JP4357930B2 - Method for producing thermoplastic resin pellets containing additives - Google Patents

Description

  The present invention relates to a method for producing a thermoplastic resin pellet containing an additive by attaching the 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, with this method, it is difficult to make the additive uniformly adhere to the pellet surface, and the additive tends to fall off, resulting in a decrease in performance such as plasticization, mold release, thermal stability, etc. It causes the problem of deterioration of work 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 strong air 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 having excellent performance such as plasticization, releasability and thermal stability.

As a result of intensive studies to solve the above-mentioned problems of the present invention, the present inventors have equipped a horizontal chamber type stirrer equipped with a skid type shovel blade with equipment for heating and spraying the additive and equipment for adding powder. The present inventors have found that the above-mentioned problems can be solved by attaching an additive to the surface of the thermoplastic resin pellet using the above, and have completed the present invention.

That is, the present invention
1. Using an apparatus equipped with a horizontal chamber type stirrer equipped with a skive type shovel blade and equipment for heating and spraying the additive and equipment for adding powder, the heat melting and spraying of the additive and powder addition are performed. A production method for obtaining a thermoplastic resin pellet containing an additive by attaching an additive to the surface of the plastic resin pellet.
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 production method according to 1 above, which 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,
It is.
4. The method according to any one of 1 to 3 above, wherein the additive is added in the order of heat-melt spray addition and powder addition.
5). 5. The production method according to 4 above, wherein the additive to be powdered has a higher melting point than the additive to be added by hot melt spraying.

  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 condensation resins such as aramid and polyimide, polyether resins such as polysulfone, polyethersulfone and polyetherketone, polyvinyl chloride,
Examples thereof include at least one resin selected from halogen-containing vinyl compound resins such as polyvinylidene chloride, polyvinyl fluoride, and polyvinylidene fluoride.
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, rubbers, and reinforcing agents may be blended.

The horizontal chamber type stirrer provided with the skid type shovel blade of the present invention includes a device for heating and melting and spraying the additive. The apparatus for heating and melting and spraying the additive also has a heating apparatus. Thereby, various additives having a melting point or softening point from a low temperature to a high temperature can be heated and melt sprayed. 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. In addition, there is no particular restriction on the order of the above-mentioned hot melt spray addition and powder addition method, but in order to adhere a higher melting point additive to the outside of the pellet and enhance high temperature formability, the heat melt spray addition, powder It is desirable to add in the order of addition.

By using the apparatus of the present invention, the target additive is sprayed in a liquid or molten state from the additive heating melt spraying apparatus provided on the thermoplastic resin pellets carried into the chamber from the carry-in entrance, and further powdered The target additive is spread in powder form from the addition device. The pellet obtained by spraying and spreading the additive with heat melting can be uniformly and efficiently stirred using a skid type shovel blade to adhere the additive to the surface of the pellet. The pellets to which the additive has been adhered are continuously carried out from the carry-out port.
In addition, the batch method, that is, a method in which pellets are charged into a horizontal chamber as needed, the inlet and outlet of the chamber are closed, and then the additive is heated and melted sprayed, spread, and stirred to carry out the entire pellet amount. The additive can be attached to the pellet surface. In the present invention, in order to adhere the additive uniformly and efficiently to the pellet surface, the temperature in the horizontal chamber can be changed according to the additive used.

  In addition, an inert gas such as nitrogen may be circulated in the chamber to suppress a decrease in the color tone of the pellet. Examples of the method for changing the temperature of the horizontal chamber in various ways include a method in which heated inert gas is circulated and heated, a method in which heating is performed with a heater, a method in which a jacket is provided in a jacket and a heat medium is circulated to control temperature. . Examples of the horizontal chamber type agitation provided with the skid type shovel blade rotating in the vertical direction of the present invention include a proshear mixer (batch type or continuous type) manufactured by Taiheiyo Kiko Co., Ltd.

  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 and additives using a blender or the like to attach 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]
A proshear mixer (WB-75 type (batch type) manufactured by Taiheiyo Kiko Co., Ltd.) was used as a horizontal chamber type stirrer equipped with ski type shovel blades. Steam was circulated through the jacket, and the jacket temperature was kept at 80 ° C. The chamber was also equipped with an additive spraying device that could be heated to 180 ° C. As an additive, aluminum distearate (melting point: about 150 ° C.) was used. Polyamide pellets (Leona 1300 manufactured by Asahi Kasei Co., Ltd.) were put into the chamber, 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-stearylerucamide (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]
A proshear mixer (WA-75 type (continuous type) manufactured by Taiheiyo Kiko Co., Ltd.) was used as a horizontal chamber type stirrer equipped with ski type shovel blades. Further, the chamber was equipped with an additive spraying apparatus that can be heated to 180 ° C. and an apparatus that can add powder of the additive. As additives, N-stearyl erucamide (containing N-palmitylerucamide, melting point: about 70 ° C.) and aluminum distearate were used. Polyamide pellets (Leona 1300 manufactured by Asahi Kasei Co., Ltd.) are continuously charged into the chamber, and a predetermined amount of a drop of polyethylene glycol (molecular weight 400) as an antistatic agent is added, and N-stearyl is heated and melted at 120 ° C. A predetermined amount of erucamide was sprayed, and immediately after that, a predetermined amount of aluminum distearate powder was added, and the pellets were discharged at a discharge rate of about 1 ton / hr. 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.

[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 (5)

Using an apparatus equipped with a horizontal chamber type stirrer equipped with a skive type shovel blade and equipment for heating and spraying the additive and equipment for adding powder, the heat melting and spraying of the additive and powder addition are performed. A production method for obtaining a thermoplastic resin pellet containing an additive by attaching an additive to the surface of the plastic resin pellet. 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 production method according to claim 1, which is a seed pellet. Additives, hindered phenol compounds, hindered amine compounds, organic phosphite compounds, higher fatty acid metal salts, higher fatty acid amides, that to claim 1 or 2, characterized in that at least one compound selected from higher fatty acid esters The manufacturing method as described. The manufacturing method according to any one of claims 1 to 3 , wherein the additive is added in the order of hot melt spray addition and powder addition. The manufacturing method according to claim 4, wherein the additive to be added with a powder has a higher melting point than the additive to be added by heating and melt spraying.