JPH09100460A - Ultraviolet ray-blocking agent and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a lightweight ultraviolet rays-blocking agent capable of readily producing, excellent in ultraviolet rays-blocking properties, dispersibility and oil-absorbing property, free from toxicity, having safety and useful in fields of coating materials, adhesives, ink, etc. by attaching specific metal oxide particles to the surface of specific amorphous silica secondary particles. SOLUTION: This ultraviolet rays-blocking agent is obtained by attaching (B) particles of cerium oxide, titanium oxide, zinc oxide or iron oxide to the surface of (A) secondary particles of nearly spherical amorphous silica obtained by three dimensionally and irregularly entangling needle-like, plate-like or foil- like amorphous silica primary particles (A1 ) or amorphous silica primary particles (A2 ) obtained by irregularly attaching many granular amorphous silica to needle-like, plate-like or foil-like amorphous silica. The blocking agent is obtained by bringing, e.g. the component A into contact with either one of (i) a metal salt of cerium, titanium, zinc or iron and (ii) an alkali (earth) metal hydroxide or ammonium and then bringing the component A into contact with the other one and filtering and drying the product.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an ultraviolet shielding agent and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, various ultraviolet shielding agents have been developed and used for various purposes such as paints, adhesives, resins, inks, papermaking, and cosmetics. The safety of the organic ultraviolet shielding agent is a problem due to its toxicity. on the other hand,
Inorganic ultraviolet shielding agents such as titanium oxide and cerium oxide have also been used, but this has a problem in dispersibility when blended with a resin or the like.

[0003] As a means for improving the disadvantages of the above-mentioned inorganic ultraviolet shielding agent, there is known a granular silica made of natural silica, synthetic silica, glass or the like having a refractive index of 1.45 to 1.6 and an average particle diameter of 0.1 to 50 µm. There is known an ultraviolet shielding agent in which an insoluble cerium compound is fixed on the surface of pigment particles and the whole is coated with silica (Japanese Patent Application Laid-Open No. 7-207251).

[0004] However, this involves the formation of coarse aggregates when fixing the insoluble cerium compound on the surface of the granular silica pigment and coating the whole with silica.
In order to function as a pigment or the like, a crushing process is required.

[0005] Further, in order to exert an ultraviolet ray shielding effect, it must be finally fired at 200 to 1000 ° C.

[0006] In particular, an ultraviolet shielding agent using natural silica as a silica granular pigment has a high bulk density, a small oil absorption, and exhibits a sticky feeling.

As described above, in the above-mentioned technology, not only the production is complicated, but also because of its high bulk density, there is a limit in reducing the weight even when blended with resin or paper. Further, since the oil absorption is small, it cannot be expected to have the effect of adjusting the viscosity when blended in paints, resins, adhesives, inks and the like, or the effect of preventing strike-through of the ink when blended in paper. Furthermore, when incorporated into cosmetics such as foundations, the amount of sebum absorbed is small and makeup is likely to be lost, giving a feeling of stickiness and not very good touch.

[0008]

SUMMARY OF THE INVENTION The main object of the present invention is to provide an ultraviolet shielding agent having a light weight, an excellent oil absorbing ability, and no feeling of stickiness and a method for producing the same.

[0009]

Means for Solving the Problems The present inventor has made extensive studies in view of the above-mentioned problems of the prior art, and as a result, for example, has been disclosed in Japanese Patent Publication No. 55-14809, Japanese Patent Publication No. 6-99139, and the like. Using a specific amorphous silica secondary particles, this is first contacted with any one of a metal salt of an inorganic ultraviolet shielding agent such as titanium oxide and cerium oxide and a hydroxide of an alkali metal, and then the other. It has been found that a desired ultraviolet shielding agent can be easily obtained in the comparative region by contact.

That is, they have found that a novel ultraviolet shielding agent having both the ultraviolet shielding effect and the above-mentioned properties can be obtained by using the above-mentioned specific amorphous silica secondary particles, without requiring calcination or the like. The present invention has been completed.

The present invention relates to the following ultraviolet shielding agent and a method for producing the same.

1. Needle-shaped, plate-shaped or foil-shaped amorphous silica primary particles or needle-shaped, plate-shaped or foil-shaped amorphous silica, and amorphous silica primary particles in which a large number of granular amorphous silica are irregularly adhered. At least one surface of at least one of cerium oxide, titanium oxide, zinc oxide and iron oxide is provided on at least the surface of the three-dimensionally irregularly entangled substantially spherical amorphous silica secondary particles.
UV shielding agent with seed particles attached.

2. Acicular, plate-shaped or foil-shaped amorphous silica primary particles are irregularly entangled three-dimensionally and are almost spherical amorphous silica secondary particles or needle-shaped, plate-shaped or foil-shaped amorphous Amorphous silica primary particles, in which a large number of granular amorphous silica particles are irregularly attached to porous silica, are three-dimensionally irregularly entangled. At least one of a metal salt of cerium, titanium, zinc and iron and at least one of a hydroxide of an alkali metal, a hydroxide of an alkaline earth metal and ammonia are contacted first, and then the other After contacting
A method for producing an ultraviolet shielding agent, comprising filtering and drying a product.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail along with its embodiments.

The secondary particles of the amorphous silica used in the present invention may be primary needle-like, plate-like or foil-like amorphous silica particles or non-crystalline needle-like, plate-like or foil-like amorphous silica particles. Amorphous silica primary particles with a large number of amorphous silica irregularly attached,
Substantially spherical amorphous silica secondary particles entangled three-dimensionally irregularly.

The needle-shaped, plate-shaped or foil-shaped amorphous silica primary particles usually have a length of about 1 to 50 μm and a width of 0.01 to 5 μm.
It has a size of about 0 μm, and the particle size of the granular amorphous silica adhered to the particles is usually about 5 to 300 nm.

The particle diameter of the secondary particles of the amorphous silica is usually about 2 to 150 μm, preferably about 2 to 50 μm, but there are some particles outside the above range depending on the raw materials and production conditions. The internal structure of the secondary particles includes a structure in which the amorphous silica primary particles are densely packed, a structure in which the particles are sparse, a structure in which the particles are hollow, and the like. I do. These structures can be appropriately selected according to the application and the like.

In addition, silica other than the above, for example,
In the case of using the porous silica microspheres disclosed in JP-A-58408, even if the inorganic ultraviolet shielding agent is carried on the porous silica microspheres in the same manner as described above, it does not adhere well. The desired ultraviolet shielding agent cannot be obtained.

As a method for producing the above-mentioned amorphous silica secondary particles, for example, the secondary particles of calcium silicate crystals to which an alkali silicate is added, if necessary, are carbonated in the presence of water, and further subjected to an acid treatment. For example, in Japanese Patent Publication No. 55-14809, Japanese Patent Publication No. 6-99139.
The method disclosed in Japanese Unexamined Patent Publication (Kokai) No. HEI 10-301 is suitably used. In this case, if the primary particles constituting the secondary particles of the calcium silicate crystal are acicular crystals, the amorphous silica primary particles obtained therefrom will be acicular, and if the primary particles of the calcium silicate crystal are plate-like. The primary particles of amorphous silica become plate-like. That is, the shape of the obtained amorphous silica primary particles is determined by the shape of the primary particles of the calcium silicate crystal. For example, zonotolite, foshagitite, wollastonite and the like can be obtained in the form of needles, tobermorite, gyrolite and the like in the form of plates, and quasicrystalline calcium silicate and the like in the form of foils.

The amorphous silica secondary particles have at least one of cerium oxide, titanium oxide, zinc oxide and iron oxide adhered to the surface thereof. The term “adhesion” as used in the present invention means a state where cerium oxide or the like is not separated from the amorphous silica secondary particles by at least ultrasonic dispersion.

The cerium oxide, titanium oxide, zinc oxide and iron oxide to be adhered to the above-mentioned amorphous silica secondary particles may be used alone or in combination of two or more. The supported amount when used alone or when used in combination is usually about 1 to 40% by weight, preferably about 5 to 30% by weight. If it is less than 1% by weight, the effect of shielding ultraviolet rays is not effective, and if it exceeds 40% by weight, it becomes difficult to fix the particles to the amorphous silica secondary particles. Become.
Also, the ultraviolet shielding effect is reduced.

In the production method of the present invention, the substantially spherical amorphous silica secondary particles or needles are obtained by three-dimensionally entanglement of needle-like, plate-like or foil-like amorphous silica primary particles. Shape,
Substantially spherical amorphous silica consisting of amorphous silica in which a large number of granular amorphous silica is irregularly attached to plate-like or foil-like amorphous silica Use secondary particles.

The amorphous silica secondary particles can be used in the form of a powder. However, if necessary, they may be used by being dispersed in a solvent such as water in advance. When dispersing, the content can be set appropriately.

In the presence of water, at least one metal salt of cerium, titanium, zinc and iron, an alkali metal hydroxide, an alkaline earth metal hydroxide and After contacting at least one of ammonia first, the other is contacted.

As the above-mentioned metal salt, it is preferable to use a water-soluble metal salt, and for example, chlorides, nitrates, sulfates and the like of the above-mentioned metals can be preferably used. The contacting method is not particularly limited, and examples thereof include a method in which the metal salt is dissolved or dispersed in water and mixed with the amorphous silica secondary particles while stirring. Further, the above mixing may be carried out at room temperature, or may be carried out by heating if necessary.

The amount of the metal salt added may be such that the amount of cerium oxide, titanium oxide, zinc oxide, iron oxide, etc. carried in the ultraviolet shielding agent of the present invention finally becomes 1 to 40% by weight. Accordingly, the concentration of the aqueous solution or dispersion of the metal salt may be appropriately determined.

When at least one of an alkali metal hydroxide, an alkaline earth metal hydroxide and ammonia is brought into contact, when it is reacted with the above-mentioned metal salt, other than cerium, titanium, zinc and iron compounds, It is preferable to select a compound that does not generate a compound insoluble in water. For example, when chloride is used as the metal salt, sodium hydroxide, potassium hydroxide, calcium hydroxide and the like are preferably used.

As a method of contact, mixing may be performed in the same manner as in the above treatment. These may be used in advance as an aqueous solution or an aqueous dispersion. In the case of ammonia, it can be used as aqueous ammonia.

The addition amount of at least one of the alkali metal hydroxide, the alkaline earth metal hydroxide and the ammonia can be determined as appropriate, but is usually not less than the neutralization equivalent of the metal salt. Good.

Next, the product is filtered and dried according to a conventional method. The higher the drying temperature, the higher the production efficiency can be. However, if the drying temperature is too high, the ultraviolet shielding effect may be impaired. Therefore, the drying temperature is usually 300 ° C. or lower, preferably less than 200 ° C.

According to this treatment, the ultraviolet shielding agent of the present invention, in which particles comprising at least one of cerium oxide, titanium oxide, zinc oxide and iron oxide are adhered to at least the surface of the amorphous silica secondary particles. can get.

In the production method of the present invention, it is essential that one of the metal salt and the hydroxide of an alkali metal is first brought into contact with the amorphous silica secondary particles, When the amorphous silica secondary particles are brought into contact with a mixture of a hydroxide and the like, cerium oxide,
Titanium oxide, zinc oxide and iron oxide cannot be successfully attached and fixed to the amorphous silica secondary particles.

Also, a powder of an inorganic ultraviolet shielding agent such as cerium oxide is added to the raw material slurry in the production process of the amorphous silica secondary particles, and the inorganic ultraviolet shielding agent such as cerium oxide is added to the amorphous silica secondary particles. When the particles are included in the secondary particles, a desired ultraviolet shielding effect cannot be obtained.

[0034]

According to the production method of the present invention, specific amorphous silica secondary particles are used as a base material for supporting an inorganic ultraviolet shielding agent such as cerium oxide, titanium oxide, zinc oxide and iron oxide. By selecting, an ultraviolet ray shielding agent can be obtained by a relatively simple method without requiring a complicated manufacturing process such as baking as in the prior art.

Further, the ultraviolet ray shielding agent of the present invention has an excellent ultraviolet ray shielding effect, and is nontoxic and safe, has good dispersibility, is light in weight, has excellent oil absorbing ability, and has a sticky property, unlike organic shielding agents. Since it has no feeling, it can be applied in various fields such as paints, adhesives, resins, inks, papermaking, cosmetics, and the like.

[0036]

The present invention will be described below with reference to examples and comparative examples.

EXAMPLE 1 A substantially spherical amorphous silica obtained by irregularly entangled three-dimensionally with primary amorphous silica particles in which a large number of granular amorphous silica particles adhere to needle-like amorphous silica particles irregularly. Hollow amorphous silica secondary particles (particle size: 4 to 25 μm) were dispersed in water, a predetermined amount of a cerium chloride aqueous solution was mixed therein, and then a neutralization equivalent amount of a sodium hydroxide aqueous solution was added.

This was washed with filtered water and dried at 150 ° C., and cerium oxide was added in an amount of 0, 5, 10, 2 to the total solid content.
The powder sample No. consisting of amorphous silica secondary particles supported at 0, 30, and 45% by weight. 1 to 6 were obtained.

When these powder samples were observed with a scanning electron microscope, it was confirmed that cerium oxide particles had adhered to the surface of the amorphous silica secondary particles.

Next, each of these powder samples was
g in a test tube, 20 g of distilled water was added thereto, and the mixture was ultrasonically dispersed for 1 hour, allowed to stand still, and the powder sample precipitated at the bottom of the test tube was observed. For 2 to 5, cerium oxide remained attached to the amorphous silica secondary particles without being separated into cerium oxide and amorphous silica secondary particles.

On the other hand, the powder sample No. In No. 6, the separation of cerium oxide was recognized, and it was confirmed that some of the cerium oxides did not sufficiently adhere to the amorphous silica secondary particles. Table 1 shows the powder sample No. It shows the physical properties of 1 to 6.

[0042]

[Table 1]

The above physical properties were measured by the following methods.

1) Bulk density: According to the method of JIS K 1464.

2) Oil absorption: In accordance with JIS K 5101.

3) Light transmittance: A powder is added so as to be 0.04% by weight based on ethylene glycol (special grade of reagent), and the mixture is stirred and mixed to prepare a uniform dispersion. It was filled in a cell for measurement and measured with a spectrophotometer (UV-260 manufactured by Shimadzu Corporation). 4) Dispersibility: 50 g of nitrocellulose lacquer was weighed into a 100 ml beaker, 3% by weight of powder was added thereto, and the mixture was stirred for 5 minutes using a glass rod, and the state of dispersion was visually observed.

Further, the powder sample (Nos. 2 to 5) was put on the back of the hand and the tactile sensation was observed. As a result, it was found that there was no stickiness, it was smooth, the touch was good, and the elongation was good. On the other hand, for powder sample No. As described above, the adhesive strength of cerium oxide to the amorphous silica secondary particles was weak, and the ultraviolet ray shielding effect was also poor.

Example 2 Using substantially spherical hollow amorphous silica secondary particles (particle diameter of 4 to 25 μm) in which needle-like amorphous silica primary particles are irregularly entangled three-dimensionally. In the same manner as in Example 1, powder sample no. 7 was obtained.
Table 2 shows the physical properties of this powder sample.

[0049]

[Table 2]

The powder sample, like the powder sample of Example 1, had no stickiness, was smooth, had a good touch, and had good spreadability.

Example 3 The same operation as in Example 1 was carried out except that an aqueous solution of titanium chloride, an aqueous solution of zinc chloride or an aqueous solution of iron chloride was used in place of the aqueous cerium chloride solution. Powder sample No. 20 in which titanium oxide, zinc oxide or iron oxide was supported at 20% by weight. 8 to 10 were obtained.
Table 3 shows the physical properties of this powder sample.

[0052]

[Table 3]

As in the case of Example 1, each powder sample had no stickiness, was smooth, had a good touch, and had good spreadability.

Comparative Example 1 In place of the amorphous silica secondary particles of Example 1, a silica microcapsule (particle size: 0.5, manufactured by Suzuki Yushi Kogyo KK) was used.
-20% by weight of cerium oxide in the same manner as in Example 1 using ゴ 6.0 μm, trade name “Godball” B-6C).
The powder sample no. 11 was obtained. Table 4 shows the physical properties of this powder sample.

[0055]

[Table 4]

When this powder was subjected to ultrasonic dispersion in the same manner as in Example 1, separation of cerium oxide and silica microcapsules occurred, and it was found that cerium oxide was not sufficiently adhered. Also, as can be seen from the above table,
This powder had the same ultraviolet shielding effect as that of the present invention and had no stickiness, but had a higher bulk density and a lower oil absorption than those of the examples.

Comparative Example 2 In place of the amorphous silica secondary particles of Example 1, the refractive index was 1.
Using 55 natural silica (particle diameter: 0.1 to 10 μm), this is dispersed in water, a predetermined amount of a cerium chloride aqueous solution is mixed while heating to 80 ° C., and then a sodium hydroxide aqueous solution is neutralized by an equivalent weight. After the addition and mixing, the mixture was filtered, washed with water, and dried to obtain a lump supporting 20% by weight of cerium oxide.

Subsequently, the lump was pulverized, dispersed in water, and heated to 80 ° C., mixed with sodium silicate No. 3, neutralized by adding sulfuric acid, filtered, washed with water and dried. Then, the mixture was pulverized to obtain natural silica carrying 20% by weight of cerium oxide entirely coated with silica. Then 500
C. for 2 hours. I got 12. Table 5 shows the physical properties of this powder sample.

[0059]

[Table 5]

As can be seen from the above table, although the ultraviolet shielding effect of this powder is similar to that of the present invention,
The bulk density was high, the oil absorption was small, the dispersibility was poor, and there was stickiness.

When the powder sample of the present invention obtained in Example 1 of the present application was fired at 500 ° C. for 2 hours in the same manner as in Comparative Example 2, it was found that the ultraviolet ray shielding effect was reduced.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Naomi Kawahara 4064-1, Kitanuma, Noda Nitta, Hozumi-cho, Motosu-gun, Gifu Prefecture, Japan Insulation Co., Ltd. 4064-1, Kitanuma, Noda-Shinden, Hozumi-cho, Motosu-gun, Gifu Prefecture

Claims (2)

[Claims] 1. An amorphous phase comprising a plurality of needle-shaped, plate-shaped or foil-shaped amorphous silica primary particles or a needle-shaped, plate-shaped or foil-shaped amorphous silica to which a large number of granular amorphous silica are irregularly attached. At least one particle of cerium oxide, titanium oxide, zinc oxide and iron oxide is formed on at least the surface of the substantially spherical amorphous silica secondary particles in which porous silica primary particles are irregularly entangled three-dimensionally. UV shielding agent to which is adhered. 2. A substantially spherical amorphous silica secondary particle comprising needle-like, plate-like or foil-like amorphous silica primary particles three-dimensionally entangled, or acicular, plate-like or Substantially spherical amorphous silica particles composed of three-dimensionally irregularly entangled amorphous silica primary particles consisting of foil-like amorphous silica and a large number of irregularly attached granular amorphous silica In the presence of water, at least one of cerium, titanium, zinc and iron and at least one of an alkali metal hydroxide, an alkaline earth metal hydroxide and ammonia A method for producing an ultraviolet shielding agent, comprising contacting the other, then contacting the other, and then filtering and drying the product.