JP2011201048A - Injection molding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an injection molding method preventing blocking of materials in an injection molding device, as well as performance deterioration of resin, by directly melting the materials in the injection molding device without using a kneading extruder.SOLUTION: The injection molding method for supplying materials, the materials including at least a base resin 50, an organic compound 52 which is a liquid at ordinary temperature and an inorganic filler 54, to the injection molding device to knead and melt the materials has a step of mixing the materials prior to supply to the injection molding device. In this step, the organic compound 52 is mixed to the base resin 50 first, and the inorganic filler 54 and other components 58 are then added and mixed therewith.

Description

  The present invention relates to an injection molding method, and more specifically, at least a base resin, an organic compound that is solid at room temperature and has a melting point of 24 to 80 ° C., and an inorganic filler, and the material is injected. The present invention relates to an injection molding method for supplying to a molding apparatus, kneading and melting.

  Conventionally, petroleum-based resins have been mainly used as resin molding materials for injection molding, but problems such as air pollution, global warming, and ozone layer destruction have become obvious. Attempts have been made to build a society. As one of them, conversion from a petroleum resin molding material to a biological plant resin molding material has been attempted.

  Plant-based resin molding materials include so-called biomass resins (also referred to as biomass plastics or bioplastics), and attempts have been made to produce various products using these as molding materials.

  Typical examples of biomass resins include polylactic acid (also referred to as polylactic acid resin or PLA) and cellulosic resins. These biomass resins can be expected to eliminate carbon dioxide uptake and generation in the global environment, and this idea is called carbon neutral.

  However, when a molded product is manufactured by injection molding using a biomass resin as a molding material, the low heat resistance of the biomass resin becomes a problem. Biomass resin has a smaller difference between the temperature at which it can be melted by heat and it can easily flow, and the decomposition temperature of the resin, compared to petroleum-based resin, so it can be used in injection molding and pre-processing processes. There is a problem that the setting range is limited. For example, when the biomass resin and the additive are kneaded with a kneader and pelletized in the pretreatment before being supplied to the injection molding apparatus, if the resin is exposed to high heat for a long time, the resin is likely to be colored or reduced in molecular weight. In particular, in order to make the biomass resin flame-retardant, it is necessary to knead a large amount of flame retardant into the biomass resin, and it is preferable to pelletize the biomass resin and the difficult agent in advance and then supply them to the injection molding apparatus. However, there is a problem that the biomass resin is decomposed during the heat processing in the kneader and the strength of the molded product is lowered.

  In addition, the biomass resin has a brittle property in strength and has a problem that it is difficult to obtain strength. In particular, since the biomass resin needs to incorporate a large amount of flame retardant as described above, it becomes increasingly brittle in strength. For this reason, when the biomass resin is kneaded with a flame retardant to ensure a low viscosity, it is necessary to add a reinforcing agent to increase the strength.

  As a method for increasing the strength of biomass resin, it can also be achieved by mixing petroleum resin, but this is not an essential solution for reducing environmental burden. As another method, there is a method of adding inorganic fibers such as glass fibers or petroleum-based organic fibers, and this is preferable because strength can be obtained without significantly reducing the plantiness of the molded body. As yet another method, there is a method in which natural molding materials such as bamboo and kenaf fibers are added as a fiber, and the fiber portion can be replaced with a carbon neutral material.

  Thus, in order to use biomass resin as a molding material for injection molding, it is common to add additives such as flame retardants and fibers. And considering the low heat resistance of the biomass resin, the biomass resin and the additive are not directly pretreated for kneading and mixing and pelletized, and the biomass resin and additive are directly fed into the injection molding apparatus. It is preferable for the quality of the molded product to adopt the direct injection molding method.

  In an injection molding device, pellets filled from a hopper are formed into a fluid which is melted and kneaded in a heating cylinder by a screw and an electric heater, and this fluid is filled into a mold at high pressure from a nozzle and solidified in the mold. It is molded into a molded product.

  Here, as a prior art, it is widely known that pellets are charged into a material inlet of an injection molding apparatus by a compound method or a master batch method. For example, in Patent Document 1, a heat-resistant polylactic acid resin and an impact-resistant polylactic acid resin are previously blended with a kneading extruder to form pellets, and the pellets are put into a material inlet of an injection molding apparatus. A master batch method is disclosed.

  Similarly, Patent Document 2 describes a material input port of an injection molding apparatus for the purpose of preventing heat deterioration of a resin material, preventing breakage of glass fibers, etc., and achieving advantages (quality improvement and cost reduction) due to process reduction. A “direct molding method” in which a material such as a resin is directly input has been proposed.

JP 2008-201863 A Japanese Patent Laid-Open No. 10-316832

  However, Patent Document 1 requires a step of kneading a material other than a resin into the resin to form a pellet, which increases the heat history of the resin and deteriorates the performance of the resin.

  Further, Patent Document 2 is not a molding method in which all of the material is directly supplied to the material input port of the injection molding apparatus, and molding is performed without kneading as much as possible components that are detrimental to maintaining the physical properties of the glass fiber and making it uniform in compounding. It was used only to do. Therefore, when a base resin such as polylactic acid with low heat resistance is blended with a kneading extruder and all components of the additive are directly fed into the material inlet of the injection molding apparatus without being pelletized, a component having a melting point of 80 ° C. or less Is melted by heat from the heating cylinder of the injection molding machine, etc. and adheres to the inlet port, obstructing the material supply, or being compressed by the weight of the material at the inlet port, blocking occurs and the material is There was a drawback that it could not be supplied stably.

  The present invention has been made in view of such circumstances, and provides an injection molding method capable of preventing the occurrence of material blocking in the injection molding apparatus without deteriorating the performance of the resin. With the goal.

  In order to achieve the above object, the present invention uses at least a base resin, an organic compound that is liquid at room temperature, and an inorganic filler, and supplies the material to an injection molding apparatus to knead and melt. A method comprising the steps of mixing the material before feeding it to an injection molding device, wherein the organic compound is first mixed with the base resin, and then the inorganic filler and other components. An injection molding method characterized by adding and mixing. In this case, it is more preferable that the organic compound is heated and then mixed with the base resin.

  In order to achieve the above object, the present invention uses at least a base resin, an organic compound that is solid at room temperature and has a melting point of 24 to 80 ° C., and an inorganic filler, and injects the material. An injection molding method for supplying to a molding apparatus, kneading and melting, comprising a step of mixing before supplying the material to the injection molding apparatus, in which the organic compound is heated to melt, An injection molding method is provided, wherein the molten organic compound is first mixed with a base resin, and then the inorganic filler and other components are added and mixed.

  Furthermore, in order to achieve the above object, the present invention uses at least a base resin, an organic compound that is liquid at room temperature, and an inorganic filler, and supplies the material to an injection molding apparatus to knead and melt. An injection molding method comprising a step of mixing the material before supplying the material to an injection molding device, wherein the organic compound is first mixed with the inorganic filler, and then the base resin and the others are mixed. An injection molding method is provided, wherein the components are added and mixed.

  In order to prevent the heat history of the resin from increasing and the performance of the resin from deteriorating, in the present invention, the material is directly supplied to the material inlet of the injection molding apparatus without being pelletized by the kneading extruder.

  In order to prevent the material from blocking the injection molding apparatus, it is conceivable to reduce the cohesive force between the materials or to reduce the frictional force between the material and the supply / conveyance passage. In order to realize them, it is generally considered to add an anti-aggregation agent such as silica or a lubricant, but there is a concern that the physical properties of the resin may be deteriorated. Further, the addition of an anti-aggregating agent or a lubricant increases the cost.

  Therefore, in the present invention, when the material is directly supplied to the material inlet of the injection molding apparatus, when mixing the material components, it adheres to the hopper wall and bridges or blocks, or adheres to the groove between the flights of the screw. The organic compound, which is a component that easily adheres to the material that cannot be transported, is first mixed with the base resin, and then coated with an inorganic filler or other component that is difficult to adhere to. did. If the organic compound is solid at room temperature, the organic compound is heated and melted, then mixed with the base resin first, and then coated with an inorganic filler, which is a component that is difficult to adhere to. To do. Even if the organic compound, which is a component that easily adheres, is liquid at room temperature (23 ° C.), it may be mixed with the base resin first after heating to lower the viscosity.

  Or, in the case of components that easily adhere to liquid organic compounds at room temperature, in addition to inorganic fillers that are difficult to adhere, coat the organic compounds with inorganic fillers, and then add the base resin and other components. Add and mix.

  In the present invention, the “other components” are organic compounds such as antioxidants and mold release agents, and are not organic compounds that are liquid at room temperature and have a low melting point (24 to 80 ° C.), that is, a melting point of 81. An organic compound having a temperature of ℃ or higher.

  Therefore, in the present invention, since the material is directly supplied to the injection molding apparatus and kneaded without kneading the material with an extruder and pelletizing, it is possible to suppress the deterioration of the resin performance. And since it has the process of mixing before supplying the material to the injection molding apparatus as described above, even if the material is directly supplied to the injection molding apparatus without kneading and pelletizing the material with a kneading extruder, It is possible to prevent the material from blocking the molding apparatus.

  In the present invention, the base resin is preferably in the range of 50 to 100 parts by weight, the organic compound in the range of 2 to 20 parts by weight, and the inorganic filler in the range of 20 to 40 parts by weight.

  In the present invention, since the organic compound that easily adheres to the injection molding apparatus is covered with an inorganic filler, the inorganic filler and the base resin preferably have more parts by weight than the organic compound, and the base resin is in the range of 50 to 100 parts by weight. On the other hand, when the organic compound is in the range of 2 to 20 parts by weight and the inorganic filler is in the range of 20 to 40 parts by weight, the performance of the base resin is not deteriorated, and the material is blocked in the injection molding apparatus. It is possible to provide an injection molding method capable of preventing the occurrence.

  In the present invention, in the step of mixing the materials, the materials are preferably stirred at 50 to 500 rpm for 5 to 30 minutes.

  In the present invention, since the organic compound needs to be covered with an inorganic filler, in the step of mixing the materials, it is preferable to mix while stirring, and the stirring condition is preferably 50 to 500 rpm and 5 to 30 min. If it is less than 50 rpm, the organic compound is hardly covered with the inorganic filler, and if it is more than 500 rpm, it takes time to start up and stop the stirrer, resulting in poor workability. Further, if it is less than 5 minutes, the mixing property is poor, and if it is more than 30 minutes, it takes too much time and work efficiency is poor.

  In the present invention, in the step of mixing the materials, when the organic compound is liquid at normal temperature (23 ° C.), the organic compound is solid at normal temperature at a temperature of 23 ° C. to 50 ° C. The material is preferably stirred at a temperature not lower than the melting point of the organic compound and not higher than the melting point of the organic compound + 30 ° C. or lower.

  In the present invention, the organic compound needs to be liquid when mixing the materials, but if the temperature is higher than necessary, the liquid viscosity is too low to mix. Therefore, when the organic compound is liquid at normal temperature (23 ° C.), it is at a temperature of 23 ° C. to 50 ° C., and when the organic compound is solid at normal temperature, the melting point of the organic compound is +30+ It is preferable that the temperature is not higher than ° C.

  In the present invention, it is preferable that the base resin is polylactic acid and the inorganic filler is phosphate.

  This shows a preferred specific example of the raw material to which the present invention is applied, and can be applied particularly preferably in the case of polylactic acid and phosphate.

  Moreover, in this invention, it is preferable to have a dull image structure in the screw metering part of the said injection molding apparatus.

  Since the screw metering portion of the injection molding device has a dull image structure, the base resin can be further sheared after being compressed and sheared, so that the effect of kneading and dispersing the material can be enhanced.

  According to the present invention, the material is directly melted by the injection molding apparatus without using the kneading extruder, so that the performance of the resin is not deteriorated and the material is blocked in the injection molding apparatus. It is possible to provide an injection molding method that can prevent the above-described problem.

Explanatory drawing explaining the injection molding method which concerns on this invention Explanatory drawing explaining the injection molding method which concerns on this invention Explanatory drawing explaining the structure of the injection molding apparatus used for the injection molding method of this invention Explanatory drawing explaining the screw structure of a screw compression part

  Hereinafter, an injection molding method according to the present invention will be described with reference to the drawings.

  1 and 2 are explanatory views for explaining an injection molding method according to the present invention.

  In order to reduce the thermal history of the base resin and suppress the deterioration of the resin performance, the present invention includes a step of kneading a material other than the conventional base resin into the base resin with a kneading extruder to form a pellet. It is something that is omitted.

  The material according to the present invention is at least a base resin, an organic compound having a melting point of 24 to 80 ° C. or an organic compound that is liquid at room temperature (23 ° C.) (hereinafter simply referred to as an organic compound), and an inorganic filler. Other materials include organic compounds such as antioxidants and mold release agents, which are not liquid and low melting point (24 to 80 ° C.) organic compounds at room temperature, that is, organic compounds having a melting point of 81 ° C. or higher. is there.

  If these materials are directly put into an injection molding apparatus without the step of pelletizing with a kneading extruder, the material will block the injection molding apparatus. That is, as a result of supplying all of the material directly to the injection molding device, if there is a component with a melting point of 80 ° C. or less, it melts with the heat from the heating cylinder of the injection molding machine and adheres to the inlet, and the material is supplied. Or the material is compressed due to the weight of the material at the inlet, blocking occurs, and the material cannot be supplied stably.

  Therefore, in the present invention, the process shown in FIG. 1 or FIG. 2 is performed in which the materials are mixed before being supplied to the injection molding apparatus.

  FIG. 1 shows that the organic compound 52 is first mixed with the base resin 50 and then the inorganic filler 54 and other components 58 are added and mixed as a step of mixing the material before supplying it to the injection molding apparatus. FIG.

  As shown in FIG. 1, first, the base resin 50 is charged into the stirring device 40. As the stirring device 40, for example, a tumbler mixer (SKD-50) manufactured by Seiwa Iron Works, or a tumbler mixer (TMHS-65) manufactured by Seiwa Giken is preferably used. Then, the organic compound 52 is put into the stirring device 40 containing the base resin 50 and stirred. Here, when the organic compound 52 is solid at normal temperature and has a melting point of 24 to 80 ° C., as shown in FIG. To mix. Further, when the organic compound is liquid at room temperature, it may be mixed as it is, but it is preferable to heat the organic compound 52 and then mix it with the base resin 50 as shown in (II) of FIG. .

  The stirring condition is preferably 50 to 500 rpm and 5 to 30 minutes. If it is less than 50 rpm, the organic compound is hardly covered with the inorganic filler, and if it is more than 500 rpm, it takes time to start up and stop the stirrer, resulting in poor workability. Further, if it is less than 5 minutes, the mixing property is poor, and if it is more than 30 minutes, it takes too much time and work efficiency is poor.

  When the base resin 50 and the organic compound 52 are mixed and the organic compound 52 uniformly adheres around the base resin 50, an inorganic filler 54 is added and mixed. If there are other components 58, the other components 58 are also charged and mixed.

  By feeding the mixed material into an injection molding apparatus 10 to be described later, even if the material is directly supplied to the injection molding apparatus without being kneaded and pelletized by a kneading extruder, the material is supplied to the injection molding apparatus. Can be prevented from blocking.

  FIG. 2 shows another embodiment of the present invention, in which the organic compound 52 is first mixed with the inorganic filler 54 and then mixed with the base resin 50 as a step of mixing the material before feeding it to the injection molding apparatus. It is the figure which showed adding the other component 58 and mixing.

  As shown in FIG. 2, first, the inorganic filler 54 is put into the stirring device 40. As the stirring device 40, for example, a tumbler mixer (SKD-50) manufactured by Seiwa Iron Works, and a tumbler mixer (TMHS-65) manufactured by Seiwa Giken are preferably used as in FIG. Then, the organic compound 52 that is liquid at room temperature is charged into the stirring device 40 containing the inorganic filler 54 and stirred.

  When the inorganic filler 54 and the organic compound 52 are mixed and the organic compound 52 is wrapped with the inorganic filler 54, the base resin 50 is added and mixed. In addition, when there is a component 58 of the conversion, other components 58 are also added and mixed.

  Even in such a mixed material, even if the material is directly supplied to the injection molding apparatus without being kneaded and pelletized by a kneading extruder by being put into an injection molding apparatus 10 to be described later, the injection molding apparatus It is possible to prevent the material from blocking.

  In the above-described step of mixing the materials, when the organic compound is liquid at normal temperature (23 ° C.), the organic compound is at a temperature of 23 ° C. to 50 ° C. and when the organic compound is solid at normal temperature. It is preferable to stir the material at a temperature not lower than the melting point of the organic compound and not higher than the melting point of the organic compound + 30 ° C. or lower.

  In the present invention, the organic compound needs to be liquid when mixing the materials, but if the temperature is higher than necessary, the liquid viscosity is too low to mix. Therefore, when the organic compound is liquid at normal temperature (23 ° C.), it is at a temperature of 23 ° C. to 50 ° C., and when the organic compound is solid at normal temperature, the melting point of the organic compound is +30+ It is preferable that the temperature is not higher than ° C.

  In the present invention, the base resin is preferably in the range of 50 to 100 parts by weight, the organic compound in the range of 2 to 20 parts by weight, and the inorganic filler in the range of 20 to 40 parts by weight.

  In the present invention, since the organic compound that easily adheres to the injection molding apparatus is covered with an inorganic filler, the inorganic filler and the base resin preferably have more parts by weight than the organic compound, and the base resin is in the range of 50 to 100 parts by weight. On the other hand, when the organic compound is in the range of 2 to 20 parts by weight and the inorganic filler is in the range of 20 to 40 parts by weight, the performance of the base resin is not deteriorated, and the material is blocked in the injection molding apparatus. Occurrence can be prevented. Moreover, when there are other components, the range of 0.5 to 10 parts by weight is preferable.

  Next, preferable conditions for the molding material used in the present invention will be described.

  The base resin used in the present invention can be applied to petroleum resins such as polylactic acid, acrylonitrile-butadiene-styrene (ABS), polycarbonate (PC), polystyrene (PS), etc. It is preferable to apply to biomass resin.

  Various types of polylactic acid resins can be used, and examples thereof include lactic acid homopolymer resins and lactic acid copolymer resins. Also, the lactic acid component that is a raw material of the polylactic acid resin is not particularly limited. For example, L-lactic acid, D-lactic acid, DL-lactic acid or a mixture thereof, or L-lactide or D-lactide that is a lactic acid cyclic dimer. , Meso-lactide, or mixtures thereof.

  The production method of the polylactic acid resin used in the present invention is not particularly limited, and various resins synthesized by a conventionally known method can be used. The lactic acid homopolymer resin is, for example, L-lactic acid, D-lactic acid, DL-lactic acid or the like, or a mixture thereof directly dehydrated or condensed, or L-lactide, D-lactide, meso-lactide, or these It can be obtained by ring-opening polymerization of a mixture or the like. The lactic acid copolymer resin can be obtained, for example, by copolymerizing a lactic acid monomer or lactide and another component copolymerizable with the monomer. Examples of other copolymerizable components include dicarboxylic acids, polyhydric alcohols, hydroxycarboxylic acids, lactones, etc. having two or more ester bond-forming functional groups in the molecule, and various constituents thereof. And various polyesters, various polyethers, and various polycarbonates.

  Further, the weight average molecular weight of the polylactic acid-based resin is not particularly limited, but is preferably 50,000 to 500,000, and more preferably 100,000 to 250,000.

  A weight average molecular weight of 50,000 or more is preferable because the strength of the obtained molded product of the present invention is further increased. A weight average molecular weight of 500,000 or less is preferable because the molding material used for injection molding tends to be uniform, and the strength of the resulting molded product tends to increase.

  The cellulose resin is not particularly limited, but diacetyl cellulose (DAC), triacetyl cellulose (TAC), cellulose acetate butyrate (CAB), and cellulose acetate propionate (CAP) can be preferably used. The particle size of the cellulosic resin supplied from the cellulosic resin manufacturer is generally supplied to the user as an irregular granule in the range of 1 to 30 mm.

  In the present invention, the content of the biomass resin that is the base resin of the molding material supplied to the injection molding machine is preferably 30% by mass or more, and more preferably 50% by mass or more. By setting it as such a structure, the outstanding environmental performance can be provided to the shape | molded fiber containing injection molded object.

  The organic compound (component that easily adheres) used in the present invention is a liquid at normal temperature (23 ° C.) or a solid having a low melting point (24 to 80 ° C.), and the purpose of addition is that of other additives (other components). It compatibilizes and disperses in the base resin, prevents hydrolysis of the base resin, becomes flame retardant, and plasticizes. Examples of liquids at room temperature (23 ° C.) include plastic esters such as adipic acids, benzoic acids, epoxidized fatty acid esters, phthalic acid esters, maleic acid esters, trimethyl phosphate, triethyl phosphate, sulfonamides, etc. Is mentioned. Solids having a low melting point (24 to 80 ° C.) at room temperature (23 ° C.) are, for example, stabuxol 1 LF, a hydrolysis inhibiting agent having a melting point of 40 ° C., stabuxol P having a melting point of 60 to 80 ° C. Examples include triphenyl acid (TPP).

  The inorganic compound (component that does not easily adhere) used in the present invention is a flame retardant such as phosphate or magnesium hydroxide, a pigment such as titanium oxide or carbon black, or an inorganic filler such as glass fiber, and is solid at room temperature. The shape of the inorganic compound may be any of granular, flat plate, and fiber. Other components include organic compounds that are liquid at normal temperature (23 ° C.) and not low melting point (24 to 80 ° C.), that is, organic compounds that are solid at 80 ° C. or less, and are antioxidants and release agents. Etc.

  There is no limitation in particular in a flame retardant (flame retardant), Various well-known flame retardants used in order to flame-retard resin (molded article) can be utilized. Examples include brominated flame retardants, chlorine-based flame retardants, phosphorus-containing flame retardants, silicon-containing flame retardants, nitrogen compound-based flame retardants, and inorganic flame retardants. Among these, phosphorus-containing flame retardants that have little flame retardant effect and have little possibility of adversely affecting the environment when incineration and disposal of molded products with less corrosion of equipment and molds during kneading and molding with resins Is preferred.

  There is no limitation in particular as a phosphorus containing flame retardant, A well-known thing can be used. For example, organic phosphorus compounds such as phosphoric acid esters, phosphoric acid condensed esters, and polyphosphates are exemplified. Specifically, as the phosphate ester, as an example, trimethyl phosphate, triethyl phosphate, tributyl phosphate, tri (2-ethylhexyl) phosphate, tributoxyethyl phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, Tris (isopropylphenyl) phosphate, tris (phenylphenyl) phosphate, trinaphthyl phosphate, cresyl diphenyl phosphate, xylenyl diphenyl phosphate, diphenyl (2-ethylhexyl) phosphate, di (isopropylphenyl) phenyl phosphate, monoisodecyl phosphate, 2-acryloyloxyethyl acid phosphate, 2-methacryloyloxyethyl acid phosphate , Diphenyl-2-acryloyloxyethyl phosphate, diphenyl-2-methacryloyloxyethyl phosphate, melamine phosphate, dimelamine phosphate, melamine pyrophosphate, triphenylphosphine oxide, tricresylphosphine oxide, diphenyl methanephosphonate, phenylphosphonic acid Examples include diethyl and the like.

  Examples of phosphoric acid condensed esters include resorcinol polyphenyl phosphate, resorcinol poly (di-2,6-xylyl) phosphate, bisphenol A polycresyl phosphate, hydroquinone poly (2,6-xylyl) phosphate, and these Aromatic phosphoric acid condensed esters such as condensates are exemplified.

  Furthermore, the polyphosphate which consists of a salt with phosphoric acid, polyphosphoric acid, the metal of group IA-IVB of periodic table, ammonia, an aliphatic amine, and an aromatic amine can also be mentioned.

  As typical salts of polyphosphates, lithium salts, sodium salts, calcium salts, barium salts, iron (II) salts, iron (III) salts, aluminum salts and the like as metal salts, methylamine salts as aliphatic amine salts, Examples include ethylamine salts, diethylamine salts, triethylamine salts, ethylenediamine salts, piperazine salts, and examples of aromatic amine salts include pyridine salts and triazines.

  Moreover, in this invention, you may use another flame retardant other than these phosphorus containing flame retardants and silicon containing flame retardants as needed. For example, magnesium hydroxide, aluminum hydroxide, antimony trioxide, antimony pentoxide, sodium antimonate, zinc hydroxystannate, zinc stannate, metastannic acid, tin oxide, tin oxide salt, zinc sulfate, zinc oxide, first oxide Iron, ferric oxide, stannous oxide, stannic oxide, zinc borate, ammonium borate, ammonium octamolybdate, metal salt of tungstic acid, complex oxide acid of tungsten and metalloid, ammonium sulfamate, Inorganic flame retardants such as ammonium bromide, zirconium compounds, guanidine compounds, fluorine compounds, graphite, and swellable graphite can be used.

  Other inorganic compounds include talc, kaolinite, montmorillonite, synthetic mica, clay, zeolite, silica, graphite, carbon black, zinc oxide, magnesium oxide, titanium oxide, calcium sulfide, boron nitride, calcium carbonate, barium sulfate, Examples include aluminum oxide, neodymium oxide, and metal salts of phenylphosphonate.

  FIG. 3 is a schematic diagram showing an example of an injection molding apparatus that can carry out the injection molding method of the present invention.

  As shown in FIG. 3, the basic in-line injection molding apparatus 10 includes a heating cylinder 14 having a nozzle 12 at the tip, and an injection screw 16 is disposed in the heating cylinder 14. A heater 18 is attached to the outer periphery of the heating cylinder 14, and a hopper 20 that supplies the material 22 to the injection screw 16 is attached to the opposite end of the nozzle 12. At the opposite end of the nozzle 12, the screw 16 is rotated at the rear end of the injection screw 16, and the screw 16 is advanced in the axial direction (left and right in FIG. 3) with the set values of the pressure and flow rate (speed) of the hydraulic oil. A hydraulic motor / cylinder set 26 for causing the injection operation and a load cell 24 for detecting the injection pressure are provided. The tip of the nozzle 12 is connected to a fixed mold 30 and a gate 34 of a movable mold 32 that form a cavity 28 therein.

  The material 22 charged from the hopper 20 is subjected to plasticizing operation including resin transfer, compression, kneading, melting, and metering operation by the rotating injection screw 16 and the heater 18. The injection screw 16 is moved in the direction of the nozzle 12 while the moving speed is controlled by the hydraulic motor / cylinder set 26, and the molten resin discharged from the nozzle 12 at a constant speed is filled into the cavity 28, and the setting is maintained for a predetermined time. The molded product is molded by being cooled while being kept under pressure.

  Here, the actual temperature under the hopper 20 of the injection molding apparatus 10 is 40 to 60 ° C. due to heat transfer from the cylinder 14, and rises as the cylinder 14 is approached. Therefore, if the material composed of at least the base resin, the organic compound, and the inorganic filler described above is normally supplied to the hopper, even if the organic compound is solid at room temperature (23 ° C.), the low melting point (24 The organic compound (˜80 ° C.) frequently adheres to the hopper wall to cause bridging and blocking, or frequently adheres to a groove between the flights of the screw and cannot convey the material.

  Therefore, in the present invention, a process of mixing the materials shown in FIGS. 1 and 2 before being supplied to the injection molding apparatus is performed.

  Therefore, in the present invention, when the material is directly supplied to the material inlet of the injection molding apparatus, when mixing the material components, it adheres to the hopper wall and bridges or blocks, or adheres to the groove between the flights of the screw. The organic compound, which is a component that easily adheres to the material that cannot be transported, is first mixed with the base resin, and then coated with an inorganic filler or other component that is difficult to adhere to. did. If the organic compound is solid at room temperature, the organic compound is heated and melted, then mixed with the base resin first, and then coated with an inorganic filler, which is a component that is difficult to adhere to. To do. Or, in the case of components that easily adhere to liquid organic compounds at room temperature, in addition to inorganic fillers that are difficult to adhere, coat the organic compounds with inorganic fillers, and then add the base resin and other components. Add and mix.

  As described above, the present invention can directly supply and knead the material to the injection molding apparatus without kneading the material with an extruder and pelletizing it, thereby suppressing deterioration of the resin performance. be able to. And since it has the process of mixing before supplying the material to the injection molding apparatus as described above, even if the material is directly supplied to the injection molding apparatus without kneading and pelletizing the material with a kneading extruder, It is possible to prevent the material from blocking the molding apparatus.

  In addition, in the injection molding apparatus 10 which concerns on this invention, it is preferable to have the dull image structure 16A in the measurement part of the screw 16, as shown in FIG. Since the screw metering portion of the injection molding device has a dull image structure, the base resin can be further sheared after being compressed and sheared, so that the effect of kneading and dispersing the material can be enhanced. The dull image structure is a width that fits within the full flight width of a normal screw (see FIG. 3), has a concave and convex tooth shape, and the convex teeth are inclined in the same direction as full flight. . The effect of kneading / dispersion is enhanced by increasing the number of dalmage structures to three, five, and seven rather than one.

  Although the injection molding method of the present invention has been described in detail above, the present invention is not limited to the above embodiment, and various improvements and modifications may be made without departing from the gist of the present invention. Of course.

  Next, it was tested what the material transportability and the material dispersibility would be in the example satisfying the injection molding method of the present invention and the comparative example not satisfied.

[material]
Polylactic acid was used as the base resin. Polylactic acid was tested by Unitika TE2000 and TE7000.

  A hydrolysis inhibitor was used as an organic compound (a component that easily adheres). As the hydrolysis inhibitor, the test was conducted with Stabuxol 1, LF and Stabuxol P manufactured by Rhein Chemie.

  Phosphate was used as an inorganic compound (a component that hardly adheres). The test was conducted using AP422 and AP423 manufactured by Clariant Japan, and FP2200 manufactured by Adeka as phosphates.

  Antioxidants were used as other components. A test was conducted with Irganox 245 manufactured by Ciba Specialty Chemicals as an antioxidant.

  The base resin is in the range of 50 to 100 parts by weight, the organic compound (adhesive component) is in the range of 2 to 20 parts by weight, the inorganic filler is in the range of 20 to 40 parts by weight, and the other components are in the range of 0.5 to The range of 10 parts by weight was tested with the formulation described below. In addition, although the bulk specific gravity of the base resin, the organic compound, the inorganic filler, and the inorganic filler was measured, all were in the range of 0.7 to 1.0 g / ml.

・ Base resin: Polylactic acid (pellet)
Unita TE2000 100 parts by weight-Organic compound (component that easily adheres): Hydrolysis inhibitor (granular)
Rhein Chemie Stavaxol 1 LF 2 parts by weight-Inorganic compounds (components that are difficult to adhere): Flame retardant (granular)
AP422 40 parts by weight manufactured by Clariant Japan Co., Ltd. ・ Other ingredients: Antioxidant (granular)
0.5 parts by weight of Irganox 245 manufactured by Ciba Specialty Chemicals [Mixing method]
Examples 1-4 and the comparative example were performed on the mixing conditions shown below.

Example 1
An organic compound (a component that easily adheres) was first mixed with the base resin, and then an inorganic compound (a component that does not easily adhere) and other components were added and coated.

(Example 2)
Components with a low melting point (24-80 ° C) of organic compounds (components that tend to adhere) are heated and melted, then mixed with the base resin first, and then mixed with inorganic compounds (components that are difficult to adhere) and other The ingredients were added and coated.

(Example 3)
An organic compound (a component that easily adheres) was added to an inorganic compound (a component that is difficult to adhere) and coated, and then a base resin and other components were added and mixed.

Example 4
The organic compound (component that tends to adhere) was heated to lower the viscosity, and then mixed with the base resin first, and then the inorganic compound (component that does not adhere easily) and other components were added and coated.

(Comparative example)
An organic compound (a component that easily adheres), an inorganic compound (a component that hardly adheres), a base resin, and other components were mixed simultaneously.

[Test evaluation]
(Evaluation of material transportability)
Evaluation was performed from the viewpoint of whether the material was not clogged with a hopper or whether the material could be sent out with a screw. The evaluation criteria are as follows.

  A: The material can be fed out with a screw without being clogged with the hopper when the material is sufficiently put into the hopper (10 shots or more).

  ○: With 5 shots of material supply, the material can be sent out with a screw without clogging with a hopper.

  Δ: The material can be fed by a screw without being clogged by a hopper with a material supply for one shot.

  X: It is clogged with a hopper and a material cannot be sent out with a screw.

(Evaluation of material dispersibility)
The material melted by the injection molding apparatus was evaluated using the following test pieces. An injection-molded test piece having a length of 127 mm, a width of 12.7 mm, and a thickness of 1.6 mm according to the UL94 standard was used. A test piece is placed on a light table (white light) having an illuminance of 3800 to 4200 Lx, and visually observed with transmitted light. The evaluation criteria are as follows.
(Double-circle): It is uniform (good) without the lump and nonuniformity of an addition component.
○ There is no lump of added components, but there is slight unevenness.
Δ: Observed visually with transmitted light, there are few lumps of added components.
X: The mass of the added component is clearly observed by visual observation with transmitted light.

  [Evaluation results]

  From the above experiment, it can be seen that the material transportability and the material dispersibility (mixability) are good by directly melting the material by the injection molding method of the present invention in the injection molding apparatus.

  Therefore, according to the present invention, by directly melting the material with an injection molding apparatus without using a kneading extruder, the performance of the resin is not deteriorated, and the material is blocked in the injection molding apparatus. An injection molding method that can prevent this can be provided.

  DESCRIPTION OF SYMBOLS 10 ... Injection molding apparatus, 12 ... Nozzle, 14 ... Cylinder, 16 ... Screw, 16A ... Dalmage structure, 18 ... Heater, 20 ... Hopper, 22 ... Material, 24 ... Load cell, 26 ... Hydraulic motor and cylinder set, 28 ... Cavity , 30 ... fixed mold, 32 ... movable mold, 34 ... gate, 40 ... stirrer, 50 ... base resin, 52 ... organic compound (solid at a melting point of 24 to 80 ° C or liquid at room temperature), 54 ... inorganic Filler, 58 ... other ingredients

Claims (10)

At least a base resin, an organic compound that is liquid at normal temperature, and an inorganic filler, and an injection molding method in which the material is supplied to an injection molding apparatus and kneaded and melted.
Mixing the material before feeding it to an injection molding device;
In this step, the organic compound is first mixed with the base resin, and then the inorganic filler and other components are added and mixed.   The injection molding method according to claim 1, wherein the organic compound is heated and then mixed with the base resin. This is an injection molding method in which at least a base resin, an organic compound that is solid at room temperature and has a melting point of 24 to 80 ° C., and an inorganic filler are used as materials, supplied to an injection molding device, kneaded and melted. And
Mixing the material before feeding it to an injection molding device;
In this step, the organic compound is heated and melted, the melted organic compound is first mixed with the base resin, and then the inorganic filler and other components are added and mixed. Injection molding method. At least a base resin, an organic compound that is liquid at normal temperature, and an inorganic filler, and an injection molding method in which the material is supplied to an injection molding apparatus and kneaded and melted.
Mixing the material before feeding it to an injection molding device;
In this step, the organic compound is first mixed with the inorganic filler, and then the base resin and other components are added and mixed.   The base resin is in the range of 50 to 100 parts by weight, the organic compound is in the range of 2 to 20 parts by weight, and the inorganic filler is in the range of 20 to 40 parts by weight. 5. The injection molding method according to any one of 4.   6. The injection molding method according to claim 1, wherein in the step of mixing the materials, the materials are stirred at 50 to 500 rpm for 5 to 30 minutes.   In the step of mixing the materials, when the organic compound is liquid at normal temperature, the temperature is 23 ° C. or higher and 50 ° C. or lower. When the organic compound is solid at normal temperature, the organic compound is higher than the melting point of the organic compound. The injection molding method according to any one of claims 1 to 6, wherein the material is stirred at a temperature of the melting point of the organic compound + 30 ° C or lower. The injection molding method according to any one of claims 1 to 7, wherein the base resin is polylactic acid. The injection molding method according to any one of claims 1 to 8, wherein the inorganic filler is a phosphate. The injection molding method according to claim 1, wherein the screw metering portion of the injection molding apparatus has a dull image structure.

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