JPS63151407A - Manufacture of thermoplastic resin compound - Google Patents

Abstract

PURPOSE:To obtain well-grained thermoplastic resin compounds having excellent extrusion stability in highly packed amount by a method in which the front face of a lower flat blade in a first stage is inclined toward the direction of raking up a mixture, and the upper blade in the first stage is inclined toward the direction of pushing down the mixture, and many of the second stage stirring flat blades are provided in a high-speed fluidizing type mixer. CONSTITUTION:A high-speed fluidizing type mixer consists of one set of mixers having three different functions. The stirring blade of the first stage mixer consists of upper and lower two stages of blades, in which the upper blade is of a puddle-type inclined toward the direction of pushing down a mixture by rotation, and the lower blade is of a flat type inclined toward the direction of raking up the mixture. In the second stage mixer, a mixture heated to a temperature higher than the melting point of thermoplastic resins is granulated into grains having solid fine powder on their surfaces. In the stirring blade, the lowest stage flat blade is gently inclined toward the direction of raking up the mixture, and flat blades are set over it in a multistaged manner. The mixture obtained in the second stage mixer is immediately discharged to the third stage high-speed fluidizing type mixer for cooling.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides inorganic fillers, organic fillers, and pigments #! Regarding the manufacturing method of thermoplastic resin compounds containing !, from an application standpoint, thermoplastic resin compounds used in extrusion molding, injection molding, blow molding, etc. J! ! Regarding the method of sending.

[Conventional technology]

Thermoplastic resins containing inorganic fillers or organic fillers are widely used in the synthetic resin industry for the purpose of improving heat resistance, rigidity, etc. of the resin.

Conventionally, methods using extruders, mixing rolls, Banbury mixers, kneaders, etc. have been known as methods for mixing these solid fillers with thermoplastic resins, and these methods are used to perform melt-kneading. It has been granulated into a form that is easy to mold using a molding machine and then supplied to a molder.

However, the above method requires steps of mixing and granulation, which is costly, and even if a cheap solid filler is added, the supplied mixture may end up being expensive.

In addition, when mixing solid fine powder and thermoplastic resin in a granular mixer, if the amount of solid fine powder blended increases, classification of both tends to occur, and therefore it is not recommended to increase the blended amount of solid fine powder. It's difficult and I'm sorry.

especially,? Most thermoplastic resins such as rideropyrene and polyethylene V are supplied to the molder in the form of pellets.9) When mixing solid fine powder with it, the amount of solid fine powder blended is at most 20% by weight. There were many cases.

When mixing solid fine powder and thermoplastic resin powder, it is possible to increase the blending ratio of solid fine powder, but the resulting mixture has a small bulk specific gravity, a large angle of repose, and poor fluidity. However, there were problems such as bridging in the hopper during molding using a twin-screw extruder, making it impossible to supply the product, and poor penetration in the single-screw extruder, resulting in unstable extrusion volume.

A method to solve these problems is to use a high-speed mixing mixer such as a Hey Shell Mixer (manufactured by Mitsui Miike Industries Co., Ltd.) or a Super Mixer (manufactured by Chikarawata Ura Co., Ltd.) to mix solid fine powder and thermoplastic resin powder. There is a method of mixing granules at high speed to create agglomerates covered with solid fine powder and partially fused thermoplastic resin powder, and then grinding this agglomerate to a particle size that can be extruded. However, this method requires a very long time for mixing, and in some cases it took more than 20 minutes for one patch). It cannot be said that this method is advantageous in terms of energy compared to the illetizing method using an extruder.

[Problem that the invention seeks to solve]

The purpose of the present invention is to solve the above-mentioned problems such as cost, limitation of mixing amount in the case of tri-blend, and instability of extrusion, eliminate the granulation process such as pelletizing, and supply inexpensive raw materials. It is an object of the present invention to provide a method for backing a thermoplastic resin powder having a uniform particle size, which has a high optical loading and excellent extrusion stability, which could not be achieved by tri-blending.

When the solid fine powder and the thermoplastic resin powder are mixed using a high-speed fluid mixer such as the above-mentioned Henschel mixer, Suit mixer, or one mixer, such that the peripheral speed of the stirring blade is 35 to 40 m/sec. The temperature of the mixture rises due to the frictional heat between the mixture, the stirring blade, the tank wall, and the powder particles. Finally, the melting point of the thermoplastic resin is exceeded and the solid fine powder adheres to the surface of the thermoplastic resin powder, and the thermoplastic resin powder coated with the solid fine powder partially fuses and forms a moderate amount. It reaches a granular state. If this process is further controlled by the motor current of the high-speed fluid mixer, the classification phenomenon during transportation and the bridging phenomenon in the extruder will not occur, and the product will have excellent quantitative stability.
A highly filled thermoplastic compound is obtained.

However, when the blending ratio of solid fine powder increases, it takes time for the mixture to become a suitable granule.
When the amount of solid fine powder blended is 50% by weight or more,! It can take anywhere from 20 minutes to over an hour to complete patch mixing, which is very inefficient. Therefore, for example, when molding is performed using an extruder with an extrusion rate of 600 kIP per hour, the capacity of the mixer is 1
0001 or more, which not only increases equipment costs but also makes it technically difficult to obtain a granular mixture.

In order to solve the above problems, the present inventors researched a highly efficient and compact granulation mechanism. As a result, a thermoplastic resin powder mixture highly filled with solid fine powder was mixed and granulated using a high-speed fluid mixer. In the process of mixing, most of the time required for mixing is consumed in raising the temperature until it exceeds the melting point of the thermoplastic resin and the stirring resistance begins to rise gradually, and the stirring resistance gradually increases. Don't overlook the fact that once you start, granulation progresses rapidly! Just in case. Furthermore, the time required for mixing and granulation is shortened, and granulation is more easily controlled.
It was found that it is very effective to separate the heating process and granulation perst in a high-speed fluid mixer and use stirring blades suitable for each process. .

[A precautionary measure to resolve the problem]

The present invention uses a high-speed fluid mixer having stirring blades capable of rapidly heating and mixing a thermoplastic resin powder mixture containing 20% by weight or more of solid fine powder in the first stage, and in the second stage. Using a high-speed fluid mixer having stirring blades that granulates the mixture heated to a temperature higher than the melting point of the thermoplastic resin to produce granules in which the solid fine powder is attached to the surface of the thermoplastic resin powder, In a method for producing a thermoplastic resin compound using a mixer having stirring blades that rapidly cools the granulated product to a temperature below the melting point of the thermoplastic resin in the third stage,
The stirring blade of the first stage high-speed flow mixer consists of two stages, upper and lower.The upper blade is a nonadole blade that is inclined in the direction of pressing down the mixture by rotation, and the lower blade is a flat blade, and the front side of the stirring blade is The stirring blade of the second-stage high-speed fluid mixer has a structure with many flat blades, and the front surface of the lowest blade is inclined in the direction of scraping up the mixture. It is characterized by what it does.

The high-speed fluid mixer according to the present invention is configured as a set of mixers having three different functions.

Kayazu: The first stage mixer is equipped with stirring blades that raise the temperature of the mixture as quickly as possible and at the same time improve the physical dispersion of the solid fine powder and thermoplastic resin powder. The blades are composed of upper and lower blades in two stages, and preferably rotate at a circumferential speed of 35 to 60 ml/sec. Furthermore, the outer wall of the tank of the mixer has a structure that can be heated with a heater, heating oil, steam, or the like.

Among the stirring blades, the upper blade is an AI dollar blade inclined in the direction of pushing the mixture downward by rotation, and the lower blade is a flat blade inclined N in the direction of stirring up the mixture.

The lower blades work to fluidize the mixture and circulate it within the tank, while the upper blades work to push the mixture down by rotation as described above, thereby consolidating the mixture. The rotation of the blades increases the coefficient of friction, which also has a synergistic effect with the lower blades, increasing the amount of heat generated by stirring.

Due to the action of this upper blade, the temperature rise rate is considerably faster than that of a normal high-speed fluid mixer.

The upper blades of the housing octopus have a suction effect that quickly sends all of the mixture lifted upward from the upper blades onto the inner wall of the tank by the lower blades downwards, which is also useful for mixing. Generally speaking, there are favorable conditions for the upper and lower blades used in the present invention.

First of all, the upper blade has an angle of 15° to 7° with the horizontal plane.
5'' is preferred, and those in the range of 3011 to 606 are more preferred, and when the angle is greater than 75'',
Mixed! This is because the effect of pressing down the blade 171 will be weakened, and if it is less than 15'', the effective area (vertical area of the blade) where the blade actually acts on the mixture will be small, making it ineffective.

Next is the wing span of the upper blade, which is preferably 8 to 25 inches of the tank diameter! L<, 10 to 20% is more preferable.

If it is less than 8%, the effect of pressing the mixture downward becomes weak, and if it exceeds f&25'%, the circulation movement of the mixture is inhibited, causing problems in the mixing itself.

The length of the upper blade is preferably 85% or more of the tank diameter,
Furthermore, it is desirable to set it to 90% or more.

This is because if the blade length is less than 85%, mixing will not be successful.

On the other hand, regarding the lower blade, in order to sufficiently fluidize the mixture and eliminate stationary parts, the thickness of the blade is preferably set to 03 to 12% of the tank height, and more preferably 4 to 8%. If the thickness of the lower blade is less than 3% of the tank height, it will be difficult to fluidize the mixture sufficiently, and if it exceeds 12% of the tank height, the power at startup will be excessive, so it is preferable. It's not right.

The blade length of the lower blade is preferably 85 inches or more of the tank diameter, more preferably 90% or more. If the blade length is less than 85%, it becomes difficult to fluidize the mixture.

Note that the clearance between the lower blade and the tank bottom is desirably kept within a range of 1.0 to 2.0 mm in order to prevent the mixture from getting caught.

Furthermore, in the present invention, important conditions have been found regarding the energy consumption of the upper and lower blades.

That is, if we define the following power formula E of the high-speed flow mixer proposed by A. M. Rastogutsev and H. (N. P.) Popov as the energy consumption per unit time of the blade, then the unit time of the upper blade It is desirable that the ratio EU/ED of the energy consumed per unit to the energy consumed by the lower blade ED be in the range of 0.5 to 1.5.

E=C2a+””L3.5(bain C1)”68H
"74S"19#H (KW) However, in the above formula, C2
: resistance coefficient in flow, ω: angular velocity (c/5-e),
L: Blade length - 1b = Blade width ←), α: Inclination angle (degrees), H: Height of mixture layer on the blade ←), S: Gap between blade edge and tank inner wall - 1゛ρ Y = Bulk density of mixture (kg/
3) If U/ED is less than 0.5, the effect of the upper blade will not be fully demonstrated, and if E./ED exceeds 1.5, the circulation of the mixture in the tank will be reduced. This causes problems in mixing the solid fine powder and the thermoplastic resin powder.

Now, when the temperature of the mixture exceeds the melting point t of the thermoplastic resin by the first-stage mixer and the stirring resistance of the mixing system begins to increase, the mixture must be immediately discharged to the second-stage mixer. No.

The temperature at which the stirring resistance begins to increase varies depending on the particle size of the thermoplastic resin powder and the amount of solid fine powder blended, but it can be said that the larger the particle size of the thermoplastic 71 fat powder granule, the higher the blend of solid fine powder. The higher the amount, the higher the price.

The second stage mixer is equipped with stirring blades that raise the temperature above the melting point of the thermoplastic resin, granulate the mixture, and produce a granulated product with solid fine powder attached to the surface of the thermoplastic resin powder. ing.

When the temperature of the mixture reaches the melting point of the thermoplastic resin or higher, the previously solid resin becomes a melt, solid fine powder adheres to the resin surface, and some of it is transported into the interior. ), the amount of free solid fine powder is reduced.

Therefore, the probability that the molten resins come into contact with each other increases, the stirring resistance of the entire mixture increases rapidly, and accordingly, the mixture rapidly becomes granulated.

Therefore, in this region, the shape of the stirring blade and the stirring speed must be specially controlled. The stirring blade used is one in which the flat blade at the lowest stage is gently flN in the direction of stirring up the mixture, and the flat blades are arranged in multiple stages above it. The circumferential speed of the stirring blade is 35 to 40 m/sec.
c is preferred, and it is preferable that the granular shape of the mixture is determined by the electric power or current of the drive motor of the mixer rather than by temperature. If it is desired to further make the grain size uniform, it is preferable to reduce the circumferential speed of the blade to 15 to 20 m/sea at the point when the electric current of the driving motor suddenly increases, and to control the blade using electric power or current.

There are also more preferable conditions for the stirring blades of this second-stage high-speed fluid mixer.

Among the stirring blades, the lowest blade works to fluidize the mixture, while the upper blade gives rotational motion to the mixture, causing the molten thermoplastic resin particles to fuse together and form a large It serves to prevent clumping. Therefore,
It is preferable that the plane of each blade in the traveling direction forms an acute angle of 30° or less with respect to the horizontal plane. The interval between the top and bottom blades is preferably in the range of 30 to 70% of that of the stallion, and the number of stages in each blade is preferably 2 to 5. Furthermore, an important condition for the stirring blades of the second-stage high-speed fluid mixer is that the initial energy consumption per unit time of the blades is in the range of 0.15 to 0.35 KJ/see per 1 yu of the mixture. It is even more preferable if it is in the range of 0.2 to 0.3 KJ/sse. When the energy consumption is less than 0.15 KJ/S・C, the progress of granulation becomes very slow.
``If it exceeds 1 ft O.
This results in a compound that cannot be extruded.

The appropriate granule state obtained in the second-stage high-speed flow mixer is achieved at a temperature 10 to 80°C higher than the melting point of the resin, depending on the ratio of solid fine powder and thermoplastic resin powder. If it is not cooled immediately, the entire mixture will stick together and form one large lump. Therefore, once the desired granule state has been obtained in this step, the mixture must be immediately discharged to the third stage cooling high-flow mixer.

In addition to stirring blades, the third-stage high-speed fluid mixer has a suitable cooling device, such as a forced water cooling jacket, and has a structure with a large cooling surface area. The main purpose of stirring here is to uniformly supply cold heat to the contents, so the peripheral speed is 5 to 2.
A range of 0 m/sec is sufficient.

By the way, the properties of the condensate necessary for extrusion molding machines and injection molding machines are first of all that it needs to have a small particle size so that it can fit into the screw of the molding machine, and generally the diameter is 5.
The size must be less than or equal to w.

Therefore, in the present invention, in order to suppress the occurrence of bridging in the hole 141-, and to produce a compound having an appropriate particle size that has good feedability in the screen and the
The process in which the thermoplastic resin particles coated with solid fine powder grow to an appropriate size and become granulated in the third stage is detected by the temperature of the mixture and the motor load, and as soon as the temperature reaches a predetermined level, the process is carried out in the third stage. Discharge into a blender to stop particle growth by rapid cooling.

As is clear from the above, the present invention includes a rapid heating mechanism in the first stage,
Combined with a three-way mixer that has a granulation mechanism in the second stage and a forced cooling mechanism in the third stage, the temperature control system for the mixture allows for highly efficient particle size control that cannot be achieved with conventional high-speed mixers. It is hoped that it will be possible to manufacture a uniform compound.

The solid fine powder used in the present invention includes inorganic fillers such as Merck, mica, calcium carbonate, graphite, titanium dioxide, potassium titanate, clay, silica, alumina, and glass, pulp, waste paper, fir, cotton, and silk. , organic fillers such as hemp and synthetic fibers, and pigments. Two or more of these solid fine powders may be used in combination. The solid fine powder is mixed in an amount of 20 iCt% or more with respect to the thermoplastic resin powder. 20
If the amount is less than % by weight, the meaning of mixing solid fine powder becomes weak.

The upper limit of the mixing amount is 85% by weight in the case of inorganic fillers. Due to physical property limitations of the final compound used,
Practically speaking, the amount of inorganic filler added is 20% to 60% by weight! Most of the items fall within the -% range. Preferably, the amount of the cased organic filler mixed is at most 60% by weight.

Furthermore, the thermoplastic resin powder used in the present invention may literally be powder, granules, or a mixture thereof. Examples of the thermoplastic resin include polyethylene, teripropylene, polyvinyl chloride, ethylene-propylene copolymer, Most of the materials generally used in the molding field can be used, such as ethylene-vinyl acetate copolymer, polybutene, nylon-6, nylon-66, and nylon-12.

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples and Comparative Examples.

Example 1 Polypropylene (MFR=0.7, li'/1
0 min, trade name Showa Aroma-8K711, manufactured by Showa Denko K.K.)) and graphite (average particle size 3μ) 50% by weight were mixed in a tank with a jacket temperature of 130°C and a tank volume of 1001. Pour into the first stage high-speed fluid mixer, and the blade rotation speed is 1350 rpm.
Start mixing while rotating the stirring blade.

After 5 minutes, the temperature of the mixture reached 170°C, so it was immediately discharged to the second stage, a high-speed fluid mixer with a tank capacity of 1001, and mixed for 3 minutes while keeping the stirring blade rotation speed at 1350 rpm. is 1.8 times as much as immediately after starting, which is 65A.
When the temperature of the mixture reaches 190°C, it is discharged to the third stage high-speed fluid mixer (cooling mixer), and the granulated material is rapidly cooled to 80°C, and then the compound is taken out.

Please note that the total time required for mixing was 8 minutes.

The inner diameter of the stirring tank of the first stage high-speed fluid mixer is 5.
7c! n, as the stirring blade, the upper blade has a blade width of 7α, the blade length is 54 m, and is tilted in the direction of pressing the mixture downward by rotation (the angle made with the horizontal plane is 60 degrees), the lower blade is 3 pieces thick, Use a flat blade with a blade length of 55 on and the front side of the blade slanted in the direction of scraping up the mixture. The energy consumption ratio EU/ED of the upper and lower blades per unit time is 0.89
Met. In addition, the second-stage high-speed flow type mixer has a stirring blade at the lowest stage with a thickness of 2.6 cW1 and a blade length of 55 IyR, and the front surface of the blade is inclined in the direction of scraping up the mixture (the angle with the horizontal plane is 15'). t, is a nenpei feather, and has a thickness of 5
Use a stirring blade with four stages of m flat blades. The angle between each blade and the plane in the traveling direction was 15°.

Seriously, the initial energy consumption in the stirring blade is 0.2
5 KJ/ See and remember.

The bulk specific gravity of the obtained compound was 0.66, the weight average particle diameter was Visooμ, and the angle of repose was 45''.

Next, this compound was put into a 65cm single-screw extruder, and the width was 650cm and the wall thickness was 0 under the conditions of a set temperature of 220℃, a screw rotation speed of 8゜rpm, and an extrusion speed of 170 kl/hr.
．． A 5-inch sheet was molded. When the variation in extrusion amount was measured, it was ±1.5%, indicating that extremely stable molding was possible. The filler dispersion of this sheet was also examined and was found to be extremely good.

Comparative Example 1 A mixture having the same composition as Example 1 was heated at a jacket temperature of 130°C.
The mixture was put into a high-speed mixer (Kawata-Sabi Super Mixer Co., Ltd.) with a capacity of 1,001 liters heated to 1,000 rpm, and mixing was started while keeping the rotational speed of the stirring blade at 135 rpm. After 20 minutes, the motor current started to rise, and after 2 minutes, the motor current reached 1.8 times the steady state, so the contents were completely discharged. The total time required for mixing was 22 minutes. Ratio of energy consumption per unit time of stirring blades of this mixer EU/E
D is 0.40.

〔Effect of the invention〕

According to the manufacturing method of the present invention, since the granulation process such as pelletizing is carried out through oil channels, it is possible to supply inexpensive raw materials to extrusion molding machines, injection molding machines, etc. It is possible to provide an L thermoplastic resin compound with a high light loading and high efficiency, which has never been possible before, and which has excellent extrusion stability and uniform particle diameter.

Claims (6)

[Claims] (1) The first stage uses a high-speed fluid mixer with stirring blades that can rapidly heat up and mix the thermoplastic resin powder mixture containing 20% by weight or more of solid fine powder, and the second stage uses a thermoplastic resin powder mixture containing 20% by weight or more of solid fine powder. Using a high-speed fluid mixer having stirring blades for granulating the mixture heated to a temperature higher than the melting point of the resin to produce granules in which the solid fine powder is attached to the surface of the thermoplastic resin powder, a third In the method for producing a thermoplastic resin compound using a high-speed fluid mixer having stirring blades for rapidly cooling the granulated product to a temperature below the melting point of the thermoplastic resin in each stage, the first stage high-speed fluid mixer The stirring blade consists of two stages of upper and lower blades, the upper blade is a paddle blade that is inclined in the direction of pressing down the mixture by rotation, the lower blade is a flat blade whose front surface is inclined in the direction of scraping up the mixture, and A thermoplastic resin characterized in that the stirring blade of the second-stage high-speed flow type mixer has a structure in which a large number of flat blades are arranged, and the front surface of the lowest blade is inclined in a direction to scrape up the mixture. Method of manufacturing compounds. (2) In the stirring blade of the first-stage high-speed fluid mixer, the angle between the upper blade and the horizontal plane is 15° to 75°;
The method for producing a thermoplastic resin compound according to claim 1, wherein the blade span is 8 to 25% of the tank diameter, and the blade length is 85% or more of the tank diameter. (3) A patent characterized in that, in the stirring blade of the first-stage high-speed fluid mixer, the plate thickness of the lower blade is 3 to 12% of the tank height, and the blade length is 85% or more of the tank diameter. Claims No. (
1) A method for producing a thermoplastic resin compound as described in section 1). (4) In the stirring blades of the first-stage high-speed fluid mixer, the ratio E of the energy consumption E_U of the upper blade per unit time to the energy consumption E_D of the lower blade defined below.
The method for producing a thermoplastic resin compound according to claim (1), wherein _U/E_D is 0.5 to 1.5. E=C_2ω^2^. ^5^6L^3^. ^5 (bsi
nα)＾0＾. ^6^8H^0^. ^7^4S^0^.
^1^9ρ_H (KW) where C_2: drag coefficient in flow, ω: angular velocity (C/sec), L: blade length (m),
b: Blade span (m), α: Inclination angle (degrees), H: Height of the mixture layer on the blade (m), S: Gap between the edge of the blade and the tank inner wall (m), ρ_H: Mixture Bulk density (kg/m
^3). (5) In the stirring blades of the second-stage high-speed fluid mixer, the surface of each blade in the advancing direction forms an acute angle of 30° or less with respect to a horizontal plane. 1) A method for producing a thermoplastic resin compound as described in section 1). (6) In the stirring blade of the second-stage high-speed fluid mixer, the initial energy consumption per unit time of the blade is in the range of 0.15 to 0.35 KJ/sec for the mixture. A method for producing a thermoplastic resin compound according to claim (1).