JPH0619056B2 - Polymer coating method for inorganic solid substances - Google Patents

Description

TECHNICAL FIELD The present invention relates to an improvement in a method for coating an inorganic solid substance with a polymer.

[Prior Art] An inorganic solid substance coated with a polymer is considered to be applied to various fields depending on the type of polymer to be coated and the type of solid substance to be coated. For example, fillers typified by calcium carbonate, silica, clay, etc. are used in large quantities as fillers for rubber, plastics, paints, papermaking and the like. At that time, since these fillers are inorganic substances, they have a low affinity with organic substances such as rubber and plastic to be kneaded, and for this reason, various measures have been taken. These one
As one method, making the surface of the filler lipophilic is considered,
Actually, surface treatment with a silane coupling agent or the like is performed. However, the actual situation is that satisfactory results have not been obtained even with such processing. Also,
By further developing the above ideas, we will further enhance the functions of these fillers by developing plastic beads with a filler core, molding by integrating plastic and filler, or developing a polymer emulsion with a filler core. Attempts have been made to do so.

On the other hand, focusing on the excellent properties of the inorganic powder as a base, such as porosity, pressure resistance, and chemical resistance, by coating a polymer having a special function on the base of these bases, new functionality can be obtained. The idea of developing a material has been proposed, and a test for producing a molded product or emulsion having a function not obtained by the conventional method by coating a surface of a polymer particle with a different polymer has been conducted.

In recent years, a method for coating a solid substance by contacting a monomer having a radically polymerizable unsaturated bond and a polymerization developer in the presence of an organic sulfonic acid having a vinyl group or a salt thereof has been disclosed in Japanese Patent Publication No. 54-8548 and It is disclosed in JP-A-57-115412. However, in those methods, the monomers actually used are mainly methyl methacrylate (hereinafter referred to as MMA).
Abbreviated) and the applied solid substance is not versatile and has not been sufficiently practical.

In view of the above points, as a result of the inventors' earnest studies,
It was found that the inorganic solid substance can be easily coated with a polymer by forming a salt of a quaternary ammonium compound and an inorganic compound having a polymerization initiating ability on the inorganic solid substance and initiating polymerization. .

[Object of the Invention]

An object of the present invention is to provide a method of coating an inorganic solid substance with a polymer using a salt of a quaternary ammonium compound and an inorganic compound having a polymerization initiation ability.

[Disclosure of Invention]

The above object of the present invention is achieved by the following method for coating an inorganic solid substance with a polymer.

An inorganic solid substance characterized by forming a salt of a quaternary ammonium compound and an inorganic compound having a polymerization initiation ability on an inorganic solid substance, and then initiating the polymerization of a monomer having a radically polymerizable unsaturated bond. Coating method with polymer of.

[Best Mode for Carrying Out the Invention]

The present invention is characterized in that a salt of a quaternary ammonium compound and an inorganic compound having a polymerization initiating ability is formed on an inorganic solid substance, and the type of monomer to be polymerized and the inorganic solid substance to be coated. By changing the kind of the above, it is possible to obtain an inorganic solid substance coated with various polymers.

The quaternary ammonium compound used in the present invention can be used in a very wide range, but among them, those having relatively high hydrophobicity are preferable. Specific examples thereof include a cationic surfactant type monomer having a micelle forming ability, a cationic surfactant and those having a structure similar to that. As a more specific cationic surfactant type monomer having a micelle forming ability, (In the formula, R ₁ is hydrogen or a methyl group, R ₂ is a lower alkyl group, preferably an alkyl group having 1 to 2 carbon atoms, and R ₃ is a long chain alkyl group having 6 to 24 carbon atoms, preferably 8 to 16 carbon atoms. ,
Y is an -O- group or an -NH- group, n is a positive integer of 2 to 8,
X is halogen. ) A long-chain alkyl quaternary salt of an acrylate or methacrylate type (hereinafter abbreviated as (meth) acrylate type) cationic monomer and an acrylamide or methacrylamide type (hereinafter abbreviated as (meth) acrylamide type) cationic monomer 1 type or 2 or more types.

To illustrate the above monomers in the form of tertiary amines first,
In the (meth) acrylate type, for example, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, dimethylaminobutyl (meth) acrylate, dimethylaminohexyl (meth) acrylate, dimethylaminooctyl. Examples thereof include (meth) acrylate, dimethylaminopropyl (meth) acrylamide, diethylaminopropyl (meth) acrylamide and the like. Those obtained by quaternizing these tertiary amine monomers with a long-chain alkyl halide having 6 to 24 carbon atoms correspond to the above general formula. In the above general formula, R ₃ is a dodecyl group and X is a bromine. For example, when fixed, (meth) acryloyloxyethyldimethyldodecyl ammonium bromide, (meth) acryloyloxyethyl diethyl dodecyl ammonium bromide, (meth) acryloyloxypropyl dimethyl dodecyl ammonium bromide, (meth) acryloyloxybutyl dimethyl dodecyl ammonium Bromide, (meth) acryloyloxyhexyl dimethyl dodecyl ammonium bromide,
Examples thereof include (meth) acryloyloxyoctyldimethyldodecylammonium bromide, (meth) acrylamidopropyldimethyldodecylammonium bromide, and (meth) acrylamidopropyldiethyldodecylammonium bromide.

Next, the cationic surfactant may be a compound having a long-chain alkyl chain and a quaternary ammonium group substituted in the molecule, and may be an aliphatic quaternary ammonium salt, a benzalkonium salt, a pyridinium salt, or an imidazolium salt. Examples of such salts include a nickel salt.

The aliphatic quaternary ammonium salt is represented by the following general formula, R ₁ is a linear alkyl group having 12 to 18 carbon atoms, R ₂ is a methyl group or a linear alkyl group having 12 to 18 carbon atoms, and X is a chlorine or bromine atom. The benzalkonium salt is an alkyldimethylbenzylammonium salt represented by the following general formula, R is a straight-chain alkyl group having 12 to 24 carbon atoms and X is a chlorine or bromine atom. The pyridinium salt is an alkylpyridinium salt represented by the following general formula, R is a linear alkyl group having 12 to 18 carbon atoms and X is a chlorine or bromine atom. The imidazolinium salt is represented by the following general formula, R is a linear alkyl group having 1 to 4 carbon atoms, R ₁ is a linear alkyl group having 12 to 24 carbon atoms, and R ₂ is 1 to 5 carbon atoms.
Is a straight-chain alkyl group, and X is a chlorine or bromine atom.

Further, as those having a structure similar to the above cationic surfactant, there are tetraalkylammonium salts often used in phase transfer reactions and the like, specifically, tetraethylammonium bromide, tetrapropylammonium bromide, tetrabutylammonium bromide. Phase transfer catalysts such as Among the above, cationic surfactant type monomers and cationic surfactants are preferable.

Next, as the inorganic compound having a polymerization initiation ability to form a salt with the above-mentioned quaternary ammonium compound, the kind thereof is extremely limited in that it has a polymerization initiation ability, and an alkali metal or ammonium persulfate or sulfurous acid is used. Hydrogen salt,
The only examples are sulfites. More specifically,
Examples of the persulfate include potassium persulfate, ammonium persulfate, sodium persulfate and the like, examples of the bisulfite include sodium bisulfite, potassium bisulfite, ammonium bisulfite and the like, and sodium sulfite as the sulfite, Examples thereof include potassium sulfite and ammonium sulfite.

Further, as the inorganic solid substance used as a place for forming a salt of a quaternary ammonium compound and an inorganic compound having a polymerization initiation ability, those having various shapes such as spherical, powdery, fibrous, plate-like, and scale-like Can be used. Specifically, simple metals, oxides, sulfides, nitrides, carbides, silicides,
There are borides, chlorides, phosphates, sulfates, sulfites, carbonates, silicates, hydroxides and mixtures thereof, double salts, intermolecular compounds and the like. Specifically, iron, copper, aluminum, alumina, red iron oxide, ferrite, cadmium sulfide, carbon nitride, boron carbide, zirconium silicide, calcium boride, silver chloride, aluminum phosphate, gypsum, calcium sulfite, calcium carbonate, There are aluminum hydroxide, silica gel, etc., and inorganic pigments such as titanium white, zinc white, yellow lead, cobalt blue, chrome green, white carbon, pearlite, asbestos, sand, mica, shirasu balloon, zeolite, talc, bentonite. Applicable to clay and other natural minerals.

According to the method of the present invention, a salt of the above-mentioned quaternary ammonium compound and an inorganic compound having a polymerization initiation ability is formed on an inorganic solid substance to initiate polymerization, but the quaternary ammonium compound and an inorganic compound having a polymerization initiation ability are formed. The salt composed of the compound generally has the following properties. The salt is rapidly formed by simply mixing the aqueous solution of the quaternary ammonium compound and the aqueous solution of the inorganic compound, and in many cases, the salt is precipitated from the aqueous solution. That is, the formation of the salt occurs by the metathesis reaction of the quaternary ammonium salt and the inorganic salt, and the salt is composed of the quaternary ammonium ion and the inorganic ion. Specifically 4
It is a combination of a primary ammonium ion and a persulfate ion, a hydrogen sulfite ion or a sulfite ion. The relative proportion of those ions at that time is preferably in a stoichiometric relationship as shown in Reference Example, but it is not always necessary to be bound by this relationship. However, when the proportion of inorganic ions increases, not only on the surface of the solid but also in the solution, the progress of polymerization occurs, and as a result, the proportion of the polymer to be coated decreases and efficiency deteriorates. On the other hand, when the ratio of the quaternary ammonium ion increases, micelles are formed in the solution, and the polymerization also proceeds there. As a result, the coating efficiency of the polymer decreases.

Therefore, it cannot be said uniformly about their ratio, but 4
The equivalent of the primary ammonium ion is preferably 0.25 to 2.0 equivalents, more preferably 0.50 to 1.5 equivalents.

Further, those salts are extremely stable, can be easily separated from water by centrifugation, etc., and can be dried. The solubility of these salts in various solvents such as water, methanol, acetone, N, N-dimethylformamide, tetrahydrofuran, ethyl acetate, chloroform, benzene, etc. changes with temperature, and the solubility changes with heating. To increase.

There are the following three methods for forming the above-mentioned salt on the inorganic solid substance. The first method is to suspend an inorganic solid substance in a medium and generate a salt there to form a salt on the inorganic solid substance. The second method is to add the above-mentioned salt to the medium. A method of forming a salt on the inorganic solid substance by dissolving it by a method such as heating and then adding an inorganic solid substance to the solution to lower the temperature is the third method. There is a method of coating or spraying on the inorganic solid substance and further evaporating the solvent to form a salt on the inorganic solid substance, and thus the surface of the inorganic solid substance is made hydrophobic. The quantitative ratio between the inorganic solid substance and the salt deposited on the surface thereof is largely influenced by the specific surface area of the solid substance, and the larger the specific surface area, the more easily the deposited amount can be increased. However, if the amount of deposition is too large, the subsequent polymerization will proceed rapidly,
Defects such as non-uniform coating are recognized.

Therefore, although the amount of deposition cannot be said to be uniform due to the difference in specific surface area and the like, the amount of salt deposition is generally in the range of 0.001 to 1.0 when the weight part of the inorganic solid substance is 1. Such a wide range of deposition amount is due to various cases depending on the purpose, such as coating a solid substance with an extremely thin polymer layer, producing plastic beads having a solid substance as a core, and the like. Is. Further, a salt may be formed by using two or more kinds of quaternary ammonium compounds and an inorganic compound having a polymerization initiation ability.

Next, there are two methods for initiating the polymerization using the above-mentioned surface-treated inorganic solid substance.

That is, there are two methods, that is, a method of suspending an inorganic solid substance in a medium to start the polymerization and a method of introducing a monomer vapor onto the inorganic solid substance to start the polymerization, but the former is easier to control the reaction. It is convenient in that respect. As a medium to be used at that time, water is generally mentioned, but methanol, acetone, N, N-dimethylformamide, tetrahydrofuran, ethyl acetate, chloroform, benzene and the like other than water, and a mixed solvent thereof with water are also used. Can be used.

The amount of the liquid medium added is usually 0.2 with respect to the volume of the solid substance.
˜1.000 times, preferably 0.5 to 500 times.

As the monomer having a radically polymerizable unsaturated bond, either a hydrophobic monomer or a hydrophilic monomer can be used.

Examples of the hydrophobic monomer include styrene, α-methylstyrene, vinyl acetate, vinyl chloride, acrylonitrile,
Ethyl acrylate, butyl acrylate, glycidyl acrylate, MMA butyl methacrylate, glycidyl methacrylate, N-propyl acrylamide, n-butyl acrylamide, n-octyl acrylamide, N-ethyl methacrylamide, N-butyl acrylamide, N, N −
Examples thereof include diglycidyl acrylamide, N-acryloylpyrrolidin, N-acryloylpiperidin, N-methacryloylpyrrolidin, ethylene, propylene, divinylbenzene, ethylene glycol dimethacrylate, divinyl ether, butadiene and chloroprene. Specific examples of the hydrophilic monomer include hydroxyethyl methacrylate, N-vinylpyrrolidone, acrylamide, N, N-
Dimethyl acrylamide, N-ethyl acrylamide,
Methacrylamide, acrylic acid or a salt thereof, methacrylic acid or a salt thereof, and the like.

The amount of the monomer added to the inorganic solid substance is 0.05 to 1.000% by weight, preferably 0.1 to 500% by weight. The addition amount in such a wide range is due to various cases such as the case where the solid substance is coated with an extremely thin polymer, the case where the plastic beads having the solid substance as the core are produced, and the like.

When starting the polymerization, the salt may be formed on the inorganic solid substance to start the polymerization in the presence of the monomer, or the monomer may be added after the salt is formed on the inorganic solid substance. Then, the polymerization may be started. During the polymerization, it is better to stir to improve the dispersion of the inorganic solid substance.

The polymerization is preferably carried out in an atmosphere containing no oxygen such as nitrogen gas, but when bisulfite or sulfite is used as the inorganic salt, oxygen coexisting may exhibit a catalytic action. Further, the polymerization temperature is in the range of 30 to 90 ° C when a persulfate is used as the inorganic salt, and the polymerization temperature can be lowered to 0 ° C or lower by combining it with a reducing agent. Examples of the reducing agent used therein include sulfite, bisulfite, salts of low ionic value such as iron, copper and cobalt, organic amines such as aniline, and reducing sugars such as aldose and ketose. You can

When the inorganic solid substance is coated with one or more polymers by the above-mentioned method, the process of the polymerization can be performed by changing the appearance of the dispersed solid substance or quantifying the residual monomer by gas chromatography or the like. . Also, after polymerization for a predetermined time, the reaction mixture is passed, by a method such as centrifugation,
It is also possible to obtain a solid substance which is separated and coated with a polymer. On the other hand, the liquid may be discarded or may be recycled.

〔The invention's effect〕

In the case of the present invention, since a salt of a quaternary ammonium compound and an inorganic compound having a polymerization initiation ability is formed on an inorganic solid substance to initiate polymerization, the surface of the inorganic solid substance is hydrophobized and a single amount thereof is present there. Since body adsorption occurs and polymerization starts on the surface, it is possible to selectively polymerize only on the surface, and because the surface is ionized, the particles are stable due to ionic repulsion. Can be dispersed.

As a result, the polymerization on the surface of the solid substance can be rapidly and uniformly proceeded, and the ratio of the polymer coating the solid substance can be easily controlled, so that a new functional material can be formed by combining different materials. It will be a necessary technology for development.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 A column chromatography silica gel (15
(0-200 mesh) 1.0 g and potassium persulfate 0.054 g are added at room temperature and thoroughly stirred, and then methacryloyloxyethyl dimethyldodecyl ammonium bromide (hereinafter, C
Abbreviated as ₁₂ Br. 5 ml of an aqueous solution in which 0.24 g was dissolved was added while sufficiently stirring the above aqueous solution. Then, 0.50 g of methyl methacrylate (hereinafter abbreviated as MMA) was added. The aqueous solution was freeze-deaerated, replaced with a nitrogen atmosphere, and then polymerized while stirring in a constant temperature bath at 50 ° C. for 24 hours. Then, an aqueous solution of cuperone was added to the polymerization solution to terminate the polymerization, the polymerization mixture was centrifuged at 3,000 rpm for 10 minutes, the precipitate and the supernatant were separated, and the precipitate was mixed with water and centrifuged for several minutes. Repeatedly washed. The supernatant liquid and the washing liquid were combined, and 10% sodium bromide aqueous solution was added thereto to salt out the latex polymer, and the precipitated polymer was separated, washed with water, dried and weighed. 4.3 mg
(Yield 0.58%). When the precipitate was dried and weighed, it was 1.58 g, and the coated polymer yield was 0.58 g (78.2% yield).

When observing the surface of this thing with a scanning electron microscope,
It was confirmed that the surface was uniformly coated with the polymer.

Examples 2 to 9 Coating of a solid substance with a polymer was performed in exactly the same manner as in Example 1 except that the combination of inorganic solid substance, quaternary ammonium compound and monomer shown in Table 1 and the addition amount were used. It was The product was analyzed in exactly the same manner as in Example 1, and the results obtained are shown in Table 2.

The polymer-coated solid substance obtained in Example 2 was used to perform a surface wetting test, and the results are shown in Reference Examples.

Comparative Example 1 Polymerization and the subsequent treatment were carried out in the same manner as in Example 1 except that C ₁₂ Br was not added, and the yield of the precipitate was 1.00 g, coating with the polymer did not occur, and The formation of latex polymer was also slight.

Example 10 Methacryloyloxyethyl dimethyldodecyl ammonium bromide (hereinafter abbreviated as C ₁₂ Br) 0.24 in 20 ml of an aqueous solution in which 0.054 g of potassium persulfate was dissolved.
5 ml of an aqueous solution in which g was dissolved was added with stirring. Salt began to precipitate with addition. After the addition was completed, the mixture was heated to 60 ° C. to dissolve the precipitated salt, 1.0 g of silica gel was added thereto, and the mixture was slowly cooled to room temperature. MMA (1.00 g) was added to the cooled aqueous solution, and the polymerization and the subsequent treatment were carried out in the same manner as in Example 1. As a result, the yield of the precipitate was 2.02 g, the yield of the coating polymer was 82.3%, and the yield of the latex polymer was 0.00%.

Reference Examples 1-3 0.59 g of silica gel and C ₁₂ Br 0.163 in 19 ml of distilled water
(0.400 mmol) was added and sufficiently stirred, and then 1 ml of an aqueous solution in which 0.054 g (0.200 mmol) of potassium persulfate was dissolved was added, and the mixture was reacted at 25 ° C. for 1 hour. After the reaction, the precipitate was separated and dried and weighed. The liquids were also subjected to iodine titration to determine the amount of dissolved potassium persulfate.

As a result, potassium persulfate on silica gel was 86.0.
% In the solution was very small. Reaction and subsequent treatment were carried out in the same manner as in Reference Example 1 with the composition shown in Table 3, and the results shown in Table 3 were obtained.

Reference Example 4 Wetting Test One end of a glass tube having an inner diameter of 6 m / m was stoppered with quartz wadding, and the silica gel coated with the polymer obtained in Example 2 was filled therein and immersed in a water bath at 22 ° C. The position of the water surface rising in the glass tube was measured from the lower end, and the measurement results every 2 hours are shown in Table 4. Simultaneously, using silica gel as a raw material, wetting was measured in exactly the same manner, and the results are shown in Table 4.

Claims (2)

[Claims] 1. A salt of a quaternary ammonium compound and an inorganic compound capable of initiating polymerization is formed on an inorganic solid substance, and then polymerization of a monomer having a radical-polymerizable unsaturated bond is initiated. A method for coating an inorganic solid substance with a polymer. 2. The coating according to claim 1, wherein the inorganic compound capable of initiating polymerization is a salt selected from the group consisting of alkali metal or ammonium persulfate, bisulfite and sulfite. Method.