JP4424967B2 - Method for producing thermoplastic resin pellets containing additives - Google Patents

Description

  The present invention relates to a method for producing an additive-containing thermoplastic resin pellet by attaching an additive to the surface of the thermoplastic resin pellet.

A product made of a thermoplastic resin material has been conventionally molded by injection molding or the like. In this case, the pellets are conveyed into a high-temperature cylinder of an injection molding machine (hereinafter sometimes referred to as plasticization), and then the molten resin is injected, cooled, and released into molds processed into various product shapes. Product. In recent years, shortening of molding time has been demanded from an environmental and economic viewpoint.
Specifically, for example, the molding is performed with the temperature of the cylinder set higher than the conventional temperature and the temperature of the mold set lower than the conventional temperature. Or, molding using hot runners, recycling products. In addition, from the viewpoint of component integration, product shapes have become larger, thinner, and more complicated. However, even if the molding conditions are changed and the molding time is shortened as described above, the molding time will be longer than expected due to the lack of plasticization or unstable plasticization.

In the hot runner method and product recycling, the performance of the product obtained by thermal degradation of the resin is insufficient, or the appearance of the product is defective due to the generation of thermal decomposition components. In addition, the molten resin does not flow to the end of a product mold that is large, thin, or complicated (that is, the problem of insufficient fluidity), or the product does not release from the mold.
As a method for solving these problems, organic heat stabilizers such as hindered phenol compounds and organic phosphite compounds, and lubricants such as higher fatty acid metal salts, higher fatty acid amides and higher fatty acid esters have been used as thermoplastic resins. A technique for inclusion in pellets is used. In particular, it is well known in the art that a method of attaching an organic heat stabilizer or a lubricant to the surface of a thermoplastic resin pellet is used in order to improve plasticization, mold release, and thermal stability during molding as described above. Is the fact of

For example, there is a method in which a thermoplastic resin pellet, mineral oil, an additive, and the like are mixed using a tumbler or the like, and a lubricant is adhered to the pellet surface. However, in this method, it is difficult to make the additive uniformly adhere to the pellet surface, and the additive is easy to fall off, and the performance such as plasticization, mold release and thermal stability is lowered, or the dropped additive is removed from the molding machine. It causes the problem of deterioration of the working environment due to contamination and dust adhering to the hopper.
As a method for solving these problems, a method in which a part or all of the additive is melted and adhered to the pellet surface in a molten state, and then the additive is solidified and the additive is uniformly adhered to the pellet surface in a film form. Is used. As an apparatus for performing this method, for example, an apparatus that is a vertical chamber represented by a Henschel mixer and has a horizontal stirring device inside is used.

However, this method has an economical problem that it is difficult to deposit continuously on the apparatus and must be performed by a batch method. In addition, there is a problem that the pellets are partly powdered by the shearing of the stirring blade.
There is also an example in which a fluidized bed type apparatus is disclosed (for example, see Patent Document 1). However, this apparatus has an economical problem that a large blower is required because a strong blow is required to flow the pellets. In addition, since the additive melted by the cooperative blowing is easily solidified before adhering to the pellet in the form of a film, there arises a problem that an additive having a particularly high melting point and softening point cannot be adhered.

In addition, there is an example in which a method of forming a lubricant film on the pellet surface by using a pellet and a lubricant in combination and mixing at a temperature lower than the melting point of the lubricant to generate a mutual collision and a shearing force is also disclosed (for example, Patent Document 2). However, this method has problems such as insufficient adhesion and the inability to attach an additive having a high melting point and softening point.
JP-A-8-239482 Japanese National Patent Publication No. 8-500549

  In the present invention, the additive is uniformly coated on the surface of the thermoplastic resin pellet so that the additive does not fall off in various moldings such as transfer or injection molding using a newer and the like. An object of the present invention is to provide a method for producing a thermoplastic resin pellet containing an additive excellent in performance such as plasticization, releasability and thermal stability.

As a result of intensive studies to solve the above-described problems of the present invention, the present inventors have, as a result, a facility and additive for heating and melting and spraying an additive to a stirrer provided with a screw that rotates and revolves along the inner wall surface of the conical casing. via the use of an apparatus having a facility of adding powder, by Rukoto is coated with the additive to the thermoplastic resin pellet surface into a film, it found that can solve the above problems, and have completed the present invention.

That is, the present invention
1. After the addition of the additive by heating and melt spraying, the apparatus is equipped with equipment for heating and spraying the additive to the stirrer equipped with a screw that rotates and revolves along the conical casing, and equipment for adding powder to the additive. Additive powder is added, and the additive solid powder powder added to the surface of the thermoplastic resin pellets does not float, and the additive is characterized by uniformly coating the heated and sprayed additive into a film. A method for producing thermoplastic resin pellets,
2. The thermoplastic resin is at least one selected from polyamide resin, polyphenylene ether resin, polyoxymethylene resin, aromatic polyester resin, aromatic polycarbonate resin, polyphenylene sulfide resin, polyolefin resin, styrene resin, acrylic resin, and rubber. The method for producing a thermoplastic resin pellet according to the above 1, wherein the pellet is a seed pellet,
3. 3. The additive according to 1 or 2 above, wherein the additive is at least one compound selected from a hindered phenol compound, a hindered amine compound, an organic phosphite compound, a higher fatty acid metal salt, a higher fatty acid amide, and a higher fatty acid ester. Manufacturing method of thermoplastic resin pellets,
It is.

  By the production method of the present invention, there is little dropout of additives in various moldings such as transfer or injection molding using a pneumatic or the like, and the performance such as plasticizing property, releasability and thermal stability in various moldings and the like. It is possible to obtain a thermoplastic resin pellet to which an additive having an excellent feature that there is little variation is attached.

Hereinafter, the present invention will be described in detail.
The thermoplastic resin preferably used in the present invention is, for example, polyamide resin, polyphenylene ether resin, polyoxymethylene resin, aromatic polyester resin, aromatic polycarbonate resin, polyphenylene sulfide resin, polyolefin resin, styrene resin, acrylic resin, rubber, Or from condensation resins such as aramid and polyimide, polyether resins such as polysulfone, polyethersulfone, and polyetherketone, and halogen-containing vinyl compound resins such as polyvinyl chloride, polyvinylidene chloride, polyvinyl fluoride, and polyvinylidene fluoride. Mention may be made of at least one resin selected.
Among them, at least one resin selected from polyamide resin, polyphenylene ether resin, polyoxymethylene resin, aromatic polyester resin, aromatic polycarbonate resin, polyphenylene sulfide resin, polyolefin resin, styrene resin, acrylic resin, rubber, etc. is used. Is preferred.

In addition, an antistatic agent such as polyalkylene ethers conventionally used may be spread on the surface of the resin pellets of the present invention to the extent that the object of the present invention is not impaired.
Examples of the additive of the present invention include organic heat stabilizers such as hindered phenol compounds, hindered amine compounds, organic phosphite compounds, hindered amine compounds, and lubricants such as higher fatty acid metal salts, higher fatty acid amides, and higher fatty acid esters. . Examples of the higher fatty acid metal salt include calcium stearate, zinc stearate, aluminum monostearate, aluminum distearate, aluminum tristearate, and calcium montanate.

  Examples of higher fatty acid amides include ethylene bisstearyl amide, erucic acid amide, N-stearyl erucic acid amide, N-palmityl erucic acid amide, N-stearyl stearyl amide, and mixtures thereof. As the higher fatty acid ester, stearyl stearate can be exemplified. These additives may be used alone or in combination of two or more. In addition, the additives of the present invention include additives conventionally used to the extent that the object of the present invention is not impaired, such as pigments and dyes, flame retardants, fluorescent bleaching agents, plasticizers, organic antioxidants, heat Stabilizers, UV absorbers, nucleating agents, rubber, and reinforcing agents may be blended.

The stirrer provided with a screw that rotates and revolves along the inner wall surface of the conical casing of the present invention includes a device that heats and melts the additive. An apparatus for heating and spraying the additive also has a heating apparatus. This makes it possible to spray various additives having a melting point or softening point from a low temperature to a high temperature in a liquid or molten state. Furthermore, the stirrer of the present invention is also provided with a device for adding additives in powder form. Thereby, various additives having high solution viscosity or melt viscosity can be adhered.
There is no particular restriction on the order of the above-mentioned hot melt spray addition and powder addition method. However, in order to improve the high temperature formability by attaching a higher melting point additive to the outside of the pellet, It is desirable to add them in the order of body addition.

By using the apparatus of the present invention, the target additive is sprayed in a liquid or molten state from the additive heat-melting spray apparatus provided on the thermoplastic resin pellets carried into the apparatus from the carry-in entrance, and further powdered. The target additive is spread in powder form from the body addition device. The pellet sprayed and spread with the additive is uniformly and efficiently stirred by a screw that rotates and revolves along the inner wall surface of the conical casing, so that the additive can uniformly adhere to the pellet surface. The pellets introduced into the stirring device from the carry-in port can be continuously carried out from the carry-out port after the additive is contained in the pellets by the above method. In addition, the batch method, that is, a method in which pellets are put into a stirrer and the inlet and outlet are closed, and then the additive is sprayed, spread and stirred, and the whole amount of pellets is carried out, the additive is added to the pellet surface. It is to attach.

  In the present invention, in order to adhere the additive to the pellet surface uniformly and efficiently, the temperature in the stirrer can be changed according to the additive used. In addition, an inert gas such as nitrogen may be circulated in the stirrer to suppress a decrease in the color tone of the pellets. Examples of the method of changing the temperature in the stirrer variously include a method of circulating and heating a heated inert gas, a method of heating with a heater, a method of circulating a heating medium provided in a jacket and controlling the temperature. . As a stirrer provided with a squeeze that rotates and revolves along the inner wall surface of the conical casing of the present invention, a Nauta mixer manufactured by Hosokawa Micron Corporation can be exemplified.

  The surface of the thermoplastic resin pellet obtained by the method of the present invention is characterized in that the additive adheres firmly and uniformly in the form of a film. The form of “strongly and uniformly in the form of a film” has such a form that the varnish is essentially uniformly applied to the pellet surface. This form is completely different from the pellet surface obtained by, for example, blending thermoplastic resin pellets, mineral oil, additives, and the like using a blender or the like and attaching a lubricant to the pellet surface.

  This difference in form can be confirmed by observing the pellet surface with an optical microscope or a scanning electron microscope (SEM). To describe specific differences in the form of the pellet surface, the pellet surface obtained by the production method of the present invention is applied uniformly and continuously so that the boundary of the additive cannot be identified as described above, The conventional blending method is greatly different in that the additive is granular, non-uniform, and discontinuously attached. Therefore, the pellets of the present invention have a strong and uniform film-like additive, so that there is little dropout of the additive in various moldings such as transfer or injection molding using a newer, etc. It has excellent characteristics such as plasticizing properties, mold release properties, thermal stability, etc. in molding, and few variations thereof.

  The thermoplastic resin pellets obtained by the production method of the present invention are known molding methods such as press molding, injection molding, gas assist injection molding, welding molding, extrusion molding, blow molding, film molding, hollow molding, multilayer molding, Even if a generally known plastic molding method such as melt spinning is used, molding can be performed satisfactorily. Especially, it is excellent in injection moldability.

  EXAMPLES Hereinafter, although an Example demonstrates this invention still in detail, this invention is not restrict | limited to a following example, unless the summary is exceeded. In addition, the physical property evaluation described in the following examples and comparative examples was performed as follows.

[ Reference Example 1]
As a stirrer equipped with a screw that rotates and revolves along the inner wall surface of the conical casing, a Nauta mixer (Hosokawa Micron Corporation) was used. Steam was circulated through the jacket, and the jacket temperature was kept at 80 ° C. The stirring device was equipped with an additive spraying device that can be heated to 180 ° C. As an additive, aluminum distearate (melting point: about 150 ° C.) was used. In the apparatus, polyamide pellets (Leona 1300 manufactured by Asahi Kasei Co., Ltd.) were charged, sealed, and stirred for a while. At this time, the pellet temperature was about 60 ° C. Thereafter, a predetermined amount of aluminum melted distearate was sprayed, and after about 1 minute, the pellets were discharged. Little dust was observed inside the pellets and jacket. Further, when the obtained pellet surface was observed with a scanning electron micrograph, it was observed that the pellet surface was firmly and uniformly attached to the film.

[ Reference Example 2]
The same procedure as in Example 1 was performed except that a mixture of aluminum distearate and N-stearyl erucamide (melting point: about 70 ° C.) in a weight ratio of 1/1 was used as an additive. When the obtained pellet surface was observed with a scanning electron micrograph, it was observed that the pellet surface was firmly and uniformly attached to the film.

[Example 3]
As a stirrer equipped with a screw that rotates and revolves along the inner wall surface of the conical casing, a Nauta mixer (Hosokawa Micron Corporation) was used. Steam was circulated through the jacket, and the jacket temperature was kept at 80 ° C. Further, the stirring device was equipped with an additive spraying device that can be heated to 180 ° C. and a device that can add powder of the additive. As additives, N-stearylerucamide (containing N-palmitylerucamide, melting point: about 70 ° C.) and aluminum distearate were used. Polyamide pellets (Leona 1300 manufactured by Asahi Kasei Co., Ltd.) on which polyethylene glycol (molecular weight 400) as an antistatic agent was spread were put in the apparatus, sealed, and stirred for a while. At this time, the pellet temperature was about 60 ° C.
Thereafter, a predetermined amount of N-stearyl erucamide heated and melted at 120 ° C. was sprayed. Immediately after that, a predetermined amount of aluminum distearate powder was added, and after about 3 minutes, the pellets were discharged. Little dust was observed inside the pellets and jacket. Moreover, when the obtained pellet surface was observed with the scanning electron micrograph, it was observed that the solid powder was uniformly attached in the form of a film without being raised.

[Example 4]
As an additive to be added as a powder, aluminum distearate, Irganox 1098 (Ciba Specialty Chemicals Co., Ltd. N, N'-hexane-1,6-diylbis [3- (3,5-di-tert-butyl-4) -Hydroxyphenyl) propioamide]) in the same manner as in Example 3 except that a weight ratio of 1/1 was used. Little dust was observed inside the pellets and jacket. Further, when the obtained pellet surface was observed with a scanning electron micrograph, it was observed that the solid powder was uniformly attached in the form of a film without being raised.

  The method of the present invention can be suitably used for uniformly attaching an additive to the surface of a thermoplastic resin pellet.

Claims (3)

After the addition of the additive by heating and melt spraying, the apparatus is equipped with equipment for heating and spraying the additive to the stirrer equipped with a screw that rotates and revolves along the conical casing, and equipment for adding powder to the additive. Additive powder is added, and the additive solid powder powder added to the surface of the thermoplastic resin pellets does not float, and the additive is characterized by uniformly coating the heated and sprayed additive into a film. The manufacturing method of the thermoplastic resin pellet to contain.   The thermoplastic resin is at least one selected from polyamide resin, polyphenylene ether resin, polyoxymethylene resin, aromatic polyester resin, aromatic polycarbonate resin, polyphenylene sulfide resin, polyolefin resin, styrene resin, acrylic resin, and rubber. It is a seed pellet, The manufacturing method of the thermoplastic resin pellet of Claim 1 characterized by the above-mentioned.   3. The additive according to claim 1, wherein the additive is at least one compound selected from a hindered phenol compound, a hindered amine compound, an organic phosphite compound, a higher fatty acid metal salt, a higher fatty acid amide, and a higher fatty acid ester. The manufacturing method of the thermoplastic resin pellet of description.