JPH02286657A - Solventless crystallization of polyalkylpiperidylester compound of polyfunctional carboxylic acid and granulation of same compound - Google Patents

Abstract

PURPOSE:To make possible of solventless crystallization of the subject compound useful as light stabilizer by growing crystal from melt of polyalkylpiperidylester compound of multifunctional carboxylic acid having specific melting point with specific method. CONSTITUTION:A melt of polyalkyl piperidylester compound of polyfunctional carboxylic acid having 50-150 deg.C melting point [e.g. bis(2,2,6,6-tetramethyl-4- piperidyl)succinate] is subjected to crystal growing in extruder, kneader or closed mixer to perform solventless crystallization of polyalkylpiperidylester compound of polyfunctional carboxylic acid. Crystallized substance obtained by the above method is extruded as strand like or belt-like through direct die or extruder having die and immediately after the extrusion, subjected to breaking and rough crushing to readily afford granules having uniform shape.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method for solvent-free crystallization of a polyalkylpiperidyl ester compound useful as a light stabilizer for synthetic resins, etc. The present invention relates to a method for solvent-free crystallization of a polyalkylpiperidyl ester compound of a polyhydric carboxylic acid and a method for granulating the crystallized product.

[Prior art and its problems]

2.2,6i 6-tetramethyl- of polyhydric carboxylic acid
Polyalkylpiperidyl ester compounds of polycarboxylic acids represented by 4-piperidyl esters are known as hindered amine light stabilizers, and have a completely different mechanism from conventional UV absorbers such as benzophenone compounds and benzotriazole compounds. It has the characteristic of stabilizing synthetic resins, and its usage has been rapidly increasing in recent years.

These compounds include polyvalent carboxylic acids, their acid halides, or their lower alkyl esters and polyalkyl-
It is well known that it can be synthesized by reacting a 4-hydroxypiperidine compound in the presence or absence of a catalyst, and after the reaction, it can be produced as a fine powder by crystallizing or recrystallizing it using an organic solvent. has been done.

However, when crystallizing using these organic solvents, a large amount of organic solvent is required, and furthermore, a solid-liquid separation process and a drying process are required, which not only makes the process complicated but also Occupational hygiene problems such as generation of solvent vapor or dust have arisen.

For this reason, various studies are underway to crystallize products without using organic solvents, not only for industrial and economic reasons but also for environmental reasons.

Examples include a method in which a molten reaction product is solidified using a flaker, and a method in which a molten reaction product is solidified by 'f@, i in a spray tower. However, these methods have the disadvantage that they solidify and adhere to the surfaces of metals and resins such as cooling healds, rolls, and inner walls of the tower, forming large lumps or containing fine powder. Furthermore, in these methods, the molten product is rapidly cooled, causing a partially amorphous state, resulting in the contamination of low-melting point materials, which also has the disadvantage of causing solidification, secondary aggregation, etc. of the product.

In addition, studies are being conducted to prevent the generation of dust by granulating fine powder products.

However, such a method of first producing a finely powdered product and then granulating it is not only complicated, but also has various drawbacks, and is not practically satisfactory. That is, a dry granulation method that does not use a binder has the disadvantage of uneven particle size, and a method of granulation that uses an organic substance as a binder has the disadvantage that the binder is mixed into the product as an impurity. Ta.

[Means to solve the problem]

In view of the above-mentioned current situation, the present inventors have aimed to obtain a granular product that can be directly and completely converted into a crystalline state without using an environmentally problematic crystallization solvent, and that is easy to work with and does not generate dust. As a result of extensive research to find a method suitable for large-scale production, we have developed a method in which crystals are grown in a melt of a polyalkylpiperidyl ester compound of a polyhydric carboxylic acid in an extruder, kneader, or internal mixer. The molten material can be completely crystallized without using a solvent, and the crystallized material can be easily granulated by extruding it into a strand or band shape through a die and then crushing or coarsely crushing it. I found out what I can do.

That is, the present invention is a polyhydric compound characterized by growing crystals of a polyalkylpiperidyl ester compound of a polyhydric carboxylic acid having a melting point of 50°C to 150°C in an extruder, a kneader, or an internal mixer. A method for solvent-free crystallization of a polyalkylpiperidyl ester compound of a polyvalent carboxylic acid, and the crystallized product obtained by the above method is directly extruded as a strand or band through a die or an extruder equipped with a die, and then crushed or coarsely crushed. characterized by
The present invention provides a method for granulating a polyalkylpiperidyl ester compound of a polyhydric carboxylic acid.

Hereinafter, the present invention having the above-mentioned summary will be explained in more detail.

As the extruder, kneader, and internal mixer used in the present invention, conventional equipment can be used, and it is particularly preferable to use a single-screw or twin-screw extruder or a planetary roller extruder.

When using an extruder or an internal mixer, it is preferable to carry out the process continuously from the viewpoint of productivity, but sufficient effects can also be achieved by a batch process. Moreover, when using a kneader, it is preferable to carry out the process in a batch manner.

The polyalkylpiperidyl ester compound of polycarboxylic acid to which the method of the present invention can be applied has a melting point of 50°C to 1°C.
Preferably, the temperature is 50°C. Compounds with melting points lower than 50°C are difficult to crystallize, requiring long residence times and large amounts of energy to cool the equipment, and compounds with melting points higher than 150°C are difficult to crystallize. Since the material solidifies rapidly, it is expected that not only will amorphous parts be easily mixed in, but also that the torque within the device will increase, causing problems in the operation of the device.

Examples of polyalkylpiperidyl ester compounds of polyhydric carboxylic acids having a melting point of 50°C to 150°C include bis(2,2,6,6-tetramethyl-4-piperidyl)succinate, bis(2,2°6 .6-tetramethyl-4
-piperidyl)adipate, bis(2,2,6,6-tetramethyl-4piperidyl)sebacate, tris(2,
2,6゜6-tetramethyl-4-piperidyl)nitrilotriacetate, tris(2,2,6,6-tetramethyl-4-piperidyl)butanetricarboxylate, tris(2,2,6,6-tetramethyl 4-piperidyl)
citrate, tetrakis(2゜2.6.6-tetramethyl-4-piperidyl)butanetetracarboxylate,
Tetrakis (1゜2.2,6.6-bentamethyl-4-
piperidyl)butanetetracarboxylate, 3,9-
Bis(1,1-dimethyl-2-(tris(1,2,2°6.6-bentamethyl-4-piperidyloxycarbonyl)butylcarboxyethyl)-2,4°8.10-tetraoxaspiro(5,5 ) Polyalkylpiperidyl ester compounds of di- to tetravalent polyhydric carboxylic acids such as undecane.

In the method of the present invention, these polyalkylpiperidyl ester compounds of polyhydric carboxylic acids are supplied in a molten state to an extruder, kneader or internal mixer, and treated at a temperature at or slightly lower than the melting point of the melt. It is preferable to cool the device so that the temperature of the contents falls within this range. If the temperature of the contents is higher than the melting point, no crystals will be formed, and if the temperature of the contents is significantly lower than the melting point, the contents will solidify rapidly, so there is a risk that amorphous parts will be mixed in. Therefore, it is preferable to adjust the temperature at which crystals are formed to be within a range of from the melting point to about 5°C lower than the melting point. For example, when using an extruder, the temperature at the exit should be within this temperature range. It is preferable to adjust to

In addition, in the method of the present invention, crystallization proceeds rapidly without adding seed crystals, so there is little need to add seed crystals;
Seed crystals can also be added if more rapid and complete crystallization is desired.

Furthermore, although the processing time (residence time in the apparatus) is not particularly limited, the method of the present invention completes crystallization in an extremely short time, so generally 30 minutes or less is sufficient, and the conditions must be set appropriately. In some cases, it may take less than 10 minutes.

The product obtained by the method of the present invention exhibits the same crystal form as when crystallized using a solvent, and can be obtained in the form of a strand or band by extruding it through a die. By doing so, it is possible to easily obtain a product as granules with a uniform shape.

〔Example〕

The present invention will be explained in more detail in the following examples, but the present invention is not limited to the following examples.

Example 1 A melt of bis(2',2,6.6-tetramethyl-4-piperidyl)sebacate was transferred from a storage container at a temperature of 100 to 105°C at a rate of 20 kg/hour and rotated at a shaft rotation rate of 12 Orr.
pm twin screw extruder (with die).

The melt in the extruder is cooled with water to a temperature of 80-85°C, and after an average residence time of 7 minutes, the product is extruded into a soft strand. This was air-cooled, coarsely crushed, and then classified to obtain a uniform granular product.

The melting point of the product was 84°C, which was in good agreement with the melting point of the recrystallized product from n-heptane, 84°C.

The results of X-ray (Cu-α) diffraction analysis of the product were in good agreement with the recrystallized product, and it was confirmed that the product had the same crystal form as the recrystallized product.

Table 1 below shows the diffraction results of the crystallized products and recrystallized products of the present invention as diffraction angles (2θ:°) and relative intensity as %.

Table Example 2 A melt of bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate was heated at 110 to 120°C with axial rotation of 9
The mixture was fed to a twin-screw kneader at 0 rpm at a rate of 50 kg/hour. The contents in the kneader were cooled with water so that the temperature thereof was 80 to 82°C, and after an average residence time of 5 minutes, the contents were fed into an attached extruder.

The crystallized product is extruded into strands from an attached twin-screw L/D=8 die-equipped extruder, crushed while hot, air-cooled, and classified to produce a uniform granular product. I got it.

The melting point of the product is 84°C, and the X-ray (C
The results of the u- to α) diffraction analysis were in good agreement with the recrystallized product, and it was confirmed that the product had the same crystal form as the recrystallized product.

Example 3 A uniform granular crystallized product was obtained in the same manner as in Example 2, except that 2% by weight of bis(2,2,6,6tetramethyl-4-piperidyl)sebacate crystals were added as seed crystals. Ta.

Example 4 Same as Example 2 except that the extrusion die was changed to a strip shape,
A homogeneous granular crystallized product was obtained.

Comparative Example A melt of bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate was fed at 100 to 105°C to a flaker with a cooling belt temperature of 20°C to obtain an amorphous solidified product. .

The melting point of the obtained individualized products is 55°C to 65°C, and
As a result of X-ray diffraction analysis, 22 to 11 people and 8 to 4.2
It was confirmed that there was a halo pattern among humans and that it was a typical amorphous product.

〔Effect of the invention〕

Conventionally, polyalkylpiperidyl ester compounds of polyhydric carboxylic acids have been produced as crystalline powders by crystallizing or recrystallizing them using a large amount of organic solvents, and then granulated into granular products. but,
By the method of the present invention, it is possible to obtain granules that can be directly and completely converted into a crystalline state through an extremely simple operation without using environmentally problematic crystallization solvents, and that are dust-free and easy to work with. be able to.

Claims (4)

[Claims] (1) Polyvalent carboxylic acid, which is characterized by growing crystals of a polyalkylpiperidyl ester compound of polyvalent carboxylic acid having a melting point of 50°C to 150°C in an extruder, kneader, or internal mixer. A method for solvent-free crystallization of a polyalkylpiperidyl ester compound of an acid. (2) The method according to claim (1), wherein the polyalkylpiperidyl ester compound of a polyvalent carboxylic acid is 2,2,6,6-tetramethyl-4-piperidyl ester of a polyvalent carboxylic acid. (3) The polyalkylpiperidyl ester compound of polyhydric carboxylic acid is bis(2,2,6,6-tetramethyl-4-
Claim No. (1) which is piperidyl) sebacate
and the method described in paragraph (2). (4) A melt of a polyalkylpiperidyl ester compound of polyhydric carboxylic acid having a melting point of 50°C to 150°C is grown to crystals in an extruder, kneader, or internal mixer, and then directly extruded with a die or with a die. A method for granulating a polyalkylpiperidyl ester compound of a polyhydric carboxylic acid, which comprises extruding it through a machine in the form of a strand or band, and then crushing or crushing it.