JP2012187767A - Mixing method, injection molding method, and mixing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mixing method that can uniformly mix materials, and to provide an injection molding method and a mixing apparatus.SOLUTION: In the mixing method, at least two different materials are mixed by a tumbler 40 (container-revolving type mixing apparatus). A fixing plate 42 having a delomorphous hole or a fixing plate 42' comprising a mesh is provided in the tumbler 40 for mixture.

Description

  The present invention relates to a mixing method, an injection molding method, and a mixing apparatus, and more particularly to a mixing method, an injection molding method, and a mixing apparatus in which at least two kinds of materials are mixed by a tumbler.

  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 biomass resin is used as a molding material and a molded product is manufactured by injection molding, there are some major problems described below.

(Flame retardancy)
When a member is made by molding a biomass resin, particularly PLA, flame retardancy is often required. In materials such as home appliances, PCs, and automobiles, a high degree of flame retardancy is required from the viewpoint of fire and fire spread suppression. There is a UL standard in the United States as a standard for flame retardancy, but recently, high-level flame retardants such as V-1 and V-0 have been required for biomass molded members. In order to cope with this, it is necessary to incorporate a large amount of flame retardant into the resin. For example, it is necessary to knead 40 parts by weight or more of the flame retardant with respect to 100 parts by weight of PLA. Then, although the PLA resin is originally a brittle material that does not easily generate strength, the strength of the PLA molded body is lowered to a level that cannot be practically used by adding powder (a flame retardant).

  In order to increase the strength, it is only necessary to reduce the brittleness of the material. For this purpose, it is necessary to add a flexible rubber component, elastomer or the like.

  However, these flexible components are flammable and intended to impart flame retardancy, but due to an attempt to increase strength, sufficient flame retardancy may not be obtained, resulting in a balance between flame retardancy and strength. . This balance is very difficult.

  Concomitant with this problem, flame retardants need to be added in small amounts, especially those that are highly effective, so as not to reduce strength, and must use high-performance and expensive flame retardants. There is also a problem that up is inevitable.

  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, which 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 fibers, and the fiber portion may be replaced with a carbon neutral material. However, these methods are also difficult to obtain physical properties at a practical level, and the necessity of adding a large amount of flame retardant has not been solved.

(Low heat resistance)
PLA has a problem in processing that heat resistance is lower than that of general-purpose resin.

  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. The setting range is narrowly 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 if possible, the biomass resin and the flame retardant can be pelletized in advance and then supplied to the injection molding apparatus. preferable. 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.

  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.

  As described above, as a prior art of injection molding, it is widely known that a material pelletized by a compound method or a master batch method is introduced into a material supply port of an injection molding apparatus. 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. It was used only to do.

  Therefore, in order to solve the above problems and suppress the degradation of the biomass resin, simplify the process and reduce the cost, it is conceivable to replace it with a “direct molding method” in which the material is directly fed into the material inlet of the injection molding apparatus. . This is because it is considered that the problems described here can be solved if each material can be fed into the molding apparatus as a mixed material without being pelletized. However, just mixing the ingredients and supplying them does not work, and there is a problem that needs to be solved in order to form a member by the “direct molding method”.

  The injection molding apparatus is basically based on heat-melting (also called plasticization) a pellet-shaped thermoplastic resin and injecting it into a mold. Although a small amount of powder can be added, if a large amount of powder is supplied at the same time as the pellet, the function of sufficiently stirring and dispersing them in the screw of the injection molding machine is low, and it is difficult to obtain a uniform molded product.

  As mentioned above, when it is difficult to balance flame retardancy and strength in PLA resin moldings, and high flame retardancy is required, for example, trying to pass UL V-0 grade In the UL combustion test, it is important that the test piece does not melt and flow down when the test piece burns.

  For this reason, it is necessary to add an “anti-drip agent” that prevents the test piece from melting and flowing down. For this purpose, it is effective to add fine particles that do not melt.

  That is, various additives are required as components of the PLA resin molded body, and in order to provide a member that can be used as a product, a flame retardant (not limited to one type. Required), an anti-drip agent that assists the function of the flame retardant, a softener (rubber component), and the like are required. In fact, in addition to these, it is necessary to add many components such as a compatibilizing agent for facilitating the compatibility of the additive such as a softener with PLA, an anti-degradation agent that suppresses the decomposition of PLA, an antioxidant, and a pigment. .

  Thus, when trying to obtain a molded article having a desired performance by blending additives in a well-balanced manner, it is necessary to select materials that are particularly effective for the flame retardant and the anti-drip agent.

  In particular, as the flame retardant, a polyphosphoric acid flame retardant having a high phosphorus concentration and a high flame retardant effect is effective. However, this flame retardant is a powder, and there is a problem that the powder is easily consolidated to form aggregated particles. If it is taken out from the bag, it contains a lot of large aggregates of several centimeters.

  In addition, as the anti-drip agent, it has been found that fine talc is particularly effective, but it is a fine powder of 10 μm or less. There are difficulties in handling such as transportation.

  Since there was a concern about the hygiene problem of the operator's suction of fine powder, handling properties and dispersibility during mixing were improved by using aggregated particles of about 20 μm.

  Further, even if these materials are directly supplied to the injection molding machine as they are, a uniform molded body cannot be obtained. Therefore, it is necessary to sufficiently mix and stir in advance.

  However, with a normal stirring device, the aggregates of the flame retardant were not fully charged and decomposed, and a homogeneous injection-molded product could not be obtained. If the flame retardant is made sufficiently fine, then the talc that formed the corner aggregates will be crushed and returned to a fine powder and separated in the material, so that a homogeneous injection-molded body can still be produced. There wasn't.

  In other words, in the direct supply molding that directly supplies the mixed material to the injection molding machine, the material can be mixed sufficiently, and the aggregate of the flame retardant in question can be sufficiently loosened. It is preferable that the agglomerates can be left with the crushing suppressed, and as a result, the material in the molded body is sufficiently dispersed to satisfy the physical properties.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a mixing method, an injection molding method, and a mixing apparatus that can uniformly mix materials.

  In order to achieve the above object, the present invention is a mixing method in which at least two kinds of different materials are mixed by a container rotary mixer, and a fixed hole having a fixed hole is provided inside the container of the container rotary mixer. Provided is a mixing method comprising mixing by providing a plate or a fixed plate made of a mesh.

  According to the present invention, two different types of materials can be mixed uniformly.

  In the present invention, the dimensions of the holes of the fixing plate are preferably such that the shortest length is 10 mm or more and 15 mm or less, and the longest length is 10 mm or more and 20 mm or less.

  In the present invention, the opening ratio of the fixing plate is preferably 25% or more and 70% or less of the fixing plate and 3% or more and 15% or less of the total surface area in the container.

  In the present invention, it is preferable that the fixing plate has a semi-elliptical shape and is inclined by 30 ° or more and 50 ° or less with respect to the symmetry axis of the container.

  In this invention, it is preferable to mix as the material filling rate in the said container is 40% or more and 70% or less.

  In the present invention, the at least two different materials are preferably a flame retardant and at least one of a resin pellet and a nucleating agent. In the present invention, the resin pellet is preferably a resin pellet made of polylactic acid. In the present invention, the nucleating agent is preferably talc.

  In the present invention, at least two kinds of materials are mixed by a container rotary mixer, and a fixed plate having a fixed hole or a fixed plate made of mesh is mixed inside the container of the container rotary mixer. Thus, the materials can be mixed uniformly.

  In particular, in the case where at least two kinds of materials are a flame retardant and at least one of a resin pellet and a nucleating agent, the resin pellet is about several mm in diameter, and the nucleating agent is originally a fine particle having a diameter of several μm. Although it is a powder, the flame retardant is originally a powder, but it is compressed and thickened during transportation, and the powder is consolidated to produce a large number of aggregated particles of about 5 mm to 30 mm.

  Even if the agglomerated flame retardant is mixed, the agglomerated particles are not easily broken and do not easily become uniform. Therefore, even if the mixed material is put into the injection molding machine as it is, the aggregated particles are intermittently supplied, and the quality of the molded body is not stable.

  Moreover, since the nucleating agent is originally a fine powder having a diameter of several μm, it is easy to separate and difficult to handle. Therefore, it is necessary to improve the mixing property by using particles having a large particle size (apparent specific gravity is large) as aggregated particles of 10 to 20 μm until they are supplied to the injection molding machine. However, if mixed too strongly, the aggregates are destroyed and returned to fine particles and separated.

  That is, it is required to break and mix large agglomerated particles of 5 to 30 mm and to mix fine powders having a diameter of several μm without breaking.

  Therefore, the present inventor has found that it is preferable to mix a material by providing a fixed plate having a fixed hole or a fixed plate made of mesh inside the container of the container rotary mixing device.

  In the present invention, a fixed plate for improving the mixing property of materials is mounted in a rotary mixing container (hereinafter also referred to as a tumbler). The fixed hole of the fixed plate is a grater for aggregated particles. The agglomerated particles are scraped little by little due to the effect (or cheese cutter), but other particles have an effect that they are easily slipped out of the regular holes and are not easily broken. Therefore, at least two kinds of materials are mixed by a tumbler, and the material can be uniformly mixed by providing and mixing a fixed plate having a fixed hole or a fixed plate made of mesh inside the tumbler.

  In addition, it is preferable to mix the material filling rate in the tumbler as 40% or more and 70% or less. If the material filling rate is higher than 70%, the material is crushed due to the restriction of the movement of the material. This is because when the material filling rate is less than 40%, the space is too large, the impact of the material on the fixed plate is increased, and the generation of fine powder increases.

  In the present invention, in the tumbler, the at least two kinds of materials are preferably mixed at 30 to 100 rpm for 10 to 30 minutes.

  If it is less than 30 rpm, the mixing property is poor, and large aggregates cannot be crushed, leaving “dama”. If it is greater than 100 rpm, the impact of the material on the fixed plate will increase and the generation of fine powder will increase. Moreover, when it is less than 10 minutes, it will not fully mix, and when it is more than 30 minutes, it will become difficult to disperse | distribute instead of returning the aggregate which has been aggregated to the fine powder. In addition, it takes too much time for the mixing process, and the work efficiency is lowered.

  In the present invention, in order to achieve the above object, it is preferable that the mixed material mixed by the mixing method described above is supplied to an injection molding apparatus and injection molded.

  In order to achieve the above object, the present invention provides a mixing apparatus characterized in that a fixed plate having a fixed hole or a fixed plate made of a mesh is provided inside a container of a container rotating type mixing apparatus.

  In the present invention, in order to achieve the above object, the opening ratio of the fixing plate is 25% or more and 70% or less of the fixing plate and 3% or more and 15% or less of the total surface area in the container. Is preferred.

  In the present invention, in order to achieve the above object, it is preferable that the fixing plate has a semi-elliptical shape and is inclined by 30 ° or more and 45 ° or less with respect to the symmetry axis of the container.

  ADVANTAGE OF THE INVENTION According to this invention, the mixing method, the injection molding method, and mixing apparatus which can mix a material uniformly can be provided.

Explanatory drawing explaining the injection molding method which concerns on this invention The explanatory view which looked at the mixing device concerning the present invention from the upper surface Explanatory drawing explaining the structure of the mixing apparatus which concerns on this invention Explanatory drawing which shows the effect of this invention Explanatory drawing which shows the example of the fixed hole which concerns on this invention Explanatory drawing explaining the structure of the injection molding apparatus used for the injection molding method of this invention Example table

  Hereinafter, a mixing method and an injection molding method according to the present invention will be described with reference to the drawings. FIG. 1 is an explanatory view for explaining an injection molding method according to the present invention.

  In the present invention, in order to reduce the heat history of the resin and suppress the deterioration of the resin performance, the step of kneading the material other than the conventional resin into the resin with a kneading extruder to be pelletized is omitted. It is a thing.

  In the mixing method and the injection molding method according to the present invention, at least two kinds of materials are mixed.

  FIG. 1 is a diagram showing that resin pellets 50, a nucleating agent 52, and a flame retardant 54 are added and mixed as a step of mixing materials before being supplied to an injection molding apparatus. In the present invention, the material is not limited to the resin pellet 50, the nucleating agent 52, and the flame retardant 54.

  As shown in FIG. 1, first, the weighed material is put into a rotary mixing device (tumbler) 40. The mixing device 40 is not particularly limited as long as it is a container rotation type stirring device, and any type of stirring device can be used as long as the performance required in this patent can be exhibited.

  Specifically, Seiwa Ironworks tumbler mixer, Seiwa Giken tumbler mixer and drum shaker, Platec tumbler mixer, Toyo Hitech drum hoop mixer, Aichi Electric Co., Ltd. An example is a rocking mixer.

  More specifically, for example, a tumbler mixer (SKD-50) manufactured by Seiwa Iron Works, a tumbler mixer (TMHS-65) manufactured by Seiwa Giken is preferably used.

  And the mixed material mixed with the mixing apparatus 40 is sent to the supply apparatus 60 in FIG.

  The supply device 60 cuts and supplies a desired amount of the mixed material to the injection molding device 10.

  Here, just mixing the materials with a tumbler and supplying them to the injection molding apparatus 10 will not work. The materials that must be mixed have various properties, such as talc aggregates with a diameter of 10 to 20 μm, flame retardants that are compressed to form hard aggregates with a diameter of 5 to 30 mm, and resin pellets with a diameter of 2 to 4 mm. In addition, each material has a wide specific gravity range from 0.14 (apparent specific gravity of fine powder talc) to 1.1 (apparent specific gravity of PLA resin), so these materials should be mixed uniformly. Is difficult.

  In particular, the case of the flame retardant 54 and at least one of the resin pellet 50 and the nucleating agent 52 will be described. The resin pellet is a fine powder having a diameter of about 2 to 4 mm and the nucleating agent is originally a few μm in diameter. However, the aggregate is made into particles of 10 to 20 μm. Although the flame retardant is originally a powder, it is compressed and thickened during transportation, and the powder is consolidated to produce many aggregated particles of about 5 mm to 30 mm.

  The agglomerated flame retardant 54 is not easily broken even when mixed, and does not easily become uniform. Therefore, even if the mixed material is put into the injection molding apparatus as it is, the aggregated particles are intermittently supplied, and the quality of the molded body is not stable.

  Moreover, since the nucleating agent 52 is originally a fine powder having a diameter of several μm, it is easy to separate and difficult to handle. Therefore, until it is supplied to the injection molding apparatus, it is devised to improve the mixing property by using particles having a large particle size (apparent specific gravity is large) as 10-20 μm agglomerated particles. However, if mixed too strongly, the aggregates are destroyed and returned to fine particles and separated.

  That is, it is required that large agglomerated particles of 5 to 30 mm are broken and mixed, and small agglomerates having a diameter of 10 to 20 μm are mixed without breaking.

  Therefore, as shown in FIG. 2, the present inventor should provide a fixed plate 42 having a fixed hole or a fixed plate 42 ′ made of mesh inside the tumbler 40 to mix the materials. I found it.

  As shown in FIGS. 2 and 3A, in the present invention, a fixing plate 42 (42 ') for increasing the mixing of materials is attached inside the tumbler 40. As shown in FIG. 4 (A), the fixed holes or mesh of the fixing plate scrape the agglomerated particles little by little due to an effect like a grater (or a cheese cutter) for large agglomerated particles. To go.

  And as shown to FIG. 4 (B), about other microparticles, it slips easily from a fixed hole or a mesh. That is, other particles, particularly talc that is deliberately supplied as agglomerated particles (from the viewpoint of handling) has an effect that the fixed plate 42 (42 ') is difficult to break.

  Therefore, two or more different materials can be uniformly mixed by providing and mixing a fixed plate having a fixed hole or a fixed plate made of mesh inside the tumbler.

  Note that, as shown in FIG. 2A, the shape of the hole does not need to be round, but may be oval, square, or rhombus. And although it is preferable that the hole is uniformly opened with respect to the whole fixed plate 42 surface, it does not need to be uniform. In addition, the holes may be formed directly in the fixed plate, or a material such as expanded metal may be used as the fixed plate.

  As the mesh, a mesh like a regular wire knitted can be used, but welded kanaami, in which the crossing points of the wires are welded, is preferable in terms of strength and opening stability.

  Examples of these holes and meshes are shown in FIGS. Note that the dimensions described in FIGS. 5A to 5D are examples, and are not limited to these dimensions.

  If the hole shape is extremely long, there is a concern that the eyes may open when the weight of the material is applied to the fixed plate during the rotation of the container, which is not preferable. In this case, there is a method of increasing the strength by increasing the thickness of the fixed plate, but the weight of the rotating container increases and a large rotational power is required.

  In addition, since the direction of material flow changes depending on the direction in which the container is inclined, if the hole is too long, the effect may be greatly reduced depending on the direction of material flow, which is not preferable. Since the same thing is concerned when the shape of a hole is indefinite, it is not preferable.

  Therefore, the hole shape is preferably a round hole, a point-symmetric shape, or a shape close to it, which does not have a very large aspect ratio and hardly causes a difference in the pulverization, distribution, and mixing functions regardless of the direction of material flow. In the present invention, the minimum length of the hole is preferably 10 mm to 15 mm, and the maximum length is preferably 10 mm to 20 mm.

  In the present invention, the opening ratio of the fixing plate 42 (42 ') is preferably 25% or more and 70% or less of the fixing plate and 3% or more and 15% or less of the total surface area in the container.

  And in this invention, as shown to FIG. 3 (B), in this invention, it is preferable that the fixed plate is a semi-elliptical shape, and is provided inclining 30 degrees or more and 50 degrees or less with respect to the symmetric axis of a tumbler ( (See FIG. 3A).

  Moreover, in this invention, it is preferable to mix the material filling rate in the said tumbler as 40% or more and 70% or less. In addition, it is preferable to mix the material filling rate in the tumbler as 40% or more and 70% or less. If the material filling rate is higher than 70%, the material is crushed due to the restriction of the movement of the material. This is because when the material filling rate is less than 40%, the space is too large, the impact of the material on the fixed plate is increased, and the generation of fine powder increases.

  The mixing conditions are preferably 30 to 100 rpm and 10 to 30 minutes. When it is less than 30 rpm, mixing is not sufficiently performed, and large aggregated particles cannot be sufficiently pulverized. If it is higher than 100 rpm, the flow of the material in the container does not proceed smoothly, resulting in poor mixing. Similarly, if the mixing time is less than 10 minutes, the mixing property is poor, and if it is more than 30 minutes, the particles that are flocculated are broken and the fine particles are separated, and the mixing process takes too much time and the working efficiency is deteriorated. Is produced.

  Next, preferable conditions such as materials used in the present invention will be described.

  The resin pellet resin used in the present invention is applicable to petroleum resins such as polylactic acid, acrylonitrile-butadiene-styrene (ABS), polycarbonate (PC), polystyrene (PS), etc. It is preferable to apply to resin biomass resin. That is, it is necessary to add many additives to the biomass resin in order to achieve both strength and flame retardancy, and molding is often performed with a prescription containing aggregates that are desired to be fine and aggregates that are not desired to be crushed.

  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 other components copolymerizable with the monomer. Other components that can be copolymerized include, for example, dicarboxylic acids, polyhydric alcohols, hydroxycarboxylic acids, lactones, etc. having two or more ester bond-forming functional groups in the molecule, and various components 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, which is a 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.

  Examples of the material used in the present invention include materials that are compatibilized and dispersed in the resin, hydrolysis of the base resin, flame resistance, and plasticization. Examples of the plasticizer include adipic acids, benzoic acids, epoxidized fatty acid esters, phthalate esters, maleate esters, phosphate esters such as trimethyl phosphate and triethyl phosphate, and sulfonamides.

  Examples of the material used in the present invention include flame retardants such as phosphate and magnesium hydroxide, pigments such as titanium oxide and carbon black, and inorganic fillers such as glass fibers. The shape of the inorganic filler may be any of granular, flat plate, and fiber. Examples of other components include an antioxidant and a release agent.

  There are no particular limitations on the flame retardant, and various known flame retardants that are used for flame retarding a resin (molded product) can be used. 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, a phosphorus-containing flame retardant having a large flame retardant effect is preferable, and a polyphosphoric acid flame retardant is particularly preferable from the viewpoint of reducing the addition amount as much as possible and not reducing the strength of the resin molded body.

  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, a periodic table group IA-IVB group metal, 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, etc. 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 together another flame retardant other than these 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.

  In this patent, it was found that fine particle talc is effective as an anti-drip agent during combustion, and also functions as a nucleating agent that promotes crystallization of PLA. It is preferable to use fine particle talc which is relatively inexpensive and has a combined action without using an agent. Of course, other nucleating agents can be used in combination.

  FIG. 6 is a schematic configuration 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. 6, 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. 4) with the set values of the pressure and flow rate (speed) of the hydraulic oil. A hydraulic motor / cylinder set 26 for causing an injection operation and a load cell 24 for detecting 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 operations including material transfer, compression, melting, kneading, and metering operations by the injection screw 16 and the heater 18. The injection screw 16 is moved toward the nozzle 12 while the moving speed is controlled by the hydraulic motor / cylinder set or the electric feed screw mechanism 26, and the molten resin discharged from the nozzle 12 at a constant speed is filled into the cavity 28, The molded product is molded by cooling while being held at the set holding pressure for a predetermined time.

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

[Example]
Next, it was tested how the dispersibility of the material would be in an example satisfying the injection molding method (mixing method) of the present invention and a comparative example not satisfied.

[material]
・ Polylactic acid resin pellets: Unitika TE4000 100 parts by weight ・ Ammonium polyphosphate based retarder: Clariant AP422 45 parts by weight ・ Compatibilizer: Fushimi Pharmaceutical Ravitor FP110 16 parts by weight ・ Plasticizer: Riken Vitamins Riquemar S74 3 parts by weight Hydrolysis inhibitor: Rhein Chemie Stavaxol 1FL 4 parts by weight Nucleating agent: Nihon Talc custom-made product (aggregated particles 20 μm) 5 parts by weight Antioxidant: Ciba Specialty Chemicals Irganox 245
0.5 part by weight Anti-drip agent: Daikin Industries, Ltd. FA500H 0.5 part by weight [mixing method]
The materials were mixed using a cylindrical tumbler having a height of 450 mm and a diameter of Φ430 mm.

  Examples and Comparative Examples were performed under the mixing conditions shown in the table of FIG. In addition, the shape of the hole of the fixing plate was mixed in any shape shown in FIG.

[Test evaluation]
((Evaluation of visual dispersibility))
Evaluation was made by using the following test pieces as materials obtained by melting the materials mixed in the above-described Examples and Comparative Examples with an injection molding apparatus. 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 of dispersibility by elongation))
A material obtained by melting the materials mixed in the above-described examples and comparative examples with an injection molding apparatus was injection-molded into the following test pieces for evaluation. A JIS (K-7113 compliant No. 1 test piece) dumbbell was prepared by injection molding. With Shimadzu Autograph AGS-J, it is pulled until it breaks at a grip interval of 100 mm and a pulling speed (50) mm / sec, and the elongation at break is expressed as a percentage of the original sample length (100 mm) as the elongation value of that sample. did.

((Flame resistance evaluation))
As the test piece, an injection molded test piece having a length of 127 mm, a width of 12.7 mm, and a thickness of 1.6 mm was used. UL94-V is a basic flammability test for plastic parts and the like, and a flame of a gas burner is applied to a test piece of a prescribed size to examine the degree of combustion of the test piece. The grades are 5VA, 5VB, V-0, V-1, V-2, and HB in descending order of flame retardancy. The flame retardance of V-1 or higher is regarded as acceptable (O), and V- A flame retardance of 2 or less was regarded as rejected (x).

[Evaluation results]
From the above experiment, it can be seen that the dispersibility (mixability) of the material is good by providing and mixing a fixed plate having a fixed hole or a fixed plate made of mesh inside the tumbler.

  It can also be seen that the dispersibility (mixability) of the material is better when the aperture ratio of the fixed plate is 25% to 70% of the fixed plate and is 3% or more and 15% or less of the total surface area of the tumbler.

  Furthermore, it can be seen that when the material filling rate in the tumbler is 40% to 70%, the dispersibility (mixability) of the material is better.

  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 ... mixing device (tumbler), 50 ... resin pellet, 52 ... nucleating agent, 54 ... flame retardant

Claims (13)

A mixing method in which at least two different materials are mixed by a container rotary mixing device,
A mixing method comprising mixing by providing a fixed plate having a fixed hole or a fixed plate made of a mesh inside a container of the container rotary mixing device.   2. The mixing method according to claim 1, wherein the holes of the fixing plate have a minimum length of 10 mm to 15 mm and a maximum length of 10 mm to 20 mm.   The opening ratio of the fixing plate is 25% or more and 70% or less of the fixing plate, and is 3% or more and 15% or less of the total surface area in the container. Mixing method.   The mixing plate according to any one of claims 1 to 3, wherein the fixing plate has a semi-elliptical shape and is inclined by 30 ° or more and 50 ° or less with respect to an axis of symmetry of the container. Method.   The mixing method according to any one of claims 1 to 4, wherein mixing is performed at a material filling rate of 40% to 70% in the container.   The mixing method according to claim 1, wherein the at least two different materials are any one of a flame retardant and at least a resin pellet and a nucleating agent.   The mixing method according to claim 6, wherein the resin pellet is a resin pellet made of polylactic acid.   The mixing method according to claim 6 or 7, wherein the nucleating agent is talc.   The mixing method according to any one of claims 1 to 8, wherein in the container rotating mixing device, the at least two kinds of materials are mixed at 30 to 100 rpm for 10 to 30 minutes.   An injection molding method, wherein the mixed material mixed by the mixing method according to any one of claims 1 to 8 is supplied to an injection molding apparatus to perform injection molding.   A mixing apparatus, wherein a fixed plate having a fixed hole or a fixed plate made of a mesh is provided inside a container of a container rotary mixing device.   The mixing device according to claim 11, wherein an opening ratio of the fixing plate is 25% or more and 70% or less of the fixing plate and 3% or more and 15% or less of a total surface area in the container. .   The mixing device according to claim 11 or 12, wherein the fixing plate has a semi-elliptical shape and is inclined by 30 ° or more and 45 ° or less with respect to an axis of symmetry of the container.

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