JPH02191605A - Production of polymer powder - Google Patents

Abstract

PURPOSE:To obtain the subject powder in spherical shape suitable for powder coating, cosmetic, lubricant, etc., without using solvent by individually melting specific plural species of oligomers, spraying said melts with continuously mixing, cooling to obtain powder and subjecting said powder to solid phase polymerization. CONSTITUTION:At least two spiecies of oligomer or monomer, which are reactive with each other to give a mixture of solid at normal temperature and <=500cps, preferably <=100cps melt viscosity at 300 deg.C, (preferably polyamide oligomer having amines of both chain ends and polyamide oligomer having carboxylic acids of both chain ends) are individually melted and sprayed with continuously mixed, then cooled to obtain powder, thus resultant powder is subjected to solid phase polymerization to afford the aimed powder.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for producing polymer powder, and particularly to a method for producing a powder having a shape close to a sphere and made of a polymer compound capable of surface phase polymerization such as polyamide. Regarding the manufacturing method.

(Conventional Branch) Polymer spherical powders, especially polyamide spherical powders, have a wide range of uses in powder coatings, cosmetics, and lubricants.

For example, as for powder for powder coating, the closer the shape is to a sphere, the better the fluidity of the powder is, and the smoother and more flexible the coating. It is also used in cosmetics and lubricants because the spherical particles fit together well. However, since spherical powder cannot be supplied at low cost, spherical powder is used only in very expensive applications such as cosmetics, and potato-like or crushed stone-like powder is generally used.

Polymer powder is most commonly obtained by mechanically pulverizing at room temperature or low temperature, and the powder thus obtained has a crushed stone-like shape. As a special method, there is a method in which a polymer compound is dissolved in a solvent and then reprecipitated (JP-A-61-223059); however, this method uses a large amount of solvent, making the equipment large and unfavorable in terms of manufacturing cost.

In addition, there is a method of anionic polymerization by dispersing lactam in liquid paraffin (Japanese Patent Publication No. 45-29832), but it requires a great deal of cost to separate liquid paraffin from powder and residual catalyst, and it also has good physical properties. The disadvantage is that a polyamide cannot be obtained.Although a method of dissolving octum in a solvent and precipitating the polyamide while performing anionic polymerization is also being considered, it has the disadvantage of using a large amount of solvent and increasing the size of the equipment.

In addition, many methods have been proposed in which molten polymer is sprayed (melt gray), but filaments are generally produced and it is difficult to obtain spherical powder.

(Problems to be Solved by the Invention) An object of the present invention is to easily produce polymer powder with a shape close to a sphere.
The aim is to manufacture it safely and at low cost. The purpose is to provide polyamide powder with excellent physical properties in a shape close to a sphere at a low cost for various uses.

(Means for Solving the Problems) The present invention comprises two or more oligomers or monomers that react with each other, the mixture of which is solid at room temperature and whose melt viscosity at 300°C is 500 cps or less. rqA while melting separately and continuously mixing
I! B. A method for producing a polymer powder, which is characterized in that the powder is obtained by cooling and then subjected to solid phase polymerization.

The oligomer described in the present invention has a molecular weight of 100 to 1
It is a high molecular compound with a low molecular weight of approximately 0,000, and generally does not have excellent physical properties as a plastic.

Furthermore, polymer compounds with high molecular weight and excellent physical properties have a high melt viscosity and can only be obtained in the form of threads even when sprayed.

In order to obtain a powder with a shape close to a sphere, it is necessary that the melt viscosity at the time of spraying is 500 cps or less, preferably 200 cps or less, and more preferably 100 cps or less. On the other hand, due to the heat resistance of oligomers and monomers,
It is not preferable to spray at temperatures above 0° C. The sprayed oligomer or monomer mixture becomes spherical due to surface tension, so the mixture needs to remain molten in the air for some time after being sprayed. Therefore, it is effective for the purpose of the present invention to preferably prevent rapid solidification using a heated inert gas or the like.

If two or more types of oligomers or monomers that react with each other are mixed in advance, they will react with each other during preheating for melting or during transport to the spray nozzle, becoming polymerized, thickening, and forming filaments. Not only that, but a gel will form in the area where it stays, making spraying impossible. Alternatively, it may react on its own, as is the case, for example, with polyamide oligomers having an amine at one end and a carboxylic acid at the other end;
In the case of polymerized oligomers or monomers, thickening cannot be controlled and a similar phenomenon occurs.

The present invention solves the above problems by separately melting two or more mutually reactive oligomers or monomers that do not polymerize by themselves, and then continuously mixing them in a molten state. The mixing time in the present invention is preferably 1 second or less, more preferably 0.5 seconds or less. A specific example is a method in which two or more types of low-viscosity oligomers or monomers are passed through a thin static mixer at high speed.

The mixed oligomers or monomers are immediately ejected. At this time, static electricity can be applied to make the particle size of the eruption finer or to even out the particle size distribution. The sprayed droplets, which have a shape close to a sphere, are cooled and solidified by cold air such as an inert gas or water, and become a powder having a shape close to a sphere.

A polymer compound to which the present invention can be applied is one in which the oligomer or monomer does not substantially polymerize by itself, and a mixture of two or more oligomers or monomers can polymerize in a solid phase.

Specific examples include polyamide resins, epoxy resins, polyurethane resins, etc., but polyamide resins are most preferable. In other words, it is most preferable to use polyamide oligomers having amines at both ends and polyamide oligomers having carboxylic acid ends at both ends. Able to carry out inventions.

Examples of polyamide resins include nylon 6, nylon 66, nylon 610, nylon 612, nylon 11, nylon 12, copolymers thereof, and aromatic and alicyclic nylons.

In the present invention, various additives such as pigments, stabilizers, and polymerization catalysts may be added together with the oligomer or monomer.

(Effects of the present invention) The production method of the present invention does not use a solvent, and it is possible to easily obtain a polymer powder having a shape close to a sphere. Therefore, a polymer powder with good properties can be supplied at low cost, and this powder is preferably used for various applications such as powder coating, cosmetics, and lubricants.

(Example) The present invention will be explained in more detail with reference to Examples below.

Example Aminododecane D 5 kir, dodecanedioic acid 267, and 10 g of phosphoric acid were melt-polymerized at 250°C for 5 hours to give 0.5%
A nylon 12 oligomer having carboxylic acid at both terminals and having a relative viscosity of 1.20 in a metacresol solution was obtained.

On the other hand, 5 kg of aminododecane M and 135 g of hexamethylene diamine were polymerized under pressure at 250°C for 1 hour, then returned to normal pressure, and then polymerized for an additional 5 hours. A nylon 12 oligomer with terminal amine was obtained.

Immediately after connecting the inflow pipes of both oligomers to separate gear pumps and merging the pipes coming out of the gear pumps,
A static mixer with an inner diameter of 6φ and a length of 100 m5+ was installed, and an airless spray nozzle (LV nozzle manufactured by Nordson Corporation) was attached to the tip of the static mixer. All of these equipment were installed inside an oven, with the tip of the nozzle extending out from the oven, and a cooling chamber was attached to the tip of the nozzle so that water could flow along the wall.

Both oligomers were heated and melted separately to 250'C and supplied to the gear pump through separate piping, and the oven temperature was 250°C. Both oligomers were heated to 1001/ii.
The gear pump was adjusted to flow at a flow rate of n.

Water was flowed into the cooling chamber, and the solidified powder sprayed from the nozzle was taken out along with the flow of water to obtain a nearly spherical powder with a diameter of about 150 microns.

The filtered powder is placed in a stainless steel fluidized tank.
Solid phase polymerization was carried out by flowing nitrogen at 160° C. from below for 24 hours. The relative viscosity of a 0.5% metacresol solution of the obtained powder was 1.60.

When this powder was used to fluidize and coat a 3-city thick steel plate, a smooth coating was achieved.

Claims (1)

[Claims] The mixture is solid at room temperature, and 3
Two or more types of oligomers or monomers that react with each other and have a melt viscosity of 500 cps or less at 00°C are separately melted, sprayed while continuously mixing, and cooled to obtain a powder. A method for producing a polymer powder, which comprises subjecting the powder to solid phase polymerization.