JPH0776299B2 - Method for producing polyamide composite particles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention prevents close packing of particles caused by vibration,
The present invention relates to a method for producing polyamide composite particles suitable for transportation, storage and the like.

[Conventional technology]

Spherical fine particles of polyamide are conventionally known as base particles for cosmetics.

For example, nylon 12 powder obtained by rapidly polymerizing laurolactam in the presence of an alkali metal catalyst and precipitating it into powder is a nearly spherical particle, which is used, for example, as a cosmetic material.

[Problems to be Solved by the Invention]

Polyamide spherical particles are spherical particles that have a relatively uniform particle size and are close to true spheres, so they are stored in a container for long-term storage, or when vibration is applied, they are gradually densely packed in the container and become solidified. .

This becomes remarkable especially when the polyamide spherical particles are dispersed in a liquid.

And once this state is reached, it becomes almost impossible to disperse again.

Such solidification can occur during the packing and transportation of powder, or the storage and transportation of powder dispersion.

This phenomenon is considered to be caused by the close packing of spherical particles due to vibration.

The present invention provides composite particles in which the closest packing in the method for producing spherical polyamide particles does not occur.

[Means for Solving the Problems]

That is, in the method for producing the polyamide composite particles according to the present invention, a plurality of polyamide spherical particles having an average particle diameter of 0.1 to 30 μm are attached through the polysiloxane by contacting the polyamide spherical particles with polysiloxane. It is characterized by.

Hereinafter, the present invention will be described more specifically.

The polyamide in the present invention is a polyamide having a repeating unit having 6 or more carbon atoms, such as nylon 6,
Nylon 66, Nylon 610, Nylon 611, Nylon 612, Nylon 11, Nylon 12 and copolymers of these are listed, but because of the ease of making spherical particles and the wide range of applications,
Nylon 12 is preferred.

In the case of nylon 12, for example, polyamide spherical particles can be obtained by polymerizing laurolactam using liquid paraffin as a solvent with an alkali metal or a phosphorus-based initiator, and dispersing this in a non-solvent such as alcohol. .

The average particle diameter of the polyamide spherical particles needs to be 0.1 to 30 μm, and preferably 3 to 20 μm. The average particle size is 0.
If it is smaller than 1 μm, the characteristics of the spherical particles cannot be exhibited, and the feeling when touched by the hand is deteriorated, and if it exceeds 30 μm, a foreign body feeling is felt.

The polysiloxane in the present invention is not particularly limited, and those commercially available as silicone oil can be used.

Polysiloxane is generally With a repeating unit of R, R'is hydrogen, an alkyl group,
It can be modified into an active one by changing it to an amino group or the like, but in the present invention, dimethylpolysiloxane which is chemically inactive and is thermally stable is preferable.

Polysiloxane has various viscosities depending on its molecular weight, and various kinds of polysiloxane are commercially available.
(25 ° C) is preferable, more preferably 1,000 to 8,000 CS
(25 ° C). This polysiloxane with a viscosity of 500 CS or less can coat the surface of each particle, but the effect of interposing each particle and adhering each particle is poor, and those with a viscosity of more than 10,000 CS are evenly distributed on the particles. Difficult to attach.

By interposing polysiloxane between polyamide spherical particles,
Examples of the method of attaching the polyamide particles to each other include a dry blending method and a wet blending method.

The dry blending method is a method of kneading polyamide particles and polysiloxane in a Henschel mixer or the like, which is effective for polysiloxane having a relatively low viscosity.

The wet blending method is a method in which polysiloxane is diluted with, for example, a fluorine-based, aromatic-based or aliphatic-based solvent, the polyamide particles are kneaded in a mixer, and then the solvent is removed. This method is effective for a polysiloxane having a relatively high viscosity.

The amount of polysiloxane used is preferably 1 to 50% by weight, more preferably 4 to 15% by weight, and particularly preferably 6 to 10% by weight, based on the polyamide particles. If it is less than 1% by weight, the effect of adhering particles is poor, and if it is more than 50% by weight, the feel of the powder is lost.

In order to obtain the composite particles of the present invention, it is preferable to perform heat treatment at 100 to 130 ° C. for 4 hours or more after the above dry blending or wet blending.

[Work]

In the present invention, the composite particles mean particles in which a plurality of particles are attached via polysiloxane, and it is considered that the particles are flocculated.

FIG. 1 is a schematic view showing a state in which the composite particles of the present invention are present in a corner of a container, and polyamide particles 1 are stuck to each other via polysiloxane 2 on the surface to form a plurality of flocs.

FIG. 2 shows a state in which the polyamide particles 1 are packed in the corner of the container in the closest packed state.

When FIG. 1 and FIG. 2 are compared, in FIG. 1 there is a lot of space (dispersion medium) and it is in a fluffy state, but in FIG. 2, particles are densely packed and it is easy to solidify.

In the composite particles of the present invention, polysiloxane is present between each particle, and this acts to prevent the closest packing of particles.

〔Example〕

Example 1 Dimethylsiloxane having a viscosity of 5,000 CS (25 ° C.) (Toray
Silicone "SH200") 8 parts by weight and average particle size 5
Micron nylon 12 particles (“SP-500” manufactured by Toray Industries, Inc.) 10
0 parts by weight was mixed with a Henschel mixer at room temperature for 5 minutes, and then dried in a vacuum dryer at 5 Torr or less and 120 ° C. for 24 hours.

An electron micrograph of the obtained composite particles is shown in FIG. From FIG. 3, polysiloxane is present between the polyamide particles,
It can be seen that each particle is flocculated.

FIG. 4 is an electron micrograph of polyamide particles for comparison.

20 parts by weight of composite particles obtained by the above method and 55% ethanol 10
0 part by weight was placed in a closed container and stirred at room temperature for 3 days.
The resulting composite particle slurry is placed in a closed container and shaken.
I gave it for 50 hours. As a result of observing the agglomerated state of the polyamide composite particles in the closed container after the vibration, the particles were found to settle, but they were easily dispersed in the liquid when the container was shaken lightly. This confirmed that close packing did not occur.

Comparative Example 1 20 parts by weight of the nylon particles of Example 1 containing no polysiloxane and 100 parts by weight of 55% ethanol were placed in a closed container, and the result of the same vibration as in Example 1 was confirmed to be the closest packing. The precipitated nylon particles were extremely strongly aggregated, and the aggregate could not be dispersed even if treated for 20 minutes in an ultrasonic cleaner.

〔The invention's effect〕

In the composite particles of the present invention, polysiloxane is present between the particles, and the particles stick to each other to form flocs.
And since polysiloxane has an appropriate viscosity,
Limit the movement of each particle.

Therefore, even if vibration is applied, the particles do not enter the gaps and do not become the closest packed state.

[Brief description of drawings]

1 and 2 are schematic views showing a state where polyamide particles are present in the corner of a container, FIG. 1 shows a state of composite particles of the present invention, and FIG. 2 shows a state of conventional polyamide particles. Show. FIG. 3 is an electron micrograph showing the particle structure of the composite particles of the present invention, and FIG. 4 is an electron micrograph showing the particle structure of conventional polyamide particles. 1 ... Polyamide particles, 2 ... Polysiloxane.

Claims (1)

[Claims] 1. Polyamide composite particles characterized in that a plurality of polyamide spherical particles having an average particle diameter of 0.1 to 30 μm are adhered through the polysiloxane by contacting the polyamide spherical particles with polysiloxane. Manufacturing method.