JPS6318932B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to N-alkyl-N' which is used as an anti-aging agent for rubber and as a stabilizer for polymerization inhibitors of unsaturated carboxylic acids and esters thereof. -Phenyl-P-phenylenediamine granulation method.

[Prior art] N-alkyl-N'-phenyl-P-phenylenediamine, which has an alkyl group with fewer carbon atoms in its molecule, generally has a low melting point, and its melt can be easily supercooled to below the melting point. It did not crystallize, and it took a long time to cool and solidify it. For example, conventionally, N-alkyl-N'-phenyl-P-
A molten phenylenediamine was passed through an excessively cooled endless belt, and those that did not crystallize easily were cooled and solidified into flakes over a long period of time.

According to this method, an extremely long endless belt, that is, a belt flaker, is required, and there is a problem in terms of space, and the productivity is also extremely low. On the other hand, the obtained flaky N-alkyl-N'-
Phenyl-P-phenylenediamine has different flake shapes, ranging from large ones to powdered ones, which makes it difficult to measure and pollute the environment due to dust, which may even harm the health of workers. Ta.

[Problems sought to be solved by the invention] The inventor of the present invention has made the flakes uniform in size, weighed them,
We were considering a method that would make packaging easier and reduce dust, but simply making the flakes the same size would require separating them into flakes of various sizes, resulting in problems with operability and
Productivity further deteriorated, and even if the size of the flakes was made uniform, the flakes were crushed later, and the environmental pollution caused by dust could not be solved.
We have been intensively studying methods to make alkyl-N'-phenyl-P-phenylenediamine into hard particles with uniform particle shape.

That is, the purpose of the present invention is to improve operability during granulation,
The object of the present invention is to provide a method for granulating N-alkyl-N'-phenyl-P-phenylenediamine, which has good productivity, produces hard, uniform particles, is easy to measure, and does not cause dust.

[Means for Solving the Problems] The gist of the present invention is, firstly, to provide a melt of N-alkyl-N'-phenyl-P-phenylenediamine that is solid at room temperature and has a melting point of 80°C or less. is stirred in a supercooled state to precipitate crystals, and while the melt containing the precipitated crystals is in a fluid state, the temperature is maintained at a temperature below the melting point of N-alkyl-N'-phenyl-P-phenylenediamine. A second method for granulating N-alkyl-N'-phenyl-P-phenylenediamine, which comprises dropping the N-alkyl-N'-phenyl-P-phenylenediamine dropwise into a
A melt of N-alkyl-N'-phenyl-P-phenylenediamine, which is solid at room temperature and has a melting point of 80°C or less, is stirred in a supercooled state to precipitate crystals,
While the melt containing the precipitated crystals is in a fluid state, paraffin which has been heated and is in a fluid state is mixed, and then N-alkyl-N'-phenyl-P-
A method for granulating N-alkyl-N'-phenyl-P-phenylenediamine, which comprises dropping the phenylenediamine and paraffin dropwise into a coolant maintained at a temperature below the melting point of the paraffin.

To explain the present invention in detail, the N-alkyl-N'-phenyl-P-phenylenediamine used in the present invention must have a melting point of 80°C or lower and is solid at room temperature. If the melting point is higher than 80° C., the melt can be easily solidified in a short period of time by the usual method, ie, by flowing or dropping the melt onto a cooled coolant. However, the melting point is 80℃
The following materials did not solidify easily even when poured or dropped into the coolant, and because they exhibited fluidity, they could not solidify into granular shapes, but instead crystallized into flakes over a long period of time.

N-alkyl-N'-phenyl-P-phenylenediamines having a melting point of 80 DEG C. or less usually have an alkyl group having 3 to 8 carbon atoms, including branched chains. For example, N-secondary heptyl such as N-(1,4-dimethylpentyl)-N'-phenyl-P-phenylenediamine, N-(1-methylhexyl)-N'-phenyl-P-phenylenediamine, etc. -N'-phenyl-P-phenylenediamine,
Secondary hexyl-N' such as N-(1,3-dimethylbutyl)-N'-phenyl-P-phenylenediamine, N-(1-methylpentyl)-N'-phenyl-P-phenylenediamine, etc. -Phenyl-P-phenylenediamine, N-isopropyl-N'-phenyl-P-phenylenediamine, and the like. Of course, the alkyl group may be a primary alkyl group. Moreover, these may be used in combination. However, it is better not to mix materials with relatively low melting points.

The process according to the invention comprises in particular N-(1,4-dimethylpentyl)-N'-phenyl-P-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-P-phenylenediamine and Suitable for granulating N-isopropyl-N'-phenyl-P-phenylenediamine, etc., and most suitable for N-(1,3-dimethylbutyl)-N'-phenyl-P-phenylenediamine. By the way, N-(1,4-
The melting point of dimethylpentyl)-N'-phenyl-P-phenylenediamine is 32-34℃, N-(1,3
-Dimethylbutyl)-N'-phenyl-P-phenylenediamine has a melting point of 44 to 49°C, and N-isopropyl-N'-phenyl-P-phenylenediamine has a melting point of 72 to 76°C. The above-mentioned materials also exhibit melting points that are approximately the same as those of structurally similar materials.

In the method of the present invention, paraffin may be added during the granulation process of N-alkyl-N'-phenyl-P-phenylenediamine and then granulated. As the paraffin, it is desirable to use paraffin having a melting point of about 35 to 90°C, particularly about 45 to 80°C, such as solid paraffin, paraffin wax, microcrystalline wax, etc. Paraffin is 20 to 80% by weight, preferably 30 to 60% by weight based on the total amount with N-alkyl-N'-phenyl-P-phenylenediamine.
The content is preferably within a range of % by weight.

To carry out the method of the present invention, first, N-alkyl-N'-phenyl-P-phenylenediamine is added to the melt during the production of N-alkyl-N'-phenyl-P-phenylenediamine, or to N-alkyl-N'-phenyl-P-phenylenediamine in the form of flakes or powder. The temperature of nylene diamine is raised to a temperature above its melting point to completely melt it, and then the molten liquid is supercooled to a temperature 5 to 50°C lower than its melting point using a refrigerant. Stirring in a supercooled state (applying shearing force) may be carried out while stirring, or may be performed after reaching a supercooled state. For example, if the state is supercooled while stirring, N-alkyl-N'-phenyl-
Although it depends on the type of P-phenylenediamine, fine crystals gradually or quickly precipitate, resulting in a state in which the crystals are mixed in the melt.

The supercooling temperature is appropriately determined depending on the type of N-alkyl-N'-phenyl-P-phenylenediamine. If the supercooled state is maintained for a long period of time, the entire melt will solidify, so once an appropriate amount of crystals have precipitated, it is desirable to heat it again at a temperature above the melting point while stirring.

The temperature above the melting point is sufficient if the temperature of the heating medium is above the melting point, and it is preferable that the temperature is not extremely high. For example, it is preferably above the melting point and within 20°C, preferably within 10°C, especially within 5°C, and in long-term operations, the temperature of the melt itself often reaches that temperature. Even when the temperature increases, the precipitated crystals do not melt easily and the melt containing the crystals remains in a fluid state.

When the method of the present invention is used, the molten liquid in which the N-alkyl-N'-phenyl-P-phenylenediamine crystals are precipitated is cooled and maintained at a low temperature below the melting point while it is in a fluid state. coolant, e.g. onto an endless belt or dripping into water. The temperature of the coolant should be as low as possible, i.e. N-alkyl-N'-phenyl-P
- The larger the difference between the melting point of phenylenediamine and the temperature of the coolant, the better. It is desirable that the content of fine crystals in the melt in a fluidized state to be dripped be high, but if it is too high, there is a risk of clogging the nozzle of the dripping device, etc., so it should be kept at 80% by weight or less, preferably 40~
Suitably, it is added dropwise at a crystal concentration in the range of 70% by weight.

When using the method of the present invention, while the melt of N-alkyl-N'-phenyl-P-phenylenediamine is in a fluid state, paraffin that has been further heated and is in a fluid state may be mixed therein. can. N-alkyl-N'-phenyl-P-phenylenediamine containing paraffin can be granulated extremely easily by dropping a homogeneous mixture of the two in a fluidized state onto a coolant. N-alkyl-N′- containing paraffin
Dropping conditions for dropping the melt of phenyl-P-phenylenediamine can be appropriately selected depending on the physical properties and content of paraffin, which can be determined by a simple test. Furthermore, the temperature of the coolant and the crystal content in the melt can be easily determined by similar tests.

The molten liquid containing crystals dropped onto the coolant solidifies immediately or rapidly, and has a circular cross-sectional shape.

In the granulation method of the present invention, N-alkyl-
While the melt containing crystals of N'-phenyl-P-phenylenediamine is in a fluid state, additives such as stearic acid and zinc white can be added as appropriate in addition to paraffin.

[Effects of the Invention] The present invention has particularly remarkable effects as described below, and its industrial utility value is extremely large.

(1) According to the method of the present invention, N-alkyl-N'-
By precipitating its fine crystals in the phenyl-P-phenylenediamine melt, it can be easily dropped from a dropping nozzle, etc., and the dropped material can be solidified immediately or quickly. As a result, it is possible to obtain products with excellent operability and productivity, as well as uniform, extremely hard grains with uniform shapes.The obtained products do not easily shatter, are easy to measure, and are environmentally hygienic with no dust. It is also very convenient in terms of occupational health.

(2) When using the method of the present invention, the size of the granular product can be easily adjusted to an appropriate size by selecting the dropping nozzle, for example, 2 mm to 50 mm, thus meeting the needs of various customers. Can be done.

(3) When using the method of the present invention, by adding a sieving step after the granulation step, the granular product can be easily sieved.

(4) When using the method of the present invention, the molten liquid containing crystals dropped onto the coolant is immediately solidified by the coolant. Therefore, when an endless belt is used as a coolant, the endless belt can be shortened, so there is an advantage that less space is required. Furthermore, when water is used as a coolant, there is an advantage that the amount of water used can be small.

(5) According to the method of the present invention, N-alkyl-N'-
Paraffin is mixed in the granulation process of phenyl-P-phenylenediamine, and N-alkyl-N'-
Since it has a uniform composition with phenyl-P-phenylenediamine, when it is used as an anti-aging agent for rubber, for example, the step of mixing paraffin at the rubber manufacturer can be omitted.

[Examples] The method of the present invention will be explained in detail below using Examples, but the present invention is not limited to the following Examples unless the gist of the invention is exceeded.

Example 1, Comparative Example 1 N-(1,3-dimethylbutyl)-N'-phenyl-P-phenylenediamine (melting point 44-49°C) in the form of flakes was heated to 60°C to completely dissolve it. Melted. This was gradually cooled with a refrigerant while stirring to a temperature below the melting point of the phenylenediamine. At 44°C, no microcrystals were observed, and when cooled to 35°C, almost half of it crystallized, forming a molten liquid containing crystals and becoming fluid.

When this melt was dropped with a pipette onto a stainless steel plate cooled to about 15°C, it immediately solidified into a hemispherical pellet with a diameter of 4.7 mm and a height of 3.5 mm.

For comparison, when a melt at 60°C and 44°C in which no fine crystals were observed was dropped in the same manner onto a stainless steel plate cooled to approximately 5°C, the result was 60°C.
The melt at ℃ flowed in a plate shape, did not form droplets, and could not be granulated. The 40°C melt turned into droplets, but they did not solidify immediately, and it took a day and night for them to solidify.

Example 2 Large amount of N-(1,3-dimethylbutyl)-N'-
A 60°C melt of phenyl-P-phenylenediamine was slowly cooled with a refrigerant while stirring, and the melt temperature was lowered to 32°C, resulting in a melt containing a large amount of precipitated fine crystals. This molten liquid containing fine crystals is continuously heated over a long period of time on an operating stainless steel endless belt maintained at a temperature of approximately 10°C while stirring and heating hot water at 50 to 51°C. dripped. The dropped molten liquid immediately solidified and became a product consisting of small semicircular particles.
The temperature of the melt containing the precipitated fine crystals was 50°C.

Example 3 The same amount of paraffin wax in a fluid state with a melting point of about 50°C was added to the crystal-containing melt cooled to 35°C used in Example 1, and the two were mixed uniformly. It was dropped onto a stainless steel plate cooled to ℃. The dropped liquid quickly solidifies and has a diameter of 7 mm.
It turned into semi-spherical pellets.

Example 4 N-isopropyl-N'-phenyl-P-phenylenediamine (melting point 72-76°C) was completely melted at a temperature of 85°C, and the melt was supercooled to 60°C with stirring. A large amount of fine crystals precipitated in this melt, resulting in a melt containing fine crystals. When this melt containing microcrystals was dropped onto an endless belt maintained at about 5°C, it immediately solidified and the diameter was about 5°C.
mm hemispherical pellets.

Claims (1)

[Claims] 1. A melt of N-alkyl-N'-phenyl-P-phenylenediamine, which is solid at room temperature and has a melting point of 80°C or less, is stirred in a supercooled state to precipitate crystals. While the melt containing the precipitated crystals is in a fluid state, N-alkyl-N'-phenyl-P-
1. A method for granulating N-alkyl-N'-phenyl-P-phenylenediamine, which comprises dropping N-alkyl-N'-phenyl-P-phenylenediamine into a coolant maintained at a temperature below the melting point of phenylenediamine. 2 N-alkyl-N'-phenyl-P-phenylenediamine according to claim 1, wherein the alkyl group has 3 to 8 carbon atoms.
A method for granulating N'-phenyl-P-phenylenediamine. 3 N-alkyl-N'-phenyl-P-phenylenediamine is N-secondary hexyl-N'-phenyl-P-phenylenediamine or N-secondary hexyl-N'-phenyl-P-phenylenediamine
A method for granulating N-alkyl-N'-phenyl-P-phenylenediamine according to claim 1, which is heptyl-N'-phenyl-P-phenylenediamine. 4 N-alkyl-N'-phenyl-P-phenylenediamine is N-isopropyl-N'-phenyl-P-phenylenediamine or N-(1,3
A method for granulating N-alkyl-N'-phenyl-P-phenylenediamine according to claim 1, which is N-dimethylbutyl)-N'-phenyl-P-phenylenediamine. 5 A melt of N-alkyl-N'-phenyl-P-phenylenediamine that is solid at room temperature and has a melting point of 80°C or less is stirred in a supercooled state to precipitate crystals, and a melt containing the precipitated crystals is prepared. While the paraffin is in a fluidized state, the heated and fluidized paraffin is mixed and then dropped into a coolant maintained at a temperature below the melting point of the N-alkyl-N'-phenyl-P-phenylenediamine and the paraffin. N-alkyl-N'-phenyl-P, characterized in that
- A method for granulating phenylenediamine. 6 N-alkyl-N'-phenyl-P-phenylenediamine according to claim 5, wherein the alkyl group has 3 to 8 carbon atoms.
A method for granulating N'-phenyl-P-phenylenediamine.