JP2014151311A - Aqueous suspension composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composition which is formed by stably suspending zinc oxide and/or zinc oxide-based complexes in water without raising agglomeration, precipitation and the like.SOLUTION: Using a method comprising: mixing at least one suspensoid component (a) selected from a group consisting of zinc oxide and zinc oxide-based organic complexes and water; wet-crushing the obtained mixture; and adding to the wet crushed product at least one component (b) selected from a group consisting of citric acid and salts thereof, the composition is obtained which contains: at least the one suspensoid component (a) of 1 mass% or more, selected from the group consisting of zinc oxide and zinc oxide-based organic complexes; at least the one component (b) selected from the group consisting of citric acid and salts thereof; and water, and which may contain a surfactant of 10 mass% or less. In the composition, a content of the component (b) is 0.1 to 100 mass parts relative to 100 mass parts of the suspensoid (a), pH is 6.5 or higher, and the suspensoid does not include inorganic compounds other than the component (a).

Description

  The present invention relates to an aqueous suspension composition. More specifically, the present invention relates to a composition in which zinc oxide and / or a zinc oxide-based organic complex widely used in the industrial field is stably suspended in water without causing aggregation or precipitation.

  Compositions obtained by suspending zinc oxide in water are widely used as cosmetics, ultraviolet shielding materials for photographic materials, pharmaceuticals, antibacterial agents, pigments, fillers, ceramics, or raw materials for various zinc compounds.

  Also known is a composition obtained by suspending in water a composite or combination of zinc oxide and another compound. For example, Patent Document 1 discloses composite particles in which zinc pyrithione is coated on core particles made of zinc oxide. Cited references 2 to 4 describe various complexes composed of a pyrithione compound and zinc oxide. Patent Document 5 describes a complex of an isothiazolone compound and zinc oxide. Furthermore, a complex of ferritin and zinc oxide is described in Patent Document 11.

  In a composition obtained by suspending zinc oxide in water, precipitation, solidification, and the like are likely to occur due to aggregation of zinc oxide particles, and operations such as redispersion and pulverization by stirring become difficult. It has long been desired to improve the disadvantages of such zinc oxide fine particle suspensions.

  As a method for stabilizing the zinc oxide fine particle suspension, a method using a relatively large amount of a specific surfactant has been mainly employed (see Patent Documents 6 and 7). Patent Document 8 describes an aqueous dispersion containing zinc oxide as a pigment, water-swellable smectite, and a dispersant. Here, when a carboxylic acid type dispersant and an organic acid such as citric acid or a salt thereof are used in combination as a dispersant, it seems that dispersibility and fluidity are improved. Patent Document 9 describes an aqueous dispersion containing zinc oxide and citric acid as a raw material for producing zinc salt particles used as a developer. Patent Document 10 discloses a deodorant dispersion containing a deodorant component comprising a zinc compound such as zinc oxide, an aliphatic polycarboxylic acid or a salt thereof, and hydrous silicic acid. This describes citric acid as an aliphatic polycarboxylic acid.

JP-T-2002-521339 WO2005 / 040122 JP 2006-335757 A WO2009 / 144929 JP 2007-332111 A JP-A-9-235156 JP 2010-30836 A JP 2001-271007 A JP-A-6-135132 Japanese Patent Laid-Open No. 10-305086 JP 2009-190982 A

  An object of the present invention is to provide a composition in which zinc oxide and / or a zinc oxide-based organic complex widely used in the industrial field is stably suspended in water without causing aggregation or precipitation.

  As a result of diligent studies to solve the above-mentioned problems, zinc oxide as a suspension is mixed with water as a suspension medium, and citric acid or a salt of citric acid is added thereto to agglomerate zinc oxide. It has been found that an aqueous suspension composition can be obtained that is inhibited and has significantly improved suspension stability. As a result of further investigations based on this finding, the present inventors have completed the present invention.

That is, the present invention includes the following aspects.
[1] At least one suspension component (a) selected from the group consisting of zinc oxide and a zinc oxide-based organic complex (a) 1% by mass or more, and at least one component selected from the group consisting of citric acid and its salt ( b) and water,
A surfactant can be contained in an amount of 10% by mass or less,
The amount of the component (b) is 0.1 to 100 parts by mass with respect to 100 parts by mass of the suspended solid component (a),
A composition having a pH of 6.5 or more and containing no inorganic compound other than component (a) as a suspension.

[2] The composition according to [1], wherein the suspended solid component (a) is a zinc oxide-based organic complex composed of zinc pyrithione and zinc oxide.
[3] The composition according to [1], wherein the suspension component (a) is zinc oxide and the surfactant content is 0% by mass.

[4] Mixing at least one suspension component (a) selected from the group consisting of zinc oxide and a zinc oxide-based organic complex with water.
The resulting mixture is wet crushed,
The method for producing a composition according to any one of [1] to [3], comprising adding to the wet pulverized product at least one component (b) selected from the group consisting of citric acid and a salt thereof. .

  In the aqueous suspension composition of the present invention, aggregation of zinc oxide particles is suppressed, suspension stability is extremely good, and sedimentation, solidification, and the like hardly occur. By stirring the aqueous suspension composition of the present invention even after being left for a long time, the zinc oxide particles can be easily resuspended and excellent in handleability.

  The aqueous suspension composition of the present invention (hereinafter sometimes referred to as “the composition of the present invention”) is at least one suspension component (a) selected from the group consisting of zinc oxide and a zinc oxide-based organic complex. 1% by mass or more, at least one component (b) selected from the group consisting of citric acid and its salts, water, and optionally a surfactant, and the suspension component (a) is water It is suspended in the water.

  The suspension component (a) used in the present invention is at least one selected from the group consisting of zinc oxide and zinc oxide-based organic composites.

  Zinc oxide is used for white pigments (paint materials), cosmetics, pharmaceuticals, electronic components (varistors, ore detectors), semiconductors, transparent electrodes, photocatalysts, lightning arresters, light offset printing, photoreceptors, antibacterial agents, etc. Conventionally known.

  The zinc oxide organic complex used in the present invention is a complex composed of zinc oxide and an organic compound. Examples of the zinc oxide-based organic complex include a complex in which zinc pyrithione is coated on a core particle made of zinc oxide as described in Patent Document 1, and ferritin as described in Patent Document 11. A complex composed of a protein having a cavity such as the above and a zinc oxide filled in the cavity, a complex composed of zinc pyrithione and zinc oxide as described in Patent Document 2, etc., copper pyrithione and zinc oxide And the like. Zinc oxide and zinc oxide-based organic composites can be used alone or in combination of two or more. The composite has the same elemental composition as the combined elemental composition of the raw material, but has a molecular structure different from that of the raw material, and maintains the structure of the raw material However, in the present invention, those having a molecular structure different from each structure of the raw material are preferably used. For example, as described in Patent Documents 2 to 4, a complex composed of zinc oxide and zinc pyrithione gives different results from the raw material zinc oxide and zinc pyrithione in X-ray diffraction and thermal analysis, Light irradiation or coloring by iron ions is less than that of the raw material zinc pyrithione.

  The size of the component (a) suspended in water in the composition of the present invention is preferably 0.1 to 20 μm, more preferably 0.5 to 5 μm. The size of the suspended solid component (a) is a value calculated as an average particle size in a volume-based particle size distribution by measuring with a laser diffraction / scattering particle size distribution measuring apparatus immediately after preparing the composition of the present invention.

  The amount of the component (a) suspended in water in the composition of the present invention is 1% by mass or more, preferably 1 to 70% by mass, more preferably 5 to 60% by mass, based on the entire composition of the present invention. More preferably, it is 20-50 mass%.

  Further, the composition of the present invention does not contain an inorganic compound other than component (a) as a suspended matter. Examples of the inorganic compound include zinc-indium composite oxide, lead-zinc composite oxide, lead-zinc-niobium composite oxide, bismuth-zinc-niobium composite oxide, barium-zinc-tantalum composite oxide, tin-zinc. Composite oxides, lithium-added zinc oxide, zinc-added ferrite (iron-zinc composite oxide), titanium-zinc composite oxide, zinc-oxide inorganic composites such as silicon-zinc composite oxide, zinc chromate, zinc phosphate Zinc molybdate, zinc sulfide; inorganic oxides such as titanium oxide, silica and iron oxide, barium sulfate, calcium carbonate and the like.

  On the other hand, the composition of the present invention may contain an organic compound or an organometallic compound other than the component (a) as a suspension. For example, zinc stearate can be used.

Component (b) used in the present invention is at least one selected from the group consisting of citric acid and salts thereof.
Citric acid is a hydroxy acid having three carboxyl groups, and the aqueous solution is weakly acidic (pKa = 2.87). As salts of citric acid, alkali metal salts such as sodium, potassium and lithium; alkaline earth metal salts such as calcium, magnesium and barium; ammonium salts, secondary to tertiary alkylamine salts, quaternary ammonium salts; iron, copper Metal salts such as manganese, zinc and aluminum. In addition, examples of the salt of citric acid include a double salt containing a plurality of types of cations. Among these, a water-soluble salt having a water solubility (20 ° C.) of 1% by mass or more, specifically, sodium dihydrogen citrate, disodium hydrogen citrate, ammonium dihydrogen citrate, diammonium hydrogen citrate, and Iron (III) citrate is preferred.

  The amount of the component (b) contained in the composition of the present invention is 0.1 to 100 parts by weight, preferably 0.5 to 50 parts by weight, more preferably 100 parts by weight of the suspended matter component (a). 1 to 10 parts by mass. The amount of the component (b) contained in the composition of the present invention is preferably 0.01 to 10% by mass, more preferably 0.1 to 1% by mass with respect to the entire composition of the present invention.

  The composition of the present invention contains at least water as a suspension medium. Although the content rate of water is not specifically limited, Preferably it is 10 mass% or more with respect to the whole composition of this invention, More preferably, it is 30 mass% or more. In the present invention, it is preferable to use only water as the suspending medium, but other suspending medium such as a polar organic solvent may be used in combination with water depending on the application. Examples of polar organic solvents include lower alcohols such as ethanol and isopropanol; glycol solvents such as ethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, and glycerin; ketone solvents such as acetone, methyl ethyl ketone, and propylene carbonate; dimethyl sulfoxide, acetonitrile Etc.

  The composition of the present invention can further contain a surfactant. When a zinc oxide-based organic complex is included as a suspended matter, suspension stability can be further improved by adding a surfactant. However, when only zinc oxide is contained as a suspended matter, sufficient suspension stability can be obtained without containing a surfactant. Therefore, it is preferable not to contain a surfactant.

Examples of the surfactant include alkyl ethers added with polyoxyethylene, higher fatty acid esters added with polyoxyethylene, sorbitan higher fatty acid esters added with polyoxyethylene, and tristyryl phenyl ether added with polyoxyethylene. Nonionic surfactants, alkyl benzene sulfonates, sulfate esters of higher alcohols, alkyl naphthalene sulfonates, lignin sulfonates, formaldehyde condensates of alkyl naphthalene sulfonates, and the like. These surfactants can be used alone or in combination of two or more.
The amount of the surfactant that can be contained in the composition of the present invention is 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less, based on the entire composition of the present invention. When the zinc oxide organic complex is included as the suspended matter, the lower limit amount of the surfactant is preferably 1% by mass or more based on the entire composition. Moreover, the preferable amount of the surfactant is preferably 100 parts by mass or less, more preferably 10 parts by mass or less, with respect to 100 parts by mass of the suspended component (a). Furthermore, the preferable amount of the surfactant is preferably 500 parts by mass or less with respect to 100 parts by mass of the component (b).

  When the composition of the present invention further contains an organic thickener, the suspension stability of the suspension component (a) can be further improved.

  Organic thickeners include thickened polysaccharides such as sodium alginate, starches, dextrin, tara gum, guar gum, xanthan gum and locust bean gum; methylcelluloses, ethylcelluloses, hydroxypropylmethylcelluloses, hydroxypropylethylcelluloses, hydroxycelluloses And cellulose derivatives. Of these, xanthan gum is particularly preferred.

  The composition of the present invention has a pH immediately after preparation of 6.5 or more, preferably 6.5 or more and 9 or less, more preferably 7 or more and 9 or less, from the viewpoint of suspension stability of the suspension component (a). . When the pH is less than 6.5, the suspended solid component (a) may be dissolved. Moreover, from the viewpoint that the viscosity of the composition of the present invention is low, the pH of the composition of the present invention after being left at 54 ° C. for 14 days is preferably 7 or more and 9 or less.

  The composition of the present invention may contain an antioxidant, a light stabilizer, a fragrance, an antifoaming agent and the like, if necessary.

  The composition of the present invention is not particularly limited by the production method. For example, by combining the suspension component (a), component (b), water, and other components and stirring vigorously; or, combining the suspension component (a) and water, It can be obtained by adding component (b) and other components and stirring vigorously. Strong stirring can be performed using a stirrer such as a homogenizer, or a wet pulverizer such as a ball mill, a bead mill, or a pin mill.

As a manufacturing method of this invention composition, the following method is preferable, for example. (1) A method of producing a suspension by suspending the suspended solid component (a) in water and adding and mixing the component (b); (2) mixing the suspended solid component (a) with water and wet Method of pulverizing and adding component (b) and mixing; (3) Mixing suspension component (a) and water, wet pulverizing, adding aqueous solution of component (b) and mixing (4) A method of producing the suspension by mixing the suspended component (a), the component (b), and water, followed by wet pulverization.
In addition, you may add the process of mixing components, such as surfactant, an organic thickener, an organic solvent, an antifoamer, to each said process suitably. Among the above methods, from the viewpoint that a particularly stable aqueous suspension composition can be produced, a method comprising a step of wet-pulverizing the suspended solid component (a), that is, (2), (3) or ( The method 4) is preferable, and the method (2) or (3) is more preferable.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples. In addition, what was described as "part" is a mass part unless there is particular notice.

Example 1
Zinc oxide 30.0 parts, New Calgen C-200 (manufactured by Takemoto Yushi Co., Ltd.) 1.5 parts, Surfynol 104 (manufactured by Air Products) 0.1 part, Road Pole G (manufactured by Rhodia Nikka Co., Ltd.) 0.2 Part and 0.6 part of an antiseptic were suspended in 50.2 parts of tap water. This was wet pulverized under the following conditions using a Dino mill (MULTI LAB type).
Container capacity: 300 mL, slit: 0.2 mm, supply speed: 100 g / min,
Number of grinding: 1 time, agitator: 64 mm urethane, angular velocity: 12 m / s,
Beads: 260 mL of φ0.5 mm glass beads (filling rate 85%).

  An aqueous suspension composition having a pH of 6.9 was prepared by adding 6.0 parts of tap water and 0.5 part of citric acid (anhydrous) to the wet milled product and mixing.

(Fluidity test)
10 g of the aqueous suspension composition immediately after preparation was put into a 13.5 ml screw tube bottle (mouth inner diameter 14.5 mm, trunk diameter 24 mm, total length 50 mm) and covered. If the tip of the moving surface of the aqueous suspension composition reaches the lid of the screw tube bottle within 2 seconds after leaving the screw tube horizontally, “excellent fluidity” takes more than 2 seconds. X was judged as “poor fluidity”. Further, the aqueous suspension composition immediately after preparation determined to be “poor fluidity” is put into a screw tube bottle as described above, covered, the screw tube bottle is leveled, and 30 reciprocations per second in the vertical direction. When the tip of the moving surface of the aqueous suspension composition has reached the lid of the screw tube within 2 seconds after being left and left for 10 seconds with the lid of the screw tube bottle facing upward, It was judged as “good liquidity”.
Next, the fluidity of the aqueous suspension composition that was allowed to stand at room temperature for 3 days was evaluated by the same method as described above. Furthermore, the fluidity of the aqueous suspension composition that had been allowed to stand at 54 ° C. for 14 days was evaluated by the same method as described above. The results are shown in Table 1.

(Particle size measurement)
About the aqueous suspension composition immediately after preparation and the aqueous suspension composition left to stand at 54 ° C. for 14 days, using a laser diffraction scattering method particle size distribution measuring apparatus (LS 13 320 manufactured by Beckman Coulter, Inc.), volume basis. The average particle size in the particle size distribution was measured.

Examples 2-4 and Comparative Examples 1-7
An aqueous suspension composition was prepared in the same manner as in Example 1 except that citric acid (anhydrous) was changed to the organic acid shown in Table 1. The aqueous suspension composition was evaluated in the same manner as in Example 1. The results are shown in Table 1.

  As Table 1 shows, the aqueous suspension composition (Example) containing citric acid or a salt thereof has excellent fluidity. An aqueous suspension composition containing an organic acid other than citric acid (Comparative Example) has poor fluidity after standing for a long time.

Example 5
40.0 parts of zinc oxide, 0.5 parts of disodium hydrogen citrate hemihydrate and 0.1 part of preservative were suspended in 39.4 parts of tap water. This was wet pulverized under the following conditions using a Dino mill (MULTI LAB type).
Container capacity: 300 mL, slit: 0.2 mm, supply speed: 100 g / min,
Number of grinding: 1 time, agitator: 64 mm urethane, angular velocity: 12 m / s,
Beads: 260 mL of φ0.5 mm glass beads (filling rate 85%).

  The wet pulverized product was mixed with 19.8 parts of tap water and 0.2 part of Rhodopol G (manufactured by Rhodia Nikka Co., Ltd.) to prepare an aqueous suspension composition.

  The pH of the aqueous suspension composition immediately after preparation was 9.5. The pH of the aqueous suspension composition that was allowed to stand at 54 ° C. for 14 days was 9.0.

  For the aqueous suspension composition immediately after preparation and the aqueous suspension composition left to stand at 54 ° C. for 14 days, the viscosity was measured at 25 ° C. and 30 rpm using a B-type viscometer (manufactured by Toki Sangyo Co., Ltd., model RB80). It was measured. The viscosity of the aqueous suspension composition immediately after preparation was 427 mPa · s. The viscosity of the aqueous suspension composition which was allowed to stand at 54 ° C. for 14 days was 355 mPa · s.

  About the aqueous suspension composition immediately after preparation and the aqueous suspension composition left to stand at 54 ° C. for 14 days, using a laser diffraction scattering method particle size distribution measuring apparatus (LS 13 320 manufactured by Beckman Coulter, Inc.), volume basis. The average particle size in the particle size distribution was measured. The average particle size of the aqueous suspension composition immediately after preparation was 0.35 μm. The average particle size of the aqueous suspension composition which was allowed to stand at 54 ° C. for 14 days was 0.61 μm.

(Layer separation rate)
The aqueous suspension composition was placed in a 110 ml screw tube bottle and allowed to stand at 54 ° C. for 14 days. Next, the height of the supernatant was measured. The ratio of the height of the supernatant to the height of the aqueous suspension composition placed in the screw tube bottle was calculated as the layer separation rate (%). The layer separation rate was 23%.

Example 6
HYBRICIDE-94S (composition composed of zinc pyrithione / zinc oxide complex and zinc oxide, manufactured by KOLON LIFE SCIENCE) 40.0 parts, New Calgen C-200 (manufactured by Takemoto Yushi Co., Ltd.), 2 parts, Surfynol 104 (air (Products) 0.1 parts, Road Pole G (Rhodia Nikka Co., Ltd.) 0.25 parts, and preservative 0.8 parts were suspended in tap water 36.85 parts. This was wet pulverized under the following conditions using a Dino mill (MULTI LAB type).
Container capacity: 300 mL, slit: 0.2 mm, supply speed: 100 g / min,
Number of grinding: 1 time, agitator: 64 mm urethane, angular velocity: 12 m / s,
Beads: 260 mL of φ0.5 mm glass beads (filling rate 85%).

15 parts of tap water was mixed with the wet milled product. Next, 0.5 part of disodium hydrogen citrate hemihydrate 0.5 part and 4.5 parts of tap water were added and mixed to prepare an aqueous suspension composition.
The layer separation rate, average particle diameter and viscosity were calculated in the same manner as in Example 5. The results are shown in Table 2.

Comparative Example 8
An aqueous suspension composition was prepared in the same manner as in Example 6 except that disodium hydrogen citrate hemihydrate was changed to sodium acetate. The layer separation rate, average particle diameter and viscosity were calculated in the same manner as in Example 5. The results are shown in Table 2.

Comparative Example 9
An aqueous suspension composition was prepared in the same manner as in Example 6, except that 0.5 parts of disodium hydrogen citrate hemihydrate and 4.5 parts of tap water were changed to 5.0 parts of tap water. did. The layer separation rate, average particle diameter and viscosity were calculated in the same manner as in Example 5. The results are shown in Table 2.

Example 7
An aqueous suspension composition was prepared in the same manner as in Example 6 except that disodium hydrogen citrate hemihydrate was changed to citric acid. The layer separation rate, average particle diameter and viscosity were calculated in the same manner as in Example 5. The results are shown in Table 2.

  As Table 2 shows, the aqueous suspension composition (Example) containing citric acid or a salt thereof has a small particle size of suspension and a low viscosity. An aqueous suspension composition (comparative example) containing an organic acid other than citric acid has a large particle size and high viscosity.

Claims (4)

1% by mass or more of at least one suspension component (a) selected from the group consisting of zinc oxide and a zinc oxide-based organic complex, and at least one component (b) selected from the group consisting of citric acid and salts thereof Contains water,
A surfactant can be contained in an amount of 10% by mass or less,
The amount of the component (b) is 0.1 to 100 parts by mass with respect to 100 parts by mass of the suspended solid component (a),
A composition having a pH of 6.5 or more and containing no inorganic compound other than component (a) as a suspension.   The composition according to claim 1, wherein the suspended solid component (a) is a zinc oxide-based organic complex composed of zinc pyrithione and zinc oxide.   The composition according to claim 1, wherein the suspended solid component (a) is zinc oxide and the content of the surfactant is 0% by mass. Mixing at least one suspension component (a) selected from the group consisting of zinc oxide and a zinc oxide-based organic complex, with water,
The resulting mixture is wet crushed,
The method for producing a composition according to any one of claims 1 to 3, comprising adding at least one component (b) selected from the group consisting of citric acid and a salt thereof to the wet pulverized product.