JP2999546B2 - Method of kneading thermoplastic resin - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for processing a thermoplastic resin. More specifically, the present invention relates to an improved kneading method capable of adjusting the flow characteristics of a thermoplastic resin by a simple method.

[Conventional technology]

In recent years, the range of applications of thermoplastic resin molded products has been in the automotive field, electric / electronic field, mechanical parts, office equipment parts, aviation /
It is diversified into parts and consumption materials in the space field, etc., and is used for advanced applications. with this,
The performance required for molded articles of thermoplastic resin is diversified and at the same time extremely strict performance is required.

On the other hand, in order to supply molded articles satisfying these requirements, many proposals have been made regarding manufacturing techniques and materials.

The method for producing a molded product is mainly melt molding such as injection molding, blow molding, and press molding. That is, the thermoplastic resin material is formed into various target molded products in a molten state. Therefore, the properties of the thermoplastic resin in the molten state, and sometimes the flow properties in the molten state, are extremely important factors, and in order to supply a proper molded product, the thermoplastic resin having the proper flow properties is required. Supply is essential.

Generally, the flow characteristics of a thermoplastic resin, before kneading,
It is uniquely determined by the raw material resin material and the additive material such as the plasticizer.

In order to provide thermoplastic resin materials having different flow characteristics, a method is employed in which, during kneading, raw resin materials having different characteristics are appropriately selected and blended with additive materials. That is, the supply of thermoplastic resins having different flow characteristics has been achieved only after extensive research and studies have been made, such as production or selection of appropriate raw material resin materials and selection of additive materials.

In addition, the function of the vent suction in the melt-kneading process by the conventional vent-type extruder is to discharge a gas composed of water and volatile components evaporating in the extruder from a material such as a resin material or an additive to the outside of the extruder (degassing). In the role of
The purpose is to eliminate adverse effects on products such as degradation of resin materials such as hydrolysis and foaming caused by gas. Therefore, it is general to remove the moisture and volatile components by deaeration by maximizing the suction of the vent, and there is no melt-kneading method for adjusting the suction pressure as in the present invention.

[Problems to be solved by the invention]

An object of the present invention is to provide a thermoplastic resin material having adjusted flow characteristics without extensive research and study on the physical properties of various resins as in the related art. That is, there is a need to supply thermoplastic resin materials having different flow characteristics with the same raw material resin material and additive material mixture without changing the raw material resin material and additive material mixture.

[Means for solving the problem]

That is, the present invention relates to two or more types of thermoplastic polyesters, polyarylates, aliphatic polyamides, aromatic polyamides or mixtures thereof, or copolymers of these with other copolymerizable monomers. A degassing mechanism (vent) is applied to a mixture of a thermoplastic resin or a mixture of at least one thermoplastic resin selected from the above group and at least one material of an additive, a colorant, an inorganic filler, and a fiber reinforced material. Using an extruder, melt-kneading while maintaining the degree of vacuum of the degassing mechanism in the range of -70 mmHg to 0 mmHg,
An object of the present invention is to provide a method for kneading a thermoplastic resin, which comprises adjusting a melt flow rate of the thermoplastic resin after melt-kneading.

Further, the present invention provides a method for kneading the above thermoplastic resin whose material is glass fiber.

Further, the present invention uses the extruder having a plurality of degassing mechanisms, and feeds the glass fiber from the middle between the first vent (the degassing mechanism closest to the resin supply side) and the next vent. An object of the present invention is to provide a method for kneading a plastic resin.

 Hereinafter, the present invention will be described in more detail.

The present invention uses an extruder with a degassing mechanism in a kneading operation in which thermoplastic resins and / or additives, a coloring agent, an inorganic filler, and a fiber-reinforced material such as glass fiber are melt-mixed by a kneader. The degree of decompression of the degassing mechanism during the melt-kneading process is adjusted in the range of -700 mmHg to 0 mmHg,
This is a method for controlling the flow characteristics of the resin after the melt-kneading process.

The thermoplastic resin material used in the present invention is a thermoplastic polyester, a polyarylate, an aliphatic polyamide, an aromatic polyamide, a mixture thereof, or a copolymer thereof with a copolymerizable monomer.

At the time of kneading, various additives (for example, stabilizers, lubricants, antioxidants, ultraviolet absorbers, plasticizers, nucleating agents,
In general, a melt-kneading process is performed by adding a flame retardant, an improver such as impact strength, etc.), a colorant, an inorganic filler, and a fiber reinforced material such as glass fiber.

The kneader used in the present invention may have any deaeration mechanism. Generally, a vent type extruder is used.
In the following description, an extruder having a degassing mechanism will be described as a vented extruder. The vented extruder may be a single screw extruder or a twin screw (or multi-screw) extruder,
The vent port can be provided at one or more places, for example, two or three places.

An important point in the present invention is to adjust the degassing mechanism, for example, the degree of pressure reduction of the vent. The kneading operation is most effective when the degree of depressurization of the vent (suction pressure) is in the range of -700 mmHg to 0 mmHg, and an appropriate vent suction pressure is set in order to obtain a resin having a desired fluidity. Here, the degree of pressure reduction or suction pressure refers to the degree of pressure reduction from atmospheric pressure (760 mmHg A).

That is, the present invention is characterized in that, contrary to the original purpose of the vent extruder, melt kneading is performed while suppressing the effect of vent suction.

More specifically, the present inventors have found that the flow characteristics of the melt-kneaded thermoplastic resin strongly depend on the suction pressure of the vent during the melt-kneading process, and have reached the present invention. The inventor invented that the lower the vent suction pressure, the lower the fluidity, and the higher the vent suction pressure, the higher the fluidity.It is surprisingly good to control the fluidity by melt-kneading using a fixed resin raw material. Invented what can be done.

That is, in order to supply a thermoplastic resin material having the desired flow characteristics, the purpose can be achieved very easily by adjusting the vent suction pressure without changing the resin raw material.

In addition, these effects, specific thermoplastic resin, namely,
It has been found to be particularly effective in thermoplastic polyesters, polyarylates, aliphatic polyamides, aromatic polyamides or mixtures thereof, or copolymers thereof with other copolymerizable monomers.

[Action]

These phenomena are presumed to have a remarkable effect when using thermoplastic resin raw materials that are susceptible to hydrolysis. If the degree of depressurization of the vent suction is changed (when the pressure is increased), the molten resin in the extruder can be changed. It is thought that the content of water and the like contained in the water increases to promote hydrolysis and the like, and as a result, the fluidity increases. That is, since the equilibrium relationship can be changed by adjusting the vent suction pressure for the amount of water contained in the molten resin in a gas-liquid equilibrium state in the extruder, deterioration (change in fluidity) due to hydrolysis or the like is controlled. It is estimated to be.

〔Example〕

Next, the present invention will be described in more detail with reference to examples.

Example 1 Polyethylene terephthalate [PBK-, manufactured by Kanebo Co., Ltd.]
1) was melt-kneaded using a vented single-screw extruder to produce granulated pellets. The vent suction pressure during the melt-kneading process was changed from -700 mmHg to 0 mmHg, and the melt flow rate of the obtained granulated pellets was measured by the flowability test method for thermoplastics (JIS K7210). The measurement was performed at a test temperature of 280 ° C. and a test load of 2.16 kg. Table 1 shows the value of the melt flow rate at each vent pressure. There is a very good correlation between the vent suction pressure and the melt flow rate, and it can be seen that the melt flow rate (flow characteristics) can be controlled by the vent suction pressure.

Example 2 70 parts by weight of polyethylene terephthalate (same as in Example 1) and 30 parts by weight of glass fiber (chopped strand having a fiber diameter of 13 μm and a fiber length of 3 mm) were melt-kneaded in the same manner as in Example 1, Granulated pellets were made. Further, the melt flow rate of the granulated pellet was measured in the same manner as in Example 1. Table 1 shows the melt flow rate at each vent suction pressure. As in Example 1, the vent suction pressure and the melt flow rate have a very good correlation, indicating that the flow characteristics can be controlled by the vent suction pressure.

Example 3 The same material as in Example 2 was melt-kneaded using a twin-screw extruder having two vents to produce granulated pellets. The glass fiber was fed from the middle between the first vent (vent on the resin supply side) and the second vent (vent on the granulation die side). The suction pressure of the first vent is -700mmH
The suction pressure of the second vent was kept constant at -700 mmHg by changing from g to 0 mmHg. In the same manner as in Example 1,
The melt flow rate of the granulated pellet was measured, and the melt flow rate at each vent suction pressure is shown in Table 2. There is a good correlation between the suction pressure of the first vent and the melt flow rate, which indicates that the flow characteristics can be controlled.

Example 4 The same material as in Example 3 was melt-kneaded in the same manner as in Example 3 to produce granulated pellets. At this time the first
The suction pressure of the vent was independently changed from -700 mmHg to 0 mmHg, and the suction pressure of the second vent was independently changed to -600 mmHg.

The melt flow rate of the granulated pellet was measured in the same manner as in Example 1. Table 2 shows the melt flow rate at each suction pressure. From this result, it is understood that a resin having any flow characteristics can be obtained from the combination of the suction pressures of the first vent and the second vent.

Example 5 70 parts by weight of polyamide (KR4411 manufactured by BASF Japan) and 30 parts by weight of glass fiber (chopped strand having a fiber diameter of 13 μm and a fiber length of 3 mm) were melt-kneaded in the same manner as in Example 3 to produce a mixture. A pellet was prepared. At this time, the suction pressure of the first vent was changed from -700 mmHg to 0 mmHg,
The suction pressure of the vent was also changed from -70 mmHg to 0 mmHg, and the flow characteristics of the granulated pellets were measured in the same manner as in Example 1. However, the measurement conditions were a test temperature of 275 ° C. and a test load of 2.16 kg. Table 3 shows the melt flow rate at each vent suction pressure. There is a very good correlation between the vent suction pressure and the melt flow rate, indicating that the flow characteristics can be controlled by the vent suction pressure.

Example 6 70 parts by weight of polycarbonate (manufactured by Mitsubishi Gas Chemical Company, S-2000) and 30 parts by weight of crow fiber (chopped strand having a fiber diameter of 13 μm and a fiber length of 3 mm) were melt-kneaded in the same manner as in Example 3. Thus, granulated pellets were prepared. At this time, the suction pressure of the first vent was changed from -700 mmHg to 0 mmHg, and the suction pressure of the second vent was also changed from -700 mmHg to 0 mmHg. The melt flow rate of the granulated pellet was measured in the same manner as in Example 1. Table 4 shows the value of the melt flow rate at each vent suction pressure. There is a very good correlation between the vent suction pressure and the melt flow rate, indicating that the flow characteristics can be controlled by the vent suction pressure.

[Effects of the Invention] The present invention can adjust the flow characteristics of the resin by adjusting the degree of vacuum during melt-kneading by the extruder provided with the degassing mechanism as described above, so that various molding conditions Can be provided by a relatively simple method.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B29C 47/00-47/96

Claims (3)

(57) [Claims] 1. A thermoplastic polyester, a polyarylate,
Aliphatic polyamides, aromatic polyamides or mixtures thereof, or mixtures of two or more thermoplastic resins selected from the group consisting of copolymers of these with other copolymerizable monomers, or selected from the above group The mixture of at least one kind of thermoplastic resin and at least one kind of additives, colorants, inorganic fillers and fiber-reinforced materials is depressurized by an extruder equipped with a degassing mechanism (vent). Degree-
A method for kneading a thermoplastic resin, comprising melt-kneading while maintaining the temperature in the range of 700 mmHg to 0 mmHg, and adjusting the melt flow rate of the thermoplastic resin after the melt-kneading. 2. The method for kneading a thermoplastic resin according to claim 1, wherein the material is glass fiber. 3. The method according to claim 1, wherein an extruder having a plurality of degassing mechanisms is used, and the glass fiber is fed from between the first vent (the degassing mechanism closest to the resin supply side) and the next vent. 3. A method for kneading a thermoplastic resin according to claim 2.