JPH0467910A - Die for underwater granulator - Google Patents

Abstract

PURPOSE:To easily form a pellet having a particle size over a wide range from various resins in a clean shape without generating clogging by providing a heat insulating layer composed of a polar group-containing resin having a specified m.p. to the side surface of the cutter of a die. CONSTITUTION:A heat insulating layer is provided to the side surface (the outlet surface of an extruded strand) of the cutter of a die body. As a polar group-containing resin susceptible to the formation of the heat insulating layer, any resin containing one or more kind of polar groups and having an m.p. of 250 deg.C or higher can be used. As the polar group, for example, -S-, -O-, -CO-, -SO2-, >N-CO- or -O-CO-O- can be designated. Aong them, -O- and -CO- are especially pref.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a die used as an extruder die, a pellet die, etc. used in the technical field of processing plastic materials, and particularly to a die used in an underwater granulation device, etc. The present invention relates to a die that can be suitably used in a granulation device.

[Prior Art] Granulation of plastic materials such as plastics is carried out as follows.

That is, the plasticized melt is extruded as a strand through an extrusion hole provided in a die (die plate) of an extruder, and the extruded strand is cut with a cutter at the exit surface of the extrusion hole. .

However, in the conventional die, since the die is heated to a high temperature higher than the melting point or softening point of the plastic material, heat is conducted to the cutter disposed close to the extrusion surface of the die. As a result, the plastic material cut by the cutter does not solidify and remains in a semi-molten state, causing the pellets to adhere to each other, making it impossible to manufacture individual pellets. There are some problems.

Alternatively, the semi-molten pellets may adhere to the cutter and cannot be peeled off, and in such a case, subsequent pellets may adhere to the preceding pellets one after another, making it impossible to achieve satisfactory granulation. There are also points.

Therefore, as a measure to prevent such pellets from adhering to the cutter, the method of rapidly cooling the strand and the cutter itself immediately after extrusion from the die with a refrigerant such as water within an appropriate temperature range, especially contact with the refrigerant, is proposed. The so-called underwater granulation method, which involves cutting at the bottom, is known.

Recently, we have developed an underwater granulation system that has been improved to prevent adhesion to the cutter and maintain good workability and long-term operation.We have installed a refrigerant passage inside the machine to cool it to an appropriate temperature. A granulating device has been proposed in which the strands are cut while efficiently cooling the strands by causing a refrigerant such as water to flow out from the passage (Japanese Patent Application Laid-Open No. 1983-1999).
279905).

However, in the so-called underwater granulation method using a refrigerant such as water, although it is possible to prevent the pellet from adhering to the cutter, the extrusion hole (nozzle, resin hole) of the die can be prevented.
problems such as clogging, making extrusion operations difficult, or resin pellets and their residue adhering to the exit surface of the die, or the extrudate or the inner surface of the die nozzle (especially the tip) being in a semi-molten state. There are new problems such as the inability to form a well-shaped pellet due to the formation of particles and adhesion.

These new problems occur because cooling is performed very close to the cutter side surface of the die (die plate), and the temperature of the cutter side surface of the die drops too much due to the action of the refrigerant. Even when using not only a conventional granulator but also an improved granulator (underwater granulator) as disclosed in the above-mentioned publication, as long as a conventional die is used, this problem occurs.

As a method to prevent the occurrence of clogging, a hardened layer ( A method of heating a die so as to provide a protective layer (protective layer) by coating, and furthermore, to maintain a sufficiently molten state of the plastic material even at the tip of the resin hole (nozzle) in the die (for example, Japanese Patent Application Laid-Open No. 126705/1983 (e.g., the method described in Publication No. 1) has been proposed.

However, such die heating and coating methods may vary depending on the type of molded product and the nozzle hole diameter.
Sufficient prevention effects against clogging and adhesion to the nozzle and die surfaces cannot be obtained, and even if clogging can be prevented, extrudates cannot avoid adhesion to the inner surface of the nozzle, making it difficult to maintain a clean shape. Formation of granules (vellets) is difficult.

For example, it is difficult to obtain a well-shaped pellet with polyethylene or hot melt adhesive resin, etc., and it is not easy to obtain a well-shaped pellet with polystyrene even if the area around the nozzle is heated. Thermoplastic resins such as nylon, which undergo rapid changes in temperature, are difficult to pelletize. Further, in any thermoplastic resin, if the nozzle diameter is made small, problems such as clogging of the resin occur, and therefore, it is impossible to manufacture small-diameter pellets.

That is, conventional dies, particularly dies for underwater granulation equipment, have various unresolved problems as described above.

[Invention or problem to be solved] The present invention has been made in view of the above circumstances.

The purpose of the present invention is to solve the above-mentioned problems, and particularly when used in an underwater granulation method, various resins such as general-purpose thermoplastic resins can be made into granules of various diameters ranging from small diameter ones. It is an object of the present invention to provide a die for a granulation device that can be easily formed as a pellet without clogging and in a clean shape.

[Means for Solving the Problems] As a result of extensive research to solve the above problems, the present inventors have developed an appropriate heat insulating layer on the exit surface (force/enter side surface) of the conventional die. The idea was that if provided, it would be possible to effectively prevent the cooling effect of the refrigerant on the dice in the underwater granulation method, and the above objective could be easily achieved.

Based on this idea, the present inventors conducted various studies on the material of the heat insulating layer, etc., and as a result, created a heat insulating layer made of a resin having a polar group above a specific melting point or a resin composition containing this on the exit surface. The present inventors have discovered that the above object can be satisfactorily achieved by a new type of die, that is, a die with a heat insulating layer, and have completed the present invention.

That is, the present invention is a die for a granulator, characterized in that the cutter side surface of the die is provided with a heat insulating layer containing a polar group-containing resin having a melting point of 250° C. or higher.

The present invention will be explained in detail below.

The die of the present invention is provided with the above-mentioned heat insulating layer on the cutter side surface of the die base (exit surface of the extruded strand).

As the polar group-containing resin that can be used to form this heat insulating layer, various known resins may be used as long as they contain one or more types of polar groups and have a melting point of 250°C or higher. I can do it.

In general, depending on the degree of crystallization and composition of resin,
Although it is not possible to define a clear melting point, in the present invention, the softening point is used as the melting point in such a case.

Examples of the polar group include -5--0-1-〇〇-1-SO, -1)N-CO--o-co-o-, and the like. Among these, especially -〇-1
-CO- etc. are preferred.

In addition, the polymer compound as a constituent component of the polar group-containing resin may be a resin containing one type of various polar groups such as the above-mentioned polar groups, or a resin containing two or more types. It is also desirable that these polar groups are normally contained at least in the main chain of the polymer.

Specific examples of the polar group-containing resin used in the heat insulation layer include polycarbonate (PC), polyphenylene sulfide (PPS), aromatic polyether sulfone (PES), and polyether ether ketone (PEE).
K), aromatic polyethers such as polycyanoaryl ether, aromatic polyimide polyparabanic acid resin, and the like. In addition, these PC, PPS, PES
, aromatic polyethers, aromatic polyimides, etc., each type of aromatic ring unit (for example, phenylene unit,
biphenyl units, bisphenol units, naphthalene units, etc., and those having various substituents on their aromatic rings), and various resins combining these with the above polar groups (
Homopolymers, copolymers, and copolymers include random types, block types, graft types, alternating types, etc.), but in the present invention, these resins are appropriately selected. It can be used.

Among these, aromatic polyethers are preferred, and PEEK is particularly preferred.

In addition, these polar group-containing resins may be used alone or in combination of two or more types. However, in order to further improve its properties, it is preferable that this heat insulating layer contains a filler together with the polar group-containing resin, and if desired, it may contain other fillers. Components may also be included.

In many fields where resins are used, the filler is used as a reinforcing material, a heat resistance improving material, a thermal expansion coefficient adjusting material, etc., mainly to improve mechanical properties such as strength and abrasion resistance. Various organic fillers or inorganic fillers such as particulate or fibrous fillers may be used, which are appropriately blended according to the purpose, and inorganic fillers are preferably used.

As this inorganic filler, for example, glass fiber (O
F), glass beads (QB), carbon fiber (CF), carbon black (CB), metal fiber (MF), metal powder, titanate, alumina.

Various oxides such as silica, various composite oxides such as talc and mica (including oxyacids such as silicates, carbonates, titanates, and sulfates), fibrous magnesium oxysulfate, etc. I can do it.

Among these, for example, CF and QB can be particularly preferably used depending on the purpose.

The blending ratio of these inorganic fillers may be appropriately set depending on the type of inorganic filler used, the type of resin, etc., or the purpose of improving the properties of the heat insulating layer.

Examples of the organic filler include fluororesin powder and fluororesin fiber.

It should be noted that these fillers may be used alone or in combination of two or more, as desired.

In addition, the ingredients for the above-mentioned functions include, for example, antioxidants,
Various additives such as stabilizers such as weather resistance improvers, dispersibility improvers, adhesion improvers, and plasticizers, and resins other than the polar group-containing resins can be mentioned. Incidentally, these are added as appropriate within a range that does not impede the object of the present invention, and may be used singly or in combination of two or more.

In the die of the present invention, the die main body for forming the heat insulating layer may be not only the die used in conventional granulation equipment but also various types of dies (single-hole die with a single nozzle, die with two nozzles, etc.). It is also possible to use a porous die having the above-mentioned properties. Among these, a die main body for an underwater granulation device is preferable because it can exhibit the effects of the present invention particularly markedly.

In the die of the present invention, the heat insulating layer is provided on the strand exit surface (cutter side surface) of the die body.

This heat insulating layer may have a single layer structure or a multi-layer structure of two or more layers. Usually, the adhesive strength of the heat insulating layer to the die body, the strength of the heat insulating layer, the abrasion resistance of the center side surface, and the heat insulation The type of polar group-containing resin used, the type of filler, the blending ratio, etc. are appropriately selected in consideration of the mechanical strength of the entire layer, etc., and the multilayer structure is made up of layers with different compositions (i.e., properties). It is preferable to have a structure.

An example of the multilayer structure of the heat insulating layer in this preferred embodiment is shown in FIG.

In the example shown in FIG. 1, on the cutter side surface of the die body I, an adhesive layer l made of a polar group-containing resin, an intermediate layer 2 made of a composition of a polar group-containing resin and carbon fiber (CF),
A heat insulating layer with a three-layer structure consisting of a surface layer 3 made of a composition of a polar group-containing resin and glass beads (GB).
The heat insulating layer (2) and the die body (I) constitute an example of the die of the present invention.

For the adhesive layer 1, a polar group-containing resin (preferably PEEK) that does not contain fillers is used, taking into consideration the adhesion with the die body I (usually made of metal or ceramic alloy). is mainly made of a polar group-containing resin (preferably PEE) in order to improve mechanical strength, heat resistance (e.g. self-shaping at high temperatures), and to bring the coefficient of thermal expansion of the heat insulating layer close to that of the die body. A composition containing a fibrous inorganic filler (CF in this example) is used, and the first surface layer 3 contains a polar group-containing resin (preferably PEEK) in the form of particles to mainly improve wear resistance. A composition containing an inorganic filler (OB in this example) is used.

In this way, the heat insulating layer ■ has an adhesive layer 1 which has excellent adhesion to the die body I, and the intermediate composition J! which can further improve the mechanical strength and heat resistance of the heat insulating layer ■ itself By adopting a three-layer structure consisting of F2 and a surface layer 3 having a composition that can further prevent wear caused by cutters and granules, the effects of the present invention can be sufficiently and stably exhibited, and the die of the present invention can be further improved. It is possible to further improve performance.

In the die of the present invention, the thickness of the heat insulating layer is
Normally, it is appropriate to set it appropriately in the range of 0.5 to 1.5 mm. If the thickness is less than 0.5 mm, the effect as a heat insulating layer may not be fully demonstrated; on the other hand, 1.
If it exceeds 5mm.

The heat insulating layer easily peels off from the die body.

Further, when the heat insulating layer has a three-layer structure as illustrated in FIG. 1, the thickness of the surface M3 is usually 0.2 mm or less, and the thickness of the intermediate layer 2 is usually 0.5 ~1.5m
m, and the thickness of the adhesive layer l is 1, usually 0.2.
mm or less, and the total thickness of the heat insulating layer is 1 usually, 0.
It is appropriate to set it in the range of 5 to 1.5 mm. Note that it is desirable that the thickness of the adhesive layer 1 be as thin as possible within a range that maintains sufficient adhesion. This is because by making the adhesive layer 1 thinner, the properties such as mechanical strength, heat resistance, and thermal expansion coefficient adjustment effect based on the intergrowth layer 2 can be more effectively exhibited.

The die of the present invention can be manufactured by coating the predetermined polar group-containing resin or its composition on the cutter side surface of a die body of a desired type, and applying a predetermined heat insulating layer. It can be suitably manufactured by a method of providing.

This coating can be done by various methods using various application methods, such as roll coater method, gravure coater method, spray coater method, brush coating method, etc., or usually, for example, spray coating method, etc. A powder coating method using a method is preferably employed.

In this way, various types of dies (i.e., dies of the present invention) in which the above-mentioned heat insulating layer is formed on the cutter side surface of various types of dies (dice bodies) of desired types, such as conventional dies (dice bodies), can be used. You can get it.

The die of the present invention is provided with a heat insulating layer made of a specific resin or resin composition having excellent heat insulation properties and excellent mechanical properties, heat resistance, etc. on the cutter side surface. When performing underwater granulation using an underwater granulator, the heat insulating effect of the heat insulating layer can sufficiently prevent the die temperature from decreasing due to the refrigerant used on the cutter side, thus solving the conventional problem. As a result, it is possible to sufficiently prevent nozzle clogging and adhesion (or retention) of resin on the inner surface and outlet of the nozzle due to a drop in temperature of the die nozzle. , it is possible to stably granulate into a regular shape without clogging.

In addition, for the same reason, even when the nozzle diameter is small, stable granulation is possible in the same way as described above, and it is now possible to produce small-diameter granules (pellets) with high productivity, which has been difficult in the past. can.

Note that the die of the present invention can be applied as a die for other granulation equipment other than the underwater granulation equipment or a more general extruder, if desired.

[Effects of the Invention] According to the present invention, especially when applied to an underwater granulation device, granules (bellets) of general-purpose thermoplastic resin, etc. having various diameters ranging from large diameters to small diameters can be prevented from clogging. Therefore, it is possible to provide a die for a granulation device that can be easily formed without any problems and has a clean shape.

[Examples] Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

(Examples 1 and 2) The die body was a commercially available die (model: PASC21).
-H3, nozzle diameter: 3mm, number of nozzles: 8) and commercially available dice (model: PASC21-H3, nozzle diameter: 0.
6 mm, number of nozzles: 8), a heat insulating layer with a three-layer structure shown in Fig. 1 was provided on the exit surface of each strand (cutter side surface) using a powder coating method, and two types of dies with heat insulating layers were formed. Created.

In addition, in this three-layer structure, the adhesive layer l, the intermediate layer 2, and the surface l! ! ! Resin or resin set dt used to form 3
The material and the thickness of each layer were as follows.

Adhesive layer 1: PEEK; approx. 0.1 mm Intermediate layer 2: PEEK+CF; approx. 0.8 mm Surface layer 3: PEEK+GB; approx. 0.1 mm [However, the above PEEK may be commercially available polyether ether ketone (manufactured by ICI) The CF is commercially available carbon fiber! 1 (manufactured by Toshiba Co., Ltd.: trade name Milled Fihani average fiber length 100 uLm), and as GB, commercially available glass beads (manufactured by Toshiba Herodin Co., Ltd.: trade name GB73) were used.
1. An average particle size of 30 gm) was used. The blending ratio of CF in the intermediate layer 2 is 20 parts by weight per 100 parts by weight of PEEK, and the blending ratio of GB in the surface layer 3 is as follows:
The amount was 10 parts by weight based on 100 parts by weight of PEEK. ] Each of the dies produced above was placed in a 40 mmφ extruder (extrusion capacity 20 kg/hr; equipped with a heating mechanism).
, and extruded nylon resin (nylon 6) through the die with a nozzle diameter of 3 m rrB in an amount of 15 kg.
/ hr, and pelletized by underwater granulation method. On the other hand, polypropylene (PP) resin (manufactured by Idemitsu Petrochemical Company) was extruded from the die with a nozzle diameter of 0.6 mm at a die setting temperature of 230°C. It was made into pellets using an underwater granulation method.

As a result, it was possible to perform granulation stably without any problems. Note that when the cross sections of the obtained nylon pellets and PP pellets were visually observed using a loupe with a magnification of 10 times, they were both well-shaped and spherical. In addition, the particle sizes of each particle were very uniform, and visual inspection revealed that the nozzle was not clogged.

(Comparative Example Ratios 1 and 2) Nylon was prepared in the same manner as in Examples 1 and 2, except that each of the commercially available dies used as the die body in Examples 1 and 2 was used as a die without providing a heat insulating layer. Underwater granulation into pellets and PP pellets was attempted.

As a result, in either case, it was not possible to obtain pellets with a clean cross-sectional shape, and moreover, the nozzle became clogged within a very short time, making granulation impossible.

[Brief explanation of drawings]

FIG. 1 is a partial sectional view showing a heat insulating layer portion of a die which is an example of the die of the present invention. ■...Heat insulation layer, ■...Dice body, l...Adhesive layer, 2...Intermediate layer, 3...Surface layer 3

Claims (1)

[Claims] (1) A die for a granulator, characterized in that the cutter side surface of the die is provided with a heat insulating layer containing a polar group-containing resin having a melting point of 250° C. or higher.