JPH0825355A - Nozzle for powdering polymer and grinding method - Google Patents

Abstract

PURPOSE:To grind a polymer at ordinary temp. or higher by constituting the orifice part provided to the bottom part of a nozzle of a first columnar orifice part and the second conical orifice part continuing thereto and positioning the first orifice part at the apex of the conical pedestal protruding from the bottom part and forming the inner surface of the first orifice part and the side surface of the conical pedestal into an acute angle shape. CONSTITUTION:A hole is provided to the bottom part 2 of the interior 1 of a nozzle so as to go toward the outside of the nozzle from the inside thereof and constituted of a first columnar orifice part 4 and the second orifice part 5 continuing thereto. The inlet of the first orifice part 4 is positioned at the apex of the conical pedestal 6 protruding from the bottom part 2 and the second orifice part 5 is formed into a fanwise conical shape so that one end thereof is connected to the first orifice part 4 and the other end thereof is opened to the outside. The crossing angle 13 of the inner surface 7 of the first orifice part 4 and the side surface 8 of the conical pedestal is formed into an acute angle and an annular blade shape 9 is formed to the leading end thereof. When a polymer is ground by this nozzle, the polymer can be ground at ordinary temp. or higher without allowing shearing force to act on the polymer and the deterioration of the polymer caused by grinding can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mechanical part for pulverizing a polymer and a pulverizing method thereof, and more particularly to a nozzle for pulverizing the polymer and a pulverizing method of the polymer at room temperature or under heating. .

[0002]

2. Description of the Related Art Pulverization of a polymer is carried out by a method in which the polymer is cooled and embrittled by liquid nitrogen or the like to be pulverized, or a method in which the refrigerant is mechanically pulverized by utilizing shear fracture without using such a refrigerant. However, the method of using a refrigerant such as liquid nitrogen has a large energy loss, and the cost of powdering is high due to the expensive equipment cost.

On the other hand, in the mechanical pulverization method utilizing shear fracture, it is difficult to effectively remove heat generated by shearing in order to prevent melting of the polymer due to heat generated during shear fracture, and deterioration and deterioration of the polymer due to shearing occur. There's a problem.

A polymer crushing method using high frequency vibration is also known, but it is not an industrially effective method because an expensive high frequency oscillator is required and the equipment is complicated.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides a powdered mechanical part which does not undergo freezing and pulverization with a large energy loss and does not deteriorate or deteriorate the polymer, and a method for pulverizing the polymer using the mechanical component. For more details, more specifically, a nozzle having a special structure that does not exert a shearing force on the polymer under normal temperature or higher conditions,
An object of the present invention is to provide a method for pulverizing a polymer using the nozzle.

[0006]

According to the present invention, a hole provided in a bottom portion of a nozzle is provided from the inside of the nozzle to the outside thereof.
It is composed of a substantially columnar first hole portion and a conical second hole portion which is connected to the first hole portion and opens to the outside of the nozzle while the cross-sectional shape continuously expands. The polymer powder which is located on the top of the conical pedestal formed so as to project from the bottom of the nozzle, and the inner surface of the first hole and the side surface of the conical pedestal substantially intersect at an acute angle to form an annular blade shape. The present invention relates to a method for pulverizing a polymer, which is a liquefying nozzle and which is pulverized by passing through the nozzle under pressure at a temperature of normal temperature or higher.

The inventors theoretically analyzed the relationship between the viscoelasticity of the polymer and the physical fracture, and as a result of diligent research, as a result, a nozzle with a special shape was formed in a certain physical state without using freezing or shearing. The inventors have reached the present invention by discovering that the polymer becomes a powder when passed.

Hereinafter, the nozzle of the present invention and the method for pulverizing a polymer using the nozzle will be described in detail. FIG.
FIG. 3 is a vertical sectional view of a nozzle of the present invention. The nozzle of the present invention is provided with a hole in the bottom portion 2 of the nozzle interior 1 from the inside of the nozzle toward the exterior 3. This hole is composed of a first hole portion 4 and a second hole portion 5. The first hole is columnar,
The inlet is located at the apex of the conical pedestal 6 protruding from the bottom inside the nozzle around the inlet. The second hole portion has a pyramidal shape whose cross-sectional shape continuously expands, one end of which is connected to the first hole portion and the other end of which is open to the outside of the nozzle.
The angle at which the inner surface 7 of the first hole and the side surface 8 of the conical pedestal intersect is an acute angle, and its tip forms an annular blade shape 9.

In the nozzle of the present invention, the number of holes provided in the nozzle may be one, but it is suitable to provide a plurality of holes from the viewpoint of powder productivity.

The first hole portion of the nozzle of the present invention has a columnar shape, and the hole diameters at positions near the inlet of the first hole portion and the second hole portion do not have to be exactly the same, but holes having the same hole diameter are used. The part is easy to process, and the powdering efficiency of the polymer is excellent. The shape of the cross section of the first hole is not particularly limited, and may be polygonal or circular. A circular cross section having a circular shape has a higher strength of the annular blade shape at the inlet of the first hole portion, and the hole can be easily formed.

In the nozzle of the present invention, when the inner diameter dimension 10 of the first hole portion is D, the height 12 from the lowest point of the side surface of the conical pedestal to the tip of the annular blade is 0.2 × D or more. ,
It is preferably 0.7 × D or less. If the height is less than 0.2 × D, a good polymer powder cannot be obtained, and if it is greater than 0.7 × D, not only the pressure required for pulverizing the polymer becomes high, but also the durability of the annular blade shape is improved. Sex becomes low. The height is more preferably 0.3 × D or more and 0.5 × D or less from the viewpoint of the pressure required for pulverizing the polymer, the mechanical strength of the annular blade shape and the pulverization efficiency.

The length 11 of the first hole portion is preferably 0.3 mm or more and 10 mm or less. If the length is less than 0.3 mm, the mechanical strength of the first hole becomes weak and it becomes impossible to withstand the pressure for pulverizing the polymer.
Further, if the length is larger than 10 mm, a high pressure is required for pulverizing the polymer, and the pulverization efficiency decreases. From the viewpoint of the pressure required for pulverizing the polymer and the mechanical strength of the nozzle, the length is more preferably 0.5 mm.
It is above 5 mm.

The second hole portion connected to the first hole portion has a cone-shaped opening toward the outside of the nozzle, but the cone-shaped spread angle is arbitrary. The shape of the cross section of the second hole may be polygonal or circular as in the case of the first hole, but circular is advantageous in terms of processing.

The inclination slope of the side surface 8 of the conical pedestal projecting from the bottom inside the nozzle may be constant or may be continuous or discontinuous (FIG. 2). The tip of the annular blade formed by the inner surface of the first hole and the side surface of the conical pedestal intersecting may be straight (Fig. 3) or sawtooth (Fig. 4), but the polymer can be used efficiently. A serrated annular edge is better for good grinding.

The side surface of the conical pedestal and the inner surface of the first hole intersect at an acute angle, and the angle 13 is in the range of 30 to 70 °. If the angle is less than 30 °, the mechanical strength of the conical pedestal will be weakened and the durability of the blade will be poor.
If it is larger than 0, a good polymer powder cannot be obtained.
In order to enhance the mechanical strength of the conical pedestal and the efficiency of crushing the polymer, the angle is more preferably in the range of 40 to 60 °.

Materials that can be used for the nozzle of the present invention are:
Metals such as iron and chrome, alloys such as stainless steel and bronze, ceramics and glass. A nozzle having a desired shape can be produced from these materials by cutting or casting.

Polymers that can be powdered with the nozzle of the present invention include polyolefins such as polyethylene and polypropylene, polyamides such as nylon-6, nylon-6,6 or nylon-12, and thermoplastic polymers such as polyesters and vulcanization crosslinks. Natural rubber, synthetic rubber,
Examples thereof include cross-linked polymers such as cross-linked polyethylene, and thermosetting polymers such as epoxy resins and phenol resins having low cross-linking density.

Powdering of these polymers by the nozzle of the present invention is carried out by pressurizing and extruding through the nozzle at a temperature below the melting point or glass transition point of the polymer.

In order to efficiently pulverize the polymer using the nozzle of the present invention, it is preferable to use a polymer which has been previously crushed to have a particle size of several mm or less. When the average particle diameter of the coarsely crushed polymer is M and the inner diameter dimension 13 of the first hole portion of the nozzle of the present invention is D, in terms of the pulverization efficiency of the polymer, the particle diameter and the particle size distribution of the obtained powder, D Is 0.1
It is preferably not less than × M and not more than 0.15 × M. D
Is less than 0.1 × M, the pressure required for pulverization is high and the pulverization efficiency is poor, while if it is greater than 0.15 × M, powder having a large particle size is included. By using a nozzle in which the inner diameter D of the first hole portion is set to 0.1 × M or more and 0.15 × M or less, the particle size distribution of the powder obtained is such that the minimum particle size is 0.1 × D and the maximum is The particle size is 2 × D, and 80% or more of powder has a particle size of 0.3 × D to 0.8 × D. Therefore,
Since the particle size M of the coarsely crushed polymer and the inner diameter dimension D of the first hole portion largely determine the particle size of the powder obtained by pulverization, both values are appropriately selected according to the required value of the powder particle size. If the powder obtained by the nozzle of the present invention is pulverized again by the nozzle having the inner diameter dimension of the first hole portion set from the average particle diameter of the powder, a powder having a smaller particle diameter can be obtained.

The pressure required for pulverization varies depending on the type of polymer and the heating temperature at the time of crushing, but the particle size of the polymer after crushing, the inner diameter and length of the first hole of the nozzle, the heating temperature at crushing If properly set, about 500kg / cm
² to about 2,000 kg / cm ² . For example, in the case of automobile tire rubber, the required pressure is about 2,000 kg.
/ Cm ² to about 500 kg / cm ² , specifically about 2,000 kg / cm ^{2 at} 20 ° C, about 1,000 kg / cm ² at 100 ° C, and about 6 at 160 ° C.
The pressure is 00 kg / cm ² .

To obtain a polymer powder using the nozzle of the present invention, it is necessary to press the crushed polymer at room temperature or under heating. A plunger type or screw type extruder can be used as the pressurizing device. The object can be achieved by connecting the nozzle of the present invention to the outlet of these extruders or by making the outlet nozzle of the extruder the structure of the nozzle of the present invention.

[00022]

The present invention will be described below with reference to examples, but the scope of the present invention is not limited by these examples.
The correspondence between the symbols used in the examples and the contents is as follows. M: Average particle size of coarsely pulverized polymer D: Inner diameter of first hole of nozzle L: Length of first hole of nozzle H: Ring from the lowest point on the side surface of the conical pedestal of the nozzle Height to the tip of the blade shape A ...... The angle between the side surface of the conical pedestal of the nozzle and the inner surface of the first hole

Example 1 An automobile tire composed of 30% natural rubber and 70% synthetic rubber was crushed with a crusher to obtain rubber chips. The M of this chip was 5 mm. It has two holes at the bottom of the nozzle, each D, L, H, A is the same, and D is 0.5m.
An iron nozzle having m and L of 1.5 mm, H of 0.18 mm, and A of 40 ° was connected to the outlet of a plunger type extruder that can be heated from the outside. The roughly crushed rubber chips were placed in an extruder and the cylinder was heated from the outside. When the temperature of the contents reaches 50 ° C, the extruder is operated at 1,80
A pressure of 0 kg / cm ² was applied to powderize the rubber. The obtained rubber powder has a minimum particle size of 50 μm and a maximum particle size of 1,0.
It was 00 μm. Measure the particle size distribution of the rubber powder and
A result of 1 was obtained.

[Table 1]

Example-2 There are four holes at the bottom of the nozzle, and D of each hole is 0.17 m.
m, L is 0.7 mm, H is 0.08 mm, A is 55 °, the nozzle is set at the exit of the screw extruder capable of heating, the cylinder temperature is 150 ° C., and the average particle size is 1 mm.
The cross-linked polyethylene pellets (1) were supplied from the material input port of the extruder and continuously extruded. The pressure applied to the nozzle was about 700 kg / cm ² . The obtained crosslinked polyethylene powder had a particle size of 15 μm to 300 μm, and the powder having a particle size of 45 μm to 120 μm accounted for 87% of all powders.

Example-3 It has four holes, D of each hole is 0.3 mm and L is 2.0 m.
m and H use 0.12 mm, A uses a 45 ° nozzle,
At a cylinder temperature of 120 ° C., a polypropylene type extruder was used to powderize polypropylene that had been crushed to an average particle size of 3 mm. A polypropylene powder having a particle size of 30 μm to 600 μm was obtained, and 85% of the total powder had a particle size of 90 μm to 240 μm.

Example 4 A pellet obtained by mixing equal amounts of black colored nylon-6,6 having an average particle size of 3 mm and uncolored nylon-6,6 having the same particle size was used, and the same nozzle as in Example 3 was used. Then, it was pulverized with a screw extruder having a cylinder temperature of 150 ° C. The particle size and particle size distribution of the obtained powder were almost the same as the results of Example 3. The above-mentioned mixed pellets were pulverized by an extruder with mechanical shearing force, and both powders were observed by an optical microscope. In the latter pulverization by the shearing method, kneading simultaneously occurs during shearing and pulverization, so that all the powder particles are black. On the other hand, since powdering with a nozzle does not involve kneading, the powder contained colored and uncolored particles equally. The melt viscosity of the powder by the nozzle method did not change as compared with that of the mixed pellets, but the melt viscosity of the powder by the shearing method was lowered.
This indicates that pulverization in an extruder in which mechanical shearing force acts causes breakage of polymer molecular chains.

[00027]

Since the nozzle of the present invention has a special structure at the inlet of the first hole of the nozzle, the polymer can be pulverized under a relatively low pressure and at room temperature or higher. Further, since the shearing force does not work at the time of pulverization, the polymer is not altered or deteriorated.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view (I) of a nozzle.

FIG. 2 is a vertical sectional view (II) of the nozzle.

FIG. 3 is a perspective view (I) of the conical pedestal of the nozzle.

FIG. 4 is a perspective view (II) of the conical pedestal of the nozzle.

[Explanation of symbols]

1 …… Inside of nozzle 2 …… Bottom of nozzle 3 …… Outside of nozzle 4 …… First hole of nozzle 5 …… Second hole of nozzle 6 …… Conical pedestal protruding from the bottom inside the nozzle 7 ...... Inner surface of first hole 8 ...... Side surface of conical pedestal 9 …… Annular blade shape 10 …… Inner diameter of first hole of nozzle 11 …… Length of first hole of nozzle 12 …… ... Height from the lowest point on the side surface of the conical pedestal of the nozzle to the tip of the annular blade 13 ... The angle between the side surface of the conical pedestal of the nozzle and the inner surface of the first hole

Claims (8)

[Claims] 1. A nozzle for pulverizing a polymer by passing it under pressure, wherein a hole provided at the bottom of the nozzle has a substantially columnar first hole from the inside to the outside of the nozzle. , A conical second hole opening to the outside of the nozzle while continuously expanding its cross-sectional shape, and the inlet of the first hole is formed so as to project from the bottom inside the nozzle around the inlet. A nozzle located on the top of the conical pedestal, wherein the inner surface of the first hole and the side surface of the conical pedestal intersect at a substantially acute angle to form an annular blade shape. 2. The nozzle according to claim 1, wherein the cross section of the first hole has a circular shape. 3. The nozzle according to claim 1 or 2, wherein the annular blade shape at the inlet of the first hole has a sawtooth shape in the circumferential direction. 4. The nozzle according to claim 1, wherein the acute angle at which the inner surface of the first hole portion and the side surface of the conical pedestal substantially intersect is in the range of 30 to 70 °. 5. The hole provided in the bottom of the nozzle is a substantially columnar first hole from the inside of the nozzle to the outside, and the outside of the nozzle is connected to the first hole while the cross-sectional shape continuously expands. Consists of a conical second hole opening at
The inlet of the first hole is located on the top of the conical pedestal formed by protruding from the bottom inside the nozzle around the inlet, and the inner surface of the first hole and the side surface of the conical pedestal intersect at a substantially acute angle to form an annular blade. A method of pulverizing a polymer, which comprises passing a polymer pressurized at a temperature equal to or lower than a melting point through a nozzle forming a shape. 6. The method of pulverizing a polymer according to claim 5, wherein the first hole is a nozzle having a circular cross section. 7. The fifth and sixth aspects, wherein the annular blade shape at the inlet of the first hole portion is a saw-toothed nozzle in the circumferential direction.
The method for pulverizing a polymer according to the item. 8. The nozzle according to claim 5, 6, or 7, which is a nozzle having an acute angle of 30 to 70 ° at which the inner surface of the first hole portion and the side surface of the conical pedestal substantially intersect. Method of grinding polymer.