JPH07116105B2 - Independent particle α-crystal tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxymethyl] methane and method for producing the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to tetrakis [3- (3,5-di-t-butyl-4) having an α-crystal crystal structure useful as an antioxidant for polyolefins and the like. -Hydroxyphenyl) propionyloxymethyl] methane (hereinafter, sometimes referred to as compound-A), a new independent particle crystal, more specifically, a substantially cubic or rectangular parallelepiped having the α-crystal structure of compound-A, and those thereof. The present invention relates to an independent particle crystal composed of an aggregate and a method for producing the same.

[Conventional technology]

The currently commercially available compound-A products are fine powders having a low bulk specific gravity, poor fluidity, and easy to scatter during handling, so that they are inferior in so-called powder characteristics, which are important problems in workability, meterability and environmental hygiene. And the improvement is desired.

Compound-A has a property called polymorphism in crystallography and has the same chemical structural formula, but there are various stable or metastable crystal forms, and α-, β-, and γ-crystals have been known so far. , Several crystal forms defined by δ crystal and the like are known, and the above-mentioned commercially available product has a crystal structure of β crystal. There is a close relationship between each crystal form and the purity and powder characteristics of Compound-A, and the desired crystal form has been obtained by various methods.

Conventionally, proposals have been made to improve the drawbacks of commercially available products by obtaining Compound-A having a specific crystal form, or by obtaining Compound-A by combining a specific crystal form and a special particle form. . For example, (1) Japanese Patent Publication 60-130
No. 18, 60-13017, δ is a metastable crystal form.
To improve the powder characteristics, which is a drawback of the α crystal and the commercially available β crystal, and (2) JP-A-62-258343 discloses that the crystal form is a metastable β crystal. It is disclosed that the drawbacks of the commercial product are improved by recrystallizing under the same conditions as the commercial product, but under specific conditions to obtain crystals expressed as independent grain crystals.

On the other hand, α crystal belongs to the stable crystal form,
As disclosed in JP-A No. 42-19083 and JP-A No. 60-156645, it can be obtained by recrystallization from n-heptane, n-hexane, methanol, etc. At present, the value as an inferior product is small.

[Problems to be Solved by the Invention]

As described above, the conventional method is a compound-
In order to obtain A, there has been proposed a method of avoiding an α crystal, which is inferior in purity and powder characteristics, and forming an unstable δ crystal as a crystal structure or an independent particle β crystal. Neither can be said to be an economical method, for example, it is necessary to increase the amount of impurities or to make impurities exist in large amounts. That is, in the methods of Japanese Examined Patent Publication Nos. 60-13017 and 60-13018, the formula (1) is used in the transesterification reaction (Wherein each of R ¹ and R ² represents an alkyl group having 1 to 6 carbon atoms), it is necessary to add a dicarboxylic acid ester, and a molecular adduct of compound-A with isopropanol. Since isolation is required, the number of steps increases, etc.
Not an economical method. Further, in JP-A-62-258343, before the recrystallization purification, methyl (ethyl) or ethyl 3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate and a compound of formula (2) are used. It is necessary to add a large amount of the tris-substituted product, which is an unfinished reaction intermediate represented by (the content of the target compound-A becomes too high at the end of the reaction as described in the same specification). In this case, the raw material or the tris-substituted product (2) must be mixed), and the purity of the obtained product tends to be low, and at the same time, the recrystallization yield is poor, which is not an economical method.

The present invention relates to an α-crystal compound-A having a high purity, excellent powder characteristics, and belonging to a stable crystal structure, that is, an independent particle-shaped α-crystal compound-A consisting essentially of a cubic or rectangular parallelepiped and an aggregate thereof. It is an object to provide a manufacturing method thereof.

[Means for Solving the Problems]

The inventors of the present invention have conducted extensive studies on the crystal structure of Compound-A, particularly the α crystal, and surprisingly found that it has a particle shape different from that of the conventionally known α crystal, that is, powder characteristics are good. Moreover, the present invention has been completed by finding a novel α-crystal compound-A having a particle shape.

DISCLOSURE OF THE INVENTION The present invention provides tetrakis [3- (3,5-di-t-t-obtained by transesterifying methyl 3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate with pentaerythritol. Butyl-4-hydroxyphenyl) propionyloxymethyl] methane or a commercially available product thereof, which is substantially obtained by recrystallization using a mixed solvent of an aliphatic saturated hydrocarbon solvent having 8 to 10 carbon atoms and a small amount of methanol. Independent particle α-crystal tetrakis [3- (3) consisting of cubes or cuboids and their aggregates
(3,5-di-t-butyl-4-hydroxyphenyl) propionyloxymethyl] methane.

Specific examples of the aliphatic saturated hydrocarbon solvent having 8 to 10 carbon atoms used in the present invention include Isopar (trade name of Exxon chemicals), Shellsol (trade name of shell chemicals), IP Solvent (trade name of Idemitsu Petrochemicals). And so on. The amount of methanol added may be 1 to 4% by weight based on the solvent. The content of compound-A before crystallization is about 85 to 98%. Further, the crystallization temperature is in the range of 70 ° C to 20 ° C.

In the independent particle-shaped α-crystal compound-A of the present invention, the proportion of crystal grains having a crystal grain diameter of 0.1 mm or less is 5% by weight or less, and more preferably the proportion of crystal grains having a crystal grain diameter of 1 mm or more. 1% by weight, the proportion of crystal particles of 0.1 to 1 mm is 94% by weight or more, and the proportion of crystal particles of smaller than 0.1 mm is 5% by weight or less, and the particle size distribution is uniform.

[Action]

The compound-A obtained by the present invention is represented by X shown in FIG.
Since it was determined to be the crystal structure of the α crystal from the X-ray (Cu-Kα) diffraction spectrum and the melting point of 122 to 124 ° C., as shown in the micrograph of FIG. It can be seen that the crystal form is a particle form containing almost no fine powder and is clearly distinguished from the α crystal obtained by the conventional method shown in the micrograph of FIG.

Further, unlike the conventionally known α-crystal, the α-crystal compound-A obtained according to the present invention is essentially an independent particle crystal, so that it can be easily purified to high purity by recrystallization, and has a particle size distribution. Is uniform and has a narrow width, has a large bulk specific gravity, and is not easily crushed during drying and transportation, and has the great feature that it is excellent in so-called powder characteristics, and it is possible to improve work efficiency and work environment. That is very advantageous. Thus, the α-crystal compound-A of the present invention is
It has high purity and excellent powder characteristics not found in conventionally known α crystals, and is easy to manufacture.

[Examples] Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited thereto.

Reference Example Commercially available tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxymethyl] methane (The shape of this product is a fine powder as shown in the micrograph in Fig. 7. And having a melting point of 112 to 114 ° C. and an X-ray diffraction spectrum shown in FIG. 2 and having a β-crystal structure. 150 g and Isopar E180 g (commercially available from Exxon Chemicals and saturated with 8-10 carbon atoms (Hydrocarbon solvent) was added to a 500 ml four-necked flask and heated to 95 ° C. to completely dissolve it. Gradually cool with stirring and add a small amount of α at 70 ° C.
The crystals were added as seed crystals, and most of the crystals were precipitated by continuing stirring at 60 to 50 ° C. for 4 hours. Further, it was cooled to 30 ° C. to complete crystallization. The resulting slurry was filtered by suction filtration and then dried to obtain 146 g of white crystals with good fluidity. It was confirmed from the melting point (122 to 124 ° C.) and the X-ray diffraction spectrum shown in FIG. 1 that this crystal was an α crystal.

The properties of the obtained crystal are α obtained by a commercial product and a conventional method.
The results are summarized in Table 1 in comparison with the crystals.

Example 1 In the method of Reference Example 1, as a result of performing exactly the same operation except that 3.7 g of methanol was newly added at the time of dissolution,
145 g of white crystals with good flowability were obtained. This crystal has a melting point (12
2 to 124 ° C.) and X-ray diffraction spectrum confirmed that the crystals were α crystals.

Example 2 3- (3,5-di-t-butyl-4) was added to a 4-necked flask equipped with a stirrer, a reflux condenser, a thermometer and a pressure reducing valve.
-Hydroxyphenyl) methyl propionate 479.5g, pentaerythritol 54.5g and dibutyltin oxide
0.25 g was added and the reaction was carried out at 195 ° C./atmospheric pressure for 2 hours, and by-product methanol was distilled off. The reaction was continued for 2 hours under a reduced pressure of 195 ° C./40 mmHg, and further for 12 hours under a reduced pressure of 195 ° C./2-5 mmHg, and the by-product methanol was distilled off to complete the reaction. The weight of the reaction product after returning to atmospheric pressure with nitrogen was 483 g, and as a result of HPLC analysis, it contained 89% of the target product.

150 g of this reaction, 170 g of Isopar E and 6.2 of methanol
After adding g to a 500 ml 4-neck flask and heating to 85 ° C to make a uniform solution, gradually cool with stirring and add a small amount of α crystal seed crystals at 55 ° C and crystallize at 50-45 ° C for 8 hours. Was analyzed. Then, it was further cooled to 25 ° C. to complete crystallization and the crystals were collected by filtration.
The obtained crystals were washed with 100 mg of cold Isopar E and then dried to obtain 126 g of white crystals with good fluidity. It was confirmed from the melting point (122 to 124 ° C.) and the X-ray diffraction spectrum shown in FIG. 3 that this crystal was an α crystal.

Comparative Example 1 Using 150 g of the reaction product obtained in Example 2, Isopar E
Instead of 170 g, 170 g of methanol used in Example 1 of JP-A-60-156645 was used, heated to 68 ° C. to form a uniform solution, and then crystallized by the method described in Example 3. did.
The obtained crystals were washed with 100 ml of cold methanol and then dried to obtain 120 g of white powder. This crystal has a melting point (122-124
C.) and the X-ray diffraction spectrum shown in FIG.

Comparative Example 2 In the method of Comparative Example 1, instead of methanol,
The same operation was performed except that the n-heptane used in Example 2 of 42-18617 was used to obtain 118 g of a slightly yellow powder.
It was confirmed from the melting point and X-ray diffraction spectrum that this powder was an α crystal.

Comparative Example 3 In the method of Comparative Example 1, instead of methanol,
The same operation was performed except that n-hexane used in Example 1 of 42-19083 was used and the crystallization temperature was 40 ° C., and 125 g of a slightly yellow powder was obtained. It was confirmed from the melting point and X-ray diffraction spectrum that this powder was an α crystal.

Test Example 1 Table 1 shows the crystal properties of Reference Example, Examples 1 and 2, Comparative Examples 1 to 3 and a commercial product. The bulk specific gravity and the angle of repose were measured with a powder tester (manufactured by Hosokawa Micron). The falling speed is the falling speed from the stainless steel hopper shown in FIG. 8, and the smaller the value, the better the fluidity. The commercial product is a product of Ciba-Geigy.

Test Example 2 The mechanical strength of the crystal particles of the compound-A obtained in Example 2 was tested by a shaking stirring method. A 100 g sample was placed in a 1000 ml flask and shaken for 7 hours, and the results of particle size distribution before and after the test are shown in Table 2. Since the particle size distribution before and after the test hardly changes, it can be seen that the mechanical strength of the crystal particles is high.

[Brief description of drawings]

1 is an X-ray diffraction spectrum of the compound of the present invention obtained in Example 1; FIG. 2 is an X-ray diffraction spectrum of a commercial product used in Example 1; FIG. 3 is a compound of the present invention obtained in Example 3. FIG. 4 is an X-ray diffraction spectrum of the compound obtained in Comparative Example 1; FIG. 5 is a micrograph of the structure of a crystal of the independent particle α crystal obtained by the present invention; Fig. 7 is a photomicrograph of the crystal structure of α crystal obtained by the method; Fig. 7 is a photomicrograph of the crystal structure of a commercial product; and Fig. 8 is the hopper (1 is a cylindrical part, 2 is a cone) used for measuring the fall time. Part, 3 represents the sample outlet).

Claims (8)

[Claims] 1. Tetrakis [3- (3,5-di-t-butyl-4-), which is an independent particle crystal having an α crystal structure and substantially consisting of a cubic or rectangular parallelepiped and an aggregate thereof. Hydroxyphenyl) propionyloxymethyl] methane. 2. The compound according to claim 1, wherein the proportion of crystal particles having a crystal particle diameter of 0.1 mm or less is 5% by weight or less. 3. The proportion of crystal grains having a crystal grain size of more than 1 mm is 1% by weight or less, and the proportion of crystal grains of 0.1 to 1 mm is
The compound according to claim 1, wherein the proportion of crystal particles of 94% by weight or more and smaller than 0.1 mm is 5% by weight or less. 4. The compound according to claim 1, which is obtained by crushing the crystal. 5. A tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxymethyl] methane is mixed with an aliphatic saturated hydrocarbon solvent having 8 to 10 carbon atoms and a small amount of methanol. Α-crystal independent particle-like tetrakis [3] consisting essentially of a cubic or rectangular parallelepiped and their aggregates characterized by crystallization using a mixed solvent
-(3,5-di-t-butyl-4-hydroxyphenyl)
Method for producing propionyloxymethyl] methane. 6. The amount of methanol added is 8 to 10 carbon atoms.
The method according to claim 5, wherein the content is 1 to 4% by weight with respect to the saturated aliphatic hydrocarbon. 7. Tetrakis [3- (3,5-di-t before crystallization.
The method according to claim 5, wherein the content of -butyl-4-hydroxyphenyl) propionyloxymethyl] methane is 85 to 98%. 8. The method according to claim 5, wherein the crystallization temperature is in the range of 70 to 20 ° C.