JPH02298331A - Dispersing agent for inorganic powder - Google Patents

Abstract

PURPOSE:To improve dispersibility for inorg. powder by preparing a dispersing agent by treating the copolymer of a, most 10 C fatty acid vinyl, 4-40C alpha-olefin and maleic anhydride with a basic substance. CONSTITUTION:A copolymer is produced by the radial solution polymerization of at most 10 C fatty acid vinyl (component A), 4-40 C alpha-olefin (component B) and maleic anhydride (component C) which is performed in the presence of a solvent such as methyl acetate using a radical polymerization initiator. This copolymer is treated with a basic substance under conditions as not to allow the component A to be converted into vinyl alcohol unit in the presence of water so as to obtain a polymer electrolyte. A dispersing agent is then prepd for use in inorg. powder with this polymer electrolyte as an effective component. As the inorg. powder, calcium carbonate is effective.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Industrial Field of Application The present invention relates to dispersants for inorganic powders, in particular calcium carbonate and/or clay powders.

The aqueous dispersion obtained by dispersing inorganic powder in an aqueous medium using the dispersant of the present invention has good dispersibility and is excellent in equipment stability and stability against heat and large shear forces. It has good stability even when used in combination with various binders such as polyvinyl alcohol and polyvinyl alcohol. Therefore, the dispersant of the present invention is useful in various industrial fields such as paints and coatings.

B. Prior Art Conventionally, various dispersants have been used to obtain aqueous dispersions of inorganic powders. Dispersants used for this purpose include, for example, anionic surfactants such as higher fatty acid soaps and alkyl sulfates; cationic surfactants such as quaternary ammonium salts; and (1) ethylene glycol alkyl ethers.

Examples include 7-ionic surfactants such as polyethylene glycol fatty acid ester; polyvinyl alcohol; polyacrylates; styrene-maleic anhydride copolymers: formalin condensates with naphthalene sulfonic acid groups. These dispersants are in practical use in various industrial fields. On the other hand, as dispersants that can be used to obtain an aqueous dispersion of coal powder, naphthalene sulfonic acid group formalin condensates, lignin sulfonate salts, etc. , polyoxyenalene alkylphenyl ether, HoIJ acrylate, polyoxyethylene alkyl ether sulfurized salt, salt of copolymer of acrylic acid and vinyl monomer, etc. are known.

Problems to be solved by the C2 invention In recent years, from the perspective of energy conservation, there has been a movement to increase the concentration of aqueous dispersions made by dispersing inorganic powders in an aqueous medium in order to save labor in the subsequent drying process. There is a growing trend to reduce the amount of dispersants added in order to reduce costs and prevent deterioration in the performance of coating films due to dispersants. is also becoming more severe. Under these circumstances, it cannot be said that the above-mentioned dispersants that are used in practice for obtaining aqueous dispersions of inorganic powders necessarily have satisfactory performance.

Furthermore, even if a substance known as a dispersant for coal powder is used as a dispersant for inorganic powder, the same good performance as that for coal powder is usually achieved for inorganic powder. Dispersion performance cannot be reproduced. This is 1 for inorganic powder and coal powder.
This is presumed to be due to different dispersion mechanisms, such as differences in the wettability of the dispersion and adsorption of the dispersant to the dispersion.

Therefore, one object of the present invention is to have excellent dispersion performance for a wide range of inorganic powders, especially calcium carbonate powder and/or clay powder, and to increase the concentration and lower the viscosity of aqueous dispersions. Another object of the present invention is to provide a dispersant that can improve storage stability, improve stability against heat and large shearing forces, and improve stability when used in combination with a binder.

01Means to solve problems According to the invention, the above objectives are achieved.

(A) Fatty acid vinyl having 10 or less carbon atoms.

(B) A copolymer obtained by copolymerizing an α-olefin having 4 to 40 carbon atoms and 0 maleic anhydride, the copolymer comprising a fatty acid vinyl having 10 or less carbon atoms as the component (A) and the component (B). The molar ratio of α-olefins having 4 to 40 carbon atoms is 99.5 to 0.5 to 90 to 1O, and the mole content of fatty acid vinyl as a quaternary component and the α-olefin as a component (B). A polymer electrolyte obtained by treating a copolymer whose sum of numbers is 0.8 to 1.2 times the number of moles contained in maleic anhydride, which is the q component, with a basic substance is used as an active ingredient. This is achieved by providing an aqueous dispersant for inorganic powder, which is characterized by containing:

A specific example of the fatty acid vinyl having 10 or less carbon atoms, which is component (A) used in the present invention, is vinyl acetate.

Examples include vinyl propionate, vinyl butyrate, and vinyl caprylate, among which vinyl acetate is preferably used.

The α-olefin having 4 to 40 carbon atoms as the component (H) used in the present invention includes 1-hexene, 1-octene, 1-dobutane, 1-hexadecene, 1-eicosene,
Examples include linear α-olefins such as 1-triacontin; and branched α-olefins such as 9,9-dimethyl-1-decene. In the invention, the α-olefin used as component (B) must have 4 to 4θ carbon atoms.

It is preferable that it is 6-30. When the number of carbon atoms is less than 4, the dispersing performance of the resulting dispersant is low.

This is presumed to be because the corresponding alkyl side chain contained in the polymer electrolyte has insufficient hydrophobicity and the adsorption of the polymer electrolyte to the inorganic particles is low. Conversely, when the number of carbon atoms is greater than 40, the dispersing performance of the resulting dispersant is also low. this is.

It is presumed that this is because the association of the corresponding alkyl side chains contained in the polymer electrolyte is large, and as a result, the adsorption power of the polymer electrolyte to the inorganic particles is low.

In the copolymer obtained by copolymerizing the above four components, component (B) and component (C) according to the present invention, the molar ratio of component (A) and component (B) is 99.5 to 0.5 to 90. vs 1
0, preferably 99:1 to 95:5.

The number of moles contained in component (B) is 99.
If it is less than 0.5 relative to 5, the dispersing performance of the obtained dispersant is low. This is due to insufficient hydrophobicity derived from the corresponding alkyl side chain contained in the polymer electrolyte.
This is presumed to be due to the low adsorption of the polymer electrolyte to inorganic particles. Further, when the number of moles of component (B) contained is greater than 10 compared to 90 of the number of moles contained in the four components, the dispersing performance of the obtained dispersant is low. This is due to the large association between the corresponding alkyl side chains contained in the polymer electrolyte.

This is presumed to be because the adsorption power of the polymer electrolyte to the inorganic particles is low as a result.

The sum of the number of moles contained in the (N component and out) component in the copolymer according to the present invention is 0.8 to 1.2 times, preferably 1 time, the number of moles contained in component C). . C)
The components maleic anhydride, fatty acid vinyl such as component (A), and α-olefin such as component (B) are known as an alternating copolymerization system, and are not affected much by the ratio of the amounts of each component. %q Acid component (A) component and CB) component and (C) component are mixed alternately at a ratio such that the number of moles contained is approximately 1 times the sum of the number of moles contained in component (A) and (B) component. Easily forms polymers. (The sum of the number of moles contained in the Al component and the (Bl component) is 0 with respect to the number of moles contained in the C) component.
．． When it is less than 8 times -'- or exceeds 1.2 times, the dispersing performance of the obtained dispersant is low.

In addition, (N
The usage f of the component and the component (B) is such that the sum of the number of moles contained in the component (A) and the component (B) is 0.
Since it is easy to obtain a copolymer of 8 to 1.2 times the amount, the copolymerization rate is fast, and the amount of residual unreacted monomer can be reduced, 0.8 to 1.2 to the number of moles of component 0
Preferably, the amount is doubled, and more preferably about 1 times the amount.

The copolymer monomer components forming the bottom of the copolymer that provides the polymer electrolyte used in the present invention are four components, component (B) and
Although only the component may be used, the copolymer may also contain a small amount of other copolymerizable monomer components within a range that does not impede the object of the present invention. The content of such other copolymerizable monomer components is preferably 30 molti or less, more preferably 10 molti or less, and most preferably Vi5 molti or less. Specific examples of such other copolymerizable monomers include acids such as acrylic acid, methacrylic acid, crotonic acid, and itaconic acid.

and esters thereof; (meth)acrylamide and its derivatives; styrene; acrylonitrile; vinylpyrrolidone; vinyl chloride: vinyl fluoride.

There is no particular restriction on the number average molecular weight of the copolymer.

2,000 to 20,000 before reacting with basic substances
is preferred. If the molecular weight of the copolymer is too low, the dispersion stabilizing effect on the inorganic powder will be low, and if it is too high, the copolymer will cause aggregation of the inorganic powder or the viscosity of the aqueous dispersion will increase significantly. There is. There are no particular limitations on the method for controlling the molecular weight of the copolymer, and known methods include method using a chain transfer agent 1, method in which the amount of chain transfer to the solvent is varied by changing the solvent concentration during polymerization.

When considering industrial production, a method using a chain transfer agent is preferred. Chain transfer agents include aldehydes and mercaptans. Examples of the aldehyde include formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, isobutyraldehyde, valeraldehyde, isovaleraldehyde, piparaldehyde, capron-rdehyde, heptaldehyde, and capryaldehyde.

n-octylaldehyde, 2-ethyl-hexylaldehyde% n-capricaldehyde, n-decylaldehyde, n-undecylaldehyde, 9lyl aldehyde,
Examples of the mercaptan include n-tridecylaldehyde, cetylaldehyde, valmitylaldehyde, and stearylaldehyde.

(DJ formula J-8R) mercaptan represented by n (herein, R represents a hydrocarbon group having 1 to 40 carbon atoms which may be substituted with a carboxyl group, and n is 1 or 2); ethylene Thioglycol, propylene thioglycol,
Examples include mercaptans having a hydroxyl group such as butylene thioglycol, where component p) includes methyl mercaptan, n-dodecyl mercaptan, n-hexadecyl mercaptan, n-octadenlumerbutane, n triacontyl mercaptan, 1.10-Dimercabutotecan linear alkyl mercaptans; alkyl mercaptans with branches such as sec-butyl mercaptan and t-dodecyl mercaptan; alicyclic mercaptans such as cyclohexyl mercaptan: phenyl mercaptan, tolyl mercaptan, naphthyl mercaptan Aromatic mercaptans such as; alkyl mercaptans having a carboxyl group such as thioglycolic acid and mercaptopropionic acid:
Examples include aromatic mercaptans having a carboxyl group such as p-mercaptobenzoic acid. Among the above-mentioned chain transfer agents, mercaptan is good in terms of chain transfer efficiency, and among the mercaptans, the above (D> component) is the best.Furthermore, among the (C) component, the dispersion performance of the resulting dispersant is particularly high. From the point of view, mercaptan, which is a hydrocarbon group having 1 to 20 carbon atoms, where R in 2R+S H )n may be substituted with a carboxyl group, appears. In mercaptan, some of the hydrogen atoms bonded to carbon atoms may be substituted with syl groups in the carboxyl group; chlorine, bromine, fluorine, etc., but they are highly reactive with maleic anhydride. It is desirable that they are not substituted with functional groups such as hydroxyl groups or amine groups that exhibit .

Further, the p component may be a single substance or a mixture thereof, as long as it is represented by the chemical formula R(-SH)n.

Copolymerization of four components, (B) component 2 and (C) component, preferably in the presence of a chain transfer agent such as component 0. It is preferable to carry out ordinary solution-based radical polymerization.

Acetate esters such as methyl acetate and ethyl acetate are particularly suitable as solvents because they can perform homogeneous polymerization.
Other solvents, such as aromatic hydrocarbon solvents such as toluene:
Ketone solvents such as acetone and methyl ethyl ketone; ether solvents such as tetrahydrofuran; alcohol solvents such as t-butanol; solvents such as dimethyl sulfoxide; and dimenalformamide can also be used as appropriate.

For copolymerization, it is best to use a common radical initiator. As the radical initiator, azo compounds such as α,α'-azobisisobutyronitrile, hypercrystalline compounds such as benkitasil peroxide, etc. are preferably used.

The obtained copolymer is water-insoluble up to this '1. By treating with a basic substance, the maleic anhydride unit is ring-opened and converted into a water-soluble or water-dispersible polymer electrolyte. The amount of the basic substance to be used is selected within a range that makes the copolymer water-soluble or water-dispersible, but usually the carboxyl group introduced by the maleic anhydride unit and the carboxyl group introduced by tomercabutane are selected. Approximately 0.3 to 1 part is used for the total amount.

As basic substances, alkali metal hydroxides such as hydroxide, potassium hydroxide; calcium hydroxide,
Alkaline earth metal hydroxides such as magnesium hydroxide; ammonia; amines having 6 or less carbon atoms such as triethylamine, etc. are used. Treatment of copolymers with basic substances is common. The process is carried out under conditions such that the four components contained in the copolymer are not converted into vinyl alcohol units in the presence of water. The processing temperature is usually room temperature to 40°C.
A temperature of approximately ℃ is selected.

The dispersant of the present invention includes, for example, cadmium yellow, red red iron, chrome yellow, gunjo, lead white, titanium white,
Inorganic powders such as carbon black, aluminum hydroxide, clay, Merck, alumina, silica, barium titanate, magnesium carbonate, calcium carbonate, quartz powder, calcium silicate; γ-F18202, CO-coated T-Fe2O2
, Meta A/powder, soft ferrite such as Ni-Zn system/Mn-Zn system, magnetic powder such as Cr(h): metal carbide such as silicon carbide, gold IHI compound such as silicon nitride, metal such as titanium boride, etc. It is advantageously used when dispersing powders of inorganic substances such as borides, metal sulfides, and metal phosphides in aqueous media, and among them, calcium carbonate and clay alone or a combination of calcium carbonate and clay are used. A particularly remarkable dispersion performance is exhibited when an inorganic powder of .

There are no particular limitations on the method of using the dispersant of the present invention.

For example, when dispersing powder, it is possible to adopt a method in which the dispersant of the present invention is added and mixed in advance into an aqueous medium, and then inorganic powder is added and mixed. When dispersing after pulverization, a method is adopted in which a dispersant is added to the system Kff5 before, during or after pulverization. The dispersant of the present invention is usually 0.0% relative to the inorganic powder.
5-5.0% by weight.

It is preferably used in a range of about 0.1 to 1.0 weight. The aqueous medium to which the dispersant of the present invention is applied may be water alone, or a water-soluble organic solvent 1 such as alcohol may be mixed with water depending on the purpose. In addition, the dispersant of the present invention includes a polyvinyl alcohol polymer, a cellulose derivative, an oxidized starch, and a styrene-butadiene copolymer.
It is also advantageously used in systems where a binder is present, such as HHE-r-mulsion, and the dispersant of the present invention may also be used in combination with other surfactants, wetting agents, protective colloids, etc.

E Examples The present invention will be explained in more detail with reference to Examples below.1
The present invention is not limited in any way by these Examples. In the following, "parts" and "%" mean "parts by weight" and "% by weight," respectively, unless otherwise specified.

Production Example 1 1077 parts of maleic anhydride and 91 parts of vinyl acetate in a polymerization container
7 parts, 106 parts of an α-olefin mixture having an average carbon number of 23 (manufactured by Mitsubishi Kasei ■) and 1400 m of ethyl acetate were heated to 70°C under a nitrogen atmosphere, and then 40.5 parts of thioglycolic acid and α, α Polymerization was started by adding 7.9 parts of '-azobisisobutyronitrile. α after starting polymerization
, 3.9 parts of α'-azobisisobutyronitrile was added at the 1.5th hour, 5.9 parts at the 3rd hour, and 7.9s were added every hour from the 4th hour until the 8th hour. Added. Polymerization was stopped by cooling at 9 hours. The polymerization rate of vinyl acetate at this time was 98%. After evaporating low-boiling substances such as ethyl acetate and unreacted vinyl acetate from this solution, the remaining solids are ground into powder. When this powder was analyzed by gel permeation chromatography, the number average molecular if'i of the copolymer was approximately 5 in terms of borisnarene.
It was ooo. In addition, 1H-NM regarding the copolymer
As a result of R measurement, the molar ratio of vinyl acetate units and α-olefin units is 97:3, and the sum of the number of moles of vinyl acetate units and α-olefin units is 1 to the number of moles of maleic anhydride units. It turned out to be .0 times 'fc.

To 100 parts of the copolymer powder, 1120 parts of water and 25
% aqueous ammonia was added to dissolve the powder to prepare a 10% aqueous solution of the dispersant. This is 1 of the polymer electrolyte body)
Make it a 0% aqueous solution.

Production Examples 2 to 5 Vinyl acetate (9
17flS), α-olefin maleic anhydride in ethyl acetate in the presence of α, α′-azobisisobuteroni) gel, with or without a chain transfer agent 70
The copolymer powder obtained after the treatment was polymerized at ℃ for 9 hours and dissolved in an aqueous solution of a basic substance.
% aqueous solution was obtained. Note that while checking the progress of polymerization every 1.5 hours from the start of polymerization, α, α′-
An appropriate amount of azobisisobutyronitrile was added. Also,
IH-NMR measurement results for the obtained copolymer,
Ip of the number of moles of vinyl acetate units and α-olefin units in the copolymer is 1.
It turned out to be 0x. Table 1 shows the nine conditions employed in the production of copolymers and the production of polymer electrolytes from the copolymers, and the 1H-NMR of the obtained copolymers.
It was determined by measurement that the vinyl acetate unit and α-
The approximate number average molecular weights (in terms of polystyrene) of the copolymers determined by olefin unit and molar ratio permeation chromatography are shown in Table 2 together with those in Production Example 1.

Below is a margin Table 2 Comparative Production Examples 1 to 5 By the same operation as in Production Example 1, vinyl acetate (9
17 parts), maleic anhydride, and optionally further α
-Olefins α in ethyl acetate.

Polymerization was carried out at 70° C. for 9 hours in the presence of α′-azobisisobutyronitrile and thioglycolic acid, and the copolymer powder obtained after treatment was dissolved in an aqueous solution of a basic substance.
Specializes in 10% aqueous solutions of polymer electrolytes. 1.5 hours after the start of N-polymerization, an appropriate amount of α,α'-azobisisobutyronitrile was added as necessary while checking the progress of polymerization. In addition, 1H- about the obtained copolymer
As a result of NMR measurement, the vinyl acetate unit and α-
It turns out that the sum of the number of moles of olefin units is 1.0 times the number of moles of maleic anhydride units. Table 3 shows the conditions adopted in the production of the copolymer and the production of the polymer electrolyte from the copolymer. Table 4 shows the molar ratio of vinyl units to α-olefin units and the approximate number average molecular weight (in terms of polystyrene) of the copolymer determined by gel permeability chromatography.

Table 4 Examples 1 to 10 and Comparative Examples 1 to 7 The polymer electrolytes (a) obtained in Examples 1 to 5 and Comparative Production Examples 1 to 5 were added to 2 m of inorganic powder. ~(j),
One kind of 10% aqueous solution of a dispersing agent selected from sodium polyacrylate and sodium hexametaphosphate was added, and then water was added and the mixture was heated at 5000 rpm using a homomexer.
By stirring for 10 minutes, you can create a binder-free aqueous dispersion. The viscosity at 20° C. of the aqueous dispersion of such a binder-free system is as follows:
After being left at 20° C. for 1 day and 5 days at 20° C., each sample was measured using a BL type viscometer manufactured by Tokyo Keiki ■. I cut it. The binder-added aqueous dispersion has a polymerization degree of 13 (10
, degree of saponification 985 mol - 10 of polyvinyl alcohol
% aqueous solution, oxidized starch [manufactured by Nihon Shokuhin@, product name rMs
20% aqueous solution of asooJ) and 48% styrene
Butadiene copolymer emulsion [manufactured by Asahi Tau #, trade name rSBR-Em 1622 J] was mixed with polyvinyl alcohol, rRated starch, and styrene-butadiene copolymer emulsion with each inorganic powder.
Binder solutions prepared by mixing amounts of 5%, 8% and 12% were placed in a 500 cc beaker.
While stirring with a propeller at 30 Urp+n, a binder-free aqueous dispersion was gradually added thereto according to the preparation method described above, and stirring was continued for an additional 10 minutes. The viscosity at 20°C of the binder-added aqueous dispersion was measured immediately after preparation.

Table 5 shows the names and amounts of the dispersants used.

Furthermore, Tables 6 and 7 show the inorganic powder and binder used to prepare the aqueous dispersion and the viscosity of the resulting aqueous dispersion.

Table 5 F6 Effects of the Invention According to the present invention, as is clear from the above examples, it has excellent dispersion performance for a wide range of types of inorganic powders, and can increase the concentration of aqueous dispersions. Lower viscosity, improved storage stability, improved stability against heat and large shear forces,
Also provided is a dispersant that enables improved stability when used in combination with a binder.

Claims (4)

[Claims] (1) A copolymer obtained by copolymerizing (A) a fatty acid vinyl having 10 or less carbon atoms, (B) an α-olefin having 4 to 40 carbon atoms, and (C) maleic anhydride, which Ingredients and (B
) The content molar ratio of the components is 99.5:0.5 to 90:10, and the sum of the number of moles contained in the component (A) and the component (B) is relative to the number of moles contained in the component (C). A dispersant for inorganic powder, characterized in that it contains as an active ingredient a polymer electrolyte obtained by treating a copolymer of 0.8 to 1.2 times with a basic substance. (2) The copolymer has the formula (D) R-(SH)_n (where R represents a hydrocarbon group having 1 to 40 carbon atoms which may be substituted with a carboxyl group, and n is 1 or 2. ), component (A), component (B) and (C
2. The dispersant according to claim 1, which is a copolymer obtained by copolymerizing components (). (3) Component (D) is a mercaptan having the formula R-(SH)_n, where R is a hydrocarbon group having 1 to 20 carbon atoms which may be substituted with a carboxyl group, and component (A) is vinyl acetate. Component (B) is an α-olefin having 6 to 30 carbon atoms, the molar ratio of component (A) to component (B) is 99:1 to 95:5, and the number average of the copolymer is The dispersant according to claim 2, which has a molecular weight of 2,000 to 20,000. (4) The dispersant according to claim 1, wherein the inorganic powder is calcium carbonate and/or clay powder.