JPH0621024B2 - Flake ultraviolet absorbing synthetic mica - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a flake-like UV absorbing synthetic mica, and in particular, by mixing with cosmetics, paints or plastics,
The present invention relates to an ultraviolet absorbing synthetic mica capable of imparting an excellent ultraviolet absorbing effect, and to a flaky ultraviolet absorbing synthetic mica having extremely high whiteness.

[Prior Art] Conventionally, as an ultraviolet absorber used for cosmetics and plastics, there is an ultraviolet absorber composed of an organic compound such as a benzophenone type, a benzotriazole type, a salicylate type or an acrylonitrile type.

Further, JP-A-58-19379 has a visible light-transmitting property and an ultraviolet-absorbing property mainly containing an artificial mica containing one or more of nickel, cobalt, manganese, titanium, vanadium and barium. UV absorbers have been proposed. Furthermore, the inventors of the present invention have used metal oxides of 0.1% as a UV-absorbing flake glass having a high UV-absorbing effect.
It has been proposed to contain 3 to 10% by weight (Japanese Patent Laid-Open No. 63-
307142).

[Problems to be Solved by the Invention] Of the above-mentioned conventional products, all of the ultraviolet absorbers made of organic compounds are decomposed by ultraviolet rays, so that not only the effect does not last, but when added to cosmetics,
It has a drawback that it may cause an allergic reaction to the skin.

Further, among the ultraviolet absorbers disclosed in JP-A-58-19379, those containing nickel, cobalt and manganese have an absorption coefficient several tens of times higher in the visible region than in the ultraviolet region, and the visible light transmittance is high. Since the rate is low, it is difficult to obtain high whiteness. Further, in the case of containing titanium and barium, the absorption coefficient is substantially extremely low in both ultraviolet and visible, and a high ultraviolet absorbing effect cannot be obtained. Vanadium is the only component having a high absorption in the ultraviolet region and a low absorption in the visible region, but vanadium pentoxide has the drawback that it causes problems during production and use because of its toxicity.

On the other hand, the glass flakes of JP-A-63-307142 have high absorption in the ultraviolet region and low absorption in the visible region,
Although it is a near-ideal ultraviolet absorber, it has a disadvantage that productivity decreases when the thickness of flakes is 1 micron or less.

The present invention solves the conventional problems described above, and provides an ultraviolet-absorbing synthetic mica that has high weather resistance, is harmless to the human body, has sufficient whiteness and a high ultraviolet-absorbing effect, and is also highly productive. With the goal.

[Means for Solving the Problems] The flaky ultraviolet absorbing synthetic mica of claim (1) is Fe.
2-18% by weight in terms of Fe ₂ O ₃ content, divalent Fe
Fe is 0.8 wt% or less in terms of FeO, and Fe with respect to the sum of the FeO-converted value and the Fe ₂ O ₃ -converted value.
The weight ratio of O conversion value is Is characterized in that.

The flaky ultraviolet absorbing synthetic mica according to claim (2) is the same as that according to claim (1), in which Ce is added in an amount of 0.5 to 0.5 in terms of CeO _2.
It is characterized by containing 13% by weight.

The present invention will be described in detail below.

In the flake ultraviolet absorbing synthetic mica of claim (1), when the Fe content is less than 2% by weight in terms of Fe ₂ O ₃ ,
The Fe content is too small to obtain a sufficient ultraviolet absorbing effect. When the Fe content exceeds 18 wt% in terms of Fe ₂ O ₃ , the coloring of the synthetic mica increases and the whiteness decreases. Therefore, the Fe content is ₂ to 18 wt% in terms of Fe ₂ O ₃ .

Further, if the divalent Fe content exceeds 0.8% by weight in terms of FeO, a sufficiently high whiteness cannot be obtained, and the ultraviolet ray absorbing effect becomes low. Therefore, the divalent Fe content is 0.8% by weight or less, preferably 0.5% by weight or less in terms of FeO.

Furthermore, the Fe ₂ O ₃ conversion value of all Fe and the Fe of divalent Fe
O conversion value is the weight ratio, The value is When the above ratio exceeds 0.1, the divalent Fe content with respect to the total Fe content increases, and the whiteness and the ultraviolet absorbing effect are impaired. Therefore, the weight ratio is 0.1 or less.

In the flake ultraviolet absorbing synthetic mica according to claim (2), when the Ce content is less than 0.5% by weight in terms of CeO ₂ , sufficient effect by Ce cannot be obtained. Conversely, undesirable Ce content and CeO ₂ exceeds 13 wt% in terms of CeO ₂ precipitates separated. Therefore, Ce
The content is 0.5 to 13% by weight in terms of CeO ₂ .

The method for producing the flake ultraviolet absorbing synthetic mica of the present invention will be described below.

The flake ultraviolet absorbing synthetic mica of claim (1) is obtained by melting a synthetic fluorine mica composition containing 2 to 18% by weight of Fe in terms of Fe ₂ O ₃ in air at a temperature of 1400 to 1500 ° C. Thereafter, the crystallized product obtained by slow cooling is pulverized to a particle size of about 100 μm or less, and a magnetically strong portion is separated and removed by magnetic separation to obtain a weakly magnetic portion.

That is, according to the research conducted by the present inventors, the degree of magnetism of synthetic mica containing Fe depends on the content of FeO, and a black crystal seed having a large FeO content has a smaller FeO content than a crystal seed having a high whiteness. It was confirmed that the magnetism was strong. Therefore, by utilizing this strength of magnetism to separate and remove black crystals having strong magnetism by a method called magnetic separation, crystals having weak magnetism, that is, FeO content is small and whiteness is high, is collected. can do. In the magnetic separation, if the synthetic mica is in the form of powder having a particle size of about 100 μm or less, the magnetic separation can be easily and efficiently performed.

The flake ultraviolet absorbing synthetic mica according to claim (1) is a crystallized material obtained by pulverizing the above-mentioned particle size of about 100 μm or less in an oxidizing atmosphere such as air or oxygen in an amount of 300 to 900.
It can also be obtained by carrying out an oxidation treatment by holding at a temperature of 30 ° C. for 30 minutes to several tens of hours. By such heat treatment, even in a black crystal containing a large amount of FeO, the contained FeO is easily oxidized, most of it becomes trivalent Fe ₂ O ₃ , and the whiteness is remarkably improved.

In the synthetic mica, it was confirmed that the FeO content of black crystals and the FeO content of brown to almost colorless crystals were continuously changing. Therefore, in the above-mentioned magnetic separation or oxidation treatment, by appropriately adjusting the strength of the magnetic force or the oxidation treatment condition, a synthetic mica having a desired whiteness can be obtained.

In the present invention, it is most preferable to perform magnetic separation after performing the above-mentioned oxidation treatment.

The flaky ultraviolet absorbing synthetic mica according to claim (2) is 2 to
In producing a synthetic fluorine mica composition containing 18 weight percent of Fe ₂ O ₃ , it is 0.5 in terms of CeO _2.
A synthetic fluoromica composition containing -13% by weight of cerium oxide together with Fe ₂ O ₃ was melted in air at a temperature of 1400 ° C to 1500 ° C and then slowly cooled to obtain a crystallized product. It can be manufactured by pulverizing the compound to about 100 μm or less and separating and removing the strongly magnetized portion by magnetic separation in the same manner as described above to obtain the weakly magnetized portion.

The flake ultraviolet absorbing synthetic mica according to claim (2) can also be produced by performing an oxidation treatment in which the temperature is kept at 300 to 900 ° C. for 30 minutes to several tens hours instead of magnetic separation. It is preferable to carry out this oxidation treatment, preferably before magnetic separation.

When a synthetic fluorine mica composition containing CeO ₂ is heated and melted to produce an ultraviolet absorbing synthetic mica, a synthetic fluorine mica composition to which CeO ₂ is not added is heated and fused to produce an ultraviolet absorbing synthetic mica. CeO ₂ compared to the case
Since the content of eO in the synthetic fluoromica composition is reduced by the oxidation effect of, the yield of the ultraviolet-absorbing synthetic mica having high whiteness is greatly improved by magnetic separation.

[Operation] Synthetic mica obtained by melting in air the composition of synthetic fluorine phlogopite (KMg ₃ AlSi ₃ O ₁₀ F ₂ ) in which Al is replaced by Fe ³⁺ and then gradually cooling is usually a total iron oxide. Of these, 15 to 30% by weight of ferrous oxide (FeO), that is, divalent iron oxide is contained. (Nobuto Daimon "Industrial Chemistry Magazine" 55 ,
[6], pages 326-328, (1952)).

As a result of examining the whiteness (Hunter whiteness) of the synthetic mica, the present inventors have found that the whiteness directly decreases with an increase in the FeO content regardless of the content of Fe ₂ O ₃ . That is, the coloring of synthetic mica containing iron is almost F
In order to obtain a synthetic mica that is caused by eO and has a high degree of whiteness, that is, a small amount of absorption in the visible region, it is necessary to reduce the FeO content as much as possible.

Further, the present inventors have prepared raw materials as described above, melted, then, in the crystallized product obtained by slow cooling, black mica crystals and brown to colorless mica crystals are under slow cooling conditions. Although different, they are mixed in the size of several millimeters to several tens of millimeters and are entangled with each other. FeO content is high in black mica crystals, but FeO content in brown to colorless mica crystals. I found that there are few.

On the other hand, from the viewpoint of ultraviolet absorption effect, Fe ₂ O ₃ and FeO
The absorption wavelength peaks are different between and, but Fe ₂ O ₃ is
It exhibits almost twice the ultraviolet absorption of O, and the presence of Fe ₂ O ₃ is more effective than FeO from the viewpoint of the ultraviolet absorption effect.

The invention of claim (1) has been completed based on the above findings, and since the divalent iron oxide is reduced in the predetermined amount of iron oxide contained, ultraviolet absorption synthesis with high whiteness is achieved. Mica is provided.

On the other hand, CeO ₂ has the function of oxidizing FeO to form Fe ₂ O ₃ . That is, we have 2-18% by weight of F.
When a synthetic fluoromica composition containing e ₂ O ₃ is produced, the synthetic fluoromica composition containing 0.5 to 13% by weight of CeO ₂ at the same time as Fe ₂ O ₃ is melted in air and then slowly cooled. When the crystallized product obtained was investigated, it was found that the FeO content was smaller and the whiteness was higher than that of the crystallized product produced without containing CeO ₂ . This is because when the synthetic fluorine mica composition is melted, CeO ₂ becomes FeO in the melt.
It is thought that this is due to the oxidation of.

Moreover, CeO ₂ itself has the ability to absorb ultraviolet light, and C
Since eO ₂ does not absorb visible light, it is suitable for obtaining an ultraviolet absorbing synthetic mica having a high degree of whiteness. Furthermore, trivalent cerium has an absorption peak at 315 nm,
While absorbing UV rays of nm, trivalent iron is 300n
Since the ultraviolet absorption capacity rapidly increases at m or less, the ultraviolet absorption synthetic mica containing cerium oxide and iron oxide exhibits a significantly superior ultraviolet absorption capacity to the ultraviolet absorption synthetic mica containing only iron oxide.

The invention of claim (2) is based on such knowledge, and FeO is converted to Fe ₂ O by the oxidation action of CeO _2.
By further reducing the FeO content as ₃ , the whiteness of the ultraviolet absorbing synthetic mica is increased and the ultraviolet absorbing ability is significantly improved.

[Examples] Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples unless it exceeds the gist.

Examples 1 to 7 About 1 kg of the formulation shown in Table 1 was charged into a platinum crucible and melted in an electric furnace at 1450 ° C. for 2 hours.
Crystallization was carried out by transferring to a furnace maintained at 50 ° C and cooling to 950 ° C at a rate of 50 ° C per hour. Next, the crystallized product thus obtained was pulverized to prepare flaky fine particles having a thickness of 1 μm or less and a width of 50 μm or less.

The obtained flaky fine particles were subjected to magnetic separation and / or oxidation treatment as shown in Table 2 to obtain flaky ultraviolet absorbing synthetic mica. When the obtained flaky ultraviolet absorbing synthetic mica was analyzed, the total Fe content, the FeO content and the weight ratio were as shown in Table 2.

The ultraviolet transmittance and whiteness of each flaky ultraviolet absorbing synthetic mica were examined, and the results are shown in Table 2.

The magnetic separation and oxidation treatment methods are as follows. When performing the magnetic separation and oxidation treatment, the magnetic separation after the oxidation treatment was performed.

The ultraviolet transmittance and whiteness were determined by the following methods.

Magnetic separation: A sample attached to a commercially available horseshoe-shaped magnet was removed.

Oxidation treatment: A 5 g sample was placed in a porcelain crucible and held in an electric furnace for the temperature and time shown in Table 2.

Ultraviolet transmittance: The fine powder sample has a large light scattering effect, and it is difficult to measure an accurate value even when dispersed in various media. Here, thickness = 10 μm, λ = 320 nm based on the absorption coefficient of trivalent Fe in soda-lime glass
The estimated value at is shown.

Whiteness: The powder was put on a white slide glass as a binder (“SPB-10F · P” manufactured by Toshiba: main component CH ₃ COOC _4).
H ₉₎ was applied by adding, after drying, was measured by the measuring device through the glass (Nippon Denshoku Industries Co., "NO-504AA type").

Comparative Examples 1 to 4 In the same manner as in Example 1 except that the magnetic separation and the oxidation treatment were not performed, No. The total Fe content, the FeO content and the weight ratio, the ultraviolet transmittance and the whiteness of each of the flake particles 1 to 4 were examined, and the results are shown in Table 2.

As is clear from Table 2, the ultraviolet absorption synthetic mica of the present invention obtained by magnetic separation and / or oxidation treatment is Fe
As a result of the low O content, without impairing the ultraviolet absorption ability,
Whiteness (hunter) is increasing. That is, when comparing those having the same ultraviolet transmittance, the whiteness of the product of the present invention is significantly improved.

Examples 8 to 14 Sample No. Approximately 1 kg of the formulation shown in 5-9
Was charged into a platinum crucible, melted in an electric furnace at 1450 ° C. for 2 hours, then transferred to a furnace kept at 1400 ° C., and 950
Crystallization was performed by cooling to 0 ° C at a rate of 20 ° C per hour. Next, the crystallized product thus obtained was pulverized to prepare flaky fine particles having a thickness of 1 μm or less and a width of 50 μm or less.

The obtained flaky fine particles were subjected to magnetic separation or magnetic treatment after oxidation treatment as shown in Table 4 in the same manner as in Examples 1 to 7 to obtain flaky ultraviolet absorbing synthetic mica. The yield in magnetic separation is shown in Table 4. When the obtained flaky ultraviolet absorbing synthetic mica was analyzed, the total Fe content, the FeO content and the weight ratio were as shown in Table 2.

With respect to each flaky ultraviolet absorbing synthetic mica, the ultraviolet transmittance and whiteness were examined in the same manner as in Examples 1 to 7, and the results are shown in Table 4. The ultraviolet transmittance is
It is a value estimated based on the light absorption coefficient of trivalent iron and trivalent cerium in lime glass.

Comparative Examples 5 to 7 Sample No. The total Fe content, the FeO content and the weight ratio, the ultraviolet transmittance and the whiteness were examined in the same manner as in Example 8 except that the magnetic separation and the oxidation treatment were not performed. The results are shown in Table 4.

From Table 4, the synthetic mica obtained by adding CeO ₂ has a high yield by magnetic separation, and has a higher whiteness than the synthetic mica obtained without adding CeO ₂ even when magnetic separation and oxidation treatment are not performed. Further, it is recognized that the whiteness is further improved by further subjecting this to magnetic separation and oxidation treatment.

[Effects of the Invention] As described in detail above, the flaky ultraviolet absorbing synthetic mica of the present invention has a high whiteness even though the content of trivalent iron oxide is relatively high. Absorption synthetic mica. Therefore, when mixed with plastics or the like, a smaller amount of the material than that of conventional materials exhibits an excellent ultraviolet absorption effect. When mixed with paints, synthetic mica is usually used in the form of fine powder with a thickness of 1 μm or less, but in this case as well, a relatively thin coating film thickness of 10 μm or less and sufficiently high UV Shows prevention effect and light resistance effect.

Moreover, the ultraviolet absorbing synthetic mica of the present invention is excellent in chemical resistance such as chemical resistance and water resistance, and also has the feature that it does not contain any harmful components to the human body.
Besides, it can be manufactured with high productivity at low cost,
It is extremely useful as an ultraviolet protective material used as a mixture in cosmetics, plastics, coating films, etc.

In particular, according to the ultraviolet absorbing synthetic mica of claim (2), the productivity is further improved, and the whiteness and the ultraviolet absorbing ability are further improved.

Claims (2)

[Claims] 1. The Fe content is ₂ to 18% by weight in terms of Fe ₂ O ₃ , the divalent Fe content is 0.8% by weight or less in terms of FeO, and the FeO equivalent value and Fe ₂ O _{3 are the same.} The weight ratio of the FeO converted value to the sum of the converted value is Flake ultraviolet absorbing synthetic mica characterized in that. 2. Ce to 0.5 to 13% by weight in terms of CeO _2.
The flaky ultraviolet absorbing synthetic mica according to claim 1 which is contained.