JP4672251B2 - Method for producing aqueous wax dispersion - Google Patents

Description

The present invention relates to a process for preparing an aqueous dispersion of the wax.

  Aqueous wax dispersions are used for various applications in various fields including floor wax, car wax, rust preventive wax, paper product water repellent, thermal transfer ribbon additive, fiber sizing aid, etc. Yes. A conventional aqueous wax dispersion contains an aqueous auxiliary agent for dispersing and stabilizing the wax in an aqueous medium to obtain an emulsified state. Up until now, water-immobilizing aids have been considered necessary for emulsification of wax, but after emulsification, there is a tendency to lower the performance of the wax, such as water resistance, blocking resistance, and antifouling property, in each application. . In addition, since some of the aqueous auxiliaries are pointed out as problems such as environmental hormones, an aqueous wax dispersion not containing the aqueous auxiliaries and a method for producing the same are required.

  Under these circumstances, as a method for dispersing wax without containing an aqueous additive such as an emulsifier, Patent Document 1 describes a method using a high-speed stirrer (homomixer) and a high-pressure homogenizer (homogenizer) as essential devices. ing.

JP 2003-147088 A

However, the above method requires special and expensive apparatuses such as a high-speed stirrer (homomixer) and a high-pressure homogenizer (homogenizer), and a high-pressure treatment of 300 kg / cm ² or more is required to disperse the wax to the nano-order. This is industrially disadvantageous because it must be carried out, and the average particle size of the wax dispersed at a high pressure of 600 kg / cm ² is only dispersed to 0.6 μm or more, and the particle size is not sufficiently small. There were also problems such as insufficient stability and blending stability with other dispersions.

The present invention solves the above problems, and does not use a high-boiling water-forming auxiliary and does not use a special apparatus such as a high-pressure disperser, and the aqueous wax is finely dispersed to an average particle size of 0.5 μm or less. It aims at providing the manufacturing method of a dispersion.

  As a result of intensive studies in order to solve the above problems, the present inventors have found that a wax having a specific saponification value, a basic compound having a boiling point of 300 ° C. or less, and water in a sealed container at 50 to 200 ° C. The aqueous wax dispersion obtained from the step of heating and stirring at temperature found that the wax was homogeneously and finely dispersed and excellent in dispersion stability, and based on them, the present invention was reached.

That is, the first of the present invention is
From a step of stirring a wax having a saponification value of 5 to 250 (mgKOH / g), a basic compound having a boiling point of 300 ° C. or less, and water in a sealed container, and then heating and stirring at a temperature of 50 to 200 ° C. The aqueous wax dispersion is characterized in that the addition amount of the basic compound is 1.5 to 6.5 times equivalent to the amount required for complete saponification of the wax, and the stirring speed is less than 1,000 rpm. It is a manufacturing method .

  According to the present invention, a water-based auxiliary having a boiling point exceeding 300 ° C. is substantially obtained by heating and stirring a wax, a basic compound having a boiling point of 300 ° C. or less, and water in a sealed container at a temperature of 50 to 200 ° C. A wax aqueous dispersion excellent in dispersion stability having a number average particle size of 0.5 μm or less in an aqueous dispersion of wax that is not contained in water can be produced economically and resource-saving, and is moisture-proof. And various applications that require water repellency, such as film moisture-proofing agent, water-repellent agent for paper products, rust-proofing wax, additive for thermal transfer ribbon, fiber sizing aid, floor wax, car wax, etc. It can be suitably used as a coating agent for materials.

  Hereinafter, the present invention will be described in detail.

  The aqueous wax dispersion of the present invention contains a wax having a specific saponification value and a basic compound having a boiling point of 300 ° C. or lower in an aqueous medium.

  The wax used in the present invention needs to have a saponification value of 5 to 250. The saponification value is preferably from 30 to 250, particularly preferably from 50 to 250. If the saponification value is less than 5, it becomes difficult to disperse the wax in water. In addition, it is difficult to obtain a wax having a saponification value exceeding 250, and it is not economical because a special operation is required to obtain this value.

  Examples of the wax having a saponification value of 5 to 250 include animal and plant waxes. Specifically, plant waxes such as candelilla wax, carnauba wax, rice wax, wood wax, jojoba oil, beeswax, and shellac. Animal waxes such as wax, lanolin wax and whale wax are listed. Among them, among plant waxes, candelilla wax, carnauba wax, wood wax, and animal waxes are preferable because beeswax has an appropriate saponification value, and among these, candelilla wax is most preferable. Although the acid value of the wax used for this invention is not specifically limited, Preferably it is 5-50, More preferably, it is 8-40, Most preferably, it is 9-30. In the present invention, the saponification value and the acid value are values determined by titration with KOH according to JIS K-0070, and the unit is mgKOH / g.

  In the aqueous dispersion of the present invention, the above wax is dispersed or dissolved in an aqueous medium. Here, the aqueous medium is a liquid containing water as a main component, and may contain a water-soluble organic solvent or a basic compound described later.

  The number average particle diameter of the wax particles dispersed in the aqueous dispersion of the present invention is 0.5 μm or less. Further, from the viewpoint of stability, 0.3 μm or less is more preferable, and 0.2 μm or less is more preferable. When the number average particle diameter exceeds 0.5 μm, the storage stability of the aqueous dispersion is lowered or the blending stability is lowered. The number average particle diameter of the wax particles is not particularly limited, but is 0.01 μm or more in the case of an aqueous dispersion obtained by the production method of the present invention. On the other hand, the weight average particle diameter of the wax particles is preferably 1 μm or less, more preferably 0.5 μm or less, and particularly preferably 0.3 μm or less from the viewpoint of storage stability and mixing stability.

  In the aqueous dispersion of the present invention, the wax content can be appropriately selected depending on the target performance, mixing conditions with other components, and the like, and is not particularly limited, but the viscosity of the coating composition is appropriately maintained, and 1-60 mass% is preferable at the point which expresses favorable coating-film formation ability, 3-55 mass% is more preferable, 5-50 mass% is further more preferable, and 10-45 mass% is especially preferable.

  The aqueous dispersion of the present invention is characterized by substantially not containing an aqueous auxiliary agent having a boiling point exceeding 300 ° C. For this reason, the coating film characteristics, particularly water resistance and moisture resistance are excellent, and these performances hardly change in the long term. The boiling point as used in the field of this invention is all the boiling points in a normal pressure. Further, the hydration aid having no boiling point at normal pressure corresponds to the hydration aid in the present invention having a boiling point exceeding 300 ° C.

  Here, the “aqueous auxiliary” is a drug or compound added for the purpose of promoting aqueous formation or stabilizing the aqueous dispersion in the production of an aqueous dispersion. In addition, “substantially not containing an aqueous auxiliary agent having a boiling point exceeding 300 ° C.” means that such an auxiliary agent is not used at the time of production (when the wax is aqueous), and the resulting dispersion results in this auxiliary agent. Means that it does not contain. Therefore, it is particularly preferable that the content of such an aqueous auxiliary agent is zero, but it may be contained in an amount of about 0.1% by mass or less based on the wax component as long as the effect of the present invention is not impaired. .

  Examples of the aqueous solubilizing aid having a boiling point exceeding 300 ° C. in the present invention include surfactants described later, compounds having a protective colloid action, water-soluble polymers, and the like.

  Examples of surfactants include cationic surfactants, anionic surfactants, nonionic (nonionic) surfactants, amphoteric surfactants, fluorosurfactants, and reactive surfactants. In addition to those used for emulsion polymerization, emulsifiers are also included. For example, anionic surfactants include sulfates of higher alcohols, higher alkyl sulfonic acids and salts thereof, alkyl benzene sulfonic acids and salts thereof, polyoxyethylene alkyl sulfate salts, polyoxyethylene alkyl phenyl ether sulfate salts, vinyl sulfone salts. Nonionic surfactants include polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyethylene glycol fatty acid ester, ethylene oxide propylene oxide block copolymer, polyoxyethylene fatty acid amide, ethylene oxide. -Compounds having a polyoxyethylene structure such as propylene oxide copolymer and sorbitans such as polyoxyethylene sorbitan fatty acid ester It includes conductors, and examples of the amphoteric surfactant, lauryl betaine, lauryl dimethyl amine oxide, and the like. Examples of reactive surfactants include alkylpropenylphenol polyethylene oxide adducts and their sulfate esters, allyl alkylphenol polyethylene oxide adducts and their sulfate esters, allyl dialkylphenol polyethylene oxide adducts and their sulfate esters, etc. Examples thereof include compounds having a reactive double bond.

  Compounds having protective colloid action, water-soluble polymers include polyvinyl alcohol, carboxyl group-modified polyvinyl alcohol, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, modified starch, polyvinyl pyrrolidone, polyacrylic acid and its salts, acrylic acid-anhydrous Maleic acid copolymer and salt thereof, styrene- (meth) acrylic acid copolymer, ethylene- (meth) acrylic acid copolymer, isobutylene-maleic anhydride alternating copolymer, (meth) acrylic acid- (meth) Carboxyl group-containing polymer having an unsaturated carboxylic acid content of 20% by mass or more such as an acrylic ester copolymer and its salt, polyitaconic acid and its salt, water-soluble acrylic copolymer having amino group, gelatin, gum arabic , Mosquito In such generally compounds which are used as dispersion stabilizer of fine particles.

  The aqueous dispersion of the present invention contains a basic compound having a boiling point of 300 ° C. or lower. This basic compound neutralizes part or all of the carboxyl groups contained in the wax, prevents the aggregation between fine particles due to the electric repulsion between the generated carboxyl anions, and makes the aqueous dispersion stable. Is granted. When a basic compound having a boiling point exceeding 300 ° C. is used, it is difficult to disperse when the aqueous dispersion is applied to a substrate and dried, particularly when drying at a low temperature of about room temperature. The water resistance and moisture resistance of the film may deteriorate.

The basic compound is not particularly limited as long as it has a boiling point of 300 ° C. or lower. Among them, those having a boiling point of 250 ° C. or lower are preferable, more preferably a boiling point of 30 to 200 ° C., particularly preferably 30 to 185 ° C. Specific examples of the basic compounds include ammonia, triethylamine, N, N-dimethylethanolamine, isopropylamine, aminoethanol, dimethylaminoethanol, diethylaminoethanol, ethylamine, diethylamine, isobutylamine, dipropylamine, and 3-ethoxy. Propylamine, 3-diethylaminopropylamine, sec-butylamine, propylamine, n-butylamine, 2-methoxyethylamine, 3-methoxypropylamine, 2,2-dimethoxyethylamine, monoethanolamine, mole Examples include holin, N-methylmorpholine, N-ethylmorpholine, pyrrole, and pyridine. The addition amount of the basic compound is preferably 0.5 to 6.5 times the amount necessary for complete saponification of the wax, more preferably 1.5 to 6.5 times the equivalent, and 2.0 to 6 A 5-fold equivalent is particularly preferred. If it is less than 0.5 times equivalent, the addition effect of a basic compound is not recognized, and even if it adds more than 6.5 times equivalent, it is uneconomical and it is not preferable. The amount of the basic compound necessary for complete saponification of the wax was calculated according to the following formula.
Necessary amount of basic compound = wax amount × saponification value × basic compound molecular weight / KOH molecular weight / 1000
(However, the unit of the wax amount is [g], and the unit of the saponification value is [mg KOH / g].)

  In the present invention, an organic solvent may be added to the aqueous wax dispersion in order to promote blending stability with other dispersions. 50 mass% or less in an aqueous medium is preferable, as for the amount of organic solvents, it is more preferable that it is 0-40 mass%, 0-20 mass% is further more preferable, and 0-10 mass% is especially preferable. When the amount of the organic solvent exceeds 50% by mass, the stability of the aqueous dispersion may be lowered depending on the organic solvent used.

  As the organic solvent, those having a solubility in water at 20 ° C. of 10 g / L or more are preferably used, more preferably 20 g / L or more, and particularly preferably 50 g / L or more from the viewpoint of obtaining a good aqueous dispersion. It is.

  As the organic solvent, those having a boiling point of 300 ° C. or less are preferable from the viewpoint of easy removal from the coating film, more preferably 30 to 250 ° C., more preferably 30 to 200 ° C., and particularly preferably 30 to 185 boiling point. The one having a boiling point of 50 to 185 ° C. is most preferable. An organic solvent having a boiling point exceeding 300 ° C. is difficult to be scattered from the resin coating film by drying, and in particular, the water resistance of the coating film at the time of low-temperature drying and adhesion to the substrate may be deteriorated. Specific examples of the organic solvent to be used include alcohols such as methanol, ethanol and isopropanol, ketones such as methyl ethyl ketone, ethers such as tetrahydrofuran and dioxane, and the like. These organic solvents may be used in combination of two or more.

  Among the above organic solvents, ethanol, isopropanol, methyl ethyl ketone, and tetrahydrofuran are preferable, and ethanol is particularly preferable among them because it is difficult to inhibit the wax from becoming aqueous and has a high effect on stabilizing the formulation.

Next, a method for producing an aqueous wax dispersion will be described.
As the method for obtaining the aqueous wax dispersion of the present invention, the above-described components, that is, wax, basic compound, aqueous medium, and organic solvent as necessary are heated and stirred in a sealable container. A method can be employed, and this method is most preferred. According to this method, it is not necessary to add an aqueous auxiliary agent having a boiling point of 300 ° C. or higher.

  As the container, an apparatus widely known to those skilled in the art as a solid / liquid stirring apparatus or an emulsifier can be used, and an apparatus capable of pressurization of 0.1 MPa or more is preferably used. The stirring method and the rotation speed of the stirring are not particularly limited, but may be stirring at a low speed such that the resin is in a floating state in the aqueous medium. Therefore, high-speed stirring (for example, 1,000 rpm or more) is not essential, and an aqueous dispersion can be produced with a simple apparatus.

  Raw materials such as wax and an aqueous medium are put into the above apparatus, and then the temperature in the tank is kept at 40 to 200 ° C., preferably 80 to 150 ° C., preferably until coarse particles disappear (for example, 5 The aqueous dispersion can be obtained by making the wax sufficiently aqueous by continuing stirring (˜120 minutes) and then cooling preferably to 40 ° C. or lower, preferably with stirring. When the temperature in the tank is lower than 60 ° C., it becomes difficult to make the wax aqueous. A reaction in which the temperature in the tank exceeds 200 ° C. is not preferable because it is uneconomical.

  Examples of a method for adjusting the solid content concentration of the aqueous dispersion thus obtained include a method in which the aqueous medium is distilled off or diluted with water so as to obtain a desired solid content concentration.

  By employing the above production method, the aqueous dispersion of the present invention is obtained by dispersing or dissolving the wax in an aqueous medium and preparing a uniform liquid.

  Since the wax composition obtained from the aqueous dispersion of the present invention is excellent in moisture resistance and water repellency, it is suitable for film moisture resistance, water repellency for paper products, rust wax, additive for thermal transfer ribbon, fiber sizing aid It is suitable as a coating agent for various substrates such as floor wax and car wax.

  In particular, the aqueous dispersion of the present invention has excellent mixing stability with an aqueous dispersion of resin. Examples of such aqueous dispersions of water-dispersible polymers include polyester resins, polyolefin resins, and polyvinyl acetate. , Ethylene-vinyl acetate copolymer, polyvinyl chloride, polyvinylidene chloride, ethylene- (meth) acrylic acid copolymer, styrene-maleic acid resin, styrene-butadiene resin, butadiene resin, acrylonitrile-butadiene resin, poly (meta ) Acrylonitrile resin, (meth) acrylamide resin, chlorinated polyethylene resin, chlorinated polypropylene resin, modified nylon resin, urethane resin, phenol resin, silicone resin, epoxy resin, and other aqueous dispersions. You may mix and use the above.

  If necessary, the aqueous dispersion of the present invention may contain pigments, pigment dispersants, wetting agents, antifoaming agents, thickeners, freeze / thaw stabilizers, coating film forming aids, antiseptics, antifungal agents, and antirusts. It is also possible to add various agents such as an agent, a plasticizer, an antioxidant, an ultraviolet absorber, a radical scavenger, a weathering agent, a flame retardant, a leveling agent, and an anti-waxing agent.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples. Various physical properties were measured or evaluated by the following methods.
(1) Particle diameter (μm) of wax particles: The number average particle diameter (mn) was determined using a Microtrac particle size distribution analyzer UPA150 (manufactured by Nikkiso Co., Ltd., MODEL No. 9340).
(2) Pot life: The appearance when the prepared aqueous wax dispersion was allowed to stand at room temperature for 90 days was evaluated in the following two stages.
○: Solidification and aggregation were not observed ×: Solidification and aggregation were observed (3) Dilution stability: When the prepared aqueous wax dispersion was diluted with pure water so that the wax component was 1% by mass The appearance was evaluated in the following two stages.
○: Solidification and aggregation were not observed. ×: Solidification and aggregation were observed. (4) Blending stability with the aqueous resin dispersion: The prepared aqueous wax dispersion was prepared from an acrylic resin aqueous dispersion (NeoRez R-972). , Enomoto Kasei Co., Ltd., solid content concentration: 42.0% by mass) diluted with water twice, and the appearance when blended so that the solid content becomes 1: 1 is evaluated in the following two stages did.
○: Solidification and aggregation were not observed ×: Solidification and aggregation were observed

Example 1
40.0 g of candelilla wax (hereinafter abbreviated as “CAW”; saponification value: 55.4, acid value: 15.8) using a stirrer equipped with a heat-resistant 1 L glass container with a heater. 5.2 g (1.5 times equivalent of the amount required for complete saponification of wax) of morpholine (manufactured by Nacalai Tesque, boiling point 129 ° C.) and 154.8 g of distilled water were charged in a glass container, and the stirring blade was rotated. When stirring at a speed of 400 rpm, no resin precipitation was observed at the bottom of the container, confirming that it was in a floating state. Therefore, while maintaining this state, the heater was turned on and heated. Then, the system temperature was kept at 100 ° C. and further stirred for 10 minutes. Then, after cooling to room temperature (about 25 ° C.) while stirring with air rotation at 400 rpm, pressure filtration (air pressure 0.2 MPa) with a 300 mesh stainless steel filter (wire diameter 0.035 mm, plain weave) As a result, a pale yellow uniform wax aqueous dispersion J-1 was obtained. There was almost no residual wax on the filter. Various properties of the wax dispersion are shown in Table 1.

Examples 2 and 3
Instead of morpholine, N, N-dimethylethanolamine (manufactured by Wako Pure Chemical Industries, boiling point 134 ° C., hereinafter referred to as “DMEA”), triethylamine (manufactured by Nacalai Tesque, boiling point 88.8 ° C., hereinafter referred to as “TEA”) Aqueous wax dispersions J-2 (Example 2) and J-3 (Example 3) were prepared in the same manner as in Example 1 except that the above was used, and various physical properties were evaluated. Various properties of the wax dispersion are shown in Table 1.

Example 4
Aqueous wax dispersion J-4 was prepared in the same manner as in Example 1 except that the amount of morpholine added was 13.8 g (4.0 times equivalent), and various physical properties were evaluated. Various properties of the wax dispersion are shown in Table 1.

Example 5
A wax aqueous dispersion J-5 was prepared in the same manner as in Example 1 except that 40.0 g (20.0% by mass) of ethanol (Nacalai Tesque) was added, and various physical properties were evaluated. Various properties of the wax dispersion are shown in Table 1.

Examples 6-9
In Example 1, rice wax (hereinafter abbreviated as “RIW” instead of candelilla wax; saponification number: 80.2, acid value: 11.9), carnauba wax (hereinafter abbreviated as “CRW”) Chemical value: 85.1, acid value: 9.1), beeswax (hereinafter abbreviated as “BEW”; saponification value: 90.6, acid value: 15.2), wood wax (hereinafter abbreviated as “JPW”) Saponification number: 220.5, acid value: 27.6), respectively, so that the amount of the basic compound is 1.5 times equivalent to the saponification value of each wax, and the solid content concentration is 20% by mass. Except for the above, the same operations as in Example 1 were performed to obtain wax dispersions J-6 to J-9.

  The measurement results and the like obtained in Examples 1 to 9 are summarized in Table 1.

Comparative Example 1
An attempt was made to produce an aqueous wax dispersion H-1 (Comparative Example 1) in the same manner as in Example 1 except that the basic compound was not added, but it was not dispersed.

Comparative Examples 2 and 3
Aqueous wax dispersion H- in the same manner as in Example 1 except that paraffin (manufactured by Nacalai Tesque, melting point: 42 to 44 ° C) and paraffin (manufactured by Kishida Chemical Co., melting point: 68 to 70 ° C) were used as the wax. 2 (Comparative Example 2) and H-3 (Comparative Example 3) were tried to be produced but were not dispersed. The saponification value of these paraffins was 0.

  The measurement results and the like obtained in Comparative Examples 1 to 3 are shown in Table 1.

  In Examples 1-9, the thing excellent in the dispersibility, dilution stability, and mixing | blending stability was obtained.

On the other hand, since the comparative example 1 did not mix | blend a basic compound, it was inferior to the dispersibility. In Comparative Examples 2 and 3, the wax was a petroleum wax, and the saponification value range defined in the present invention was out of the downward direction, so that the dispersibility was poor.

Claims (1)

  From the step of stirring a wax having a saponification value of 5 to 250 (mgKOH / g), a basic compound having a boiling point of 300 ° C. or less, and water in a sealed container, and then heating and stirring at a temperature of 50 to 200 ° C. The aqueous wax dispersion is characterized in that the addition amount of the basic compound is 1.5 to 6.5 times equivalent to the amount required for complete saponification of the wax, and the stirring speed is less than 1,000 rpm. Manufacturing method.