JPH0573458B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a method for stabilizing an aqueous dispersion of fine powder, and more specifically, an aqueous dispersion of a fine powder that disperses an insoluble fine powder in an aqueous solution in a short time, provides long-term dispersion stability, and does not produce a hard cake. This invention relates to a stabilization method and its dispersion.

[Conventional technology]

Aqueous dispersions of fine powders are used in various industrial fields. For example, dispersion of pigments in the fields of paints and printing inks is an important basic technology, and surfactants called dispersants are used to improve dispersibility. In addition, in recent years, products in which fine powders such as lubricants, metal powders, abrasives, fillers, extenders, sintering agents, conductive agents, solid fuel powders, agricultural chemical powders, disperse dyes, and fungicides are dispersed in aqueous solutions have been introduced. Development is progressing, and dispersion stabilizers are often used in all cases. (Problems with Conventional Techniques) However, such conventional aqueous dispersions have some problems in terms of dispersion stability and the like. For example, JP-A-59-19530, JP-A-60-75324
Although the dispersants shown in the above can provide short-term dispersion stability, all of them cause reaggregation of fine powder at a relatively early stage. For this reason, fine powder particles settle and separate during long-term storage, and a satisfactory product has not yet been found. Furthermore, with conventional anionic dispersants, a good dispersion can be obtained immediately after the dispersion is prepared, and in some cases an effect such as reducing the viscosity of the system can be observed, but when used for a long time, If left undisturbed, the fine powder particles will settle, creating a hard cake of precipitate that is hard and difficult to redisperse. Generally, the better the dispersibility, the easier it is to form a strong hard cake.

[Problem to be solved by the invention]

An object of the present invention is to provide a method for dispersion stabilization that has good dispersibility and excellent long-term stability.

[Means to solve the problem]

As a result of extensive research, the inventors of the present invention have discovered a dispersion stabilization method that can solve the above problems, and have arrived at the present invention. That is, the present invention uses 3 to 3 nitrogen atoms as a dispersant to stabilize the dispersion of insoluble fine powder in an aqueous system.
Molecular weight 1000-100 obtained by adding alkylene oxide to a polyamine compound having 200 molecules
A method for stabilizing the aqueous dispersion of an insoluble fine powder, which is characterized by blending a polyether compound of 10,000 yen and Ramsan gum as essential components, and a dispersion liquid thereof. (Requirements constituting the means) The polyamine compound which is the starting material of the polyether used in the present invention has a nitrogen atom number of 3 to 3 in the molecule.
Examples include polyethyleneimine, polyethyleneimine derivatives, polyakylenepolyamines, and polyalkylenepolyamine derivatives having 200 polyethyleneimines. Polyethyleneimine derivatives and polyalkylenepolyamine derivatives include all compounds derived from polyethyleneimine and polyalkylenepolyamine, such as alcohols, polyols, phenols, amines, polyamines, thiols, and carboxylic acids. , addition polymers of ethyleneimine using a compound having one or more active hydrogens such as polycarboxylic acids as an initiator, and aldehydes, ketones, and alkyls that are reactive with the active hydrogens of polyethyleneimine and polyalkylene polyamines. Examples include reaction products with compounds having active double bonds such as halides and acrylamide, isocyanates, thiocyanates, epoxy compounds, epihalohydrins, carboxylic acids, acid anhydrides, cyanamides, guanidines, and ureas. It will be done. In addition, polyalkylene polyamines include diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, dipropylenetriamine,
Examples include distillation residues obtained in the manufacturing process of tetrapropylene pentamine or polyethylene polyamine. These starting materials can be used alone or in combination of two or more, and can be easily produced by addition reaction with alkylene oxide by a conventional method. That is, the starting material polyamine compound was heated to 100% under an alkali catalyst.
The desired product is obtained by addition reaction with alkylene oxide at ~180°C and 1~10 atm. Preferably, ethylene oxide is present in the alkylene oxide, and in addition, propylene oxide and butylene oxide are present in an amount of 0 to 40% by weight.
One or two types of alkylene oxide may be added, but if alkylene oxide other than ethylene oxide is contained in an amount of 50% by weight or more of the total alkylene oxide added, the aggregation effect will be strong and dispersion stability will be impaired, which is not preferable. The number of moles of ethylene oxide added is 2 to 1 per active hydrogen of the polyamine compound.
150 mol is preferred. Further, alkylene oxide can be used either by block addition or random addition, but it is more preferable to add ethylene oxide to the end by block addition. The average molecular weight of the polyether is 10,000 to 1,000,000, more preferably 5,000 to 800,000. If the average molecular weight is less than 1000, dispersibility will be impaired. Furthermore, polyether derivatives obtained by esterifying some or all of the terminal hydroxyl groups of the polyether compounds are also effective. In this case, the esterified product, which is a polyether derivative, is a dicarboxylic acid such as adipic acid, phthalic acid, maleic acid, or succinic acid, or a reaction product with these acid anhydrides or polycarboxylic acids, and
Examples include sulfuric acid esters and phosphoric acid esters obtained by esterifying polyether by a commonly known method using sulfuric acid, monochlorosulfonic acid, sulfuric anhydride, phosphoric anhydride, and the like. This esterified product may be a hydroxide such as sodium hydroxide, potassium hydroxide, calcium hydroxide, or ammonium hydroxide, or a neutralized product with an amine such as alkanolamine, polyethylene polyamine, or alkylamine. Furthermore, the rhamsan gum used in the present invention has six or more consecutive skeletons represented by the following formula (1) in the molecule, and among them, two glucose, one glucuronic acid, and one rhamnose skeleton in the main chain. It is a compound with a molecular weight of 10,000 to 6,000,000 that has two glucose units in its side chain. Ramzan gum can be easily produced by fermentation of glucose using the producing microorganism Alcaligenes ATCC31961.

[Chemical formula] (M ⁺ is sodium, calcium, potassium, etc.) In the dispersion stabilization method of the present invention, the amount of the polyether compound is 0.01 to
It is used in a proportion of 5.0% by weight, preferably 0.1-2.0% by weight. Further, the aforementioned Ramsan gum is used in an amount of 0.01 to 1.0% by weight, preferably 0.05 to 0.5% by weight, based on the entire dispersion. If the amount of the polyether compound and Ramzan gum used is less than this, the effect will be small, and if it is too large, the improvement in the effect will not be significant and it will be economically disadvantageous. The dispersion stabilization method of the present invention is effective for both inorganic and organic fine powders. Examples of inorganic fine powders include, but are not limited to, kaolin, aluminum silicate, clay, talc, mica, asbestos, etc. Powder, calcium silicate, sericite, bentonite, ultramarine, silicates such as magnesium silicate, calcium carbonate,
Carbonates such as magnesium carbonate, barium carbonate, dolomite, sulfates such as calcium sulfate, barium sulfate, aluminum sulfate, zirconia, magnesia, alumina, antimony trioxide, titanium oxide,
White carbon, diatomaceous earth, metal oxides such as iron oxide, zinc oxide, hydroxides such as aluminum hydroxide, iron hydroxide, etc., ultramarine, silicon carbide,
Silicon nitride, boron nitride, barium titanate, carbon black, graphite, molybdenum disulfide, carbon fluoride, sintered ceramic powder, carbon fiber powder, sulfur powder, magnetic powder, iron powder, aluminum powder, copper powder, nickel powder, Gold powder, silver powder, etc., and organic fine powders such as insoluble azo pigments, azo disperse dyes,
Colorant powders such as anthraquinone disperse dyes, threne dyes, phthalocyanine pigments, lake pigments, perylene pigments, dioxazine pigments, quinacridone pigments, polyethylene resins, polystyrene resins, urethane resins, polyamide resins, acrylonitrile resins, Teflon resins, melamine isocyanurate Examples include resin powders such as resins and Bakelite resins, and fine powders of solid paraffin, coal, agricultural chemicals, fungicides, antioxidants, ultraviolet absorbers, flame retardants, and the like. The average particle diameter of these fine powders is preferably 100 microns or less, generally about 0.01 to 50 microns. In addition, the concentration of fine powder in the dispersion system may be any concentration as long as a dispersion system can be obtained.
Generally, it is often used at 10 to 80% by weight. In water as a dispersion medium in which the above-mentioned solid fine powder is dispersed, a water-soluble inorganic salt, urea or methanol, ethanol, butyl cellosolve, and one type of ethylene glycol, propylene glycol, sorbitol, glycerin, polyethylene glycol, polyethylene-polypropylene glycol, etc. are added as an antifreeze agent. Alternatively, two or more types can be used by mixing and dissolving up to 20% by weight in water. In the dispersion stabilization method of the present invention, any disperser may be used, such as a ball mill, sand mill, visco mill, three-roll mill, attritor, etc., for mixing. In addition, the polyether compound and Ramsan gum added as agents are added before or after the process of pulverizing the secondary particles with the dispersion machine, but generally, adding them before the process improves the dispersion and pulverizes the secondary particles. This is preferable because it will be faster. Furthermore, a preservative (organic amine type, organic sulfur type, organic halogen type, benzoic acid ester type) or antifoaming agent (silicon type, polyglycol type) etc. may be used in combination with the aqueous dispersion of the fine powder of the present invention. can.

[Effect]

The method of aqueous dispersion stabilization of fine powder of the present invention makes it possible to form an unprecedented slurry of a wide variety of fine powder substances with a wide range of dispersoid concentrations into a slurry with good handling properties, which is stable for a long time and does not separate. The reason why the dispersibility and stability effects can be obtained is that the polyether compound, which is an essential component, has a special molecular structure with high molecular weight and bulk, and a polyethylene glycol chain with strong hydrophilicity. It has a special molecular structure with two glycol chains in its side chains.
Since it is composed of highly hydrophilic and high molecular weight saccharides, the above two drugs are strongly adsorbed to the fine powder particles in water in a well-balanced manner, effectively, and have a protective colloid effect on the fine powder particles. This is thought to be due to the fact that the dispersibility is large, a synergistic effect of dispersibility appears, and the force (action) of dispersing the primary particles and preventing reagglomeration acts more strongly.

【Example】

EXAMPLES The present invention will be specifically explained below with reference to examples, but the present invention is not limited thereto in any way. Table 1 shows the polyether compounds or derivatives of polyether compounds used here. Furthermore, the dispersion stability performance was evaluated by the following test.
The test results are shown in Tables 2 and 3. <Dispersion Stability Test> A predetermined amount of insoluble fine powder is added to an aqueous solution containing a predetermined amount of additives shown in Table 2 so that the solid content is 20 to 50% by weight to give a total weight of 1 kg. This mixture was pulverized and mixed in a bead mill for 30 minutes to obtain a dispersion. Next, put this dispersion liquid into a 500ml graduated cylinder, seal it tightly, and leave it in a constant temperature room at 30℃.The dispersion state after 3 days and 60 days (evaluation -1), and the precipitate that occurred after 200 days. Hardness and ease of redispersibility (evaluation -2) were evaluated. (Evaluation-1) The dispersion state is evaluated using the symbols in the following items to determine whether or not the fine particles are dispersed without settling. ◎: All the powder is dispersed in the liquid, and no precipitation occurs at the bottom. ○: Most of the powder is dispersed in the liquid, but a slight amount of precipitation occurs at the bottom. △: Approximately half of the powder settles at the bottom. ×: Most of the powder is precipitated at the bottom. (Evaluation-2) The hardness of the precipitate and the ease of redispersibility are evaluated using the following symbols. ◎: There is almost no precipitate, and redispersion is easy. ○: The precipitate is soft and can be easily redispersed by stirring the dispersion liquid. △: Because the precipitate is hard, it will not be redispersed unless strongly stirred with a glass rod. ×: The precipitate was very hard and could not be redispersed.

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【Effect of the invention】

The present invention is a method of making an aqueous slurry from different types of fine powders, and is an ideal product that speeds up the dispersion of fine powders during slurry production, improves workability, and has excellent long-term stability. By providing the method for producing a dispersion liquid and the dispersion liquid, the present invention can widely contribute to the advancement of technology for dispersion stability in aqueous fine powder dispersion.

Claims (1)

[Claims] 1. A polyether compound with a molecular weight of 1,000 to 1,000,000 obtained by adding an alkylene oxide to a polyamine compound having 3 to 200 nitrogen atoms as a dispersant for stabilizing the dispersion of insoluble fine powder in an aqueous system. A method for stabilizing an aqueous dispersion of an insoluble fine powder, which comprises blending and Ramzan gum as essential ingredients. 2. The method for stabilizing the aqueous dispersion of insoluble fine powder according to claim 1, wherein the polyether compound has a structure having ethylene oxide at the end. 3. An aqueous dispersion of insoluble fine powder obtained according to claim 1 or 2.