion polymerization, and a ladder-type polyorganosiloxane having a polymerizable unsaturated group has a total solid content of 0.5. ˜50% by weight and at least 30 mol% of the end groups of the polyorganosiloxane
The above object was achieved by developing a method for producing an aqueous emulsion in which is trialkylsilylated.

In the protective colloid of the present invention, (1) the ladder-type polyorganosiloxane having a polymerizable unsaturated group (hereinafter referred to as ladder silicone) has a ladder silicone structure,

Embedded image The side chains R ₁ and R ₂ contain an acrylic group, a methacrylic group, a vinyl group, and an allyl group, and among R ₁ and R ₂ ,
The content of the polymerizable unsaturated groups is 1 to 50 mol%, preferably 2 to 30 mol%, and the other groups are selected from C _{1 to} C ₁₈ alkyl groups and C _{6 to} C ₈ aromatic groups. It is a thing. Further, it is preferable that 30 mol% or more of the end groups of the ladder silicone of R ₃ , R ₄ , R ₅ and R ₆ are alkylsilylated such as trimethylsilyl, triethylsilyl and diethylmethylsilyl.

(2) The unsaturated carboxylic acid is selected from acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid and citraconic acid, and they may be used alone or in combination. An unsaturated acid anhydride such as maleic anhydride that is hydrolyzed to an unsaturated carboxylic acid can also be used as the unsaturated carboxylic acid.

As the polymerizable unsaturated compound (3), acrylic acid ester, methacrylic acid ester, vinyl ester, allyl ester, styrene and alphamethylstyrene can be used alone or in combination. Specifically, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, glycidyl (meth) acrylate,
Hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, 2-aminoethyl (meth) acrylate, vinyl acetate, vinyl propionate, vinyl laurate, vinyl stearate, vinyl versatate, allyl acetate, styrene, Alpha methyl styrene etc. can be illustrated. Incidentally, 5% by weight or less of (meth) acrylamide and a derivative thereof, such as methylol (meth) acrylamide and alkoxy (meth) acrylamide, may be copolymerized with the polymerizable unsaturated compound.

The hydrophilic solvent used for solution polymerization of the copolymer is selected from alcohols, ethylene glycol derivatives, propylene glycol derivatives and glycerin derivatives. Specifically, methyl alcohol, ethyl alcohol,
Isopropyl alcohol, butyl alcohol, butanediol, methoxybutanol; ethylene glycol and its monomethyl ether, monoethyl ether, monopropyl ether, monobutyl ether and its monoalkyl ether acetate; diethylene glycol and its methyl ether, ethyl ether, propyl ether, butyl ether and Its acetate; triethylene glycol and its methyl ether, ethyl ether,
Propyl ether, butyl ether and its acetate; Propylene glycol and its methyl ether, ethyl ether, propyl ether, butyl ether and its acetate; Dipropylene glycol and its methyl ether, ethyl ether, propyl ether, butyl ether and its acetate; Tripropylene glycol and its Examples thereof include methyl ether, ethyl ether, propyl ether, butyl ether and its acetate; glycerin monoacetate and the like. Of these, ethyl alcohol, isopropyl alcohol, ethylene glycol and its monomethyl ether, monoethyl ether or their acetates, propylene glycol and their monomethyl ether, monoethyl ether and their acetates are particularly effective.

As the base for neutralizing the polymer containing an acid obtained by copolymerization, a base such as an aliphatic amine, a nitrogen-containing heterocyclic compound, an aromatic amine or an inorganic alkali is used. For example, monoethylamine, diethylamine, triethylamine, monopropylamine, dipropylamine, tripropylamine, monobutylamine, dibutylamine, tributylamine, monoethanolamine, diethanolamine, triethanolamine, dimethylaminoethanol, aniline, dimethylaniline, cyclohexylamine. , Pyridine, sodium hydroxide, potassium hydroxide, ammonium hydroxide and the like can be used, but diethylamine, triethylamine, triethanolamine, dimethylaminoethanol, alkali hydroxide and the like are particularly suitable.

A copolymer (1) ladder silicone,
The compounding ratio of (2) unsaturated carboxylic acid and (3) polymerizable unsaturated compound is 1 to 50: 1 to 30:30 to 98 (total weight is 1
00), preferably 2-30: 3-20: 50-
95, more preferably 2.5-25: 5-15: 60-
It is 92.5. (1) If the ladder silicone content is less than this range, the water resistance, weather resistance and stain resistance will be insufficient, and if it is more than this range, gelation may occur during the polymerization operation. (2) When the amount of unsaturated carboxylic acid is less than this, a stable emulsion is not formed even if the neutralized product is put in water,
If it is more than this, the water resistance decreases. (3) The proportion of the polymerizable unsaturated compound is determined by the proper ratio of (1) and (2).

The emulsion (protective colloid or seed emulsion) thus obtained may be subjected to emulsion polymerization by adding or removing a solvent, if necessary, and then adding a polymerizable compound and a polymerization initiator. A polymerized emulsion of is obtained. The molecular weight of the polymer containing the ladder silicone obtained here is not particularly limited, but a polymer having a molecular weight of about 1,000 to 100,000 is easily obtained. The polymerizable compound used in this second-stage polymerization is the same as the monomers used in the production of ordinary polymer emulsions, and the polymerizable compounds used in the seed emulsion (2) and (3) are not changed. The same types of compounds as listed in the saturated compound can be used, and it is also possible to use the same or a plurality of polymerizable monomers. In particular, when the type of the polymerizable compound is appropriately selected and used, the low glass transition temperature T of the seed emulsion polymer is obtained.
It is also possible to make a so-called shell-core emulsion in which the g is increased, or conversely, the high glass transition temperature Tg of the seed emulsion polymer is decreased.

The amount of the polymerizable compound (polymerizable monomer, etc.) to be added is suitably 0.1 to 10 parts by weight, preferably 0.1 to 10 parts by weight based on 1 part by weight of the solid content in the seed emulsion.
It is 3 to 8 parts by weight, more preferably 0.5 to 5 parts by weight. This amount is appropriately determined depending on the purpose in order to bring out the performance in applying the emulsion. The polymerization initiator to be used may be a persulfate, hydrogen peroxide, sodium perborate, t-butyl hydroperoxide or the like which is commonly used in emulsion polymerization. A redox polymerization initiator using a reducing agent as the oxidizing agent can also be used. Of these, water-soluble persulfates and hydrogen peroxide are preferable. Emulsion polymerization can be performed in the same manner as ordinary emulsion polymerization, and additives such as emulsifiers and plasticizers used in emulsion polymerization can also be used.

The polymerizable compound polymer contained as the solid content of the obtained aqueous emulsion is one in which the newly added polymerizable compound is chemically bonded (graft-polymerized) to the polymer of the seed emulsion. It is considered that there are those in which a polymer is separately formed on the surface of the emulsion polymer, or those which exist as a homopolymer of itself in the dispersion medium, and the molecular weight thereof is not limited, but 1 It is in the range of 1,000 to 600,000. Finally, the ladder siloxane is polymerized to 0.5 to 50% by weight, preferably 1 to 40% by weight, based on the total solid content in the aqueous emulsion.

A hydroxyl group, a glycidyl group, an amino group, an amide group, a methylol group, an alkoxymethylolamide group, an acetylacetonate group or the like is added to either or both of the polymerizable unsaturated compound used for the seed emulsion and the polymerizable compound used for emulsion polymerization. When the functional group (1) is contained, it can be crosslinked with a carboxyl group, which is an essential component of the present invention, using a suitable crosslinking agent. As the cross-linking agent, one that is compatible with the above-mentioned reactive groups is selected, and for example, in the case of an aqueous emulsion having a hydroxyl group, it is cross-linked by the addition of a melamine resin initial condensate, isocyanate or the like.
When isocyanate is used as a cross-linking agent, blocked isocyanate is used, or a high-boiling solvent that is immiscible with water is dissolved and added to disperse. The copolymer having a carboxyl group can be crosslinked with a polyfunctional glycidyl compound, a polyvalent metal salt, a polyvalent amine, or the like.

The aqueous emulsion of the present invention forms a tough film having water resistance, weather resistance, adhesion and stain resistance when it is applied or impregnated on a substrate and then dried, so that a coating agent (metal, ceramic products , Coating materials for plastics, wood, hard coating agents, electrodeposition paints, etc., fiber processing agents (texture processing of fibers, nonwoven fabric binders, etc.), paper processing agents (internal additives, coatings, etc.), adhesives (metals) , Ceramic products, wood, paper, etc.) and mortar have a wide range of uses such as admixture with cement to reduce the water absorption.

[0018]

The emulsion of the present invention is an aqueous emulsion of a polymerizable compound, which is the first polymer emulsion containing a ladder-type polyorganosiloxane structure to be used as a protective colloid. Therefore, as the protective colloid, a neutralized polymer emulsion of (1) a ladder-type polyorganosiloxane having a polymerizable unsaturated group, (2) an unsaturated carboxylic acid and (3) a copolymer of a polymerizable unsaturated compound is used. In this case, as the polymerizable unsaturated compound (3), not only the physical properties of the target polymer but also the most advantageous monomer for producing an emulsion may be selected.
Emulsion polymerization of the target polymerizable compound using the emulsion thus obtained as a protective colloid makes it possible to easily obtain an aqueous emulsion of the target polymerizable compound having a ladder-type polyorganosiloxane structure at an appropriate concentration. .

Also, by selecting a combination of the polymerizable compound different from that of the seed emulsion, it becomes possible to arbitrarily select the performance such as the glass transition temperature Tg of the polymer of the aqueous emulsion, and to produce a so-called shell-core emulsion. Will also be possible. As described above, even if the polymerizable compound is arbitrarily selected, it is possible to obtain a film having a high hardness without losing the properties peculiar to silicone-containing such as water resistance, weather resistance, adhesion, gloss and stain resistance.

[0020]

【Example】

(Synthesis example 1) 2 equipped with a thermometer, a stirrer, and a reflux condenser
In a liter flask, 50 g (0.2 mol) of 3-methacryloxypropyltrimethoxysilane, 445 g (2.5 mol) of methyltriethoxysilane, 20 g (0.1 mol) of phenyltrimethoxysilane, 0.002 mol of hydrochloric acid, 108 g (6 mol) of water was charged, the temperature in the flask was raised to 60 ° C., and the mixture was kept for 5 hours while stirring. Subsequently, the temperature is raised to 70 ° C. and the reaction is carried out for 1 hour, then 0.004 mol of potassium hydroxide dissolved in methanol is added dropwise and the reaction is continued for another 4 hours. After neutralization with hydrochloric acid, toluene was added and the mixture was washed with water, the solvent and water were removed using a rotary evaporator, and the precipitated salt was filtered off. The product had a viscosity at 25 ° C. of 2,850 cp and a methacryloxy group content of 7.
It was 1 mol% and the number average molecular weight was 6,200. The terminal of this compound is a hydroxyl group and an alkoxy group, and when left alone, the terminals react with each other and are easily gelated.
The reaction was carried out at 5 for 1 hour, and a part of the terminal groups was changed to trimethylsilyl groups to make the total number of terminal hydroxyl groups and alkoxy groups 1.5 per molecule. This is called siloxane A.

2 equipped with a thermometer, a stirrer, and a reflux condenser
In a liter flask, 500 g of ethylene glycol monomethyl ether and 4 g of azobisisobutyronitrile as a polymerization initiator were put and dissolved by stirring, and the temperature was raised to 70 ° C., 30 g of siloxane A, 100 g of styrene, 100 g of methyl methacrylate, butyl acrylate. A mixed solution of 150 g, methacrylic acid 50 g, and hydroxyethyl methacrylate 20 g was added over 1 hour. The temperature was further raised to 100 ° C. and kept for 5 hours to complete the polymerization. After cooling to room temperature and adding 59 g of trimethylamine for neutralization, a resin solution containing a ladder silicone having a solid content of 47% was obtained. An emulsion was prepared by adding 200 g of deionized water to 100 g of this solution with vigorous stirring. The obtained emulsion has a solid content concentration of 18%, a viscosity at 25 ° C. of 970 cp, and an average particle diameter of 0.2 μ.
m, and the polymer Tg was 9 ° C.

Next, 300 g of the above seed emulsion was placed in a 1 liter flask equipped with a thermometer, a stirrer and a reflux condenser.
Then, 12 g of a 10% aqueous solution of ammonium persulfate was added and mixed with stirring, the temperature was raised to 70 ° C., and a monomer having the following composition was added dropwise over 1 hour. Then, the temperature was kept at 100 ° C. for 5 hours to complete the polymerization. Monomer Methyl methacrylate 150 g 2 Ethylhexyl acrylate 50 g Methacrylic acid 10 g Glycidyl methacrylate 15 g The resulting emulsion had a solid content concentration of 48% and a particle size of 0.
8 μm, viscosity 5,800 cp, Tg of polymer is 13 ° C
Met.

(Synthesis Example 2) 30 g (0.2 mol) of vinyltrimethoxysilane, 445 g (2.5 mol) of methyltriethoxysilane and phenyl were placed in a 2 liter flask equipped with a thermometer, a stirrer and a reflux condenser. Trimethoxysilane 20 g (0.1 mol), hydrochloric acid 0.002 mol, water 10
8 g (6 mol) was charged, the temperature in the flask was raised to 60 ° C., and the mixture was kept for 5 hours while stirring. Subsequently, the temperature was raised to 70 ° C. and the reaction was carried out for 1 hour, then 0.004 mol of potassium hydroxide dissolved in methanol was added dropwise, and the reaction was carried out for another 4 hours. After neutralizing with hydrochloric acid, add toluene and wash with water, and then use a rotary evaporator to remove the solvent and water.
The salt that precipitated was filtered off. The product has a viscosity of 3,2 at 25 ° C.
00 cp, vinyl group content was 7.5 mol%, and number average molecular weight was 3,400. The terminal of this compound is a hydroxyl group and an alkoxy group, which easily gels when left standing.
g was added and the mixture was reacted at pH 5 for 1 hour, part of the terminal groups was changed to trimethylsilyl groups, and the total number of hydroxyl groups and alkoxy groups at the terminals was 0.9 per molecule. This is called siloxane B.

2 equipped with a thermometer, a stirrer, and a reflux condenser
In a 1-liter flask, 600 g of propylene glycol monoethyl ether and 5 g of azobisisobutyronitrile as a polymerization initiator were put and dissolved by stirring, and the temperature was raised to 70 ° C., and 80 g of siloxane B, 100 g of methyl methacrylate, 300 g of butyl acrylate, and methacryl A mixed solution of 60 g of acid was added dropwise over 1 hour. The temperature was further raised to 100 ° C., and the temperature was maintained for 5 hours to complete the polymerization. Then cool to room temperature and add 42 g of monopropylamine to neutralize,
This was poured into 1200 g of water with vigorous stirring. The produced emulsion has a solid content concentration of 23.1% and a viscosity of 1.
It was 100 cp, the average particle diameter was 0.3 μm, and the Tg of the polymer was −6 ° C.

1 equipped with a thermometer, a stirrer, and a reflux condenser
300 g of the above seed emulsion was placed in a 1-liter flask, 12 g of an aqueous solution of 10% ammonium persulfate was added and mixed with stirring, the temperature was raised to 70 ° C., and a monomer having the following composition was added dropwise over 1 hour. Then, the temperature was kept at 100 ° C. for 5 hours to complete the polymerization. Monomer Methyl methacrylate 140 g 2 Ethylhexyl acrylate 20 g Methacrylic acid 10 g Glycidyl methacrylate 15 g The resulting aqueous emulsion has a solid content concentration of 51.3%, a particle diameter of 1.0 μm, a viscosity of 9,600 cp, and a polymer Tg.
Was 10 ° C. Although the application examples have been shown for paints and adhesion, the application is not limited to this.

(Application Example 1) 100 parts of the aqueous emulsion produced in Synthesis Example 1, butyl carbitol acetate 3
Parts, 15 parts of titanium white kneaded with 80 parts of an aqueous dispersant solution,
0.5 part of a fluorine-based defoaming agent and 10 parts of a 3% aqueous solution of methyl cellulose were placed in a paint shaker and stirred for 3 hours to prepare a uniform dispersion liquid. To this, 3 parts of the water-soluble melamine resin initial condensate was added, stirred and dispersed to obtain a coating liquid. Apply this coating solution to a steel plate coated with an epoxy primer to a dry thickness of 1
It was spray-coated so as to have a thickness of 5 μm, dried at 80 ° C. for 5 minutes, and then heated at 150 ° C. for 10 minutes to finish. The test results of the coating film are shown in Table 1.

(Application Comparative Example 1) With the formulation of Synthesis Example 1,
Table 1 shows the test results of the coating film using the emulsion prepared by omitting the siloxane A. As can be seen from the table, the hardness, gloss and weather resistance were inferior to those of Application Example 1.

[0028]

[Table 1] 1) According to JIS K5400 2) Same as above 3) Same as above 4) Sunshine weather meter according to JIS D0205 State after 3000 hours

(Application Example 2) Wood was adhered using the aqueous emulsion synthesized in Example 2. Laminate the birch material,
A tensile test was carried out according to JIS K6851 (wood tensile shear adhesive strength test method for adhesives). Ie lap length 1
150 g of emulsion in a birch material with a width of 3 mm and a width of 25 mm
/ M ² and applied at 30 ° C. for 24 hours,
An adhesion test was carried out after leaving at 20 ° C. and 65% RH for 24 hours. For water resistance test, after soaking in water at 30 ℃ for 3 hours, 2
It was immersed in 0 ° C. water for 10 minutes and tested in the wet condition. Table 2 shows the results.

(Application Comparative Example 2) Using an emulsion produced by omitting siloxane B in Synthesis Example 2,
The same wood adhesion test as in Application Example 2 was performed. Compared to Application Example 2, the adhesive strength was low both in the normal state and after immersion in water.

[0031]

[Table 2]

[0032]

The present invention relates to an aqueous emulsion obtained by emulsion-polymerizing a polymerizable compound using an emulsion containing a ladder silicone as a protective colloid, and has a glass transition temperature Tg of the protective colloid polymer.
A shell-core emulsion that can be freely converted to a desired temperature can be easily produced. Further, since the aqueous emulsion containing ladder silicone is used as the protective colloid, the ladder silicone-containing aqueous emulsion could be produced without newly adding an organic solvent, while maintaining the performance peculiar to the ladder silicone. The aqueous emulsion of the present invention has a rigid molecule, weather resistance,
Since it contains a ladder silicone with excellent hardness and stain resistance, a film with excellent water resistance, weather resistance, adhesion to substrates, stain resistance, hardness, etc. is formed.
It has a wide range of applications such as adhesives, fiber processing agents, paper processing agents, mortar admixtures, and protective colloids for emulsion polymerization.

Front page continuation (72) Inventor Masami Matsuoka 1-1-1 Onodai, Midori-ku, Chiba-shi, Chiba Showa Denko K.K.

Claims (3)

[Claims] 1. As a protective colloid, (1) a ladder-type polyorganosiloxane having a polymerizable unsaturated group, (2)
An aqueous emulsion of a polymerizable compound polymer using an emulsion of a neutralized copolymer comprising an unsaturated carboxylic acid and (3) a polymerizable unsaturated compound. 2. A hydrophilic polyorganosiloxane having (1) a ladder-type polyorganosiloxane having a polymerizable unsaturated group, (2) an unsaturated carboxylic acid and (3) a polymerizable unsaturated compound in the presence of a polymerization initiator. The solution is characterized in that it is subjected to solution polymerization in order to neutralize the copolymer solution, or while being neutralized and dispersed in water, an emulsion obtained by adding a polymerizable compound and a polymerization initiator to emulsion polymerization. Emulsion manufacturing method. 3. A ladder-type polyorganosiloxane having a polymerizable unsaturated group contains 0.5 to 50% by weight of the total solid content, and at least 30 mol% of the end groups of the polyorganosiloxane are trialkyl. The method for producing an aqueous emulsion according to claim 2, which is silylated.