Flame retardant granulates, method for producing the same, and use thereof

Abstract

To provide a flame retardant granule capable of improving handleability, safety, and a work environment improvability for a non-bromine-based powder flame retardant and contributing to improvement of productivity of a resin composition or a resin molding blended with a high concentration of the flame retardance.SOLUTION: This flame retardant granule is formed by binding a non-bromine-based powder flame retardant. According to one embodiment, the flame retardant granule includes the non-bromine-based powder flame retardant of 40°C or higher and lower than 150°C. According to one embodiment, the flame retardant granule includes the non-bromine-based powder flame retardant which can be bound through action of a liquid.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a flame retardant granule, a method for producing the flame retardant granule, and use thereof.

Background Art

[0002] In order to impart flame retardancy to a thermoplastic resin or an elastomer, a powdery flame retardant may be blended. In recent years, from the viewpoint of environmental protection, the use of phosphorus-containing compound-based flame retardants, nitrogen-containing compound-based flame retardants, inorganic flame retardants, or metal salt-based flame retardants as non-bromine flame retardants has been increasing. However, in flame retardancy standards typified by the UL94 standard, a high level of flame retardancy is increasingly required. For this reason, the amount of the flame retardant blended in the resin composition tends to increase.

[0003] Powdery flame retardants generally have a low bulk specific gravity, poor fluidity during transfer, and strong adhesion to processing machines and transport pipes. As a result, problems in handling such as transport, storage, packaging, and supply stability to processing machines often occur. In addition, there are many problems to be solved in terms of the working environment and safety for the human body. In particular, when a powdery flame retardant is blended with a thermoplastic resin or an elastomer using a melt-kneading apparatus (for example, an extruder), especially when a high-concentration flame retardant is blended, the supply of the powdery flame retardant to the melt-kneading apparatus becomes an obstacle, resulting in large variations in the composition, and further, due to a feed neck (poor supply), the production rate (discharge rate) of melt-kneading significantly decreases.

[0004] Patent Document 1 proposes granulating a powdery flame retardant. By granulating the powdery flame retardant, the handleability can be greatly improved. However, in Patent Document 1, for non-bromine-based flame retardants, the binding force of the flame retardant is insufficient, and it is easily disintegrated, which may cause problems regarding handleability. In addition, when a hydrocarbon-based compound is used as a binder to increase the binding force of the granulated product, there is a problem that the flame retardancy decreases.

Prior Art Documents

Patent Documents

[0005] Patent Document 1 Japanese Patent Application Laid-Open No. 8-92562 Summary of the Invention Problems to be Solved by the Invention

[0006] The present invention has been made to solve the above problems, and an object thereof is to improve the handleability, safety, and work environment improvement of a non-brominated powdery flame retardant, and to contribute to the improvement of the productivity of a resin composition or a resin molded product in which a high concentration of a flame retardant is blended. It is to provide a flame retardant granule. Means for Solving the Problems

[0007] The flame retardant granule of the present invention is composed of a non-brominated powdery flame retardant bound thereto. In one embodiment, the flame retardant granule contains a non-brominated powdery flame retardant having a melting point of 40°C or higher and less than 150°C. In one embodiment, the flame retardant granule contains a non-brominated powdery flame retardant that can be bound by the action of a liquid. In one embodiment, the flame retardant granule further contains a binder. In one embodiment, the content ratio of the non-brominated powdery flame retardant is 80 parts by weight to 99.9 parts by weight with respect to 100 parts by weight of the total amount of the non-brominated powdery flame retardant and the binder. In one embodiment, the non-brominated powdery flame retardant is at least one selected from the group consisting of a phosphorus-containing compound-based flame retardant, a nitrogen-containing compound-based flame retardant, an inorganic-based flame retardant, and a metal salt-based flame retardant. In one embodiment, the non-brominated powdery flame retardant having a melting point of 40°C or higher and less than 150°C is at least one selected from the group consisting of an aromatic phosphate ester compound, an aromatic condensed phosphate ester compound, and a cyclic phosphazene compound. According to another aspect of the present invention, there is provided a method for producing the flame retardant granulate. This production method includes a mixing step of mixing the non-bromine-based powdery flame retardant and water, a granulation step of granulating the mixture obtained through the mixing step to obtain a granulate precursor, and a drying step of drying the granulate precursor. In one embodiment, the production method includes a mixing step of mixing the non-bromine-based powdery flame retardant, water, and a binder, a granulation step of granulating the mixture obtained through the mixing step to obtain a granulate precursor, and a drying step of drying the granulate precursor. In one embodiment, the granulation step includes granulating by a semi-wet granulation method. In one embodiment, the granulation step includes performing granulation by a disk pelletizer method. According to still another aspect of the present invention, there is provided the use of the flame retardant granulate as a raw material for a molding material or a thermoplastic resin compound.

Advantages of the Invention

[0008] According to the present invention, for a non-bromine-based powdery flame retardant, it is possible to improve handleability, safety, and work environment improvement, and it is possible to provide a flame retardant granulate that can contribute to the improvement of productivity of a resin composition or a resin molded product in which the flame retardant is compounded at a high concentration.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Modes for Carrying Out the Invention

[0010] A. Overview of the flame retardant granulate The flame retardant granulate of the present invention is composed of a non-bromine-based powdery flame retardant bound together. The non-bromine-based powdery flame retardant can be bound by any suitable action.

[0011] In one embodiment, the flame retardant granulate contains a non-brominated powdery flame retardant having a melting point of 40°C or higher and lower than 150°C as the non-brominated powdery flame retardant. In one embodiment, the flame retardant granulate contains a binder. In one embodiment, the non-brominated powdery flame retardant having a melting point of 40°C or higher and lower than 150°C and the binder can be used in combination. In one embodiment, the flame retardant granulate is composed of the non-brominated powdery flame retardant bound by the non-brominated powdery flame retardant having a melting point of 40°C or higher and lower than 150°C and / or the binder.

[0012] In one embodiment, due to the granulation method, the binding property of the flame retardant granulate is exhibited. For example, the flame retardant granulate contains, as the non-brominated powdery flame retardant, a non-brominated powdery flame retardant that can be bound by the action of a liquid. The flame retardant granulate containing such a non-brominated powdery flame retardant can be obtained, for example, in a wet granulation method (stirring granulation method) by forming a liquid crosslink through the interaction between the non-brominated powdery flame retardant and a liquid (for example, water). In one embodiment, the non-brominated powdery flame retardant that can be bound by the action of a liquid can be used in combination with a binder and / or a non-brominated powdery flame retardant having a melting point of 40°C or higher and lower than 150°C.

[0013] In addition, in this specification, the flame retardant means a substance that can impart flame retardancy to a molded body containing a predetermined amount of the flame retardant and prevent the fire from spreading even if the molded body catches fire. Also, in this specification, the "binder" is a concept that does not include the flame retardant.

[0014] Further, the non-brominated powdery flame retardant means a powdery flame retardant composed of a compound that does not contain a bromine atom. In this specification, hereinafter, the non-brominated powdery flame retardant is also simply referred to as a powdery flame retardant. Also, the "non-brominated powdery flame retardant having a melting point of 40°C or higher and lower than 150°C" is also referred to as a binding powdery flame retardant.

[0015] The above flame retardant granulate can exhibit appropriate binding force (i.e., granulate hardness) and excellent flame retardancy. The above flame retardant granulate can be added to and used in the resin composition in various plasticized melting processes of thermoplastic resins, including the melt compounding (melt kneading) of the resin composition. By using the above flame retardant granulate, the productivity of the flame retardant-containing resin composition can be improved. Specifically, since the above flame retardant granulate is significantly excellent in the charging stability to devices such as extruders, the productivity (compounding processing speed per hour) of the flame retardant-containing resin composition can be remarkably improved by using the flame retardant granulate. In addition, it can significantly improve the pollution of the working environment by dust, improve the labor safety and health environment of workers, and can greatly shorten the time for equipment switching and cleaning. Further, by using the flame retardant granulate of the present invention, it is also possible to manufacture resin compositions or resin molded products in which a powdery flame retardant is compounded at a high concentration with high productivity. Furthermore, by using a powdery flame retardant (binding powdery flame retardant) having a melting point of 40°C or higher and less than 150°C, or a non-bromine-based powdery flame retardant that can be bound by the action of a liquid, a flame retardant granulate can be obtained that is produced with better efficiency and is excellent in quality stability (shape stability, hardness uniformity) and high hardness.

[0016] In one embodiment, the flame retardant granulate does not contain a binder. Such a flame retardant granulate can be obtained when the powdery flame retardant has self-binding properties. For example, it can be obtained by using a binding powdery flame retardant or a non-bromine-based powdery flame retardant that can be bound by the action of a liquid. The flame retardant granulate configured without using a binder is advantageous in that it can exhibit high flame retardancy.

[0017] In one embodiment, the above flame retardant granulate is manufactured by a semi-wet granulation method. According to the semi-wet granulation method, the above effects become remarkable. Details will be described later.

[0018] The above flame retardant granulate can have any appropriate shape. Typically, the above flame retardant granulate is cylindrical (pellet-shaped).

[0019] When the above-mentioned flame retardant granulate is cylindrical, the diameter of the above-mentioned flame retardant granulate is, for example, 2 mm to 5 mm. Further, the length (height) of the flame retardant granulate is, for example, 1 mm to 7 mm. With such a shape, a flame retardant granulate that is easy to handle can be obtained. The diameter of the flame retardant granulate can be adjusted, for example, by the diameter of the die hole of the disk plate during granulation, and the length can be adjusted by the distance between the disk plate and the cutter. By matching the shape and size of the flame retardant granulate with the pellet size of the resin used in combination, the handleability is improved, and the dispersibility of the flame retardant in the melt compound is improved.

[0020] The breaking stress of the above-mentioned flame retardant granulate in a wooden hardness meter is preferably 0.05 kg to 10 kg, more preferably 0.5 kg to 7 kg, and still more preferably 1.0 kg to 5 kg. Within such a range, a flame retardant granulate excellent in handleability and melt processability can be obtained. Here, the breaking stress indicates the average collapse stress measured for 20 or more (preferably 25 or more) particles.

[0021] The moisture content of the above-mentioned flame retardant granulate can be any appropriate moisture content. The moisture content of the above-mentioned flame retardant granulate is preferably 10% by weight or less, more preferably 5% by weight or less, still more preferably 3% by weight or less, particularly preferably 1% by weight or less, and most preferably 0.5% by weight or less. The moisture content of the flame retardant granulate is measured using an infrared moisture meter as described later.

[0022] The bulk density of the above-mentioned flame retardant granulate is preferably 0.3 kg / L to 2.0 kg / L, more preferably 0.5 kg / L to 1.0 kg / L. By increasing the bulk density, the supply rate and supply stability of the flame retardant granulate are increased when performing melt kneading. The bulk density is calculated by using a liter, allowing the powder to fall naturally into the liter until it is full, accurately measuring the volume of 1 liter, and measuring its weight (unit: kg / L).

[0023] A-1. Non-bromine-based powdery flame retardant As long as the effects of the present invention can be obtained, the content ratio of the non-bromine-based powdery flame retardant (powdery flame retardant) can be set to any appropriate ratio. When the above flame retardant granulate contains a binder, the content ratio of the powdery flame retardant is preferably 50 parts by weight to 99.9 parts by weight, more preferably 60 parts by weight to 99.9 parts by weight, still more preferably 80 parts by weight to 99.9 parts by weight, particularly preferably 90 parts by weight to 99.9 parts by weight, and most preferably 95 parts by weight to 99.9 parts by weight, based on 100 parts by weight of the total amount of the powdery flame retardant and the binder. Within such a range, the effects of the present invention become remarkable.

[0024] The particle size of the above powdery flame retardant can be set to any appropriate size. The number average particle size of the powdery flame retardant is, for example, 10 nm to 1 mm, preferably 1 μm to 500 μm, more preferably 5 μm to 300 μm, and still more preferably 10 μm to 200 μm. Within such a range, the productivity of the flame retardant granulate can be enhanced. The particle size of the powdery flame retardant can be determined by the laser diffraction method.

[0025] The bulk density of the above powdery flame retardant is preferably 0.01 kg / L to 1 kg / L, more preferably 0.05 kg / L to 0.8 kg / L, and still more preferably 0.1 kg / L to 0.5 kg / L. When the bulk density of the powdery flame retardant is within the above range, the production rate per unit time of the flame retardant granulate can be increased. In the above flame retardant granulate, by forming the granulate, it is advantageous in that the supply stability and supply accuracy can be improved while containing a powdery flame retardant with a low bulk density. By using the flame retardant granulate, it becomes possible to stably obtain a flame retardant-containing resin composition with high productivity.

[0026] In one embodiment, as the above powdery flame retardant, a flame retardant used for rubber, resin, etc. is used.

[0027] In one embodiment, the powdery flame retardant is at least one selected from the group consisting of a phosphorus-containing compound-based flame retardant, a nitrogen-containing compound-based flame retardant, an inorganic flame retardant, and a metal salt-based flame retardant. By using these flame retardants, the effects can be preferably exerted as a flame retardant granule. The powdery flame retardant may be used alone or in combination of two or more kinds.

[0028] Examples of the phosphorus-containing compound-based flame retardant include phosphate esters and condensed phosphate esters, and triphenyl phosphate and 1,3-phenylenebis(dixylenyl) phosphate can be exemplified.

[0029] Examples of the nitrogen-containing compound-based flame retardant include, for example, dialkylphosphinic acid and / or its salts, condensation products of melamine, reaction products of melamine and phosphoric acid, reaction products of condensation products of melamine and polyphosphoric acid, ammonium polyphosphate salts, benzoguanamine, tris(hydroxyethyl) isocyanurate, allantoin, glycoluril, melamine, melamine cyanurate, dicyandiamide, guanidine, etc. Other examples include phosphazenes, and specific examples include phenyl esters of phosphonitrilic acid. The nitrogen-containing compound-based flame retardant may contain phosphorus.

[0030] Specific examples of the inorganic flame retardant include magnesium oxide, calcium oxide, aluminum oxide, zinc oxide, manganese oxide, tin oxide, antimony oxide, boehmite, dihydrotalcite, hydrocalumite, magnesium hydroxide, calcium hydroxide, aluminum hydroxide, zinc hydroxide, tin oxide hydrate, manganese hydroxide, zinc borate, basic zinc silicate, zinc stannate, red phosphorus, etc.

[0031] Examples of the metal salt-based flame retardant include, for example, metal salts of organic phosphinic acids, metal salts of organic sulfones, and metal salts of perfluoroalkane sulfonic acids, and specific examples include aluminum tris(diethylphosphinate) and potassium perfluorobutane sulfonate.

[0032] As described above, the flame retardant granulate can include, as a non-bromine-based powdery flame retardant, a non-bromine-based powdery flame retardant (adhesive powdery flame retardant) having a melting point of 40°C or higher and lower than 150°C. As the adhesive powdery flame retardant, phosphate esters, condensed phosphate esters, nitrogen-containing compound-based flame retardants, etc. can be used. In one embodiment, at least one selected from the group consisting of aromatic phosphate ester compounds, aromatic condensed phosphate ester compounds, and cyclic phosphazene compounds is used as the adhesive powdery flame retardant. Examples of the adhesive powdery flame retardant include triphenyl phosphate (melting point: 50°C), 1,3-phenylene bis(dixylenyl) phosphate (melting point: 92°C), phosphazene compounds, etc. As the phosphazene compound, a cyclic phenoxyphosphazene compound is more preferable, and in particular, a cyclic phenoxyphosphazene compound containing 70% by mass or more, preferably 85% by mass or more of the trimer is desirable, and phenyl phosphonitrilate (melting point: 110°C) can be exemplified.

[0033] The content ratio of the adhesive powdery flame retardant is preferably 0.1 part by weight to 100 parts by weight per 100 parts by weight of the powdery flame retardant. In one embodiment, the content ratio of the adhesive powdery flame retardant is preferably 0.1 part by weight to 20 parts by weight, more preferably 0.5 part by weight to 15 parts by weight, and still more preferably 1 part by weight to 10 parts by weight per 100 parts by weight of the powdery flame retardant. In another embodiment, the content ratio of the adhesive powdery flame retardant is preferably 70 parts by weight to 100 parts by weight, more preferably 80 parts by weight to 100 parts by weight, and still more preferably 90 parts by weight to 100 parts by weight per 100 parts by weight of the powdery flame retardant. In yet another embodiment, all of the powdery flame retardant is the adhesive powdery flame retardant.

[0034] As described above, the flame retardant granulate can contain, as a non-brominated powdery flame retardant, a non-brominated powdery flame retardant that can be bound by the action of a liquid. Examples of the powdery flame retardant include aluminum tris(diethylphosphinate). Although the detailed action is not clear, when aluminum tris(diethylphosphinate) is used as the powdery flame retardant, it is considered that in the semi-wet granulation process, water intervenes between the powdery flame retardants, and a liquid crosslink is formed by the interaction between the powdery flame retardant and water, thereby obtaining the flame retardant granulate. Since aluminum tris(diethylphosphinate) does not melt and has excellent heat resistance, when using this compound, a flame retardant granulate that can be preferably used for engineering plastics with a high melt processing temperature can be obtained.

[0035] The content ratio of the non-brominated powdery flame retardant that can be bound by the action of a liquid is preferably 0.1 part by weight to 100 parts by weight in 100 parts by weight of the powdery flame retardant. In one embodiment, the content ratio of the non-brominated powdery flame retardant that can be bound by the action of a liquid is preferably 70 parts by weight to 100 parts by weight in 100 parts by weight of the powdery flame retardant, more preferably 80 parts by weight to 100 parts by weight, and still more preferably 90 parts by weight to 100 parts by weight. In another embodiment, all of the powdery flame retardant is a powdery flame retardant that can be bound by the action of a liquid. In still another embodiment, all of the powdery flame retardant is a bindable powdery flame retardant and a non-brominated powdery flame retardant that can be bound by the action of a liquid.

[0036] In the powdery flame retardant, the melting point of the powdery flame retardant that does not correspond to the bindable powdery flame retardant is preferably 150°C or higher, more preferably 200°C or higher, and still more preferably 300°C or higher. Also, a powdery flame retardant that thermally decomposes without melting may be used. A powdery flame retardant with a high melting point or that does not melt is preferable in that the shape can be preferably maintained even when heated during the production of the flame retardant granulate. By using a powdery flame retardant with a high melting point and / or a powdery flame retardant that does not melt in combination with the bindable powdery flame retardant, a flame retardant granulate with high shape retention and excellent flame retardancy can be obtained.

[0037] A-2. Binder In this specification, "binder" means a substance that binds a non-brominated powdery flame retardant. The softening temperature of the above binder is preferably 40°C or higher and less than 150°C. Within such a range, a flame retardant granule with excellent binding strength can be obtained. More specifically, a binder having a softening temperature within the above range melts or softens during the granulation process or heating process of the flame retardant granule, conforms to the surface of the powdery flame retardant, and then cools and solidifies again, thereby being able to exert the function and effect as a binder well. The softening temperature of the above binder is preferably 50°C or higher and less than 145°C, more preferably 60°C or higher and less than 140°C, and still more preferably 70°C or higher and less than 135°C. Within such a range, the effects of the present invention become remarkable. The softening temperature means the melting point or glass transition temperature and can be measured by a differential scanning calorimeter (DSC). In one embodiment, in the above DSC measurement, when an endothermic or exothermic peak is observed, the softening temperature corresponds to the melting point, and when a discontinuity in the baseline is observed, the softening temperature corresponds to the glass transition temperature.

[0038] The above binder is preferably a powder at normal temperature. If the binder is a powder, it is preferable in the dispersion and mixing with the powdery flame retardant.

[0039] The number average particle diameter of the binder can be any appropriate size. For example, it is 1 μm to 1 mm, preferably 5 μm to 500 μm, more preferably 10 μm to 300 μm, and still more preferably 20 μm to 200 μm. The particle diameter of the binder can be determined by the laser diffraction method.

[0040] The content ratio of the above binder can be set to any appropriate ratio according to the size, shape, water absorbency, oil absorbency, bulk density, etc. of the powdery flame retardant to be granulated. When using a binder, the content ratio of the above binder is preferably 0.1 part by weight to 20 parts by weight, preferably 0.5 part by weight to 15 parts by weight, and more preferably 1 part by weight to 10 parts by weight with respect to a total of 100 parts by weight of the powdery flame retardant and the binder. If it is within such a range, the binding force to the powdery flame retardant is preferably exhibited, and a flame retardant granulated product excellent in handleability can be obtained.

[0041] In one embodiment, the above binder can be composed of any appropriate resin. Examples of the resin constituting the binder include polyolefin resins, polyvinyl alcohol resins, polyalkylene glycol resins, polyvinyl pyrrolidone resins, polyester resins, polyamide resins, acrylic resins, polyurethane resins, epoxy resins, etc. In another embodiment, polysaccharides are used as the above binder. The binder may be used alone or in combination of two or more. In one embodiment, the resin constituting the binder can be preferably selected from polyolefin resins, polyester resins, and polyamide resins. Using these resins is advantageous in terms of obtaining a flame retardant granulated product excellent in binding force to the powder raw material and excellent in shape stability. Among these, in particular, those having a hot melt adhesiveness function can be preferably used.

[0042] The above flame retardant granulated product may contain any appropriate other additives as required. Examples of the additive powder include antioxidants, light stabilizers, foaming agents, ultraviolet absorbers, anti-blocking agents, heat stabilizers, impact modifiers, antibacterial agents, dispersants, compatibilizers, processing aids, lubricants, coupling agents, crystallization nucleating agents, hydrolysis inhibitors, deoxidizers, colorants (dyes and pigments), etc.

[0043] Also, if necessary, a flame retardant aid may be added. Examples of the flame retardant aid include aluminum phosphite, iron oxide, borax, zinc borate, barium metaborate, zirconium oxide, molybdenum oxide, and in addition, antimony compounds such as antimony trioxide, antimony tetroxide, antimony pentoxide, sodium antimonate, and antimony phosphate. The flame retardant aid can be used singly or in combination of two or more kinds.

[0044] B. Manufacturing method of the flame retardant granulate The above-mentioned flame retardant granule can be produced by any suitable method. For example, the flame retardant granule can be obtained by subjecting a mixture containing the above-mentioned powdery flame retardant, water, and, if necessary, a binder added thereto to a semi-wet granulation method.

[0045] In one embodiment, the method for producing the flame retardant granule includes a mixing step of mixing the powdery flame retardant and water, a granulation step of granulating the mixture obtained through the mixing step to obtain a granule precursor, and a drying step of drying the granule precursor. In the mixing step, the binder may be further mixed if necessary. Preferably, water is added to a powder mixture containing the binder and the powdery flame retardant.

[0046] In the mixing step, it is preferable to uniformly mix using any suitable mixer. Examples of the mixer include a Henschel mixer, a kneader for powder (KDH, KDA, CKD, CPM) (Dalton Co.), a Spartan mixer (SPM) (Dalton Co.), an SP granulator (SPG) (Dalton Co.), and the like.

[0047] The blending amount of water can be any appropriate amount depending on the characteristics (such as water absorption) of the powdery flame retardant. The blending amount of water is, for example, 5 parts by weight to 100 parts by weight, preferably 8 parts by weight to 70 parts by weight, more preferably 10 parts by weight to 50 parts by weight, and still more preferably 15 parts by weight to 30 parts by weight with respect to 100 parts by weight of the total amount of the powdery flame retardant and the binder. Within such a range, a mixture excellent in granulation properties can be obtained in the granulation process by the semi-wet method. By using such a mixture, a precursor of a flame retardant granule in which the powdery flame retardant is preferably bound can be stably obtained.

[0048] The water to be added is not particularly limited, and for example, tap water, distilled water, ion-exchanged water, hard water, soft water, etc. can be used. Also, it may be an alcohol aqueous solution obtained by adding alcohol or the like to water. The alcohol concentration of the alcohol aqueous solution is preferably 20% by weight or more, more preferably 40% by weight or more, and still more preferably 50% by weight or more.

[0049] It is preferable to add water to the powder mixture while uniformly dispersing it over a period of usually 1 to 60 minutes, preferably 3 to 30 minutes, and more preferably 5 to 20 minutes.

[0050] The mixing time in the mixing process can be any appropriate mixing time according to the types of components, the type of mixer, the component mixing ratio, etc. Preferably, the mixing time is set so that the materials are sufficiently and uniformly dispersed and mixed. In a high-speed stirrer such as a Henschel mixer or a Spartan mixer, the treatment time can be 1 to 10 minutes. On the other hand, in the case of a kneader for powders, a treatment time of several minutes to 60 minutes may be required.

[0051] In the granulation process, the compression granulation method is preferably adopted. Also, in the granulation process, the semi-wet granulation method can be preferably adopted. Examples of the compression granulation method / semi-wet granulation method include a disk pelletizer method, a tableting method, a briquetting method, etc. From the viewpoint of the balance between productivity and the quality of the obtained flame retardant granules, the disk pelletizer method is preferably adopted.

[0052] As a basic structure, a disk pelletizer has one or two disks with a large number of holes ranging from 2 mm to 30 mm, and a roller for pumping raw materials into the holes of the disks. The raw materials (powder mixtures containing moisture) supplied between the disk and the roller or between two disks are pressed into the holes of the disk as the roller rotates, and cylindrical extrudates are formed. The extruded granule precursor is cut by a cutter or the like on the back surface of the disk to obtain pellet-shaped flame retardant granules. The length of the granule precursor can be adjusted by the distance between the back surface of the disk and the cutter and the rotation speed of the roller. The distance between the disk plate and the cutter can be set to any appropriate distance according to the type of powder raw material and the like. The distance between the disk plate and the cutter is, for example, 1 mm to 30 mm, more preferably 2 mm to 20 mm, and even more preferably 3 mm to 10 mm.

[0053] More specifically, examples of the disk pelletizer method include the roller-disk die method, the roller-ring die method, the double die method, the flat die method, and the like. Examples of commercially available granulators using the disk pelletizer method include the disk pelletizer F series manufactured by Dalton.

[0054] As the drying method in the drying process, any appropriate method can be adopted. After the drying process, by performing treatment with a vibrating sieve or the like, a flame retardant granulated product from which fine powder has been removed can be obtained. In the drying process, any appropriate drying equipment is used. For example, a vibrating fluidized bed dryer is preferable because it can perform drying efficiently in a short time. For example, the vibrating fluidized bed dryer VDF series manufactured by Dalton can be cited. The drying temperature is usually preferably in the range of room temperature to 150°C and can be appropriately selected. In one embodiment, when using a binder powder flame retardant, the drying temperature is set to be equal to or higher than the melting point of the binder powder flame retardant (for example, a temperature 10°C to 50°C higher than the melting point of the binder powder flame retardant). In one embodiment, when using a binder, the drying temperature is set to be equal to or higher than the softening temperature of the binder (for example, a temperature 10°C to 50°C higher than the softening temperature of the binder). The drying time is appropriately selected according to the moisture content of the target flame retardant granulated product.

[0055] C. Melt compound using the flame retardant granulate In one embodiment, the above-mentioned flame retardant granulated product is used as a molding material or a raw material for a thermoplastic resin compound for its use. As the thermoplastic resin, any thermoplastic resin can be used.

[0056] As the method for producing the melt compound, any appropriate method can be adopted. For example, a kneader, a Banbury mixer, rolls, a single-screw or multi-screw extruder with two or more shafts can be used. Preferably, a twin-screw extruder is used. The composition obtained by melt-kneading is pelletized.

[0057] Specific examples of the above-mentioned thermoplastic resins include, for example, general-purpose resins such as high-density polyethylene (HDPE), medium-density polyethylene (MDPE), low-density polyethylene (LDPE), polypropylene (PP), polyvinyl chloride (PVC), polyvinylidene chloride, polystyrene (PS), polyvinyl acetate (PVAc), polyurethane (PUR), fluorine-based resins, ABS resin (acrylonitrile-butadiene-styrene resin), AS resin, acrylic resin (PMMA), etc., polyamides (PA), polyacetals (POM), polycarbonates (PC), polyphenylene ethers, modified polyphenylene ethers (m-PPE, modified PPE, PPO), polyesters (PET, PBT, etc.), engineering plastics such as cyclic polyolefins (COP), polyphenylene sulfide (PPS), polytetrafluoroethylene (PTFE), polysulfone (PSF), polyethersulfone (PES), amorphous polyarylate (PAR), liquid crystal polymer (LCP), polyetherimide (PEI), polyetheretherketone (PEEK), super engineering plastics such as thermoplastic polyimide (TPI), polyamideimide (PAI), etc.

[0058] In addition, a biodegradable polymer may be used as the above-mentioned thermoplastic resin. Examples of the biodegradable polymer include, for example, aliphatic polyester-based resins (for example, homopolymers or copolymers such as polycaprolactone, polylactic acid, polyethylene succinate, polybutylene succinate adipate, polyhydroxyvalerate, etc., modified products of these homopolymers or copolymers), aliphatic-aromatic polyester resins (for example, block polymers or random polymers such as aliphatic carboxylic acids or hydroxy acids, aromatic dicarboxylic acids and 1,3-propanediol), polyvinyl alcohol-based resins (for example, polyvinyl alcohol, polyvinyl acetate, polyvinyl butyrate, ethylene-vinyl alcohol copolymer, etc.).

[0059] In the melt compound of the above thermoplastic resin and the above flame retardant granulate, since the above flame retardant granulate is excellent in the charging ability and stability to a melt kneading apparatus such as an extruder, the productivity of the resin composition can be remarkably improved, and the flame retardant dispersibility in the resin is also excellent. Further, it greatly contributes to the improvement of the working environment and the labor safety and health environment of the workers.

Examples

[0060] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples in any way. Note that parts and % are based on weight unless otherwise specified.

[0061] Reference Example 2 100 parts by weight of a powdery flame retardant (aluminum tris(diethylphosphinate), manufactured by Clariant, trade name "Exolit OP1230"; average particle diameter: 30 μm, bulk density: 0.59 kg / L; in the table, "A-1") was charged into an FM mixer (manufactured by Nippon Coke & Engineering Co., Ltd., trade name "5FM5C / I"; processing volume: 5 L). The blades of the FM mixer were a combination of upper blades and lower blades. The upper blades were Y1 blades (trade name, manufactured by Nippon Coke Co., Ltd.), and the lower blades were S0 blades (trade name, manufactured by Nippon Coke Co., Ltd.). In addition, a baffle plate (also referred to as a buffer or a deflector) was installed in the stirring tank. While rotating the stirring blades at a rotational speed of 1,000 rpm with respect to the above powdery flame retardant, 15 parts by weight of water was continuously spray-injected in a spray form over 5 minutes to obtain a water-containing mixture. This water-containing mixture was charged into a disk pelletizer (manufactured by Dalton, trade name "Disk Pelletizer F-5 / 11-175") to obtain a pellet-like granulate precursor. At this time, the pore diameter of the die was 3 mmφ, the thickness of the die plate was 15 mm, the effective length of the die hole was 12 mm, and the rotational speed of the roller of the pelletizer was 108 rpm. The obtained granulate precursor was dried at 140 °C for 4 hours using a hot air circulation dryer to obtain a flame retardant granulate (FRG-1). An external appearance photograph of the obtained flame retardant granulate (FRG-1) is shown in Fig. 1.​​

[0062] [Example 2] Into an FM mixer, 100 parts by weight of a powdery flame retardant (Exolit OP1230; “A-1” in the table) and 3 parts by weight of 1,3-phenylenebis(dixylenyl)phosphate (trade name: PX-200, manufactured by Daihachi Chemical Industry Co., Ltd., melting point: 92°C; “B-1” in the table) as a binding powdery flame retardant were charged, and stirred and mixed at a rotational speed of 1,000 revolutions for 2 minutes to obtain a powder mixture. The configuration of the blades of the FM mixer was Reference Example 2 the same as While rotating the stirring blades of the above powder mixture at a rotational speed of 1,000 rpm, 15 parts by weight of water was continuously spray-injected in a spray form over 5 minutes to obtain a water-containing powder mixture. This water-containing powder mixture was Reference Example 2 granulated in the same manner by a disk pelleter and dried at 120°C for 4 hours using a hot air circulation dryer to obtain a flame retardant granulated product (FRG-2). An external appearance photograph of the obtained flame retardant granulated product (FRG-2) is shown in Fig. 2.

[0063] [Example 3] A flame retardant granulated product (FRG-3) was obtained by the same operation as in Example 2 except that the binding powdery flame retardant was changed to 3 parts by weight of phosphazene (phenyl phosphonitrilic acid ester) (trade name: Labitol FP-110, manufactured by Fushimi Pharmaceutical Co., Ltd., melting point: 110°C; “B-2” in the table).

[0064] [Example 4] Into an FM mixer, 100 parts by weight of a powdery flame retardant (untreated magnesium hydroxide powder) (trade name: Junmag BF, manufactured by Fimatech Co., Ltd., average particle diameter 12 μm; “A-2” in the table) and 10 parts by weight of 1,3-phenylenebis(dixylenyl)phosphate (PX-200; “B-1” in the table)) as a binding powdery flame retardant were charged, and stirred and mixed at a rotational speed of 1,000 revolutions for 2 minutes to obtain a powder mixture. The configuration of the blades of the FM mixer was Reference Example 2 the same as While rotating the stirring blades at 1,000 rpm, 10 parts by weight of water was continuously spray-injected into the above powder mixture in a spray form over 5 minutes to obtain a water-containing powder mixture. This water-containing powder mixture was Reference Example 2 granulated by a disk pelleter in the same manner as [Example 4], and dried at 120°C for 4 hours using a hot air circulation dryer to obtain a flame retardant granulate (FRG-4).

[0065] [Example 5] The powdery flame retardant was changed to 1,3-phenylenebis(dixylenyl)phosphate (PX-200; “B-1” in the table), and except that the drying conditions of the granulate precursor were changed to 80°C for 4 hours Reference Example 2 a flame retardant granulate (FRG-5) was obtained in the same manner as [Example 4].

[0066] [Reference Example 1] Reference Example 1 is Reference Example 2 the same composition as [Example 4], but the blades of the FM mixer were such that the upper blades were ST blades (product name, manufactured by Nippon Coke Co., Ltd.) and the lower blades were A0 blades (product name, manufactured by Nippon Coke Co., Ltd.), the baffle plate was removed, 15 parts by weight of water was put into the FM mixer at once, and stirring treatment was carried out at 1,000 rpm for 5 minutes to obtain a powder mixture. The granulation and drying treatments were Reference Example 2 the same as [Example 4] (FRG-C1).

[0067] [Comparative Example 1] An attempt was made to produce a flame retardant granulate (FRG-C2) in the same manner as in Example 4, except that the cohesive powdery flame retardant was not added.

[0068] The specific details of each component used in the examples, comparative examples, and reference examples are as shown in Table 1.

Table 1

[0069] <Evaluation> Reference Example 2, Examples 2~5, the flame retardant granulates obtained in Reference Example 1 and Comparative Example 1 were subjected to the following evaluations. The results are shown in Table 2. (1) Granulation property The granulation property of the flame retardant granulate was evaluated according to the following criteria. 〇: Granulates with a diameter of 3 mmφ can be obtained. △: It forms granulates, but there is a large variation in the binding force. ×: It forms granulates, but the binding force is insufficient and it is prone to disintegration. (2) Granulation speed The production speed (kg / Hr) of the flame retardant granulate per hour was calculated. (3) Bulk density The flame retardant granulate after drying was allowed to fall naturally into a 1-liter graduated cylinder, filled to the brim, and accurately weighed with a volume of 1 liter to calculate the bulk density (unit: kg / L) of the flame retardant granulate. (4) Pellet size Twenty flame retardant granulates were taken out, and the average values of the length and diameter of the granular materials were calculated using vernier calipers. (5) Moisture content The moisture content (unit: weight%) remaining in the flame retardant granulate was measured using an infrared moisture meter (FD-660 manufactured by Kett Scientific Laboratory Co., Ltd.). (6) Disintegration strength measurement Using a wooden hardness tester (manufactured by Shiro Sangyo Co., Ltd., product name "WPF1600-B"), the disintegration stress (unit: kg) of the flame retardant granulate after drying was measured. The measured value was the average value of 25 granulates.

[0070]

Table 2

[0071] As shown in Table 2, Reference Example 2, Examples 2 ~5 were able to obtain pellet-shaped flame retardant granulates with a stable pellet shape, high granulation speed, and appropriate hardness. Reference Example 1 is the result (FRG-C1) of mixing a powdery flame retardant, a binder, and water at once and making a mixture with a combination of blades with weak powder stirring ability (upper blade: ST blade, lower blade: A0 blade), but the disintegration strength was not stable. On the other hand, Comparative Example 1 (FRG-C2) has inferior disintegration strength of the flame retardant granulate compared to Example 4.

[0072] Reference Example 3 75 parts by weight of polyamide 6 resin (manufactured by Unitika Ltd., trade name "Unitika Nylon 6 A1030BRL-1") and 25 parts by weight of a flame retardant granulate (FRG-1) were put into a twin-screw extruder (manufactured by Toshiba Machine Co., Ltd., trade name "TEM18SS", L / D = 48), and continuous melt-kneading was carried out to produce pellets of a resin composition of nylon 6 resin and a powdery flame retardant ("A-1" in Table 1). The pellets of polyamide 6 and the flame retardant granulate (FRG-1) were pre-mixed in advance and quantitatively put into the twin-screw extruder from the hopper position at the most upstream part of the extruder through a feeder. The cylinder temperature of the extruder was set to 230 °C from the middle part and later of the extruder. The rotation speed of the main screw of the twin-screw extruder was 100 rpm, and the discharge speed was 5 kg / Hr. The melt-kneaded resin composition was extruded in a strand shape, cooled in a water-cooling bath, and made into pellets with a length of about 3 mm. The obtained resin composition is excellent in the supply stability of the powdery flame retardant ("A-1" in Table 1) to the extruder, also excellent in the melt-kneading dispersibility of the powdery flame retardant A-1, excellent in the take-up stability of the strand, and exhibited excellent flame retardancy.

[0073] [Examples 7, 8] Except for changing to the composition shown in Table 3, Reference Example 3 Pellets of a resin composition of nylon 6 resin and a powdery flame retardant ("A-1" in Table 1) were produced in the same manner. All of the obtained resin compositions were excellent in production stability, also excellent in the melt-kneading dispersibility of the powdery flame retardant (A-1), and also excellent in flame retardancy.

[0074] [Comparative Example 2] Nylon 6 was passed through the extruder alone and pelletized.​​

[0075] [Comparative Example 3] Melting kneading was carried out in the same manner as in Example 7 except that the powdery flame retardant (A-1) was used instead of the flame retardant granule (FRG-2), and an attempt was made to produce pellets. A bridge of the powdery flame retardant (A-1) occurred at the shoot opening, and stable continuous production could not be carried out. From the comparison between Example 7 and Comparative Example 3, it is clear that the flame retardant granule of the present invention can stably and continuously produce a resin composition even when producing a resin composition with a high blending ratio of the powdery flame retardant.

[0076] [Evaluation] Reference Example 3, Example 7 The pellets of the resin compositions obtained in Examples ~8 and Comparative Examples 2 and 3 were subjected to the following evaluations The results are shown in Table 3. (a) Feed characteristics of the flame retardant granule (or powdery flame retardant) The continuous feeding situation at the inlet of the extruder was confirmed, and the granulation property was evaluated according to the following criteria. 〇: Can be stably supplied. ×: In the supply of the powdery flame retardant, bridging or adhesion to the apparatus wall surface may occur, and the feed is unstable. (b) Dispersibility The dispersibility in the melting kneading of the resin and the flame retardant granule was evaluated according to the following criteria from the feel of the surface of the strand of the molten mixture. 〇: The surface is smooth and the dispersibility is good. ×: The surface is rough and the dispersibility is poor. (c) Granulation stability of the resin composition pellets The draw stability of the strand of the molten kneaded product of the flame retardant and the thermoplastic polymer extruded from the die was evaluated according to the following criteria. 〇: The strand can be stably granulated into a resin composition without breakage. ×: Strand breakage occurs because the raw material supply stability is unstable. (d) Flame retardancy evaluation The strands of the melt-kneaded product were cut out to about 10 cm, fixed perpendicular to the strands, and ignited using a gas burner (flame height: 1 cm) at the bottom, and the combustion sustainability was evaluated according to the following criteria. AA: Hardly ignites (excellent flame retardancy) A: Ignites but self-extinguishes (dripping may occur) B: Does not extinguish

[0077]

Table 3

Claims

1. A flame retardant granule formed by binding a non-bromine-based powdery flame retardant, wherein the flame retardant granule contains a binding powdery flame retardant, the binding powdery flame retardant is a non-bromine-based powdery flame retardant having a melting point of 40°C or more and less than 150°C, the diameter of the flame retardant granule is 2 mm to 5 mm, the breaking stress of the flame retardant granule in a wooden hardness tester is 1.0 kg to 5 kg, the flame retardant granule does not contain a binder other than the binding powdery flame retardant, Flame retardant granule.

2. The flame retardant granule according to claim 1, wherein the non-bromine-based powdery flame retardant is at least one selected from the group consisting of a phosphorus-containing compound-based flame retardant, a nitrogen-containing compound-based flame retardant, an inorganic flame retardant, and a metal salt-based flame retardant.

3. The flame retardant granule according to claim 1, wherein the non-bromine-based powdery flame retardant having a melting point of 40°C or more and less than 150°C as the binding powdery flame retardant is at least one selected from the group consisting of an aromatic phosphate ester compound, an aromatic condensed phosphate ester compound, and a cyclic phosphazene compound.

4. The flame retardant granule according to claim 1, wherein the number average particle diameter of the non-bromine-based powdery flame retardant is 5 μm to 300 μm.

5. A mixing step of mixing the non-bromine-based powdery flame retardant and water, a granulation step of granulating the mixture obtained through the mixing step to obtain a granule precursor, and a drying step of drying the granule precursor, A method for manufacturing a flame retardant granule according to any one of claims 1 to 4.

6. The method for manufacturing a flame retardant granule according to claim 5, wherein in the granulation step, granulation is performed by a semi-wet granulation method.

7. The method for manufacturing a flame retardant granule according to claim 5, wherein in the granulation step, granulation is performed by a disk pelletizer method.

8. Use of the flame retardant granule according to any one of claims 1 to 4 as a raw material for a molding material or a thermoplastic resin compound.

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